阅读说明：本技术 具有可变透射率的光学元件和具有这种光学元件的屏幕 (Optical element with variable transmission and screen with such an optical element ) 是由 安德烈亚斯·布雷古拉 安德烈·胡贝尔 扬尼克·布尔金 A·P·纳里 杨进田 马库斯·克里普 于 2020-08-18 设计创作，主要内容包括：本发明涉及一种光学元件,包括基本上板状的基底(S),该基底具有构造为光入射面的第一大面和构造为光出射面的第二大面。光学元件还包括设置在第一大面和第二大面之间的流体或支架基质(F),以及能够以电泳或磁泳方式移动的粒子(P),该粒子与一个或多个波长或波长范围的光相互作用。光学元件还包括面状的电磁开关机构,电磁开关机构形成在基底(S)中的一个大面或两个大面上和/或大面之间,并且电磁开关机构在接通状态下产生电磁场,由此粒子(P)在流体或支架基质(F)中移动,使得光学元件对于波长或波长范围的经由光入射面入射到基底(S)中的光的与角度相关的透射率由于与粒子(P)的相互作用而发生改变。光学元件可以以各种方式实现。(The invention relates to an optical element comprising a substantially plate-shaped substrate (S) having a first large surface configured as a light entry surface and a second large surface configured as a light exit surface. The optical element further comprises a fluid or scaffold matrix (F) arranged between the first and second large faces, and electrophoretically or magnetophoretically movable particles (P) which interact with one or more wavelengths or wavelength ranges of light. The optical element further comprises a planar electromagnetic switching mechanism which is formed on and/or between one or both large faces in the substrate (S) and which, in the switched-on state, generates an electromagnetic field, as a result of which the particles (P) move in the fluid or carrier matrix (F) such that the angle-dependent transmission of the optical element for light of a wavelength or wavelength range which is incident into the substrate (S) via the light entry face changes as a result of interaction with the particles (P). The optical element may be implemented in various ways.)

1. An optical element comprising

A substantially plate-shaped substrate (S) having a first large surface configured as a light incidence surface and a second large surface configured as a light exit surface,

a fluid or scaffold matrix (F) arranged between the first and second large faces and containing particles (P) capable of moving electrophoretically or magnetophoretically, said particles interacting with one or more wavelengths or wavelength ranges of light,

a planar electromagnetic switching mechanism formed on one or both large faces in the substrate (S) and/or between the large faces in the substrate (S), which electromagnetic switching mechanism in the on-state generates an electromagnetic field, whereby the particles (P) are moved in the fluid or carrier matrix (F) such that the angle-dependent transmission of the optical element for light of the wavelength or wavelength range incident into the substrate (S) through the light entrance face changes due to interaction with the particles (P),

wherein, in a first alternative, the particles (P) absorb or scatter light of the wavelength or wavelength range, the fluid or scaffold matrix (F) contains up to 60% by volume of the particles (P) and the electromagnetic field acts between the large faces, or

In a second, third and fourth alternative, the optical element comprises a plurality of cavities embedded in the substrate (S), the cavities forming lamellae either individually or in groups, each group forming one lamella, which extend between the first and second large faces, and each lamella having a longitudinal side and a narrow side, wherein the narrow side of each lamella is arranged in the region of the large faces and the longitudinal side connects the narrow sides, wherein

In a second alternative, the particles (P) absorb or scatter light of the wavelength or wavelength range incident at an angle into the substrate (S) through the light incidence surface, so that the light impinges on cavities formed as fluid cavities (R) which each individually form a thin layer and are filled with a fluid (F), wherein the fluid (F) contains at most 50% by volume of the particles (P) and the electromagnetic switching mechanism generates an electromagnetic field which acts in the cavity in the on state, or

In a third alternative, the fluid or scaffold matrix (F) filling the cavity comprises at most 95% by volume of particles (P) comprising at least first particles (P) of a first type that absorb light having said wavelength or wavelength range_A) And/or second particles (P) of a second type reflecting and/or scattering light having said wavelength or wavelength range_B) Wherein only one particle (P) is present_A、P_B) In the case of (A), said fluid or scaffold matrix (F) realizes another particle (P)_B、P_A) Such that the optical element changes its angle-dependent transmission for light of said wavelength incident at an angle into the substrate (S) via a light entrance face, such that the light impinges on the layer, or

In a fourth alternative, the fluid or scaffold matrix (F) filling the cavity contains at most 95% by volume of the particles (P) designed as Janus particles and respectively having at least one first structure (P)₁) And a second structure (P) different from the first structure₂) Wherein the first structure (P)₁) Absorbs light of said wavelength or wavelength range, and said second structure (P)₂) Reflecting and/or scattering the wavelength or wavelength range of light such that the optical element is incident at an angle into the substrate (S) via a light entrance faceThe angle-dependent transmission of light having said wavelength or wavelength range is changed so that the light impinges on the thin layer.

2. An optical element having a scaffold matrix designed as a polymer matrix, preferably as a gel matrix.

3. Optical element according to claim 1 or 2 and according to said first, second or third alternative, wherein said particles (P) according to the first or second alternative and first particles (P) of the first type according to the third alternative_A) Designed as nanoparticles, quantum dots and/or colorants and having a spatial extension of at most 200nm or at most 100nm or at most 50nm or at most 20 nm.

4. Optical element according to claim 3 and according to a third alternative, wherein the second particles (P) of the second type_B) Designed as transparent spheres or reflective spheres with a diameter between 5nm and 5000 nm.

5. Optical element according to claim 3 or 4, characterized in that the particles (P) or particles of a first type (P)_A) Designed as BPQD (Black Quantum dot phosphate), lead sulfide (P)_BS), CdSeSe quantum dots, azo colorants and/or designed as metal oxide particles, preferably made of chromium (IV) oxide or Fe₂O₃And each has a size between 2nm and 50nm, inclusive.

6. Optical element according to claim 3, characterized in that the particles (P) are designed as paramagnetic bodies composed of a paramagnetic or diamagnetic carrier material with a relative permeability between 0.5 and 2, preferably melamine resin or polystyrene, preferably as spheres with a diameter of at least 100nm, coated with paramagnetic or superparamagnetic nanoparticles with a relative permeability of more than 10, preferably coatedCoated with Fe₂O₃Nanoparticles, or the support material is impregnated with the nanoparticles.

7. An optical element according to claim 1 or 2 and according to a third alternative, characterized in that said first particles (P) of the first type_A) And second particles (P) of said second type_B) Embedded in a fixed position capsule body which is positioned at the edge face of the cavity or forms the cavity.

8. An optical element according to claim 1 or 2 and according to a fourth alternative, characterized in that the particles are positionally fixedly positioned at an edge face of the cavity.

9. Optical element according to claim 1 and according to a fourth alternative, characterized in that the particles (P) are designed with a spherical surface in which the first and second regions respectively consist of a hemisphere of the spherical surface.

10. Optical element according to claim 9, characterized in that the particles (P) are designed as micro-particles and have a spatial extension of maximally 200 μ ι η, preferably maximally 50 μ ι η, particularly preferably maximally 20 μ ι η.

11. Optical element according to claim 9 or 10, characterized in that the particles (P) are formed of a transparent material, preferably latex, PMMA, polystyrene, melamine resin or silicon dioxide, and one of the hemispheres is coated with a layer of metal or metal nanoparticles to achieve the electrophoretic properties.

12. Optical element according to claim 9 or 10, characterized in that the particles (P) are formed of a transparent material, preferably polystyrene, melamine resin or silicon dioxide, one of the hemispheres being ferromagnetic and absorbing in order to achieve magnetophoretic propertiesCovered by a metal layer or metal oxide layer or ferromagnetic nanoparticle layer, preferably by means of Fe₂O₃The nanoparticle layer is covered and the other hemisphere is covered by means of a reflective layer, preferably a silver or aluminum layer or a white layer.

13. Optical element according to claim 11 or 12, characterized in that the particles (P) have a diameter greater than 200nm and the thickness of the applied layer is greater than 10 nm.

14. Optical element according to claim 1, characterized in that the particles (P) are electrically charged and the electromagnetic switching mechanism is designed as electrodes for generating an electrostatic or dynamic electric field, or the particles (P) are magnetic and the electromagnetic switching mechanism is designed as an electrically conductive layer for generating a static or dynamic magnetic field, so that the electrophoretically or magnetophoretically particles (P) in the electric or magnetic field move in the fluid or scaffold matrix (F).

15. Optical element according to claim 14 and according to the third alternative, characterized in that said first particles (P)_A) And said second particles (P)_B) A translational motion along an electric or magnetic field.

16. An optical element according to claim 14 and according to a fourth alternative, characterised in that the movement is a rotational movement around a predetermined axis parallel to the longitudinal or narrow side of the lamella.

17. Optical element according to claim 1, characterized in that by means of the electromagnetic switching mechanism and control circuit at least two operating states are defined depending on the position of the particles (P), wherein the angle-dependent transmission, measured in a direction perpendicular to the longitudinal extension of the lamellae, is greater than 50% in a first operating state B1 and less than 50% in a second operating state B2, in the angular range of greater than 30 ° to 90 ° relative to the surface normal of the second large face of the substrate and in the presence of lamellae.

18. An optical element according to claim 17 and according to a first alternative, characterized in that the first part of the electromagnetic switching mechanism is designed as a planar electrode E1 on the first and/or second large face and the second part of the electromagnetic switching mechanism is designed as an electrode E2 in the shape of a thin layer between the first and second large face, wherein the thin layer forms an angle between 0 ° and 30 °, inclusive, with the surface normal of the first or second large face and in that in the first operating state B1 more than 70% of the particles (P) are located at or near the electrode E1, respectively, and in the second operating state B2 more than 70% of the particles (P) are located at or near the electrode E2, respectively, such that in an angular range around the surface normal of the second large face of the substrate more than 30 °, the angle-related transmittance is greater than 60% in the first operating state B1 and in the second operating state B2 The lower is less than 10%.

19. The optical element according to claim 17 and according to a first alternative, characterized in that all electromagnetic switching mechanisms are designed as planar electrodes EPN on a first large face and a second large face, which planar electrodes have a polarity that is reversible between positive and negative, and in a first operating state B1 the electrodes EPN on the first large face have a positive polarity and the electrodes EPN on the second large face have a negative polarity, or the electrodes EPN on the first large face have a negative polarity and the electrodes EPN on the second large face have a positive polarity, such that more than 70% of the particles (P) are respectively not further away from the electrodes EPN than the largest quarter of the thickness of the fluid or the scaffold matrix and/or are positioned in the fluid or the scaffold matrix (F) in a distributed manner and in a second operating state B2 normal, viewed along the face of the first large face or the second large face, the negatively polarized electrodes EPN on the first large face are positioned opposite the negatively polarized electrodes EPN on the second large face, and the positively polarized electrodes EPN on the first large face are placed opposite the positively polarized electrodes EPN on the second large face, wherein one negatively polarized electrode EPN is arranged between two positively polarized electrodes EPN on each large face along the preferential direction and one positively polarized electrode EPN is arranged between two negatively polarized electrodes EPN such that more than 70% of the particles are respectively located between electrodes EPN of the same polarity, whereby the angle-dependent transmission is greater than 60% in the first operating state B1 and less than 5% in the second operating state B2 in an angular range of greater than 30 ° with respect to the surface normal of the second large face of the substrate.

20. An optical element according to claim 17 and according to a first alternative, characterized in that,

in addition to the particles (P), further particles (P) are contained in the fluid or scaffold matrix (F)_C) Wherein the other particles (P)_C) Reflect and/or scatter and/or transmit one or more wavelengths or wavelength ranges of light,

all the electromagnetic switching mechanisms are arranged as planar electrodes EPN on the first large face and the second large face, the planar electrodes EPN having a polarity reversible between positive and negative, wherein the negatively polarized electrode EPN on the first large face is placed opposite the negatively polarized electrode EPN on the second large face and the positively polarized electrode EPN on the first large face is placed opposite the positively polarized electrode EPN on the second large face as viewed along the surface normal of the first large face or the second large face, and one negatively polarized electrode EPN is arranged between the two positively polarized electrodes EPN on each large face along the preferential direction, and one positively polarized electrode EPN is arranged between the two negatively polarized electrodes EPN, as long as no holes having no electrode are arranged between the two positively polarized electrodes EPN or the two negatively polarized electrodes EPN, wherein the holes are periodically arranged,

the particles (P) accordingly have a charge polarity, and the further particles (P)_C) Accordingly having the other polarity of charge,

in the two operating states B1 and B2, more than 70% of the particles (P) are respectively located between the positive polarization electrodes EPN and, complementary thereto, more than 70% of the other particles (P)_C) Respectively between the negative polarized electrodes EPN, or more than 70% of the particles (P) are respectively between the negative polarized electrodes EPN, andat 70% of other particles (P)_C) Are respectively located between the positive polarisation electrodes EPN and here, in a first operating state B1, the further particles (P)_C) Respectively, between homopolar electrodes respectively adjacent to the holes, and in a second operating state B2, the particles (P) are respectively between homopolar electrodes respectively adjacent to the holes,

such that, over an angular range of more than 30 ° with respect to the face normal of the second major face of the substrate, the angle-dependent transmission is more than 60% in the first operating state B1 and less than 5% in the second operating state B2.

21. Optical element according to claim 20, characterised in that the further particles (P) to be electrophoretically moved that scatter light_C) Formed of polystyrene, melamine resin or silica having a particle size of between 20nm and 10 μm, and/or other particles (P) reflecting light_C) Formed as silver nanoparticles having a particle size between 10nm and 50 nm.

22. Optical element according to claim 20 or 21, characterized in that further particles (P) to be magnetophoretically moved scattering light_C) Designed paramagnetic, preferably infiltrated and/or coated with nanoparticles made of magnetizable material, preferably nickel.

23. Optical element according to any one of claims 20 to 22, characterized in that further particles (P) are present as well_C) Alternatively, a lamellar cavity arranged in lamellae is designed into the light guide, said lamellar cavity containing a gel matrix (F) that scatters light_S) The particles (P) move in the gel matrix according to the operating state.

24. An optical element according to claim 17 and according to the second alternative, characterised in that in the first operating state B1 more than 70% of the particles (P) are located in a region on a side of a fluid chamber (R) at which the electromagnetic switching mechanism is formed, respectively, and in that in the second operating state B2 the switching mechanism is configured such that no static or alternating electromagnetic field is present, more than 50% of the particles (P) being distributed mostly uniformly in the fluid chamber (R) such that the angle-dependent transmission is greater than 60% in the first operating state B1 and less than 5% in the second operating state B2, measured in an angular range of greater than 30 ° relative to the surface normal of the second large face of the substrate and in a direction perpendicular to the longitudinal extension direction of the lamellae.

25. Optical element according to claim 17 and according to a third or fourth alternative, characterized in that in a second operating state B2 the first particles (P) are_A) Or a first structure (P) of said particles (P)₁) Respectively, on the longitudinal sides of the lamina, wherein, in the first configuration (P)₁) In the case of (A), the first structure faces the longitudinal side and the second structure (P)₂) Away from the longitudinal side and in a first operating state B1, second particles (P)_B) Or a second structure (P) of said particles (P)₂) Respectively, on the longitudinal sides of the lamina, in the second configuration (P)₂) In the case of (A), the second structure faces the longitudinal side and the first structure (P)₁) Away from the longitudinal side such that the angle-dependent transmission, measured in a direction perpendicular to the longitudinal extension direction of the lamellae and over an angular range of more than 30 ° with respect to the face normal of the second large face of the substrate, is more than 60% in a first operating state B1 and less than 5% in a second operating state B2.

26. Optical element according to claim 17 and according to a third or fourth alternative, characterized in that in a first operating state B1 the first particles (P) are_A) Or a first structure (P) of said particles (P)₁) Respectively at the narrow sides of the thin layer, wherein, in the first structure (P)₁) In the case of (A), the first structure faces the narrow side and the second structure (P)₂) Away from the narrow side and in a second operating state B2Two particles (P)_B) Or a second structure (P) of said particles (P)₂) Respectively at the narrow sides of the thin layer, in a second configuration (P)₁) In the case of (A), the second structure faces the narrow side and the first structure (P)₂) Away from the narrow side such that the angle-dependent transmission, measured in the angular range of more than 30 ° with respect to the surface normal of the second large side of the substrate and in a direction perpendicular to the longitudinal extension direction of the lamellae, is more than 60% in a first operating state B1 and less than 5% in a second operating state B2.

27. An optical component as claimed in claim 17, characterized in that the electromagnetic switching mechanism is divided into a plurality of individually switchable sections, so that partial switching can be effected between the first operating state B1 and the second operating state B2.

28. Optical element according to claim 1, characterized in that the electromagnetic switching mechanism is at least 50% transparent in the wavelength range visible to the human eye for light perpendicularly incident into the substrate (S) via the light entrance face.

29. Optical element according to claim 1, characterized in that there are several types of particles in the fluid or in the scaffold matrix (F), which differ in absorption properties and/or transport properties in an electromagnetic field.

30. An optical element according to the second, third or fourth alternative, characterized in that the lamellae are mutually oriented parallel or grid-like with crossing regions.

31. An optical element according to the second, third or fourth alternative, according to claim 1, characterized in that said thin layer is inclined with respect to the perpendicular bisector of said substrate S within an angular range of-30 ° to +30 ° or-10 ° to +10 °.

32. An optical element comprising

A substantially plate-shaped substrate (S) having a first large surface configured as a light incidence surface and a second large surface configured as a light exit surface,

a plurality of cavities embedded in the substrate (S), which cavities form lamellae individually or in groups depending on the size of the cavities, wherein each group forms one lamella and each lamella has a longitudinal side and a narrow side extending between a first and a second large face, the narrow side of each lamella is arranged in the region of the large faces and the longitudinal sides connect the narrow sides, and the spaces between the lamellae contain at least one opaque material (M),

a fluid or scaffold matrix (F) filling said cavity (R), said fluid or scaffold matrix (F) containing up to 50% by volume of other particles (P) capable of moving in an electrophoretic or magnetophoretic manner_C) Said other particles reflecting and/or scattering light of one or more wavelengths or wavelength ranges in the range visible to the human eye,

and an electromagnetic switching mechanism which is formed in a planar shape on a narrow side of the thin layer in the substrate (S), and which generates an electromagnetic field acting in the thin layer in the ON state, thereby causing other particles (P)_C) Moving in a fluid or a scaffolding matrix (F) such that the optical element is aligned with other particles (P)_C) The angle-dependent transmission of the reflected and/or scattered light of the wavelength or wavelength range is changed, the light being incident into the substrate (S) through the light incidence surface at an angle such that the light impinges on the thin layer.

33. Optical component according to claim 32, in which the further particles (P) are in a first state B1_C) Is arranged in the vicinity of the upper narrow side of the lamellae, whereby light confined in the propagation direction due to the opaque material (M) between the lamellae is assisted on the upper narrow side by means of further particles (P)_C) Scattered and/or reflected in multiple directions, the light intruding through the light incident sideInto the substrate and inside the thin layer, and in a second state B2, the other particles (P)_C) Is arranged in the vicinity of the narrow side of the lower part of the thin layer, whereby light penetrating into the substrate (S) through the light entrance side is due to the further particles (P)_C) Is scattered and/or reflected, however limited in the propagation direction by the opaque material (M) between the thin layers.

34. An optical element comprising

A plate-shaped substrate (S) having a first large surface configured as a light incidence surface and a second large surface configured as a light emission surface,

a fluid or scaffold matrix (F) arranged between the first and second large faces and containing up to 60% by volume of particles (P) capable of moving electrophoretically or magnetophoretically, wherein there are a plurality of particles (P) which absorb or scatter light of one or more wavelengths or wavelength ranges,

a planar electromagnetic switching mechanism formed on one or both large faces in the substrate (S) and/or formed between large faces in the substrate (S), which in the on-state generates an electromagnetic field acting between the large faces, thereby causing particles (P) to move in the fluid or carrier matrix (F),

such that the transmittance of the optical element for light of the wavelength or wavelength range absorbed by the particles (P) is changed, wherein the transmittance is greater than 50% in a first operating state B1 and less than 50% in a second operating state B2 with respect to the direction of the surface normal of the second large face of the substrate (S).

35. An optical element comprising

A plate-shaped substrate (S) having a first large surface configured as a light incidence surface and a second large surface configured as a light emission surface,

a plurality of cavities (R) embedded in the substrate (S), the cavities each having one or more surfaces,

a fluid (F) filling the cavity (R), the fluid (F) containing up to 20% by volume of particles (P) capable of electrophoretically or magnetophoretically moving, the particles absorbing or scattering light of one or more wavelengths or wavelength ranges,

-a planar electromagnetic switching mechanism formed on one or more surfaces of the cavity (R) in the substrate (S), which in an on-state generates an electromagnetic field acting within the cavity (R), whereby the particles (P) move in the fluid such that the transmittance of the optical element for light of the wavelength or wavelength range absorbed by the particles (P) changes, wherein the transmittance is larger than 50% in a first operating state B1 and smaller than 50% in a second operating state B2 with respect to the direction of the surface normal of the second large face of the substrate (S).

36. A screen operable in a first operating state B1 for a free-viewing mode and in a second operating state B2 for a limited-viewing mode, the screen comprising at least one optical element according to any one of claims 1 to 33 and an image-reproducing unit disposed behind or in front of the at least one optical element for viewing from a viewer.

Technical Field

In recent years, great progress has been made in enlarging the viewing angle of LCDs. However, there are often situations where a very large viewing area of the screen may be disadvantageous. There is an increasing amount of information available on mobile devices such as laptops and tablet PCs, such as bank data or other personal information, as well as sensitive data. Therefore, people need to control who can see the sensitive data; people must be able to choose between a wide viewing angle to share information with other displays on their displays, for example when watching vacation pictures, or also for advertising purposes. On the other hand, if people want to process image information secretly, they need a smaller viewing angle.

Similar problems arise in vehicle manufacture: there, the driver should not be distracted by image content, for example digital entertainment programs, if the engine has started, but the passenger also wants to consume the image content during the ride. Therefore, a screen capable of switching between the respective display modes is required.

Background

Additional films based on microlayers have been used in mobile displays to achieve their visual data protection. However, these films cannot be switched (back and forth), they must always be placed by hand and then removed again. It must also be delivered separately to the display if it is just not needed. Furthermore, the main drawback of using such thin films is associated with the consequent loss of light.

US 6,765,550B 2 describes such protection from view through a microlayer. The major disadvantage here is the mechanical removal or mechanical installation of the filter and the loss of light in the protected mode.

US 5,993,940 a describes the use of a film having uniformly arranged smaller prism strips on its surface to achieve a privacy mode. Development and manufacturing is quite costly.

In WO 2012/033583 a1, switching between free and limited viewing is produced between so-called "chromium ionosphere" by means of controlling the liquid crystal. Light losses occur and are relatively expensive.

US 2012/0235891 a1 describes a very expensive backlight in a screen. According to fig. 1 and 15, not only a plurality of light guides are used here, but also other complex optical elements, such as lenticular elements 40 and prism structures 50, which convert the light from the rear illumination means on the way to the front illumination means. This is expensive and complex to implement and is also associated with light loss. According to the variant according to fig. 17 in US 2012/0235891, the two light sources 4R and 18 produce light with a narrow illumination angle, wherein the light from the rear light source 18 is only complexly converted into light with a larger illumination angle. As described above, such complicated conversion seriously reduces the luminance.

According to JP 2007-155783A, special, computationally complex and to-be-manufactured optical surfaces 19 are used, which then deflect the light into various narrower or wider regions depending on the angle of incidence of the light. These structures are similar to fresnel lenses. Furthermore, there are interference edges which deflect the light in undesired directions. Therefore, it is not clear whether a truly meaningful light distribution can be achieved.

US 2013/0308185 a1 describes a special light guide designed with steps that emit light in different directions over a large face depending on the direction in which the light guide is illuminated from the narrow side. Thus, under interaction with a transmissive image reproduction device, such as an LC display, a screen can be produced that can be switched between a free mode and a limited mode. It is disadvantageous here that the limited visual effect can be generated either only for the left/right or for the up/down, but not simultaneously for the left/right/up/down, which is necessary, for example, for a specific counting process. Furthermore, even in the limited viewing mode, the afterglow is still visible from the blocked viewing angle.

WO 2015/121398 a1 of the applicant describes a screen with two modes of operation, in which, for switching the modes of operation, the necessary scattering particles are present in the volume of the respective light guide. The scattering particles of polymer selected there, however, generally have the disadvantage that light is coupled out from both large surfaces, so that approximately half of the available light is radiated in the wrong direction, i.e. toward the backlight, and cannot be recovered there to a sufficient extent due to the construction. Furthermore, the scattering particles of polymer distributed in the volume of the light guide can lead, in particular at higher concentrations, to scattering effects which reduce the viewing protection effect in the protected operating mode.

The above-described methods and devices generally have the disadvantage of significantly reducing the brightness of the main screen and/or requiring complex and expensive optical elements for mode switching and/or reducing the resolution in the freely viewable mode.

Disclosure of Invention

It is therefore an object of the present invention to describe an optical element which can influence the transmission in dependence on an angle (optionally perpendicularly) and which can be switched between at least two operating states. The optical element should be capable of being implemented at low cost and be particularly applicable to various types of screens to allow switching between a view-protected mode and a free-viewing mode, wherein the resolution of such screens is not substantially reduced. Alternatively, the optical element may be able to suffice without the lamellar cavity.

According to the invention, this object is achieved by an optical element which can be present in different embodiments. In any case, the optical element comprises a substantially plate-shaped substrate having a first large face as light entry face and a second large face as light exit face, and a fluid or support matrix arranged between the first and second large faces and containing electrophoretically or magnetophoretically movable particles which interact with light of one or more wavelengths or wavelength ranges, preferably in the range visible to the human eye. The interaction with light is achieved by absorption, reflection and/or scattering, if appropriate also by transmission. The light-absorbing particles are also referred to as absorbing particles. Particles that reflect, scatter or transport light under interaction are also referred to as deflecting particles.

The optical element further comprises a planar electromagnetic switching mechanism formed on one or both large faces in the substrate and/or between the large faces, which electromagnetic switching mechanism in the on-state generates an electromagnetic field, whereby the particles move in the fluid or carrier matrix such that the angle-dependent transmission of the optical element for light of said wavelength or wavelength range incident into the substrate via the light entrance face changes due to interaction with the particles. The term "electromagnetic switching mechanism" is to be understood here as a purely electrical switching mechanism for generating an electric field, an electromagnetic switching mechanism for generating a magnetic field and a combination of both.

In a first alternative, the particles absorb or scatter light of said wavelength or wavelength range, and the fluid or scaffold matrix contains up to 60% by volume of the particles, wherein the electromagnetic field acts between the large faces.

In a second, third and fourth alternative, the optical element comprises a plurality of cavities embedded in the substrate, which cavities form lamellae individually or in groups depending on their size, wherein each group forms one lamella, the lamellae extend between a first large face and a second large face, and each lamella has a longitudinal side and a narrow side, the narrow side of each lamella being arranged in the region of the large faces, and the longitudinal sides connecting the narrow sides.

In a second alternative, the particles absorb or scatter light of the above-mentioned wavelength or wavelength range, which is incident at an angle through the light entrance face into the substrate and impinges on the cavity. The chambers are each individually formed as a thin layer and filled with a fluid, wherein the fluid contains at most 50% by volume of particles, preferably at most 20% by volume for a greater freedom of movement, and the electromagnetic switching mechanism generates an electromagnetic field which acts in the chambers in the switched-on state.

In a third alternative, the fluid or scaffold matrix filling the cavities contains up to 95% by volume of particles. Here, the particles may comprise at least first particles P of a first type absorbing light of said wavelength or wavelength range_AAnd/or second particles P of a second type reflecting and/or scattering light of said wavelength or wavelength range_B. In the presence of only one type of particles (first particles P of a first type)_AOr second particles P of a second type_B) In the case of (2), the fluid or scaffolding matrix acts as the other type of particle. In general, due to the electric field, the angle-dependent transmission of the optical element for light of the wavelength which is incident at an angle into the substrate via the light entrance face changes such that the light impinges on the thin layer.

Finally, in a fourth alternative, the fluid or scaffold matrix used to fill the cavity also contains up to 95% by volume of particles, which are configured as so-called Janus particles. The term "Janus particle" is understood here to mean a micro-or nanoparticle whose surface is separatedHas at least two physical properties different from each other. For example, a spherical particle may be divided into two hemispheres, wherein each hemisphere has different properties, which may be achieved, for example, by a corresponding coating/functionalization, or also by inherent structural differences. Thus, each Janus particle has at least one particle with a first structure P₁And a second structure P different from the first structure₂Wherein the first structure P₁Absorbs light of said wavelength or wavelength range, and a second structure P₂Reflecting and/or scattering light of said wavelength or wavelength range. In this way, the angle-dependent transmission of the optical element for light of the wavelength which is incident at an angle into the substrate via the light entry face is also changed such that the light impinges on the thin layer.

The scaffold matrix which advantageously fills the cavity is, for example, designed as a polymer matrix, preferably as a gel matrix. The fluid may be polar or non-polar. Furthermore, the fluid may consist of, for example, water, oil, toluene or formaldehyde, or may be mixed with 10% by volume of ferrofluid and/or electrolyte.

Particles P capable of being moved electrophoretically or magnetophoretically_AOne or more wavelengths or wavelength ranges of the absorbed light preferably lie in the visible spectrum and particularly preferably completely cover this visible spectrum. However, for example when it is desired to influence UV light or IR light, the wavelength or wavelength range may also be outside the visible spectrum for special purposes, for example for the purpose of measurement techniques.

The first and second large faces of the plate-shaped substrate are preferably arranged parallel to each other. However, in a particular design, for example when a particular angle-dependent transmission of the optical element is achieved, the first and second large faces may also be arranged non-parallel to each other, for example wedge-shaped to each other within a defined angle of at most 20 degrees.

The first large side of the plate-shaped substrate, which is configured as a light entry surface, is usually situated on the rear side of the substrate, viewed from the observer's perspective, and, depending on the application scenario of the optical element, is adjacent to, for example, an image reproduction device, a light source or an air volume. The light then exits the last-mentioned object through the light entrance face and is incident into the substrate.

Particles according to the first or second alternative and first particles of the first type P according to the third alternative_ACan be nanoparticles, quantum dots and/or colorants, the particles having a spatial extension of at most 200nm, preferably at most 100nm, preferably at most 50nm, particularly preferably at most 20 nm. However, other designs are possible. "spatial extension" refers to the maximum extension length or hydrodynamic radius in three-dimensional space, depending on the larger of the two. Thus, in the case of spherical particles, the diameter. In the case of chain-like particles, it is the maximum possible distance that two points on the surface of the particle can have from each other accordingly.

These particles according to the first or second alternative and the first particles P of the first type according to the third alternative_ACan be constructed as BPQD (black phosphate), lead sulfide (P)_BS), CdSeSe quantum dots, azo colorants and/or metal oxide particles, preferably made of chromium (IV) oxide or Fe₂O₃And has a size of 2nm to 50nm, inclusive.

Alternatively, the particles according to the first or second alternative and the first particles of the first type P according to the third alternative_ACan be formed as a paramagnetic body, preferably a sphere having a diameter of at least 100nm, from a paramagnetic or diamagnetic carrier material having a relative permeability of between 0.5(0.75 is better) and 2, particularly preferably having a relative permeability of 1, preferably from melamine resin or polystyrene, wherein said body is coated with paramagnetic or superparamagnetic nanoparticles, preferably Fe, having a relative permeability of more than 10₂O₃Nanoparticles, or the infiltration of the support material by these nanoparticles. Other implementation variants are likewise possible.

In the case of the third alternative, the first particles P_AAnd/or second particles P_BAdvantageously embedded in fixed-position capsule bodies which are positioned on the edge face of the cavity orForming a cavity. As described above, the first particles P_AAdvantageously configured as nanoparticles. Second particles P_BAdvantageously formed as transparent or reflective spheres having a diameter between 5nm and 5000 nm.

In the case of the fourth alternative, the particles P are designed as Janus particles which are fixedly positioned on the edge face of the cavity R, but which can rotate freely.

In this fourth variant, the particle P is designed as a Janus particle with a spherical surface, wherein the first region and the second region each consist of a hemisphere of the spherical surface. The particles P are preferably in the form of microparticles and have a spatial extent of at most 200 μm, preferably at most 50 μm, particularly preferably at most 20 μm. It is particularly conceivable to form the Janus particles from a transparent material, preferably polystyrene, melamine resin or silicon dioxide, and to cover one of the hemispheres with a metal layer or a metal nanoparticle layer to achieve electrophoretic properties.

Furthermore, the Janus particles may also be formed of a transparent material, preferably latex, PMMA, polystyrene, melamine resin or silica, and in order to achieve magnetophoretic properties, one of the hemispheres is covered by a ferromagnetic and absorptive metal oxide layer or a ferromagnetic nanoparticle layer, preferably Fe₂O₃Nanoparticle layer, Fe₃O₄The nanoparticle layer or FeO nanoparticle layer, and the other hemisphere is covered with a reflective layer, preferably a silver or aluminum layer, or a white layer.

As described above, the spherical Janus particle is basically characterized in that it has two hemispheres realizing physical properties different from each other. The first hemisphere is intended to scatter or reflect light incident thereon and absorb another incident light. Thus, the light-absorbing anti-first hemisphere satisfies the first particles P of the first type_AOf a second hemisphere of scattered/reflected light satisfies a second particle P of a second type_BThe characteristic of (c).

For example, a Janus particle suitable for use in an optical element according to the present invention may be designed in the following way: a) as described above: transparent spheres (polystyrene, melamine resin or silica) or scattering spheres with absorbing hemispheres; b) a colored or black sphere with reflective hemispheres; and c) spheres having one reflective hemisphere each and one absorptive hemisphere each.

The scattering spheres can be made, for example, by means of TiO in polystyrene spheres₂Nanoparticles or silica nanoparticles. In general, all suitable materials having a white scattering or reflecting property can be considered. The refractive index contrast of the nanoparticles used with respect to the spherical material of the Janus particles causes the transparent spheres to scatter.

Alternatively, as an implementation of Janus particles, colored or black spheres, for example made of polystyrene, and filled with absorbing nanoparticles, quantum dots or colorants, may also be used. Such examples and particles P_AThe same applies to the examples of (1). Chromium (IV) oxide spheres with ferromagnetic properties may also be used.

The reflective hemisphere can be converted, for example, by means of a film or nanoparticles of aluminum, chromium, silver or another metal, for example for the second particles P of the second type_BAs described. For absorptive hemispheres, e.g. carbon, chromium (IV) oxide, Fe₂O₃、Fe₃O₄Or FeO can be as a film or as for P_BThe planar nanoparticles.

The electrophoretic properties are determined by the properties of the surface. This can be improved or controlled by surface functionalization. In order for the Janus particles to be magnetophoretic, either the sphere itself, i.e. the material of the sphere, must be magnetophoretic or one of the hemispheres, i.e. the surface coating in that hemisphere, must be magnetophoretic. The magnetic material is, for example, nickel, iron or chromium (IV) oxide. In the selection of the material, care must be taken that the magnetic dipole of the sphere is permanent so that the Janus particles can be rotated in a targeted manner. This can be achieved, for example, by ferromagnetic Janus particles.

Typically, the Janus particles are larger than 200nm in diameter and the thickness of the applied layer is larger than 10nm, but may also be above or below these values.

It is also advantageous that all particles P present also have a surface functionalization, in particular a higher zeta potential, on the one hand for stabilization in a fluid or scaffold matrix and on the other hand for improving the electrophoresis, i.e. the promotion of the electrophoresis, as far as particles capable of electrophoretic movement are concerned. This can be converted, for example, by PVP (polyvinylpyrrolidone) or PEG (polyethylene glycol) for aqueous systems.

In the case of the second, third and fourth alternative, the optical element comprises a plurality of cavities embedded in the substrate, which cavities form individual lamellae, or are combined in groups, depending on the size of the cavity, wherein each group forms one lamella. These cavities, which are combined individually or in groups and are configured in lamellar fashion, with longitudinal sides and narrow sides extending between a first and a second large face, can for example be oriented parallel to the large faces and have the shape of a cuboid. However, it may also be trapezoidal or curved (e.g. curved) narrow sides. The lamellar structure is to be understood here as meaning that the dimension along the longitudinal sides is significantly longer than the dimension along the narrow sides, for example as is the case with the lamellae of the tines of a comb or of a louver. A plurality of lamellae is also usually arranged parallel to one another along their longitudinal direction; a grid-like arrangement is also conceivable.

In the case of a cuboid shape (excluding the cuboid shape as a special case), the narrow side is the long side with the smaller area, i.e. the longitudinal side, which in turn usually has the largest area of all six surfaces of the cavity. In general, the narrow sides are arranged parallel or (in addition to the oblique angles described further below) parallel to the large faces of the substrate, while the longitudinal sides are arranged perpendicular or (in addition to the oblique angles) perpendicular to the large faces of the substrate. In contrast, the remaining outer side surfaces are two surfaces, which are not embodied as narrow side and longitudinal side. Furthermore, it is explicitly possible that the cavities at least partially protrude on one or both large faces of the substrate.

Advantageously, the cavities are filled with a scaffold matrix configured as a polymer matrix, for example as a gel matrix. This polymer matrix has a characteristic mesh size. By this mesh size, the smaller particles P have less "drag" than the larger particles P, and thus the smaller particles P and the larger particles P differ in sizeIs moved at the speed of (1). On the one hand, if these particles are designed as first particles P of a first type_AAnd second particles P of a second type_BThis is advantageous for controlling the response time and accelerating the uniform distribution of the particles P; however, this is not relevant for the capsule body and the Janus particles. On the other hand, such a polymer matrix has the advantage that it strongly impedes diffusion and the particles P therefore do not move spontaneously, which is advantageous for the capsule body.

If the cavity is filled with a fluid, a refractive index contrast with respect to the fluid is necessary in the case of scattering particles P. The fluid in the cavity may be polar or non-polar. Furthermore, the fluid may consist essentially of, for example, water, oil, toluene or formaldehyde, or may be mixed with an electrolyte.

In the case of the second to fourth alternatives, the electromagnetic switching means, which are designed in planar fashion on one or more sides of the fluid chamber in the base, are provided, for example, on the narrow sides of the respective chamber.

Preferably in all alternatives the particles P are charged and the electromagnetic switching mechanism is configured as an electrode for generating a static or dynamic electric field, or the particles are magnetic, in particular paramagnetic or superparamagnetic, in which case the electromagnetic switching mechanism is configured as an electrically conductive layer for generating a static or dynamic magnetic field. Application of an electric or magnetic field causes electrophoretic or magnetophoretic particles in the electric or magnetic field to move within the fluid or scaffold matrix.

For example, in the case of applying a uniform electric field, in the case of the second to fourth alternatives, or between two electrodes which are opposed to each other on a large face, the respective electric field lines are formed in parallel at the center of the cavity and show a larger deviation of parallelism at the edges. However, other designs are also possible.

The physical effect that is primarily responsible for the movement of particles when applying electromagnetic, in particular electrostatic, fields is (bi-) electrophoresis or magnetophoresis. In the case of no applied electric field or applied magnetic field, the particles move in the chamber, in particular due to diffusion, and are therefore distributed uniformly in time. Furthermore, for particles no larger than 50nm, gravity does not work; that is, in the case of the second to fourth alternatives the vertical position of the particles in the cavity does not change, or in the case of the first alternative the vertical position of the optical element in the cavity does not change, that is, the particles are held suspended in a fluid or gel matrix.

In the case of the first, third or fourth alternative, the electrodes may be arranged parallel, perpendicular or at another defined angle to the first large face of the substrate S. In the case of the third alternative, the particles P comprise first particles P_AAnd/or second particles P_BFirst particles P_AAnd second particles P_BThe translational motion can be carried out along an electric or magnetic field. In the case of the fourth alternative, if the particle P is designed as a Janus particle, the movement is preferably a rotational movement around a predetermined axis parallel to the longitudinal or narrow side of the thin layer.

At least two operating states are defined by means of the electromagnetic switching mechanism and the control circuit, wherein in a first operating state B1 the angle-dependent transmission is greater than 50% over an angle range of greater than 30 DEG to 90 DEG on the basis of the surface normal of the second large surface of the substrate, and in a second operating state B2 is less than 50%.

In the case of the first alternative, the angular range is measured, for example, in a plane containing the perpendicular bisector as the face normal (i.e., perpendicular to the second major face of the substrate S) and is arranged horizontally from the viewpoint of the observer, i.e., generally positioned such that the observer 'S eyes lie in this plane or a straight line connecting the observer' S eyes is parallel to this plane. This definition also applies to further observations. In the case of the second to fourth alternatives, the angular range is instead measured in a direction perpendicular to the longitudinal extension direction of the lamellar cavity or the lamellae. The direction is also typically arranged such that the eyes of the observer lie in a plane containing the direction or a line connecting the eyes of the observer is parallel to the plane. The longitudinal extent is defined here by a straight line connecting the surface center points of the two outer sides of each cavity or lamella.

In this sense, the angular ranges then include angles within the plane of +/-30 ° to +/-90 °, respectively (i.e. from-90 ° to-30 ° and simultaneously +30 ° to +90 °, respectively, but not between-30 ° to +30 °). The angular range may also vary and, instead of +/-30, also includes ranges of +/-10 to +/-90, +/-20 to +/-90, +/-45 to +/-90 or +/-25 to +/-90. At 90 deg., the angle is on the surface of the substrate.

It is also within the scope of the invention that more than two operating states B1, B2, B3, etc. can be adjusted. For this purpose, for example, in contrast to the variants described above for the operating states B1 and B2, a further electromagnetic field is applied in the third (fourth, fifth, …) operating state, which results in the degree of output of the particles or particle types differing significantly between the operating states, so that in total three or more different angle-dependent transmittances are achieved. This may be advantageous, for example, for an angle-dependent dimming. Finally, the other operating states relate only to different configurations of operating state B2.

In other words, the different operating states B1, B2 differ in particular in that the respective local concentration and positioning of the particles in the cavity (or inside the substrate in the case of the first alternative) is changed in order to change the transmission characteristics on the basis of the absorption by the particles.

Preferred embodiments of the various alternative embodiments are described below. The design of the first alternative is described first.

In a first alternative without a cavity, a first embodiment is implemented by configuring the first part of the electromagnetic switching mechanism as a planar electrode E1 on the first and/or second large surface and by configuring the second part of the electromagnetic switching mechanism as an electrode E2 in the form of a thin layer between the first and second large surface. The lamellae enclose an angle of between 0 ° and 30 ° with a surface normal of the first or second large face. In the first operating state B1, more than 70% of the particles are located on or near the electrode E1, respectively, and in the second operating state B2, more than 70% of the particles are located on or near the electrode E2, respectively. In an angular range of more than 30 ° with respect to the surface normal of the second large side of the substrate, this results in an angle-dependent transmission of more than 60% in the first operating state B1 and less than 10% in the second operating state B2, wherein the definitions as explained above for the first alternative apply here.

An advantage of this embodiment is that no cavities or the like are required for channeling the fluid or the scaffold matrix and the particles located therein. The final positioning of the particles after their movement essentially renders the presence of these cavities superfluous.

The electrodes E2 may be configured, for example, as strips and then arranged in intersecting regions, either in parallel or in a grid. Accordingly, the optical element is designed with respect to the angle-dependent transmission properties of one or both planes perpendicular to one another. However, it is also possible to design the design as individual planar electrodes, for example formed by surface-covered honeycombs, wherein the electrodes can be controlled jointly or else individually.

The electrodes E2 in the form of thin layers can be oriented on the one hand all at the same angle as the second large side of the substrate, in particular each substantially parallel to the perpendicular bisector of the substrate.

In contrast thereto, however, the electrode E2 can also be inclined relative to the perpendicular bisector of the substrate within an angular range of-10 ° to +10 ° ("tilt angle"), if appropriate even between-30 ° and +30 °, for example in order to produce a certain focusing effect of the thin layer relative to the observer situated in front of it. In particular in the operating state B2, this design also influences the angular dependence of the transmission of the optical element. By means of the deflection angle, the angle-dependent absorption caused by the particle absorption and particle position in dependence on the electrode shape and electrode position of the cavity is tilted by a fixed deflection angle, for example when a small transmission at a particularly steep angle is desired.

For example, the thin layer shape of electrode E2 may have a height of at least 5 μm and at most 300 μm, measured in a plane perpendicular to the second major face of the substrate. However, deviations from these typical dimensions are possible and are also within the scope of the invention.

However, in a variant of this first embodiment, a cavity-like lamella for receiving the fluid or the scaffold matrix can optionally be present, the cavity-like lamella being particularly preferably parallel to the electrode E2. Therefore, the pressure sensitivity of the optical element is reduced because the particles cannot move away from the electrode E2 when pressure is applied to the optical element.

A second embodiment of the first alternative of the invention is also configured such that all the electromagnetic switching mechanisms are designed as planar electrodes EPN on the first large surface and the second large surface, the planar electrodes having a polarity which is reversible between positive and negative. In the first operating state B1, the electrode EPN on the first large side has a positive polarity and the electrode EPN on the second large side has a negative polarity, or vice versa. Thus, more than 70% of the particles are accordingly not positioned further away from the electrode EPN than the largest quarter of the thickness of the fluid or scaffold matrix and/or in a dispersed distribution in the fluid or scaffold matrix. In the second operating state B2, the negatively polarized electrode EPN on the first large surface is disposed opposite the negatively polarized electrode EPN on the second large surface, and the positively polarized electrode EPN on the first large surface is disposed opposite the positively polarized electrode EPN on the second large surface, as viewed along the surface normal of the first large surface or the second large surface. Here, one negative polarization electrode EPN is arranged between two positive polarization electrodes EPN on each large face along the preferential direction, and one positive polarization electrode EPN is arranged between the two negative polarization electrodes EPN. In this way, more than 70% of the particles are respectively located between the electrodes EPN of the same polarity, whereby the angle-dependent transmission is greater than 60% in the first operating state B1 and less than 5% in the second operating state B2. This applies to the angular range, relative to the face normal of the second large face of the substrate and measured in a direction perpendicular to the longitudinal extension direction of the electrode EPN, preferably being +/-30 ° to +/-90 ° (i.e. respectively from-90 ° to-30 ° and at the same time from +30 ° to +90 °, but not between-30 ° and +30 °). The angular range may also vary and, instead of +/-30, also includes ranges of +/-10 to +/-90, +/-20 to +/-90, +/-45 to +/-90 or +/-25 to +/-90. The preferential direction can be oriented parallel to the second major surface of the substrate and in a horizontal position for an observer situated in front of the optical element, as already explained above.

In a third embodiment of the first alternative, further particles P are contained in the fluid or the scaffold matrix F in addition to the particles P_CWherein the other particles P are in contrast to the light-absorbing particles P_CReflect and/or scatter and/or transmit one or more wavelengths or wavelength ranges of light. All electromagnetic switching mechanisms are designed as planar electrodes EPN with a polarity that is reversible between positive and negative and are arranged on a first large surface and a second large surface. The negatively polarized electrode EPN on the first large surface is arranged opposite the negatively polarized electrode EPN on the second large surface, and the positively polarized electrode EPN on the first large surface is arranged opposite the positively polarized electrode EPN on the second large surface, as seen along the surface normal of the first large surface or the second large surface. In the preferential direction as described above, one negative polarization electrode EPN is arranged between the two positive polarization electrodes EPN on each large face, and one positive polarization electrode EPN is arranged between the two negative polarization electrodes EPN, as long as no hole having no electrode is arranged between the two positive polarization electrodes EPN or the two negative polarization electrodes EPN. The holes are periodically arranged. The particles P correspondingly have one charge polarity and the other particles P_CWith the other charge polarity.

In the two operating states B1 and B2, more than 70% of the particles P are respectively located between the positive polarization electrodes EPN and, complementary thereto, more than 70% of the other particles P_CRespectively between the negative polarized electrodes EPN, or conversely more than 70% of the particles P are respectively between the negative polarized electrodes EPN and, complementarily thereto, more than 70% of the other particles PC are respectively between the positive polarized electrodes EPN. Here, in the first operating state B1, the other particles PC are positioned between the homopolar electrodes respectively adjoining the holes, and in the second operating state B2, the particles P are positioned between the homopolar electrodes respectively adjoining the holes. In this way, it is possible to achieve an angle-dependent transmission of more than 60% in the first operating state B1 in an angular range of more than 30 ° with respect to the surface normal of the second large side of the substrate S andin the second operating state B2, less than 5%. . The angle may also vary, for example 10 °, 20 ° or 25 °; the above description of the first alternative applies analogously to the angular range.

Other particles P to be electrophoretically moved that scatter light_CCan be formed of polystyrene, melamine resin or silica having a particle size of between 20nm and 10 μm, and/or other particles P reflecting light_CCan be formed into silver nanoparticles having a particle size between 10nm and 50 nm. For such other particles P_CThe magnetophoresis of (a) must have the same paramagnetic properties. This can be achieved by introducing paramagnetic particles into the other particles P_CAnd then realized. For this purpose, for example, nickel nanoparticles, further particles P, can be used_CMay be infiltrated and/or coated with nickel nanoparticles.

In a technically equivalent variant of this third embodiment, a gel matrix F containing scattered light may be present_SThus replacing other particles P_CI.e. using cavities instead of other particles P_C. In the scattering gel matrix F_SInside, the particles P can move back and forth according to the operation state.

A first variant of the first alternative, which uses cavities combined into thin layers, comprises a substantially plate-shaped substrate S with a first large face configured as a light entry face and a second large face configured as a light exit face. This first variant also comprises a plurality of cavities embedded in the substrate S, which cavities form laminae individually or in groups according to their size, wherein each group forms a lamina. Each lamella has a longitudinal side and a narrow side extending between a first large face and a second large face, wherein the narrow side of each lamella is arranged in the region of the large faces and the longitudinal side connects the narrow sides. In this case, as a feature of this embodiment, the spaces between the lamellae contain at least one opaque material, i.e. a material which is opaque to visible light. These cavities are filled with a fluid or scaffold matrix containing at most 50% by volume, preferably at most 20% by volume, of it capable of moving in an electrophoretic or magnetophoretic mannerIts particles P_CThe further particles reflect and/or scatter light of one or more wavelengths or wavelength ranges in the range visible to the human eye, if appropriate also being transmissive and here being refractively and/or diffractively deflected. Finally, an electromagnetic switching mechanism is formed on the narrow side of the thin layer in the substrate, which electromagnetic switching mechanism in the on state generates an electromagnetic field acting in the thin layer, thereby causing the fluid or other particles P in the support matrix to flow_CAnd (4) moving. In this way, the optical element is aligned with the other particles P_CThe angle-dependent transmission of the reflected and/or scattered light of a wavelength or wavelength range is changed, the light being incident at an angle into the substrate via the light entrance face, so that the light impinges on the thin layer.

Preferably, in this first variant of the first alternative, in the first state B1, the other particles P are in a first state B1_CIs arranged near the upper narrow side of the lamella. The light which is limited in its propagation direction by the opaque material between the thin layers is thereby assisted on its upper narrow side by the other particles P_CScattered and/or reflected in a plurality of directions, light penetrates into the substrate through the light incidence side and propagates inside the thin layer. In the second state B2, other particles P_CIs arranged in the vicinity of the narrow side of the lower part of the thin layer, whereby light penetrating into the substrate S through the light incident side is due to the other particles P_CIs scattered and/or reflected, however, is limited in its propagation direction by the opaque material between the thin layers.

A second variant of this first alternative for special application scenarios firstly likewise comprises a plate-shaped substrate having a first large surface designed as a light entry surface and a second large surface designed as a light exit surface. The second variant further comprises a fluid or scaffold matrix arranged between the first and second large faces and containing up to 60% by volume of electrophoretically or magnetophoretically movable particles P which absorb or scatter light of one or more wavelengths or wavelength ranges. Where a large number of particles are present. A second variant of the first alternative further comprises a planar electromagnetic switching mechanism formed on and/or between one or both large faces of the substrate, which in the on state generates an electromagnetic field acting between the large faces to move the particles in the fluid or matrix F. Thereby, the transmittance of the optical element for light of said wavelength or wavelength range absorbed by the particles is changed, wherein the directional transmittance with respect to the surface normal of the second large face of the substrate is larger than 50% in the first operating state B1 and smaller than 50% in the second operating state B2.

The electromagnetic switching mechanism may in this case be honeycomb-shaped, cylindrical or rectangular, for example, and fill partially or substantially the entire substrate.

The second variant of the first alternative of the optical element is particularly useful for controlling perpendicular (while combined with it, but also controlling non-perpendicular) light penetration in transmission. Such application scenarios are, for example, complete or partial darkening of the glass in a passenger car, in order to avoid dazzling the driver, depending on the situation. In this case, the optical element can be configured as a plate-like plane, but can also be configured with a curved surface, for example as part of a windshield. Furthermore, the switchable mirror can be realized, for example, by means of other optical elements.

In the following, different preferred embodiments of the second alternative of the invention are discussed, which comprise chambers combined in thin layers, which chambers are also referred to below as fluid chambers.

In a preferred development of this second alternative, it is expedient if, in the first operating state B1, more than 70% of the particles are respectively located in a region of the fluid chamber on the side on which the electromagnetic switching mechanism is formed. In the second operating state B2, the switching mechanism is configured such that no static electromagnetic field is present or an alternating electromagnetic field is present, and that more than 50% of the particles are largely homogeneously distributed in the fluid chamber due to the diffusion and/or the alternating electromagnetic field. Thus, the angle-dependent transmission is greater than 60% in the first operating state B1 and less than 5% in the second operating state B2. This again applies to an angular range of more than 30 °. The angle may also vary, for example 10 °, 20 ° or 25 °, respectively, relative to the surface normal of the second large face of the substrate and measured in a direction perpendicular to the longitudinal extension direction of the lamellar fluid chambers. In the case of the second to fourth alternatives, the explanations already mentioned above regarding the angle ranges apply.

In a first variant of the second alternative for special applications, the optical element comprises a substantially plate-shaped substrate with a first large face configured as a light entry face and a second large face configured as a light exit face, and a plurality of fluid chambers embedded in the substrate, the fluid chambers each having one or more surfaces. The fluid chamber is filled with a fluid containing up to 20% by volume of particles capable of electrophoretically or magnetophoretically moving, which absorb or scatter light of one or more wavelengths or wavelength ranges. An electromagnetic switching mechanism is formed on one or more surfaces of the fluid chamber in the substrate, which electromagnetic switching mechanism generates an electromagnetic field in the fluid chamber that acts in the fluid chamber in the on-state. Thus, the particles move in the fluid, so that the transmittance of the optical element for light of the wavelength or wavelength range absorbed by the particles changes. Here, with respect to the direction of the surface normal of the second large face of the substrate, the transmittance is greater than 50% in the first operating state B1 and less than 50% in the second operating state B2.

In this case, the fluid chamber may be, for example, honeycomb-shaped, cylindrical, or rectangular, and may fill a portion of the substrate or substantially the entire substrate. This first variant of the second alternative of the optical element, like the second variant of the first alternative, is particularly useful for controlling perpendicular (while in combination with it, but also controlling non-perpendicular) light penetration in transmission. Such application scenarios are, for example, complete or partial darkening of the glass in a passenger car, in order to avoid dazzling the driver, depending on the situation. Furthermore, a dimmable mirror can be realized, for example, by means of other optical elements.

The following paragraphs describe preferred embodiments of the third and fourth alternatives.

For the particles P including the first particles P_AAnd second particles P_BFor example, in the second operating state B2, more than 70% of the first particles P_AAre correspondingly positioned on the longitudinal sides of the thin layer, and for the case of particles P designed as Janus particles, the first structure P of the particle P₁Respectively, on the longitudinal sides of the lamellae. In the first structure P₁In the case of (2), the first structure faces the longitudinal side and the second structure P₂Facing away from the longitudinal side. In contrast, in the first operating state B1, more than 70% of the second particles P_BOr second structure P of the particle P₂Respectively, positioned on the longitudinal sides of the lamina. In the second structure P₂In the case of (2), the second structure faces the longitudinal side and the first structure P₁Facing away from the longitudinal side. Thus, the angle-dependent transmission, measured in the angular range of more than 30 ° with respect to the surface normal of the second large side of the substrate and in the direction perpendicular to the longitudinal extension direction of the lamellae, is more than 60% in the first operating state B1 and less than 5% in the second operating state B2. The above description applies with respect to the angular range.

In contrast, it is also possible for the first particles P to be present in the first operating state B1_AOr a first structure P of the particle P₁Are positioned on the narrow sides of the lamellae, respectively, wherein, in the first configuration P₁In the case of (2), the first structures face the narrow side and the second structures P₂Away from the narrow side. In a second operating state B2, the second particles P_BOr a second structure P of the particle P₂Are positioned on the narrow sides of the lamellae, respectively, wherein in the second configuration P₁In the case of (2), these second structures face the narrow side and the first structure P₂Away from the narrow side. Thus, the angle-dependent transmission, measured in the angular range of more than 30 ° with respect to the surface normal of the second large side of the substrate and in the direction perpendicular to the longitudinal extension direction of the lamellae, is more than 60% in the first operating state B1 and less than 5% in the second operating state B2.

With the second to fourth alternatives, it is also applicable that, in the case where the electromagnetic switching mechanism is formed in a planar shape on only one surface of the cavity in the substrate, in the cavity in the on state, the electromagnetic switching mechanism can generate an electromagnetic field that acts within the cavity, similar to an electromagnetic field used in a so-called IPS ("in-plane switching") LCD panel.

Advantageously, for all four alternatives, including variants thereof, the electromagnetic switching mechanism is at least 50% transparent in the wavelength range visible to the human eye for light perpendicularly incident into the substrate S via the light entry face. Here, for example, the electromagnetic switching mechanism may be an indium tin oxide layer (ITO layer).

Likewise, in all four alternatives, including variants thereof, the electromagnetic switching mechanism and the fluid chamber, if present, can also be divided into a plurality of individually switchable sections, so that a local switchability between the first operating state B1 and the second operating state B2 is achieved. Local switchability means that, instead of simultaneously switching the operating states between the first and B2 in all chambers, a region with two operating states B1 and B2 is present on the optical element at the same time. Advantageously, for example when using an optical element in front of the screen, part of the image content displayed from a viewing angle of more than 30 degrees relative to the side is visible while other parts are not.

In a further advantageous embodiment, a plurality of types of particles are present in the fluid, which differ with respect to their absorption or reflection, scattering or transmission properties and/or their transport properties in the electromagnetic field. The term "transport properties" especially refers to the properties of particles in the case of (bi) electrophoresis or magnetophoresis, i.e. when transported within a field. This variant occurs in particular in the case of nanoparticles: the particle types differ here, for example, in the particle size and/or the surface function, i.e. in the zeta potential. In the case of quantum dots or colorants as particles, and if the quantum dots or colorants are fluorescent, it is preferred to also use so-called "quencher" materials, in order to avoid fluorescence as well.

If, as in the second to fourth alternative, the optical elements have cavities or lamellae, the lamellae or cavities can be oriented parallel to one another or in a grid with crossing regions. The angle-dependent transmission properties of the optical element are then designed accordingly with respect to one or two planes perpendicular to one another. In a preferred application scenario, the cavities, in particular the longitudinal sides of the cavities, are each oriented parallel to the perpendicular bisector on the substrate.

In contrast thereto, however, it is also possible to incline the cavity in an angular range ("inclination angle") of between-30 ° and +30 °, possibly even between-30 ° and +30 °, relative to the perpendicular bisector of the substrate. This design also influences the angular dependence of the transmission of the optical element, in particular in the operating state B2. By means of said offset or tilt angle, the angle-dependent absorption caused by particle absorption and particle position inside the cavity is tilted by a certain fixed offset angle, for example when a small transmission at particularly steep angles is desired. However, in particular in the restricted mode, the optimum viewing angle is also tilted from 0 ° around the tilt angle, which may be advantageous for example at a cash desk or at a screen in a vehicle.

Exemplarily, the width of the fluid chambers formed in a lamella shape in a first plane parallel to the main extension direction of the substrate is between 2 μm and 30 μm (distance of longitudinal side and longitudinal side of the fluid chamber) and is spaced apart from each other by at least 10 μm and at most 150 μm (distance of immediately adjacent longitudinal side and longitudinal side of immediately adjacent fluid chamber), respectively. Finally, the lamellar cavities R may have a height (narrow side to narrow side distance) of at least 10 μm and at most 300 μm, measured in a plane perpendicular to the first plane. However, deviations from these typical dimensions are possible and are also within the scope of the invention.

The invention is of particular interest since the optical element according to the first, second, third or fourth alternative, including its variants, is applied to a screen which can be operated in a first operating state B1 for the free-viewing mode and in a second operating state B2 for the limited-viewing mode. Such a screen comprises at least one optical element as described above and an image-reproducing unit arranged in front of or behind said at least one optical element, viewed from a viewer. The use of two optical elements, preferably of identical construction, stacked on top of one another improves the perception in operating state B2. It is particularly advantageous here if, although the optical elements are of the same type, the lamellae, cavities, etc. are arranged in the plane of one of the large faces or in a plan view of the screen, twisted relative to one another by a predetermined angle. The predetermined angle may be up to 25 ° and preferably 16 °.

The image rendering unit is for example an OLED display, LCD, SED, FED, micro LED display or VFD. Since the optical element functions independently of the type of image reproduction unit, any other type of screen can also be considered.

Furthermore, the optical element according to the invention can be used, for example, in an image reproduction unit with a backlight, for example in an LCD screen. Here, the optical element is advantageously arranged between the image reproduction panel (i.e. the LCD panel) and the backlight to switch between a first operating state B1 for the free-view mode and a second operating state B2 for the limited-view mode, since the light of the backlight is focused once (B2) and unfocused once (B1) due to the optical element. "focusing" here does not mean focusing in accordance with the type of lens, but means narrowing the emission area in accordance with the respective transmission characteristics of the optical element according to the invention.

If the above parameters are varied within certain limits, the performance of the invention remains unchanged in principle.

It is to be understood that the features mentioned above and those yet to be explained below can be used not only in the stated combination but also in other combinations or alone without departing from the scope of the present invention.

Drawings

The invention is explained in more detail below with the aid of embodiments with reference to the drawings, which likewise disclose important features of the invention. These examples are for illustrative purposes only and should not be construed as limiting. For example, descriptions of embodiments having multiple elements or components should not be construed as indicating that all such elements or components are necessary for implementation. Rather, other embodiments may include alternative elements and components, fewer elements or components, or additional elements or components. Elements or components of different embodiments may be combined with each other, unless otherwise indicated. The modifications and variations described for one of the embodiments may also be applied to other embodiments. To avoid repetitions, elements that are identical or correspond to one another are denoted by the same reference numerals in the different figures and are not explained many times. Wherein:

fig. 1 shows a schematic representation of an optical element according to a first alternative in a first embodiment in an operating state B1;

fig. 2 shows a schematic representation of an optical element according to a first alternative in a first embodiment in an operating state B2;

fig. 3 shows a schematic representation of an optical element according to a first alternative in a second embodiment in an operating state B2;

fig. 4 shows a schematic representation of an optical element according to a first alternative in a second embodiment in an operating state B1 in a first variant;

fig. 5 shows a schematic representation of an optical element according to the first alternative in a second embodiment in an operating state B1 in a second variant;

fig. 6 shows a schematic representation of an optical element according to a first alternative in a third embodiment in an operating state B1;

fig. 7 shows a schematic representation of an optical element according to a first alternative in a third embodiment in an operating state B2;

fig. 8 shows a schematic representation of an optical element in a first variant of the first alternative in an operating state B1;

fig. 9 shows a schematic representation of an optical element in a first variant of the first alternative in an operating state B2;

fig. 10 shows a schematic diagram of an exemplary effect of the optical element of the first alternative and shows variants with regard to transmission at different angles in two operating states B1 and B2;

fig. 11 shows a schematic diagram of an optical element in a second variant of the first alternative in a sectional view;

fig. 12 shows a schematic diagram of the optical element of fig. 11 in a top view, wherein the optical element is in an operating state B1;

fig. 13 shows a schematic diagram of the optical element from fig. 11 in a top view, wherein the optical element is in an operating state B2;

fig. 14 shows a schematic diagram of an optical element according to a second alternative in an operating state B1;

fig. 15 shows a schematic diagram of the optical element of fig. 14 in an operating state B2 according to a second alternative;

fig. 16 shows a schematic representation of the optical element from fig. 14 in a top view, wherein the two operating states B1 and B2 are switched on locally differently and the fluid chambers are arranged parallel to one another;

fig. 17 shows a schematic representation of the optical element from fig. 14 in a top view, wherein the two operating states B1 and B2 are switched on locally differently and the fluid chambers are arranged crosswise to one another;

fig. 18 shows a schematic diagram of an optical element in a first variant of the second alternative in a sectional view;

FIG. 19 shows a schematic diagram of two different particle types within a capsule in conjunction with a third alternative of an optical element;

fig. 20 shows a first design of a Janus particle in combination with a fourth alternative of an optical element;

fig. 21 shows a second design of a Janus particle in combination with a fourth alternative of an optical element;

fig. 22 shows a third design of a Janus particle in combination with a fourth alternative of an optical element;

fig. 23 shows a schematic diagram of a first embodiment of an optical element according to a third or fourth alternative in a sectional view in an operating state B1;

fig. 24 shows a schematic diagram of a first embodiment of an optical element according to a third or fourth alternative in a sectional view in an operating state B2;

fig. 25 shows a schematic representation of a second embodiment of an optical element according to the third or fourth alternative in a sectional view in an operating state B1, an

Fig. 26 shows a schematic representation of a second embodiment of an optical element according to the third or fourth alternative in a sectional view in an operating state B2.

Detailed Description

The figures are not drawn to scale and merely represent schematic diagrams. Furthermore, for the sake of greater clarity, only a small selection of electrodes, beams, particles, etc. are generally shown, respectively, although in practice a considerable number of these electrodes, beams, particles, etc. may be present. Four different alternatives are described below, which relate in particular to the properties of the substrate itself and the properties of the particles and have a commonality which is not repeated in detail for each alternative.

The schematic diagram of the first optical element according to the first alternative in the first embodiment in the operating state B1 is therefore depicted in fig. 1 and in the operating state B2 is depicted in fig. 2. The optical element comprises a substantially plate-shaped substrate S having a first large face configured as a light entrance face and a second large face configured as a light exit face. The optical element further comprises a fluid or scaffold matrix F arranged between the first and second large faces and containing up to 60% by volume of particles P that are electrophoretically or magnetophoretically movable, wherein there are a plurality of particles P that absorb light of one or more wavelengths or wavelength ranges. On one or both large faces and/or between the large faces in the substrate S, a planar electromagnetic switching mechanism E1, E2 is configured, which in the on state generates an electromagnetic field acting between the large faces, thereby moving the particles P in the fluid or the support matrix F. As a result, the angular transmittance of the optical element with respect to light of the wavelength or wavelength range absorbed by the particles P changes, and the light is incident on the substrate S serving as the optical filter via the light incident surface. Further substrates, not labeled here, are usually arranged above and below the substrate, so that the light entry surface forms a boundary surface between the further substrate arranged above and the cavity or cavities inserted into the substrate S.

In the case of the scaffold matrix F, the scaffold matrix is, for example, configured as a polymer matrix, preferably as a gel matrix. The fluid F may be polar or non-polar. Furthermore, the fluid may consist of, for example, water, oil, toluene or formaldehyde, or may be mixed with an electrolyte. This applies reasonably to all and also the embodiments of the optical element in its alternative described below.

The plate-shaped substrate S is constructed in such a way that the first large face of the light entry face is usually situated on the rear side of the substrate S from the viewpoint of the observer and, depending on the application of the optical element, for example adjacent to an image reproduction device, a light source or an air volume, can consist of glass or polymer, for example. Then, light is incident from the last-mentioned object into the substrate through the light incident surface.

As shown in fig. 1, the first part of the electromagnetic switching mechanism is configured as a planar electrode E1 on the first large side, and the second part of the electromagnetic switching mechanism is configured as an electrode E2 in the form of a thin layer between the first large side and the second large side. The lamellae usually enclose an angle of between 0 ° and 30 °, in this case 0 °, with the surface normal of the first or second large surface. In the first operating state B1, more than 70% of the particles P were located on the electrode E1, respectively. Thus, as is indicated in fig. 1 by means of arrows, light incident on the incident side (lower edge in the drawing) can pass through the optical element as unhindered as possible within the propagation angle. In this case, in the first operating state B1, the angle-dependent transmission is greater than 60% in an angular range of greater than 30 ° with respect to the surface normal of the second large side of the substrate S. For example, the angular range with respect to the plane normal, i.e., the plane perpendicular to the second major surface of the substrate S, may be measured in a plane containing the perpendicular bisector as the plane normal, and disposed horizontally from the viewpoint of the observer.

In the second operating state B2 shown in fig. 2, more than 70% of the particles P are located at or near the electrodes E2, respectively, such that the angle-dependent transmission is less than 10% over an angle range of more than 30 ° with respect to the surface normal of the second large face of the substrate. This is also illustrated by the arrows. Some of the transmission ends at the particle P, which contributes to the absorption. An advantage of this design is that no cavities or the like are required for channeling the fluid or the scaffold matrix F and the particles P located therein. The final positioning of the particles P on the electrodes E1 or E2 after the movement of the particles substantially renders the presence of such cavities superfluous.

The shape of the thin layer for electrode E2 may be parallel or grid-like with intersecting regions. The angle-dependent transmission properties of the optical element with respect to one or two planes perpendicular to one another are then designed accordingly. The electrodes E2 in the form of thin layers can be oriented on the one hand all at the same angle as the second large side of the substrate S, in particular each substantially parallel — perpendicular to the perpendicular bisector of the substrate S. In contrast, it is also possible to tilt the cavity relative to the perpendicular to the substrate in an angular range ("tilt angle") of-10 ° to +10 °, if appropriate even between-30 ° and +30 °, for example in order to produce a focusing effect of the thin layer relative to the observer situated in front. In particular in the operating state B2, this design also influences the angular dependence of the transmission of the optical element. For example, when it is desired to transmit less at a particularly steep angle, the particle absorption and the angle-dependent absorption caused by the particle position and the electrode shape of the cavity are tilted by a fixed offset angle by the offset angle.

Illustratively, the thin-layer shape of the electrode E2 may have a height of at least 5 μm and at most 300 μm, measured in a plane perpendicular to the second large face of the substrate S. The width of electrode E1 may have similar dimensions.

The following embodiments, in particular the embodiments describing the structure of the substrate itself and the composition of the particles, apply not only to the first alternative but also to the second, third or fourth alternative described further below. The one or more wavelengths or wavelength ranges at which the particles P, which can be moved electrophoretically or magnetophoretically, absorb light are preferably situated in the visible spectrum and particularly preferably completely cover this visible spectrum.

The first and second large faces of the plate-like substrate S are preferably arranged parallel to each other. However, in a particular design, for example when a particular angle-dependent transmission of the optical element can be achieved, the first and second large faces can also be arranged non-parallel to one another, for example wedge-shaped to one another within a defined angle of at most 20 degrees.

The particles P may be nanoparticles, quantum dots and/or colorantsThe seeds have a spatial extension of at most 200nm to less than at most 20 nm. Spatial extension here means the maximum extension or hydrodynamic radius in three-dimensional space, depending on which is greater. Thus, for spherical particles, it is the diameter. In the case of chain-like particles, it is then the maximum possible distance that two points on the surface of the particle can have from each other, respectively. The particles P may be BPQD (black phosphorus quantum dots), lead sulfide (PbS), CdSeSe quantum dots, azo colorants and/or metal oxide particles, preferably made of chromium (IV) oxide or Fe₂O₃Formed and in each case having a size of between 2nm and 50nm, inclusive.

Alternatively, an embodiment as a paramagnetic body is also possible, for example as a sphere with a diameter of at least 100nm made of a paramagnetic or diamagnetic carrier material (preferably melamine resin or polystyrene) with a relative permeability between 0.5 and 2, wherein the relative permeability is preferably close to 1 or should be 1. Then, for example, by paramagnetic or superparamagnetic nanoparticles having a relative permeability of more than 10, preferably Fe₂O₃The body is coated with nanoparticles or the support material is infiltrated by these nanoparticles. Surface functionalization with higher zeta potentials is also advantageous.

The particles P are charged and the electromagnetic switching mechanism is configured as an electrode for generating a static or dynamic electric field, or the particles are paramagnetic or superparamagnetic and the electromagnetic switching mechanism is configured as a conductive coating for generating a static or dynamic magnetic field, such that said electrophoretic or magnetophoretic particles P move in the fluid or scaffold matrix F in the electric or magnetic field.

Depending on the configuration of the particles, the electromagnetic switching mechanism is configured as an electrode for generating a static or dynamic electric field, or as a conductive coating for generating a static or dynamic magnetic field.

Fig. 3 to 5 show a second embodiment of the optical element according to the first alternative. In the optical element, all the electromagnetic switching mechanisms are configured as planar electrodes EPN on the first and second large faces, the planar electrodes having a polarity that is reversible between positive and negative. In the first operating state B1, the electrode EPN on the first large face has a positive polarity and the electrode EPN on the second large face has a negative polarity, or the electrode EPN on the first large face has a negative polarity and the electrode EPN on the second large face has a positive polarity. Thus, more than 70% of the particles P are each no more than a maximum of one quarter of the thickness of the fluid or matrix F from the respective electrode EPN (as shown in fig. 5) and/or are positioned dispersed throughout the fluid or scaffolding matrix F (as shown in fig. 4). The arrows indicate the selected rays of light which prove to be possible here through the substrate at a large range of angles. In the first operating state B1, the angle-dependent transmission is therefore greater than 60% in an angular range of greater than 30 ° with respect to the surface normal of the substrate S, wherein the angular range can also vary.

Fig. 3 shows the optical element in an operating state B2. In general, in this embodiment, the negatively polarized electrode EPN on the first large face is placed opposite the negatively polarized electrode EPN on the second large face, and the positively polarized electrode EPN on the first large face is placed opposite the positively polarized electrode EPN on the second large face, as viewed along the surface normal of the first large face or the second large face. Here, one negative polarized electrode EPN is arranged between two positive polarized electrodes EPN and one positive polarized electrode EPN is arranged between two negative polarized electrodes EPN in the preferential direction on each large face, so that 70% or more of the first particles (P) are present_A) Respectively, between identically polarized electrodes EPN. The angle-dependent transmission is therefore less than 5% in the angular range of more than 30 ° with respect to the surface normal of the second large side of the substrate S, and the preferential direction can be oriented here, for example, parallel to the second large side of the substrate S and at a horizontal position for an observer arranged in front of the optical element.

Fig. 6 shows a schematic representation of an optical element according to the first alternative in a third embodiment in an operating state B1, and fig. 7 shows a schematic representation in an operating state B2. In addition to the absorbent particles P, further particles P are contained in the fluid or scaffold matrix F_CWherein other particles P_CReflection and/or scattering and-Or transmit one or more wavelengths or wavelength ranges of light. All electromagnetic switching mechanisms are arranged here as planar electrodes EPN on the first large face and the second large face, which have a polarity that is reversible between positive and negative, wherein, viewed along the surface normal of the first large face or the second large face, the negatively polarized electrode EPN on the first large face is placed opposite the negatively polarized electrode EPN on the second large face, the positively polarized electrode EPN on the first large face is placed opposite the positively polarized electrode EPN on the second large face, and one negatively polarized electrode EPN is arranged between two positively polarized electrodes EPN on each large face in the preferential direction as already defined, and one positively polarized electrode EPN is arranged between two negatively polarized electrodes EPN, provided that no electrode-free cavities are arranged between two positively polarized electrodes EPN or two negatively polarized electrodes EPN, wherein the cavities are arranged periodically. The particles P correspondingly have one charge polarity, while the other particles P_CWith the other charge polarity.

In the two operating states B1 and B2, more than 70% of the particles P are respectively located between the positive polarization electrodes EPN and, complementary thereto, more than 70% of the other particles P_CRespectively between the negative polarized electrodes EPN, or more than 70% of the particles P are respectively between the negative polarized electrodes EPN and, complementary thereto, more than 70% of the other particles P_CRespectively located between the positive polarization electrodes EPN. In this case, in a first operating state B1 (see fig. 6), further particles P_CAre respectively positioned between the homopolar electrodes respectively adjacent to the holes, and in the second operating state B2 (see fig. 7) the particles P are respectively positioned between the homopolar electrodes respectively adjacent to the holes. In an angular range of more than 30 ° with respect to the surface normal of the second large side of the substrate S, the angle-dependent transmission is more than 60% in the first operating state B1 and less than 5% in the second operating state B2.

The light incident on the light-incident side of the substrate S can now be in particular at the locations where no particles P are present due to the holes and where further particles P are arranged_CIs (almost) propagated unimpeded. In fig. 6 and 7, light beams illustrating the function are again exemplarily depicted.

Scattering lightOf other particles P to be electrophoretically moved_CMay be formed of polystyrene, melamine resin or silica having a particle size of between 20nm and 10 μm. Other particles P reflecting light_CCan be formed into silver nanoparticles having a particle size between 10nm and 50 nm. For such other particles P_CThe magnetophoresis of (a) must have the same paramagnetic properties. This may be achieved by binding paramagnetic moieties of the particles to other particles P_CTo be implemented in (1). For this purpose, for example, nickel nanoparticles can be used.

Furthermore, it is contemplated herein that at least one electrode of the electrode EPN (e.g., the respective intermediate electrode) may advantageously be designed to be downwardly reflective in order to improve the power and efficiency of the optical structure.

Fig. 8 shows a schematic diagram of the optical element in a first variant of the first alternative in an operating state B1, and fig. 9 shows a schematic diagram of the optical element in an operating state B2. The optical element also comprises a substantially plate-shaped substrate S having a first large face configured as a light entrance face and a second large face configured as a light exit face. The optical element also comprises a plurality of cavities K embedded in the substrate S, which cavities form lamellae individually or in groups, depending on their size, wherein each group forms a lamella. Each lamella has a longitudinal side and a narrow side extending between a first large face and a second large face, wherein the narrow side of each lamella is arranged in the region of the large faces and the longitudinal side connects the narrow sides, and the space between the lamellae contains at least one opaque (i.e. opaque to visible light) material M. The cavity is filled with a fluid or scaffold matrix F containing at most 50% by volume, preferably at most 20% by volume, of further particles P that move electrophoretically or magnetophoretically_CThe further particles reflect and/or scatter light of one or more wavelengths or wavelength ranges in the range visible to the human eye, if appropriate also being transmissive and here being refractively and/or diffractively deflected. Planar electromagnetic switching means EPN are formed in or on the substrate S on the narrow sides of the thin layer or the chamber K, which electromagnetic switching means in the on state generate an electromagnetic field acting in the thin layer, as a result of which further particles P are caused to move_CIn the fluid or in the scaffoldMoves in the mass F. Thereby, the optical element is aligned with the other particles P_CThe angle-dependent transmission of the reflected and/or scattered wavelength or wavelength range of light changes, and the further particles enter the substrate S via the light entrance face at an angle such that the light impinges on the thin layer.

In this case, in a first operating state B1 shown in fig. 8, at least 70% of the other particles P are present_CArranged near the upper narrow side of the lamella or cavity K. The light which is limited in its propagation direction by the opaque material M between the thin layers is thus limited on the upper narrow side by means of the further particles P_CScattered and/or reflected in a plurality of directions, the light penetrating into the substrate S through the light incident side and propagating inside the thin layer.

The dashed arrows indicate that a particular ray of light is absorbed within a definable angular range by the opaque material M, which may be, for example, melamine resin. In the second state B2 shown in FIG. 9, at least 70% of the other particles P are_CThe lower narrow side of the thin layer is arranged in the vicinity of the narrow side, whereby the light penetrating into the substrate S through the light incident side is due to the other particles P_CBut is nevertheless limited in its propagation direction by the opaque material M between the thin layers.

For all the preceding embodiments of the element and for all the subsequent embodiments (except for the embodiments shown in fig. 11 to 13 and 18), fig. 10 shows a schematic diagram of exemplary effects in the respective two operating states B1 and B2 with regard to transmission at different angles, in particular when applied before the image reproduction device. For the sake of simplicity, normalized values are referred to here. The dashed line corresponds to the running state B2 ("private mode") and the solid line corresponds to the running state B1 ("public mode"). The ordinate here represents the relative brightness ("relative brightness") and the abscissa represents the measured angle (horizontal, i.e. arranged in a direction perpendicular to the longitudinal extent of the lamellae) ("viewing angle"). The measurement angle here covers the above-mentioned angle range, i.e. the surface normal of the second major surface of the substrate S is referred to and measured in a direction perpendicular to the longitudinal extension direction of the lamellae. For a display mounted in a car, this may be an angle in the horizontal plane, for example. The different angle-dependent transmission of the optical element for the light of the wavelength or wavelength range absorbed by the particles P in the two operating states B1 and B2 is responsible for making the image reproduction apparatus visible from all horizontal viewing angles in the operating state B1, whereas viewing from only a significantly limited range of angles is possible in the operating state B2, as shown in fig. 10.

Fig. 11 shows a schematic diagram of an optical element in a second variant of the first alternative in a sectional view. The optical element comprises a plate-shaped substrate S having a first large face configured as a light entrance face and a second large face configured as a light exit face, and a fluid or carrier matrix F arranged between the first large face and the second large face and containing up to 60% by volume of particles P movable electrophoretically or magnetophoretically, wherein a plurality of particles P are present which absorb light of one or more wavelengths or wavelength ranges. On one or both large faces and/or between the large faces in the substrate S, a planar electromagnetic switching mechanism E1, E2 is constructed, which in the on state generates an electromagnetic field acting between the large faces, thereby moving the particles P in the fluid or the support matrix F. Thereby, the transmittance of the optical element for light of the wavelength or wavelength range absorbed by the particles P changes, wherein with respect to the direction of the surface normal of the second large face of the substrate S the transmittance is greater than 50% in the first operating state B1 and less than 50% in the second operating state B2.

The electromagnetic switching mechanism E1 or E2 may in this case, for example, be honeycomb-shaped, cylindrical or rectangular and fill a part of or the entire large surface of the substrate S, wherein the entire large surface may also be covered by a correspondingly sized individual electrode (e.g. E2). For this purpose, fig. 12 shows a schematic representation of the optical element from fig. 11 in a top view, with the optical element in an operating state B1 and fig. 13 showing a corresponding operating state B2. In the operating state B1 shown in fig. 12, the particles P are respectively concentrated on the electrodes E1 of the switching mechanism due to the applied electrostatic field, so that the transmittance of the optical element in the vertical direction reaches a maximum. In contrast, in the operating state B2 shown in FIG. 13, the particles P_AThe transmittance of the optical element in the vertical direction is minimized due to the applied electrostatic field being concentrated on the electrodes E2 of the switching mechanism, respectively. Preferably, the transmission changes from above 80% in the operating state B1 to less than 10% in the operating state B2, which can be made without problems by a corresponding selection of the parameters.

In a second variant of the first alternative, this design of the optical element is particularly suitable for controlling the transmission of light in a perpendicular direction (but also in combination therewith non-perpendicular directions) in relation to the transmission. An application for this is, for example, the complete or partial dimming of the glass in a passenger car, in order to avoid dazzling the driver, depending on the situation. Furthermore, the switchable mirror can also be realized by other optical elements, for example.

In the case of the above-described optical element, at least in basic embodiments, without chambers (also referred to as fluid chambers) which form thin layers individually or in combination, this is true in the embodiments of the second to fourth alternatives described below.

Fig. 14 shows a schematic diagram of an optical element according to a second alternative in an operating state B1, and fig. 15 shows the optical element in an operating state B2.

The optical element shown in fig. 14 and 15 comprises a substantially plate-shaped substrate S with a first large surface 3 configured as a light entry surface and a second large surface 4 configured as a light exit surface, and a plurality of thin-layer-shaped fluid chambers embedded in the substrate S, which have a longitudinal side and a narrow side extending between the first large surface 3 and the second large surface 4, wherein the narrow side is arranged in the region of the large surfaces 3, 4 and the longitudinal side connects the narrow sides. This or a fluid chamber is filled with a fluid F, wherein the fluid contains at most 50% by volume, preferably at most 20% by volume, of particles P capable of electrophoretically or magnetophoretically moving, which particles P absorb light of one or more wavelengths or wavelength ranges. The height of the thin layer should be effective to limit the amount of particles, i.e. to 50% or 20% of the height of the cavity. However, too high a concentration of particles may reduce the switchability due to instability effects and shielding effects. The electromagnetic switching mechanism 2 is formed in a planar shape on one or more side surfaces of the fluid chamber R in the substrate S. In the on state, the electromagnetic switching mechanism generates an electromagnetic field acting in the fluid chamber R, thereby moving the particles P in the fluid F. Thereby, the angle-dependent transmittance of the optical element for light of the wavelength or wavelength range absorbed by the particles P changes, and the light is incident into the substrate S via the light incident surface 3 at an angle such that the light impinges on the fluid chamber R.

The first large side 3 and the second large side 4 of the plate-shaped substrate S are preferably arranged parallel to one another. However, in a particular embodiment, for example when a particularly angle-dependent transmission of the optical elements is realized, they may also be arranged non-parallel to each other, for example wedge-shaped to each other within a defined angle of at most 20 degrees.

The first large side 3 of the plate-shaped substrate S, which is formed as a light incidence surface, is usually situated on the rear side of the substrate S from the viewpoint of the observer and, depending on the application scenario of the optical element, for example adjoins an image reproduction device (indicated by reference numeral 1 in the drawing), a light source or an air volume. Then, light is incident into the substrate from the last-mentioned object through the light incident surface 3.

In this example, a lamellar-shaped fluid chamber R having a longitudinal side and a narrow side extending between a first large face 3 and a second large face 4 has a rectangular parallelepiped shape and is oriented parallel to the large faces 3, 4. Accordingly, the remaining outer side surfaces are two surfaces, which are not embodied as narrow side and longitudinal side.

It is also clear that the fluid chamber R at least partially protrudes on one or both large faces 3 and/or 4 of the substrate S, as shown in fig. 14 and 15. Here, the electrophoretically or magnetophoretically movable particles P absorb light at one or more wavelengths or wavelength ranges in the visible spectrum and cover the visible spectrum substantially completely.

The electromagnetic switching mechanism 2, which is formed flat on one or more sides of the fluid chamber R in the substrate S, is arranged, for example, on the narrow side of the respective fluid chamber R, as shown in fig. 14 and 15. The particles P are, for example, nanoparticles, quantum dots and/or colorants, as has already been described a number of times before. As fluid, for example, water mixed with 10% by volume of ferrofluid and electrolyte can be used.

Further, the particles P are charged and the electromagnetic switching mechanism 2 is configured as an electrode for generating a static electric field or a dynamic electric field, so that the electromagnetic particles P in the electric field move in the fluid F. The corresponding electric field lines are then formed parallel, for example in the center of the fluid chamber R, and are more likely to show deviations from parallelism at the edges.

By means of the electromagnetic switching mechanism 2, which is designed, for example, as a transparent electrode, and the control circuit, at least two operating states are defined, wherein in the first operating state B1 the angle-dependent transmission is greater than 50% and in the second operating state B2 less than 50%. This applies to an angular range of more than 30 ° (which may also vary, for example 10 °, 20 ° or 25 °), measured relative to the surface normal of the second large face of the substrate and in a direction perpendicular to the longitudinal extension direction of the lamellar fluid chambers R. The longitudinal extension direction is defined here by a straight line connecting the surface center points of the two outer sides of each fluid chamber R. For the operating state B1, an electrostatic field is generated by the switching mechanism 2 so as to move the particles P, while for the operating state B2 no electric field is applied so as to distribute the particles P within the fluid chamber R by diffusion.

In a preferred refinement of this embodiment, it is expedient for more than 70% of the particles P to be positioned in a region on the side of the fluid chambers R1, R2, …, respectively, on which side the electromagnetic switching mechanism 2 is formed, as a result of the electrostatic field, in the first operating state B1, and for more than 50% of the particles P (mainly as a result of the diffuse and/or alternating electromagnetic field) to be distributed predominantly uniformly in the fluid chambers R, in the second operating state B2, in which the switching mechanism 2 is configured such that no electrostatic magnetic field or temporally alternating electromagnetic field is present, such that the angle-dependent transmission is more than 60% in the first operating state B1 and less than 5% in the second operating state B2. This again applies to an angular range of more than 30 ° (which may also vary, for example, 10 °, 20 ° or 25 °), measured with respect to the surface normal of the second large face of the substrate and in a direction perpendicular to the longitudinal extension direction of the lamellar fluid chambers. The different operating states B1, B2, … therefore differ, inter alia, in that the respective local concentration and position of the particles P in the fluid chamber is changed in order to change the transmission characteristic as a result of absorption by the particles.

Advantageously, the electromagnetic switching mechanism 2 is transparent to at least 50%, preferably more than 80%, of the light in the visible wavelength range which is perpendicularly incident into the substrate S via the light entrance face. This also applies to all other designs.

Furthermore, the electromagnetic switching mechanism (e.g., the fluid chamber R) can be divided into a plurality of individually switchable sections, so that a local switchability between the first operating state B1 and the second operating state B2 is achieved. Here, the local switchability means that instead of simultaneously switching the operating states between B1 and B2 in all fluid chambers, a region with two operating states B1 and B2 is present on the optical element at the same time. Advantageously, for example when using optical elements in front of the screen, the image content displayed by parts is visible and other parts are not visible from viewing angles exceeding 30 degrees relative to the side.

This configuration is shown in fig. 16. The schematic diagram shows a plan view of an optical element according to a second alternative, in which the partial regions are differently connected in the operating states B1 and B2, and the fluid chambers are arranged parallel to one another. The fluid chamber R shown bright here is in the operating state B1, while the fluid chamber shown dark is in the operating state B2.

The fluid chambers R may be oriented parallel to each other as shown in fig. 16, or may be oriented in a grid-like manner with intersecting regions as shown in fig. 17. The angle-dependent transmission properties of the optical element with respect to one or two planes perpendicular to one another are then designed accordingly. Fig. 17 shows a top view of an optical element according to the invention according to a second alternative, in which locally different operating states B1 and B2 are switched in, and the fluid chambers are arranged crossing each other in a grid. The fluid chamber R shown in bright is in the operating state B1, while the fluid chamber shown in dark is in the operating state B2. In order to suppress the Moire effect, the fluid chambers (R) or generally the lamellae can also be arranged non-periodically, i.e. with a variable spacing from one another. Alternatively or additionally, less regularly shaped cavities, for example curved cavities or curved lamellae, are also conceivable.

It is also possible to use a plurality of types of particles which differ in their absorption properties and/or their transport properties in the electromagnetic field. The "transport properties" mean in particular the properties of the particles P in the corresponding electrophoretic phenomena (transport in the field). This variant occurs in particular in the case of nanoparticles: the particle types here differ, for example, in the particle size and/or the surface function, i.e. the zeta potential. In the case of quantum dots or colorants as particles, and if the particles are fluorescent, it is preferred to also use so-called "quencher" materials, in order to avoid fluorescence as well.

Typically, the fluid chambers (particularly the longitudinal sides thereof) are each oriented substantially parallel to the perpendicular bisector on the substrate S. In contrast to this, however, the fluid chamber R can also be inclined relative to the perpendicular bisector of the substrate S in an angular range ("inclination angle") of-10 ° to +10 °, optionally even in an angular range between-30 ° and +30 °. This design also affects the angular dependence of the transmission of the optical element, particularly (but not exclusively) in the operating state B2. By the mentioned skew or inclination angle, the angle-dependent absorption caused by particle absorption and particle position inside the fluid chamber is inclined at a fixed offset angle, for example when a small transmission is desired in particularly steep angles.

Exemplarily, the lamellar fluid chambers R may be about 10 μm wide (distance of longitudinal side from longitudinal side of the fluid chamber R) and each be 50 μm away from each other (distance of longitudinal side from respective immediately adjacent longitudinal side of immediately adjacent fluid chambers R) in a first plane parallel to the main extension direction of the substrate S. Finally, the fluid chamber R in the form of a lamella may have a height (distance between the narrow side and the narrow side) of about 40 μm, measured in a second plane perpendicular to the first plane.

All alternatives of optical elements (including the aforementioned and subsequent alternatives) can preferably be used with a screen that can be operated in the first operating state B1 for the free-viewing mode and in the second operating state B2 for the limited-viewing mode. Such a screen comprises, in addition to the optical element, an image-reproducing unit arranged behind or in front of the optical element for observation by an observer. The image reproduction unit 1 is, for example, an OLED display, an LCD display, an SED display, an FED display, a micro LED display or a VFD display. Since the optical element functions independently of the type of image reproduction unit 1, any other screen type can also be considered. Furthermore, the optical element as described above or below may also be used in an image rendering unit with a backlight, for example in an LCD screen. Here, it is advantageous that the optical element is arranged between the image reproduction panel (i.e. the LCD panel) and the backlight to switch between a first operating state B1 for the free-view mode and a second operating state B2 for the limited-view mode, since the light of the backlight is focused once (in operating state B2) and unfocused once (in operating state B1) due to the optical element.

The light emitted by the image reconstruction unit 1 enters the optical element through the light entry surface, i.e. the large surface 3, and is then influenced in its propagation in the optical element as a function of the operating state, in order then to continue from the optical element through the large surface 4 again to one or more observers. The effect has been described in connection with fig. 10 for a first alternative of the optical element, the description made in fig. 10 applying here analogously.

Further, it should be noted that if the electromagnetic switching mechanism 2 is formed only on a corresponding one surface of the fluid chamber R in the substrate S, in the energized state, the electromagnetic switching mechanism 2 can generate an electromagnetic field acting within the fluid chamber R in the fluid chamber R, which is similar to an electromagnetic field used in a so-called IPS ("in-plane switching") LCD panel. This also applies to the alternatives described further below.

Fig. 18 shows a first variant of an optical element according to the second alternative in an operating state B1. This variant comprises a substantially plate-shaped substrate S with a first large face 2 configured as a light entry face and a second large face configured as a light exit face, and a plurality of fluid chambers R embedded in the substrate S, which fluid chambers R each have one or more surfaces. The fluid chamber R is filled with a fluid F containing up to 20% by volume of particles P capable of electrophoretic or magnetophoretic movement, which absorb light of one or more wavelengths or wavelength ranges. A planar electromagnetic switching mechanism is formed at one or more surfaces of the fluid chamber R in the substrate S, which planar electromagnetic switching mechanism generates an electromagnetic field in the fluid chamber R that acts inside the fluid chamber in the on state, thereby moving the particles P in the fluid such that the transmittance of the optical element for light of the wavelength or wavelength range absorbed by the particles P changes, wherein in the first operating state B1 the transmittance is greater than 50% in relation to the direction of the surface normal of the second large surface of the substrate S and in the second operating state B2 the transmittance is less than 50%. Preferably, the transmission changes from more than 80% in the operating state B1 to less than 10% in the operating state B2, which can be easily achieved by a corresponding selection of the parameters within the scope of the invention.

In this case, the fluid chamber R is, for example, honeycomb-shaped, and substantially fills the substrate S. In the operating state B1 shown in fig. 18, the particles P are respectively collected on the electrodes of the switching mechanism 2 as a result of the applied electrostatic field, so that the transmission of the optical element in the vertical direction reaches a maximum. In plan view, the optical element is identical to the optical element shown in fig. 12 and 13 with the same type of operating state, with the difference that a fluid chamber is present here.

In particular, the optical element can also be used to control the transmission of light in a perpendicular (combined with a perpendicular but also non-perpendicular) direction in relation to the transmission. An application for this is, for example, the complete or partial dimming of the glass in a passenger car, in order to avoid dazzling the driver, depending on the situation.

The following describes the design of the optical element according to the third and fourth alternative. For this purpose, fig. 19 shows a schematic diagram of two different particle types for use in an optical element according to a third alternative. The particle type comprises, on the one hand, first particles P of a first type of particles_AThe first type of particles absorbing one or more wavelengths or waves in the range visible to the human eyeLong range light. In addition, the particle type further includes second particles P of a second type of particles_BThe second type of particles reflects and/or scatters light of one or more wavelengths or wavelength ranges in the range visible to the human eye, wherein the two types of various particles are preferably located within a capsule, here indicated by a circle.

In connection with the fourth alternative, fig. 20 shows a schematic diagram of a first preferred design of a so-called Janus particle. The Janus particles respectively have at least one first structure P₁And a first region different from the first structure P₁With a second structure P₂Wherein the first structure P₁Absorbs light of one or more wavelengths or wavelength ranges, and a second structure P₂Reflect and/or scatter light of one or more wavelengths or wavelength ranges.

Fig. 21 shows a schematic diagram of a second embodiment of a Janus particle in combination with a fourth alternative, wherein the second region is significantly larger than the first region. FIG. 22 shows a schematic diagram of a third embodiment of a Janus particle, likewise in combination with a fourth alternative, in which exactly three regions are present, having a first structure P₁By having a second structure P₂Is divided. Other design possibilities are also conceivable, for example having a third structure P₃The third structure has further optical properties (e.g. with respect to P)₂Reduced scattering or reflection).

Fig. 23 shows a sectional view of a first embodiment of an optical element according to the third or fourth alternative in an operating state B1, and fig. 24 shows a sectional view of the same optical element in an operating state B2. The circles indicate capsule bodies or Janus particles filled with the first type of particles and the second type of particles. The optical element comprises a substantially plate-shaped substrate S with a first large face configured as a light entry face and a second large face configured as a light exit face, and a plurality of cavities R embedded in the substrate S, which cavities R form lamellae individually or in groups, each group forming one lamella, depending on their size. Each lamella has a longitudinal side and a narrow side extending between a first large face and a second large face, wherein the narrow side of each lamella is arranged in the region of the large faces and the longitudinal side connects the narrow sides. The cavity R is filled with a fluid or scaffold matrix F containing up to 95% by volume of particles P capable of moving electrophoretically or magnetophoretically.

In a third alternative, in the first design, the particles comprise at least first particles P of a first type of particles_AAnd second particles P of a second type of particles_BThe first type of particles absorbs light of one or more wavelengths or wavelength ranges within the region visible to the human eye and the second type of particles reflects and/or scatters light of one or more wavelengths or wavelength ranges within the region visible to the human eye. If only one of the two types of particles is present, in a second design variant of the third alternative the fluid or the scaffold matrix F itself effects the first particles P_AOr the second particles P are realized_BThe function of (1). The particles P then comprise only the respective other particles P_BOr P_AThe other particles are not realized by the fluid or the scaffold matrix F.

In a fourth alternative, the particles P are embodied as Janus particles and each have at least one first structure P₁And a second structure P different from the first region₂Wherein the first structure P₁Absorbs light of one or more wavelengths or wavelength ranges, and a second structure P₂Reflect and/or scatter light of one or more wavelengths or wavelength ranges.

The optical element according to the third or fourth alternative further comprises a planar electromagnetic switching mechanism formed on one or more sides of the thin layer in the substrate S, which electromagnetic switching mechanism in the on state generates an electromagnetic field acting in the thin layer, whereby the particles P move in the fluid or the carrier matrix F such that the angle-dependent transmission of the optical element for light of the wavelength or wavelength range absorbed by the particles P is changed, the light being incident at an angle into the substrate S via the light incidence surface such that the light impinges on the thin layer.

For allThe subsequent observations with regard to fig. 23 to 26 proceed for the sake of simplicity from the variant of the Janus particle according to fig. 20, although for particles P_AAnd particles P_BThe same device function relationship can be realized by the design scheme of (1).

In a second operating state B2 shown in fig. 24, the first structure P of particles P₁Respectively on and facing the longitudinal sides of the lamellae, and a second structure P₂Facing away from the longitudinal side. In contrast, in the first operating state B1 shown in fig. 23, the second structure P of the particles P₂Are located on and facing the longitudinal sides of the lamellae, respectively, and the first structure P₁Facing away from the longitudinal side. The angle-dependent transmission in the first operating state B1 is due to the second configuration P₂Greater than 60% and in the second operating state B2 due to the first configuration P₁Less than 5%, respectively measured in an angular range greater than 30 ° with respect to the surface normal of the second large face of the substrate S and in a direction perpendicular to the longitudinal extension direction of the lamellae.

The optical element is provided with suitable electrodes E on its upper and lower sides (the upper and lower sides corresponding to the large faces)₁、E₂、E₃、E₄… (only a portion of which is shown and labeled) as an electromagnetic switching mechanism. Planar electromagnetic switching means formed on one or more sides of the cavities in the substrate are arranged, for example, on the narrow sides of the individual cavities. As can be seen by comparing fig. 23 and 24, the electrodes are switched on or polarized differently in different operating states in order to be able to effect a movement (rotation) of the Janus particles. The electromagnetic switching mechanism can be divided into a plurality of individually switchable segments, like the chamber, so that a local switchable property can be achieved between the first operating state and the second operating state B2. The embodiments described in connection with fig. 16 and 17 are equally applicable here, which also relates to the arrangement of the lamellae and the inclination of the cavities. The electrode E, E₁、E₂… may be arranged parallel, perpendicular or at other defined angles to the first major face of the substrate S.

It is also possible for the above-described embodiments to be designed such that the particles P are charged and the electromagnetic switching mechanism is designed as an electrode for generating a static or dynamic electric field, or the particles P are magnetic and the electromagnetic switching mechanism is designed as an electromagnetic layer for generating a static or dynamic magnetic field, so that the electromagnetic particles P in the electromagnetic field or magnetic field move in the fluid. For example, when a uniform electric field is applied, the corresponding electric field lines are formed in parallel at the center of the fluid chamber and show a larger deviation of parallelism at the edges.

Fig. 25 and 26 each show a schematic representation of a second embodiment of an optical element according to the third or fourth alternative in a sectional view, to be precise in fig. 25 the optical element in the operating state B1 and fig. 26 the optical element in the operating state B2. In a first operating state B1 according to fig. 25, the first structure P of the particles P is present₁Respectively located on and facing the narrow side of the thin layer, and a second structure P₂Away from the narrow side. In the second operating state B2 according to fig. 26, the second structure P of the particles P₂Respectively on and facing the narrow side of the thin layer, while the first structure P₂Away from the narrow side. The angle-dependent transmission, measured in the angular range of more than 30 ° with respect to the surface normal of the second large side of the substrate and in the direction perpendicular to the longitudinal extension direction of the lamellae, is greater than 60% in the first operating state B1 and less than 5% in the second operating state B2. Here, the electrode E also exists as an electromagnetic switching mechanism. The function of the optical element has already been described in connection with fig. 10.

At least two operating states are defined by means of the electromagnetic switching mechanism and the control circuit, wherein the angular transmission is greater than 50% in the first operating state B1 and less than 50% in the second operating state B2. This applies to the angular range of preferably +/-30 ° to +/-90 ° measured with respect to the face normal of the second large face of the substrate and in a direction perpendicular to the longitudinal extension of the lamellar (fluid) cavity (i.e. in each case from-90 ° to-30 ° and at the same time from +30 ° to +90 °, but not between-30 ° and +30 °). The angular range may also vary and include ranges of +/-10 deg. to +/-90 deg., +/-20 deg. to +/-90 deg., +/-45 deg. to +/-90 deg., or +/-25 deg. to +/-90 deg., respectively, instead of +/-30 deg.. The longitudinal extension direction is defined here by a straight line connecting the surface center points of the two outer sides of each fluid chamber.

Particles P capable of being moved electrophoretically or magnetophoretically_AOr Janus particle structure P₁The wavelength or wavelengths or wavelength ranges of the absorbed light preferably lie in the visible spectrum and particularly preferably completely cover the visible spectrum. However, the wavelength or wavelength range may also be outside the visible spectrum for special purposes, for example for the purpose of measurement techniques, for example when it is desired to influence UV light or IR light. The general embodiments already made above are equally applicable here, in particular with regard to the nature and geometry of the substrate and the position of the light entry and exit faces.

Advantageously, the particles P comprise first particles P_AAnd/or second particles P_BThe first and/or second particles are embedded in a stationary capsule body which is located on the edge surface of the cavity R or forms the cavity R, or in which the particle P is constructed as a Janus particle which is fixedly located on the edge surface of the cavity R but can rotate freely. When the particles P include the first particles P_AAnd/or second particles P_BWhile the first particles P_AAnd second particles P_BCan move in translation along an electric or magnetic field. Alternatively, if the particle (P) is designed as a Janus particle, the movement is preferably a rotational movement around a predetermined axis parallel to the longitudinal or narrow side of the thin layer.

A cavity of lamellar configuration with longitudinal sides and narrow sides extending between a first large face and a second large face can, for example, be oriented parallel to the large faces and in the simplest case has the shape of a cuboid. However, it may also be trapezoidal or curved (e.g. arched) narrow sides. In the case of a (non-cuboidal) cuboid shape, the narrow side is then an elongate side having a smaller area than the longitudinal side, which in turn usually has the largest area of all six surfaces of the fluid chamber. In general, the narrow sides are arranged parallel or (in addition to the oblique angles described further below) parallel to the large faces of the substrate, while the longitudinal sides are arranged perpendicular or (in addition to the oblique angles) perpendicular to the large faces of the substrate. In contrast, the remaining outer side surfaces are two surfaces, which are not embodied as narrow side and longitudinal side. It is also clear that the cavities protrude at least partially on one or both large faces of the substrate. Exemplarily, the fluid chambers formed in lamellae are between 2 μm and 30 μm wide (distance of longitudinal sides of the fluid chambers from a longitudinal side) in a first plane parallel to the main extension direction of the substrate and are spaced from each other by a minimum of 10 μm and a maximum of 150 μm (distance from immediately adjacent longitudinal sides of immediately adjacent fluid chambers), respectively. Finally, the cavity R, which is shown as lamellar, may have a height (narrow side to narrow side distance) of at least 10 μm and at most 300 μm, measured in a plane perpendicular to the first plane.

Advantageously, these cavities are filled with a scaffold matrix F, which is configured as a polymer matrix and in particular as a gel matrix. This polymer matrix has a characteristic mesh size. By this mesh size, the smaller particles P have less "drag" when moving than the larger particles P, and thus the smaller particles P and the larger particles P move at different speeds, respectively. On the one hand, if these particles are designed as first particles P of a first type_AAnd second particles P of a second type_BThis is advantageous for controlling the response time and for accelerating the uniform distribution of the particles P; however, this is not relevant for the capsule body and the Janus particles. On the other hand, such a polymer matrix has the advantage that diffusion is strongly prevented and the particles P therefore do not move spontaneously, which is advantageous for capsule bodies. If the cavity is filled with a fluid, a refractive index contrast with respect to the fluid F is necessary in the case of scattering particles P.

For the particles P including the first particles P_AAnd/or second particles P_BIn the case of the first particles P_AFor example nanoparticles, quantum dots and/or colorants which are designed to have a spatial extent of at most 200nm, preferably at most 50nm, particularly preferably at most 20 nm. Second particles P_BFormed as transparent or reflective spheres having a diameter between 5nm and 5000 nm. Here, the first and second liquid crystal display panels are, for example,it is conceivable that the first particles P_AFormed as BPQD (Black phosphorus Quantum dot), lead sulfide (P)_BS), CdSeII type quantum dots, azo colorants and/or metal oxide particles, preferably CrO (in particular chromium (IV) oxide) or Fe₂O₃And has a size between 2nm and 50nm, inclusive.

In a further variant, the particle P is designed as a Janus particle with a spherical surface, wherein the first and second regions are each formed by a hemisphere of the spherical surface. The particles P are designed as microparticles and have a spatial extent of at most 200 μm, preferably at most 50 μm, particularly preferably at most 20 μm. It is particularly contemplated that the Janus particles are formed of a transparent material, preferably polystyrene, melamine resin or silicon dioxide, and one hemisphere thereof is covered with a metal layer or a metal nanoparticle layer to achieve electrophoretic properties.

Furthermore, it is also possible to form the Janus particles from a transparent material, preferably polystyrene, melamine resin or silicon dioxide, and to achieve magnetophoretic properties one of the hemispheres is covered by a ferromagnetic and absorptive metal layer or metal oxide layer or ferromagnetic nanoparticle layer, preferably by Fe₂O₃The nanoparticles are covered and the other hemisphere is covered by a reflective layer, preferably a silver or aluminum layer, or a white layer.

As described above, the fundamental feature of spherical Janus particles is to have two hemispheres different from each other in physical properties. The first hemisphere scatters or reflects light incident thereon and absorbs another incident light. Therefore, the first hemispheres absorbing the light almost satisfy the first particles P of the first type_AAnd the hemisphere of scattered/reflected light satisfies the second particle P of the second type_BThe characteristic of (c).

For example, a Janus particle suitable for use in an optical element may be designed to: a) transparent spheres (polystyrene, melamine resin or silica) or scattering spheres with absorbing hemispheres; b) a colored or black sphere with reflective hemispheres; and c) spheres having one reflective hemisphere each and one absorptive hemisphere each. The scattering spheres can be, for example, polymerizedTiO nanoparticles in styrene spheres or silica nanoparticles in polystyrene spheres. In general, all suitable materials having a white scattering or reflecting property can be considered. The refractive index contrast of the nanoparticles used with respect to the spherical material of the particles makes the transparent spheres more scattering. Alternatively, colored or black spheres for the particles P are also feasible, for example by polystyrene filled with absorbing nanoparticles, QDs or colorants. Such examples and particles P_AThe same applies to the examples of (1). Chromium (IV) oxide spheres with ferromagnetic properties may also be used. The reflective hemisphere can be converted, for example, by means of a film or nanoparticles of aluminum, chromium, silver or another metal, for example for the second particles P of the second type_BAs described. For absorptive hemispheres, e.g. carbon, chromium (IV) oxide, Fe₂O₃Can be used as a film or as for P_BPlanar nanoparticles are described.

The electrophoretic properties are determined by the properties of the surface. This can be improved or controlled by surface functionalization (preferably by higher zeta potentials), as already explained above in connection with the particle design. In order for the Janus particles to be magnetophoretic, either the sphere itself, i.e. the material of the sphere, has to be magnetophoretic or the surface coating of one of the hemispheres, i.e. more precisely in that hemisphere, has to be magnetophoretic. The magnetic material is, for example, nickel, iron or chromium (IV) oxide. In the selection of the material, care must be taken that the magnetic dipole of the sphere is permanent so that the Janus particles can be rotated in a targeted manner. This can be achieved, for example, by ferromagnetic Janus particles. Typically, the Janus particles are larger than 200nm in diameter and the thickness of the applied layer is larger than 10nm, but these values can also be more or less than 10 nm.

By the above-described embodiments of the optical element, the transmission can be influenced in dependence on the angle (and optionally perpendicularly), wherein the optical element can be switched between at least two operating states. It can be implemented inexpensively and can be used in particular widely for various types of screens in order to be able to switch between a view protection mode and a free-viewing mode, wherein the resolution of such screens is not substantially reduced.

The above-described optical element may be advantageously applied anywhere secret data is displayed and/or entered in combination with an image reproduction apparatus, for example when a PIN is entered or for data display at an automatic teller machine or at a payment terminal or for password entry on a mobile device or reading an e-mail. As mentioned above, the optical element can also be used in a passenger car. Furthermore, the optical element may be used in conjunction with an image rendering device for advertising purposes, for example if only advertisements having a particular size need to be viewed, while allowing other advertisements to be visible to all.