阅读说明：本技术 菲涅尔透镜、菲涅尔透镜组件及虚拟现实显示装置 (Fresnel lens, Fresnel lens assembly and virtual reality display device ) 是由 黄海涛 董瑞君 白家荣 韩娜 武玉龙 栗可 王晨如 马占山 陈丽莉 张�浩 崔钊 于 2021-09-09 设计创作，主要内容包括：本公开提供一种菲涅尔透镜、菲涅尔透镜组件及虚拟现实显示装置,属于显示技术领域,其可解决现有的菲涅尔透镜中容易形成杂散光,对正常光线造成干扰,降低显示效果的问题。本公开的菲涅尔透镜的至少一面具有多个锯齿状结构,锯齿状结构包括：入光面、出光面和侧面；入光面呈弧面型；出光面与入光面至少部分相对设置；侧面连接入光面和出光面；菲涅尔透镜还包括：杂散光消除结构；杂散光消除结构被配置为将经过锯齿状结构的侧面的光线进行遮挡或吸收。(The utility model provides a fresnel lens, fresnel lens subassembly and virtual reality display device belongs to and shows technical field, and it can solve and form stray light easily among the current fresnel lens, causes the interference to normal light, reduces display effect's problem. At least one side of the fresnel lens of the present disclosure has a plurality of sawtooth-shaped structures, and the sawtooth-shaped structures include: a light incident surface, a light emitting surface and a side surface; the incident light surface is in a cambered surface shape; the light emergent surface and the light incident surface are at least partially arranged oppositely; the side surface is connected with the light incident surface and the light emergent surface; the fresnel lens further includes: a stray light eliminating structure; the stray light eliminating structure is configured to block or absorb light passing through the side face of the sawtooth-shaped structure.)

1. A fresnel lens, wherein at least one side of the fresnel lens has a plurality of sawtooth-shaped structures, the sawtooth-shaped structures comprising: a light incident surface, a light emitting surface and a side surface; the incident light surface is of a cambered surface type; the light emergent surface and the light incident surface are at least partially arranged oppositely; the side face is connected with the light incident face and the light emergent face; the fresnel lens further includes: a stray light eliminating structure;

the stray light elimination structure is configured to shield or absorb light passing through the side face of the sawtooth-shaped structure.

2. The fresnel lens according to claim 1, wherein the stray light cancelling structure covers the side of a sawtooth-like structure.

3. Fresnel lens according to claim 2, characterised in that the flanks of the sawtooth-shaped structures have one or more grooves;

the stray light eliminating structure is filled in the one or more grooves.

4. The Fresnel lens according to claim 3, wherein the depth of the groove is less than or equal to H; h ═ L × tan α; wherein L is the height of the saw-toothed structure, and α is an included angle between the side surface and a normal surface of the saw-toothed structure.

5. The Fresnel lens according to claim 3, wherein the grooves have a cross-sectional shape in a direction perpendicular to the side surfaces of a triangle, a square, a trapezoid or a semicircle.

6. The fresnel lens according to claim 1, wherein the stray light elimination structure comprises: and a black matrix.

7. A Fresnel lens assembly comprising a plurality of Fresnel lenses according to any one of claims 1 to 6;

centers of the Fresnel lenses are positioned on the same straight line.

8. The fresnel lens assembly of claim 7, wherein an air gap is provided between some adjacent ones of the plurality of fresnel lenses.

9. The fresnel lens assembly of claim 7, wherein the focal length of the fresnel lens assembly is between 10 mm and 25 mm.

10. A virtual reality display apparatus, wherein the virtual reality display apparatus comprises a fresnel lens assembly according to any one of claims 7 to 9.

Technical Field

The utility model belongs to the technical field of show, concretely relates to fresnel lens, fresnel lens subassembly and virtual reality display device.

Background

In the Virtual Reality (VR) display technology, a display image displayed on a display panel is generally imaged to a position 25 mm to 50 mm in front of human eyes or closer by using a lens, and different images are respectively seen by left and right eyes of a person, so that a stereoscopic impression is generated after brain processing, and a user has an immersive feeling.

The prior virtual reality display device can adopt a straight-through type aspheric lens component and a return type aspheric lens component to realize the convergence of light rays, wherein the straight-through type aspheric lens component has high luminous efficiency which can reach more than 80 percent, but has thicker thickness which is generally more than 35 mm; the thickness of the folding lens component is thin and can reach below 25 mm, but the light efficiency is low and is generally less than 25%. In order to achieve the effects of high light efficiency and thin thickness, a fresnel lens assembly is often adopted, however, in the fresnel lens, an invalid surface exists, and light rays easily generate stray light after passing through the invalid surface, so that the display effect is affected, and the use experience of a user is reduced.

Disclosure of Invention

The present disclosure is directed to at least one of the technical problems in the prior art, and provides a fresnel lens, a fresnel lens assembly and a virtual reality display apparatus.

In a first aspect, an embodiment of the present disclosure provides a fresnel lens, where at least one surface of the fresnel lens has a plurality of sawtooth structures, where the sawtooth structures include: a light incident surface, a light emitting surface and a side surface; the incident light surface is of a cambered surface type; the light emergent surface and the light incident surface are at least partially arranged oppositely; the side face is connected with the light incident face and the light emergent face; the fresnel lens further includes: a stray light eliminating structure;

the stray light elimination structure is configured to shield or absorb light passing through the side face of the sawtooth-shaped structure.

Optionally, the stray light eliminating structure covers the side face of the sawtooth-shaped structure.

Optionally, the side of the sawtooth-like structure has one or more grooves;

the stray light eliminating structure is filled in the one or more grooves.

Optionally, the depth of the groove is less than or equal to H; h ═ L × tan α; wherein L is the height of the saw-toothed structure, and α is an included angle between the side surface and a normal surface of the saw-toothed structure.

Optionally, the cross-sectional shape of the groove in a direction perpendicular to the side surface is triangular, square, trapezoidal, or semicircular.

Optionally, the stray light eliminating structure includes: and a black matrix.

In a second aspect, embodiments of the present disclosure provide a fresnel lens assembly comprising a plurality of fresnel lenses as provided above;

centers of the Fresnel lenses are positioned on the same straight line.

Optionally, an air gap is provided between some adjacent fresnel lenses in the plurality of fresnel lenses.

Optionally, the focal length of the fresnel lens assembly is 10 mm to 25 mm.

In a third aspect, embodiments of the present disclosure provide a virtual reality display apparatus, which includes the fresnel lens assembly provided as described above.

Drawings

FIG. 1 is a schematic diagram of an exemplary Fresnel lens configuration;

FIG. 2 is a schematic cross-sectional view of the Fresnel lens shown in FIG. 1 along the direction A-A';

FIG. 3 is a light path diagram of the Fresnel lens shown in FIG. 2;

fig. 4 is a schematic structural diagram of a fresnel lens provided in an embodiment of the present disclosure;

fig. 5 is a schematic structural diagram of another fresnel lens provided in the embodiment of the present disclosure;

fig. 6 is a schematic structural diagram of another fresnel lens provided in the embodiment of the present disclosure;

FIG. 7 is a schematic diagram of a sawtooth-shaped structure in a Fresnel lens provided by an embodiment of the present disclosure;

fig. 8 is a schematic structural diagram of a fresnel lens assembly provided in an embodiment of the present disclosure;

FIG. 9 is a graph of a modulation transfer function of the Fresnel lens assembly shown in FIG. 8;

FIG. 10 is a schematic diagram of another Fresnel lens assembly provided by the embodiments of the present disclosure;

fig. 11 is a graph of a modulation transfer function of the fresnel lens assembly shown in fig. 10.

Detailed Description

For a better understanding of the technical aspects of the present disclosure, reference is made to the following detailed description taken in conjunction with the accompanying drawings.

Unless otherwise defined, technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this disclosure belongs. The use of "first," "second," and similar terms in this disclosure is not intended to indicate any order, quantity, or importance, but rather is used to distinguish one element from another. Also, the use of the terms "a," "an," or "the" and similar referents do not denote a limitation of quantity, but rather denote the presence of at least one. The word "comprising" or "comprises", and the like, means that the element or item listed before the word covers the element or item listed after the word and its equivalents, but does not exclude other elements or items. The terms "connected" or "coupled" and the like are not restricted to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "upper", "lower", "left", "right", and the like are used merely to indicate relative positional relationships, and when the absolute position of the object being described is changed, the relative positional relationships may also be changed accordingly.

Fig. 1 is a schematic structural diagram of an exemplary fresnel lens, and as shown in fig. 1, the fresnel lens is formed by removing excess optical material in a common lens by using an etching process based on the common lens, only preserving curvature of a part of a surface thereof, and forming a plurality of concentric rings from small to large by etching, wherein the plurality of concentric rings can form the fresnel lens, and the total weight and thickness of the lens can be reduced. Fig. 2 is a schematic cross-sectional structure view of the fresnel lens shown in fig. 1 along a direction a-a', and as shown in fig. 2, at least one surface of the fresnel lens has a plurality of sawtooth structures 101, and in the embodiment of the present disclosure, one surface of the fresnel lens has a plurality of sawtooth structures 101, and the other surface of the fresnel lens may be a spherical surface or an aspheric surface. The zigzag structure includes: light incident surface 1011, light emitting surface 1012, and side surface 1013; the light incident surface 1011 is arc-shaped; the light emitting surface 1012 and the light incident surface 1011 are at least partially disposed opposite to each other; the side surface 1013 connects the light incident surface 1011 and the light emitting surface 1012. In practical applications, the width of each sawtooth-shaped structure 101 may be equal to form an equally spaced fresnel lens structure, or the height of each sawtooth-shaped structure 101 may be equal to form an equally toothed fresnel lens structure. The size of the sawtooth-shaped structure 101 in the fresnel lens can be set reasonably according to actual needs, and is not limited herein.

Fig. 3 is an optical path diagram of the fresnel lens shown in fig. 2, and as shown in fig. 3, when light enters from the light incident surface 1011, the light can be refracted once inside the saw-tooth structure 101 after passing through the light incident surface 1011, and then exits from the light exiting surface 1012, so as to achieve the light converging effect. When a light ray enters from the edge of the light incident surface 1011, the light ray passing through the light incident surface 1011 can be refracted once inside the saw-tooth structure 101, and at this time, the light ray can exit from the side surface 1013, enter the light incident surface 1011 of the adjacent saw-tooth structure 101 again, and be refracted once again, and finally exit from the light exit surface 1012 of the adjacent saw-tooth structure 101.

It can be seen that most of the light rays incident on the light incident surface 1011 are refracted only once inside the sawtooth-shaped structure 101, but the light rays incident on the edge of the light incident surface 1011 are refracted twice inside the sawtooth-shaped structure 101. In practical applications, the light incident surface 1011 of the sawtooth-shaped structure 101 may be defined as an effective surface, and the side surface 1013 of the sawtooth-shaped structure 101 may be defined as an ineffective surface, because the light incident from the effective surface and the ineffective surface has different refraction times in the sawtooth-shaped structure 101 and different light paths, the light passing through the ineffective surface of the sawtooth-shaped structure 101 is likely to form stray light, which affects the display effect, thereby reducing the user experience.

In order to solve at least one of the above technical problems, embodiments of the present disclosure provide a fresnel lens, a fresnel lens assembly, and a virtual reality display apparatus, and the fresnel lens, the fresnel lens assembly, and the virtual reality display apparatus provided in embodiments of the present disclosure will be described in further detail with reference to the accompanying drawings and specific embodiments.

Fig. 4 is a schematic structural diagram of a fresnel lens provided in an embodiment of the present disclosure, and as shown in fig. 4, at least one surface of the fresnel lens has a plurality of sawtooth structures 101, in the embodiment of the present disclosure, a surface of the fresnel lens has a plurality of sawtooth structures 101 as an example, and another surface of the fresnel lens may be a spherical surface or an aspheric surface. The serration structure 101 includes: light incident surface 1011, light emitting surface 1012, and side surface 1013; the light incident surface 1011 is arc-shaped; the light emitting surface 1012 and the light incident surface 1011 are at least partially disposed opposite to each other; the side surface 1013 connects the light incident surface 1011 and the light emitting surface 1012; the fresnel lens further includes: a stray light eliminating structure 102; the stray light eliminating structure 102 is configured to block or absorb light passing through the side surface 1013 of the sawtooth-shaped structure 101.

For example, the serrated structure 101 may be made of a material with high transparency, such as glass and acrylic, so that light can be effectively transmitted in the serrated structure 101 in a polar manner, blocking of the serrated structure 101 to light is reduced, and the light efficiency of the fresnel lens is improved. The stray light elimination structure 102 may be made of black or other dark light-shielding materials to effectively shield or absorb light, so as to prevent stray light from being formed, and further prevent the stray light from interfering with normal light.

In the fresnel lens provided in the embodiment of the present disclosure, after most of the light rays are incident through the light incident surface 1011, most of the light rays can be refracted once inside the saw-toothed structure 101, so as to achieve the light ray convergence effect; when a small portion of light is incident through the edge of the light incident surface 1011, the small portion of light can be refracted once inside the sawtooth-shaped structure 101, and the light after being refracted once irradiates the side surface 1013 of the sawtooth-shaped structure 101, the stray light elimination structure 102 can block or absorb the small portion of light, so that the small portion of light is prevented from entering the light incident surface 1011 of the adjacent sawtooth-shaped structure 101 through the side surface 1013 of the sawtooth-shaped structure 101 again and being refracted twice, that is, the light passing through the invalid surface is blocked or absorbed, thus preventing the stray light from entering the field of view of the user at the light emitting surface 1012 of the sawtooth-shaped structure 101, and therefore the interference of the stray light on the normal light can be avoided, the display effect can be improved, and the use experience of the user can be improved.

It can be understood that the fresnel lens provided in the embodiment of the present disclosure may also have a plurality of sawtooth structures 101 on both sides, and a plurality of corresponding stray light elimination structures 102 are provided, and the implementation principle of the fresnel lens is the same as that of the fresnel lens described above, and therefore, no further description is provided here. In practical applications, the type of the fresnel lens can be reasonably selected according to practical needs, and is not limited herein. The dimensions such as the arc of the light incident surface 1011 and the angle with the side surface 1013 of the sawtooth structure 101 may be set as needed, and are not limited here.

In some embodiments, as shown in fig. 4, the stray light elimination structure 102 covers the side 1013 of the sawtooth-shaped structure 101.

In the embodiment of the present disclosure, the stray light eliminating structure 102 may cover the side 1013 of the zigzag structure 101, and the stray light eliminating structure 102 may shield or absorb the light passing through the side 1013 of the zigzag structure 101, so that the light may be prevented from being transmitted inside the zigzag structure 101 and refracted for multiple times to form stray light, thereby avoiding interference of the stray light on normal light, improving the display effect, and further improving the user experience.

In some embodiments, fig. 5 is a schematic structural diagram of another fresnel lens provided in the embodiments of the present disclosure, and fig. 6 is a schematic structural diagram of another fresnel lens provided in the embodiments of the present disclosure, as shown in fig. 5, a side surface 1013 of the sawtooth-shaped structure 101 has one groove 1014, as shown in fig. 6, a side surface of the sawtooth-shaped structure 101 has a plurality of grooves 1014; the stray light elimination structure 102 is filled in the one or more grooves 1014.

For example, the side 1013 of the sawtooth-shaped structure 101 may be etched by using a photolithography process, and one or more grooves 1014 are formed on the side 1013 of the sawtooth-shaped structure 101, where the one or more grooves 1014 can provide a coating or deposition position for the stray light eliminating structure 102, so as to ensure that the stray light eliminating structure 102 can be stably coated or deposited on the side 1013 of the sawtooth-shaped structure 101 during the manufacturing process, so that the stray light eliminating structure 102 can block or absorb a part of light incident from the edge of the light incident surface 1011 of the sawtooth-shaped structure 101, and prevent the part of light from entering the light incident surface 1011 of the adjacent sawtooth-shaped structure 101 through the side 1013 of the sawtooth-shaped structure 101 to cause secondary refraction, i.e. blocking or absorbing the light passing through the inactive surface, 1012 can prevent the formation of stray light on the light emitting surface of the sawtooth-shaped structure 101 and enter the user's field of view, therefore, the interference of stray light to normal light can be avoided, the display effect can be improved, and the use experience of a user can be improved.

In some embodiments, the depth of the recess 1014 is less than or equal to H; h ═ L × tan α; wherein, L is the height of the saw-toothed structure, and alpha is the included angle between the side surface and the normal surface of the saw-toothed structure.

Fig. 7 is a schematic diagram of a sawtooth-shaped structure in a fresnel lens provided by an embodiment of the disclosure, as shown in fig. 7, in an ideal state, a side surface 1013 of the sawtooth-shaped structure 101 needs to be perpendicular to a horizontal plane, that is, the side surface 1013 of the sawtooth-shaped structure 101 needs to be parallel to a normal plane, however, because a drawing process needs to be performed in a preparation process, an included angle α, that is, a drawing angle, of about 15 degrees is generally formed between the side surface 1013 of the sawtooth-shaped structure 101 and the normal plane due to a process error, a redundant structure is formed at a position of the side surface 1013 of the sawtooth-shaped structure 101, and when one or more grooves 1014 are formed, a depth of the groove 1014 needs to refer to a thickness of the redundant structure. The thickness H of the redundant structure, the height L of the sawtooth-shaped structure 101, and the draft angle α satisfy the following relationship: h ═ L tan α, the depth of the recess 1014 needs to be less than or equal to the thickness H of the redundant structure. For example, the depth of the groove 1014 may be smaller near the light incident surface 1011 and larger near the light exiting surface 1012. The depth of the recess 1014 generally does not exceed the thickness of the redundant structure, which avoids the recess being too deep and affecting the optical performance of the sawtooth-like structure 101.

In some embodiments, the cross-sectional shape of the recess 1014 in a direction perpendicular to the sides 1013 is triangular, square, trapezoidal, or semi-circular.

The cross-sectional shape of the groove 1014 in the direction perpendicular to the side surface 1013 may be a triangle, a square, a trapezoid, or a semicircle, and in the embodiment of the present disclosure, the cross-sectional shape is a semicircle is taken as an example for illustration, a light-shielding material may be deposited or coated in the formed semicircle groove 1014 to form a stray light eliminating structure, and the semicircle groove 1014 may provide a deposition or coating position for the light-shielding material, so as to ensure that, during the manufacturing process, the stray light eliminating structure 102 may be stably coated or deposited on the side surface 1013 of the sawtooth-shaped structure 101, so that the stray light eliminating structure 102 may shield or absorb a portion of the light incident from the edge of the light incident surface 1011 of the sawtooth-shaped structure 101, and prevent the portion of the light from entering the light incident surface 1011 of the adjacent sawtooth-shaped structure 101 through the side surface 1013 of the sawtooth-shaped structure 101 again to cause secondary refraction, that is, i.e. shield or absorb the light passing through the inactive surface, therefore, stray light formed on the light emitting surface 1012 of the sawtooth-shaped structure 101 can be prevented from entering the field of view of a user, so that the interference of the stray light on normal light can be avoided, the display effect can be improved, and the use experience of the user can be improved. It is understood that the recess 1014 may be formed in other shapes as long as it provides a deposition or coating location for the light blocking material, which is not illustrated.

In some embodiments, the stray light elimination structure 102 includes: and a black matrix.

The stray light elimination structure 102 may be formed by using a black matrix commonly used in the display field, so that it is not necessary to develop a new material for shielding or absorbing light, thereby reducing the manufacturing cost.

The embodiment of the present disclosure further provides a fresnel lens assembly, which includes a plurality of non-fresnel lenses provided in any of the above embodiments; the centers of the Fresnel lenses are located on the same straight line.

The light converging effect of the fresnel lens provided by the embodiment of the present disclosure will be further described in detail with reference to specific examples.

Example one: fig. 8 is a schematic structural diagram of a fresnel lens assembly provided in an embodiment of the present disclosure, and as shown in fig. 8, three fresnel lenses are provided in the fresnel lens assembly, and a plurality of sawtooth structures are provided on both sides of each fresnel lens. Fig. 9 is a graph of the modulation transfer function of the fresnel lens assembly shown in fig. 8. as shown in fig. 8 and 9, the three-piece fresnel lens assembly can achieve the effects of a focal length of 21 mm, an overall length of the assembly of 20 mm, a field angle of 90 °, and an Eye box of 8 mm by 8 mm.

Example two: fig. 10 is a schematic structural diagram of another fresnel lens assembly provided in the embodiment of the present disclosure, and as shown in fig. 10, five fresnel lenses are provided in the fresnel lens assembly, and a plurality of sawtooth structures are provided on both sides of each fresnel lens. Fig. 11 is a graph of the modulation transfer function of the fresnel lens assembly shown in fig. 10. as shown in fig. 10 and 11, the three-piece fresnel lens assembly can achieve the effects of a focal length of 16.9 mm, an overall length of the assembly of 20 mm, a field angle of 65 °, and an Eye box of 9 mm × 9 mm.

As can be seen from the two examples described above, the fresnel lens assembly provided by the embodiments of the present disclosure can effectively reduce the thickness of the lens assembly (the thickness is less than or equal to 20 mm), and can achieve a higher luminous efficacy (the luminous efficacy is greater than or equal to 80%). In addition, according to the fresnel lens assembly provided by the embodiment of the disclosure, after most of the light rays are incident through the light incident surface, most of the light rays can be refracted once inside the sawtooth-shaped structure, so that the light ray convergence effect is realized; after a small part of light is incident through the edge position of the light incident surface, the small part of light can be refracted once inside the sawtooth-shaped structure, when the light which is refracted once irradiates the side surface of the sawtooth-shaped structure, the stray light eliminating structure can shield or absorb the small part of light, the situation that the small part of light enters the light incident surface of the adjacent sawtooth-shaped structure through the side surface of the sawtooth-shaped structure again to cause secondary refraction is avoided, namely, the light which passes through the invalid surface is shielded or absorbed, so that the situation that stray light enters the visual field of a user from the light emergent surface of the sawtooth-shaped structure can be prevented, the interference of the stray light on normal light can be avoided, the display effect can be improved, and the use experience of the user can be improved.

In some embodiments, as shown in fig. 8 and 10, an air gap is provided between some adjacent fresnel lenses in the plurality of fresnel lenses.

Some air gaps are arranged between the adjacent Fresnel lenses, the specific width of the air gaps can be adjusted, the focal length and the thickness of the Fresnel lens assembly are adjusted, clear display images are formed in the visual field of a user, the display effect is improved, and the use experience of the user is improved.

In some embodiments, the focal length of the fresnel lens assembly is 10 mm to 25 mm.

In the embodiment of the present disclosure, the focal length of the fresnel lens assembly may be 10 mm to 25 mm, and a smaller focal length may be obtained by setting the number of fresnel lenses in the fresnel lens assembly and the air gap between some adjacent fresnel lenses according to actual needs, so as to implement near-eye display.

The embodiment of the present disclosure further provides a virtual reality display apparatus, where the virtual reality display apparatus includes the fresnel lens assembly provided in any of the above embodiments, and the implementation principle and the technical effect of the virtual reality display apparatus are the same as those of the fresnel lens and the fresnel lens assembly, and are not described herein again. It can be understood that the fresnel lens assembly provided in the embodiments of the present disclosure may be applied to a virtual reality display device, and may also be applied to an augmented reality display device, and other near-eye display devices such as a pair of dimming glasses, which are not listed here.

It is to be understood that the above embodiments are merely exemplary embodiments that are employed to illustrate the principles of the present disclosure, and that the present disclosure is not limited thereto. It will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the disclosure, and these are to be considered as the scope of the disclosure.