阅读说明：本技术 投影屏幕和投影系统 (Projection screen and projection system ) 是由 王霖 孙微 胡飞 于 2018-05-31 设计创作，主要内容包括：本发明的目的是提供一种投影屏幕,其包括从光入射侧依次设置的基板、全反射层和用于吸收光线的吸光层,其中,所述全反射层具有多个在所述投影屏幕的垂直方向上延伸的梯形微结构,所述多个梯形微结构在所述投影屏幕的水平方向上周期性排列。该投影屏幕具有结构简单、加工容易、成本低以及对比度高的特点。(The invention aims to provide a projection screen, which comprises a substrate, a total reflection layer and a light absorption layer for absorbing light, wherein the substrate, the total reflection layer and the light absorption layer are sequentially arranged from a light incidence side, the total reflection layer is provided with a plurality of trapezoidal microstructures extending in the vertical direction of the projection screen, and the plurality of trapezoidal microstructures are periodically arranged in the horizontal direction of the projection screen. The projection screen has the characteristics of simple structure, easiness in processing, low cost and high contrast.)

1. A projection screen comprises a substrate, a total reflection layer and a light absorption layer for absorbing light,

The total reflection layer is provided with a plurality of trapezoidal microstructures extending in the vertical direction of the projection screen, and the trapezoidal microstructures are periodically arranged in the horizontal direction of the projection screen.

2. The projection screen of claim 1, wherein each of the trapezoidal microstructures has a cross section in the shape of an isosceles trapezoid having a lower base side facing a light incident side and an upper base side facing the light absorbing layer, the lower base side being longer than the upper base side.

3. The projection screen of claim 1, further comprising a diffusion layer for diffusing light from the total reflection layer, wherein the diffusion layer and the total reflection layer are respectively formed on both sides of the substrate.

4. The projection screen of claim 1, further comprising a diffusion layer for diffusing light from the total reflection layer, wherein the diffusion layer and the total reflection layer are attached to both sides of the substrate, respectively.

5. The projection screen of claim 1, further comprising a diffusion layer for diffusing light from the total reflection layer, the substrates including a first substrate and a second substrate attached to each other, the total reflection layer being formed on the first substrate, the diffusion layer being formed on a face of the second substrate opposite to a face to which the first substrate is attached.

6. The projection screen of claim 3, wherein the diffuser layer is formed by hot embossing or UV glue transfer.

7. The projection screen of claim 3, wherein the substrate comprises a first substrate and a second substrate attached to each other, the total reflection layer is formed on the first substrate, and the diffusion layer is formed on a face of the second substrate opposite to a face to which the first substrate is attached.

8. The projection screen of claim 1, wherein the ratio of the length of the upper base side to the length of the lower base side of the trapezoidal microstructure of the total reflection layer is in the range of 0.05-0.9.

9. The projection screen of claim 1, wherein the substrate comprises PET, PC, PVC, or PMMA.

10. A projection system, comprising:

A projection screen, wherein the projection screen is according to any one of claims 1-9; and

A tele projector that emits projection light from the light incident side toward the projection screen.

Technical Field

The invention relates to a projection screen and a projection system comprising the same.

Background

In projection display systems, the screen is an important factor affecting its performance, especially with regard to the image quality of the projection display. For a screen, the contrast is an important parameter for evaluating the quality of the screen.

In the prior art, the contrast of the picture reflected by the screen is far lower than that of the projector due to the influence of the ambient light. This is because prior art projection screens reflect both projector light and ambient light.

To improve the contrast of the screen in the presence of ambient light, current projection screens that are resistant to ambient light typically employ wire grid screens that improve ambient light contrast by having one surface for light absorption and the other surface for reflected light. But the gain of such screens is low. Another approach for projection screens that are resistant to ambient light is typically achieved by using an array of microstructures to heat either the reflective layer or the light absorbing layer. However, in this structure, there are still some angles of ambient light reflected toward the viewer side, and thus the effect of improving the contrast is limited.

Disclosure of Invention

In order to solve the technical problems, the invention provides a projection screen for a long-focus projector, which has the characteristics of simple structure, easy processing, low cost and high contrast.

One embodiment of the present invention discloses a projection screen, which includes a substrate, a total reflection layer, and a light absorption layer for absorbing light, which are sequentially disposed from a light incident side, wherein the total reflection layer has a plurality of trapezoidal microstructures extending in a vertical direction of the projection screen, and the plurality of trapezoidal microstructures are periodically arranged in a horizontal direction of the projection screen.

The projection screen comprises a total reflection layer and a diffusion layer, and projection light from a long-focus projector returns to a viewer side in a crossed mode after being totally reflected by the total reflection layer, so that the horizontal viewing angle is enlarged. In addition, the diffusion layer can further diffuse the viewing angle.

The total reflection layer in the projection screen of the present invention further has a trapezoidal microstructure including two inclined surfaces and a horizontal surface contacting the black light absorption layer. Because the horizontal plane of the trapezoid microstructure is contacted with the black light absorption layer, the ambient light incident on the horizontal plane is absorbed by the black light absorption layer, and the ambient light incident on the inclined plane of the trapezoid microstructure is reflected to the horizontal plane and then absorbed by the black light absorption layer. Therefore, the projection screen can fully absorb the ambient light, thereby obtaining a high-contrast image.

It is to be understood that the advantageous effects of the present invention are not limited to the above-described effects, but may be any of the advantageous effects described herein.

drawings

Fig. 1 is a perspective view illustrating a projection system including a projector and a projection screen.

Fig. 2 is a schematic diagram illustrating a structure of a projection screen according to the present invention.

fig. 3 is a perspective view illustrating the structure of the substrate and the total reflection layer in the present invention.

Fig. 4 is a plan view illustrating a total reflection layer in the present invention.

Fig. 5 illustrates a variation of the construction of the projection screen of the present invention.

Fig. 6 illustrates another variation of the projection screen configuration of the present invention.

fig. 7 illustrates the path of the projected light from the projector in a trapezoidal microstructure.

Fig. 8 illustrates a cross-sectional view of a case where ambient light is incident on the projection screen shown in fig. 4.

fig. 9 illustrates a perspective view of a case where ambient light is incident on the projection screen shown in fig. 4.

Fig. 10a and 10b illustrate simulation results of reflected light distributions of ambient light under conditions of different aperture factors.

Fig. 11 illustrates simulation results of screen brightness variation under different aperture factors.

Fig. 12 illustrates a cross-sectional view of a first structure of a trapezoidal microstructure in a projection screen.

Fig. 13 illustrates a cross-sectional view of a second configuration of a trapezoidal microstructure in a projection screen.

fig. 14 illustrates an intensity curve of reflected light of projected light.

Detailed Description

Hereinafter, specific embodiments according to the present invention will be described in detail with reference to the accompanying drawings. It is emphasized that all dimensions in the figures are merely schematic and not necessarily to scale, thus not limiting. For example, it should be understood that the dimensions, ratios, etc. of the diffusion layer, the total reflection layer, the black light absorbing layer, etc. are not shown in the drawings according to actual dimensions and ratios, but are for convenience of illustration only, and are not intended to limit the specific scope of the present invention.

In the following, an exemplary structure of a projection screen according to the present invention is first described with reference to fig. 1 to 4, where fig. 1 illustrates a projection system including a projector and a projection screen, and as shown in fig. 1, a vertical direction of the projection screen is a picture up-down direction and a horizontal direction of the projection screen is a picture left-right direction with respect to a viewer in front of the screen. The "vertical direction of the screen" and the "horizontal direction of the screen" described in the other drawings of the present invention are the same.

Fig. 2 illustrates the structure of a projection screen according to the present invention. As shown in fig. 2, the projection screen is composed of a diffusion layer 40, a substrate 10, a total reflection layer 20, and a black light absorbing layer 30 in this order from a viewer side (i.e., a light incident side), wherein the diffusion layer 40 and the total reflection layer 20 are respectively formed on both sides of the substrate 10, and the black light absorbing layer 30 is formed to be in contact with the total reflection layer 20.

In the above structure, the diffusion layer 40 is used for diffusing the emergent light from the total reflection layer 20, and the black light absorbing layer 30 is used for absorbing the light incident on the black light absorbing layer 30, and the two structures can adopt related art structures in the prior art, and therefore, the description of the invention is omitted. The substrate 10 may include organic materials such as PET, PC, PVC, PMMA, etc. The total reflection layer 20 in the projection screen will be described in detail hereinafter.

Fig. 3 is a perspective view illustrating the structure of the substrate 10 and the total reflection layer 20 in the structure shown in fig. 2. Fig. 4 is a plan view illustrating the total reflection layer 20 in the structure shown in fig. 2. As shown in fig. 3 and 4, the total reflection layer 20 includes a plurality of trapezoidal microstructures extending in the up-down direction of the screen, each of the trapezoidal microstructures including two inclined planes having complementary angles and the same length in the inclined direction and two horizontal planes (i.e., an upper bottom plane and a lower bottom plane) which constitute a trapezoidal structure. Preferably, the trapezoid structure is an isosceles trapezoid structure, so that the reflected light is easier to control. A plurality of the trapezoidal microstructures are periodically arranged in the left-right direction of the screen, thereby forming an isosceles trapezoidal microstructure array serving as the total reflection layer 20.

In the present invention, the total reflection layer 20 may be processed to be formed by coating on the side of the substrate 10 opposite to the viewer side.

Since the isosceles trapezoid structure in the total reflection layer 20 is simply processed, the projection screen can be more easily manufactured.

As can be seen by referring to fig. 2 and 3, in the trapezoidal microstructure of the total reflection layer 20, a horizontal plane having a shorter length in the left-right direction of the screen is adjacent to the black light absorbing layer 30.

In the projection screen shown in fig. 2, the total reflection layer 20 and the diffusion layer 40 may be formed on both sides of the same transparent substrate 10, respectively, by a thermal imprinting or UV glue transfer method.

Although fig. 2 shows a structure in which the total reflection layer 20 and the diffusion layer 40 are formed on both sides of the substrate 10, in the projection screen of the present invention, both side surfaces of the substrate 10 may be directly formed as the total reflection layer 20 and the diffusion layer 40, respectively, that is, the substrate 10, the total reflection layer 20, and the diffusion layer 40 are integrated into one layer, instead of being formed by laminating three layers as shown in fig. 2.

Fig. 5 illustrates a variation of the construction of the projection screen of the present invention. Other relevant features and descriptions (e.g., the trapezoidal microstructure of the total reflection layer 20, etc.) in fig. 5 are the same as those of the projection screen in fig. 2 except for the following differences, and thus will not be described again.

Unlike the projection screen structure of fig. 2, the total reflection layer 20 and the diffusion layer 40 in fig. 5 are formed on two opposite sides of the two substrates 10, 11, respectively, i.e., the total reflection layer 20 is formed on the substrate 10, and the diffusion layer 40 is formed on the side of the substrate 11 opposite to the side facing the substrate 10. In the structure of fig. 5, the facing surfaces of the substrates 10 and 11 are bonded together.

Although fig. 5 describes that the total reflection layer 20 is formed on one side of the substrate 10 and the diffusion layer 40 is formed on the opposite side of the substrate 11 from the side facing the substrate 10, one side of the substrate 10 may be directly formed as the total reflection layer 20 and the other side of the substrate 11 may be formed as the diffusion layer 40.

That is, the total reflection layer 20 is integrated with the substrate 10 as one layer, and the diffusion layer 40 is integrated with the substrate 11 as one layer. The facing surfaces of the substrates 10 and 11 are then bonded together.

In this modification, the total reflection layer 20 and the diffusion layer 40 are formed on the two substrates 10 and 11, respectively, by a thermal imprint method or a UV glue transfer method.

Fig. 6 illustrates another variation of the projection screen configuration of the present invention. Other relevant features and descriptions (such as the trapezoidal microstructure of the total reflection layer 20, etc.) in fig. 7 are the same as those of the projection screen in fig. 2 except for the following differences, and thus will not be described again.

Unlike the projection screen structure of fig. 2, the diffusion layer 40 of fig. 2 is replaced with a bulk diffusion film 50 formed of a bulk diffusion material in fig. 6, and then the bulk diffusion film 50 is attached to the substrate 10 by glue, such as thermosetting glue. The bulk diffusion membrane 50 may be a bulk diffusion membrane that has been widely used commercially.

In addition, another layer structure, for example, a colored layer made of a dark color material, a scratch-resistant protective layer, an antireflection layer, or the like may be bonded to the bulk diffusion film 50 on the side opposite to the side to which the substrate 10 is bonded.

in addition, the projection screen of the present invention may also adopt a structure in which the diffusion layer 40 in fig. 5 is replaced with the bulk diffusion film 50 in fig. 6.

Hereinafter, the principle of the projection screen structure of the present invention capable of improving the ambient light contrast will be described with reference to fig. 8-9 by taking the projection screen structure shown in fig. 2 as an example.

Fig. 7 illustrates that the projection light P1 from the tele projector is incident on the screen in a direction approximately perpendicular to the screen plane, which is a plane composed of the screen up-down direction and the screen left-right direction.

The projection light P1 from the projector is totally reflected on the two inclined surfaces of the trapezoidal microstructure of the total reflection layer 20, respectively, and the outgoing light reflected by the two inclined surfaces returns to the viewer side in a mutually intersecting manner, thereby widening the horizontal viewing angle. In addition, the diffusion layer 40 can further diffuse the outgoing light, thereby enabling further expansion of the viewing angle.

It can be seen that, by the trapezoidal microstructure in the total reflection layer 20 of the present invention, the angle of the projection light from the projector can be diffused by the two inclined planes, so that the diffusion angle of the emergent light of the projection light in the horizontal direction is large, and the diffusion angle in the vertical direction is small. In addition, the diffusion layer 40 can further diffuse the angle of the outgoing light.

By using the total reflection layer 20 having the trapezoidal microstructure and the diffusion layer 40 in combination, the present invention can more effectively enlarge the viewing angle of the screen.

Fig. 8 illustrates a cross-sectional view of a case where ambient light is incident on the projection screen shown in fig. 2. Fig. 9 is a perspective view for explaining a case where ambient light is incident on the projection screen shown in fig. 2.

As shown in fig. 8 and 9, a portion of the ambient light a2 directly enters the horizontal plane of the trapezoidal microstructure of the total reflection layer 20, which is in contact with the black light absorbing layer 30, and is absorbed by the black light absorbing layer 30, another portion of the ambient light a1 does not directly enter the horizontal plane of the total reflection layer 20, which is in contact with the black light absorbing layer 30, but enters the inclined plane of the trapezoidal microstructure of the total reflection layer 20, and then enters the horizontal plane of the trapezoidal microstructure and the black light absorbing layer 30 after being totally reflected by the inclined plane, and is absorbed by the black light absorbing layer 30, and another portion of the projection light exits toward the bottom surface after being totally reflected by the inclined plane of the trapezoidal microstructure.

As can be seen from fig. 8 and 9, the ambient light ray a2 perpendicular to the screen plane is directly absorbed by the black light absorbing layer 30, and the ambient light ray a1 deviated from the normal of the screen plane is totally reflected by the inclined surface of the trapezoid microstructure

Is absorbed by the black light absorbing layer 30. Therefore, the high-angle ambient light ray a1 can be absorbed by the black light absorbing layer 30 as the ambient light ray a2, and another part of the ambient light is totally reflected by the inclined surface of the trapezoid microstructure and then exits toward the bottom surface.

Therefore, in the present invention, the absorption of the ambient light incident from multiple angles is considered, so that the trapezoidal microstructure is adopted in the total reflection layer 20, so that the black light absorption layer can absorb the ambient light incident from various angles, thereby improving the screen contrast more significantly.

As shown in the cross-sectional view in fig. 8, assuming that the length of the horizontal side adjacent to the black light absorbing layer 30 in the trapezoidal microstructure is set to d, and the Pitch of the microstructure is Pitch, that is, in the cross-sectional view, the length of the upper base side of the trapezoid in the trapezoidal microstructure is d, and the length of the lower base side is Pitch, the Aperture ratio (aperature) is defined as:

Opening factor d/pitch

Next, the results obtained by simulation of the reflected light distribution of the ambient light under the conditions of different aperture factors are explained with reference to fig. 10a and 10 b. In fig. 10a, the aperture factor is set to 0, i.e. the total reflection layer 20 has a triangular microstructure, and in fig. 10b, the aperture factor is set to greater than 0, i.e. the total reflection layer 20 has a trapezoidal microstructure.

As shown in fig. 10a, in the case that the total reflection layer 20 has a triangular microstructure, most of the ambient light is concentrated in a cashew shaped region under the vertical screen, which is a result of the ambient light being reflected toward the ground after being reflected multiple times by two inclined surfaces of the microstructure. However, in the case of this triangular microstructure, a portion of the ambient light is still present in the direction perpendicular to the plane of the screen, i.e. in the field of view facing the viewer. As shown in fig. 10b, the light in the vertical direction to the screen is significantly reduced after increasing the aperture factor.

fig. 11 shows simulation results of screen luminance variations under conditions of different aperture factors. As shown in fig. 11, when the aperture factor is less than 0.55, the screen gain is greater than 1 (screen gain of 1 is equivalent to lambertian brightness of 172Nits), and when the aperture factor exceeds 0.55, the screen gain drops below 1. Therefore, although the use of the total reflection layer 20 with the trapezoidal microstructure in the present invention may cause a portion of the projection light from the projector to be absorbed by the black light absorption layer 30, which may cause a decrease in screen gain, the present invention can significantly improve the ambient light resistance contrast of the projection screen by reasonably setting the aperture factor while ensuring the screen gain.

In the present invention, the numerical value of the opening factor may be set in the range of 0.05 to 0.9, preferably in the range of 0.1 to 0.5.

The following describes the schematic diagram of the optical path for total reflection in a projection screen with different trapezoidal microstructures with different structures with reference to fig. 12 and 13.

Fig. 12 illustrates a cross-sectional view of a first structure of a trapezoidal microstructure in a projection screen, in which an extension line angle θ of two inclined planes of the trapezoidal microstructure in the total reflection layer 20 is an acute angle. As in the description of the structure in fig. 2, since the projection light from the tele projector and incident perpendicularly to the screen plane is reflected on the two inclined surfaces of the total reflection layer 20, the reflected light is no longer parallel to the direction perpendicular to the screen plane. Thereby making the total reflection layer 20 having a trapezoidal microstructure have the effect of diffusing the projection light.

in fig. 12, the angle between the projected light and the inclined plane of the total reflection layer 20 is σ, the angle between the outgoing light reflected by the inclined plane and the normal direction perpendicular to the screen plane is α ₁ and α ₂, where α ₁ is α ₂, and the angle between the reflected light reflected by one inclined plane and the normal of the other inclined plane is ω, then it can be known from the geometrical relationship shown in fig. 12:

α₂＝180-2θ

Assuming that the refractive index of the material outside the inclined surface of the total reflection layer 20 is n ₁, and the refractive index of the material constituting the total reflection layer 20 is n ₂, the following relationship needs to be satisfied in order to satisfy the total reflection condition:

Therefore, the angle θ between the two inclined surfaces of the total reflection layer 20 is required to satisfy the following relationship:

the included angle alpha ₂ between the reflected light ray and the normal direction vertical to the plane of the screen satisfies the following conditions:

Therefore, an appropriate angle θ between the two inclined surfaces of the trapezoidal total reflection layer 20 can be confirmed from the refractive index n ₂ of the material constituting the total reflection layer 20 and the refractive index n ₁ of the material outside the inclined surfaces of the total reflection layer 20, and the diffusion angle obtained by the total reflection layer 20 can be calculated.

Fig. 13 illustrates a second structural cross-sectional view of the trapezoidal microstructure in the projection screen, in which an extended line angle θ of two inclined surfaces of the trapezoidal microstructure in the total reflection layer 20 is an obtuse angle. As in the description of the structure in fig. 2, since the projection light from the tele projector and incident perpendicularly to the screen plane is reflected on the two inclined surfaces of the total reflection layer 20, the reflected light is no longer parallel to the direction perpendicular to the screen plane. Thereby making the total reflection layer 20 having a trapezoidal microstructure have the effect of diffusing the projection light.

In fig. 13, the angle between the projected light and the inclined plane of the total reflection layer 20 is σ, the angle between the outgoing light reflected by the inclined plane and the normal direction perpendicular to the screen plane is α ₁ and α ₂, where α ₁ is α ₂, and the angle between the reflected light reflected by one inclined plane and the normal of the other inclined plane is ω, then it can be known from the geometrical relationship shown in fig. 13:

α₁＝2θ-180

Assuming that the refractive index of the material outside the inclined surface of the total reflection layer 20 is n ₁, and the refractive index of the material constituting the total reflection layer 20 is n ₂, the following relationship needs to be satisfied in order to satisfy the total reflection condition:

Therefore, the angle θ between the two inclined surfaces of the total reflection layer 20 is required to satisfy the following relationship:

The included angle alpha ₁ between the emergent ray and the normal direction vertical to the screen satisfies the following conditions:

Therefore, an appropriate angle θ between the two inclined surfaces of the trapezoidal total reflection layer 20 can be confirmed from the refractive index n ₂ of the material constituting the total reflection layer 20 and the refractive index n ₁ of the material outside the inclined surfaces of the total reflection layer 20, and the diffusion angle obtained by the total reflection layer 20 can be calculated.

Fig. 14 illustrates light intensity curves of the projected light reflected by the two inclined surfaces of the total reflection layer 20, each of the projected light reflected by the two inclined surfaces has a light intensity curve, as shown in fig. 14, which has a light intensity peak at ± γ, respectively, and a new curve varying with the angle of the outgoing light is obtained after superposition, where γ indicates angles α ₁ and α ₂ between the outgoing light reflected by the inclined surfaces and the normal direction perpendicular to the screen plane, and the curve after superposition illustrates the diffusion effect of the outgoing light reflected by the two inclined surfaces, i.e., the viewing angle of the projection screen is increased.

As can be seen from the above description of the structure, principle, etc. of the projection screen of the present invention, the projection screen of the present invention is used in cooperation with a long-focus projector, so that the emergent light reflected by the total reflection layer has a diffusion angle. Meanwhile, the total reflection layer is used together with diffusion materials such as a diffusion layer or a bulk diffusion film formed on the surface of the screen, so that the visual angle of the screen can be effectively enlarged.

In addition, the trapezoidal microstructure is used in the total reflection layer, so that environmental light rays incident at multiple angles are considered, the black light absorption layer can absorb more environmental light rays, and the contrast of the screen can be improved more obviously.

it should be understood by those skilled in the art that various modifications, combinations, sub-combinations and changes may be made within the scope of the appended claims or their equivalents depending on design requirements and other factors.