CN110750029B

CN110750029B - Projection screen

Info

Publication number: CN110750029B
Application number: CN201810734548.7A
Authority: CN
Inventors: 张红秀; 王霖; 王杰; 李屹
Original assignee: Appotronics Corp Ltd
Current assignee: Shenzhen Appotronics Corp Ltd
Priority date: 2018-07-06
Filing date: 2018-07-06
Publication date: 2022-01-04
Anticipated expiration: 2038-07-06
Also published as: CN110750029A; WO2020007056A1

Abstract

The utility model provides a projection screen, projection screen contains the reflection stratum, fresnel structure layer and the substrate layer that set gradually, the thickness of reflection stratum is 7nm-25 nm. According to the invention, the thickness of the reflecting layer in the projection screen is reduced, the transmittance of the reflecting layer is increased, and the light absorbing layer is not required to be selectively coated on the Fresnel structure layer, so that the ambient light in all directions can be absorbed, and the effect of high contrast is achieved; and the thickness of the reflecting layer is reduced, so that the film coating cost is saved, and the process difficulty and the screen cost are reduced.

Description

Projection screen

Technical Field

The present invention relates to a projection screen, and more particularly, to a projection screen with high contrast.

Background

Projection systems have been developed in recent years that achieve large screen projection of over 100 inches with a projector and screen distance of 50 cm. The projection system can overcome the limitation of installation space. However, when the projection system is installed in an environment where a large amount of stray light exists, such as a bright living room, there are problems in displaying an image on the projection screen, and the screen reflects ambient light, thereby causing interference with signal light, and it is difficult to obtain a good contrast. For the screen with the prism structure, in order to solve the above problems, a light absorbing layer needs to be coated on one surface of the protrusion of the prism structure facing the roof ambient light, and a reflecting layer needs to be coated on one surface facing the projection light.

For example, the technical solutions disclosed in patent documents KR1256594B1 and JP4047172 are both to selectively coat a light absorbing layer on a specific region of a fresnel structure in a reflective screen, in such a way that only ambient light having a large difference in direction from projection light can be absorbed, and ambient light having the same direction as the projection light cannot be absorbed, and the manufacturing method is complicated and costly.

Disclosure of Invention

The technical problem to be solved by the invention is to provide a projection screen aiming at the defects of the prior art, the light transmittance of a reflecting layer is increased by reducing the thickness of the reflecting layer in the projection screen, and ambient light in all directions can be absorbed without selectively coating a light absorption layer on a Fresnel structure layer, so that the effect of high contrast is achieved; and the thickness of the reflecting layer is reduced, so that the film coating cost is saved, and the process difficulty and the screen cost are reduced.

The technical problem to be solved by the invention is realized by the following technical scheme:

the invention provides a projection screen which comprises a reflecting layer, a Fresnel structure layer and a base material layer which are sequentially arranged, wherein the thickness of the reflecting layer is 7nm-25 nm.

In order to absorb ambient stray light, the projection screen is provided with a light absorbing layer on the side far away from the incident side of the projection light.

Preferably, the outer surface of the substrate layer is provided with a surface diffusion structure.

Preferably, the projection screen further comprises a diffusion layer arranged on the incident side of the projection light, the diffusion layer is a diffusion layer or a surface diffusion layer, and the diffusion layer and the base material layer are bonded by arranging a transparent adhesive.

Preferably, projection screen contains edge reflection stratum, fresnel structure layer and the substrate layer that projection light's incident direction set gradually, the surface of reflection stratum sets up a diffusion structure, the substrate layer is black.

In order to increase the divergence angle of the emergent ray, the surface diffusion structure is a concave-convex structure which is formed by sand blasting or photoetching; the thickness of the concave-convex structure along the normal direction of the surface where the concave-convex structure is located is 1-10 mu m; the concave-convex structure has a size of 2-40 μm along a surface parallel to the concave-convex structure.

Preferably, the thickness of the concave-convex structure along the normal direction of the surface is 3-6 μm; the concave-convex structure has a size of 6-24 μm along a surface parallel to the concave-convex structure.

Preferably, the thickness of the Fresnel structure layer is 10-100 μm. The thickness of the reflecting layer is 8nm-13 nm.

Preferably, the reflective layer has a reflectivity of 18% to 50%, preferably 20% to 30%.

In summary, the thickness of the reflecting layer in the projection screen is reduced, the transmittance of the reflecting layer is increased, and the light absorbing layer is not required to be selectively coated on the fresnel structure layer, so that the ambient light in all directions can be absorbed, and the high-contrast effect is achieved; and the thickness of the reflecting layer is reduced, so that the film coating cost is saved, and the process difficulty and the screen cost are reduced.

The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

Drawings

FIG. 1 is a schematic diagram showing the relationship between the reflectivity of a reflective layer and the thickness of the reflective layer;

FIG. 2 is a schematic diagram of a projection screen according to an embodiment of the present invention;

FIG. 3 is a schematic structural diagram of a second projection screen according to an embodiment of the present invention;

fig. 4 is a schematic structural diagram of a third projection screen according to an embodiment of the invention.

Detailed Description

The invention provides a projection screen which is used for reflecting projection light rays to a field range of a viewer. In order to increase the divergence angle of the outgoing light rays, the projection screen further comprises a diffuser layer arranged on the incident side of the projection light rays. In order to absorb ambient stray light, the projection screen is provided with a light-absorbing layer on the side remote from the incident side. When the projection screen is used, the projection light enters from the diffusion layer, is reflected by the reflection layer and then exits from the diffusion layer, so that a viewer can see the picture.

The reflecting layer is an aluminum reflecting layer, a silver reflecting layer and the like, and can be prepared in a vacuum coating mode such as magnetron sputtering or evaporation.

The Fresnel structure layer is formed by adopting a roll-to-roll process and curing of the photosensitive adhesive.

The substrate layer can adopt transparent polymers such as PET (polyethylene terephthalate), PC (polycarbonate), PVC (polyvinyl chloride), PMMA (polymethyl methacrylate) and the like.

The diffusion layer may be a diffusion layer or a surface diffusion layer, preferably a surface diffusion layer. The diffusion layer contains volume scattering particles; one side of the surface diffusion layer is provided with a surface diffusion structure.

The light absorption layer is used for absorbing the ambient light penetrating through the reflection layer and improving the image contrast, such as carbon black, aniline black and the like.

FIG. 1 is a diagram illustrating the relationship between the thickness of a reflective layer and the reflectivity. The reflective layer of fig. 1 employs an aluminum reflective layer, and as shown in fig. 1, when the thickness of the aluminum film is greater than about 55nm, the reflectance and transmittance of the aluminum film are substantially stable, and when the thickness of the aluminum film is less than about 55nm, the reflectance of the aluminum film decreases as the thickness of the aluminum film decreases, and the transmittance increases as the thickness of the aluminum film decreases. I.e. the reflectivity of the projection screen can be controlled by varying the thickness of the reflective layer.

Table 1 shows the optical parameters of the projection screen for different reflective layer thicknesses. After the experiment, the factors such as the reflectivity, the gain and the contrast of the projection screen are comprehensively considered, in order to enable the projection screen to display a picture with high contrast, specifically, when the reflectivity is lower than 18%, the gain is too low, and the brightness is too dark, and when the reflectivity is higher than 50%, the contrast is too poor, therefore, in the invention, the reflectivity of the reflecting layer is 18% -50%, the thickness of the reflecting layer is 7nm-25nm, preferably, the reflectivity is 20% -30%, and the thickness of the reflecting layer is 8nm-13 nm.

TABLE 1

Thickness/nm of the reflecting layer	Reflectivity of light	Gain of	Contrast ratio
				8	20％	0.9	14.2
10	22％	1.1	13.6
				13	30％	1.4	11.1
20	45％	1.9	9.3
				36	79％	3.1	6.2
55	92％	4.6	5.5

The structure and production process of the projection screen of the present invention will be further described with reference to specific examples.

Example one

Fig. 2 is a schematic structural diagram of a projection screen according to an embodiment of the invention. As shown in fig. 2, in the present embodiment, the projection screen includes a diffusion layer 101, a base material layer 102, a fresnel structure layer 103, a reflection layer 104, and a light absorption layer 105, which are sequentially disposed along the incident direction of the projection light.

Specifically, the diffusion layer 101 is a surface diffusion layer, one surface of the surface diffusion layer has a microstructure (surface diffusion structure), one surface of the surface diffusion layer without the microstructure is bonded to a substrate layer 102 (transparent PET) by using a transparent adhesive, and one surface of the substrate layer 102 far from the diffusion layer 101 is coated with a photosensitive adhesive (such as a UV curing adhesive), wherein the thickness of the photosensitive adhesive is 10 μm to 100 μm, preferably 20 μm to 50 μm. The Fresnel structure is transferred to the surface of the base material layer 102 coated with the photosensitive adhesive by a roll-to-roll process and is cured by a UV curing process to form the Fresnel structure layer 103 with the thickness of 10-100 mu m, the roll-to-roll transfer and the UV curing are mature processes, and specific process parameters are not described.

The present embodiment employs an aluminum reflective layer as the reflective layer 104. Placing the roll material (composed of diffusion layer 101, substrate layer 102, Fresnel structure layer 103) with Fresnel structure in a roll-to-roll vacuum evaporation coating machine, and vacuumizing with vacuum degree of 10^-3Pa-10^-4And Pa, heating the aluminum wire at the temperature of 1200-1300 ℃ to melt and evaporate the aluminum wire into a gaseous state, wherein the unreeling speed and the reeling speed of the coil stock, namely the film coating speed, are 500 m/min. And depositing gaseous aluminum particles on one surface of the coil material containing the Fresnel structure layer, cooling and reducing to obtain the aluminum film with the thickness of about 13 nm. The reflectance of the aluminum film was measured to be 30% by a spectrophotometer.

A light absorbing layer 105, such as carbon black, nigrosine, or the like, covers the reflective layer 104. The light absorption layer can be sequentially coated on the thread surface of the reflection layer 104 with the Fresnel structure by adopting a simple and easy-to-operate brushing coating mode and the like, the process is simple, and the manufacturing cost of the screen can be reduced.

In this embodiment, since the reflective layer 104 and the light absorbing layer 105 are covered on the entire fresnel structure layer 103, the projection screen can absorb the ambient light in all directions.

Example two

Fig. 3 is a schematic structural diagram of a second projection screen according to an embodiment of the invention. As shown in fig. 3, the present embodiment is different from the first embodiment in that the projection screen is not provided with a diffusion layer separately, but a surface diffusion structure is processed on the outer surface of the substrate layer 202, and the diffusion layer is implemented by the surface diffusion structure.

Specifically, in the present embodiment, the projection screen includes a substrate layer 202, a fresnel structure layer 203, a reflection layer 204, and a light absorption layer 205, which are sequentially disposed along the incident direction of the projection light.

When the projection screen is produced, a surface diffusion structure is firstly arranged on one surface of the substrate layer 202, and then the photosensitive adhesive is coated on the surface of the substrate layer 202 without the surface diffusion structure, and then the projection screen can be obtained through the same production process as the first embodiment.

The embodiment simplifies the structure of the projection screen and reduces the production process difficulty and the screen cost.

EXAMPLE III

Fig. 4 is a schematic structural diagram of a third projection screen according to an embodiment of the invention. As shown in fig. 4, in this embodiment, the projection screen includes a reflective layer 304, a fresnel structure layer 303, and a substrate layer 302 sequentially disposed along the incident direction of the projection light. The reflective layer 304 has a thickness of 12nm and a reflectivity of 25%.

In this embodiment, no light absorbing layer is separately provided, and the base material layer 302 is black in color in order to absorb the ambient light transmitted through the reflective layer.

Similarly to the second embodiment, this embodiment also does not separately provide a diffusion layer, but provides a surface diffusion structure on the outer surface of the reflective layer 304, and the surface diffusion structure is used to realize the function of the diffusion layer.

The surface diffusion structure described in the above embodiments is a concave-convex structure, which can be formed by sandblasting, photolithography, or the like, and the thickness of the concave-convex structure along the normal direction of the surface on which the concave-convex structure is located is 1 μm to 10 μm, preferably 3 μm to 6 μm; the relief structure has a dimension parallel to its surface of 2 μm to 40 μm, preferably 6 μm to 24 μm. Through the concave-convex structure, light reflected by the reflecting layer 304 can be uniformly diffused in a conical angle of 15 degrees, and speckles are eliminated.

Claims

1. The projection screen is characterized by comprising a reflecting layer, a Fresnel structure layer and a substrate layer which are sequentially arranged along the incident direction of projection light, wherein the substrate layer is black, the thickness of the reflecting layer is 7nm-25nm, and the reflectivity of the reflecting layer is 18% -50%.

2. A projection screen according to claim 1 wherein the projection screen is provided with a light absorbing layer on the side remote from the side on which the projection light is incident.

3. The projection screen of claim 2 wherein the outer surface of the substrate layer is provided with a face diffusion structure.

4. The projection screen of claim 2 further comprising a diffuser layer disposed on the incident side of the projection light, wherein the diffuser layer is a diffuser layer or a surface diffuser layer, and wherein the diffuser layer is bonded to the substrate layer by disposing a transparent adhesive.

5. A projection screen according to claim 1 wherein the outer surface of the reflective layer is provided with a surface diffusing structure.

6. The projection screen of claim 3 or 5 wherein the surface diffusing structure is a relief structure having a thickness along a direction normal to its surface of from 1 μm to 10 μm; the concave-convex structure has a size of 2-40 μm along a surface parallel to the concave-convex structure.

7. The projection screen of claim 6 wherein the relief structure has a thickness along the direction of the surface normal of the relief structure of from 3 μm to 6 μm; the concave-convex structure has a size of 6-24 μm along a surface parallel to the concave-convex structure.

8. The projection screen of claim 1 wherein the fresnel structure layer has a thickness of 10 μ ι η to 100 μ ι η.

9. The projection screen of claim 1 wherein the reflective layer has a thickness of 8nm to 13 nm.

10. The projection screen of claim 1 wherein the reflective layer has a reflectivity of 20% to 30%.