A rear projection screen and method of making the same

Abstract

The application discloses a back projection screen and a manufacturing method thereof. The back projection screen comprises a protective layer, a CPC microstructure layer and a substrate. The CPC microstructure layer is arranged above the substrate. The protective layer is arranged above the CPC microstructure layer. A plurality of CPC cavities are arranged on the CPC microstructure layer and uniformly distributed along the top surface of the substrate. The entrance of the CPC cavity is upward, and the exit is downward. By arranging the plurality of CPC cavities, most of the incident light can be imaged through the exit, and the external environment light and the secondary reflection light of the imaging screen are not easy to pass through the CPC cavity, thereby effectively solving the problem that the existing back projection screen is affected by the external environment light and the secondary reflection light of the imaging screen, and the imaging effect is poor.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of projection screens, in particular to a rear projection screen and a manufacturing method thereof. BACKGROUND

[0002] A rear projection splicing wall is a large screen formed by splicing multiple display units, thereby realizing a display application of a super large screen and super high resolution display. Figure 1 As shown in the figure, a single display unit is mainly composed of a box body, a projector and an imaging screen; the box body generally further comprises a mirror assembly. The imaging screen is responsible for receiving light emitted from the projector; the mirror assembly reflects the light and projects it onto the imaging screen to form an image. Figure Two As shown in the figure, the basic components of the currently commonly used rear projection screen are a Fresnel lens and an imaging screen; the Fresnel lens emits the divergent light emitted from the projector in parallel to the imaging screen, and the imaging screen uses optical microstructures to scatter and image the incident light.

[0003] In order to reduce the thickness of the system, the box body of the current rear projection splicing wall generally adopts a one-time reflection structure, that is, the light signal emitted from the projector is reflected by the mirror and then incident on the imaging screen to form an image. Figure Three As shown in the figure, part of the incident light on the imaging screen will be reflected back to the mirror and then reflected again to the imaging screen through the mirror, forming a ghost image of secondary reflection, which interferes with the normal display picture, reduces the display contrast and affects the viewing effect. In addition, the ambient light will also partially penetrate the imaging screen from the front of the system, reflect inside the lens and the box body to form stray light, which is incident back to the imaging screen, thereby seriously reducing the picture contrast and resulting in poor viewing effect. SUMMARY

[0004] Therefore, the purpose of the present application is to provide a rear projection screen and a manufacturing method thereof, which can solve the problem of poor imaging effect of the existing rear projection screen.

[0005] To achieve the above technical purpose, the first aspect of the present application provides a rear projection screen, comprising: a protective layer, a CPC microstructure layer and a substrate.

[0006] The CPC microstructure layer is covered above the substrate;

[0007] The protective layer is covered above the CPC microstructure layer;

[0008] The CPC microstructure layer is provided with a plurality of CPC cavities uniformly laid along the top surface of the substrate;

[0009] The incident port of the CPC cavity faces upward, and the exit port faces downward.

[0010] Further, the CPC cavity is filled with high refractive index transparent material inside;

[0011] The low refractive index black material is filled between the adjacent CPC cavities.

[0012] Further, the CPC microstructure layer is further provided with a substrate;

[0013] The substrate is integrally connected with the CPC cavity;

[0014] The substrate is made of the same high refractive index transparent material as the CPC cavity.

[0015] Further, the maximum acceptance angle of the CPC cavity is 20-30°.

[0016] Further, the thickness of the CPC microstructure layer is 1mm±0.1mm.

[0017] Further, the exit port radius of the CPC cavity is 0.05-0.15mm.

[0018] Further, the protective layer is a PET protective film with a thickness of 0.05-0.125mm.

[0019] Further, the substrate is made of one or more of PMMA, PC and styrene copolymer.

[0020] Further, it further comprises an anti-glare film;

[0021] The anti-glare film is laid under the substrate.

[0022] The second aspect of the application provides a manufacturing method of a back projection screen, which is applied to manufacture the back projection screen of any one of the above aspects;

[0023] The method comprises the following steps:

[0024] S1, roll the high refractive index transparent material into a semi-finished film with CPC microstructure by a CPC microstructure roller;

[0025] S2, fill the low refractive index black material on the semi-finished film to form a CPC microstructure layer;

[0026] S3, respectively paste the substrate and the protective layer on the CPC microstructure layer.

[0027] From the above technical solutions can be seen, the application provides a kind of back projection screen and its manufacturing method, which comprises: protective layer, CPC microstructure layer and substrate;The CPC microstructure layer covers on the substrate;The protective layer covers on the CPC microstructure layer;A plurality of CPC cavities are arranged on the CPC microstructure layer, which are uniformly laid along the top surface of the substrate;The entrance of the CPC cavity is towards the upper, and the exit is towards the lower. By being provided with a plurality of CPC cavities, most of the incident light can be imaged through the exit, and the ambient light and the secondary reflected light of the imaging screen are not easy to pass through the CPC cavity, effectively solve the problem that the existing back projection screen is affected by the ambient light and the secondary reflected light of the imaging screen, and the imaging effect is poor. BRIEF DESCRIPTION OF DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present application or prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0029] Figure 1 The existing single display unit provided by the present application is shown in the figure;

[0030] Figure 2 The basic component diagram of the existing back projection screen provided by the present application does not contain mirror assembly;

[0031] Figure 3 The existing back projection screen provided by the present application is shown in the figure;

[0032] Figure 4 The hierarchical structure diagram of the back projection screen provided by the present application is shown in the figure;

[0033] Figure 5 The enlarged view of the CPC microstructure layer of the back projection screen provided by the present application is shown in the figure;

[0034] Figure 6 The CPC structure provided by the present application converges light within the receiving angle range, as shown in the figure;

[0035] Figure 7 The CPC structure provided by the present application reflects light outside the receiving angle range, as shown in the figure;

[0036] Figure 8 The CPC structure provided by the present application is shown in the figure when the maximum receiving angle is incident;

[0037] Figure 9 A related symbol diagram in the standard CPC structure provided by the embodiment of the present application;

[0038] Figure 10 A light ray diagram of the vertical incidence screen part in a back projection screen provided by the embodiment of the present application;

[0039] Figure 11 A stray light diagram of secondary reflection in a back projection screen provided by the embodiment of the present application;

[0040] Figure 12 A diagram when the ambient environment light irradiates to the surface of the screen in a back projection screen provided by the embodiment of the present application;

[0041] Figure 13 A manufacturing process diagram in a manufacturing method of a back projection screen provided by the embodiment of the present application;

[0042] Figure 14 Another manufacturing process diagram in a manufacturing method of a back projection screen provided by the embodiment of the present application.

[0043] In the figure: 10, an imaging screen; 20, a box body; 30, a mirror; 40, a projector; 50, a Fresnel lens; 1, a protective layer; 2, a CPC microstructure layer; 3, a substrate; 4, an anti-glare film; 5, a CPC microstructure roller; 6, a flat roller; 7, an ultraviolet lamp; 21, a CPC cavity; 22, a low refractive index black material; 23, a base; 24, a high refractive index transparent material. DETAILED DESCRIPTION

[0044] The technical solutions of the embodiments of the present application will be described clearly and completely below with reference to the drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the present application.

[0045] In the description of the embodiments of the present application, it should be noted that the terms “center”, “upper”, “lower”, “left”, “right”, “vertical”, “horizontal”, “inner”, “outer” and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the embodiments of the present application. In addition, the terms “first”, “second”, “third” are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0046] In the description of the embodiments of the present application, it should be noted that unless specifically defined and limited, the terms "mounting", "connecting", "connecting" should be understood in a broad sense, for example, it can be fixedly connected, or it can be replaceably connected, or it can be integrally connected, it can be mechanically connected, or it can be electrically connected, it can be directly connected, or it can be indirectly connected through an intermediate medium, it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0047] Please refer to Figure 4 With Figure 5 , the first aspect of the present application provides a back projection screen, comprising: a protective layer 1, a CPC microstructure layer 2 and a substrate 3; the CPC microstructure layer 2 is covered on the substrate 3; the protective layer 1 is covered on the CPC microstructure layer 2; a plurality of CPC cavities 21 are arranged on the CPC microstructure layer 2, which are uniformly laid along the top surface of the substrate 3; the entrance of the CPC cavity 21 is upward, and the exit is downward.

[0048] Specifically, the CPC cavity 21 forms a CPC (Compound Parabolic Concetrator, Compound Parabolic Concentrator) structure on both sides; as Figure 6 As shown, it can collect and converge the light within the set receiving angle range to the receiving window of the CPC cavity 21; as Figure 7 With Figure 8 As shown, the light outside the receiving angle range is reflected back by the CPC cavity 21 and cannot reach the receiving window.

[0049] Therefore, in the CPC microstructure layer 2, only the projector incident light smaller than the set incident angle can be transmitted through the CPC microstructure layer 2 to form an image, and the secondary reflected light and stray light larger than the set incident angle are shielded and cannot be transmitted. Thus, the influence of secondary reflected light and external environmental light on the display effect of the imaging screen 10 can be reduced

[0050] In one embodiment, the CPC cavity 21 is filled with a high refractive index transparent material 24; the adjacent CPC cavities 21 are filled with a low refractive index opaque low refractive index black material 22. By the high refractive index transparent material 24 and the low refractive index opaque low refractive index black material 22, the light incident to the cavity wall and the incident angle greater than the corresponding total reflection angle will be reflected, forming a CPC reflection cavity. The substrate 3 can be made of one or more of PMMA (polymethyl methacrylate), PC (polycarbonate), styrene copolymer and other optical materials, mainly playing the role of supporting and scattering light.

[0051] In another embodiment, in order to increase the probability of light projection into the CPC cavity 21, a substrate 23 is further arranged on the CPC microstructure layer 2; the substrate 23 is integrally connected with the CPC cavity 21; the substrate 23 is made of the same high refractive transparent material 24 as the CPC cavity 21.

[0052] Specifically, as shown in Figure 10 the majority of the projector light is parallelized by the Fresnel lens 50 and then vertically incident on the imaging screen 10; a part of the incident light directly passes through the exit port of the CPC cavity 21, and another part of the incident light is incident on the cavity wall in the CPC cavity 21 and undergoes total reflection, and then is emitted from the exit port; both parts of the light are further scattered by the substrate 3 to form an image.

[0053] As shown in Figure 11 a small part of the projector light is reflected to the mirror 30 and the inside of the box 20 by the inner surface of the Fresnel lens 50, forms stray light after secondary reflection, and is then reflected or absorbed; among them, the part that can be reflected back to the imaging screen 10 is incident on the imaging screen 10 through the Fresnel lens 50, and will be divided into three parts:

[0054] One part, the light with an incident angle smaller than the corresponding total reflection angle of the CPC cavity 21 cannot form reflection and will be directly absorbed by the low refractive black material 22, and will not affect the imaging effect of the imaging screen 10;

[0055] Another part, the light with an incident angle greater than the corresponding total reflection angle of the CPC cavity 21 but exceeding the maximum receiving angle θ max will be reflected in the CPC cavity 21, and then or in the process of reflection, it cannot satisfy the total reflection condition and is absorbed, or is reflected back to the inside of the box 20 again, continues to reflect and absorb, and also will not affect the imaging effect of the imaging screen 10;

[0056] The remaining very small part, the light with an incident angle greater than the corresponding total reflection angle and smaller than the maximum receiving angle, will be emitted from the exit port.

[0057] Therefore, by arranging the CPC cavity 21, only a very small part of the secondary reflected stray light can be reflected back onto the imaging screen 10, greatly reducing the influence of the secondary reflected stray light.

[0058] As shown in Figure 12As shown, the ambient light irradiates to the surface of the imaging screen 10, most of which is absorbed by the low refractive black material 22 on the CPC microstructure layer 2 after penetrating the substrate 3, a small part penetrates the exit of the CPC cavity 21, or is absorbed because it does not reach the total reflection condition, or finally enters the mirror 30 and the inside of the box 20, forming secondary reflection and other stray light, which is finally completely absorbed after multiple reflections and cannot be emitted to the imaging screen 10, and will not affect the imaging effect of the imaging screen 10, so the ambient light is basically absorbed. Among them, the proportion of ambient light directly absorbed by the low refractive black material 22 is related to the light collection rate C of the CPC cavity 21.

[0059] In a more specific embodiment, in this scheme, the CPC cavity 21 is a standard CPC structure, and the maximum receiving angle is 20° to 30°.

[0060] Specifically, in the standard CPC structure, please refer to Figure 9 According to the CPC principle, under the condition that the maximum receiving angle θ max and the exit radius a' are determined, other parameters can be calculated by the following formula:

[0061]

[0062] In addition, there is the following relationship:

[0063]

[0064] Therefore:

[0065] Wherein, a is the entrance radius. C is the light collection rate of the CPC cavity 21.

[0066] Considering the manufacturing process and screen resolution requirements, the exit radius of the CPC cavity 21 is in the range of 0.05mm to 0.15mm, which is more appropriate. The maximum receiving angle θ max Although the smaller the angle, the better the shielding effect of stray light, but because the refractive index of the actual available material is limited, it affects the selection of the cavity total reflection angle. In addition to considering the incident angle of stray light, the refractive index of the two materials inside and outside the cavity and the CPC optical microstructure related parameters are determined as follows:

[0067] a) The refractive indexes of the high refractive transparent material 24 and the low refractive black material 22 used in the CPC cavity 21 are n1 and n2 respectively, according to the total reflection formula sinI0=n2 / n1, the total reflection angle I0 can be calculated;

[0068] b) The projected light from the projector 40 exits almost parallel after passing through the Fresnel lens 50, and the deviation angle is very small and negligible. Therefore, the incident light from the imaging screen 10 can be considered as perpendicular incident light. Figure 9 As shown, to ensure that all rays perpendicularly incident on the cavity wall of the CPC cavity 21 can satisfy total internal reflection, it is only necessary to set the incident angle α of the rays at the edge of the exit port to be greater than I0. According to formula (4), θ can be obtained. max >2I0-90°, taking all factors into account, θ max A value range of 20° to 30° can achieve better results.

[0069] c) The entrance radius a and length L of the CPC optical microstructure can be calculated using formulas (1) and (2).

[0070] It should be noted that the derivation process of the above formula (4) is as follows; please refer to [link / reference]. Figure 8 and Figure 9 :

[0071] According to the standard CPC structure principle, such as Figure 8 All at the maximum receiving angle θ max The incident light rays, after being reflected by CPC, will all exit through the edge point F1 of the exit aperture.

[0072] Therefore, as Figure 8 As shown, the reflected ray of the incident ray G1F2 is F2F1, and F2J is the normal at point F2. Therefore, ∠O2F2J=∠JF2F1.

[0073] Clearly, △O2OF2 is a right triangle, therefore ∠O2F2J=(90°-θ) max ) / 2, we get:

[0074]

[0075] Therefore, we get:

[0076] In one embodiment, the overall thickness of CPC microstructure layer 2 is 1 mm ± 0.1 mm.

[0077] Furthermore, the protective layer 1 is a PET protective film with a thickness of 0.05 to 0.125 mm. The overall thickness of the substrate 3 is 2 mm ± 0.1 mm.

[0078] Furthermore, it also includes an anti-glare film 4; the anti-glare film 4 is laid under the substrate 3.

[0079] Specifically, the anti-glare film 4 is a PET film with a thickness of 0.15 to 0.3 mm, and the surface of the film is treated by anti-glare and hardening. The film mainly has anti-glare and protection functions. The AG anti-glare coating can be directly used on the surface of the substrate 3 to perform anti-glare and hardening treatment.

[0080] The second aspect of the embodiments of the present application provides a manufacturing method of a back projection screen, which is applied to manufacturing the back projection screen in any of the above embodiments. Please refer to Figures 13 to 14 .

[0081] The method comprises the following steps:

[0082] S1, roll the high refractive transparent material 24 into a semi-finished film with CPC microstructure by the CPC microstructure roller 5.

[0083] Specifically, the high refractive transparent material 24 is first laid flat, and then the two surfaces of the high refractive transparent material 24 are rolled by the CPC microstructure roller 5 and the flat roller 6 respectively. Then, the CPC cavity 21 is formed on the surface rolled by the CPC microstructure roller 5, thereby forming the semi-finished film with CPC microstructure.

[0084] S2, fill the low refractive black material 22 on the semi-finished film to form the CPC microstructure layer 2.

[0085] The high refractive transparent material 24 can be, for example, zirconium-containing multifunctional acrylate, brominated aromatic monomer acrylate material, etc. The low refractive black material 22 can be fluorine-based acrylate material added with nano-carbon black, etc. The low refractive black material 22 is filled on the microstructure surface of the semi-finished film by precise coating or inkjet technology, and is solidified to form the CPC microstructure layer 2.

[0086] S3, respectively paste the substrate 3 and the protective layer 1 on the CPC microstructure layer 2 to complete the manufacturing of the back projection screen. During the manufacturing process, the side of the CPC microstructure layer 2 with the CPC cavity 21 can be irradiated by the ultraviolet lamp 7 at the same time.

[0087] The above is the preferred embodiment of the present application, and is not used to limit the present application. Although the present application is described in detail with reference to the examples, those skilled in the art can modify the technical solutions described in the examples or replace some of the technical features with equivalent ones, but any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A rear projection screen, characterized by Comprising: a protective layer (1), a CPC microstructure layer (2) and a substrate (3); the CPC microstructure layer (2) is covered on the substrate (3); the protective layer (1) is covered on the CPC microstructure layer (2); a plurality of CPC cavities (21) are arranged on the CPC microstructure layer (2) and evenly laid along the top surface of the substrate (3); the incident port of the CPC cavity (21) faces upward, and the exit port faces downward; the CPC cavity (21) is filled with high refractive index transparent material (24) inside; low refractive index black material (22) is filled between adjacent CPC cavities (21); the CPC microstructure layer (2) is also provided with a substrate (23); the substrate (23) is integrally connected with the CPC cavity (21); the substrate (23) is made of the same high refractive index transparent material (24) as the CPC cavity (21); the maximum acceptance angle of the CPC cavity (21) is 20° to 30°; the exit port radius of the CPC cavity (21) is 0.05mm to 0.15mm.

2. The rear projection screen of claim 1, wherein, The thickness of the CPC microstructure layer (2) is 1mm±0.1mm.

3. The rear projection screen of claim 2, wherein, The protective layer (1) is a PET protective film with a thickness of 0.05 to 0.125mm.

4. The rear projection screen of claim 1, wherein, The substrate (3) is made of one or more of PMMA, PC and styrene copolymer.

5. The rear projection screen of claim 1, wherein, It also includes an anti-glare film (4); the anti-glare film (4) is laid under the substrate (3).

6. A method of making a rear projection screen, characterized by It is applied to the manufacture of the back projection screen of any one of claims 1 to 5; The method comprises the following steps: S1, roll the high refractive index transparent material (24) into a semi-finished film with CPC microstructure by a CPC microstructure roller (5); S2, fill the low refractive index black material (22) on the semi-finished film to form the CPC microstructure layer (2); S3, respectively paste the substrate (3) and the protective layer (1) on the CPC microstructure layer (2).

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