Projection screen, method for manufacturing the same, and projection system

Abstract

This invention discloses a projection screen 1, a manufacturing method, and a projection system. The Zenki projection screen 1 includes a diffusion layer 11, a Fresnel structure layer 12, and a wavelength-selective reflective layer F located on at least a portion of the Fresnel structure 121 of the Fresnel structure layer 12. The wavelength-selective reflective layer F selectively reflects projection light emitted from a projection device 2 while significantly reducing the reflectance of light in other wavelength bands. This allows for a black appearance when the projection device 2 is turned off and a bright display when the projection device 2 is turned on, thereby significantly improving the contrast of the projected image.

Description

Technical Field

[0001] This application claims priority based on a Chinese patent application filed with the Chinese Patent Office on December 29, 2022, with an application number of 202211716475.1 and an invention title of "Projection Screen and Projection System", and incorporates all of its disclosures herein. Also, this application claims priority based on a Chinese patent application filed with the Chinese Patent Office on December 29, 2022, with an application number of 202211716324.6 and an invention title of "Projection Screen and Projection System", and incorporates all of its disclosures herein. This application claims priority based on a Chinese patent application filed with the Chinese Patent Office on February 10, 2023, with an application number of 202310107687.8 and an invention title of "Projection Screen, Its Manufacturing Method and Projection System", and incorporates all of its disclosures herein.

[0002] The present invention relates to the technical field of projection, and particularly to projection screens, their manufacturing methods and projection systems.

Background Art

[0003] With the popularization of laser display products, the market for laser TVs, which are large-screen products replacing liquid crystal and organic electroluminescent (EL for short) TVs, is expanding rapidly.Conventional front-projection type projection systems can usually be used in combination with a projection screen. A projection beam is emitted from a projection device, the projection beam is incident on the projection screen, and after reflection by the projection screen, it is incident on the human eye, and a projection image is observed.

Summary of the Invention

Problems to be Solved by the Invention

[0004] White matte projection screens can reflect light from a light source evenly in all directions and are sold at low cost. However, white matte projection screens are susceptible to ambient light when viewed in bright environments and are unsuitable for movies and other videos that frequently feature dark scenes. To address this problem, there are screens that are colored to absorb ambient light and reduce its brightness. However, colored projection screens also absorb light emitted from the projection source, resulting in a loss of brightness in the projected light and a decrease in image contrast. [Means for solving the problem]

[0005] A first embodiment of the present invention provides a projection screen comprising: a diffusion layer; a diffusion layer; a Fresnel structure layer located on one side of the diffusion layer and having a Fresnel structure on the surface of that side; and a wavelength selective reflective layer covering at least a portion of the surface of the Fresnel structure of the Fresnel structure layer, wherein the reflectance to light rays emitted from a projection device is higher than the reflectance to light rays of other wavelength bands.

[0006] A second embodiment of the present invention is a manufacturing step of a Fresnel structure, which has a Fresnel structure layer having a plurality of Fresnel structures on one side surface of the Fresnel structure layer, wherein the Fresnel structures have inclined surfaces and connecting surfaces that are connected to each other, A manufacturing process for a reflective layer, comprising forming a discontinuous first thin film on the inclined surface of the Fresnel structure and forming a continuous second film layer on the first thin film, The process includes a step for manufacturing a surface functional layer, in which a surface functional layer is formed on one side surface of the Fresnel structural layer having the reflective layer. The present invention provides a method for manufacturing a projection screen.

[0007] A third embodiment of the present invention is a projection device for emitting projected light rays, The projection device comprises one of the above-mentioned projection screens located on the light-emitting side, The projection device is an ultra-short-throw laser projection device, The projection device is, A three-color laser light source device for emitting three primary color laser light, A light modulation member located on the light-emitting side of the three-color laser light source device for modulating the emitted laser light of the three-color laser light source device, The present invention provides a projection system comprising a projection lens located on the light-emitting side of the aforementioned light modulation member. [Brief explanation of the drawing]

[0008] To more clearly explain the technical concepts of the embodiments of the present invention, the drawings to be used in the embodiments of the present invention will be briefly described below. Clearly, the drawings described below are merely some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these without any creative ingenuity. [Figure 1] This is a schematic diagram of the structure of a projection system according to an embodiment of the present invention. [Figure 2] This is a schematic diagram 1 of the structure of a projection screen in related technologies. [Figure 3] This is diagram 2 of the schematic structure of a projection screen in related technologies. [Figure 4] This is a schematic diagram of the structure of a projection screen according to an embodiment of the present invention. [Figure 5] This is a schematic diagram of the structure of a wavelength-selective reflective layer according to an embodiment of the present invention. [Figure 6] This is a schematic diagram 2 of the structure of a wavelength-selective reflective layer according to an embodiment of the present invention. [Figure 7] This is a reflectance curve of a wavelength-selective reflective layer for light rays of different wavelength bands according to an embodiment of the present invention. [Figure 8] This is an ambient light intensity distribution curve according to an embodiment of the present invention. [Figure 9] This is a reflectance curve of ambient light incident on a wavelength-selective reflective layer according to an embodiment of the present invention. [Figure 10] This is a relationship curve between the thickness of the semi-transparent layer and the ambient light intensity attenuation rate according to an embodiment of the present invention. [Figure 11] This is one of the relationship curves between wavelength and reflectance according to an embodiment of the present invention. [Figure 12] It is 2 of the relationship curve between wavelength and reflectivity according to an embodiment of the present invention. [Figure 13] It is 3 of the relationship curve between wavelength and reflectivity according to an embodiment of the present invention. [Figure 14] It is 4 of the relationship curve between wavelength and reflectivity according to an embodiment of the present invention. [Figure 15] It is 5 of the relationship curve between wavelength and reflectivity according to an embodiment of the present invention. [Figure 16] It is 6 of the relationship curve between wavelength and reflectivity according to an embodiment of the present invention. [Figure 17] It is 2 of the schematic structural diagram of the projection screen according to an embodiment of the present invention. [Figure 18] It is a comparison diagram of reflectivity curves at different incident angles according to an embodiment of the present invention. [Figure 19] It is 3 of the schematic structural diagram of the projection screen according to an embodiment of the present invention. [Figure 20] It is the reflectivity curve of the light ray at an incident angle of 65° by the wavelength selective reflection layer according to an embodiment of the present invention. [Figure 21] It is the reflectivity curve of the light ray at an incident angle of 10° by the wavelength selective reflection layer according to an embodiment of the present invention. [Figure 22] It is the reflectivity curve after two reflections by the wavelength selective reflection layer according to an embodiment of the present invention. [Figure 23] It is the relative intensity curve when ambient light enters the projection screen according to an embodiment of the present invention. [Figure 24] It is the relative intensity curve after the ambient light is reflected by the projection screen according to an embodiment of the present invention. [Figure 25] It is 4 of the schematic structural diagram of the projection screen according to an embodiment of the present invention. [Figure 26] It is 5 of the schematic structural diagram of the projection screen according to an embodiment of the present invention. [Figure 27] It is 6 of the schematic structural diagram of the projection screen according to an embodiment of the present invention. [Figure 28] It is 7 of the schematic structural diagram of the projection screen according to an embodiment of the present invention. [Figure 29]This is a schematic diagram of the structure of a projection screen according to an embodiment of the present invention. [Figure 30] This is a schematic diagram 9 of the structure of a projection screen according to an embodiment of the present invention. [Figure 31] This is a schematic diagram 10 of the structure of a projection screen according to an embodiment of the present invention. [Figure 32] This is diagram 3 of the schematic structure of a projection screen in related technologies. [Figure 33] This is diagram 4 of the schematic structure of a projection screen in related technologies. [Figure 34] This is a flowchart of a method for manufacturing a projection screen according to an embodiment of the present invention. [Figure 35] This is a schematic diagram 1 of the manufacturing flow of a Fresnel structure layer according to an embodiment of the present invention. [Figure 36] This is a schematic diagram 2 of the manufacturing flow of the Fresnel structure layer according to an embodiment of the present invention. [Figure 37] This is a curve showing the film thickness of a deposited film in a related technology. [Figure 38] This is a curve showing the film thickness of a film deposited according to an embodiment of the present invention. [Figure 39] This is a schematic diagram of the structure of the reflective layer during the film formation process according to an embodiment of the present invention. [Figure 40] This is a schematic diagram 2 of the structure of the reflective layer during the film formation process according to an embodiment of the present invention. [Figure 41] This is diagram 3 of the schematic structure of the reflective layer during the film formation process according to an embodiment of the present invention. [Figure 42] This is diagram 4 of the schematic structure of the reflective layer during the film formation process according to an embodiment of the present invention. [Figure 43] This is diagram 11 of the schematic structure of a projection screen according to an embodiment of the present invention. [Figure 44] This is a schematic diagram 12 of the structure of a projection screen according to an embodiment of the present invention. [Figure 45] This is a schematic diagram of the structure of a projection device according to an embodiment of the present invention. [Modes for carrying out the invention]

[0009] To make the above-mentioned objectives, features, and advantages of the present invention clearer and easier to understand, the present invention will be further described below with reference to the drawings and embodiments. Note that the exemplary embodiments may be implemented in multiple forms, and should not be understood as being limited to the embodiments described herein. Rather, by providing these embodiments, the present invention will be made more comprehensive and complete, and the concept of the exemplary embodiments will be comprehensively conveyed to those skilled in the art. Since the same reference numerals in the figures indicate the same or similar structures, their redundant descriptions will be omitted. All terms describing position and direction in the present invention are explained using the drawings as examples, but may be changed as necessary, and all such changes will be within the scope of protection of the present invention. The drawings of the present invention only show relative positional relationships and do not represent true proportions.

[0010] With the widespread adoption of laser display products, the market for laser TVs, which are large-screen alternatives to LCD and OLED TVs, is rapidly expanding. To achieve good brightness and display quality, it is common to use a combination of a projection device and a projection screen.

[0011] Figure 1 is a schematic diagram of the structure of a projection system according to an embodiment of the present invention.

[0012] As shown in Figure 1, the projection system comprises a projection device 2 and a projection screen 1.

[0013] The projection screen 1 is located on the light-emitting side of the projection device 2, with the viewer facing the projection screen 1. Projection light rays are emitted from the projection device 2, enter the projection screen 1, and are reflected forward after passing through the projection screen 1, so that the projected image can be observed by the viewer.

[0014] Ultra-short-throw projection devices have the characteristics of a short projection distance and a large projection screen, making them very suitable for applications in the home consumer sector. The projection system according to the embodiment of the present invention can utilize an ultra-short-throw projection device.

[0015] Conventional front projection systems use projection screens equipped with a Fresnel structure. This Fresnel structure has a specific inclination angle so that the light rays from the projection device enter the light-reflecting material on the Fresnel structure and are reflected towards the viewer, thus allowing more projected light rays to enter the viewer's eye.

[0016] Figure 2 is a schematic diagram of the structure of a projection screen in the related technology.

[0017] As shown in Figure 2, the projection screen comprises a surface layer 10, a Fresnel structure layer 12, and an adhesive layer 14, with the surface layer 10 and the Fresnel structure layer 12 being bonded to each other via the adhesive layer 14. On the side of the Fresnel structure layer 12 opposite to the surface layer 10, i.e., opposite to the viewer, there is a Fresnel structure with a light-reflecting material layer 13 formed on its surface. The light-reflecting material layer 13 is usually formed on the surface of the Fresnel structure from a light-reflecting metal such as aluminum, so when light rays are incident on the surface of the Fresnel structure, they are reflected by the light-reflecting material layer 13.

[0018] As shown in Figure 2, the projected light ray L emitted from the projection device enters the projection screen from the surface layer 10 side, and when it enters the Fresnel structure, it is reflected by the light-reflecting material layer 13 on the surface of the Fresnel structure and reflected in the direction of the viewer's position.

[0019] At the same time, ambient light C enters the projection screen from the surface layer 10 side, and similarly, when some ambient light enters the light-reflecting material layer 13 on the surface of the Fresnel structure, it is reflected by the light-reflecting material layer 13 and emitted from the projection screen. Some of this reflected ambient light can enter the human eye, thus reducing the contrast of the projected image.

[0020] To solve the above problem, typically, by coloring the film layer in the projection screen, the colored film layer can absorb the incident ambient light, thereby reducing the reflection of ambient light.

[0021] Figure 3 is a schematic diagram of the projection screen structure in the related technology.

[0022] As shown in Figure 3, the adhesive layer 14 can be colored so that ambient light is absorbed when it enters the adhesive layer 14, and light-absorbing substances such as dyes or carbon black can be mixed into the material of the adhesive layer 14. However, because the colored film layer of the projection screen absorbs light rays of the entire wavelength band, the emission efficiency of the projected light rays L after they enter the colored film layer (e.g., the adhesive layer 14) decreases, and it is not possible to improve contrast.

[0023] In view of the above, an embodiment of the present invention provides a projection screen that can significantly improve the contrast of a projected image by selectively reflecting a wavelength band of projected light emitted from a projection device and significantly reducing the reflectivity to light in other wavelength bands.

[0024] Figure 4 is a schematic diagram of the structure of a projection screen according to an embodiment of the present invention.

[0025] As shown in Figure 4, the projection screen comprises a diffusion layer 11, a Fresnel structure layer 12, and a wavelength-selective reflection layer F.

[0026] The diffusion layer 11 is the outermost film layer of the projection screen and is located on the side closest to the viewer. The diffusion layer 11 has a light diffusion effect, and the projection system according to the embodiment of the present invention may use a laser light source. Because the laser has relatively high collimation properties, the divergence angle of the projected light rays is relatively small, and the collimation of the light rays reflected by the projection screen is high, but the viewing angle becomes relatively narrow. By providing the diffusion layer 11, the emission angle of the light rays that have passed through the diffusion layer can be diversified, so that the light rays that are ultimately emitted from the projection screen have a constant divergence angle, and the viewing angle from which the viewer can view the projected image is increased. In addition, the diffusion layer 11 also eliminates laser speckle and contributes to the optimization of the projected image.

[0027] Depending on the different application scenes and manufacturing processes, each Fresnel structure 121 may form a concentric circular structure that is sequentially expanded and arranged along the radial direction, or each Fresnel structure 121 may be a linear structure that extends along the horizontal direction of the projection screen and is arranged vertically in the horizontal direction, or each Fresnel structure 121 may be a periodic structure arranged in a grid pattern, but are not limited thereto.

[0028] As shown in Figure 4, the Fresnel structure 121 comprises an inclined surface x1 and a connecting surface x2 that are connected to each other. Here, the inclined surface x1 is provided at an angle with respect to the plane on which the diffusion layer 11 is located, and the inclination angle of this inclined surface x1 is set according to the incidence angle and reflection angle of the projected light rays. The inclination angle of the inclined surface x1 satisfies the requirement that when projected light rays from the projection device are incident on the surface reflective structure of the inclined surface x1, they be reflected in the direction of the viewer. When the viewer is positioned directly in front of the projection screen, the inclined surface x1 of each Fresnel structure 121 is used to reflect the incident projected light rays directly in front of it. The connecting surface x2 is not used to reflect the projected light rays, but is used to connect the inclined surfaces x1.

[0029] The wavelength-selective reflective layer F covers at least a portion of the surface of the Fresnel structure 121 of the Fresnel structure layer 12, and the wavelength-selective reflective layer F is used to selectively reflect incident light rays. In embodiments of the present invention, the reflectance of the wavelength-selective reflective layer F for projected light rays is greater than the reflectance of light rays in other wavelength bands. As a result, by replacing the light-reflecting material layer on the surface of the Fresnel structure 121 with the wavelength-selective reflective layer F, the wavelength-selective reflective layer F can selectively reflect projected light rays from the projection device, and the reflectance of light rays in other wavelength bands is significantly reduced. This allows for a black appearance when the projection device is turned off and a bright display when the projection device is turned on, thereby significantly improving the contrast of the projected image.

[0030] As shown in Figure 4, the projected light ray L emitted from the projection device enters the projection screen from the diffusion layer 11 side and, upon entering the Fresnel structure 121, is reflected by the surface wavelength selective reflection layer F of the Fresnel structure, thereby being reflected in the direction of the viewer's position.

[0031] At the same time, ambient light C enters the projection screen from the diffusion layer 11 side. When ambient light C enters the wavelength-selective reflection layer F on the surface of the Fresnel structure 121, the wavelength-selective reflection layer F reflects only the projected light and has a low reflectivity for light in other wavelength bands. As a result, the reflection of ambient light is significantly reduced, and the contrast of the projected light is improved.

[0032] Specifically, the wavelength-selective reflective layer F achieves the effect of selectively reflecting projected light because, due to the behavior of the resonant cavity, it selects the wavelength of the light emitted towards the viewer and prevents other wavelength bands from being confined within the resonant cavity and emitted.

[0033] Figure 5 is a schematic diagram of the structure of a wavelength-selective reflective layer according to an embodiment of the present invention.

[0034] As shown in Figure 5, the wavelength-selective reflective layer F comprises at least a semi-transparent layer 131, a reflective layer 132, and a light-transmitting medium layer 133.

[0035] The semi-transparent layer 131 is located on the side closer to the diffusion layer 11 and is the closest film layer to the viewer in the wavelength-selective reflection layer F. The reflection layer 132 is located on the opposite side of the semi-transparent layer 131 from the diffusion layer 11 and is the furthest film layer from the viewer in the wavelength-selective reflection layer F, and is a certain distance away from the semi-transparent layer 131. The light-transmitting medium layer 133 is located between the semi-transparent layer 131 and the reflection layer 132 and together with the semi-transparent layer 131, the reflection layer 132, and the light-transmitting medium layer 133, it forms a resonant cavity structure.

[0036] Here, the semi-transparent and semi-reflective semi-transparent layer 131 allows the projected light ray to enter the wavelength-selective reflective layer F when it is incident on the projection screen, and also allows the projected light ray to exit from the semi-transparent layer 131 side after being oscillated and enhanced in the resonant cavity. The semi-transparent layer 131 may be a laminated structure made of at least one metal from among Al, Nb, Ag, Ti, etc., and is not limited thereto. The semi-transparent layer 131 may be manufactured by methods such as sputtering and vapor deposition, and is not limited thereto.

[0037] Furthermore, the semitransparent and semi-reflective semi-transparent light layer 131 does not necessarily have a semitransmittance and light reflectance of 50%. To explain that the semi-transparent light layer 131 can transmit a portion of the light beam and reflect a portion of it, the semi-transparent light layer 131 is usually set to transmit most or a significant portion of the light beam and reflect a small portion or a small portion of the light beam.

[0038] The reflective layer 132 has the function of reflecting light rays, is located on the side farther from the viewer, and does not need to transmit light rays, so it may be made of a reflective but non-transparent material. The reflective layer 132 can be made from materials such as aluminum, aluminum alloys, silver, or silver alloys, and the thickness of the reflective layer 132 is greater than the thickness of the semi-transparent layer 131. For example, the reflective layer 132 can be made of a laminated structure consisting of aluminum alloys such as Al and AlSi, or silver alloys such as Ag and AgPaCu, and is not limited thereto. The reflective layer 132 can be made by methods such as sputtering and vapor deposition, and is not limited thereto.

[0039] Since the length of the resonant cavity is determined by the thickness of the light-transmitting medium layer 133, the product of the refractive index and thickness of the light-transmitting medium layer 133 determines the wavelength of the light ray output from the resonant cavity towards the viewer and the wavelength that is extinguished inside. Therefore, when designing the resonant cavity, it is necessary to select a dielectric material whose product of refractive index and thickness satisfies the conditions for resonating the projected light ray emitted from the projection device. The light-transmitting medium layer 133 can be manufactured from materials such as metal oxides, nitrides, or transparent resins. For example, the light-transmitting medium layer 133 can be manufactured using metal oxides or nitrides such as TiO2, Nb2O5, ZrO2, Al2O3, ZnO2, and SiO2 by methods such as reactive sputtering, electron beam (EB) deposition, or chemical vapor deposition. Alternatively, it can be manufactured using one or more laminated structures selected from transparent resins such as PMMA, PC, and PS by wet processes such as gravure printing or die coating, and is not limited thereto.

[0040] Figure 6 is a schematic diagram of the structure of a wavelength-selective reflective layer according to an embodiment of the present invention.

[0041] In some embodiments, as shown in Figure 6, the wavelength-selective reflective layer F further comprises a first substrate 134 located opposite the semitransparent layer 131 to the light-transmitting medium layer 133. The first substrate has a support and support function as a substrate for the resonant cavity. In specific implementations, the first substrate 134 can be made from, but is not limited to, polyethylene terephthalate (PET).

[0042] The following provides a detailed explanation of the resonance behavior of the wavelength-selective reflective layer.

[0043] If the reflectance of the semitransparent layer 131 is rH, its transmittance is tH, the reflectance of the reflective layer 132 is rM, the electric field strength of the incident light incident on the wavelength-selective reflective layer is Ei, and the electric field strength of the reflected light reflected by the wavelength-selective reflective layer is Er, then

[0044]

number

[0045] This is the result. Here, the phase at which resonance is maximized is,

[0046]

number

[0047] This can be rewritten using the relationship between the lengths of the resonant cavities.

[0048]

number

[0049] Here,

number

number

[0050] As can be seen from the above relationship, by selecting a dielectric material with an appropriate refractive index as the light-transmitting medium layer and setting the thickness of the light-transmitting medium layer to an appropriate level, the reflection of projected light rays by the resonant cavity can be enhanced.

[0051] In embodiments of the present invention, a three-color laser light source can be used as the projection light source. This three-color laser light source can emit red, green, and blue lasers. By adjusting the refractive index and thickness of the light-transmitting medium layer, the reflection of the red, green, and blue lasers by the resonant cavity can be simultaneously enhanced, while the reflection of light rays in other wavelength bands can be attenuated, thereby improving the contrast of the projected light rays.

[0052] Figure 7 shows the reflectance curves of the wavelength-selective reflective layer for light rays in different wavelength bands according to an embodiment of the present invention. Here, the position of the dotted line corresponds to the central wavelength of the red laser, green laser, and blue laser. As can be seen from Figure 7, the wavelength-selective reflective layer has high reflectance at the wavelengths where the red, green, and blue lasers emitted from the projection device are located, while clearly reducing reflectance in other wavelength bands, contributing to improved contrast of the projected light rays.

[0053] In practical applications, the wavelength range of the laser emitted by a laser device is not the same, as it varies depending on the projection light source used. Typically, the emitted laser has a central wavelength, and the emission energy at the central wavelength is high. Furthermore, even if different laser devices emit lasers of the same color, the central wavelength will differ. For example, the central wavelength of a red laser can be 635 nm, 650 nm, or 643 nm, and the central wavelength fluctuates above or below this range due to manufacturing tolerances during the production of the laser device. For example, the central wavelength of a red laser can fluctuate by ±8 nm, the central wavelength of a green laser can fluctuate by 520 nm, 525 nm, or 532 nm, and the central wavelength of a blue laser can fluctuate by 445 nm or 465 nm.

[0054] Furthermore, the wavelength-selective reflective layer requires the design of the refractive index and thickness of the light-transmitting medium layer according to the required central wavelength of reflected light. In the case of an ultra-short-throw projection device, the distance between the projection device and the projection screen is small. Therefore, when light is incident from the projection device to the projection screen, some projected rays are incident at a large angle. When the light is incident at the wavelength-selective reflective layer at a large angle, a transition in the wavelength value of the selected reflected light occurs. Theoretically, the narrower the wavelength band of the reflected light selected by the wavelength-selective reflective layer, the better. At the same time, considering compatibility with the projection light source, the central wavelength of the reflected light selected by the wavelength-selective reflective layer can be within a variation range of 20 nm to 5 nm. The central wavelength of the reflected light selected by the wavelength-selective reflective layer can be red light at 635 nm, 650 nm, or 643 nm, green light at 520 nm, 525 nm, or 532 nm, or blue light at 445 nm or 465 nm, and is not limited here.

[0055] Figure 8 shows the ambient light intensity distribution curve according to an embodiment of the present invention, and Figure 9 shows the reflectance curve of ambient light incident on the wavelength-selective reflective layer according to an embodiment of the present invention. Here, the ambient light intensity distribution curve shown in Figure 8 shows the spectral distribution of the CIE standard light source D65. D65 corresponds to the average midday light in Europe / Northern Europe and is also called a daylight source. This D65 light source was used as a standard light source in calculations to demonstrate the effects of the present invention.

[0056] Comparing Figures 8 and 9, it can be seen that the intensity of ambient light is attenuated by approximately 45% after it enters the wavelength-selective reflective layer. On the other hand, Figure 7 shows that the attenuation of the three-color laser light by the wavelength-selective reflective layer is approximately 20%. Therefore, from the attenuation rates of the projected light and ambient light, it can be determined that the intensity of the projected light is (100-20) / (100-45) = approximately 1.45 times the intensity of the ambient light. As a result, the contrast of the projected light is improved.

[0057] Based on the above relationship of electric field strength, the power Pt of the reflected light reflected by the wavelength-selective reflection layer is:

number

[0058] This is the result. Here, the power of the reflected light is maximized when the sine term is 1, and minimized when the sine term is 0. Therefore, in order to improve the contrast of the projected light rays, the reflectance and transmittance of the semitransparent layer should be set so that the terms other than the sine term are minimized.

[0059] According to simulations, if the central wavelength of the red laser emitted from the projection device is 643 nm, the central wavelength of the green laser is 525 nm, and the central wavelength of the blue laser is 425 nm, then it is effective to set the thickness of the semitransparent layer 131 to within the range of 2 nm to 20 nm, the thickness of the reflective layer 132 to less than 100 nm, and the product of the thickness and refractive index of the transparent medium layer 133 to within the range of 1200 to 1400. If the reflective layer 132 is made of a metallic material, a certain thickness is required for high reflectivity, so the thickness of the reflective layer 132 needs to be greater than 50 nm.

[0060] Figure 10 shows the relationship curve between the thickness of the semi-transparent layer and the ambient light intensity attenuation rate according to an embodiment of the present invention. Here, the D65 light source spectrum was used as a representative for calculating the ambient light intensity attenuation rate. According to the inventive concept of the present invention, the higher the ambient light attenuation rate, the better the contrast.

[0061] As shown in Figure 10, when Al is used for the semi-transparent layer 131, Al for the reflective layer 132, Nb2O5 for the light-transmitting medium layer 133, and PET for the first substrate, the thickness of the semi-transparent layer at which the attenuation rate is 40% or more is approximately 3 nm to 12 nm. Since the maximum ambient light attenuation rate is obtained at a thickness of around 7 nm, when the above structure is used for the wavelength-selective reflective layer, the thickness of the semi-transparent layer 131 is set to 3 nm to 12 nm, preferably to 7 nm.

[0062] Figure 11 is the first wave of the relationship curve between wavelength and reflectance according to an embodiment of the present invention, Figure 12 is the second wave of the relationship curve between wavelength and reflectance according to an embodiment of the present invention, and Figure 13 is the third wave of the relationship curve between wavelength and reflectance according to an embodiment of the present invention. Here, Figures 11 to 13 were obtained by simulation when Al was used for the semi-transparent layer 131, Al for the reflective layer 132, Nb2O5 for the light-transmitting medium layer 133, and PET for the first substrate 134. When the thickness of the reflective layer 132 is 200 nm and the thickness of the light-transmitting medium layer 133 is constant at 609 nm, Figure 11 shows the wave of the relationship curve between wavelength and reflectance when the thickness of the semi-transparent layer 131 is 0 nm, Figure 12 shows the wave of the relationship curve between wavelength and reflectance when the thickness of the semi-transparent layer 131 is 7 nm, and Figure 13 shows the wave of the relationship curve between wavelength and reflectance when the thickness of the semi-transparent layer 131 is 30 nm.

[0063] As shown in Figure 11, when Al is used for the semi-transparent layer, if the thickness is 0, only reflection due to the refractive index difference between the light-transmitting medium layer 133 and the first substrate 134 is at play, resulting in low wavelength selectivity.

[0064] As shown in Figures 12 and 13, as the thickness of the semi-transparent layer 131 increases, the portion of the light transmitted to the resonant cavity decreases, and the portion of the light reflected by the semi-transparent layer becomes the main component. The wavelength selection function is maximized when the thickness of the semi-transparent layer 131 is 7 nm.

[0065] Figure 14 is the fourth wave-to-reflectance relationship curve related to an embodiment of the present invention, Figure 15 is the fifth wave-to-reflectance relationship curve related to an embodiment of the present invention, and Figure 16 is the sixth wave-to-reflectance relationship curve related to an embodiment of the present invention. Here, Figures 14 to 16 were obtained by simulation when Nb was used for the semi-transparent layer 131, Al for the reflective layer 132, Nb2O5 for the light-transmitting medium layer 133, and PET for the first substrate 134. When the thickness of the reflective layer 132 is 200 nm and the thickness of the light-transmitting medium layer 133 is constant at 609 nm, Figure 14 shows the wave-to-reflectance relationship curve when the thickness of the semi-transparent layer 131 is 0 nm, Figure 15 shows the wave-to-reflectance relationship curve when the thickness of the semi-transparent layer 131 is 15 nm, and Figure 16 shows the wave-to-reflectance relationship curve when the thickness of the semi-transparent layer 131 is 70 nm.

[0066] As shown in Figure 14, when Nb is used for the semi-transparent layer, if the thickness is 0, only reflection due to the refractive index difference between the light-transmitting medium layer 133 and the first substrate 134 is at play, resulting in low wavelength selectivity.

[0067] As shown in Figures 15 and 16, as the thickness of the semi-transparent layer 131 increases, the portion of the transmission component to the resonant cavity decreases. When Nb is used for the semi-transparent layer 131, unlike when Al is used, the reflective component at the metallic Nb surface, which originally has low reflectivity, becomes the main component, and the wavelength selectivity function is maximized when the thickness is around 15 nm.

[0068] As can be seen from the above, the wavelength selectivity can be altered by changing the thickness of the semi-transparent layer 131. In practical implementation, in order to maximize the wavelength selectivity, it is necessary to set an appropriate thickness for the semi-transparent layer 131 according to the specific structure used in the wavelength selectivity reflective layer F, the materials and thicknesses used in each film layer, etc.

[0069] In some embodiments, as shown in Figure 4, the wavelength-selective reflective layer F is covered on the inclined surface x1 of the Fresnel structure 121. The inclination angle of the inclined surface x1 of the Fresnel structure 121 is designed according to the incident angle of the projected light ray. The connecting surface x2 serves to connect the inclined surface x1 and does not directly receive and reflect the projected light ray. Therefore, the wavelength-selective reflective layer F covers only the inclined surface x1 of the Fresnel structure and reflects the projected light ray incident on the wavelength-selective reflective layer F on the inclined surface x1 of the Fresnel structure 121. When projected light ray or ambient light is incident on the connecting surface x2 of the Fresnel structure 121, the wavelength-selective reflective layer F is not provided on this surface, allowing the incident light ray to be directly transmitted. This prevents the light ray from being reflected and interfering with the projected light ray.

[0070] Figure 17 is a schematic diagram of the structure of a projection screen according to an embodiment of the present invention.

[0071] In some embodiments, as shown in Figure 17, the wavelength-selective reflective layer F is coated on the inclined surface x1 and connecting surface x2 of the Fresnel structure 121. Analysis tests show that the wavelength-selective reflective layer F selectively reflects different wavelengths for light rays at different incident angles.

[0072] Figure 18 is a comparison diagram of reflectance curves at different incident angles according to an embodiment of the present invention. Figure 18 shows the reflectance curves of light rays of different wavelengths when the incident angles incident on the wavelength-selective reflective layer are 0°, 30°, and 60°, respectively.

[0073] As can be seen from Figure 18, when the angle of incidence changes when light is incident on the wavelength-selective reflective layer, the wavelengths selectively reflected by the wavelength-selective reflective layer shift to shorter wavelengths. The Fresnel structure in the projection screen is designed for the angle of incidence of the projected light. The ambient light incident on the projection screen comes from various directions and, after being diffused by the diffusion layer 11, is incident on the wavelength-selective reflective layer F at multiple angles of incidence. This portion of the light is usually multiple-reflected on the surface of the wavelength-selective reflective layer, and because the angle of incidence changes constantly during the reflection process, the dependence of the wavelength-selective reflective layer on the angle of incidence allows for attenuation across the entire visible light band after multiple reflections by the wavelength-selective reflective layer. In this way, the energy ratio of the projected light to the light reflected by the projection screen is greatly improved, resulting in improved contrast.

[0074] Figure 19 is a schematic diagram of the structure of a projection screen according to an embodiment of the present invention.

[0075] Taking the projection screen structure shown in Figure 19 as an example, the inclination angle of the inclined surface x1 of the Fresnel structure 121 is 15°, and the connecting surface x2 is provided perpendicular to the plane on which the projection screen is located. Ambient light C with an incident angle of 45° is incident on the outermost diffusion layer 11 of the projection screen, and then its refraction angle becomes 25°. As a result, the incident angle when it is incident on the wavelength-selective reflection layer F becomes 65°. This ambient light is first incident on the wavelength-selective reflection layer on the surface of the connecting surface x2, reflected by the wavelength-selective reflection layer on the surface of the connecting surface x2, and then incident on the wavelength-selective reflection layer on the surface of the reflection surface x1. In other words, this ambient light undergoes two reflections by the wavelength-selective reflection layer, and the incident angles when it is incident on the wavelength-selective reflection layer twice are 65° and 10°, respectively.

[0076] Figure 20 shows the reflectance curve of a light ray incident at an angle of 65° by the wavelength-selective reflective layer according to an embodiment of the present invention, Figure 21 shows the reflectance curve of a light ray incident at an angle of 10° by the wavelength-selective reflective layer according to an embodiment of the present invention, and Figure 22 shows the reflectance curve after two reflections by the wavelength-selective reflective layer according to an embodiment of the present invention.

[0077] As shown in Figures 20 and 21, the wavelengths at which the wavelength-selective reflective layer selectively reflects light rays at incident angles of 65° and 10° are different. By superimposing the two reflectance curves for incident angles of 65° and 10°, the reflectance curve shown in Figure 22 can be obtained. As can be seen from Figure 22, ambient light rays are incident on the wavelength-selective reflective layer at 65° and reflected by the wavelength-selective reflective layer, and then incident on the wavelength-selective reflective layer at 10° and reflected again by the wavelength-selective reflective layer. As a result, the reflectance across the entire visible light band is reduced to some extent. Consequently, when the brightness of ambient light is high, the intensity of ambient light emitted from the projection screen after reflection by the projection screen is significantly reduced.

[0078] Figure 23 shows the relative intensity curve when ambient light rays are incident on the projection screen according to an embodiment of the present invention, and Figure 24 shows the relative intensity curve after reflection of ambient light rays by the projection screen according to an embodiment of the present invention.

[0079] As can be seen by comparing Figures 23 and 24, when ambient light is incident on the projection screen at the incident angle shown in Figure 19, it has high intensity in the visible light band. However, after two reflections by the wavelength-selective reflective layer, the intensity across the entire visible light band decreases to some extent. Since ambient light is light from various directions, it is incident on the projection screen at various different angles. After the diffusion effect of the diffusion layer 11 on the projection screen, the angle at which it is incident on the wavelength-selective reflective layer can be diversified. As a result, the reflectivity across the entire visible light band can be significantly reduced after the incident ambient light undergoes multiple reflections by the wavelength-selective reflective layer. This reduces the reflection of ambient light by the projection screen and improves the contrast of the projected light.

[0080] Embodiments of the present invention further provide several modified structures of projection screens. Figure 25 is a schematic diagram of the structure of a projection screen according to an embodiment of the present invention.

[0081] As shown in Figures 4 and 25, the projection screen further comprises an adhesive layer 14 located between the diffusion layer 11 and the Fresnel structure layer 12 for bonding the diffusion layer 11 and the Fresnel structure layer 12. The adhesive layer 14 can be made of an adhesive material such as epoxy resin, acrylic resin, or silica gel, and is not limited thereto.

[0082] In some embodiments, as shown in Figure 4, the Fresnel structure 121 of the Fresnel structure layer 12 is located on the opposite side of the adhesive layer 14, and the adhesive layer 14 is for bonding the diffusion layer 11 and the surface of the Fresnel structure layer 12 opposite to the Fresnel structure 121 to each other. When the Fresnel structure is provided on the side away from the adhesive layer 14, the semitransparent layer in the wavelength-selective reflection layer F needs to be provided on the side closer to the Fresnel structure 121.

[0083] In some embodiments, as shown in Figure 25, the Fresnel structure 121 of the Fresnel structure layer 12 is located on the side facing the adhesive layer 14, and the adhesive layer 14 is for bonding the diffusion layer 11 and the wavelength-selective reflective layer F in the Fresnel structure 121 to each other. When the Fresnel structure is provided on the side closer to the adhesive layer 14, the semitransparent layer in the wavelength-selective reflective layer F needs to be provided on the side away from the Fresnel structure 121. The arrangement order of each film layer in the wavelength-selective reflective layer F in Figures 4 and 25 is reversed.

[0084] When the Fresnel structure is provided on the side closest to the adhesive layer 14, the adhesive layer 14 protects the wavelength-selective reflective layer F. Since the Fresnel structure layer 12 is located on the side furthest from the viewer and there are no light rays incident on the Fresnel structure layer 12, the specifications for light transmittance and damage resistance to the Fresnel structure layer 12 are reduced, eliminating the need to manufacture the Fresnel structure layer 12 using expensive optical materials. It can then be manufactured using relatively inexpensive industrial materials, thereby reducing production costs.

[0085] Figure 26 is a schematic diagram of the structure of a projection screen according to an embodiment of the present invention.

[0086] In some embodiments, as shown in Figure 26, the diffusion layer 11 includes a second substrate 111 and a diffusion material 112.

[0087] The second substrate 111, which is the substrate for the diffusion material 112, is in contact with the adhesive layer 14, and the diffusion material 112 is located on the surface of the second substrate 111 opposite to the adhesive layer 14.

[0088] Conventional projection systems typically use a laser light source. Because lasers have relatively high collimating properties, the divergence angle of the projected light beam is relatively small, and the collimation of the light beam reflected by the projection screen is high, but the field of view is relatively narrow. By providing a diffusion layer 11, the emission angle of the light beam that passes through the diffusion layer can be diversified. As a result, the light beam that is ultimately emitted from the projection screen has a constant divergence angle, and the field of view from which the viewer observes the projected image is increased. In addition, the diffusion layer 11 eliminates laser speckle and contributes to the optimization of the projected image.

[0089] The diffusion material 112 can be a resin material or inorganic material containing diffusion particles, and the diffusion particles may include, but are not limited to, silica particles, alumina particles, titanium oxide particles, cerium oxide particles, zirconia particles, tantalum oxide particles, zinc oxide particles, magnesium fluoride particles, etc. The diffusion layer 112 can be manufactured by various coating methods, and is not limited thereto.

[0090] The second base material 111 may be, but is not limited to, materials such as PET, polyethylene naphthalate (abbreviated as PEN), polycarbonate (abbreviated as PC), polymethyl methacrylate (abbreviated as PMMA), triacetylcellulose (abbreviated as TAC), cycloolefin polymer (abbreviated as COP), thermoplastic polyurethane (abbreviated as TPU), polyvinyl chloride (abbreviated as PVC), polyimide (abbreviated as PI), polyamide (abbreviated as PA), polyethylene (abbreviated as PE), and polypropylene (abbreviated as PP).

[0091] Figure 27 is a schematic diagram of the structure of a projection screen according to an embodiment of the present invention.

[0092] In some embodiments, as shown in Figure 27, the diffusion layer 11 comprises only a second substrate 111, which is in contact with an adhesive layer 14 and bonded to the Fresnel structure layer 12 via the adhesive layer 14. The material of the second substrate 111 includes a diffusion material, so that when forming the second substrate 111, the first substrate 111 has light diffusion capability and a certain haze. The second substrate 111 containing the diffusion material can widen the viewing angle and reduce light reflection, thereby preventing light from forming a sharp image on the ceiling, providing an anti-reflection effect of ceiling light, and improving the viewer's viewing experience.

[0093] Figure 28 is a schematic diagram of the structure of a projection screen according to an embodiment of the present invention.

[0094] In some embodiments, as shown in Figure 28, the diffusion layer 11 comprises only a second substrate 111, which is in contact with an adhesive layer 14 and bonded to the Fresnel structure layer 12 via the adhesive layer 14. The surface of the second substrate 111 opposite the adhesive layer 14 is an uneven surface. This uneven surface can be formed by sandblasting or alkali treatment of the surface of the second substrate 111, and is not limited thereto. The uneven surface of the second substrate 111 has a certain light diffusion and matting effect, and can therefore exert effects such as expanding the viewing angle, expanding the angle of incidence of incident ambient light, and preventing reflection of ceiling light.

[0095] Figure 29 is a schematic diagram of the structure of a projection screen according to an embodiment of the present invention.

[0096] In some embodiments, as shown in Figure 29, the adhesive layer 14 may contain a light-absorbing material and be colored to improve the black brightness of the projection screen. Specifically, to deepen the color of the adhesive layer 14, the adhesive layer 14 may be colored using pigment materials such as carbon black or dyes, and is not limited thereto.

[0097] Figure 30 is a schematic diagram of the structure of a projection screen according to an embodiment of the present invention.

[0098] In some embodiments, as shown in Figure 30, the projection screen may consist only of a Fresnel structure layer 12 and a diffusion layer 11. The Fresnel structure of the Fresnel structure layer 12 is provided on the side facing the viewer. The diffusion layer 11 is located on the surface of the wavelength-selective reflective layer F opposite to the Fresnel structure layer 12. In this case, the diffusion layer uses a diffusion material 112 that is coated onto the wavelength-selective reflective layer F. The diffusion material 112 can be formed on the surface of the wavelength-selective reflective layer F by methods such as coating or spraying. Using a projection screen structure as shown in Figure 30 allows for an effective reduction in the thickness of the projection screen.

[0099] When a projection screen structure like the one shown in Figure 30 is used, the semi-transparent layer in the wavelength-selective reflective layer F needs to be located on the side away from the Fresnel structure 121. The arrangement order of the film layers in the wavelength-selective reflective layer F in Figures 4 and 30 is reversed.

[0100] In specific implementation, as shown in Figure 30, the Fresnel structure layer 12 may include a third substrate 122 whose surface facing the diffusion layer 11 and the surface opposite the diffusion layer 11 are both flat surfaces, and the Fresnel structure 121 is located on the surface facing the third substrate 122.

[0101] The third substrate 122 can be made of a material such as PET, and is not limited thereto. The Fresnel structure 121 can be manufactured by a UV molding process using a mold having a Fresnel structure and an ultraviolet curing resin. The Fresnel structure 121 can be formed by applying an ultraviolet curing resin to a mold having a Fresnel structure and laminating and UV curing the ultraviolet curing resin using the third substrate 122.

[0102] Figure 31 is a schematic diagram of the structure of a projection screen according to an embodiment of the present invention.

[0103] In some embodiments, as shown in Figure 31, the Fresnel structure layer 12 may be an integral structure, where one surface of the Fresnel structure layer 12 is a Fresnel structure 121, and the surface opposite the Fresnel structure 121 is a flat surface. Using an integral structure for the Fresnel structure layer eliminates the step of joining the substrate and the Fresnel structure, further simplifying the manufacturing process.

[0104] In specific implementation, the integrally molded Fresnel structural layer 12 can be manufactured by thermoforming, and the Fresnel structural layer can be made of a thermoplastic material, but is not limited to that.

[0105] In addition, the projection screen structures shown in Figures 25 to 31 all illustrate the structure of other film layers using examples in which the inclined surface of the Fresnel structure 121 is covered with a wavelength-selective reflective layer F. However, in actual implementation, assuming the same other film layers are present, the inclined surface and connecting surface of the Fresnel structure 121 may be covered with the wavelength-selective reflective layer F.

[0106] Figure 32 is a schematic diagram of the structure of a projection screen in the related technology.

[0107] As shown in Figure 32, in the related technology, the projection screen has a reflective layer 13 manufactured by vapor deposition or sputtering, and the reflective layer 13 manufactured by the conventional process typically covers the entire surface of the Fresnel structure. That is, the light-reflective material layer 13 covers both the inclined surface x1 and the connecting surface x2 of the Fresnel structure.

[0108] As shown in Figure 32, when ambient light C enters the projection screen, it enters not only the inclined surface x1 but also the connecting surface x2. Of these, some of the light rays are reflected by the light-reflecting material layer 13 on the surface of the connecting surface x2 and are ultimately emitted from the projection screen, affecting the contrast of the projected light.

[0109] To improve the contrast of the projected light rays, it is conceivable to avoid some reflection of ambient light at the connection surfaces by removing the light-reflecting material layer 13 on the surface of the connection surfaces x2.

[0110] Figure 33 is a schematic diagram of the structure of a projection screen in related technology.

[0111] As shown in Figure 33, if the light-reflecting material layer 13 is not provided on the surface of the connection surface x2, the ambient light C that would normally be reflected multiple times through the light-reflecting material layer 13 on the surface of the connection surface x2 can be emitted directly from the connection surface x2. In this way, the ambient light in this part that would normally be reflected towards the viewer no longer interferes with the projected light L, and the contrast of the projected light can be improved to some extent.

[0112] However, the light-reflecting material layer on the surface of a Fresnel structure is usually manufactured using a film deposition process. When attempting to deposit a film on only a portion of the surface of a Fresnel structure, it is usually necessary to modify the deposition equipment, which presents challenges in terms of the difficulty and cost of adjusting the equipment.

[0113] In view of the above, the embodiment of the present invention provides a method for manufacturing a projection screen that does not depend on a film deposition apparatus and, by adjusting the film deposition conditions and the amount of film deposited, can achieve the objective of depositing a film only on the connecting surface of the Fresnel structure and minimizing the amount of film deposited on the connecting surface.

[0114] Figure 34 is a flowchart of a method for manufacturing a projection screen according to an embodiment of the present invention.

[0115] As shown in Figure 34, the method for manufacturing a projection screen includes S10 for manufacturing a Fresnel structure layer, S20 for forming a discontinuous first thin film on the inclined surface of the Fresnel structure and forming a continuous second film layer on the first thin film, and S30 for forming a surface functional layer on one side of the Fresnel structure with a reflective layer.

[0116] In embodiments of the present invention, the reflective layer may be formed using a single reflective material, or the reflective layer may be a wavelength-selective reflective layer, but is not limited thereto. Vapor deposition or sputtering methods are still used to form the reflective layer on the Fresnel structure layer, but by adjusting the deposition conditions and deposition amount, it is possible to form a light-reflecting layer on the inclined surface of the Fresnel structure while simultaneously minimizing the deposition amount on the connection surface.

[0117] Specifically, the Fresnel structure layer can be manufactured by multiple methods. Figure 35 is a schematic diagram 1 of the manufacturing flow of the Fresnel structure layer according to an embodiment of the present invention, and Figure 36 is a schematic diagram 2 of the manufacturing flow of the Fresnel structure layer according to an embodiment of the present invention.

[0118] In some embodiments, the Fresnel structure 121 can be formed by applying an ultraviolet-curable resin to a mold M having a Fresnel structure, and then laminating and UV-curing the ultraviolet-curable resin using a substrate. As shown in Figure 35, first, an ultraviolet-curable resin f' is applied to a mold M having a Fresnel structure on its surface to provide a third substrate 122. The ultraviolet resin f' on the mold M is then laminated to the third substrate 122 under a predetermined pressure, and UV irradiation is performed from the side of the third substrate 122 to cure the ultraviolet-curable resin f'. As the ultraviolet-curable resin f' hardens, it adheres closely to the third substrate 122, transferring the Fresnel shape of the mold M to the third substrate 122, thereby forming the Fresnel structure 121 on the surface of the third substrate 122.

[0119] Fresnel structure layers formed using UV-curing resins typically have a separate structure from the substrate. On the other hand, Fresnel structure layers manufactured by thermoforming have an integrated structure, eliminating the need for the step of joining the substrate and the Fresnel structure. As shown in Figure 36, a thermoplastic material such as TPU or PVC can be used for an integrally molded Fresnel structure layer. First, a third substrate 122 having thermoplastic properties is provided, and a Fresnel structure layer having a Fresnel structure 121 can be formed by thermoforming the third substrate 122 using a mold M having a heated Fresnel structure.

[0120] As shown in Figures 35 and 36, the surface of the manufactured Fresnel structure layer has multiple Fresnel structures 121, and depending on different application scenes and manufacturing processes, each Fresnel structure 121 may form a concentric circular structure that is sequentially expanded and arranged along the radial direction, or each Fresnel structure 121 may be a linear structure that extends along the horizontal direction of the projection screen and is arranged vertically in the horizontal direction, but is not limited thereto.

[0121] In the embodiment of the present invention, when manufacturing a reflective layer, adjustments are made to both the film deposition conditions and the amount of film deposited so that a reflective layer is formed only on the inclined surface x1 of the Fresnel structure and not on the connecting surface x2.

[0122] Specifically, in the embodiment of the present invention, multiple interruption periods are inserted during the film deposition process so that film deposition time periods and interruption periods are performed alternately.

[0123] Figure 37 shows the curve of the film thickness in related technologies, and Figure 38 shows the curve of the film thickness according to an embodiment of the present invention.

[0124] As shown in Figure 37, in the related technology, the film formation process is continuous, and ultimately a continuous light-reflective film is formed on both the inclined surface x1 and the connecting surface x2 of the Fresnel structure.

[0125] On the other hand, in the embodiment of the present invention, as shown in Figure 38, by inserting multiple interruption periods k2 during the film deposition process, the film deposition period k1 and the interruption period k2 are alternated throughout the entire film deposition process. By controlling the duration of the film deposition period k1 and the interruption period k2, as well as the amount of film deposited, it is possible to first form a discontinuous first thin film on the inclined surface x1 of the Fresnel structure, and then form a continuous second film layer on the first thin film. In this way, it is possible to form a continuous light-reflecting material film only on the inclined surface x1 of the Fresnel structure and minimize the amount of film deposited on the connecting surface x2.

[0126] Figures 39 to 42 are schematic diagrams of the structure of the reflective layer during the film formation process according to an embodiment of the present invention.

[0127] Specifically, in the film deposition process, the transition from no film to a continuous film involves "nucleation → nucleation → island → island coalescence → continuous film," where the state up to island coalescence is called a discontinuous film. Furthermore, the above morphology of the film is usually related to the film thickness, which largely depends on the deposition time, and the deposition time is related to the deposition rate.

[0128] Based on the above principle, an embodiment of the present invention involves inserting an interruption period during the film deposition process and adjusting the film deposition time and deposition rate to first form a discontinuous first thin film on the inclined surface x1 of the Fresnel structure.

[0129] As shown in Figure 39, sharp step portions t are formed at the boundaries between the inclined surface x1 and the connecting surface x2 of each Fresnel structure. When the amount of film deposited is small, the surrounding incident atoms are suppressed, and many atoms x1 are incident on the inclined surface x1, while on the connecting surface x2, atoms x1 are incident only on local regions close to the step portions.

[0130] As shown in Figure 40, after the film deposition period ends, film deposition is interrupted for a certain period of time, during which the incident atoms become stable nuclei b, and the presence of the step portion t suppresses the wrapping of atoms around the connecting surface x2, thereby causing the inclined surface x1 to form preferentially over the discontinuous first thin film s1.

[0131] As shown in Figure 41, after the interruption period ends, film deposition continues on the Fresnel structure. At this time, incident atoms a2 are deposited around the previously formed nuclei, and the area around the location with the first thin film s1 becomes higher, so film deposition proceeds preferentially to other locations.

[0132] As shown in Figure 42, after multiple deposition time periods are accumulated, the thin film continues to grow, and there are no longer any atomic nuclei preferentially forming on the inclined surface x1, resulting in a continuous second film layer s2 that extends across the entire inclined surface.

[0133] When implementing this method, the interruption period k2 should be longer than the film deposition period k1, and the longer the interruption period k2, the better the effect. Considering the feasibility of actual operation, the length of the interruption period k2 can be 30s to 60s, and the length of the film deposition period can be 1s to 10s (for example, about 5s).

[0134] In this way, a reflective layer can be formed on the inclined surface of each Fresnel structure in the Fresnel structure layer, and after obtaining a Fresnel structure layer having a light-reflecting layer on its surface, a surface functional layer can be formed on the opposite surface of the Fresnel structure layer.

[0135] The surface functional layer is typically located on the outermost surface of the projection screen. In embodiments of the present invention, the surface functional layer can be subjected to different treatments as needed to achieve effects such as expanding the viewing angle, preventing reflection of ambient light, and preventing reflection of ceiling light. The method for manufacturing the surface functional layer may include bonding, spraying, etching, etc., and is selected according to the type of surface functional layer, and is not limited thereto.

[0136] In some embodiments, the wavelength-selective reflective layer F in the above embodiment can be used as the reflective layer, and the diffusion layer 11 in the above embodiment can be used as the surface functional layer.

[0137] When a wavelength-selective reflective layer F is used as the reflective layer, the wavelength-selective reflective layer comprises a stacked semi-transparent layer 131, a light-transmitting medium layer 133, and a reflective layer 132. In order to form the wavelength-selective reflective layer only on the inclined surface x1 of the Fresnel structure, any of the film layers of the wavelength-selective reflective layer (semi-transparent layer 131, light-transmitting medium layer 133, and reflective layer 132) can be manufactured by the discontinuous film deposition process described above. The film layer manufactured by the discontinuous film deposition process first forms a discontinuous first thin film, and then forms a continuous second film layer on the first thin film. The first thin film and the second film layer can be manufactured from the same material or different materials as needed. When the first thin film and the second film layer are manufactured from the same material, the final film layer does not have a clear boundary, and a continuous film layer is formed only on the inclined surface of the Fresnel structure.

[0138] For example, when the reflective layer 132 in the wavelength-selective reflective layer is manufactured by the discontinuous film deposition process described above, the discontinuous thin film is generally 1 nm to 10 nm in thickness, so the thickness of the first thin film s1 formed by the reflective layer 132 is 1 nm to 10 nm. The second film layer needs to have good light reflectivity, and in the embodiments of the present invention, the thickness of the second film layer s2 in the reflective layer 132 is 50 nm to 200 nm. Typically, the thickness of the second film layer s2 is kept below 500 nm to avoid the reflective film becoming excessively thick.

[0139] The purpose of forming the first thin film s1 first is to ensure that the subsequent film grows preferentially on the inclined surface. Furthermore, since the first thin film s1 is a relatively thin, discontinuous film and does not have reflectivity, it can be manufactured using a metallic material or a transparent dielectric material. The metallic material can be Ag or Al, and the transparent dielectric material can be Al2O3, Nb2O5, TiO2, ITO, SiO2, etc., and is not limited thereto.

[0140] The second film layer s2 on the first thin film s1 is for reflecting projected light rays and can therefore be manufactured using a reflective metallic material, such as Ag or Al, but is not limited thereto.

[0141] Similarly, the semi-transparent layer 131 and the transparent medium layer 133 in the wavelength-selective reflective layer F can also be manufactured using the discontinuous deposition process described above, allowing for deposition only on the inclined surface x1 of the Fresnel structure and minimizing the amount of film deposited on the connecting surface x2.

[0142] In particular, since the light-transmitting medium layer in the wavelength-selective reflective layer F uses a light-transmitting material, when formed on the inclined surface x1 and connecting surface x2 of the Fresnel structure, it exhibits only light transmittance. These light-transmitting film layers do not interfere with light even when formed on the connecting surface x2, and therefore, these completely light-transmitting film layers can also be manufactured using conventional film deposition processes, and are not limited to such processes. Typically, to reduce material costs, discontinuous film deposition processes are used during implementation.

[0143] Furthermore, in a particular embodiment, a semi-transparent layer 131 is first formed on the Fresnel structure, and then a light-transmitting medium layer 133 and a reflective layer 132 are sequentially formed on the semi-transparent layer 131. The semi-transparent layer 131 can be created by applying a discontinuous film deposition process, and then the light-transmitting medium layer 133 and the reflective layer 132 can be created by sequentially applying a discontinuous film deposition process. However, since the semi-transparent layer 131 transmits most of the light beam and reflects only a small portion of the light beam, the semi-transparent layer 131 can also be created by applying a conventional overall film deposition process, and then the light-transmitting medium layer 133 and the reflective layer 132 can be created by sequentially applying a discontinuous film deposition process.

[0144] Even in structures where the reflective layer is made solely of light-reflective material, the reflective layer can be manufactured using a discontinuous film deposition process. Specifically, a first thin film s1 of 1 nm to 10 nm can be formed on the inclined surface x1 of the Fresnel structure, and then a second film layer s2 of 50 nm to 200 nm can be formed on the first thin film s1.

[0145] Based on the same inventive concept, embodiments of the present invention further provide projection screens manufactured by any of the above manufacturing methods. Figure 43 is a schematic diagram of the structure of a projection screen according to an embodiment of the present invention.

[0146] As shown in Figure 43, the projection screen comprises a surface functional layer 11', a Fresnel structure layer 12, and a reflective layer 13'.

[0147] The surface functional layer 11' is located on the outermost surface side of the projection screen. In embodiments of the present invention, the surface functional layer 11' is located on the side closest to the viewer and acts to protect the projection screen. In addition, the surface functional layer 11' can be treated by various means as needed to achieve effects such as expanding the viewing angle, preventing reflection of ambient light, and preventing reflection of ceiling light. In some embodiments, the surface functional layer 11' can be the same as the diffusion layer 11.

[0148] The Fresnel structure layer 12 is located on one side of the surface functional layer 11', specifically on the side opposite the viewer of the surface functional layer 11'. The surface on the Fresnel structure layer 12 side is provided with Fresnel structures 121 distributed according to a predetermined rule, and the Fresnel structures 121 have an inclined surface x1 and a connecting surface x2 to which they are connected to each other.

[0149] The reflective layer 13' is located on the inclined surface x1 of each Fresnel structure 121. The reflective layer 13' according to the embodiment of the present invention is manufactured by a film deposition process such as vapor deposition or sputtering, and the equipment used is an advanced vapor deposition or sputtering equipment in the related technology. There is no need to modify the film deposition equipment, and by adjusting the deposition conditions and deposition amount and using a discontinuous film deposition process, the reflective layer can be formed on the inclined surface of the Fresnel structure, and the amount of film deposited on the connecting surface can be minimized, thereby avoiding the problems of high difficulty and cost in adjusting the equipment.

[0150] In some embodiments, the reflective layer 13' is a light-reflective material layer 13 in the related technology.

[0151] In some embodiments, the reflective layer 13' can be the wavelength-selective reflective layer F according to the above embodiment.

[0152] Furthermore, any of the film layers of the reflective layer 13' can be manufactured using a discontinuous thin-film process. During the manufacturing process, a discontinuous first thin film s1 located on the inclined surface of the Fresnel structure and a second film layer s2 located on the first thin film s1 are formed.

[0153] In the projection screen according to the embodiment of the present invention, since the reflective layer is provided only on the inclined surface of the Fresnel structure, ambient light incident on the connection surface can be emitted directly from the connection surface. In this way, the ambient light in this part, which would normally be reflected towards the viewer, does not interfere with the projected light rays, and thus the contrast of the projected light rays can be improved to some extent.

[0154] Figure 44 is a schematic diagram of the structure of a projection screen according to an embodiment of the present invention.

[0155] As shown in Figure 44, a light-absorbing layer 15 may be provided on the opposite side of the surface functional layer 11' of the Fresnel structure layer 12. The light-absorbing layer can absorb light rays emitted from the connection surface x2 of the Fresnel structure, preventing these light rays from being re-incident to the projection screen due to reflection or other effects. The light-absorbing layer 15 can be realized by doping a film layer with a light-absorbing material. For example, the film layer material can be colored by including carbon black or dyes in order to absorb light rays, but this is not limited to the material used.

[0156] The projection screen according to the embodiment of the present invention further comprises an adhesive layer, and the arrangement position of the adhesive layer and the modified structure of the projection screen can be described by referring to the above embodiment, so a detailed explanation is omitted here.

[0157] An embodiment of the invention further provides a projection system, which is shown in Figure 1. The projection system comprises a projection device 2 and a projection screen 1.

[0158] Figure 45 is a schematic diagram of the structure of a projection device according to an embodiment of the present invention.

[0159] As shown in Figure 45, the projection device comprises a light source device 21, an illumination light path 22, a light modulation member 23, and a projection lens 24. Here, the illumination light path 22 is located on the light-emitting side of the light source device 21, the light modulation member 23 is located on the light-emitting side of the illumination light path 22, and the projection lens 24 is located on the light-emitting side of the light modulation member 23.

[0160] The light source device 21 can be a laser light source device. The laser light source device may be a monochromatic laser device, a laser device capable of emitting laser light of multiple colors, or multiple laser devices emitting laser light of different colors. When a monochromatic laser device is used as the laser light source device, it is necessary to further provide a color wheel for color conversion in the laser display device, and the monochromatic laser device can achieve the objective of emitting primary color light of different colors in a time series in accordance with the color wheel. When a laser device capable of emitting laser light of multiple colors is used as the laser light source device, it is necessary to control the laser light source so that it emits laser light of different colors in a time series to produce primary color light.

[0161] In embodiments of the present invention, a three-color laser light source device can be used as the light source device. This three-color laser light source device may be a laser device that emits three primary color laser light, such as an MCL laser device, or it may include a red laser device, a green laser device, and a blue laser device, each emitting three primary color laser light. By using a three-color laser light source device, it is possible to improve the color gamut of the projected image, have better color expression capabilities, and accurately reproduce the input image.

[0162] The illumination light path 22, located on the light-emitting side of the light source device 21, collimates the light emitted from the light source device 21 while simultaneously allowing the light emitted from the light source device 21 to be incident on the light modulation member 23 at an appropriate angle. The illumination light path 22 may include multiple lenses or lens groups, but is not limited thereto.

[0163] The optical modulation member 23 is for modulating the incident light ray. In specific implementations, the optical modulation member 23 can be a Digital Micromirror Device (DMD). When the light beam passes through the illumination path 22, it will meet the illumination size and incident angle required by the DMD. The surface of the DMD is equipped with multiple micro-reflective mirrors, each of which can be driven and deflected independently, and the brightness of the light ray incident on the projection lens 24 is controlled by controlling the deflection angle of the DMD.

[0164] The projection lens 24 is used to form an image of the light emitted from the light modulation member 23, and after image formation by the projection lens 24, the image is projected.

[0165] In the embodiment of the present invention, the projection device 2 can be an ultra-short-throw projection device; that is, the projection lens 24 in the projection device is an ultra-short-throw projection lens. By using an ultra-short-throw projection device, the distance between the projection device 2 and the projection screen 1 can be significantly reduced, thereby shortening the projection distance and enabling the display of large-screen images.

[0166] The projection screen 1 is located on the light-emitting side of the projection lens in the projection device. The projection screen 1 comprises a surface functional layer, a Fresnel structure layer, and a wavelength-selective reflective layer located on the surface of at least a portion of the Fresnel structure in the Fresnel structure layer. The wavelength-selective reflective layer selectively reflects projected light rays from the projection device while significantly reducing the reflectivity to light rays in other wavelength bands, enabling a black appearance when the projection device is turned off and a bright display when the projection device is turned on, thereby significantly improving the contrast of the projected image.

[0167] Although preferred embodiments of the present invention have already been described, those skilled in the art, having grasped the basic creative concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to describe both the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0168] Clearly, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the invention. Thus, if these amendments and modifications of the present invention fall within the scope of the claims of the present invention and the equivalent art, the present invention is also intended to include these changes and modifications. [Explanation of symbols]

[0169] 1. Projection screen 2-Projection device 10-Surface layer 11-Diffusion layer 11'-Surface functional layer 111-Second substrate 112-Diffusion materials 12-Fresnel structural layer 121-Fresnel structure x1-slope x2 - Connection side 122-Third Substrate 13-Light reflective material layer 13'-reflective layer 14-adhesive layer F-wavelength selective reflective layer 131-Semi-transparent layer 132-Reflective layer 133-Transparent medium layer 134-First substrate 21-Light source device 22-Illumination light path 23-Optical Modulation Member 24-Projection Lens s1 - First thin film s2 - Second film layer f'-UV curing resin M-Mold C-Environmental rays L-projection ray

Claims

1. It is a projection screen, Diffusion layer and A Fresnel structure layer located on one side of the diffusion layer and having a plurality of Fresnel structures sequentially arranged on the surface of that side, The Fresnel structure layer comprises a wavelength-selective reflective layer covering at least a portion of the surface of the Fresnel structure, wherein the reflectivity of the projected light emitted from the projection device is higher than the reflectivity of the light in other wavelength bands. The projected light beam includes a red laser, a green laser, and a blue laser, wherein the wavelength range selected corresponding to the central wavelength of the red laser is 635 nm to 650 nm, the wavelength range selected corresponding to the central wavelength of the green laser is 520 nm to 532 nm, and the wavelength range selected corresponding to the central wavelength of the blue laser is 445 nm to 465 nm. The wavelength-selective reflection layer is A semi-transparent layer located on the side closer to the aforementioned diffusion layer, The semi-transparent layer, a reflective layer located on the opposite side of the diffusing layer, A light-transmitting medium layer is located between the semi-transparent layer and the reflective layer, The product of the refractive index and thickness of the light-transmitting medium layer satisfies the conditions for causing the light rays emitted from the projection device to resonate. The semi-transparent layer uses a laminated structure made of at least one of the following metals: aluminum, niobium, silver, and titanium. A projection screen having a semi-transparent layer thickness of 2 nm to 20 nm.

2. The Fresnel structure comprises inclined surfaces connected to each other and connecting surfaces, The inclined surface is provided so as to be inclined with respect to the plane on which the diffusion layer is located, and the inclination angle of the inclined surface satisfies the requirement that the projected light rays of the wavelength-selective reflective layer incident on the surface of the inclined surface be reflected in the direction of the viewer. The projection screen according to claim 1, wherein the wavelength-selective reflective layer is coated on the surface of the inclined surface of the Fresnel structure.

3. The material of the reflective layer is aluminum, aluminum alloy, silver, or silver alloy. The projection screen according to claim 1, wherein the thickness of the reflective layer is greater than 50 nm and less than 100 nm.

4. The projection screen according to claim 1, wherein the material of the light-transmitting medium layer is a metal oxide, a nitride, or a transparent resin.

5. The material of the light-transmitting medium layer is TiO ２ , Nb ２ O ５ , ZrO ２ Al ２ O ３ , ZnO ２ and SiO ２ The projection screen according to claim 4, wherein at least one of the following is used.

6. The projection screen according to claim 4, wherein the product of the thickness of the light-transmitting medium layer and the refractive index is 1200 to 1400 nm, and the wavelength-selective reflective layer simultaneously reflects a red laser, a green laser, and a blue laser emitted from the projection device.

7. The projection screen according to claim 1, wherein the central wavelength of the red laser reflected by the wavelength-selective reflective layer is 635 nm, 650 nm, or 643 nm; the central wavelength of the green laser reflected by the wavelength-selective reflective layer is 520 nm, 525 nm, or 532 nm; and the central wavelength of the blue laser reflected by the wavelength-selective reflective layer is 445 nm or 465 nm.

8. The projection screen according to claim 1, wherein the wavelength-selective reflective layer further comprises a first substrate located on the opposite side of the semitransparent layer from the light-transmitting medium layer.

9. The system further comprises an adhesive layer located between the diffusion layer and the Fresnel structure layer, The inclination angle of the Fresnel structure in the Fresnel structure layer is located on the opposite side of the adhesive layer, and the adhesive layer is configured to bond the diffusion layer and the surface of the Fresnel structure layer opposite to the inclination angle of the Fresnel structure to each other. Alternatively, the inclination angle of the Fresnel structure in the Fresnel structure layer faces the inclination angle of the adhesive layer, and the adhesive layer is configured to bond the diffusion layer and the wavelength-selective reflection layer in the Fresnel structure to each other. The projection screen according to claim 2, wherein the adhesive layer includes a light-absorbing material.

10. The Fresnel structure layer has an inclination angle that faces the viewer, and the diffusion layer is located on the surface of the wavelength-selective reflection layer opposite to the Fresnel structure layer. The projection screen according to claim 1, wherein the diffusion layer is a coating layer of a diffusion material that covers the wavelength-selective reflection layer.

11. The Fresnel structure layer comprises a third substrate having a flat surface on the side facing the diffusion layer and on the side opposite the diffusion layer, and the Fresnel structure is located on the surface of the third substrate. Alternatively, the projection screen according to claim 1, wherein the Fresnel structure layer is an integral structure, one surface of the Fresnel structure layer is a Fresnel structure, and the surface of the Fresnel structure layer opposite the Fresnel structure is a flat surface.

12. The projection screen according to claim 2, further comprising a light-absorbing layer located on the opposite side of the diffusion layer of the Fresnel structure layer, wherein the light-absorbing layer is configured to absorb ambient light emitted from the connecting surface of the Fresnel structure.

13. The projection screen according to claim 12, wherein the light-absorbing layer is a film layer doped with a light-absorbing material.

14. A method for manufacturing a projection screen, A manufacturing process for a Fresnel structure, comprising: manufacturing a Fresnel structure layer, having a plurality of Fresnel structures in the Fresnel structure layer, wherein the Fresnel structures have inclined surfaces and connecting surfaces that connect to each other; A manufacturing process for a reflective layer, comprising forming a discontinuous first thin film on the inclined surface of the Fresnel structure and forming a continuous second film layer on the first thin film, A method for manufacturing a projection screen, comprising the step of manufacturing a surface functional layer, in which a surface functional layer is formed on one side surface of the Fresnel structural layer having the reflective layer.

15. The manufacturing process for the reflective layer uses a vapor deposition or sputtering process. The manufacturing process for the reflective layer is as follows: This includes inserting multiple interruption periods during the film deposition process, such that film deposition time and interruption periods are performed alternately. The method for manufacturing a projection screen according to claim 14, wherein the duration of the interruption period is longer than the duration of the film formation period, the duration of the interruption period is 30s to 60s, and the duration of the film formation period is 1s to 10s.

16. The aforementioned reflective layer is a wavelength-selective reflective layer, The wavelength-selective reflection layer is A semi-transparent layer located on the side closer to the surface functional layer, The semi-transparent layer comprises a reflective layer located on the opposite side of the surface functional layer, A light-transmitting medium layer is located between the semi-transparent layer and the reflective layer, The product of the refractive index and thickness of the light-transmitting medium layer satisfies the conditions for causing resonance of the projected light ray from the projection device. The method for manufacturing a projection screen according to claim 14, wherein one of the film layers in the wavelength-selective reflective layer forms a discontinuous first film layer and a continuous second film layer is formed thereon.

17. The first thin film in the reflective layer is made of a metallic material or a transparent dielectric material, and the second film layer in the reflective layer is made of a metallic material. The method for manufacturing a projection screen according to claim 16, wherein the thickness of the first thin film is 1 nm to 10 nm, and the thickness of the second film layer is 50 nm to 200 nm.

18. It is a projection system, The present invention comprises a projection device for emitting projected light rays, and a projection screen according to claim 1 located on the light-emitting side of the projection device, The projection device is an ultra-short-throw laser projection device, and the projection device is A three-color laser light source device for emitting three primary color laser light, A light modulation member located on the light-emitting side of the three-color laser light source device for modulating the three primary color laser light emitted from the three-color laser light source device, A projection system comprising: a projection lens located on the light-emitting side of the light modulation member.

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