Projection screen and manufacturing method therefor, and projection system

Abstract

Disclosed in the present application are a projection screen and a manufacturing method therefor, and a projection system. The projection screen comprises a polarizing layer, a Fresnel lens layer, and a reflective structure layer located on the surfaces of lens units of the Fresnel lens layer, wherein the reflective structure layer comprises a resonance layer, which can perform resonance enhancement on incident projection light and absorb light of other wavelengths, thereby improving the contrast of the projection light. The optical thickness of a resonance layer is not uniform at different positions of a projection screen; at positions of a polarizing layer where the white gain is relatively low, the optical thickness of the resonance layer is set to correspond to a relatively high white gain value; and at positions of the polarizing layer where the white gain is relatively high, the optical thickness of the resonance layer is set to correspond to a relatively low white gain value. Thus, by means of changing the optical thickness of the resonance layer, the decrease in gain uniformity caused by the difference in the transmittance of the polarizing layer for projection light is compensated for, such that the gain values at different positions of the projection screen are more consistent, thereby improving the gain uniformity of the projection screen.

Description

Projection screen, manufacturing method thereof and projection system

[0001] Cross-reference to related applications

[0002] This application claims priority to the Chinese patent application No. 202411365321.1, filed on September 27, 2024, entitled “A projection screen, manufacturing method thereof and projection system”, the entire content of which is incorporated herein by reference. TECHNICAL FIELD

[0003] The present application relates to the field of projection technology, in particular to a projection screen, a manufacturing method thereof and a projection system. BACKGROUND

[0004] With the development of display products towards large size, considering the power consumption, weight and size, projection display products as a substitute for liquid crystal television, organic electroluminescent television large screen products market rapidly expanded. Laser television using ultra-short focus projection equipment because of high image quality and the convenience of large screen has been rapidly developed.

[0005] The current projection system can usually be used with a projection screen. Projection light emitted by a projection device is incident on the projection screen, and the projection light is reflected by the projection screen to the human eye to watch the projection image. The laser projection device usually emits polarized light. In order to improve the contrast of the projection light, a polarizing plate can be arranged inside the projection screen. However, due to the non-uniform transmittance of the polarizing plate to the projection light, the gain uniformity of the projection screen is poor. SUMMARY

[0006] The present application provides a projection screen, comprising:

[0007] A polarizing layer, the transmission axis of the polarizing layer is perpendicular to the horizontal direction; the projection light emitted by the projection device to the projection screen is linearly polarized light;

[0008] A Fresnel lens layer located on the side of the polarizing layer away from the viewer; the Fresnel lens layer comprises:

[0009] A plurality of lens units, the plurality of lens units are arranged in a concentric and expanding circular arc shape; each lens unit comprises a lens surface and a non-lens surface, the lens surface is at a set angle relative to the plane on which the projection screen is located; and

[0010] a reflective structure layer, covering at least the lens surface of each lens unit of the Fresnel lens layer; the reflective structure layer has a reflectivity greater than that of other wavelengths of light for the projection light emitted by the projection device; the reflective structure layer comprises:

[0011] a resonance layer, configured to resonate and enhance the projection light emitted by the projection device and absorb other wavelengths of light; the optical thickness of the resonance layer is unevenly distributed in the plane of the projection screen; the optical thickness of the resonance layer is the thickness of the resonance layer perpendicular to the lens surface.

[0012] The embodiments of the present application also provide a projection system, comprising:

[0013] a projection device, configured to emit projection light; the projection light is linearly polarized light; and

[0014] a projection screen, located on the light emitting side of the projection device; the projection screen is the projection screen described above.

[0015] the projection device emits the projection light obliquely to the projection screen;

[0016] The projection device is an ultra-short focus laser projection device; the projection device comprises:

[0017] a three-color laser light source device, configured to emit three primary color lasers;

[0018] a display element, located on the light emitting side of the three-color laser light source device, configured to modulate the incident light to form an image beam for image display; and

[0019] a lens, located on the light emitting side of the display element.

[0020] The embodiments of the present application also provide a manufacturing method of a projection screen, comprising:

[0021] a Fresnel lens layer manufacturing process; the Fresnel lens layer comprises a plurality of lens units, and the plurality of lens units are arranged in a concentric and expanding circular arc shape; each lens unit comprises a lens surface and a non-lens surface;

[0022] a reflective structure layer manufacturing process: a reflective structure layer is manufactured on each lens unit of the Fresnel lens layer; the reflective structure layer comprises a resonance layer;

[0023] a bonding process: a polarizing layer is bonded with the Fresnel lens layer with the reflective structure layer;

[0024] The optical thickness of the resonance layer is unevenly distributed in the plane where the projection screen is located, so as to compensate for the difference in the transmittance of the polarizing layer to the projection light. BRIEF DESCRIPTION OF DRAWINGS

[0025] Fig. 1 is a structural schematic diagram of a projection system provided by an embodiment of the present application;

[0026] Fig. 2 is a schematic diagram of a cross-sectional structure of a projection screen provided by an embodiment of the present application;

[0027] Fig. 3 is a schematic diagram of a planar structure of a Fresnel lens layer provided by an embodiment of the present application;

[0028] Fig. 4 is a schematic diagram of a cross-sectional structure of a projection screen provided by an embodiment of the present application;

[0029] Fig. 5 is a schematic diagram of a cross-sectional structure of a reflective structure layer provided by an embodiment of the present application;

[0030] Fig. 6 is a reflectivity curve of the reflective structure layer to light of different wavelengths provided by an embodiment of the present application;

[0031] Fig. 7 is a schematic diagram of a polarizing principle of a polarizing layer provided by an embodiment of the present application;

[0032] Fig. 8 is a schematic diagram of a planar structure of a projection screen provided by an embodiment of the present application;

[0033] Fig. 9 is a diagram of an included angle distribution between the polarization direction of the projection light and the transmission axis of the polarizing layer provided by an embodiment of the present application;

[0034] Fig. 10 is a white gain distribution diagram of a polarizing layer provided by an embodiment of the present application;

[0035] Fig. 11 is a schematic diagram of the relationship between the physical thickness and the optical thickness provided by an embodiment of the present application;

[0036] Fig. 12 is a diagram of the tilt angle distribution of the lens surface of a lens unit provided by an embodiment of the present application;

[0037] Fig. 13 is a diagram of the optical thickness distribution of a resonance layer provided by an embodiment of the present application;

[0038] Fig. 14 is a reflectivity curve of the reflective structure layer to light of different wavelengths provided by an embodiment of the present application;

[0039] Fig. 15 is a diagram of the relationship between the optical thickness and the white gain of a resonance layer provided by an embodiment of the present application;

[0040] Fig. 16 is a diagram of the optical thickness distribution of a resonance layer provided by an embodiment of the present application;

[0041] FIG. 17 is a schematic view of a first area of the resonance layer according to an embodiment of the present application;

[0042] FIG. 18 is a white gain distribution diagram of the reflective structure layer according to an embodiment of the present application;

[0043] FIG. 19 is a white gain distribution diagram of the projection screen according to an embodiment of the present application;

[0044] FIG. 20 is a schematic view of a cross-sectional structure of the projection screen according to an embodiment of the present application;

[0045] FIG. 21 is a schematic view of a structure of the diffusion layer according to an embodiment of the present application;

[0046] FIG. 22 is a schematic view of a structure of the diffusion layer according to an embodiment of the present application;

[0047] FIG. 23 is a schematic view of a cross-sectional structure of the projection screen according to an embodiment of the present application;

[0048] FIG. 24 is a flowchart of a manufacturing method of the projection screen according to an embodiment of the present application;

[0049] FIG. 25 is a schematic view of a manufacturing process of the resonance layer according to an embodiment of the present application;

[0050] FIG. 26 is a schematic view of an opening shape of the mask plate according to an embodiment of the present application;

[0051] FIG. 27 is a curve of the opening rate of the mask plate according to an embodiment of the present application;

[0052] FIG. 28 is a curve of the opening rate of the mask plate according to an embodiment of the present application;

[0053] FIG. 29 is a schematic view of a manufacturing process of the resonance layer according to an embodiment of the present application;

[0054] FIG. 30 is a schematic view of an opening shape of the mask plate according to an embodiment of the present application;

[0055] FIG. 31 is a schematic view of an opening shape of the mask plate according to an embodiment of the present application;

[0056] FIG. 32 is a schematic view of a structure of the projection device according to an embodiment of the present application. DETAILED DESCRIPTION

[0057] In order to make the above objectives, features and advantages of the present application more apparent, comprehensible and easier to understand, the present application will be further described below with reference to the accompanying drawings and examples. However, the example embodiments can be implemented in various forms, and should not be construed as being limited to the embodiments set forth herein; on the contrary, these embodiments are provided so that the present application is more complete and comprehensive, and the concept of the example embodiments is fully conveyed to those skilled in the art. The same reference numerals in the drawings represent the same or similar structures, and thus repeated description thereof will be omitted. The expressions of position and direction described in the present application are described with reference to the drawings, but can be changed as needed, and the changes made are included in the scope of protection of the present application. The drawings of the present application are only used to illustrate the relative positional relationship and do not represent the true proportions.

[0058] With the popularization of laser display products, as large-screen products to replace liquid crystal (LCD) televisions and organic light-emitting diode (OLED) televisions, the market for laser televisions has rapidly expanded. In order to achieve better brightness and display effect, projection equipment is generally used with a projection screen.

[0059] As shown in FIG. 1, the projection system includes a projection device 2 and a projection screen 1.

[0060] The projection screen 1 is located on the light exit side of the projection device 2, and the audience faces the projection screen 1. The projection device 2 emits projection light, the projection light is incident on the projection screen 1, and the projection light is emitted in the direction of the audience through the projection screen 1, so that the audience can watch the projected image.

[0061] When the projection device 2 and the audience are located on the same side of the projection screen 1, the projection system is referred to as a front projection system, and when the projection device 2 and the audience are located on the two sides of the projection screen 1, respectively, the projection system is referred to as a rear projection system. The front projection system is that the projection device 2 emits projection light to the projection screen 1, and the projection screen 1 reflects the projection light to the audience, so that the audience can watch the projected image. The rear projection system is that the projection device 2 emits projection light to the projection screen 1, and the projection light is emitted to the audience through the projection screen 1, so that the audience can watch the projected image.

[0062] The embodiment of the present application takes a front projection type ultra-short focus projection system as an example to specifically describe the structure of the projection screen. The projection screen 1 can be installed on a wall or hung at a high place, and can also be integrated with the projection device to form a display device. In the use state, the projection device 2 can be located below the projection screen 1, and emits projection light to the projection screen 1 from the oblique upper side of the projection screen 1; or the projection device 2 can be located above the projection screen 1, and emits projection light to the projection screen 1 from the oblique lower side of the projection screen 1. Since the ultra-short focus projection system has a small projection ratio, a larger size of the projection image can be obtained while reducing the distance between the projection device 2 and the projection screen 1, which is very suitable for application in laser television and other scenes.

[0063] As shown in FIG. 1, the projection screen 1 is usually rectangular in shape, and the side edges of the bottom and the top thereof are usually parallel to the horizontal direction x, the side edges of the two sides are parallel to the vertical direction y, and the horizontal direction x and the vertical direction y are perpendicular to each other. The embodiment of the present application takes the projection device 2 being arranged at a position close to the side edge of the bottom of the projection screen 1 as an example for illustration.

[0064] FIG. 2 is a projection screen used in cooperation with a front projection system. As shown in FIG. 2, the projection screen includes a polarizing layer 11, a Fresnel lens layer 12 and a reflecting layer 13.

[0065] The polarizing layer 11 is located on the side close to the viewer, the Fresnel lens layer 12 is located on the side of the polarizing layer 11 away from the viewer, and the reflecting layer 13 is located on the surface of the Fresnel lens layer 12.

[0066] FIG. 3 is a schematic view of the planar structure of the Fresnel lens layer. As shown in FIGS. 2 and 3, the Fresnel lens layer 12 includes a plurality of lens units 121 arranged according to a set rule. As shown in FIG. 3, these lens units 121 can constitute concentric circles arranged in a radial direction in sequence. When the projection screen is applied to an ultra-short focus projection system, the center O of the concentric circular lens units 121 is usually not located in the projection screen. When the projection device emits projection light to the projection screen from the lower side of the projection screen, the center O of each lens unit 121 is located below the side edge of the bottom of the projection screen and on the extension line of the symmetry axis I-I’ of the projection screen. In the direction from the bottom to the top of the projection screen, the radius of the lens unit 121 gradually increases, and the projection screen does not contain a complete circular lens, but only contains a partial circular arc-shaped lens.

[0067] As shown in FIG. 2, each lens unit 121 includes a lens surface x1 and a non-lens surface x2 connected to each other. The lens surface x1 is arranged obliquely relative to a plane on which the projection screen is located, and the oblique angle of the lens surface x1 is set according to the incident direction of the projection light and the required exit direction of the light, so that the projection light can be reflected toward the viewer when the projection light is incident on the reflecting layer 13 of the lens surface x1. The non-lens surface x2 is used to connect the lens surface x1, and can be a plane or a curved surface.

[0068] The reflecting layer 13 covers at least the lens surface x1 of each lens unit 121 of the Fresnel lens layer 12. Since the oblique angle of the lens surface x1 of each lens unit 121 is set to reflect the incident projection light toward the viewer, and the reflecting layer 13 covers the lens surface x1 of the lens unit 121 and has the same oblique angle as the lens surface x1, the incident projection light can be reflected toward the viewer according to the original design.

[0069] The Fresnel lens layer 12 is arranged in the projection screen, and the reflecting layer 13 covers the lens surface x1 of each lens unit 121 of the Fresnel lens layer, which is beneficial to reflect the projection light toward the front of the projection screen, thereby improving the gain of the projection screen.

[0070] The projection screen is easily affected by external light when viewed under strong light, so that the image contrast is reduced when watching a movie or the like in a dark scene in a scene with strong ambient light, thereby affecting the viewing experience.

[0071] Therefore, as shown in FIG. 4, the reflecting layer 13 on the surface of the Fresnel lens layer 12 can be replaced by a reflecting structure layer F. The reflecting structure layer F uses the principle of resonance enhancement of light of a set wavelength, and can selectively enhance the reflection of the projection light emitted by the projection device, while absorbing light of other wavelengths, so that the reflectivity of the reflecting structure layer F to the projection light emitted by the projection device is greater than that to light of other wavelengths. The reflecting structure layer F can achieve 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 projection image.

[0072] In some embodiments, as shown in FIG. 5, the reflecting structure layer F can include a semi-transparent layer 131, a reflecting layer 132, and a resonance layer 133. The semi-transparent layer 131, the resonance layer 133, and the reflecting layer 132 are sequentially formed on the lens surface of each lens unit of the Fresnel lens layer. The semi-transparent layer 131, the resonance layer 133, and the reflecting layer 132 constitute a resonance structure.

[0073] The semi-transparent light layer 131 has the property of semi-transmission and semi-reflection. It should be noted that the semi-transmission and semi-reflection property mentioned in the embodiments of the present application is not that the transmission and reflection rates of light are both 50%, but to show that the semi-transparent light layer 131 can realize the property of partially transmitting and partially reflecting light, and the transmission and reflection rates can be adjusted according to actual requirements, and the specific transmission and reflection rates of the semi-transparent light layer 131 are not limited. The semi-transparent light layer 131 can make the projection light incident into the resonant structure when the projection light is incident on the projection screen, and the projection light can also be emitted out of the semi-transparent light layer 131 after being enhanced in the resonant structure.

[0074] In specific implementation, the semi-transparent light layer 131 can be formed by a laminated structure of at least one metal or two or more metals selected from Al, Nb, Ag and Ti. The thickness of the semi-transparent light layer 131 can be controlled to be between 2 nm and 20 nm, so that the semi-transparent light layer 131 has a certain light transmission and also has light reflection.

[0075] The light reflection layer 132 has the function of reflecting light. The light reflection layer 132 is located away from the audience and does not need to transmit light, and therefore can be made of a material having the reflection property and no light transmission property.

[0076] In specific implementation, the light reflection layer 132 can be made of Al, an aluminum alloy, Ag or a silver alloy, and the thickness of the light reflection layer 132 is greater than the thickness of the semi-transparent light layer 131. The thickness of the light reflection layer 132 needs to be greater than 50 nm to make the light reflection layer 132 have a better reflection efficiency.

[0077] The resonant layer 133 is located between the semi-transparent light layer 131 and the light reflection layer 132, and the product of the optical thickness and the refractive index of the resonant layer 133 determines the cavity length of the resonant structure. Therefore, when designing the resonant structure, a dielectric material needs to be selected, and the product of the refractive index and the optical thickness of the dielectric material satisfies the condition of resonating the projection light emitted by the projection device.

[0078] In specific implementation, the resonant layer 133 can be made of a metal oxide, a nitride or a transparent resin.

[0079] If the reflection rate of the semi-transparent light layer 131 is r H , the transmission rate is t H , the reflection rate of the light reflection layer 132 is r M , the incident light electric field intensity incident on the wavelength selection light reflection layer is Ei, and the reflected light electric field intensity reflected by the reflection structure layer is Er, then:

[0080] When the resonance becomes the maximum phase, the following equation is established:

[0081] m is a natural number.

[0082] If the relationship of the cavity length of the resonance structure is used, it can be rewritten as: 2nL = mλ; m is a natural number.

[0083] Wherein, n is the refractive index of the resonance layer, and L is the optical thickness of the resonance layer.

[0084] As can be seen from the above relationship, when a dielectric material with a suitable refractive index is selected as the resonance layer and the resonance layer is set to a suitable optical thickness, the reflection of the projection light by the resonance cavity can be enhanced.

[0085] In the embodiments of the present application, the projection light source can use a three-color laser light source device, which can emit red laser light, green laser light and blue laser light. By adjusting the material refractive index and optical thickness of the resonance layer, the resonance cavity can simultaneously enhance the reflection of red laser light, green laser light and blue laser light, while attenuating the reflection of light of other wavebands, thereby improving the contrast of the projection light.

[0086] FIG. 6 is a reflectivity curve of the reflection structure layer for different wavebands of light according to an embodiment of the present application. As can be seen from FIG. 6, the reflection structure layer provided in the embodiments of the present application can have a relatively high reflectivity for the red laser light, green laser light and blue laser light emitted by the projection device, while the reflectivity for other wavebands is significantly reduced, which is conducive to improving the contrast of the projection light.

[0087] In some embodiments, the reflection structure layer F only includes a resonance layer, which is a single-layer thin film. The material of the resonance layer can be a semiconductor or a semiconductor compound. Since the semiconductor material has the characteristics of both metal material and dielectric material, the incident light can be reflected on both sides of the resonance layer. By adjusting the refractive index and optical thickness of the resonance layer, the resonance enhancement effect of the projection light reflected by both sides of the resonance layer can be achieved. The use of a single-layer semiconductor thin film can achieve selective reflection of the projection light, thereby simplifying the resonance structure and making the manufacturing process simpler. After selecting a suitable refractive index material, only the optical thickness needs to be controlled, which is conducive to reducing production costs and improving production efficiency.

[0088] In the embodiments of the present application, in order to make the reflection structure layer F have a relatively high efficiency, the projection light source uses a laser light source. The difference between laser light and general illumination light is that laser light has polarization. Therefore, the use of a polarizing layer in the projection screen can improve the contrast of the projection light.

[0089] Specifically, the polarizing layer 11 can adopt a transmissive polarizing plate, and specifically can adopt an iodine-based linear polarizing plate or a dye-based linear polarizing plate. In addition, the polarizing layer 11 can also include a metal grating structure, and a light-absorbing coating can be coated on the surface of the metal grating structure to prevent light reflection. The thickness of the polarizing layer 11 can be controlled in the range of 50 μm to 500 μm, so as to achieve a polarizing degree of 80% to 100%.

[0090] As shown in FIG. 7, the polarizing layer 11 has a transmission axis and an absorption axis, which are perpendicular to each other. When the polarization direction of linearly polarized light is parallel to the transmission axis, the linearly polarized light can be completely transmitted through the polarizing layer. When the polarization direction of linearly polarized light is perpendicular to the transmission axis, i.e., parallel to the absorption axis, the linearly polarized light will be completely absorbed. When the polarization direction of linearly polarized light is between the transmission axis and the absorption axis, and has a certain angle with the transmission axis, the intensity of the transmitted linearly polarized light is determined by the following formula: I = I0 x cos 2 θ;

[0091] wherein I0 represents the intensity of linearly polarized light before passing through the polarizing layer, I represents the intensity of linearly polarized light transmitted by the polarizing layer, and θ represents the included angle between the polarization direction of linearly polarized light and the transmission axis of the polarizing layer.

[0092] As for natural light, only half of the light can be transmitted by the polarizing layer, and the other half of the light is absorbed by the polarizing layer. Therefore, if the intensity of natural light is I0, the intensity after passing through the polarizing layer becomes I0 / 2.

[0093] The contrast ratio of the projection screen can be calculated by the ratio of white gain and black gain. The ordinary illuminating light has no polarization and can be regarded as natural light, and the laser light emitted by the laser light source is linearly polarized light. If the polarization direction of the laser light is parallel to the transmission axis of the polarizing layer, the following formula can be used to calculate the increase multiple of the contrast ratio of the projection screen: C p / C0=(I Wp / I B ) / (I W0 / I B )=I Wp / I W0 =I0×cos 2 (0) / (I0 / 2)=2;

[0094] wherein C p represents the contrast ratio of the projection screen when the laser light source is used, C0 represents the contrast ratio of the projection screen when the ordinary illuminating light source is used, I Wp represents the maximum brightness of the projection screen when the laser light source is used, I W0 represents the maximum brightness of the projection screen when the ordinary illuminating light source is used, and I B represents the minimum brightness of the projection screen.

[0095] Since the minimum brightness of the projection screen corresponds to the black gain of the projection screen, the minimum brightness is the same regardless of the light source used, therefore, by using a polarizing layer in the projection screen, and using a laser light source as the projection light source, a contrast ratio of 2 times compared to using a normal light source can be obtained.

[0096] In specific implementation, the projection light emitted by the projection device is laser light with a set polarization direction. Since the relative position of the projection device and the projection screen is fixed, the projection light emitted by the projection device has different angles when incident on different positions of the projection screen, and the polarization direction also changes. As shown in FIG. 8, the projection screen is usually an axisymmetric structure, the two parts divided by the axis of symmetry I-I' are called the left half and the right half, and the intersection of the bottom side of the projection screen and the axis of symmetry I-I' is the bottom center A of the projection screen, and the intersection of the top side of the projection screen and the axis of symmetry I-I' is the top center B of the projection screen. The direction of the transmission axis of the polarizing layer 11 is parallel to the vertical direction y, and the projection device is usually located below the axis of symmetry I-I' of the projection screen. The incident angle and the polarization direction of the projection light incident on the left half and the right half are mutually symmetrical. Hereinafter, the right half of the projection screen is taken as the observation object, and when the projection light is incident on a 100-inch projection screen, the angle between the polarization direction of the projection light and the transmission axis of the polarizing layer satisfies the angle distribution shown in FIG. 9.

[0097] As can be seen from FIG. 9, when the projection light is incident on a position close to the axis of symmetry of the screen, the angle between the polarization direction of the projection light and the transmission axis of the polarizing layer is small, and the minimum angle is 0°; when the projection light is incident on the edges close to the bottom sides of the screen, the angle between the polarization direction of the projection light and the transmission axis of the polarizing layer is large, and the maximum angle can reach 30°, and when the size of the projection screen is larger, the angle will further increase. Due to the change of the angle between the polarization direction of the projection light and the transmission axis of the polarizing layer, the transmittance of the projection light at different positions of the polarizing layer is different. When the angle between the polarization direction of the incident projection light and the transmission axis of the polarizing layer is 30°, the increase multiple of the contrast ratio of the projection screen is: p / C0= I0 x cos 2 (30°) / (I0 / 2) = 1.5;

[0098] When the angle between the polarization direction of the projection light and the transmission axis of the polarizing layer is 0°, the contrast ratio of the projection screen can be increased by 2 times, and thus the gain of different regions of the projection screen is related to the angle between the polarization direction of the projection light and the transmission axis of the polarizing layer when the projection light is incident to the region, and the white gain distribution of the projection screen is shown in FIG. 10. As shown in FIG. 10, the white gain of the region close to the symmetry axis of the projection screen is larger, and the white gain of the region close to the bottom edges of the projection screen is smaller. In terms of gain uniformity, the white gain of the projection screen can have a difference of about 25%, and the gain uniformity of the projection screen is not high.

[0099] The product of the optical thickness and the refractive index of the resonance layer 133 can affect the wavelength of resonance enhancement, and the resonance layer 133 can be manufactured by evaporation or sputtering process. It should be noted that, as shown in FIG. 11, when the deposition source S (which can be an evaporation source or a sputtering source) deposits the resonance layer on the surface of each lens unit 121 of the Fresnel lens layer, the deposition material grows in the direction perpendicular to the deposition source S, and thus the thickness of the resonance layer deposited by the deposition source S is the thickness perpendicular to the deposition source S, which is referred to as the physical thickness pt. When calculating the wavelength of resonance enhancement of the resonance layer, the thickness referred to is the thickness of the resonance layer perpendicular to the lens surface of the lens unit 121, which is referred to as the optical thickness ot. As shown in FIG. 11, the relationship between the physical thickness pt and the optical thickness ot is related to the tilt angle θ of the lens unit 121: ot=pt×cosθ.

[0100] In order to make the projection light incident to the projection screen reflect to the position of the viewer, the tilt angle of the lens surface of each lens unit 121 in the projection screen gradually changes. Taking a projection system in which the projection device is located below the projection screen as an example, the tilt angle of the lens surface of each lens unit 121 increases with the increase of the radius of each lens unit, and the distribution of the tilt angle of the lens surface of each lens unit 121 is shown in FIG. 12. Still taking a 100-inch projection screen as an example, each lens unit 121 is concentrically arranged, and the center is located on the symmetry axis of the projection screen. Along the direction from the bottom center A to the top center B of the projection screen, the tilt angle of each lens unit gradually increases, and the minimum tilt angle of the lens unit is about 5°, and the maximum tilt angle of the lens unit is about 25°.

[0101] When the reflective structure layer adopts the resonant structure composed of the semi-transparent layer 131, the resonant layer 133 and the reflective layer 132, and the material of the resonant layer 133 is Nb2O5, the design thickness of the resonant structure is 10nm / 600nm / 50nm. According to the optical thickness of the resonant layer being 600nm, the physical thickness of the resonant layer is converted, and when the resonant layer 133 is deposited on the Fresnel lens layer, the distribution of the optical thickness ot of the resonant layer in the plane of the projection screen is shown in Fig. 13. In the area where the tilt angle of the lens unit is smaller, the optical thickness of the resonant layer is relatively larger; in the area where the tilt angle of the lens unit is larger, the optical thickness of the resonant layer is relatively smaller. Finally, the optical thickness of the resonant layer forms a trend of gradually decreasing along the radial direction of each lens unit, and the optical thickness of the resonant layer 133 is not uniformly distributed in the projection screen, but varies in the range of 550nm to 600nm.

[0102] When the optical thickness of the resonant layer changes, the reflectivity of the reflective structure layer to different wavelengths will change as shown in Fig. 14: the optical thickness of the resonant layer decreases, and the reflectivity curve of the reflective structure layer moves to the direction of short wavelength. The white gain of the reflective structure layer can be calculated according to the following formula: WG=L=SPD×V(λ)×R(λ);

[0103] Wherein, WG represents the white gain, L represents the brightness, SPD represents the light power distribution, V(λ) represents the photosensitive curve, and R(λ) represents the reflectivity.

[0104] Since the white gain is related to many factors, simulation measurement shows that when the optical thickness of the resonant layer in the reflective structure layer changes in the range of 570nm to 600nm, the change of the white gain is shown in Fig. 15. As can be seen from Fig. 15, when the optical thickness of the resonant layer is in the range of 570nm to 580nm, the white gain of the reflective structure layer is higher, and when the optical thickness of the resonant layer is 600nm, the white gain of the reflective structure layer is lower.

[0105] According to the gain change law shown in Fig. 15, by changing the optical thickness of the resonant layer, the purpose of compensating the decrease of gain uniformity caused by the difference in transmittance of the projection light by the polarizing layer can be achieved. Wherein, in the position where the white gain of the polarizing layer is lower, the optical thickness of the resonant layer corresponds to a higher value of the white gain; in the position where the white gain of the polarizing layer is higher, the optical thickness of the resonant layer corresponds to a lower value of the white gain, and the change of the optical thickness of the resonant layer is used to compensate the gain of the polarizing layer, so as to improve the gain uniformity of the projection screen.

[0106] Specifically, since the projection screen is an axisymmetric structure, the white gain distribution is also symmetrically distributed relative to the symmetry axis, and the adjustment of the optical thickness of the resonant layer can also make the optical thickness of the resonant layer symmetrically distributed relative to the symmetry axis of the projection screen.

[0107] As shown in FIG. 16, when the optical thickness of the resonance layer is controlled in the range of 570 nm to 600 nm, the optical thickness of the region of the resonance layer close to the symmetry axis needs to be greater than the optical thickness of the region far from the symmetry axis. The greater the optical thickness of the resonance layer, the closer to 600 nm, the smaller the corresponding white gain, and the position of the resonance layer corresponding to the position of the polarizing layer with greater white gain (the position close to the symmetry axis) needs to be increased. The smaller the optical thickness of the resonance layer, the closer to 570 nm to 580 nm, the greater the corresponding white gain, and the position of the resonance layer corresponding to the position of the polarizing layer with smaller white gain (the position close to the two side edges of the bottom of the screen) needs to be decreased. Thus, the white gain distribution of the reflection structure layer formed by the change of the optical thickness of the resonance layer can compensate for the gain difference of different regions of the polarizing layer.

[0108] As shown in FIG. 17, the resonance layer 133 includes a first region Z1 which is axially symmetric with respect to the symmetry axis I-I' and is located in the middle region of the projection screen. The direction from the center A of the bottom of the projection screen to the center B of the top is referred to as the first direction, and the width w of the first region Z1 perpendicular to the direction of the symmetry axis I-I' gradually increases along the first direction A-B. Moreover, the optical thickness of the resonance layer in the first region Z1 is equal to the optimal optical thickness when the resonance layer is optically designed.

[0109] As described above, the tilt angle of each lens unit of the Fresnel lens layer increases along the radius of the lens unit, and if the physical thickness of the resonance layer is unchanged, the optical thickness of the resonance layer formed on each lens unit gradually decreases along the radial direction of the lens unit. However, the embodiment of the present application needs to keep the optical thickness of the resonance layer in the first region Z1 unchanged, and thus the physical thickness of the resonance layer 133 needs to gradually increase along the first direction A-B when the resonance layer is deposited.

[0110] As shown in FIG. 17, along the direction perpendicular to the symmetry axis I-I' and gradually away from the symmetry axis, the region of the resonance layer 133 close to the bottom of the projection screen is referred to as the second region Z2, and the region of the resonance layer 133 close to the top of the projection screen is referred to as the third region Z3. Since the lens units in the Fresnel lens layer are arranged in concentric circles, the tilt angle of the lens units in the same circular arc is equal, and thus along the direction perpendicular to the symmetry axis I-I' and gradually away from the symmetry axis, the change degree of the tilt angle of the lens units of the Fresnel lens layer in the second region Z2 is greater than that in the third region Z3. Moreover, the optical thickness of the resonance layer has a cosine relationship with the physical thickness, and thus when the physical thickness of the resonance layer gradually increases along the first direction A-B, the change degree of the optical thickness of the resonance layer in the second region Z2 is greater than that in the third region Z3.

[0111] Thus, the optical thickness of the resonance layer is adjusted according to the above change rule, and the white gain distribution of the reflection structure layer is shown in FIG. 18. As can be seen from FIG. 18 and FIG. 10, the white gain of the reflection structure layer is larger in the area where the white gain of the polarizing layer is smaller, and the white gain of the reflection structure layer is smaller in the area where the white gain of the polarizing layer is larger. When the polarizing layer and the reflection structure layer with the above white gain distribution are arranged in the same projection screen, the white gain distribution of the projection screen is shown in FIG. 19. As can be seen from FIG. 19, after adjusting the optical thickness of the resonance layer in the reflection structure layer, the gain uniformity of the projection screen is improved compared with the gain uniformity when the optical thickness of the resonance layer is not adjusted. Thus, it can be determined that the effect of compensating the gain difference of the projection screen can be achieved by adjusting the optical thickness of the resonance layer in the reflection structure layer.

[0112] In some embodiments, as shown in FIG. 20, the projection screen further comprises an adhesive layer 14 and a surface functional layer 15. The adhesive layer 14 is located between the polarizing layer 11 and the Fresnel lens layer 12, and is used to adhere the polarizing layer 11 and the Fresnel lens layer 12 to each other. The surface functional layer 15 is located on the side of the polarizing layer 11 away from the Fresnel lens layer 12.

[0113] The surface functional layer 15 can be a diffusion layer. The diffusion layer can diffuse light, so that the divergence angle of the light emitted by the projection screen is enlarged, thereby increasing the viewing angle of the screen.

[0114] In some embodiments, the diffusion layer can be formed on the surface of the polarizing layer 11 by sandblasting or the like, so that the polarizing layer 11 itself has a certain light diffusion function. Alternatively, a film layer mixed with diffusion material can be arranged on the surface of the polarizing layer 11, so that the film layer has a light diffusion function.

[0115] In some embodiments, the diffusion layer can also have the function of anisotropic diffusion. Anisotropic diffusion refers to that the diffusion degree of light in different directions can be different. In the embodiments of the present application, the diffusion degree of light in the horizontal direction x is greater than the diffusion degree of light in the vertical direction y. The projection screen is usually fixed on the wall or hung high during use, or integrated with the projection device in one device. The horizontal direction x refers to the direction parallel to the horizontal plane where the audience is located, and the vertical direction y is perpendicular to the horizontal direction x. Since the viewer does not need a large viewing angle in the vertical direction when watching the projection screen, but needs a large viewing angle in the horizontal direction to expand the viewing range, the anisotropic diffusion layer arranged in the projection screen can diffuse the light in the horizontal direction, thereby expanding the viewing range of the projected image.

[0116] In order to realize the anisotropic diffusion characteristics, a plurality of strip-shaped ridge structures 151 can be arranged, as shown in FIG. 21, the strip-shaped ridge structure 151 can adopt a lenticular structure, or as shown in FIG. 22, the strip-shaped ridge structure 151 can adopt a prism structure. As shown in FIG. 21 and FIG. 22, the axis of the strip-shaped ridge structure 151 is parallel to the vertical direction y, and is arranged along the horizontal direction x in sequence.

[0117] The strip-shaped ridge structure 151 in the anisotropic diffusion layer can be made of an acrylic resin or a thermoplastic polyurethane (TPU) material through an embossing process, which is not limited here.

[0118] In some embodiments, as shown in FIG. 23, the projection screen further includes an absorption layer 16 and an anti-reflection layer 17. The absorption layer 16 is located between the surface functional layer 15 and the reflective structure layer F, for example, it can be arranged between the surface functional layer 15 and the polarizing layer 11. The anti-reflection layer 17 is located on the side of the surface functional layer 15 away from the polarizing layer 11, and is located on the outermost surface of the projection screen.

[0119] In specific implementation, the absorption layer 16 can be mixed with light-absorbing materials, which can adjust the light transmittance of light, thereby further optimizing the contrast of the projected image. The light-absorbing materials can adopt dye, pigment, carbon black and other coloring materials, which have a certain absorption effect on the visible light band. The adhesive material can be arranged on the back of the surface functional layer 15.

[0120] In specific implementation, the anti-reflection layer 17 can adopt a transparent medium material with a refractive index of 1.30-1.45, by making the thickness of the anti-reflection layer 17 k(λ / 4n), k=1, 2, 3…, n is the refractive index of the transparent medium, using the thin film interference principle, the incident light has an anti-reflection effect. The anti-reflection layer 17 is made of a low-refractive material, which can reduce the refractive index difference between the anti-reflection layer 17 and the air medium. The smaller the refractive index difference between adjacent media, the smaller the reflectivity of light at the interface between the two media, and the greater the transmittance.

[0121] On the other hand, the embodiment of the present application also provides a manufacturing method of a projection screen, by changing the deposition conditions, the optical thickness of the resonance layer in the reflective structure layer can be adjusted, so as to improve the gain uniformity of the projection screen.

[0122] As shown in FIG. 24, the manufacturing method of the projection screen includes:

[0123] S10, Fresnel lens layer manufacturing process;

[0124] S20, reflective structure layer manufacturing process;

[0125] S30, a bonding process;

[0126] The Fresnel lens layer can be made by using a UV molding process. Specifically, first, a UV-curable resin is coated on a mold having a Fresnel structure on the surface, and a lens substrate is used to apply pressure to the UV-curable resin, while the UV-curable resin is irradiated with UV light from the side of the transparent substrate. The UV-curable resin is cured while being tightly bonded to the transparent substrate, thereby transferring the Fresnel structure on the mold to the transparent substrate to obtain the Fresnel lens layer.

[0127] The surface of the finished Fresnel lens layer includes a plurality of lens units, and the plurality of lens units are arranged in a circular arc shape in concentric and sequentially expanding manner. Each lens unit includes a lens surface and a non-lens surface, and the transparent surface has a set inclination angle with respect to the plane of the Fresnel lens layer, and the inclination angle of the lens surface increases as the radius of the lens unit increases.

[0128] Then, a reflective structure layer needs to be made on each lens unit of the Fresnel lens layer. In some embodiments, the reflective structure layer adopts a laminated structure composed of a semi-transparent layer, a resonance layer and a reflective layer; in some embodiments, the reflective structure layer can also only include a resonance layer. Regardless of the structure of the reflective structure layer, each film layer included therein can be formed on the surface of the Fresnel lens layer by deposition. The specific form of deposition can be evaporation or sputtering, which is not limited here.

[0129] It is worth noting that if each lens unit of the Fresnel lens layer is arranged facing the back of the projection screen, the deposition sequence of each film layer in the reflective structure layer is to first deposit the semi-transparent layer on the lens unit, then deposit the resonance layer, and finally deposit the reflective layer. If each lens unit of the Fresnel lens layer is arranged facing the front of the projection screen, the deposition sequence of each film layer in the reflective structure layer is to first deposit the reflective layer on the lens unit, then deposit the resonance layer, and finally deposit the semi-transparent layer.

[0130] After the reflective structure layer is deposited on the surface of each lens unit of the Fresnel lens layer, the polarizing layer is bonded to the Fresnel lens layer.

[0131] In the embodiments of the present application, the optical thickness of the resonance layer in the reflective structure layer needs to satisfy a special distribution rule. In order to make the optical thickness of the resonance layer satisfy the above special distribution, a mask plate can be arranged between the deposition source and the Fresnel lens layer when the resonance layer is deposited, and the mask plate is specially designed in terms of opening rate, so that the optical thickness of the deposited resonance layer can meet the requirements.

[0132] In some embodiments, the Fresnel lens layer can be made of a flexible material, as shown in FIG. 25, and then the resonant layer can be made by a roll-to-roll process. Specifically, the Fresnel lens layer 12 is arranged on a roller; a mask plate (not shown in FIG. 25) is arranged at the exit position of the deposition source S; and the Fresnel lens layer 12 is rotated relative to the deposition source S during the deposition process, so that the material of the deposition source is deposited on the Fresnel lens layer 12 through the mask plate.

[0133] As shown in FIG. 26, the mask plate m has an opening k, which is shaped like a trapezoid. In order to make the resonant layer gradually increase in physical thickness along the height direction of the projection screen, the opening k of the mask plate can be made to extend along a direction parallel to the symmetry axis of the projection screen, and the width of the opening k perpendicular to the extension direction increases with the increase of the radius of each lens unit.

[0134] As described above, along the height increasing direction of the projection screen (i.e. the first direction A-B described above), if the physical thickness of the resonant layer gradually increases, then as the tilt angle of the lens unit increases, the optical thickness of the resonant layer can be relatively uniform in the area close to the symmetry axis of the projection screen. During the deposition of the resonant layer, the Fresnel lens layer is constantly rotated, and in combination with the feature that the tilt angle of the lens unit with a larger radius is larger, the optical thickness of the resonant layer in the area close to the two side edges of the projection screen can be reduced, and the distribution of the optical thickness of the finally deposited resonant layer is shown in FIG. 16.

[0135] In order to make the physical thickness of the resonant layer gradually increase along the height increasing direction of the projection screen, the shape of the opening of the mask plate m needs to be designed like the trapezoid shown in FIG. 26, and the physical thickness of the resonant layer deposited at the position with a larger width of the opening k is larger, and the physical thickness of the resonant layer deposited at the position with a smaller width of the opening k is smaller. When the width of the opening k of the mask plate m gradually increases along the height increasing direction of the projection screen, the physical thickness of the resonant layer deposited gradually increases along the height increasing direction.

[0136] Further, if it is desired that the change trend of the optical thickness of the resonant layer in the direction away from the symmetry axis satisfies the distribution state shown in FIG. 16, the opening rate of the mask plate also needs to be designed according to the tilt angle of each lens unit of the Fresnel lens layer.

[0137] For example, if the projection ratio of the projection system is 0.22 and the offset is 145%, the variation trend of the opening ratio of the mask plate along the direction of the height increase of the screen is shown in FIG. 27. If the projection ratio of the projection system is 0.20 and the offset is 145%, the variation trend of the opening ratio of the mask plate along the direction of the height increase of the screen is shown in FIG. 28.

[0138] When the projection ratio of the projection system is smaller, it means that the projection size is larger under the same projection distance, or the projection distance is further reduced under the same projection size. The decrease of the projection ratio makes the incident angle of the projection light incident to the projection screen larger, so the tilt angle of the lens unit needs to be increased to make the projection light reflect to the front of the screen. The change of the tilt angle of the lens unit changes the optical thickness of the deposited resonance layer, so the opening ratio of the mask plate needs to be adjusted accordingly to adjust the distribution of the optical thickness of the resonance layer, so as to make the gain of the reflection structure layer and the polarizing layer compensate each other.

[0139] In some embodiments, the resonance layer can also be made by linear deposition, as shown in FIG. 29. Specifically, the Fresnel lens layer 12 is arranged on a moving substrate; a mask plate (not shown in FIG. 29) is arranged above the Fresnel lens layer; and the Fresnel lens layer 12 is relatively moved with respect to the deposition source S during the deposition process, so that the material of the co-deposition source is deposited on the Fresnel lens layer 12 through the mask plate.

[0140] The opening shape of the mask plate m arranged on the surface of the Fresnel lens layer 12 is shown in FIGS. 30 and 31. The mask plate m can be a metal grid with a specific pattern. As shown in FIG. 30, the shape of the opening k of the mask plate m can be a fan shape arranged concentrically and expanding; or as shown in FIG. 31, the shape of the opening k of the mask plate m can be a rectangle, and the size of the opening gradually increases along the direction of the height increase of the screen. In this way, the opening ratio of the mask plate m gradually increases along the direction of the radius increase of each lens unit 121 in the Fresnel lens layer.

[0141] The larger the opening ratio of the mask plate is, the larger the physical thickness of the deposited resonance layer is, and the smaller the opening ratio of the mask plate is, the smaller the physical thickness of the deposited resonance layer is. Therefore, when the opening ratio of the mask plate m gradually increases along the direction of the radius increase of each lens unit 121, the physical thickness of the deposited resonance layer gradually increases along the direction of the radius increase of each lens unit. In combination with the adjustment of the optical thickness of the resonance layer by the tilt angle of the lens unit, the variation trend of the optical thickness of the deposited resonance layer can reach the distribution state shown in FIG. 16.

[0142] In some embodiments, a diffusion layer can also be made on the surface of the polarizing layer, a transmittance-increasing layer can be made on the surface of the diffusion layer, and an absorption layer can be added between the diffusion layer and the polarizing layer, etc., to form a projection screen with different structures or functions.

[0143] Based on the same inventive concept, the embodiments of the present application also provide a projection system, as shown in FIG. 1, which comprises a projection device 2 and a projection screen 1 located on the light exit side of the projection device 2.

[0144] FIG. 32 is a structural schematic diagram of a projection device provided by the embodiments of the present application.

[0145] As shown in FIG. 32, the projection device comprises a light source device 21, an illumination light path 22, a display element 23, and a lens 24. The illumination light path 22 is located on the light exit side of the light source device 21, the display element 23 is located on the light exit side of the illumination light path 22, and the lens 24 is located on the light exit side of the display element 23.

[0146] The light source device 21 can adopt a laser light source device. The laser light source device can adopt a monochromatic laser or a laser that can emit multiple colors of laser light or multiple lasers that emit different colors of laser light. When the laser light source device adopts a monochromatic laser, the laser display device also needs to be provided with a color conversion device (such as a fluorescent wheel) and a color wheel. The color conversion device is used for color conversion, and the color wheel is used for filtering out monochromatic light. The monochromatic laser cooperates with the color conversion device and the color wheel to achieve the purpose of emitting different colors of primary light in time sequence. When the laser light source device adopts a laser that can emit multiple colors of laser light, the laser light source needs to be controlled to emit different colors of laser light as primary light in time sequence.

[0147] In the embodiments of the present application, the light source device can adopt a three-color laser light source device, which can be a laser that emits three primary colors of laser light, such as an MCL laser, etc. Alternatively, the three-color laser light source device can include a red laser, a green laser, and a blue laser that respectively emit three primary colors of laser light. The adoption of the three-color laser light source device is conducive to improving the color gamut of the projected image and has better color performance, which can accurately reproduce the input image.

[0148] The illumination light path 22 is located on the light exit side of the light source device 21. The illumination light path 22 collimates and homogenizes the emitted light of the light source device 21 on one hand, and can make the emitted light of the light source device 21 incident to the display element 23 at a suitable angle on the other hand. The illumination light path 22 can include multiple lenses or lens groups, which are not limited herein.

[0149] The display element 23 is used to modulate the incident light. In a specific implementation, the display element 23 can be a Digital Micromirror Device (DMD). After passing through the illumination light path 22, the light beam meets the illumination size and incident angle required by the DMD. The DMD surface includes a plurality of micro-mirrors, each of which can be individually driven to deflect. By controlling the deflection angle of the DMD, the brightness of the light incident to the lens 24 is controlled.

[0150] The lens 24 is used to image the light emitted by the display element 23, and the imaging is projected after passing through the lens 24.

[0151] In the embodiments of the present application, the projection device 2 can be an ultra-short focus projection device, i.e., the lens 24 in the projection device is an ultra-short focus lens. The use of the ultra-short focus projection device can greatly shorten the distance between the projection device 2 and the projection screen 1, and at the same time realize large-size image display while shortening the projection distance.

[0152] The projection screen 1 is located on the light-emitting side of the lens in the projection device. The projection screen 1 includes a polarizing layer, a Fresnel lens layer, and a reflective structure layer located on the surface of each lens unit of the Fresnel lens layer. The reflective structure layer includes a resonance layer, which can resonate and increase the incident projection light and absorb light of other wavelengths, thereby improving the contrast of the projection light. The optical thickness of the resonance layer at different positions of the projection screen is not uniform. By changing the optical thickness of the resonance layer, the decrease in gain uniformity caused by the difference in transmittance of the projection light by the polarizing layer is compensated, thereby making the gain values at different positions of the projection screen more close, and improving the gain uniformity of the projection screen.

[0153] Although the preferred embodiments of the present application have been described, those skilled in the art can make further changes and modifications to the embodiments once they know the basic inventive concept. Therefore, the appended claims are intended to be interpreted as including all changes and modifications falling within the scope of the present application.

[0154] Obviously, various modifications and changes can be made to the present application by those skilled in the art without departing from the spirit and scope of the present application. Thus, it is intended that the present application cover the modifications and changes as falling within the scope of the claims and their equivalents.

Claims

1. A projection screen, comprising: a polarizing layer, an axis of transmission of the polarizing layer being perpendicular to a horizontal direction; projection light emitted by a projection device to the projection screen being linearly polarized light; a Fresnel lens layer located on a side of the polarizing layer facing away from a viewer; the Fresnel lens layer comprising: a plurality of lens units arranged in concentric and sequentially expanding circular arcs, each of the lens units comprising a lens surface and a non-lens surface, the lens surface being at a set angle with respect to a plane in which the projection screen lies; and a reflective structure layer covering at least the lens surface of each of the lens units of the Fresnel lens layer, the reflective structure layer having a reflectivity to the projection light emitted by the projection device that is greater than a reflectivity to light of other wavelengths, the reflective structure layer comprising: a resonance layer for resonant enhancement of the projection light emitted by the projection device and absorption of light of other wavelengths, an optical thickness of the resonance layer being unevenly distributed in the plane in which the projection screen lies, the optical thickness of the resonance layer being a thickness of the resonance layer perpendicular to the lens surface.

2. The projection screen of claim 1, wherein, the projection screen having an axial symmetry, an axis of symmetry of the projection screen being perpendicular to the horizontal direction; the optical thickness of the resonance layer being symmetrically distributed with respect to the axis of symmetry.

3. The projection screen of claim 2, wherein, the optical thickness of the resonance layer being greater in a region of the resonance layer closer to the axis of symmetry than in a region of the resonance layer farther from the axis of symmetry.

4. The projection screen of claim 3, wherein, the resonance layer comprising a first region having an axial symmetry with respect to the axis of symmetry, a width of the first region perpendicular to the axis of symmetry gradually increasing along a first direction, the first direction being a direction parallel to the axis of symmetry and from a bottom to a top of the projection screen; the optical thickness of the resonance layer being equal in the first region.

5. The projection screen of claim 3, wherein, along a direction perpendicular to the axis of symmetry and gradually away from the axis of symmetry, a degree of change in the optical thickness of the resonance layer is greater in a region of the resonance layer closer to the bottom of the projection screen than in a region of the resonance layer closer to the top of the projection screen.

6. The projection screen of claim 2, wherein, a physical thickness of the resonance layer gradually increasing along the first direction, the first direction being the direction parallel to the axis of symmetry and from the bottom to the top of the projection screen, the physical thickness of the resonance layer being a thickness of the resonance layer perpendicular to the plane in which the projection screen lies.

7. The projection screen of any of claims 1-6, wherein, the reflective structure layer further comprising: a semi-transparent layer located on a side of the resonance layer closer to the polarizing layer; and a reflective layer located on a side of the resonance layer facing away from the semi-transparent layer; the resonance layer being located between the semi-transparent layer and the reflective layer, the semi-transparent layer comprising a laminated structure of at least one or more of aluminum, niobium, silver, and titanium, a thickness of the semi-transparent layer being 2nm-20nm, the reflective layer comprising aluminum, an aluminum alloy, silver, or a silver alloy, a thickness of the reflective layer being greater than 50nm, the resonance layer comprising a metal oxide, a nitride, or a transparent resin, a product of the optical thickness and the refractive index of the resonance layer being 1200-1400.

8. The projection screen of any of claims 1-6, wherein, the reflective structure layer comprising only the resonance layer; the resonance layer comprising a semiconductor or a semiconductor compound. 9.The projection screen of any one of claims 1-6, further comprising: a surface functional layer on a side of the polarizing layer away from the Fresnel lens layer; and an adhesive layer between the polarizing layer and the Fresnel lens layer; wherein the surface functional layer is a diffusion layer.

10. The projection screen of claim 9, further comprising: an absorption layer between the surface functional layer and the reflective structure layer; and / or an anti-reflection layer on a side of the surface functional layer away from the polarizing layer.

11. A projection system, comprising: a projection device for emitting projection light, the projection light being linearly polarized light; and a projection screen on an emission side of the projection device, the projection screen being the projection screen of any one of claims 1-10; the projection light emitted by the projection device to the projection screen being obliquely incident on the projection screen; wherein the projection device is an ultra-short focus laser projection device; the projection device comprising: a three-color laser light source device for emitting three primary color lasers; a display element on an emission side of the three-color laser light source device for modulating incident light to form an image beam for image display; and a lens on an emission side of the display element.

12. A method for manufacturing a projection screen, comprising: a Fresnel lens layer manufacturing process; the Fresnel lens layer comprising a plurality of lens units, the plurality of lens units being arranged in concentric and sequentially expanding circular arcs; each of the lens units comprising a lens surface and a non-lens surface; a reflective structure layer manufacturing process: manufacturing a reflective structure layer on each of the lens units of the Fresnel lens layer; the reflective structure layer comprising a resonance layer; an adhesive process: adhering a polarizing layer to the Fresnel lens layer with the reflective structure layer; wherein the optical thickness of the resonance layer is unevenly distributed in the plane of the projection screen; the optical thickness of the resonance layer being the thickness of the resonance layer perpendicular to the lens surface.

13. The production method according to claim 12, wherein In the reflective structure layer manufacturing process, the manufacturing process of the resonance layer specifically comprises: setting the Fresnel lens layer on a reel; setting a mask plate at the emission position of a deposition source; depositing the resonance layer on the Fresnel lens layer while rotating the Fresnel lens layer relative to the deposition source; wherein the mask plate has an opening, the opening extending along a direction parallel to the symmetry axis of the projection screen, and the width of the opening perpendicular to the extending direction increases with the increase of the radius of each lens unit.

14. The production method according to claim 12, wherein In the reflective structure layer manufacturing process, the manufacturing process of the resonance layer specifically comprises: setting the Fresnel lens layer on a moving substrate; setting a mask plate above the Fresnel lens layer; depositing the resonance layer on the Fresnel lens layer while moving the Fresnel lens layer relative to the deposition source; wherein the opening rate of the mask plate increases with the increase of the radius of each lens unit in the Fresnel lens layer.

15. The production method according to claim 14, wherein The opening of the mask plate is rectangular or sector-shaped.

Images