Projection screen, manufacturing method thereof and projection system

Abstract

A projection screen (1), a manufacturing method and a projection system, the projection screen (1) comprising a diffusion layer (11), a Fresnel structure layer (12) and a wavelength selective reflection layer (F) located on at least part of the surface of a Fresnel structure (121) of the Fresnel structure layer (12), the wavelength selective reflection layer (F) being capable of selectively reflecting projection light emitted by a projection device (2), according to the invention, the light reflection rate of the projection device (2) is greatly reduced, the black appearance can be realized when the projection device (2) is turned off, and bright display can be realized when the projection device (2) is turned on, so that the contrast of a projected image can be improved.

Description

Projection screen, method for making same and projection system

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the priority of the Chinese patent application filed with the China Patent Office on December 29, 2022, with application number 202211716475.1 and application name “Projection screen and projection system”, the entire contents of which are incorporated by reference into this application; this application claims the priority of the Chinese patent application filed with the China Patent Office on December 29, 2022, with application number 202211716324.6 and application name “Projection screen and projection system”, the entire contents of which are incorporated by reference into this application; this application claims the priority of the Chinese patent application filed with the China Patent Office on February 10, 2023, with application number 202310107687.8 and application name “Projection screen, method for manufacturing the same and projection system”, the entire contents of which are incorporated by reference into this application.

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

[0004] With the popularity of laser display products, the market for laser TVs, as large-screen products that replace LCD TVs and organic electroluminescent (EL) TVs, is expanding rapidly. The current front projection system can usually be used with a projection screen. The projection device emits projection light, which is incident on the projection screen and then reflected by the projection screen to the human eye, so that the projected image can be seen.

[0005] White frosted projection screens can evenly reflect light from the light source and are inexpensive. However, white frosted projection screens are easily affected by external light when viewed under strong light, and are not suitable for watching movies and other images that often use dark scenes. In order to overcome the above problems, there are also screens that can color the projection screen to absorb ambient light and reduce the brightness of the ambient light. However, since the colored projection screen also absorbs the emitted light of the projection light source, the brightness of the projection light is lost, resulting in a decrease in image contrast.

[0006] Summary of the invention

[0007] According to a first aspect of an embodiment of the present application, a projection screen is provided, comprising:

[0008] Diffusion layer;

[0009] A Fresnel structure layer is located on one side of the diffusion layer; a surface of one side of the Fresnel structure layer has a Fresnel structure; and

[0010] A wavelength selective reflection layer covers at least a portion of the surface of the Fresnel structure of the Fresnel structure layer; the reflectivity of the wavelength selective reflection layer to the projection light emitted by the projection device is greater than the reflectivity of light in other wavelength bands.

[0011] According to a second aspect of an embodiment of the present application, a method for manufacturing a projection screen is provided, comprising:

[0012] Fresnel structure manufacturing process: manufacturing a Fresnel structure layer; a surface of one side of the Fresnel structure layer has a plurality of Fresnel structures, and the Fresnel structures include inclined surfaces and connecting surfaces connected to each other;

[0013] Reflective layer manufacturing process: forming a discontinuous first film on the inclined surface of the Fresnel structure, and forming a continuous second film layer on the first film;

[0014] Surface functional layer manufacturing process: forming a surface functional layer on one side surface of the Fresnel structure layer with the reflective layer.

[0015] According to a third aspect of an embodiment of the present application, a projection system is provided, comprising:

[0016] A projection device for emitting projection light; and

[0017] A projection screen, located at the light-emitting side of the projection device, the projection screen being the above-mentioned projection screen;

[0018] Wherein, the projection device is an ultra-short-throw laser projection device; the projection device comprises:

[0019] A three-color laser light source device, used for emitting three-primary-color lasers;

[0020] A light modulation component, located at the light output side of the three-color laser light source device, and used to modulate the output laser of the three-color laser light source device;

[0021] The projection lens is located at the light-emitting side of the light modulation component.

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments of the present application. It should be noted that the drawings introduced below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0023] FIG1 is a schematic diagram of the structure of a projection system provided in an embodiment of the present application;

[0024] FIG. 2 is a schematic diagram of a structure of a projection screen in the related art;

[0025] FIG3 is a second schematic diagram of the structure of a projection screen in the related art;

[0026] FIG4 is one of the structural schematic diagrams of the projection screen provided in the embodiment of the present application;

[0027] FIG5 is one of the structural schematic diagrams of the wavelength selective reflection layer provided in an embodiment of the present application;

[0028] FIG6 is a second schematic diagram of the structure of the wavelength selective reflection layer provided in an embodiment of the present application;

[0029] FIG7 is a reflectivity curve of the wavelength selective reflection layer provided in an embodiment of the present application to light of different wavelength bands;

[0030] FIG8 is an intensity distribution curve of ambient light provided in an embodiment of the present application;

[0031] FIG9 is a reflectivity curve of ambient light incident on a wavelength selective reflective layer provided by an embodiment of the present application;

[0032] FIG. 10 is a curve showing the relationship between the thickness of the semi-transmissive layer and the attenuation rate of the ambient light intensity provided in an embodiment of the present application;

[0033] FIG11 is one of the relationship curves between wavelength and reflectivity provided in an embodiment of the present application;

[0034] FIG. 12 is a second curve showing the relationship between wavelength and reflectivity provided in an embodiment of the present application;

[0035] FIG. 13 is a third curve showing the relationship between wavelength and reflectivity provided in an embodiment of the present application;

[0036] FIG. 14 is a fourth curve showing the relationship between wavelength and reflectivity provided in an embodiment of the present application;

[0037] FIG. 15 is a fifth curve showing the relationship between wavelength and reflectivity provided in an embodiment of the present application;

[0038] FIG. 16 is a sixth curve showing the relationship between wavelength and reflectivity provided in an embodiment of the present application;

[0039] FIG17 is a second schematic diagram of the structure of the projection screen provided in an embodiment of the present application;

[0040] FIG18 is a comparison diagram of reflectivity curves of light at different incident angles provided in an embodiment of the present application;

[0041] FIG19 is a third schematic diagram of the structure of the projection screen provided in the embodiment of the present application;

[0042] FIG20 is a reflectivity curve of the wavelength selective reflection layer provided in an embodiment of the present application for light with an incident angle of 65°;

[0043] FIG21 is a reflectivity curve of a wavelength selective reflection layer provided in an embodiment of the present application for light with an incident angle of 10°;

[0044] FIG22 is a reflectivity curve after two reflections through the wavelength selection layer provided in an embodiment of the present application;

[0045] FIG23 is a relative intensity curve of ambient light incident on a projection screen provided by an embodiment of the present application;

[0046] FIG. 24 is a relative intensity curve of ambient light after being reflected by a projection screen provided by an embodiment of the present application;

[0047] FIG25 is a fourth structural schematic diagram of a projection screen provided in an embodiment of the present application;

[0048] FIG26 is a fifth structural schematic diagram of a projection screen provided in an embodiment of the present application;

[0049] FIG27 is a sixth structural schematic diagram of a projection screen provided in an embodiment of the present application;

[0050] FIG28 is a seventh structural schematic diagram of a projection screen provided in an embodiment of the present application;

[0051] FIG29 is an eighth structural schematic diagram of a projection screen provided in an embodiment of the present application;

[0052] FIG30 is a ninth structural schematic diagram of a projection screen provided in an embodiment of the present application;

[0053] FIG31 is a tenth structural schematic diagram of a projection screen provided in an embodiment of the present application;

[0054] FIG32 is a third schematic diagram of the structure of a projection screen in the related art;

[0055] FIG33 is a fourth schematic diagram of the structure of a projection screen in the related art;

[0056] FIG34 is a flow chart of a method for manufacturing a projection screen provided in an embodiment of the present application;

[0057] FIG35 is a schematic diagram of one of the manufacturing processes of the Fresnel structure layer provided in an embodiment of the present application;

[0058] FIG36 is a second schematic diagram of the manufacturing process of the Fresnel structure layer provided in an embodiment of the present application;

[0059] FIG37 is a coating thickness curve in the related art;

[0060] FIG38 is a coating thickness curve provided in an embodiment of the present application;

[0061] FIG39 is one of the structural schematic diagrams of the reflective layer in the coating process provided in an embodiment of the present application;

[0062] FIG40 is a second schematic diagram of the structure of the reflective layer in the coating process provided in an embodiment of the present application;

[0063] FIG41 is a third schematic diagram of the structure of the reflective layer in the coating process provided in an embodiment of the present application;

[0064] FIG42 is a fourth schematic diagram of the structure of the reflective layer in the coating process provided in an embodiment of the present application;

[0065] FIG43 is an eleventh structural diagram of a projection screen provided in an embodiment of the present application;

[0066] FIG44 is a twelfth structural diagram of a projection screen provided in an embodiment of the present application;

[0067] Figure 45 is a schematic diagram of the structure of the projection device provided in an embodiment of the present application.

[0068] Among them, 1-projection screen, 2-projection device, 10-surface layer, 11-diffusion layer, 11'-surface functional layer, 111-second substrate, 112-diffusion material, 12-Fresnel structure layer, 121-Fresnel structure, x1-inclined surface, x2-connecting surface, 122-third substrate, 13-reflective material layer, 13'-reflective layer, 14-adhesive layer, F-wavelength selective reflection layer, 131-semi-transparent layer, 132-reflective layer, 133-transparent medium layer, 134-first substrate, 21-light source device, 22-illumination optical path, 23-light modulation component, 24-projection lens, s1-first film, s2-second film layer, f'-ultraviolet curing resin, M-mold, C-ambient light, L-projection light.

[0069] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application will be further described below in conjunction with the drawings and examples. However, the example embodiments can be implemented in various forms and should not be understood as being limited to the embodiments described herein; on the contrary, these embodiments are provided to make the present application more comprehensive and complete, and to fully convey the concepts of the example embodiments to those skilled in the art. The same figure marks in the figures represent the same or similar structures, and thus their repeated descriptions will be omitted. The words expressing position and direction described in this application are all explained using the drawings as examples, but changes can be made as needed, and the changes made are all included in the scope of protection of this application. The drawings of this application are only used to illustrate the relative position relationship and do not represent the true proportion.

[0070] With the popularity of laser display products, the market for laser TVs has expanded rapidly as a large-screen product to replace LCD TVs and organic EL TVs. In order to achieve better brightness and display effects, projection equipment is generally used with a projection screen.

[0071] FIG. 1 is a schematic diagram of the structure of a projection system provided in an embodiment of the present application.

[0072] As shown in FIG. 1 , the projection system includes: a projection device 2 and a projection screen 1 .

[0073] The projection screen 1 is located on the light emitting side of the projection device 2. The audience faces the projection screen 1. The projection device 2 emits projection light, which is incident on the projection screen 1 and reflected toward the audience after passing through the projection screen 1, so that the audience can watch the projected image.

[0074] The ultra-short-throw projection device has the characteristics of a short projection distance and a large projection screen, and is very suitable for application in the home field. The projection system provided in the embodiment of the present application can adopt the ultra-short-throw projection device.

[0075] The projection screen used in the current front projection projection system is provided with a Fresnel structure, which has a specific tilt angle, so that the projection light emitted by the projection device can be reflected toward the audience after entering the reflective material on the Fresnel structure, so that more projection light can enter the human eye.

[0076] FIG. 2 is one of the structural schematic diagrams of a projection screen in the related art.

[0077] As shown in FIG2 , the projection screen includes: a surface layer 10, a Fresnel structure layer 12 and an adhesive layer 14, wherein the surface layer 10 and the Fresnel structure layer 12 are bonded to each other via the adhesive layer 14. The side of the Fresnel structure layer 12 facing away from the surface layer 10, that is, the side facing away from the audience, has a Fresnel structure, and a reflective material layer 13 is formed on the surface of the Fresnel structure. The reflective material layer 13 is usually formed on the surface of the Fresnel structure using a metal with reflective properties such as aluminum, so that light is reflected when incident on the reflective material layer 13 on the surface of the Fresnel structure.

[0078] As shown in FIG. 2 , the projection light L emitted by the projection device is incident on the inside of the projection screen from the side of the surface layer 10 , and is reflected by the reflective material layer 13 on the surface of the Fresnel structure when incident on the Fresnel structure, thereby being reflected in the direction of the audience.

[0079] At the same time, ambient light C is incident on the inside of the projection screen from one side of the surface layer 10. Similarly, some ambient light will be reflected by the reflective material layer 13 when it is incident on the reflective material layer 13 on the surface of the Phil structure, and then emitted from the projection screen. Part of the reflected ambient light can be incident on the human eye, thereby reducing the contrast of the projected image.

[0080] In order to overcome the above problems, the film layer in the projection screen is usually colored so that the colored film layer can absorb the incident ambient light and reduce the reflection of the ambient light.

[0081] FIG. 3 is a second schematic diagram of the structure of a projection screen in the related art.

[0082] As shown in FIG3 , the adhesive layer 14 can be colored, and dyes, carbon black and other light-absorbing substances can be mixed into the material of the adhesive layer 14, so that the ambient light is absorbed when it enters the adhesive layer 14. However, since the colored film layer in the projection screen absorbs light of all wavelengths, the emission efficiency of the projection light L decreases after entering the colored film layer (such as the adhesive layer 14), and the contrast cannot be improved.

[0083] In view of this, an embodiment of the present application provides a projection screen that can selectively reflect the wavelength band of projection light emitted by a projection device, while greatly reducing the reflectivity of light in other wavelength bands, thereby significantly improving the contrast of the projected image.

[0084] FIG. 4 is one of the structural schematic diagrams of the projection screen provided in the embodiment of the present application.

[0085] As shown in FIG. 4 , the projection screen includes: a diffusion layer 11 , a Fresnel structure layer 12 and a wavelength selective reflection layer F.

[0086] The diffusion layer 11 is the outermost film layer of the projection screen, and is located on the side closest to the audience. The diffusion layer 11 has the function of diffusing light. The projection system provided in the embodiment of the present application can use a laser light source. The laser has a high collimation, so the divergence angle of the projection light is small. The light reflected by the projection screen has a high collimation, which also leads to a small field of view angle. By providing the diffusion layer 11, the emission angle of the light after passing through the diffusion layer can be diversified, so that the light finally emitted by the projection screen has a certain divergence angle, which increases the field of view angle of the audience viewing the projected image. In addition, the diffusion layer 11 is also conducive to eliminating laser speckle and optimizing the projection image.

[0087] The Fresnel structure layer 12 is located on one side of the diffusion layer, specifically on the side of the diffusion layer 11 away from the audience. A plurality of Fresnel structures 121 arranged according to a set rule are arranged on the surface of one side of the Fresnel structure layer 12. According to different application scenarios and manufacturing processes, each Fresnel structure 121 can form a concentric circle structure that is sequentially expanded and arranged along the radial direction; or each Fresnel structure 121 is a linear structure that extends along the horizontal direction of the projection screen and is arranged perpendicular to the horizontal direction; or each Fresnel structure 121 is a periodic structure arranged in a checkerboard pattern, which is not limited here.

[0088] As shown in FIG4 , the Fresnel structure 121 includes an inclined surface x1 and a connecting surface x2 connected to each other; wherein the inclined surface x1 is inclined relative to the plane where the diffusion layer 11 is located, and the inclination angle of the inclined surface x1 is set according to the incident angle and reflection angle of the projection light, and the inclination angle of the inclined surface x1 satisfies the reflection of the projection light emitted by the projection device toward the direction of the audience when it is incident on the reflection structure on the surface of the inclined surface x1. When the audience is located directly in front of the projection screen, the inclined surface x1 of each Fresnel structure 121 is used to reflect the incident projection light directly in front. The connecting surface x2 is used to connect the inclined surface x1, and the connecting surface x2 is not used to reflect the projection light.

[0089] The wavelength selective reflection layer F covers at least part of the surface of the Fresnel structure 121 of the Fresnel structure layer 12, and the wavelength selective reflection layer F is used to selectively reflect the incident light. In the embodiment of the present application, the reflectivity of the wavelength selective reflection layer F to the projection light is greater than the reflectivity of the light of other wavelength bands. Therefore, the reflective material layer on the surface of the Fresnel structure 121 is replaced with the wavelength selective reflection layer F. The wavelength selective reflection layer F can selectively reflect the projection light emitted by the projection device, while the reflectivity of the light of other wavelength bands is greatly reduced, so that a black appearance can be achieved when the projection device is turned off, and a bright display can be obtained when the projection device is turned on, thereby significantly improving the contrast of the projected image.

[0090] As shown in FIG4 , the projection light L emitted by the projection device is incident on the inside of the projection screen from the diffusion layer 11 side, and is reflected by the wavelength selective reflection layer F on the surface of the Fresnel structure when incident on the Fresnel structure 121, thereby reflecting in the direction of the audience.

[0091] At the same time, the ambient light C is incident on the inside of the projection screen from one side of the diffusion layer 11. When the ambient light C is incident on the wavelength selective reflection layer F on the surface of the Fresnel structure 121, since the wavelength selective reflection layer F only reflects the projection light and has a low reflectivity for ambient light in other bands, the reflection of the ambient light can be greatly reduced, and the contrast of the projection light can be improved.

[0092] Specifically, the wavelength selective reflection layer F uses the principle of the resonance cavity to select the wavelength of the light emitted toward the audience, while other wavelengths are restricted in the resonance cavity and cannot be emitted, thereby achieving the effect of selective reflection of the projection light.

[0093] FIG. 5 is one of the structural schematic diagrams of the wavelength selective reflection layer provided in an embodiment of the present application.

[0094] As shown in FIG. 5 , the wavelength selective reflection layer F at least includes: a semi-transmissive layer 131 , a reflection layer 132 and a transmissive medium layer 133 .

[0095] The semi-transparent layer 131 is located on the side close to the diffusion layer 11, and is the film layer closest to the audience in the wavelength selective reflection layer F. The reflection layer 132 is located on the side of the semi-transparent layer 131 away from the diffusion layer 11, and is the film layer farthest from the audience in the wavelength selective reflection layer F, and there is a certain distance between the semi-transparent layer 131 and the reflection layer 132. The light-transmitting medium layer 133 is located between the semi-transparent layer 131 and the reflection layer 132, and the semi-transparent layer 131, the reflection layer 132 and the light-transmitting medium layer 133 form a resonant cavity structure.

[0096] The semi-transparent layer 131 has a semi-transparent and semi-reflective property, so that when the projection light is incident on the projection screen, the projection light can be incident on the wavelength selective reflection layer F, and when the projection light is oscillated and enhanced in the resonance cavity, it can also be emitted from one side of the semi-transparent layer 131. The semi-transparent layer 131 can be a laminated structure formed by at least one metal selected from Al, Nb, Ag and Ti, etc., which is not limited here. The semi-transparent layer 131 can be manufactured by sputtering, evaporation and other methods, which is not limited here.

[0097] It should be noted that the semi-transparent layer 131 has a semi-transparent and semi-reflective property, and its transmittance and light reflectance are not limited to 50%. It is intended to illustrate that the semi-transparent layer 131 can partially transmit and partially reflect the light beam. In a specific implementation, it is usually configured to transmit most or a large proportion of the light beam, and reflect a small part or a small proportion of the light beam.

[0098] The reflective layer 132 has the function of reflecting light. The reflective layer 132 is located on the side away from the audience and does not need to transmit light. Therefore, it can be made of a material with reflective properties but no light-transmitting properties. The reflective layer 132 can be made of materials such as aluminum, aluminum alloy, silver or silver alloy, 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 aluminum alloys such as Al and AlSi, or a laminated structure composed of silver alloys such as Ag and AgPaCu, which is not limited here. The reflective layer 132 can be made by sputtering, evaporation and other methods, which is not limited here.

[0099] The thickness of the transparent medium layer 133 determines the cavity length of the resonance cavity. Therefore, the product of the refractive index and thickness of the transparent medium layer 133 determines the wavelength of the light emitted from the resonance cavity to the audience and the wavelength that is extinguished inside the resonance cavity. Therefore, when designing the resonance cavity, it is necessary to select a dielectric material whose product of the refractive index and thickness satisfies the conditions for the projection light emitted by the projection device to resonate. The transparent medium layer 133 can be made of materials such as metal oxides, nitrides or transparent resins. For example, the transparent medium layer 133 can be made of metal oxides or nitrides such as TiO2, Nb2O5, ZrO2, Al2O3, ZnO2, SiO2, etc., and can be made by reactive sputtering, electron beam (EB) evaporation, chemical vapor deposition, etc.; or it can also be made of a laminated structure of one or more of transparent resins such as PMMA, PC, PS, etc., and made by wet processing processes such as gravure printing and die coating, which are not limited here.

[0100] FIG. 6 is a second schematic diagram of the structure of the wavelength selective reflection layer provided in an embodiment of the present application.

[0101] In some embodiments, as shown in FIG6 , the wavelength selective reflection layer F may further include a first substrate 134, and the first substrate 134 is located on a side of the semi-transparent layer 131 away from the transparent medium layer 133. The first substrate serves as a substrate of the resonance cavity and has a supporting and bearing function. In a specific implementation, the first substrate 134 may be made of materials such as polyethylene terephthalate (PET), which is not limited here.

[0102] The resonance principle of the wavelength selective reflection layer is described in detail below.

[0103] If the reflectivity of the semi-transparent layer 131 is rH, and the transmittance is tH; the reflectivity of the reflective layer 132 is rM; the electric field intensity of the incident light incident on the wavelength selective reflective layer is Ei, and the electric field intensity of the reflected light reflected by the wavelength selective reflective layer is Er, then:

[0104] Among them, the resonance becomes the maximum phase when:

[0105] m is a natural number.

[0106] If the relationship of the cavity length of the resonant cavity is adopted, it can be rewritten as:

[0107] 2nL=mλ; m is a natural number.

[0108] Wherein, n is the refractive index of the light-transmitting medium layer, and L is the thickness of the light-transmitting medium layer, that is, the cavity length of the resonant cavity.

[0109] It can be seen from the above relationship that when a dielectric material with a suitable refractive index is selected as the light-transmitting medium layer and the light-transmitting medium layer is set to a suitable thickness, the reflection of the resonant cavity on the projection light can be enhanced.

[0110] In the embodiment of the present application, the projection light source can adopt a three-color laser light source device, which can emit red laser, green laser and blue laser. Then, by adjusting the refractive index and thickness of the material of the transparent medium layer, the resonance cavity can simultaneously enhance the reflection of red laser, green laser and blue laser, while attenuating the reflection of light in other bands, thereby improving the contrast of the projection light.

[0111] FIG7 is a reflectivity curve of the wavelength selective reflection layer provided in an embodiment of the present application for light of different wavelength bands, wherein the position of the dotted line corresponds to the central wavelengths of the red laser, the green laser and the blue laser. As can be seen from FIG7, the wavelength selective reflection layer can have a high reflectivity at the wavelengths of the red laser, the green laser and the blue laser emitted by the projection device at the same time, while the reflectivity at other wavelength bands is significantly reduced, which is beneficial to improve the contrast of the projection light.

[0112] In the specific implementation process, due to the differences in the projection light sources used, the wavelength bands of the lasers emitted by the lasers are not the same, and the emitted lasers usually have a central wavelength with a higher emission energy at the central wavelength. Even when different lasers emit lasers of the same color, their central wavelengths are not the same. For example, the central wavelength of a red laser can be 635nm, 650nm, or 643nm, and due to the manufacturing tolerance of the laser, the central wavelength may fluctuate up and down, for example, the central wavelength of a red laser may fluctuate by ±8nm; the central wavelength of a green laser may be 520nm, 525nm, or 532nm, with a central wavelength fluctuation of ±8nm; the central wavelength of a blue laser may be 445nm or 465nm, with a central wavelength fluctuation of ±8nm.

[0113] When designing the wavelength selective reflection layer, it is necessary to design the refractive index and thickness of the light-transmitting medium layer according to the central wavelength of the light to be reflected. In addition, for an ultra-short-focus projection device, since the distance between the projection device and the projection screen is small, when the projection light emitted by the projection device enters the projection screen, there is light entering the projection screen at a large angle. When the wavelength selective reflection layer is incident at a large angle, a migration of the value of the wavelength selected for reflection will occur. Therefore, in theory, when designing the wavelength selective reflection layer, the narrower the wavelength band range of the light selected for reflection, the better. At the same time, taking into account the compatibility with the projection light source, the embodiment of the present application can make the wavelength selective reflection layer have a floating range of 5nm to 20nm for the central wavelength of the light selected for reflection, and the central wavelength of the light selected for reflection can be 635nm, 650nm or 643nm for red light, 520nm, 525nm or 532nm for green light, and 445nm or 465nm for blue light, which is not limited here.

[0114] FIG8 is an intensity distribution curve of ambient light provided in an embodiment of the present application, and FIG9 is a reflectivity curve of ambient light incident on a wavelength selective reflective layer provided in an embodiment of the present application. Among them, the ambient light intensity distribution curve shown in FIG8 shows the spectral distribution of the CIE standard light source D65. D65 corresponds to the average noon light in Europe / Northern Europe, and is called a daylight light source. The embodiment of the present application uses the D65 light source as the standard light for calculation.

[0115] Comparing Figures 8 and 9, it can be seen that the intensity of the ambient light is attenuated by about 45% after entering the wavelength selective reflection layer. According to Figure 7, the attenuation of the three-color laser caused by the wavelength selective reflection layer is about 20%. Therefore, according to the attenuation rate of the projection light and the ambient light, it can be determined that the intensity of the projection light is (100-20) / (100-45)≈1.45 times the intensity of the ambient light. This improves the contrast of the projection light.

[0116] Based on the above relationship of electric field intensity, the power Pt of the reflected light reflected by the wavelength selective reflection layer is:

[0117] The power of the reflected light is maximum when the sin term is 1, and minimum when the sin term is 0. In order to improve the contrast of the projected light, the reflectivity and transmittance of the semi-transparent layer can be set in such a way that the terms other than the sin term are minimized.

[0118] According to simulation tests, when the central wavelength of the red laser emitted by the projection device is 643nm, the central wavelength of the green laser is 525nm, and the central wavelength of the blue laser is 425nm, the thickness of the semi-transparent layer 131 is in the range of 2nm to 20nm, the thickness of the reflective layer 132 is less than 100nm, and the product of the thickness and the refractive index of the transparent medium layer 133 is in the range of 1200 to 1400, the effect is better. When the reflective layer 132 is made of metal material, it needs to have a certain thickness to have a high reflectivity, so the thickness of the reflective layer 132 needs to be greater than 50nm.

[0119] FIG10 is a curve showing the relationship between the thickness of the semi-transmissive layer and the attenuation rate of the ambient light intensity provided by the embodiment of the present application. In the calculation of the attenuation rate of the ambient light intensity, the D65 light source spectrum is used as a representative. According to the inventive concept of the present application, the higher the attenuation rate of the ambient light, the better the contrast.

[0120] As shown in FIG10 , under the premise that the semi-transparent layer 131 is made of Al, the reflective layer 132 is made of Al, the transparent medium layer 133 is made of Nb2O5, and the first substrate is made of PET, the thickness of the semi-transparent layer with an attenuation rate of more than 40% is approximately 3nm to 12nm, and the maximum ambient light attenuation rate is obtained when the thickness is around 7nm. Therefore, when the wavelength selective reflective layer adopts the above structure, the thickness of the semi-transparent layer 131 can be set to 3nm to 12nm, preferably to 7nm.

[0121] FIG11 is one of the relationship curves between wavelength and reflectivity provided in the embodiment of the present application, FIG12 is the second relationship curve between wavelength and reflectivity provided in the embodiment of the present application, and FIG13 is the third relationship curve between wavelength and reflectivity provided in the embodiment of the present application. Among them, FIG11 to FIG13 are all obtained by simulation under the premise that the semi-transparent layer 131 adopts Al, the reflective layer 132 adopts Al, the transparent medium layer 133 adopts Nb2O5, and the first substrate 134 adopts PET. Under the premise that the thickness of the reflective layer 132 is 200nm and the thickness of the transparent medium layer 133 is 609nm, FIG11 shows the relationship curve between wavelength and reflectivity when the thickness of the semi-transparent layer 131 is 0, FIG12 shows the relationship curve between wavelength and reflectivity when the thickness of the semi-transparent layer 131 is 7nm, and FIG13 shows the relationship curve between wavelength and reflectivity when the thickness of the semi-transparent layer 131 is 30nm.

[0122] As shown in FIG. 11 , when Al is used for the semi-transparent layer, when the thickness is 0, only reflection due to the refractive index difference between the transparent medium layer 133 and the first substrate 134 works, so the wavelength selectivity becomes small.

[0123] As shown in Figures 12 and 13, when the thickness of the semi-transparent layer 131 increases, the transmission component to the resonance cavity decreases, and the reflection component in the semi-transparent layer becomes the main component. When the thickness of the semi-transparent layer 131 is 7nm, the wavelength selection performance is maximized.

[0124] FIG14 is a fourth curve of the relationship between wavelength and reflectivity provided in the embodiment of the present application, FIG15 is a fifth curve of the relationship between wavelength and reflectivity provided in the embodiment of the present application, and FIG16 is a sixth curve of the relationship between wavelength and reflectivity provided in the embodiment of the present application. Among them, FIG14 to FIG16 are all obtained by simulation under the premise that the semi-transparent layer 131 adopts Nb, the reflective layer 132 adopts Al, the transparent medium layer 133 adopts Nb2O5, and the first substrate 134 adopts PET. Under the premise that the thickness of the reflective layer 132 is 200nm and the thickness of the transparent medium layer 133 is 609nm, FIG14 shows the curve of the relationship between wavelength and reflectivity when the thickness of the semi-transparent layer 131 is 0, FIG15 shows the curve of the relationship between wavelength and reflectivity when the thickness of the semi-transparent layer 131 is 15nm, and FIG16 shows the curve of the relationship between wavelength and reflectivity when the thickness of the semi-transparent layer 131 is 70nm.

[0125] As shown in FIG. 14 , when Nb is used for the semi-transparent layer, when the thickness is 0, only reflection due to the refractive index difference between the transparent medium layer 133 and the first substrate 134 works, so the wavelength selectivity becomes small.

[0126] As shown in Figures 15 and 16, when the thickness of the semi-transparent layer 131 becomes thicker, the transmission component to the resonance cavity becomes smaller. However, the case where Nb is used in the semi-transparent layer 131 is different from the case where Al is used. The reflection component on the surface of the metal Nb, which originally has a low reflectivity, becomes the main component, and the wavelength selection performance is maximized near the thickness of 15nm.

[0127] It can be seen that the change in the thickness of the semi-transparent layer 131 can cause a change in the wavelength selection performance. In specific implementation, it is necessary to set an appropriate thickness of the semi-transparent layer 131 according to the specific structure of the wavelength selection reflection layer F, the materials and thickness of each film layer, etc. to maximize the wavelength selection performance.

[0128] In some embodiments, as shown in FIG. 4 , the wavelength selective reflection layer F may be covered on the inclined surface x1 of the Fresnel structure 121. Since the inclination angle of the inclined surface x1 of the Fresnel structure 121 is designed according to the incident angle of the incident projection light, and the connecting surface x2 serves to connect the inclined surface x1 and is not used to directly receive and reflect the projection light, the wavelength selective reflection layer F may be only covered on the inclined surface x1 of the Fresnel structure to reflect the projection light incident on the wavelength selective reflection layer F on the inclined surface x1 of the Fresnel structure 121. When the projection light or the ambient light is incident on the connecting surface x2 of the Fresnel structure 121, since the wavelength selective reflection layer F is not provided on the surface, the incident light may be directly transmitted to avoid the reflection of this part of the light and interference with the projection light.

[0129] FIG. 17 is a second schematic diagram of the structure of the projection screen provided in an embodiment of the present application.

[0130] In some embodiments, as shown in Fig. 17, the wavelength selective reflection layer F may cover the inclined surface x1 and the connecting surface x2 of the Fresnel structure 121. Through research and testing, it is found that the wavelength selective reflection of the wavelength selective reflection layer F changes when responding to light with different incident angles.

[0131] FIG18 is a comparison diagram of reflectivity curves of light at different incident angles provided in an embodiment of the present application. FIG18 shows reflectivity curves of light at different wavelengths when the incident angles incident on the wavelength selective reflection layer are 0°, 30°, and 60°, respectively.

[0132] It can be seen from Figure 18 that when the incident angle when incident on the wavelength selective reflection layer changes, the wavelength selectively reflected by the wavelength selective reflection layer moves toward the short wavelength side, and the Fresnel structure in the projection screen is designed for the incident angle of the projection light. The ambient light incident on the projection screen comes from all directions. After being diffused by the diffusion layer 11, it will be incident on the wavelength selective reflection layer F at a variety of incident angles. This part of the light usually undergoes multiple reflections on the surface of the wavelength selective reflection layer, and the reflection process is accompanied by a continuous change in the incident angle. Then, according to the dependence of the wavelength selective reflection layer on the incident angle, the ambient light can be made to achieve full-band attenuation in the visible light range after multiple reflections by the wavelength selective reflection layer. Then, the energy proportion of the projection light in the light reflected by the projection screen is greatly increased, and the contrast is improved.

[0133] FIG. 19 is a third schematic diagram of the structure of the projection screen provided in an embodiment of the present application.

[0134] Taking the projection screen structure shown in FIG. 19 as an example, the tilt angle of the inclined surface x1 of the Fresnel structure 121 is 15°, and the connecting surface x2 is set perpendicular to the plane where the projection screen is located. After the ambient light C with an incident angle of 45° is incident on the outermost diffusion layer 11 of the projection screen, the refraction angle is 25°, and the incident angle of the wavelength selective reflection layer F is 65°. The ambient light firstly enters the wavelength selective reflection layer on the surface of the connecting surface x2, is reflected by the wavelength selective reflection layer on the surface of the connecting surface x2, and then enters the wavelength selective reflection layer on the surface of the inclined surface x1. In other words, the ambient light will be reflected twice by the wavelength selective reflection layer, and the incident angles of the two incidents on the wavelength selective reflection layer are 65° and 10° respectively.

[0135] Figure 20 is a reflectivity curve of the wavelength selective reflection layer provided in an embodiment of the present application for light with an incident angle of 65°, Figure 21 is a reflectivity curve of the wavelength selective reflection layer provided in an embodiment of the present application for light with an incident angle of 10°, and Figure 22 is a reflectivity curve of the wavelength selective reflection layer provided in an embodiment of the present application after two reflections.

[0136] As shown in Figures 20 and 21, the positions of the wavelengths selectively reflected by the wavelength selective reflection layer for light with incident angles of 65° and 10° are not the same. After superimposing the two reflectivity curves with incident angles of 65° and 10°, a reflectivity curve as shown in Figure 22 can be obtained. It can be seen from Figure 22 that after the ambient light is incident on the wavelength selective reflection layer at 65° and reflected by the wavelength selective reflection layer, it is incident on the wavelength selective reflection layer at 10° and reflected again by the wavelength selective reflection layer. The final effect is that the reflectivity of the entire visible light band is reduced. Therefore, when the ambient light brightness is strong, the intensity of the ambient light finally emitted from the projection screen is greatly reduced after being reflected by the projection screen.

[0137] FIG. 23 is a relative intensity curve of the ambient light provided in an embodiment of the present application when it is incident on the projection screen, and FIG. 24 is a relative intensity curve of the ambient light provided in an embodiment of the present application after being reflected by the projection screen.

[0138] Comparing FIG. 23 and FIG. 24, it can be seen that when the ambient light is incident on the projection screen at the incident angle shown in FIG. 19, it has a high intensity in the visible light band, and after two reflections by the wavelength selective reflection layer, the intensity in the full band of visible light is reduced. The ambient light comes from all directions, so it can be incident on the projection screen at various angles. After the diffusion effect of the diffusion layer 11 in the projection screen, the angle of incidence on the wavelength selective reflection layer can be diversified. Then, after multiple reflections by the wavelength selective reflection layer, the reflectivity of the incident ambient light in the full band of visible light can be greatly reduced, thereby attenuating the reflection of the ambient light by the projection screen, thereby improving the contrast of the projection light.

[0139] The present application also provides several deformation structures of the projection screen. Figure 25 is a fourth structural schematic diagram of the projection screen provided in the present application.

[0140] As shown in Fig. 4 and Fig. 25, the projection screen further includes: an adhesive layer 14, which is located between the diffusion layer 11 and the Fresnel structure layer 12 and is used to bond the diffusion layer 11 to the Fresnel structure layer 12. The adhesive layer 14 can be made of an adhesive material such as epoxy resin, acrylic resin, silicone, etc., which is not limited here.

[0141] In some embodiments, as shown in FIG4 , the Fresnel structure 121 of the Fresnel structure layer 12 is located on a side away from the adhesive layer 14; the adhesive layer 14 is used to bond the diffusion layer 11 to the surface of the Fresnel structure layer 12 on the side away from the Fresnel structure 121. When the Fresnel structure is disposed on the side away from the adhesive layer 14, the semi-transmissive layer in the wavelength selective reflection layer F needs to be disposed on the side close to the Fresnel structure 121.

[0142] In some embodiments, as shown in FIG25 , the Fresnel structure 121 of the Fresnel structure layer 12 is located on the side facing the adhesive layer 14; the adhesive layer 14 is used to bond the diffusion layer 11 and the wavelength selective reflection layer F on the Fresnel structure 121. When the Fresnel structure is arranged on the side close to the adhesive layer 14, the semi-transmissive layer in the wavelength selective reflection layer F needs to be arranged on the side away from the Fresnel structure 121. The arrangement order of the film layers in the wavelength selective reflection layer F in FIG4 and FIG25 is opposite.

[0143] When the Fresnel structure is arranged on the side close to the adhesive layer 14, the adhesive layer 14 can play a role in protecting the wavelength selective reflection layer F. Since the Fresnel structure layer 12 is located on the side farthest from the audience and no light is incident on the Fresnel structure layer 12, the requirements on the light transmittance and damage specifications of the Fresnel structure layer 12 are reduced. It is no longer necessary to use expensive optical materials to make the Fresnel structure layer 12, and cheaper industrial materials can be used for production, thereby reducing production costs.

[0144] FIG. 26 is a fifth schematic diagram of the structure of the projection screen provided in an embodiment of the present application.

[0145] In some embodiments, as shown in FIG. 26 , the diffusion layer 11 includes: a second substrate 111 and a diffusion material 112 .

[0146] The second substrate 111 is used as a substrate for providing the diffusion material 112 . The second substrate 111 is in contact with the adhesive layer 14 . The diffusion material 112 is located on a surface of the second substrate 111 that is away from the adhesive layer 14 .

[0147] The current projection system usually uses a laser light source. The laser has a high collimation, so the divergence angle of the projection light is small. The light reflected by the projection screen has a high collimation, which also leads to a small viewing angle. By setting the diffusion layer 11, the emission angle of the light after passing through the diffusion layer can be diversified, so that the light finally emitted by the projection screen has a certain divergence angle, which increases the viewing angle of the audience watching the projected image. In addition, the diffusion layer 11 is also conducive to reducing laser speckle and optimizing the projection image.

[0148] The diffusion material 112 may be a resin material or an inorganic material containing diffusion particles, and the diffusion particles may be, but are not limited to, silicon dioxide particles, aluminum oxide particles, titanium oxide particles, cerium oxide particles, zirconium oxide particles, tantalum oxide particles, zinc oxide particles, magnesium fluoride particles, etc. The diffusion material 112 may be manufactured by various coating methods, which are not limited here.

[0149] The second substrate 111 can be made of, but not limited to, PET, polyethylene naphthalate (PEN), polycarbonate (PC), polymethyl methacrylate (PMMA), triacetylcellulose (TAC), cycloolefin polymer (COP), thermoplastic polyurethane (TPU), polyvinyl chloride (PVC), polyimide (PI), polyamide (PA), polyethylene (PE), polypropylene (PP), and the like.

[0150] FIG. 27 is a sixth schematic diagram of the structure of the projection screen provided in an embodiment of the present application.

[0151] In some embodiments, as shown in FIG. 27 , the diffusion layer 11 only includes a second substrate 111, and the second substrate 111 is in contact with the adhesive layer 14 and is bonded to the Fresnel structure layer 12 through the adhesive layer 14. The material of the second substrate 111 includes a diffusion material, so when the second substrate 111 is formed, the second substrate 111 can have a light diffusion ability and a certain haze. The second substrate 111 including the diffusion material can expand the field of view angle and reduce the reflection of light, thereby preventing the light from forming a clear image on the ceiling, having the effect of anti-ceiling reflection, and can enhance the viewing experience of the audience.

[0152] FIG. 28 is the seventh structural schematic diagram of the projection screen provided in the embodiment of the present application.

[0153] In some embodiments, as shown in FIG. 28 , the diffusion layer 11 includes only a second substrate 111, which is in contact with the adhesive layer 14 and is bonded to the Fresnel structure layer 12 through the adhesive layer 14. The surface of the second substrate 111 on the side away from the adhesive layer 14 is an uneven surface. The uneven surface can be formed by sandblasting or alkali treating the surface of the second substrate 111, which is not limited here. The uneven surface of the second substrate 111 can play a certain role in light diffusion and atomization, thereby expanding the viewing angle, resisting ceiling reflection, and the like.

[0154] FIG. 29 is an eighth schematic diagram of the structure of the projection screen provided in an embodiment of the present application.

[0155] In some embodiments, as shown in FIG29 , the adhesive layer 14 may contain a light absorbing material and color the adhesive layer 14 to improve the black brightness of the projection screen. In a specific implementation, the adhesive layer 14 may be colored with a dark material such as carbon black or dye to deepen the color of the adhesive layer 14, which is not limited here.

[0156] FIG. 30 is a ninth structural schematic diagram of the projection screen provided in an embodiment of the present application.

[0157] In some embodiments, as shown in FIG30 , the projection screen may also include only the Fresnel structure layer 12 and the diffusion layer 11. The Fresnel structure of the Fresnel structure layer 12 is arranged on the side facing the viewer, and the diffusion layer 11 is located on the surface of the wavelength selective reflection layer F away from the Fresnel structure layer 12. In this case, the diffusion layer adopts the diffusion material 112 covered on the wavelength selective reflection layer F. The diffusion material 112 can be formed on the surface of the wavelength selective reflection layer F by coating, spraying, etc. The projection screen structure shown in FIG30 can effectively reduce the thickness of the projection screen.

[0158] When the projection screen structure shown in FIG30 is used, the semi-transmissive layer in the wavelength selective reflection layer F needs to be arranged on the side away from the Fresnel structure 121. The arrangement order of the film layers in the wavelength selective reflection layer F in FIG4 and FIG30 is opposite.

[0159] In a specific implementation, as shown in FIG. 30 , the Fresnel structure layer 12 may include a third substrate 122 , wherein the surface of the third substrate 122 facing the diffusion layer 11 and the surface of the third substrate 122 away from the diffusion layer 11 are both flat surfaces, and the Fresnel structure 121 is located on the surface of one side of the third substrate 122 .

[0160] The third substrate 122 can be made of materials such as PET, which is not limited here. The Fresnel structure 121 can be made by using a mold having a Fresnel structure and a UV molding process using a UV curable resin. The Fresnel structure 121 can be formed by applying a UV curable resin to a mold having a Fresnel structure, and using the third substrate 122 to emboss and UV cure the UV curable resin.

[0161] FIG. 31 is a tenth schematic diagram of the structure of the projection screen provided in an embodiment of the present application.

[0162] In some embodiments, as shown in FIG31 , the Fresnel structure layer 12 may also be an integrated structure, where one surface of the Fresnel structure layer 12 is the Fresnel structure 121, and the surface opposite to the Fresnel structure 121 is a flat surface. The use of an integrated structure of the Fresnel structure layer can omit the process of combining the substrate with the Fresnel structure, further simplifying the manufacturing process.

[0163] In a specific implementation, the integrally formed Fresnel structure layer 12 can be manufactured by thermoforming, and the Fresnel structure layer can be made of thermoplastic material, which is not limited here.

[0164] It is worth noting that the projection screen structures shown in Figures 25 to 31 all use the wavelength selective reflection layer F covering the inclined surface of the Fresnel structure 121 as an example to illustrate the structure of other film layers. In specific implementation, on the premise of having the same other film layers, the wavelength selective reflection layer F can also cover the inclined surface and connecting surface of the Fresnel structure 121.

[0165] FIG. 32 is a third schematic diagram of the structure of a projection screen in the related art.

[0166] As shown in FIG32 , in the related art, the projection screen uses an evaporation or sputtering process to produce a reflective material layer 13, and the reflective material layer 13 produced using the current process usually covers the entire surface of the Fresnel structure, that is, the reflective material layer 13 covers both the inclined surface x1 of the Fresnel structure and the transition surface x2 of the Fresnel structure.

[0167] As shown in Figure 32, the ambient light C incident on the projection screen will not only be incident on the inclined surface x1, but also on the connecting surface x2. Some of the light will be reflected by the reflective material layer 13 on the surface of the connecting surface x2, and finally emitted from the projection screen to affect the contrast of the projection light.

[0168] In order to improve the contrast of the projection light, it is considered to remove the reflective material layer 13 on the surface of the connection surface x2 to avoid the reflection of part of the ambient light on the connection surface. Fig. 33 is a fourth structural schematic diagram of a projection screen in the related art.

[0169] As shown in Figure 33, when the reflective material layer 13 is not set on the surface of the connecting surface x2, the ambient light C that was originally reflected multiple times by the reflective material layer 13 on the surface of the connecting surface x2 can be directly emitted from the connecting surface x2. Then, this part of the ambient light that was originally reflected toward the audience side will no longer interfere with the projection light L, thereby improving the contrast of the projection light to a certain extent.

[0170] However, the reflective material layer on the surface of the Fresnel structure is usually prepared by a coating process. If you want to coat only part of the surface of the Fresnel structure, it is usually necessary to improve the coating equipment, which has the problems of difficult equipment adjustment and high cost.

[0171] In view of this, an embodiment of the present application provides a method for manufacturing a projection screen, which does not rely on coating equipment. By adjusting the coating conditions and the coating amount, the purpose of coating only on the inclined surface of the Fresnel structure and minimizing the coating amount on the connecting surface can be achieved.

[0172] Figure 34 is a flow chart of a method for manufacturing a projection screen provided in an embodiment of the present application.

[0173] As shown in FIG. 34 , the method for manufacturing a projection screen includes:

[0174] S10, making a Fresnel structure layer;

[0175] S20, forming a discontinuous first film on the inclined surface of the Fresnel structure, and forming a continuous second film layer on the first film;

[0176] S30, forming a surface functional layer on one side surface of the Fresnel structure layer with the reflective layer.

[0177] In the embodiment of the present application, the reflective layer can be formed of a single reflective material to form the reflective material layer, or the reflective layer can also be formed of the wavelength selective reflective layer with wavelength selective properties, which is not limited here. The reflective layer can still be made on the Fresnel structure layer by evaporation or sputtering. By adjusting the coating conditions and coating amount, the reflective layer can be formed on the inclined surface of the Fresnel structure, while the coating amount on the connecting surface is minimized.

[0178] Specifically, the Fresnel structure layer can be manufactured by a variety of methods. FIG35 is a schematic diagram of one manufacturing process of the Fresnel structure layer provided in an embodiment of the present application; FIG36 is a schematic diagram of a second manufacturing process of the Fresnel structure layer provided in an embodiment of the present application.

[0179] 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 using a substrate to emboss and UV-cure the ultraviolet curable resin. As shown in FIG35 , first, an ultraviolet curable resin f' is applied to the mold M having a Fresnel structure on the surface; a third substrate 122 is provided, and the ultraviolet curable resin f' on the mold M is embossed onto the third substrate 122 at a specified pressure, and ultraviolet rays are irradiated from one side of the third substrate 122 to cure the ultraviolet curable resin f'. The ultraviolet curable resin f' is tightly bonded to the third substrate 122 while being cured, so that the Fresnel shape of the mold M is transferred to the third substrate 122, and the Fresnel structure 121 can be formed on the surface of the third substrate 122.

[0180] The Fresnel structure layer formed by ultraviolet curing resin usually has a substrate and a Fresnel structure as separate structures. However, the Fresnel structure layer made by the thermoforming method is an integrated structure, which can omit the process of combining the substrate and the Fresnel structure. As shown in FIG36 , the Fresnel structure layer of the integrated molding structure uses thermoplastic materials such as TPU or PVC. First, a third substrate 122 having a thermoplastic material is provided, and the third substrate 122 is thermoformed using a heated mold M having a Fresnel structure, thereby forming a Fresnel structure layer having a Fresnel structure 121.

[0181] As shown in Figures 35 and 36, the surface of the prepared Fresnel structure layer has multiple Fresnel structures 121. According to different application scenarios and manufacturing processes, each Fresnel structure 121 can form a concentric circle structure that is arranged in sequence and expands radially; or, each Fresnel structure 121 is a linear structure that extends along the horizontal direction of the projection screen and is arranged perpendicular to the horizontal direction, which is not limited here.

[0182] In order to form a reflective layer only on the inclined surface x1 of the Fresnel structure and not on the connecting surface x2, the embodiment of the present application adjusts the coating conditions and the coating amount when manufacturing the reflective layer.

[0183] Specifically, the embodiment of the present application inserts a plurality of interruption gaps during the coating process, so that the coating time periods and the interruption gaps are performed alternately.

[0184] FIG. 37 is a coating thickness curve in the related art, and FIG. 38 is a coating thickness curve provided in an embodiment of the present application.

[0185] As shown in FIG. 37 , in the related art, the coating process is continuous, and eventually a continuous reflective material film is formed on both the inclined surface x1 and the connecting surface x2 of the Fresnel structure.

[0186] In the embodiment of the present application, as shown in FIG. 38 , a plurality of interruption gaps k2 are inserted in the coating process, so that the coating period k1 and the interruption gaps k2 are performed alternately in the entire coating process. By controlling the coating period k1 and the length of the interruption gaps k2 and the coating amount, a non-continuous first film layer can be first formed on the inclined surface x1 of the Fresnel structure, and then a continuous second film layer can be formed on the first film. In this way, a continuous film layer is formed only on the inclined surface x1 of the Fresnel structure, and the coating amount on the connecting surface x2 is minimized.

[0187] 39 to 42 are schematic diagrams of the structure of the reflective layer during the coating process provided in embodiments of the present application.

[0188] Specifically, the process from no film to continuous film during the coating process is "nucleation → nucleus fusion → island → island fusion → continuous film", where the state until the island fusion is called a discontinuous film. The above-mentioned morphology of the film is usually related to the film thickness, which depends largely on the coating time, and the coating time is related to the coating rate.

[0189] Based on the above principle, the embodiment of the present application inserts an interruption gap in the coating process to adjust the coating time and the coating rate, so as to first form a discontinuous first thin film on the inclined surface x1 of the Fresnel structure.

[0190] As shown in FIG39 , a sharp step t is formed at the junction of the inclined surface x1 and the connecting surface x2 of each Fresnel structure, so that when the coating amount is small, the surrounding incident atoms are suppressed, more atoms a1 are incident on the inclined surface x1, and only the local area near the step on the connecting surface x2 has atoms a1 incident.

[0191] As shown in FIG40 , after the coating period ends, the coating is interrupted for a period of time, and the incident atoms gradually become stable atomic nuclei b. Due to the existence of the step portion t, the atoms are inhibited from wrapping back to the connecting surface x2, thereby preferentially forming a discontinuous first film s1 on the inclined surface x1.

[0192] As shown in FIG. 41 , after the interruption period, the coating on the Fresnel structure continues. At this time, the incident atoms a2 will gradually accumulate around the previously formed atomic nuclei, making the area around the position with the first film s1 higher, so that the coating will be performed preferentially over other positions.

[0193] As shown in FIG. 42 , after accumulating multiple coating periods, the film continues to grow, causing the atomic nuclei preferentially formed on the inclined surface x1 to disappear, and become a continuous second film layer s2 on the entire inclined surface.

[0194] In specific implementation, the duration of the interruption gap k2 is longer than the duration of the coating period k1, and the longer the interruption gap k2 is, the better the effect is. Considering the actual operability, the duration of the interruption gap k2 can be 30s to 60s; the duration of the coating period can be 1s to 10s (for example, about 5s).

[0195] Thus, a reflective layer can be formed on the inclined surface of each Fresnel structure in the Fresnel structure layer. After the Fresnel structure layer with the reflective layer on the surface is obtained, a surface functional layer is formed on the other side surface of the Fresnel structure layer.

[0196] The surface functional layer is usually located on the outermost side of the projection screen. In the embodiment of the present application, the surface functional layer can be processed differently according to different needs to achieve the effects of expanding the viewing angle, resisting ambient light reflection, resisting ceiling reflection, etc. The method for making the surface functional layer may include bonding, spraying, etching, etc., which is selected according to the type of the surface functional layer and is not limited here.

[0197] In some embodiments, the reflective layer may be the wavelength selective reflective layer F in the above embodiment, and the surface functional layer may be the diffusion layer 11 in the above embodiment.

[0198] When the reflective layer adopts the wavelength selective reflective layer F, the wavelength selective reflective layer includes a semi-transparent layer 131, a transparent medium layer 133 and a reflective layer 132 which are stacked. In order to form the wavelength selective reflective layer only on the inclined surface x1 of the Fresnel structure, any film layer in the wavelength selective reflective layer (the semi-transparent layer 131, the transparent medium layer 133 and the reflective layer 132) can be manufactured by the above-mentioned discontinuous coating process. The film layers manufactured by the discontinuous coating process will first form a discontinuous first film, and then form a continuous second film layer on the first film. The first film and the second film layer can be made of the same material or different materials as needed. When the first film and the second film layer are made of the same material, the film layer finally formed will not have a clear boundary, but only form a continuous film layer on the inclined surface of the Fresnel structure.

[0199] For example, when the reflective layer 132 in the wavelength selective reflective layer is manufactured by the above-mentioned discontinuous coating process, the discontinuous film is generally 1nm to 10nm in terms of film thickness, and the thickness of the reflective layer 132 when the first film s1 is formed is 1nm to 10nm. The second film layer needs to have good light reflection properties. In the embodiment of the present application, the thickness of the second film layer s2 in the reflective layer 132 is 50nm to 200nm. The thickness of the second film layer s2 is usually controlled to be less than 500nm to avoid the reflective layer being too thick.

[0200] The first film s1 is formed to make the subsequent coating grow preferentially on the inclined surface, and the first film s1 is a thin discontinuous film with no reflectivity, so the first film s1 can be made of metal material or transparent dielectric material. The metal material can be Ag or Al, and the transparent dielectric material can be Al2O3, Nb2O5, TiO2, ITO, SiO2, etc., which are not limited here.

[0201] The second film layer s2 on the first film s1 is used to reflect the projection light, and thus can be made of a metal material with a reflective property, such as Ag or Al, which is not limited here.

[0202] Similarly, the semi-transparent layer 131 and the transparent medium layer 133 in the wavelength selective reflection layer F can also be manufactured by the above-mentioned discontinuous coating process, so that the coating can be performed only on the inclined surface x1 of the Fresnel structure, and the coating amount on the connecting surface x2 is minimized.

[0203] It is worth noting that, since the light-transmitting medium layer in the wavelength-selective reflection layer F is made of light-transmitting material, the light-transmitting film layers formed on the inclined surface x1 and the connecting surface x2 of the Fresnel structure only have light-transmitting properties, so even if these light-transmitting film layers are formed on the connecting surface x2, they will not interfere with the light, so these completely light-transmitting film layers can also be made using traditional coating processes, which are not limited here. Usually, in order to save material costs, a discontinuous coating process is used in the implementation.

[0204] Furthermore, in some specific implementations, the semi-transparent layer 131 is first formed on the Fresnel structure, and then the transparent medium layer 133 and the reflective layer 132 are sequentially formed on the semi-transparent layer 131. Then, the semi-transparent layer 131 can be made by a discontinuous coating process, and the transparent medium layer 133 and the reflective layer 132 can be made by a discontinuous coating process in sequence; or, since the semi-transparent layer 131 can transmit most of the light beam and reflect a small part of the light beam, the semi-transparent layer 131 can also be made by a traditional overall coating process, and the transparent medium layer 133 and the reflective layer 132 can be made by a discontinuous coating process in sequence.

[0205] For a structure in which the reflective layer is made only of reflective materials, the reflective layer can also be made using a discontinuous coating process. Specifically, a first film s1 of 1nm to 10nm can be formed on the inclined surface x1 of the Fresnel structure, and then a second film layer s2 of 50nm to 200nm can be formed on the first film s1.

[0206] Based on the same inventive concept, the embodiment of the present application also provides a projection screen manufactured by the above manufacturing method. FIG43 is a structural schematic diagram of the projection screen provided by the embodiment of the present application.

[0207] As shown in FIG. 43 , the projection screen includes: a surface functional layer 11 ′, a Fresnel structure layer 12 and a reflective layer 13 ′.

[0208] The surface functional layer 11' is located on the outermost side of the projection screen. In the embodiment of the present application, the surface functional layer 11' is located on the side closest to the audience, which plays a role in protecting the projection screen. In addition, the surface functional layer 11' can also be processed by various means according to different needs to achieve the effects of expanding the viewing angle, resisting ambient light reflection, resisting ceiling reflection, etc. In some embodiments, the surface functional layer 11' can adopt the above-mentioned diffusion layer 11.

[0209] The Fresnel structure layer 12 is located on one side of the surface functional layer 11', specifically on the side of the surface functional layer 11' away from the audience. A plurality of Fresnel structures 121 arranged according to a set rule are arranged on the surface of one side of the Fresnel structure layer 12, and the Fresnel structure 121 includes an inclined surface x1 and a connecting surface x2 connected to each other.

[0210] The reflective layer 13' is located on the inclined surface x1 of each Fresnel structure 121. The reflective layer 13' in the embodiment of the present application is made by a coating process such as evaporation or sputtering, and the equipment used is a mature evaporation equipment or sputtering equipment in the relevant technology, and there is no need to improve the coating equipment. It is only necessary to adjust the coating conditions and the coating amount to form a reflective layer on the inclined surface of the Fresnel structure by using a discontinuous coating process, and the coating amount of the connecting surface is minimized, thereby avoiding the problem of difficult equipment adjustment and high cost.

[0211] In some embodiments, the reflective layer 13 ′ may be a reflective material layer 13 in the related art.

[0212] In some embodiments, the light reflecting layer 13 ′ may be the wavelength selective reflection layer F in the above embodiments.

[0213] Any film layer in the reflective layer 13' can be manufactured by a discontinuous film process. During the manufacturing process, a discontinuous first film s1 located on the inclined surface of the Fresnel structure and a second film layer s2 located on the first film s1 are formed.

[0214] The projection screen provided in the embodiment of the present application is only provided with a reflective layer on the inclined surface of the Fresnel structure, so the ambient light incident on the connecting surface can be directly emitted from the connecting surface, and this part of the ambient light that would originally be reflected toward the audience side will no longer interfere with the projection light, thereby improving the contrast of the projection light to a certain extent.

[0215] FIG. 44 is a twelfth schematic diagram of the structure of the projection screen provided in an embodiment of the present application.

[0216] As shown in FIG44 , a light absorbing layer 15 may be provided on the side of the Fresnel structure layer 12 away from the surface functional layer 11 ′, and the light absorbing layer may absorb the light emitted from the connection surface x2 of the Fresnel structure to prevent this part of the light from being re-incident into the projection screen after reflection or the like. The light absorbing layer 15 may be realized by doping the film layer with a light absorbing material, for example, carbon black or dye may be added to the film layer material to color the film layer so that it has the function of absorbing light, which is not limited here.

[0217] The projection screen provided in the embodiment of the present application may further include an adhesive layer. The setting position of the adhesive layer and the deformation structure of the projection screen can refer to the above embodiment and will not be described again here.

[0218] The embodiment of the present application further provides a projection system. As shown in FIG. 1 , the projection system includes: a projection device 2 and a projection screen 1 located at the light emitting side of the projection device 2 .

[0219] Figure 45 is a schematic diagram of the structure of the projection device provided in an embodiment of the present application.

[0220] As shown in FIG45 , the projection device includes: a light source device 21, an illumination light path 22, a light modulation component 23, and a projection lens 24. The illumination light path 22 is located at the light exit side of the light source device 21, the light modulation component 23 is located at the light exit side of the illumination light path 22, and the projection lens 24 is located at the light exit side of the light modulation component 23.

[0221] 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 lasers of multiple colors or multiple lasers that emit lasers of different colors. When the laser light source device adopts a monochromatic laser, the laser display device also needs to be provided with a color wheel, which is used for color conversion. The monochromatic laser cooperates with the color wheel to achieve the purpose of emitting primary color lights of different colors in sequence. When the laser light source device adopts a laser that can emit lasers of multiple colors, it is necessary to control the laser light source to emit lasers of different colors as primary color lights in sequence.

[0222] In the embodiment of the present application, the light source device may adopt a three-color laser light source device, which may be a laser that emits three primary color lasers, such as an MCL laser, etc.; it may also include a red laser, a green laser, and a blue laser that emit three primary color lasers respectively. The use of a three-color laser light source device is conducive to improving the color gamut of the projected image, has better color expression, and can accurately reproduce the input image.

[0223] The illumination optical path 22 is located at the light output side of the light source device 21. The illumination optical path 22 collimates the output light of the light source device 21 and allows the output light of the light source device 21 to be incident on the light modulation component 23 at a suitable angle. The illumination optical path 22 may include multiple lenses or lens groups, which are not limited here.

[0224] The light modulator 23 is used to modulate the incident light. In a specific implementation, the light modulator 23 can be a digital micromirror (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 many tiny reflectors, each of which can be driven to deflect individually. By controlling the deflection angle of the DMD, the brightness of the light incident on the projection lens 24 is controlled.

[0225] The projection lens 24 is used to image the output light of the light modulation component 23 , and the image is projected after being imaged by the projection lens 24 .

[0226] In the embodiment of the present application, the projection device 2 can use an ultra-short-throw projection device, that is, the projection lens 24 in the projection device uses an ultra-short-throw projection lens. The use of an ultra-short-throw projection device can greatly shorten the distance between the projection device 2 and the projection screen 1, and can achieve large-size image display while shortening the projection distance.

[0227] The projection screen 1 is located at the light-emitting side of the projection lens in the projection device. The projection screen 1 includes a diffusion layer, a Fresnel structure layer, and a wavelength selective reflection layer located on at least a part of the surface of the Fresnel structure of the Fresnel structure layer. The wavelength selective reflection layer can selectively reflect the projection light emitted by the projection device, and the reflectivity of the light in other bands is greatly reduced. When the projection device is turned off, a black appearance can be achieved, and when the projection device is turned on, a bright display can be obtained, thereby significantly improving the contrast of the projected image.

[0228] Although the preferred embodiments of the present application have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0229] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

A projection screen, comprising: Diffusion layer; A Fresnel structure layer is located on one side of the diffusion layer; one side surface of the Fresnel structure layer has a Fresnel structure; and a wavelength selective reflection layer covers at least a portion of the surface of the Fresnel structure of the Fresnel structure layer; the reflectivity of the wavelength selective reflection layer for the projection light emitted by the projection device is greater than the reflectivity of light in other wavelength bands. The projection screen as claimed in claim 1, wherein The Fresnel structure comprises: an inclined surface and a connecting surface connected to each other; the inclined surface is inclined relative to the plane where the diffusion layer is located, and the inclination angle of the inclined surface satisfies the requirement of reflecting the projection light of the wavelength selective reflection layer incident on the surface of the inclined surface toward the audience; the wavelength selective reflection layer covers the surface of the inclined surface of the Fresnel structure. The projection screen as claimed in claim 1, wherein The Fresnel structure comprises: an inclined surface and a connecting surface connected to each other; the inclined surface is inclined relative to the plane where the diffusion layer is located, and the inclination angle of the inclined surface satisfies the requirement of reflecting the projection light of the wavelength selective reflection layer incident on the surface of the inclined surface toward the audience; the wavelength selective reflection layer covers the surface of the inclined surface and the connecting surface of the Fresnel structure. The projection screen according to any one of claims 1 to 3, wherein: The wavelength selective reflection layer includes: a semi-transparent layer, located on a side close to the diffusion layer; a reflection layer, located on a side of the semi-transparent layer away from the diffusion layer; and a transparent medium layer, located between the semi-transparent layer and the reflection layer; wherein the product of the refractive index and the thickness of the transparent medium layer satisfies the condition for causing the projection light emitted by the projection device to resonate. The projection screen as claimed in claim 4, wherein The semi-transparent layer adopts a laminated structure formed by at least one metal selected from aluminum, niobium, silver and titanium; the thickness of the semi-transparent layer is 2nm-20nm. The projection screen as claimed in claim 4, wherein The material of the reflective layer is aluminum, aluminum alloy, silver or silver alloy; the thickness of the reflective layer is greater than 50nm and less than 100nm. The projection screen as claimed in claim 4, wherein The material of the light-transmitting medium layer is metal oxide, nitride or transparent resin. The projection screen as claimed in claim 7, wherein: The material of the light-transmitting medium layer is at least one of TiO2, Nb2O5, ZrO2, Al2O3, ZnO2, and SiO2. The projection screen as claimed in claim 7, wherein: The product of the thickness of the light-transmitting medium layer and the refractive index is 1200-1400, which is sufficient to make the wavelength-selective reflection layer reflect the red laser, green laser and blue laser emitted by the projection device at the same time. The projection screen of claim 9, wherein: The central wavelength of the light reflected by the wavelength selective reflection layer fluctuates within a range of 5 nm to 20 nm. The projection screen of claim 10, wherein: The central wavelength of the red laser reflected by the wavelength selective reflection layer is 635nm, 650nm or 643nm; the central wavelength of the green laser reflected by the wavelength selective reflection layer is 520nm, 525nm or 532nm; the central wavelength of the blue laser reflected by the wavelength selective reflection layer is 445nm or 465nm. The projection screen according to any one of claims 4 to 11, wherein: The wavelength selective reflection layer further includes: a first substrate located on a side of the semi-transparent layer away from the transparent medium layer. The projection screen according to any one of claims 1 to 12, further comprising: an adhesive layer, located between the diffusion layer and the Fresnel structure layer; the Fresnel structure of the Fresnel structure layer is located on a side away from the adhesive layer; The adhesive layer is used to bond the diffusion layer and the surface of the Fresnel structure layer on the opposite side to the Fresnel structure; alternatively, the Fresnel structure of the Fresnel structure layer is located on the side facing the adhesive layer; the adhesive layer is used to bond the diffusion layer and the wavelength selective reflection layer on the Fresnel structure; wherein the adhesive layer contains a light absorbing material. The projection screen according to any one of claims 1 to 12, wherein: The Fresnel structure of the Fresnel structure layer is located on the side facing the audience; the diffusion layer is located on the surface of the wavelength selective reflection layer away from the Fresnel structure layer; and the diffusion layer is a diffusion material covering the wavelength selective reflection layer. The projection screen according to any one of claims 1 to 14, wherein: The Fresnel structure layer comprises: a third substrate, a surface of the third substrate facing the diffusion layer and a surface of the third substrate away from the diffusion layer are both flat surfaces; the Fresnel structure is located on the surface of the third substrate; or, the Fresnel structure layer is an integrated structure, a surface of one side of the Fresnel structure layer is the Fresnel structure, and a surface of the Fresnel structure layer opposite to the Fresnel structure is a flat surface. A method for manufacturing a projection screen, comprising: Fresnel structure manufacturing process: manufacturing Fresnel structure layer; One side surface of the Fresnel structure layer has a plurality of Fresnel structures, and the Fresnel structure includes mutually connected inclined surfaces and connecting surfaces; a reflective layer manufacturing process: forming a discontinuous first film on the inclined surface of the Fresnel structure, and forming a continuous second film layer on the first film; a surface functional layer manufacturing process: forming a surface functional layer on one side surface of the Fresnel structure layer with the reflective layer. The method of claim 16, wherein: The reflective layer manufacturing process adopts evaporation or sputtering technology; the reflective layer manufacturing process includes: inserting multiple interruption gaps in the coating process, so that the coating period and the interruption gaps are alternated; wherein, the duration of the interruption gap is greater than the duration of the coating period; the duration of the interruption gap is 30s to 60s; the duration of the coating period is 1s to 10s. The production method according to claim 16 or 17, wherein The reflective layer is a wavelength selective reflective layer; the wavelength selective reflective layer includes: a semi-transparent layer, located on a side close to the surface functional layer; a reflective layer, located on a side of the semi-transparent layer away from the surface functional layer; and a transparent medium layer, located between the semi-transparent layer and the reflective layer; wherein the product of the refractive index and the thickness of the transparent medium layer satisfies the condition for causing the projection light emitted by the projection device to resonate; any film layer in the wavelength selective reflective layer is manufactured using the reflective layer manufacturing process. The method of claim 18, wherein: The first film in the reflective layer is made of metal material or transparent dielectric material; the second film layer in the reflective layer is made of metal material; the thickness of the first film is 1nm to 10nm; the thickness of the second film layer is 50nm to 200nm. A projection system, comprising: A projection device, used for emitting projection light; and a projection screen, located on the light-emitting side of the projection device, the projection screen being the projection screen according to any one of claims 1 to 15; 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 light modulation component, located on the light-emitting side of the three-color laser light source device, for modulating the emitted lasers of the three-color laser light source device; and a projection lens, located on the light-emitting side of the light modulation component.

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