Projection screen and projection system

Abstract

The utility model discloses a projection screen and a projection system. The projection screen comprises a Fresnel lens layer, reflecting layers located on the surfaces of all lens units of the Fresnel lens layer, and a first light-transmitting medium layer and a second light-transmitting medium layer which are located on the side, away from the reflecting layers, of the Fresnel lens layer. Wherein the refractive index of the first light-transmitting dielectric layer is larger than that of the second light-transmitting dielectric layer, and the difference between the refractive indexes of the first light-transmitting dielectric layer and the second light-transmitting dielectric layer meets the condition that projection light rays incident to the projection screen are reflected by the reflecting layer, then are incident to the first light-transmitting dielectric layer, are transmitted by the first light-transmitting dielectric layer and the second light-transmitting dielectric layer and then are emitted; and the ambient light incident to the projection screen is reflected by the reflecting layer, then is incident to the first light-transmitting medium layer and is totally reflected on the interface of the first light-transmitting medium layer and the second light-transmitting medium layer, so that the emission of the ambient light can be reduced, and the contrast ratio of the projection light is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of projection, in particular to a projection screen and a projection system. Background Art

[0002] As display products continue to grow in size, the market for projection display products, as a large-screen alternative to LCD and OLED TVs, is rapidly expanding, driven by power consumption, weight, and size considerations. Laser TVs, which utilize ultra-short-throw projection equipment, are experiencing rapid growth due to their high image quality and large screen size.

[0003] Current projection systems are typically used in conjunction with a reflective projection screen. Light from the projector is emitted by the projector and then reflected back toward the viewer. However, the projection screen not only reflects the light from the projector but also reflects some ambient light towards the viewer, resulting in a decrease in the contrast of the projected image. Utility Model Content

[0004] According to a first aspect of an embodiment of the present invention, a projection screen is provided, comprising:

[0005] Fresnel lens layer; the Fresnel lens layer includes a plurality of lens units, each lens unit includes a lens surface and a non-lens surface; the lens surface is tilted relative to the plane where the projection screen is located;

[0006] a reflective layer, covering at least the lens surface of each lens unit;

[0007] A first light-transmitting medium layer is located on the side of the Fresnel lens layer facing the audience; and

[0008] a second light-transmitting medium layer, located on a side of the first light-transmitting medium layer away from the Fresnel lens layer;

[0009] Among them, the refractive index of the second light-transmitting medium layer is smaller than the refractive index of the first light-transmitting medium layer, and the difference in refractive index between the first light-transmitting medium layer and the second light-transmitting medium layer satisfies: the projection light incident on the projection screen is reflected by the reflective layer and then incident on the first light-transmitting medium layer, and is transmitted by the first light-transmitting medium layer and the second light-transmitting medium layer and then emitted; the ambient light incident on the projection screen is reflected by the reflective layer and then incident on the first light-transmitting medium layer, and is totally reflected at the interface between the first light-transmitting medium layer and the second light-transmitting medium layer.

[0010] In some embodiments of the present utility model, an absorbent material is mixed in the first light-transmitting medium layer.

[0011] In some embodiments of the present utility model, the difference between the refractive index of the first light-transmitting medium layer and the refractive index of the second light-transmitting medium layer is greater than or equal to 0.2 and less than or equal to 0.8.

[0012] In some embodiments of the present utility model, the refractive index of the second light-transmitting medium layer is 1.28 to 1.40.

[0013] In some embodiments of the present utility model, the surface of the second light-transmitting medium layer facing away from the first light-transmitting medium layer is a rough surface.

[0014] In some embodiments of the present utility model, the projection screen further includes:

[0015] A diffusion layer located on the surface of the second light-transmitting medium layer facing away from the first light-transmitting medium layer.

[0016] In some embodiments of the present utility model, the diffusion layer is a diffusion material located on the surface of the second light-transmitting medium layer;

[0017] Or, the diffusion layer includes a first substrate and a diffusion material located on one surface of the first substrate.

[0018] In some embodiments of the present utility model, the Fresnel lens layer includes: a second substrate and a plurality of lens units located on one surface of the second substrate; or, the Fresnel lens layer is an integral structure, one surface of the Fresnel lens layer is a plane, and the surface opposite to the plane includes a plurality of lens units;

[0019] Each of the lens units is located on the side facing away from the first light-transmitting medium layer; or, each lens unit is located on the side facing the first light-transmitting medium layer.

[0020] In some embodiments of the present utility model, the reflectivity of the reflection layer to the projection light emitted by the projection device is greater than the reflectivity to light of other wavelengths.

[0021] In a second aspect of the embodiments of the present utility model, a projection system is provided, including:

[0022] A projection device for emitting projection light; and

[0023] A projection screen located on the light-emitting side of the projection device, the projection screen being any of the above projection screens;

[0024] Wherein, the projection device is an ultra-short throw laser projection device; the projection device includes:

[0025] A three-color laser light source device for emitting three-primary-color lasers;

[0026] A display element is located on the light-emitting side of the three-color laser light source device and is used to modulate the laser light emitted by the three-color laser light source device to form a display image; and

[0027] The lens is located on the light-emitting side of the display element and projects the light emitted by the display element into an image.

[0028] The projection screen and projection system provided by the embodiments of the present invention include a Fresnel lens layer, a reflective layer located on the surface of each lens unit of the Fresnel lens layer, and a first light-transmitting medium layer and a second light-transmitting medium layer located on the side of the Fresnel lens layer facing away from the reflective layer. The refractive index of the first light-transmitting medium layer is greater than the refractive index of the second medium layer, and the difference in refractive index between the first light-transmitting medium layer and the second light-transmitting medium layer satisfies the following conditions: projection light incident on the projection screen is reflected by the reflective layer, then incident on the first light-transmitting medium layer, and then transmitted by the first light-transmitting medium layer and the second light-transmitting medium layer before exiting; while ambient light incident on the projection screen is reflected by the reflective layer, then incident on the first light-transmitting medium layer, and is totally reflected at the interface between the first light-transmitting medium layer and the second light-transmitting medium layer, thereby reducing the exit of ambient light and improving the contrast of the projection light. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments of the present invention. Obviously, the drawings introduced below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0030] Figure 1 A schematic diagram of the structure of a projection system provided by an embodiment of the present utility model;

[0031] Figure 2 This is one of the structural schematic diagrams of the projection screen provided by an embodiment of the present utility model;

[0032] Figure 3 A schematic diagram of the planar structure of a Fresnel lens layer provided in an embodiment of the present utility model;

[0033] Figure 4 The second structural diagram of the projection screen provided by the embodiment of the utility model;

[0034] Figure 5 One of the schematic diagrams of the refraction principle provided in the embodiment of the utility model;

[0035] Figure 6 The second schematic diagram of the refraction principle provided by the embodiment of the utility model;

[0036] Figure 7 Schematic diagram of the total reflection principle provided by an embodiment of the present utility model;

[0037] Figure 8 The third structural schematic diagram of the projection screen provided by an embodiment of the present utility model;

[0038] Figure 9 The fourth structural schematic diagram of the projection screen provided by an embodiment of the present utility model;

[0039] Figure 10 The fifth structural schematic diagram of the projection screen provided by an embodiment of the present utility model;

[0040] Figure 11 The sixth structural schematic diagram of the projection screen provided by an embodiment of the present utility model;

[0041] Figure 12 The seventh structural schematic diagram of the projection screen provided by an embodiment of the present utility model;

[0042] Figure 13 The eighth structural schematic diagram of the projection screen provided by an embodiment of the present utility model;

[0043] Figure 14 Schematic diagram of the structure of the reflective layer provided by an embodiment of the present utility model;

[0044] Figure 15 Schematic diagram of the structure of the projection device provided by an embodiment of the present utility model. Detailed implementation manners

[0045] To make the above objects, features, and advantages of the present utility model more obvious and understandable, the present utility model will be further described below in conjunction with the drawings and embodiments. However, the exemplary embodiments can be implemented in various forms and should not be construed as limited to the embodiments described herein; on the contrary, these embodiments are provided to make the present utility model more comprehensive and complete, and to fully convey the concept of the exemplary embodiments to those skilled in the art. The same reference numerals in the drawings represent the same or similar structures, so the repeated description thereof will be omitted. The words expressing positions and directions described in the present utility model are all illustrated with reference to the drawings, but can be changed according to needs, and all changes made are included in the protection scope of the present utility model. The drawings of the present utility model are only used to illustrate the relative position relationship and do not represent the true proportion.

[0046] With the popularization of laser display products, as a large-screen product replacing LCD TVs and OLED TVs, the market for laser TVs has expanded rapidly. To achieve better brightness and display effects, projection devices generally use projection screens in combination.

[0047] As Figure 1 shown, the projection system includes: a projection device 2 and a projection screen 1.

[0048] The projection screen 1 is located on the light-emitting side of the projection device 2, and the audience faces the projection screen 1. The projection device 2 emits projection light, and the projection light is incident on the projection screen 1 and then exits in the direction of the audience through the projection screen 1, so that the audience can view the projection image.

[0049] When the projection device 2 and the audience are on the same side of the projection screen 1, this projection system is called a front-projection system; when the projection device 2 and the audience are on opposite sides of the projection screen 1, this projection system is called a rear-projection system. In the front-projection system, the projection device 2 emits projection light towards the projection screen 1, and the projection screen 1 reflects the projection light towards the audience, so that the audience can view the projection image. In the rear-projection system, the projection device 2 emits projection light towards the projection screen 1, and the projection light passes through the projection screen 1 and exits towards the audience, so that the audience can view the projection image.

[0050] In the embodiments of the present utility model, the structure of the projection screen is specifically described by taking a ultra-short-throw projection system as an example. The projection screen 1 can be installed on a wall or hung high, or can be integrated with the projection device into a display device. In the use state, the projection device 2 can be located below the projection screen 1 and emit projection light obliquely upward from below the projection screen 1 to the projection screen 1; or, the projection device 2 can be located above the projection screen 1 and emit projection light obliquely downward from above the projection screen 1 to the projection screen 1. Since the ultra-short-throw projection system has a small projection ratio, a large-sized projection image can be obtained while reducing the distance between the projection device 2 and the projection screen 1, which is very suitable for applications such as laser TVs.

[0051] As Figure 1 shown, the projection screen 1 is usually rectangular in shape. When in use, the bottom side and the top side of it are usually parallel to the horizontal direction x, and the two side sides are parallel to the vertical direction y, and the horizontal direction x and the vertical direction y are perpendicular to each other. In the embodiments of the present utility model, an example is schematically shown with the projection device 2 arranged at a position close to the bottom side of the projection screen 1.

[0052] Figure 2 For a projection screen used in cooperation with a front-projection system, as Figure 2 shown, the projection screen includes: a surface layer 10, a Fresnel lens layer 12, and a reflection layer 13.

[0053] The surface layer 10 can be located on the outermost surface of the projection screen. In some embodiments, the surface layer 10 is located on the side closest to the audience, and functions to protect the projection screen, etc.

[0054] AsFigure 2 and Figure 3 As shown, the Fresnel lens layer 12 is located on the side of the surface layer 10 away from the audience. The Fresnel lens layer 12 includes a plurality of lens units 121 arranged according to a set rule. As Figure 3 shown, the plurality of lens units 121 can form concentric circles arranged in a radially expanding manner in sequence. When the projection screen is applied to an ultra-short throw projection system, the center O of the lens units 121 in the shape of concentric circles is usually not located within the projection screen. When the projection device emits projection light from below the projection screen to the projection screen, the center O of each lens unit 121 is located below the side of the bottom of the projection screen and on the extension line of the symmetry axis I-I' of the projection screen. Along the direction from the bottom to the top of the projection screen, the radius of the lens unit 121 gradually increases, and the projection screen does not include a complete circular lens, but only includes a partial arc-shaped lens.

[0055] As Figure 2 shown, each lens unit 121 includes a lens surface x1 and a non-lens surface x2 that are connected to each other. Among them, the lens surface x1 is inclined with respect to the plane where the projection screen is located, and the inclination angle of the lens surface x1 is set according to the incident angle of the projection light, so as to reflect the projection light emitted by the projection device in the direction of the audience when it is incident on the reflection layer 13 on the surface of the lens surface x1. The non-lens surface x2 is used to connect the lens surface x1, and the non-lens surface x2 can be a plane or a curved surface.

[0056] Setting the Fresnel lens layer 12 in the projection screen is beneficial to reflecting the projection light forward of the projection screen, thereby improving the gain of the projection screen.

[0057] The reflection layer 13 covers at least the lens surfaces x1 of the lens units 121 of the Fresnel lens layer 12. Since the inclination angles of the lens surfaces x1 of the lens units 121 are all set to reflect the incident projection light in the direction of the audience, and the reflection layer 13 covers the lens surfaces x1 of the lens units 121 and has the same inclination angle as the lens surfaces x1, the incident projection light can be reflected in the direction of the audience according to the original design.

[0058] However, the projection screen can not only reflect the light from the projection device, but also reflect a part of the incident ambient light in the direction of the audience, resulting in the problem of reduced contrast of the projection image.

[0059] In view of this, the embodiments of the present invention provide a projection screen that can reduce the reflection of ambient light, thereby improving the contrast of the projection image.

[0060] As Figure 4As shown in the figure, the projection screen provided by the embodiment of the present utility model includes: a Fresnel lens layer 12, a reflection layer 13, a first light-transmitting medium layer 14, and a second light-transmitting medium layer 15. The Fresnel lens layer 12 includes a plurality of lens units 121. Each lens unit includes a lens surface x1 and a non-lens surface x2. The lens surface x1 is inclined with respect to the plane where the projection screen is located. The reflection layer 13 covers at least the lens surface x1 of each lens unit 121.

[0061] As Figure 4 shown in the figure, both the first light-transmitting medium layer 14 and the second light-transmitting medium layer 15 are located on the side of the Fresnel lens layer 12 facing the audience. Among them, the first light-transmitting medium layer 14 is closer to the Fresnel lens layer 12, and the second light-transmitting medium layer 15 is located on the side of the first light-transmitting medium layer 14 away from the Fresnel lens layer 12. The first light-transmitting medium layer 14 and the second light-transmitting medium layer 15 are in contact with each other. Among them, the refractive index of the second light-transmitting medium layer 15 is less than the refractive index of the first light-transmitting medium layer 14. Therefore, when light is incident on the interface between the first light-transmitting medium layer 14 and the second light-transmitting medium layer 15, refraction of light will occur at this interface.

[0062] Specifically, as Figures 5 - 7 shown in the figure, when light is incident from the first medium to the second medium, refraction of light will occur at the interface between the first medium and the second medium. The refractive index of the first medium is n1, the refractive index of the second medium is n2, and the normal line perpendicular to the interface is t. Then the angle between the incident light l1 and the normal line t is the incident angle θ1, and the angle between the refracted light l2 and the normal line t is the refraction angle θ2. When the law of refraction of light occurs, it satisfies the law of refraction:

[0063] n1sinθ1 = n2sinθ2.

[0064] As Figure 5 shown in the figure, when light is incident from an optically thinner medium to an optically denser medium, that is, the refractive index n1 of the first medium is less than the refractive index n2 of the second medium, the incident angle θ1 is greater than the refraction angle θ2, and the light will be deflected towards the direction close to the normal line t.

[0065] As Figure 6 shown in the figure, when light is incident from an optically denser medium to an optically thinner medium, that is, the refractive index n1 of the first medium is greater than the refractive index n2 of the second medium, the incident angle θ1 is less than the refraction angle θ2, and the light will be deflected away from the normal line t.

[0066] As Figure 7 shown in the figure, when light is incident from an optically denser medium to an optically thinner medium, that is, the refractive index n1 of the first medium is greater than the refractive index n2 of the second medium, and when the incident angle θ1 of the incident light l1 increases to a certain extent, the refraction angle θ2 of the refracted light l2 will increase to 90 degrees, that is, there is no refracted light in the second medium, and all the light is reflected. This situation is called total internal reflection of light.

[0067] Then according to Figure 7 the refraction of light, the critical angle θ of total internal reflection of light can be calculated as follows:

[0068] n1sinθ = n2sin90°;

[0069] θ = arcsin(n2 / n1);

[0070] When light is incident from an optically denser medium to an optically rarer medium, total internal reflection will occur when the incident angle is greater than or equal to the critical angle θ.

[0071] In the embodiment of the present invention, based on the above principle, the refractive index of the first light-transmitting medium layer 14 is set to be greater than that of the second medium layer 15. Then, whether it is projection light or ambient light, after being incident on the projection screen and reflected by the reflection layer 13, it will be incident from the first light-transmitting medium layer 14 to the second light-transmitting medium layer 15. As Figure 4 shown, in the embodiment of the present invention, the difference in the refractive indices of the first light-transmitting medium layer 14 and the second light-transmitting medium layer 15 satisfies that the projection light L incident on the projection screen is reflected by the reflection layer 13 and then incident on the first light-transmitting medium layer 14, and is transmitted through the first light-transmitting medium layer 14 and the second light-transmitting medium layer 15 and then exits; while the ambient light C incident on the projection screen is reflected by the reflection layer 13 and then incident on the first light-transmitting medium layer 14, and is totally reflected at the interface between the first light-transmitting medium layer 14 and the second light-transmitting medium layer 15, thereby reducing the exit of ambient light and improving the contrast of the projection light.

[0072] The projection screen provided by the embodiment of the present invention can be used in conjunction with an ultra-short-throw projection device. The projection device is usually located below the projection screen and emits projection light obliquely upward to the projection screen. The positions between the projection device and the projection screen are relatively fixed. Therefore, the incident angles of the projection light emitted by the projection device when incident on different positions of the projection screen are different. In practical applications, the incident angle of the projection light when incident on the projection screen is 60° - 85°.

[0073] The projection light L first enters the second light-transmitting medium layer 15. Since the refractive index of the second light-transmitting medium layer 15 is greater than that of air, the incident projection light will not undergo total internal reflection at the incident surface of the second light-transmitting medium layer. The projection light L will also undergo multiple refractions at the interfaces such as the first light-transmitting medium layer 14 and the Fresnel lens layer 12 and then enter the reflection layer 13. Since the inclination angle of the lens surface x1 of each lens unit 121 of the Fresnel lens layer 12 with respect to the plane where the projection screen is located is designed according to the incident direction of the projection light and finally reflects the incident light directly in front of the projection screen, usually the inclination angle of the lens surface x1 of each lens unit 121 is designed with the incident angle θ = 12° to 17° when the projection light enters the lens surface x1 of each lens unit 121. When the projection light L reflected by the reflection layer 13 enters the first light-transmitting medium layer 14 again, the incident angle is within the range of ±10°. This angle is relatively small and will not undergo total internal reflection at the interface between the first light-transmitting medium layer 14 and the second light-transmitting medium layer 15, so it exits directly in front of the projection screen and can be received by the audience.

[0074] The ambient light C is usually the light emitted by the lamps located on the ceiling. Therefore, the incident angle when it enters the projection screen is usually large and diverse. The ambient light will also undergo multiple refractions at the interfaces of different film layers during the process of entering the projection screen and then enter the reflection layer 13. However, the inclination angle of the reflection layer 13 is not designed according to the incident angle of the ambient light C. Therefore, the incident angle of the ambient light C reflected by the reflection layer 13 when it enters the first light-transmitting medium layer 14 is relatively large. Therefore, the reflection layer 13 totally reflects all the light that enters the interface between the first light-transmitting medium layer 14 and the second light-transmitting medium layer 15 among the reflected ambient light as long as the incident angle is greater than or equal to the critical angle, thus reducing the ambient light reflected by the projection screen.

[0075] The difference in refractive indices between the first light-transmitting medium layer 14 and the second light-transmitting medium layer 15 determines the critical angle when total internal reflection of light occurs. When the difference between the first light-transmitting medium layer 14 and the second light-transmitting medium layer 15 is larger, the critical angle is smaller, meaning more incident light may undergo total internal reflection; when the difference between the first light-transmitting medium layer 14 and the second light-transmitting medium layer 15 is smaller, the critical angle is larger, meaning fewer incident light may undergo total internal reflection. According to the application scenario of the ultra-short throw projection system, in order to make more ambient light be totally reflected and reduce the total internal reflection of the projection light, the difference in refractive indices between the first light-transmitting medium layer 14 and the second light-transmitting medium layer 15 can be greater than or equal to 0.2 and less than or equal to 0.8.

[0076] In some embodiments, the first light-transmitting medium layer 14 may be made of an organic resin material, and the first light-transmitting medium layer 14 may also be used to bond the film layers on both sides. For example, the first light-transmitting medium layer 14 may be made of a sticky material such as epoxy resin, acrylic resin, silicone resin, etc. Then, the refractive index of the first light-transmitting medium layer 14 may be about 1.49.

[0077] In some embodiments, the second light-transmitting medium layer 15 may be made of an inorganic material or an organic material. For example, the second light-transmitting medium layer 15 may be made of MgF2, CaF2, PTFE, hollow silicate, etc. Correspondingly, the refractive index of the second light-transmitting medium layer may be 1.28 to 1.40.

[0078] For example, when the refractive index of the first light-transmitting medium layer 14 is 1.49 and the refractive index of the second light-transmitting medium layer 15 is 1.28, the critical angle for total reflection at the interface between the first light-transmitting medium layer 14 and the second light-transmitting medium layer 15 is about 59°. Therefore, the ambient light C with a large outgoing angle that is reflected will be totally reflected, while the outgoing angle of the projection light after reflection is within the range of ±10°, so total reflection will not occur and it can be transmitted through the first light-transmitting medium layer 14 and the second light-transmitting medium layer 15.

[0079] In some embodiments, as Figure 8 shown, the first light-transmitting medium layer 14 may also be mixed with a light-absorbing material. The light-absorbing material has the property of absorbing incident light. In specific implementation, the light-absorbing material may be a dark substance such as carbon black or dye. The overall projection screen mixed with the light-absorbing material has a dark appearance, which can improve the black luminance of the projection screen. Mixing the light-absorbing material in the first light-transmitting medium layer 14 can play a role in absorbing ambient light, thereby improving the contrast of the projection image to a certain extent. And since the ambient light, after being reflected by the reflection layer 13 when incident on the projection screen, will undergo total reflection at the interface between the first light-transmitting medium layer 14 and the second light-transmitting medium layer 15, the ambient light will then enter the first light-transmitting medium layer 15 again and be absorbed to a certain extent by the light-absorbing material in the first light-transmitting medium layer 15. This increases the number of penetration times of the ambient light in the first light-transmitting medium layer 15 and improves the absorption rate of the ambient light.

[0080] In some embodiments, as Figure 8As shown, the surface of the second light-transmitting medium layer 15 on the side facing away from the first light-transmitting medium layer 14 is a rough surface. As described above, when the projection light entering the projection screen exits the projection screen after being reflected by the reflection layer 13, the angle is within the range of ±10°, and the viewing angle is small, resulting in a narrow viewing range of the projection image. By setting the outermost surface of the second light-transmitting medium layer 15 as a rough surface, the projection light can be diffused before exiting, thereby increasing the exit angle of the projection light and increasing the viewing angle of the projection screen. At the same time, making the surface of the projection screen have a certain diffusivity is also beneficial to suppressing the formation of laser speckles when the projection system uses a laser light source and optimizing the projection image.

[0081] In some embodiments, as Figure 9 and Figure 10 shown, the projection screen may further include a diffusion layer 11 located on the surface of the second light-transmitting medium layer 15 on the side facing away from the first light-transmitting medium layer 14. The diffusion layer 11 is a separately provided film layer and has the function of light diffusion, which can make the projection light exiting from the projection screen have a certain divergence angle and increase the viewing angle of the audience to view the projection image. In addition, the diffusion layer 11 is also beneficial to suppressing the generation of laser speckles and optimizing the projection image.

[0082] As Figure 9 shown, the diffusion layer 11 may be a diffusion material 112 located on the surface of the second light-transmitting medium layer 15. The diffusion material can usually be formed on the surface of the second light-transmitting medium layer 15 by processes such as sandblasting.

[0083] Alternatively, as Figure 10 shown, the diffusion layer 11 may include a first substrate 111 and a diffusion material 112 located on one surface of the first substrate 111; wherein, the diffusion material 112 is located on the surface of the first substrate 111 facing away from the second light-transmitting medium layer 15.

[0084] The diffusion material 112 can be, but is not limited to, silica particles, aluminum oxide particles, titanium oxide particles, cerium oxide particles, zirconium oxide particles, tantalum oxide particles, zinc oxide particles, magnesium fluoride particles, etc.

[0085] The first substrate 111 can be, but is not limited to, materials such as PET, PEN, PC, PMMA, TAC, COP, TPU, PVC, PI, PA, PE, PP, etc.

[0086] In some embodiments, as Figure 11As shown, the diffusion layer 11 may only include the first substrate 111, which has a light diffusion property by doping diffusion particles in the first substrate 111. Alternatively, the surface of the first substrate 111 on the side facing away from the second light-transmitting medium layer 15 is an uneven surface. The uneven surface may be formed by sandblasting or alkali treatment of the surface of the first substrate 111, which is not limited herein. The first substrate 111 can play a certain role in light diffusion and atomization, thereby expanding the viewing angle, resisting ceiling reflection, etc.

[0087] In some embodiments, as Figure 11 shown, the Fresnel lens layer may include: a second substrate 122 and a plurality of lens units 121 located on one surface of the second substrate 122.

[0088] The second substrate 122 may be made of, but not limited to, materials such as PET, PEN, PC, PMMA, TAC, COP, TPU, PVC, PI, PA, PE, PP, etc. Each lens unit 121 may be formed by coating an ultraviolet curable resin on a mold having a Fresnel structure and imprinting and UV-curing the ultraviolet curable resin with the second substrate 122.

[0089] In some embodiments, as Figure 12 shown, the Fresnel lens layer 12 is an integral structure. One surface of the Fresnel lens layer 12 is the lens unit 121, and the other surface is a plane. The integral structure of the Fresnel lens layer 12 can save the process of combining the substrate and the lens unit, and can simplify the manufacturing process.

[0090] As Figure 12 shown, each lens unit 121 of the Fresnel lens layer is located on the side facing away from the first light-transmitting medium layer 14, and the reflective layer 13 is located on the surface of each lens unit 121. The incident projection light needs to pass through the Fresnel lens layer 12 and enter the reflective layer 13. The surface of the reflective layer 13 in contact with the lens unit is a reflective surface. Therefore, there are no special requirements for the production of the reflective layer 13, and the reflective layer 13 can be formed by processes such as coating aluminum paste or coating on the lens unit 121.

[0091] In some embodiments, as Figure 13 shown, each lens unit 121 of the Fresnel lens layer is located on the side facing the first light-transmitting medium layer 14. Each lens unit 121 is buried in the first light-transmitting medium layer 14. The first light-transmitting medium layer 14 can play a role in protecting the Fresnel structure and the reflective layer. Since the Fresnel lens layer 12 is located on the side farthest from the audience and no light enters the Fresnel lens layer 12, the requirements for the light transmittance and damage specifications of the Fresnel lens layer 12 are reduced. There is no need to use expensive optical materials to make the Fresnel lens layer 12, and relatively inexpensive industrial materials can be used for production, thereby reducing production costs.

[0092] To further improve the contrast of the projected image, the reflective layer 13 may also have the property of wavelength-selective reflection, and its reflectivity to the projection light emitted by the projection device is greater than that to the light of other wavelengths. The reflective layer 13 can selectively enhance the reflection of the projection light emitted by the projection device by using the principle of resonance enhancement of the light of a set wavelength, while the light of other wavelengths is absorbed, so that a black appearance is 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.

[0093] As Figure 14 shown, at this time, the reflective layer may include: a semi-transparent layer 131, a reflective layer 132, and a light-transmitting medium layer 133. The semi-transparent layer 131, the light-transmitting medium layer 133, and the reflective layer 132 are sequentially formed on the lens surfaces of the lens units of the Fresnel lens layer. A resonance structure is formed by the semi-transparent layer 131, the light-transmitting medium layer 133, and the reflective layer 132.

[0094] Among them, the semi-transparent layer 131 has the property of semi-transmission and semi-reflection. It should be noted that the semi-transmission and semi-reflection property mentioned in the embodiments of the present invention does not mean that the light transmittance and reflectivity are both 50% for the light, but to indicate that the semi-transparent layer 131 can achieve the property of partially transmitting and partially reflecting the light, and its transmittance and reflectivity can be adjusted according to actual requirements. The specific transmittance and reflectivity of the semi-transparent layer 131 are not limited herein. The semi-transparent layer 131 can allow the projection light to enter the resonance structure when the projection light is incident on the projection screen, and the projection light can also be emitted from the semi-transparent layer 131 after oscillating and enhancing in the resonance structure. In specific implementation, the semi-transparent layer 131 can be formed by at least one metal such as Al, Nb, Ag, and Ti or a laminated structure formed by two or more metals.

[0095] 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, a material with reflective properties and no light-transmitting properties can be used for production. In specific implementation, the reflective layer 132 can be made of materials such as Al, aluminum alloy, Ag, or silver alloy, and the thickness of the reflective layer 132 is greater than the thickness of the semi-transparent layer 131.

[0096] The thickness of the light-transmitting medium layer 133 determines the cavity length of the resonance structure. Therefore, the product of the refractive index and the thickness of the light-transmitting medium layer 133 determines the wavelength of the light that can be reflected. Then, when designing the resonance structure, a dielectric material whose product of the refractive index and the thickness satisfies the resonance condition for the projection light emitted by the projection device needs to be selected. In specific implementation, the light-transmitting medium layer 133 can be made of materials such as metal oxides, nitrides, or transparent resins.

[0097] The semi-transmissive layer 131, the light-transmissive medium layer 133, and the reflective layer 132 can all be fabricated using sputtering or evaporation processes. When the above resonance structure is adopted, a dielectric material with an appropriate refractive index is selected as the light-transmissive medium layer 133, and the light-transmissive medium layer 133 is set to an appropriate thickness, which can enhance the reflection of the projection light.

[0098] In the embodiment of the present utility model, the projection light source can adopt a three-color laser light source device. The three-color laser light source device can emit red laser light, green laser light, and blue laser light. Then, by adjusting the material refractive index and thickness of the light-transmissive medium layer, the resonance structure can enhance the reflection of red laser light, green laser light, and blue laser light simultaneously, and at the same time attenuate the reflection of light in other wavelength bands, thereby improving the contrast of the projection image.

[0099] Based on the same inventive concept, the embodiment of the present utility model further provides a projection system, as Figure 1 shown. The projection system includes: a projection device 2 and a projection screen 1 located on the light-emitting side of the projection device 2.

[0100] As Figure 15 shown, the projection device includes: a light source device 21, an illumination optical path 22, a display element 23, and a lens 24. Among them, the illumination optical path 22 is located on the light-emitting side of the light source device 21, the display element 23 is located on the light-emitting side of the illumination optical path 22, and the lens 24 is located on the light-emitting side of the display element 23.

[0101] The light source device 21 can adopt a laser light source device. The laser light source device can adopt a single-color laser or a laser that can emit multiple colors of laser light or multiple lasers that emit different colors of laser light. When the laser light source device adopts a single-color laser, the laser display device also needs to be provided with a color wheel for color conversion. The single-color laser and the color wheel can be used to achieve the purpose of emitting different primary color lights in sequence. When the laser light source device adopts a laser that can emit multiple colors of laser light, it is necessary to control the laser light source to emit different colors of laser light as primary color lights in sequence.

[0102] In the embodiment of the present utility model, the light source device can adopt a three-color laser light source device. The three-color laser light source device can be a laser that emits three primary color laser lights, such as an MCL laser, etc.; or it can include a red laser, a green laser, and a blue laser that respectively emit three primary color laser lights. Adopting a three-color laser light source device is beneficial to improving the color gamut of the projection image, has better color expressiveness, and can accurately reproduce the input image.

[0103] The illumination light path 22 is located on the light-emitting side of the light source device 21. The illumination light path 22 collimates the light emitted by the light source device 21 and allows the light emitted by the light source device 21 to be incident on the display element 23 at a suitable angle. The illumination light path 22 may include multiple lenses or lens groups, which are not limited here.

[0104] Display element 23 is used to modulate incident light. In a specific implementation, display element 23 can employ a digital micromirror device (DMD). After passing through illumination optical path 22, the light beam conforms to the illumination size and incident angle required by the DMD. The DMD surface includes numerous tiny mirrors, each of which can be individually driven to deflect. By controlling the DMD's deflection angle, the brightness of the light incident on lens 24 is controlled.

[0105] The lens 24 is used to form an image of the light emitted from the display element 23 . After the light is formed by the lens 24 , the image is projected.

[0106] In the embodiment of the present invention, the projection device 2 can be an ultra-short-throw projection device, that is, the lens 24 in the projection device is an ultra-short-throw 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, thereby shortening the projection distance and achieving large-scale image display.

[0107] Projection screen 1 is located on the light-emitting side of the lens in the projection device. Projection screen 1 includes a Fresnel lens layer, a reflective layer located on the surface of each lens unit of the Fresnel lens layer, and a first light-transmitting medium layer and a second light-transmitting medium layer located on the side of the Fresnel lens layer facing away from the reflective layer. The refractive index of the first light-transmitting medium layer is greater than the refractive index of the second light-transmitting medium layer, and the difference in refractive index between the first light-transmitting medium layer and the second light-transmitting medium layer satisfies the following conditions: projection light incident on the projection screen is reflected by the reflective layer, then incident on the first light-transmitting medium layer, and then transmitted by the first light-transmitting medium layer and the second light-transmitting medium layer before exiting; while ambient light incident on the projection screen is reflected by the reflective layer, then incident on the first light-transmitting medium layer, and is totally reflected at the interface between the first light-transmitting medium layer and the second light-transmitting medium layer. This reduces the emission of ambient light, thereby improving the contrast of the projection light.

[0108] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional 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 that fall within the scope of the present invention.

[0109] Obviously, those skilled in the art can make various modifications and variations to the present utility model without departing from the spirit and scope of the present utility model. Thus, if these modifications and variations of the present utility model fall within the scope of the claims of the present utility model and its equivalent technologies, the present utility model also intends to include these modifications and variations therein.

Claims

1. A projection screen, characterized in that include: Fresnel lens layer; the Fresnel lens layer includes a plurality of lens units, each lens unit includes a lens surface and a non-lens surface; the lens surface is tilted relative to the plane where the projection screen is located; a reflective layer, covering at least the lens surface of each lens unit; A first light-transmitting medium layer is located on the side of the Fresnel lens layer facing the audience; and a second light-transmitting medium layer, located on a side of the first light-transmitting medium layer away from the Fresnel lens layer; The refractive index of the second light-transmitting medium layer is smaller than the refractive index of the first light-transmitting medium layer, and the difference in refractive index between the first light-transmitting medium layer and the second light-transmitting medium layer satisfies the following conditions: projection light incident on the projection screen is reflected by the reflective layer and then incident on the first light-transmitting medium layer, and is transmitted by the first light-transmitting medium layer and the second light-transmitting medium layer before being emitted; The ambient light incident on the projection screen is reflected by the reflective layer and then incident on the first light-transmitting medium layer, and is totally reflected at the interface between the first light-transmitting medium layer and the second light-transmitting medium layer.

2. The projection screen according to claim 1, wherein, The first light-transmitting medium layer is mixed with light-absorbing material.

3. The projection screen according to claim 1 or 2, characterized in that, A difference between a refractive index of the first light-transmitting medium layer and a refractive index of the second light-transmitting medium layer is greater than or equal to 0.2 and less than or equal to 0.

8.

4. The projection screen according to claim 3, characterized in that, The refractive index of the second light-transmitting medium layer is 1.28-1.

40.

5. The projection screen according to claim 1 or 2, characterized in that, A surface of the second light-transmitting medium layer facing away from the first light-transmitting medium layer is a rough surface.

6. The projection screen according to claim 1 or 2, characterized in that, The projection screen also includes: The diffusion layer is located on a surface of the second light-transmitting medium layer that is away from the first light-transmitting medium layer.

7. The projection screen according to claim 6, wherein, The diffusion layer is a diffusion material located on the surface of the second light-transmitting medium layer; Alternatively, the diffusion layer includes a first substrate and a diffusion material located on one surface of the first substrate.

8. The projection screen according to claim 1 or 2, characterized in that, The Fresnel lens layer includes: a second substrate and a plurality of lens units located on a surface of one side of the second substrate; or the Fresnel lens layer is an integral structure, one surface of the Fresnel lens layer is a plane, and a surface opposite to the plane includes a plurality of lens units; Each of the lens units is located on a side away from the first light-transmitting medium layer; or each of the lens units is located on a side facing the first light-transmitting medium layer.

9. The projection screen according to claim 1 or 2, characterized in that, The reflectivity of the reflective layer to the projection light emitted by the projection device is greater than the reflectivity to light of other wavelengths.

10. A projection system, characterized in that, include: A projection device, for emitting projection light; and a projection screen, located on the light-emitting side of the projection device, wherein the projection screen is the projection screen according to any one of claims 1 to 9; Wherein, the projection device is an ultra-short-throw laser projection device; the projection device includes: A three-color laser light source device for emitting three-primary-color lasers; A display element is located on the light-emitting side of the three-color laser light source device and is used to modulate the laser light emitted by the three-color laser light source device to form a display image; and The lens is located on the light-emitting side of the display element and projects the light emitted by the display element into an image.

Images