Projection film and preparation method thereof, and projection display assembly

Abstract

The present application discloses a projection film, a preparation method thereof, and a projection display assembly. The projection film includes: a substrate; a microlens layer formed on the surface of the substrate; a reflective layer covering the side of the microlens layer facing away from the substrate; wherein the transmittance of the reflective layer is greater than zero; and a transparent layer covering the side of the reflective layer facing away from the microlens layer; wherein the relative relationship between the refractive index of the transparent layer and the refractive index of the microlens layer satisfies a preset condition so that the propagation direction of the transmitted light beam passing through the reflective layer in the transparent layer and the microlens layer is the same. The projection display assembly includes a projection display panel and a projection film. The present application transmits external light from an external scene while reflecting the projection light emitted by the image generation unit, so that the user can not only see the projected image on the projection film, but also see the external scene through the projection film, thereby realizing the combination of the projected image and the external scene and improving the user experience.

Description

Technical Field

[0001] The present application relates to the technical field of vehicle accessories, and in particular to a projection film and a preparation method thereof, and a projection display assembly. Background Art

[0002] To achieve high-gain projection images, diffusers and projectors are used in many applications, such as in-vehicle side and rear window displays, where human-machine interaction often requires them. However, diffusers in related technologies are only reflective, not transmissive. Consequently, users only see the projected image through the diffuser, unable to see the external scene through the diffuser. This prevents the user from integrating the projected image with the external scene, compromising the user experience.

[0003] Application Contents

[0004] The embodiments of the present application provide a projection film, a preparation method thereof, and a projection display assembly, which can reflect projection light while transmitting external light from an external scene, thereby combining the projected image with the external scene and improving the user experience.

[0005] According to an embodiment of the first aspect of the present application, a projection film includes: a substrate; a microlens layer formed on a surface of the substrate; a reflective layer covering a side of the microlens layer facing away from the substrate; wherein the transmittance of the reflective layer is greater than zero; and a transparent layer covering a side of the reflective layer facing away from the microlens layer; wherein the relative relationship between the refractive index of the transparent layer and the refractive index of the microlens layer satisfies a preset condition such that a transmitted light beam passing through the reflective layer propagates in the same direction in the transparent layer and the microlens layer.

[0006] According to an embodiment of the present application, the preset condition is that an absolute value of a difference between a refractive index of the transparent layer and a refractive index of the microlens layer is not greater than a predetermined threshold.

[0007] According to one embodiment of the present application, the predetermined threshold is 0.15.

[0008] According to one embodiment of the present application, the reflective layer includes a dielectric film coated on the microlens layer, and the difference between the refractive index of the dielectric film and the refractive index of the microlens layer is not less than 0.4.

[0009] According to one embodiment of the present application, the reflective layer includes a metal film coated on the microlens layer.

[0010] According to one embodiment of the present application, the reflectivity of the reflective layer is 10% to 20%.

[0011] According to one embodiment of the present application, the microlens layer includes a plurality of first microlenses, and the curved surfaces of the first microlenses are asymmetric about the central axis of the first microlenses in a line perpendicular to the substrate.

[0012] According to one embodiment of the present application, the curved surface of the first microlens is an aspherical surface.

[0013] According to one embodiment of the present application, a side of the transparent layer facing away from the reflective layer is a plane parallel to the plate surface of the substrate.

[0014] According to one embodiment of the present application, a plurality of micro-protrusions are formed on a side of the transparent layer facing away from the reflective layer, and a width of the micro-protrusions is no greater than 400 nm.

[0015] According to an embodiment of the present application, a plurality of second micro lenses are uniformly distributed on a side of the transparent layer facing away from the reflective layer, and a curvature radius of the second micro lenses is not less than 2 mm.

[0016] According to one embodiment of the present application, the microlens layer includes a plurality of first microlenses, which are distributed in an array; and / or a plurality of second microlenses are distributed in an array.

[0017] According to a second embodiment of the present application, a projection display assembly includes: a projection display panel; and any one of the projection films in the first embodiment, wherein a substrate of the projection film is attached to the projection display panel.

[0018] According to an embodiment of the third aspect of the present application, a method for preparing a projection film includes the following steps: providing a plurality of first microlenses on a surface of a substrate to form a microlens layer; coating a reflective material on a side of the microlens layer facing away from the substrate to form a reflective layer; wherein the transmittance of the reflective layer is greater than zero; and coating a transparent material on a side of the reflective layer facing away from the microlens layer to form a transparent layer; wherein the relative relationship between the refractive index of the transparent layer and the refractive index of the microlens layer satisfies a preset condition so that a transmitted light beam passing through the reflective layer propagates in the same direction in the transparent layer and the microlens layer.

[0019] The projection film, preparation method thereof, and projection display assembly provided in the embodiments of the present application adopt a reflective layer with a transmittance greater than zero, and respectively cover the two sides of the reflective layer with a microlens layer and a transparent layer whose relative refractive index relationship meets preset conditions. It is possible to transmit external light from the external scene while reflecting the projection light emitted by the image generation unit. Therefore, the user can not only see the projected image on the projection film, but also see the external scene through the projection film, thereby realizing the combination of the projected image and the external scene, and improving the user experience.

[0020] It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the present application, nor is it intended to limit the scope of the present application. Other features of the present application will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Other features, objects, and advantages of the present application will become more apparent by reading the detailed description of the non-limiting embodiments made with reference to the following drawings. The drawings are provided for a better understanding of the present invention and do not constitute a limitation of the present application. In the drawings:

[0022] Figure 1 is one of the longitudinal cross-sectional schematic diagrams of the projection film according to the present application;

[0023] Figure 2 is a partial longitudinal cross-sectional schematic diagram of the projection film according to the present application;

[0024] Figure 3 is a schematic diagram of the positional relationship between the projection film and the projector according to the present application;

[0025] Figure 4 is a schematic diagram of the working principle of the projection film according to the present application;

[0026] Figure 5 This is a second longitudinal cross-sectional schematic diagram of the projection film according to the present application;

[0027] Figure 6 3 is a longitudinal cross-sectional schematic diagram of the projection film according to the present application;

[0028] Figure 7 This is a light field diagram in the reflection direction when performing a projection simulation experiment using the projection film of the present application;

[0029] Figure 8 This is a light field diagram in the transmission direction when performing a projection simulation experiment using the projection film of the present application;

[0030] Figure 9 4 is a flow chart of a method for preparing a projection film according to the present application.

[0031] Reference numerals:

[0032] 100, projection film; 110, substrate; 120, microlens layer; 121, first microlens;

[0033] 130, reflecting layer; 131, rising curve segment; 132, descending curve segment;

[0034] 140. Transparent layer; 141. Micro-protrusion; 142. Second micro-lens; 200. Projector. DETAILED DESCRIPTION

[0035] In the description of the embodiments of the present application, it should be noted that the terms "longitudinal", "transverse", "upper", "lower", "top", "bottom", "inner", "outer", etc., indicating the orientation or state relationship, are based on the orientation or state relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, they should not be understood as limiting the embodiments of the present application. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and should not be understood as indicating or implying relative importance.

[0036] In the description of the embodiments of this application, it should be noted that, unless otherwise specified or limited, the terms "connected" and "connection" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium. Those skilled in the art will understand the specific meanings of the above terms in the embodiments of this application based on the specific circumstances.

[0037] In the embodiments of the present application, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Furthermore, a first feature being "above," "above," and "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0038] The following description of exemplary embodiments of the present application is made in conjunction with the accompanying drawings, including various details of the embodiments of the present application to facilitate understanding. These details should be considered as merely exemplary. Therefore, those skilled in the art will recognize that various changes and modifications may be made to the embodiments described herein without departing from the scope and spirit of the present application. Similarly, for the sake of clarity and conciseness, descriptions of well-known functions and structures are omitted in the following description.

[0039] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0040] like Figure 1As shown, the embodiment of the present application provides a projection film 100, which includes a substrate 110, a microlens layer 120, a reflective layer 130 and a transparent layer 140. The microlens layer 120 is formed on the plate surface of the substrate 110, the reflective layer 130 covers the side of the microlens layer 120 facing away from the substrate 110, and the transparent layer 140 covers the side of the reflective layer 130 facing away from the microlens layer 120. In other words, Figure 1 The illustrated orientation is used as a reference. The transparent layer 140, reflective layer 130, microlens layer 120, and substrate 110 are sequentially arranged from top to bottom. The reflective layer 130 has a transmittance greater than zero, and the refractive index of the transparent layer 140 and the refractive index of the microlens layer 120 satisfy a predetermined condition, ensuring that a light beam passing through the reflective layer 130 propagates in the same direction in the transparent layer 140 and the microlens layer 120.

[0041] Taking the projection film 100 as an example, the substrate 110 of the projection film 100 is attached to the glass panel of the vehicle window, and the image generation unit (PGU), such as the projector 200, is installed on the side of the transparent layer 140 facing away from the reflective layer 130. The working principle of the projection film 100 in the embodiment of the present application is described below:

[0042] like Figure 3 and Figure 4 As shown, because projector 200 is mounted on the side of transparent layer 140 facing away from reflective layer 130, incident light from projector 200 directly passes through transparent layer 140 and strikes reflective layer 130. The transmittance of reflective layer 130 is greater than zero. This means that a portion of the incident light striking reflective layer 130 is reflected back to form a projected image, while another portion passes through reflective layer 130 and enters microlens layer 120. Because the refractive index of transparent layer 140 and the refractive index of microlens layer 120 meet predetermined conditions, the light that passes through reflective layer 130 is emitted from substrate 110 in the direction of the incident light. Due to the reversibility of the optical path, external light striking substrate 110 maintains the same optical path direction and sequentially passes through microlens layer 120, reflective layer 130, and transparent layer 140. As a result, users can simultaneously view the projected image reflected by reflective layer 130 on projection film 100 while also viewing the external scene through projection film 100.

[0043] As can be seen from the above, the embodiment of the present application adopts a reflective layer 130 with a transmittance greater than zero, and covers the microlens layer 120 and the transparent layer 140 on both sides of the reflective layer 130, whose relative relationship of refractive indices meets the preset conditions. It can reflect the projection light emitted by the image generation unit while transmitting the external light from the external scene. Therefore, the user can not only see the projected image on the projection film 100, but also see the external scene through the projection film 100, thereby realizing the combination of the projected image and the external scene, and improving the user experience.

[0044] To ensure that the transmitted light beam passing through the reflective layer 130 propagates in the same direction in the transparent layer 140 and the microlens layer 120, the aforementioned preset condition may be that the absolute value of the difference between the refractive indices of the transparent layer 140 and the microlens layer 120 is no greater than a predetermined threshold. For example, the predetermined threshold is 0.15, and the difference between the refractive indices of the transparent layer 140 and the microlens layer 120 is within ±0.15. Alternatively, the preset condition may be that the ratio of the refractive indices of the transparent layer 140 to the microlens layer 120 is within a predetermined range, or that the refractive indices of the transparent layer 140 and the microlens layer 120 satisfy a certain functional relationship.

[0045] In some embodiments, the reflectivity of the reflective layer 130 is 10% to 20%, that is, the transmittance of the reflective layer 130 is 80% to 90%. The reflective layer 130 may include, but is not limited to, a metal film coated on the microlens layer 120, or a dielectric film applied to the microlens layer 120. When the reflective layer 130 includes a dielectric film, the difference between the refractive index of the dielectric film and the refractive index of the microlens layer 120 is not less than 0.4, that is, the refractive index of the dielectric film minus the refractive index of the microlens layer 120 ≥ 0.4, to improve the reflectivity.

[0046] The material of the metal film may be, but is not limited to, Ag, Ni, or Cr. The material of the dielectric film may be, but is not limited to, titanium nitride, aluminum oxide, zinc sulfide, zinc selenide, titanium monoxide, titanium dioxide, titanium dioxide, or titanium pentoxide.

[0047] In order to ensure that the incident light emitted by the projector 200 is reflected in all directions by the reflective layer 130 and to achieve uniform diffusion of the reflected light, the surface of the reflective layer 130 is non-planar. Since the reflective layer 130 covers the surface of the microlens layer 120, the shape of the microlens layer 120 directly determines the shape of the surface of the reflective layer 130. Specifically, Figure 1 and Figure 2 As shown, the microlens layer 120 includes a plurality of first microlenses 121. The curved surface of the first microlens 121 is asymmetric about the central axis of the first microlens 121 in a direction perpendicular to the substrate 110. Figure 2As shown, the curved surface of the first microlens 121 includes a rising curve segment 131 and a descending curve segment 132 connected to the rising curve segment 131 in a direction perpendicular to the substrate 110. The rising curve segment 131 and the descending curve segment 132 have different inclination angles relative to the surface of the substrate 110. The inclination angles of the rising curve segment 131 and the descending curve segment 132 can be determined based on the incident angle of the incident light and the material of the reflective layer 130. Furthermore, the curved surface of the first microlens 121 is aspherical, and the surface equation of the curved surface of the first microlens 121 is:

[0048]

[0049] In the reference plane parallel to the plate surface of the substrate 110, the central axis of the first microlens 121 is taken as the origin, z represents the height of any point on the surface of the first microlens 121 from the reference plane, and r x Represents the distance between any point and the central axis along the direction of the first axis, r y Indicates the distance between any point and the central axis along the direction of the second axis, C x represents the curvature of the surface of the first microlens 121 along the first axis, C y K represents the curvature of the surface of the first microlens 121 along the second axis direction, x K represents the conic coefficient of the surface of the first microlens 121 along the first axis direction, y represents the conic coefficient of the surface of the first microlens 121 along the second axis direction.

[0050] In some embodiments, the plurality of first microlenses 121 may be distributed in an array on the surface of the substrate 110. To fully utilize the surface of the substrate 110 and increase the number of first microlenses 121, the distribution shape of all first microlenses 121 is the same as the surface shape of the substrate 110. For example, when the surface shape of the substrate 110 is rectangular, all first microlenses 121 may be distributed in a rectangular array. When the surface shape of the substrate 110 is circular, all first microlenses 121 may be distributed in a circular array.

[0051] In addition, according to the process requirements, the side of the transparent layer 140 facing away from the reflective layer 130 can be either flat or uneven, for example:

[0052] like Figure 1 As shown, in some embodiments, in order to improve the clarity of the transparent layer 140, the side of the transparent layer 140 facing away from the reflective layer 130 is a plane parallel to the plate surface of the substrate 110. The projection film 100 in this embodiment is used to conduct a projection simulation experiment 1. Figure 3As shown, the projector 200 is mounted on the side of the transparent layer 140 facing away from the reflective layer 130, and the incident angle of the light emitted by the projector 200 on the transparent layer 140 is 10°. The transparent layer 140 is made of a glue layer with a refractive index of 1.52, and the side of the transparent layer 140 facing away from the reflective layer 130, i.e., the surface of the transparent layer 140 facing the projector 200, is a flat surface.

[0053] like Figure 5 As shown, in some embodiments, in order to improve the transmittance of the transparent layer 140, a plurality of micro-protrusions 141 are formed on the side of the transparent layer 140 facing away from the reflective layer 130. The width of the micro-protrusions 141 is not greater than 400 nm. The micro-protrusions 141 can be, but are not limited to, prisms, pyramids, or cones. The following uses the micro-protrusions 141 as an example to conduct a second projection simulation experiment on the projection film 100 of this embodiment. Figure 3 As shown, the projector 200 is mounted on the side of the transparent layer 140 facing away from the reflective layer 130, and the incident angle of the light emitted by the projector 200 on the transparent layer 140 is 10°. The transparent layer 140 is made of a glue layer with a refractive index of 1.52. The side of the transparent layer 140 facing away from the reflective layer 130, i.e., the surface of the transparent layer 140 facing the projector 200, is uniformly distributed with a plurality of pyramid-shaped micro-protrusions 141 in a rectangular array. The width of the micro-protrusions 141, i.e., the dimension of the micro-protrusions 141 in a direction parallel to the width of the substrate 110, is 320 nm, and the height of the micro-protrusions 141, i.e., the dimension of the micro-protrusions 141 in a direction perpendicular to the surface of the substrate 110, is 600 nm.

[0054] like Figure 6 As shown, in some embodiments, in order to improve the transmittance of the transparent layer 140, a plurality of second micro lenses 142 are uniformly distributed on the side of the transparent layer 140 facing away from the reflective layer 130, and the curvature radius of the second micro lenses 142 is not less than 2 mm. The projection film 100 in this embodiment is subjected to a third projection simulation experiment. Figure 3 As shown, the projector 200 is mounted on the side of the transparent layer 140 facing away from the reflective layer 130, and the incident angle of the light emitted by the projector 200 on the transparent layer 140 is 10°. The transparent layer 140 is made of a glue layer with a refractive index of 1.52. A plurality of second microlenses 142 are uniformly distributed in a rectangular array on the side of the transparent layer 140 facing away from the reflective layer 130, i.e., the surface of the transparent layer 140 facing the projector 200. The width of the second microlenses 142, i.e., the dimension of the second microlenses 142 in a direction parallel to the width of the substrate 110, is 200 nm, and the radius of curvature of the second microlenses 142 is 2 mm.

[0055] In the above-mentioned projection simulation experiments 1 to 3, the reflective layer 130 of the projection film 100 was an aluminum oxide dielectric film with a thickness of 67 nm and a transmittance of 90%, i.e., a transmittance ratio of 9:1; the substrate 110 was a glue layer, and the microlens layer 120 was a microlens layer with a refractive index of 1.52. All first microlenses 121 of the microlens layer 120 were distributed in a rectangular array on the surface of the substrate 110. The length and width of the projection of the first microlenses 121 on the substrate 110 were both 30 μm. The curved surface of the first microlenses 121 satisfied the surface equation described above, and the surface inclination angle was 4°, i.e., the inclination angle of the rising curve segment 131 and the descending curve segment 132 of the first microlens 121 relative to the substrate 110 differed by 4°. The conic coefficient K of the curved surface of the first microlens 121 along the x-axis is: x and the conic coefficient K of the curved surface of the first microlens 121 along the y-axis direction y are both -0.75, and the curvature C of the curved surface of the first microlens 121 along the x-axis direction x and the curvature C of the curved surface of the first microlens 121 along the y-axis direction y The xy plane is parallel to the surface of the substrate 110 .

[0056] like Figure 7 As shown in FIG. 1 , the results of the projection simulation experiments 1 to 3 are that the diffusion range of the reflected light reflected by the reflective layer 130 is 47°*47°, and as shown in FIG. Figure 8 As shown in the results of projection simulation experiments 1 to 3, the diffusion range of the transmitted light transmitted through the reflective layer 130 is zero, that is, the projection of the transmitted light passing through the projection film 100 on the plane parallel to the substrate 110 is a light point. It should be noted that after changing the transmittance of the reflective layer 130, Figure 7 and Figure 8 Only the brightness changes, and the transmittance of the reflective layer 130 may be, but is not limited to, 9:1, 8:2, or 6:4.

[0057] Furthermore, to fully utilize the surface of the transparent layer 140 and increase the number of second microlenses 142, the distribution shape of all second microlenses 142 is the same as the projection shape of the transparent layer 140 on the substrate 110. For example, when the projection shape of the transparent layer 140 on the substrate 110 is rectangular, all second microlenses 142 may be distributed in a rectangular array. When the projection shape of the transparent layer 140 on the substrate 110 is circular, all second microlenses 142 may be distributed in a circular array. Furthermore, the transparent layer 140 and the substrate 110 may be, but are not limited to, a glue layer, a glass plate, or a transparent plastic plate.

[0058] In addition, an embodiment of the present application further provides a projection display assembly, comprising a projection display panel and the projection film 100. The substrate 110 of the projection film 100 is attached to the projection display panel. The projection display panel in this embodiment can be a windshield, rear window, or side window.

[0059] The projection display assembly in the present application adopts the above-mentioned projection film 100, which can transmit external light from the external scene while reflecting the projection light emitted by the image generation unit. Therefore, the user can not only see the projected image on the projection display assembly, but also see the external scene through the projection display assembly, thereby realizing the combination of the projected image and the external scene and improving the user experience.

[0060] like Figure 9 As shown, the embodiment of the present application further provides a method for preparing a projection film 100, the method comprising the following steps:

[0061] S1. Arrange a plurality of first micro lenses 121 on a surface of a substrate 110 to form a micro lens layer 120. The substrate 110 may be, but is not limited to, a glue layer, a glass plate, or a transparent plastic plate.

[0062] S2. Covering the side of the microlens layer 120 facing away from the substrate 110 with a reflective material to form a reflective layer 130 ; wherein the transmittance of the reflective layer 130 is greater than zero.

[0063] S3. A transparent material is applied to the side of the reflective layer 130 facing away from the microlens layer 120 to form a transparent layer 140. The relative relationship between the refractive index of the transparent layer 140 and the refractive index of the microlens layer 120 satisfies a preset condition so that the transmitted light beam passing through the reflective layer 130 propagates in the same direction in the transparent layer 140 and the microlens layer 120.

[0064] In step S1, all first microlenses 121 can be arranged on the surface of the substrate 110 according to the regularity of array distribution. In addition, in order to achieve uniform diffusion of reflected light, the first microlenses 121 can be microlenses with aspherical curved surfaces and asymmetric curves perpendicular to the substrate 110 about the central axis of the first microlenses 121.

[0065] In step S2, the reflective material can be, but is not limited to, a metal material or a dielectric material, as long as the transmittance of the reflective layer 130 is greater than zero, achieving both transmission and reflection. When the reflective material is a metal material such as Ag, Ni, or Cr, the reflective material can be attached to the surface of the microlens layer 120 by plating to form a translucent metal film. When the reflective material is a dielectric material such as titanium nitride, aluminum oxide, or titanium dioxide, the reflective material can be attached to the surface of the microlens layer 120 by painting to form a dielectric film. In addition, to achieve uniform diffusion of reflected light and ensure that the incident light emitted by the projector 200 is reflected in all directions by the reflective layer 130, when the reflective layer 130 includes a dielectric film, the difference between the refractive index of the dielectric film and the refractive index of the microlens layer 120 is no less than 0.4.

[0066] In step S3, the transparent material may be, but is not limited to, glass, glue, or transparent plastic. When the transparent material is glue, the glue can be applied to the surface of the reflective layer 130 by scraping, and a glue layer can be formed after the glue solidifies. Furthermore, the preset condition in step S3 may be that the absolute value of the difference between the refractive index of the transparent layer 140 and the refractive index of the microlens layer 120 is no greater than a predetermined threshold. For example, the predetermined threshold is 0.15, and the difference between the refractive index of the transparent layer 140 and the refractive index of the microlens layer 120 is within ±0.15. Alternatively, the preset condition may be that the ratio of the refractive index of the transparent layer 140 to the refractive index of the microlens layer 120 is within a predetermined range, or that the refractive index of the transparent layer 140 and the refractive index of the microlens layer 120 satisfy a certain functional relationship.

[0067] It should be noted that, depending on process requirements, step S4 may be performed after step S3. S4: A plurality of micro-protrusions 141 having a width no greater than 400 nm are provided on the side of the transparent layer 140 facing away from the reflective layer 130. The micro-protrusions 141 may be arranged on the surface of the transparent layer 140 in an array distribution pattern. The micro-protrusions 141 may be, but are not limited to, prisms, pyramids, or cones.

[0068] The method for preparing the projection film 100 further includes step S5, which can replace step S4. That is, in some embodiments, step S5 is performed after completing step S3. S5: A plurality of second microlenses 142 having a radius of curvature of no less than 2 mm are disposed on the side of the transparent layer 140 facing away from the reflective layer 130. In step S5, all second microlenses 142 can be arranged on the surface of the transparent layer 140 according to an array distribution pattern. Of course, steps S4 and S5 can be omitted, and the preparation process of the projection film 100 can be completed by completing step S3. For example, if the transparent material is glue, during step S3, the glue must be evenly applied to the surface of the reflective layer 130 to ensure that, after the glue solidifies, the side of the glue layer facing away from the reflective layer 130 is a flat surface parallel to the surface of the substrate 110.

[0069] The above specific embodiments do not constitute a limitation on the scope of protection of this application. Those skilled in the art will appreciate that various modifications, combinations, sub-combinations, and substitutions may be made based on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application shall be included within the scope of protection of this application.

Claims

1. A projection film, characterized in that: include: substrate; a microlens layer formed on a surface of the substrate; a reflective layer covering a side of the microlens layer facing away from the substrate; wherein the reflective layer has a transmittance greater than zero, and comprises a dielectric film coated on the microlens layer, wherein the difference between the refractive index of the dielectric film and the refractive index of the microlens layer is not less than 0.4; and A transparent layer covers the side of the reflective layer facing away from the microlens layer; wherein the relative relationship between the refractive index of the transparent layer and the refractive index of the microlens layer satisfies a preset condition so that the propagation direction of the transmitted light beam passing through the reflective layer is the same in the transparent layer and the microlens layer.

2. The projection film according to claim 1, wherein The preset condition is that an absolute value of a difference between a refractive index of the transparent layer and a refractive index of the microlens layer is not greater than a predetermined threshold.

3. The projection film according to claim 2, wherein: The predetermined threshold is 0.

15.

4. The projection film according to claim 1, wherein The reflective layer includes a metal film plated on the microlens layer.

5. The projection film according to claim 1, wherein The reflectivity of the reflective layer is 10% to 20%.

6. The projection film according to any one of claims 1 to 5, wherein: The microlens layer includes a plurality of first microlenses, and curved surfaces of the first microlenses are asymmetric about a central axis of the first microlenses in a line perpendicular to the substrate.

7. The projection film according to claim 6, wherein: The curved surface of the first microlens is aspherical.

8. The projection film according to any one of claims 1 to 5, wherein: The side of the transparent layer facing away from the reflective layer is a plane parallel to the plate surface of the substrate.

9. The projection film according to any one of claims 1 to 5, wherein: A plurality of micro-protrusions are formed on a side of the transparent layer facing away from the reflective layer, and a width of the micro-protrusions is no greater than 400 nm.

10. The projection film according to any one of claims 1 to 5, wherein: A plurality of second micro lenses are uniformly distributed on a side of the transparent layer facing away from the reflective layer, and a curvature radius of the second micro lenses is not less than 2 mm.

11. The projection film according to claim 10, wherein: The microlens layer includes a plurality of first microlenses, and the plurality of first microlenses are distributed in an array; And / or, a plurality of the second micro lenses are distributed in an array.

12. The projection film according to claim 1, wherein The reflective layer has a fixed thickness.

13. A projection display assembly, characterized in that: include: projection display panels; as well as The projection film according to any one of claims 1 to 12, wherein the substrate of the projection film is attached to the projection display panel.

14. A method for preparing a projection film, characterized in that: The following steps are involved: Arranging a plurality of first micro lenses on the plate surface of the substrate to form a micro lens layer; A reflective material is coated on a side of the microlens layer facing away from the substrate to form a reflective layer; wherein the reflective layer has a transmittance greater than zero, and the reflective layer comprises a dielectric film coated on the microlens layer, and the difference between the refractive index of the dielectric film and the refractive index of the microlens layer is not less than 0.4; Covering the side of the reflective layer facing away from the microlens layer with a transparent material to form a transparent layer; The relative relationship between the refractive index of the transparent layer and the refractive index of the microlens layer satisfies a preset condition, so that the transmission light beam passing through the reflective layer has the same propagation direction in the transparent layer and the microlens layer.

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