Diffusion element and preparation method thereof, and projection system

Abstract

The present application discloses a diffusion element and a preparation method thereof, and a projection system. The diffusion element comprises a substrate and a plurality of microlenses; the plurality of microlenses are arranged on a side surface of the substrate; wherein the distance from a position farthest from the substrate to a preset axis of at least one microlens is smaller than the distance from the center of a surface of the microlens close to the substrate to the preset axis, and the preset axis is parallel to the central axis of the substrate.

Description

Technical Field

[0001] The present application relates to the field of optical technology, and in particular to a diffusion element and a preparation method thereof, and a projection system. Background Art

[0002] The diffusion element can modulate the incident light to form a more uniform light field as much as possible. Therefore, the diffusion element is widely used in the fields of head-up display systems, laser radar, projection systems, etc. In the head-up display system, the range of the eye box is related to the diffusion angle of the diffusion element. For example, the larger the range of the eye box, the larger the diffusion angle of the required diffusion element. However, when the diffusion angle of the diffusion element is large, the brightness of the eye box will be significantly reduced.

[0003] In order to achieve a large eye box and high brightness, microstructures can be set on both side surfaces of the diffusion element, and the sizes of the microstructures on both sides of the diffusion element are relatively close, which will cause the diffusion element to easily produce moiré fringes, and the sizes of the microstructures on both sides of the diffusion element need to be aligned. The preparation process of the diffusion element is relatively complicated and the cost is high. Summary of the invention

[0004] The embodiments of the present application provide a diffusion element and a preparation method thereof, and a projection system that can at least partially solve at least one of the above-mentioned disadvantages or other disadvantages in the prior art.

[0005] A first aspect of the present application provides a diffusion element, which includes a substrate and a plurality of microlenses; the plurality of microlenses are arranged on a side surface of the substrate; wherein a distance from a position farthest from the substrate to a preset axis of at least one microlens is smaller than a distance from a center of a surface of the microlens close to the substrate to the preset axis, and the preset axis is parallel to a central axis of the substrate.

[0006] According to an exemplary embodiment of the present application, a principal optical axis of an outgoing light ray emitted from at least one microlens is tilted toward a direction close to a preset axis relative to a principal optical axis of an incident light ray.

[0007] According to an exemplary embodiment of the present application, a plurality of microlenses satisfy: |θ1|>|θ2|, wherein θ1 is a deflection angle of a microlens far from a preset axis among at least two adjacent microlenses, and θ2 is a deflection angle of a microlens close to the preset axis among at least two adjacent microlenses, and the deflection angle of a microlens is an angle between a principal optical axis of an outgoing light ray corresponding to the microlens and a principal optical axis of an incident light ray.

[0008] According to an exemplary embodiment of the present application, the microlens includes a light diffusion portion, the light diffusion portion includes a first end away from a preset axis and a second end close to the preset axis; wherein the step height of at least one microlens is greater than 0 μm, and the step height of the microlens is the distance from the second end of the light diffusion portion of the microlens to the first end of another light diffusion portion adjacent to the second end of the light diffusion portion.

[0009] According to an exemplary embodiment of the present application, a difference in absolute value of curvature between the first end and the second end of the light diffusion portion of the plurality of microlenses gradually increases from the preset axis toward the edge of the substrate.

[0010] According to an exemplary embodiment of the present application, the diffusion element also includes a connecting portion, which extends from the second end of the light diffusion portion of one microlens toward a direction close to the substrate, and one side of the connecting portion close to the substrate is connected to the first end of the light diffusion portion of another microlens adjacent to the microlens.

[0011] According to an exemplary embodiment of the present application, a step height of at least one microlens close to a preset axis is equal to 0 μm.

[0012] According to an exemplary embodiment of the present application, a plurality of microlenses are arranged on a side surface of a substrate along a first direction and / or a second direction, wherein the first direction and the second direction intersect and are both parallel to the surface of the substrate on which the microlenses are arranged.

[0013] According to an exemplary embodiment of the present application, in the first direction and / or the second direction, the center of a preset diffusion surface of at least one microlens is closer to the preset axis than the center of a surface of the microlens close to the substrate.

[0014] According to an exemplary embodiment of the present application, in the first direction and / or the second direction, at least two microlenses have different step heights, and at least two microlenses have different absolute values ​​of deflection angles, wherein the deflection angle of the microlens is the angle between the principal optical axis of the outgoing light corresponding to the microlens and the principal optical axis of the incident light.

[0015] According to an exemplary embodiment of the present application, in the first direction and / or the second direction, the height difference of the plurality of microlenses gradually increases from the preset axis to the edge of the substrate, and the absolute value of the deflection angle of the plurality of microlenses gradually increases from the preset axis to the edge of the substrate.

[0016] According to an exemplary embodiment of the present application, in the first direction and / or the second direction, the height differences of the plurality of microlenses are symmetrically distributed or asymmetrically distributed relative to a preset axis; the absolute values ​​of the deflection angles of the plurality of microlenses are symmetrically distributed or asymmetrically distributed relative to the preset axis.

[0017] According to an exemplary embodiment of the present application, the plurality of microlenses satisfy: 0<(|θ1|-|θ2|)×50<FOV, wherein FOV is a preset diffusion angle of the diffusion element.

[0018] According to an exemplary embodiment of the present application, a plurality of microlenses satisfy: H1>H2, wherein H1 is the step height of at least two adjacent microlenses that are far from a preset axis, and H2 is the step height of at least two adjacent microlenses that are close to the preset axis.

[0019] According to an exemplary embodiment of the present application, the microlens satisfies: 0≤H / h≤1, wherein H is the step height of the microlens; h is the sagittal height of the microlens, and the sagittal height of the microlens is the distance from the position farthest from the substrate in the light diffusion part of the microlens to the first end of another light diffusion part adjacent to the second end of the light diffusion part.

[0020] According to an exemplary embodiment of the present application, multiple microlenses satisfy: H1 / h1>H2 / h2, wherein H1 is the step height of at least two adjacent microlenses away from a preset axis, h1 is the sag height of at least two adjacent microlenses away from the preset axis, H2 is the step height of at least two adjacent microlenses close to the preset axis, and h2 is the sag height of at least two adjacent microlenses close to the preset axis.

[0021] According to an exemplary embodiment of the present application, the microlens satisfies: (0.44-0.004×(|α|-8))×|θ|×(L / 20)≤H×1°×1°≤(0.84-0.004×(|α|-8))×|θ|×(L / 20), wherein H is the step height of the microlens; α is the angle between the principal optical axis of the incident light corresponding to the microlens and the preset axis; θ is the deflection angle of the microlens, which is the angle between the principal optical axis of the outgoing light corresponding to the microlens and the principal optical axis of the incident light; and L is the size of the microlens.

[0022] According to an exemplary embodiment of the present application, the microlens satisfies: 0≤H / (|θ|×L)×1°≤0.035, wherein H is the step height of the microlens; θ is the deflection angle of the microlens, which is the angle between the principal optical axis of the outgoing light corresponding to the microlens and the principal optical axis of the incident light; and L is the size of the microlens.

[0023] According to an exemplary embodiment of the present application, the preset diffusion surfaces of the microlenses located at two opposite side edges of the substrate overlap.

[0024] The second aspect of the present application provides a method for preparing a diffusion element, which includes: forming a plurality of microlenses on a side surface of a substrate; and adjusting the plurality of microlenses so that the distance from the position farthest from the substrate to a preset axis of at least one microlens is smaller than the distance from the center of the surface of the microlens close to the substrate to the preset axis, and the preset axis is parallel to the central axis of the substrate.

[0025] The third aspect of the present application provides a projection system, which includes an image generation module, a diffusion element as described in the first aspect of the present application, and a projection module; the image generation module is used to emit image light carrying image information; the diffusion element is used to diffuse the image light to form diffused light; and the projection module is used to project the diffused light.

[0026] The diffusion element provided by the present application can make at least one microlens deflect the diffusion of light toward the center of the substrate by arranging a plurality of microlenses on the surface of one side of the substrate, and the distance from the position farthest from the substrate to the preset axis of at least one microlens is smaller than the distance from the center of the surface close to the substrate of the microlens to the preset axis, so that the diffusion of light by at least one microlens is deflected toward the center of the substrate, and when the diffusion element has a small diffusion angle, the diffusion element is ensured to have a larger diffusion surface and higher brightness, which is conducive to achieving a large eye box and high brightness. In addition, the difficulty and cost of the preparation process of the diffusion element can also be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Other features, purposes and advantages of the embodiments 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, in which:

[0028] Figure 1 A diffusion schematic diagram of a diffusion element in the prior art is shown;

[0029] Figure 2 A schematic structural diagram of a diffusion element in the prior art is shown;

[0030] Figure 3 A schematic diagram of the structure of a microlens in the prior art is shown;

[0031] Figure 4 A schematic diagram of the structure of another diffusion element in the prior art is shown;

[0032] Figure 5 A schematic structural diagram of a diffusion element according to an exemplary embodiment of the present application is shown;

[0033] Figure 6 A diffusion schematic diagram of a diffusion element according to an exemplary embodiment of the present application is shown;

[0034] Figure 7A schematic diagram showing the structure of a microlens according to an exemplary embodiment of the present application is shown;

[0035] Figure 8 shows a top view of a diffusion element according to an exemplary embodiment of the present application;

[0036] Fig. 9 A diffusion schematic diagram of a diffusion element according to an exemplary embodiment of the present application is shown;

[0037] Fig.10 Shows Figure 8 of aa Schematic cross section;

[0038] Fig.11 shows a top view of a diffusion element according to an embodiment of the present application;

[0039] Fig.12 Shows Fig.11 of aa Schematic cross section;

[0040] Fig.13 Shows Fig.11 of bb A schematic cross-sectional view; and

[0041] Fig.14 A schematic flow chart of a method for preparing a diffusion element according to an exemplary embodiment of the present application is shown. DETAILED DESCRIPTION

[0042] In order to better understand the present application, a more detailed description will be made of various aspects of the present application with reference to the accompanying drawings. It should be understood that these detailed descriptions are only descriptions of exemplary embodiments of the present application, and are not intended to limit the scope of the present application in any way. Throughout the specification, the same reference numerals refer to the same elements. The expression "and / or" includes any and all combinations of one or more of the associated listed items.

[0043] It should be noted that in this specification, the expressions of first, second, etc. are only used to distinguish one feature from another feature, and do not represent any limitation on the feature. Therefore, without departing from the teaching of the present application, the first direction discussed below can be referred to as the second direction.

[0044] In the drawings, the thickness, size and shape of each component may be slightly exaggerated for convenience of explanation. The drawings are only examples and are not drawn strictly to scale.

[0045] It should also be understood that the terms "comprising", "including", "having" and / or "provided with", when used in this specification, indicate the presence of stated features, elements and / or components, but do not exclude the presence of one or more other features, elements, components and / or combinations thereof. In addition, the term "exemplarily" is intended to refer to an example or illustration.

[0046] Unless otherwise defined, all terms (including technical and scientific terms) used in this application have the same meaning as commonly understood by those skilled in the art to which this application belongs. It should also be understood that terms (such as those defined in commonly used dictionaries) should be understood to have the same meaning as they have in the context of the relevant technology, and should not be interpreted in an idealized or overly formal sense, unless explicitly defined in this application.

[0047] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in the present 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.

[0048] It should be noted that, hereinafter, the first direction may be referred to as the X direction, the second direction may be referred to as the Y direction, and the third direction may be referred to as the Z direction. The X direction, the Y direction, and the Z direction in each figure show the spatial relationship of the components in the diffusion element. For example, the Z direction is the height direction of the diffusion element, and the X direction and the Y direction are two directions that intersect (e.g., are perpendicular) to each other on a plane that intersects (e.g., is perpendicular) to the height direction. In addition, the X direction, the Y direction, and the Z direction in each figure include not only the direction indicated by the arrow, but also the direction that deviates from the arrow. In other words, the arrows in the X direction, the Y direction, and the Z direction do not have a limiting meaning. The same concept will be used throughout this application to describe the spatial relationship of the components in the diffusion element.

[0049] The head-up display system generally includes an image generation module, a diffusion element, and a projection module. The image generation module can emit image light carrying image information. The diffusion element can diffuse the image light to form diffused light. The projection module can project the diffused light to the eye box area. The eye box area can be the area where the observer's eyes are located and the image output by the head-up display system can be seen.

[0050] The range of the eye box area is related to the diffusion angle of the diffusion element. For example, the larger the diffusion angle of the diffusion element, the larger the range of the eye box area. Figure 1 As shown, the eye box area 250 can be the overlapping area of ​​the diffusion angles of the opposite side edges of the diffusion element 200. The larger the range of the eye box area 250, the larger the required diffusion angle of the diffusion element 200, and the lower the brightness of the eye box.

[0051] Specifically, Figure 2 A schematic structural diagram of the diffusion element 200 is shown. Figure 3 The schematic diagram of the structure of the microlens 220 is shown. The incident light enters the substrate 210 and is diffused by the multiple microlenses 220 on the substrate before being emitted. The absolute value of the curvature of the endpoints on both sides of the light diffusion portion 221 of each microlens 220 is the same, for example, the absolute value of the curvature of the first end A and the second end B of the light diffusion portion 221 is the same. Since the absolute value of the curvature of the first end A and the second end B of the light diffusion portion 221 is the same, the light with the same incident angle is refracted in the same way at the first end A and the second end B of the light diffusion portion 221, that is, the center of the preset diffusion surface 260 of the microlens 220 (for example, the midpoint of the line segment where the endpoints D and E are located) will not be deflected relative to the center of the incident light of the microlens 220 (for example, the midpoint of the line segment where the first end A and the second end B are located). The overlapping area of ​​the preset diffusion surface 260 on the opposite side edges of the diffusion element 200 is the eye box area 250. When the range of the eye box area 250 is large, the larger the diffusion angle of the required diffusion element 200 is, the lower the brightness of the eye box is.

[0052] In order to realize a large eye box and high brightness of the head-up display system, both sides of the substrate 210 in the diffusion element 200 may be provided with microstructures. Figure 4 As shown, one side surface of the substrate 210 is a Fresnel structure 270, and the other side surface is a microlens 220, and the microstructure sizes on both sides of the substrate 210 are relatively close, for example, both are tens of microns, which will cause the diffusion element 200 to easily produce a moiré phenomenon, and the projection screen of the head-up display system will have double images. In addition, the microstructure sizes on both sides of the diffusion element 200 need to be aligned, and the preparation process of the diffusion element 200 is relatively complicated and the cost is relatively high.

[0053] In order to at least partially solve one or more of the above-mentioned problems and other potential problems, the first aspect of the present application proposes a diffusion element. Specifically, a plurality of microlenses are arranged on the surface of one side of a substrate, and at least one of the microlenses deflects the diffusion of light toward the center of the substrate, so as to ensure that the diffusion element has a larger diffusion surface and higher brightness while having a smaller diffusion angle.

[0054] Figure 5 A schematic structural diagram of a diffusion element 200 according to an exemplary embodiment of the present application is shown. Figure 6 A diffusion schematic diagram of a diffusion element 200 according to an exemplary embodiment of the present application is shown. Figure 72 shows a schematic diagram of the structure of a microlens 220 according to an exemplary embodiment of the present application. The diffusion element 200 can be applied to a head-up display system, for example. It should be understood that the diffusion element 200 can also be applied to other optical systems, and the present application does not make any specific limitation on this.

[0055] refer to Figure 5 , Figure 6 and Figure 7 , the diffusion element 200 may include a substrate 210 and a plurality of microlenses 220. The substrate 210 may include a first surface and a second surface that are arranged opposite to each other. The first surface may be, for example, a light incident surface. The second surface may be, for example, a light exit surface. The plurality of microlenses 220 may be arranged on a side surface of the substrate 210, for example, the plurality of microlenses 220 may be arranged on the second surface of the substrate 210.

[0056] The distance from the position farthest from the substrate 210 to the preset axis 240 of at least one microlens 220 may be smaller than the distance from the center of the surface of the microlens 220 close to the substrate 210 to the preset axis 240, wherein the preset axis 240 may be parallel to the central axis of the substrate 210. In other words, the preset axis 240 may be the central axis of the substrate 210, or the preset axis 240 may be spaced a certain distance from the central axis of the substrate 210.

[0057] By arranging a plurality of microlenses 220 on one side surface of the substrate 210, and the distance from the position farthest from the substrate (for example, vertex C) to the preset axis 240 of at least one microlens 220 is smaller than the distance from the center of the surface close to the substrate of the microlens 220 to the preset axis 240, the diffusion of light by the microlens 220 can be deflected toward the center of the substrate, and when the diffusion element 200 has a small diffusion angle, the diffusion element 200 is ensured to have a larger diffusion surface and higher brightness, which is conducive to realizing a large eye box and high brightness of the projection system including the diffusion element. In addition, the difficulty and cost of the preparation process of the diffusion element 200 can also be reduced.

[0058] In an exemplary embodiment, the substrate 210 may be a thin plate-like structure, and its material may be a transparent material.

[0059] In an exemplary embodiment, the incident light may enter the substrate 210 through the first surface of the substrate, and be diffused by the plurality of microlenses 220 on the second surface of the substrate before being emitted. For at least one microlens 220, the main optical axis II of the outgoing light emitted from the microlens 220 may be deflected relative to the main optical axis I of the incident light. For example, the main optical axis II of the outgoing light emitted from the microlens 220 is inclined relative to the main optical axis I of the incident light toward the direction close to the preset axis 240. In other words, there is an angle between the main optical axis II of the outgoing light corresponding to the microlens 220 and the main optical axis I of the incident light. The angle between the main optical axis II of the outgoing light corresponding to the microlens 220 and the main optical axis I of the incident light may be referred to as the deflection angle θ of the microlens 220 (e.g., Fig. 9 ).

[0060] By making the main optical axis II of the outgoing light emitted by at least one microlens 220 tilt toward the direction close to the preset axis 240 relative to the main optical axis I of the incident light, the diffusion of light by the microlens 220 can be deflected toward the center of the substrate, and when the diffusion element 200 has a small diffusion angle, the diffusion element 200 is ensured to have a large diffusion surface and high brightness, which is conducive to achieving a large eye box and high brightness of the projection system including the diffusion element. In addition, the difficulty and cost of the preparation process of the diffusion element 200 can also be reduced.

[0061] In an exemplary embodiment, for at least a portion of the microlenses 220, the principal optical axis II of the outgoing light emitted from the microlenses 220 may not be deflected relative to the principal optical axis I of the incident light, in other words, the deflection angle θ of the microlenses 220 may be 0°. For example, the deflection angle θ of the microlenses 220 disposed in the central region of the substrate may be 0°.

[0062] In an exemplary embodiment, the plurality of microlenses 220 may satisfy: |θ1|>|θ2|, wherein θ1 is the deflection angle of the microlens far from the preset axis 240 among at least two adjacent microlenses 220, and θ2 is the deflection angle of the microlens close to the preset axis 240 among at least two adjacent microlenses 220. It should be understood that the concept of the deflection angle of the microlens in this document is the same, and the deflection angle of the microlens will not be described in detail below.

[0063] By making the microlenses 220 near the edge of the substrate deflect the diffusion of light toward the center of the substrate, when the diffusion element 200 has a small diffusion angle, it can ensure that the diffusion element 200 has a larger diffusion surface and higher brightness, which is conducive to achieving a large eye box and high brightness of the projection system including the diffusion element. In addition, at least two adjacent microlenses 220 can have different structural sizes, which is conducive to reducing the moiré fringe phenomenon of the diffusion element 200, improving the imaging quality and uniformity of the diffusion element 200, and reducing the difficulty and cost of the preparation process of the diffusion element 200.

[0064] In an exemplary embodiment, reference Fig.10 , Fig.12 and Fig.13 Any two adjacent microlenses 220 of the plurality of microlenses may include a first microlens 2201 and a second microlens 2202. The first microlens 2201 may be far from the preset axis 240, and the second microlens 2202 may be close to the preset axis 240. The deflection angle θ1 of the first microlens 2201 and the deflection angle θ2 of the second microlens 2202 may satisfy: |θ1|≥|θ2|. When the absolute values ​​of the deflection angles of the first microlens 2201 and the second microlens 2202 are the same, the first microlens 2201 and the second microlens 2202 may be disposed in the central area of ​​the substrate, and the deflection angles of the first microlens 2201 and the second microlens 2202 may be 0°.

[0065] In an exemplary embodiment, reference Figure 7 , Fig.10 , Fig.12 and Fig.13 , the microlens 220 may include a light diffusion portion 221. The light diffusion portion 221 may be a surface of the microlens 220 away from the substrate, and the surface may be, for example, a curved surface. The light diffusion portion 221 may include a first end A and a second end B, the first end A may be away from the preset axis 240, and the second end B may be close to the preset axis 240. The absolute value of the curvature of the first end A of the light diffusion portion 221 may be less than or equal to the absolute value of the curvature of the second end B of the light diffusion portion 221.

[0066] The absolute value of the deflection angle of the microlens 220 may be positively correlated with the difference in absolute values ​​of the curvatures of the first end A and the second end B of the light diffuser 221. In other words, the greater the difference in absolute values ​​of the curvatures of the first end A and the second end B of the light diffuser 221, the greater the deflection angle of the microlens 220; the smaller the difference in absolute values ​​of the curvatures of the first end A and the second end B of the light diffuser 221, the smaller the deflection angle of the microlens 220. When the difference in absolute values ​​of the curvatures of the first end A and the second end B of the light diffuser 221 is 0, the deflection angle of the microlens 220 may be 0°.

[0067] In an exemplary embodiment, the difference in the absolute value of the curvature of the first end A and the second end B of the light diffusion part 221 of the plurality of microlenses gradually increases from the preset axis 240 to the edge of the substrate 210. By making the difference in the absolute value of the curvature of the first end A and the second end B of the light diffusion part 221 of the plurality of microlenses gradually increase from the preset axis 240 to the edge of the substrate 210, it is possible to ensure that the microlenses 220 close to the edge of the substrate produce a greater deflection for the diffusion of light, and the microlenses 220 close to the center of the substrate produce a smaller deflection or no deflection for the diffusion of light. When the diffusion element 200 has a smaller diffusion angle, it is ensured that the diffusion element 200 has a larger diffusion surface and higher brightness, which is conducive to realizing a large eye box and high brightness of the projection system including the diffusion element. In addition, different microlenses 220 can also have different structural sizes, which is conducive to reducing the moiré fringe phenomenon of the diffusion element 200, improving the imaging quality and uniformity of the diffusion element 200, and reducing the difficulty and cost of the preparation process of the diffusion element 200.

[0068] In an exemplary embodiment, the step height of at least one microlens 220 may be greater than 0 μm. The step height H of the microlens 220 may be the distance from the second end B of the light diffusion portion of the microlens 220 to the first end A of another light diffusion portion 221 adjacent to the second end of the light diffusion portion (for example, the distance in the third direction). It should be understood that the concept of the step height of the microlens in this article is the same, and the step height of the microlens will not be repeated below.

[0069] By controlling the height difference of at least one microlens 220 to be greater than 0 μm, the light diffusion of the microlens 220 can be deflected toward the center of the substrate 210. When the diffusion element 200 has a smaller diffusion angle, the diffusion element 200 is ensured to have a larger diffusion surface and higher brightness, which is conducive to achieving a large eye box and high brightness of the projection system including the diffusion element.

[0070] In an exemplary embodiment, reference Fig.10 , Fig.12 and Fig.13 , the step height of at least one microlens 220 near the preset axis 240 may be equal to 0 μm. In other words, the second end B of the light diffusion portion 221 of at least one microlens near the preset axis 240 may be connected to the first end A of the light diffusion portion 221 of another microlens adjacent to the microlens. For example, the second end B of the light diffusion portion 221 of the first microlens 2201 may be connected to the first end A of the light diffusion portion 221 of the second microlens 2202, and the step height H of the first microlens 2201 may be equal to 0 μm.

[0071] In an exemplary embodiment, reference Fig.10 , Fig.12 and Fig.13, the diffusion element 200 may further include a connection portion 230. The connection portion 230 may extend from the second end B of the light diffusion portion 221 of a microlens toward the direction close to the substrate 210, and the side of the connection portion 230 close to the substrate 210 is connected to the first end A of the light diffusion portion 221 of another microlens adjacent to the microlens. In other words, the step height H of the microlens 220 may be greater than 0 μm. For example, the second end B of the light diffusion portion 221 of the first microlens 2201 may be connected to the first end A of the light diffusion portion 221 of the second microlens 2202 through the connection portion 230. The step height H of the first microlens 2201 may be greater than 0 μm.

[0072] In an exemplary embodiment, a plurality of microlenses 220 may be disposed on a side surface of the substrate 210 along a first direction and / or a second direction, wherein the first direction and the second direction intersect and are both parallel to the surface of the substrate 210 on which the microlenses 220 are disposed. A plurality of microlenses 220 may be disposed on the second surface of the substrate 210 along the first direction; or, a plurality of microlenses 220 may be disposed on the second surface of the substrate 210 along the second direction; or, a plurality of microlenses 220 may be disposed in an array along the first direction and the second direction on the second surface of the substrate 210. For example, a plurality of microlenses 220 may be disposed on the second surface of the substrate 210 in a manner of, for example, m rows×n columns, the first direction may be, for example, a row direction, and the second direction may be, for example, a column direction.

[0073] In an exemplary embodiment, in the first direction and / or the second direction, the principal optical axis II of the outgoing light emitted from at least one microlens 220 may be deflected relative to the principal optical axis I of the incident light, and accordingly, the center of the preset diffusion surface 260 of the microlens 220 may be deflected relative to the center of the surface of the microlens 220 close to the substrate. In other words, the center of the preset diffusion surface 260 of at least one microlens 220 (for example, a microlens close to the edge of the substrate) is closer to the preset axis 240 than the center of the surface of the microlens 220 close to the substrate. The absolute value of the deflection angle θ of at least one microlens 220 may be greater than 0°.

[0074] refer to Figure 7 , the absolute values ​​of the curvatures of the first end A and the second end B of the light diffusion portion 221 are different, so the light rays with the same incident angle are refracted differently at the first end A and the second end B of the light diffusion portion 221, and the center of the preset diffusion surface 260 of the microlens 220 (for example, the midpoint of the line segment where the end points D and E are located) is deflected relative to the center of the surface of the microlens 220 close to the substrate. The overlapped area of ​​the preset diffusion surface 260 of the microlens located at the opposite side edges of the substrate can be the eye box area 250 (such as Figure 6). By controlling the center of the preset diffusion surface 260 of the microlens 220 near the edge of the substrate to be deflected relative to the center of the surface of the microlens 220 near the substrate, when the diffusion element 200 has a smaller diffusion angle, it is possible to ensure that the diffusion element 200 has a larger diffusion surface and higher brightness, thereby facilitating the realization of a large eye box and high brightness of the projection system including the diffusion element.

[0075] In an exemplary embodiment, reference Fig.10 , Fig.12 and Fig.13 In the first direction and / or the second direction, at least two microlenses 220 have different step heights H. For example, at least two adjacent microlenses 220 have different step heights H. By controlling at least two adjacent microlenses 220 to have different step heights, at least two adjacent microlenses 220 can have different structural sizes, which is beneficial to reducing the moire fringe phenomenon of the diffusion element 200 and improving the imaging quality and uniformity of the diffusion element 200.

[0076] In an exemplary embodiment, in the first direction and / or the second direction, the absolute values ​​of the deflection angles θ of at least two microlenses 220 are different. For example, the absolute values ​​of the deflection angles θ of at least two adjacent microlenses 220 are different. By controlling at least two adjacent microlenses 220 to have different absolute values ​​of deflection angles, at least two adjacent microlenses 220 can have different structural sizes, which is beneficial to reducing the moire fringe phenomenon of the diffusion element 200 and improving the imaging quality and uniformity of the diffusion element 200.

[0077] In an exemplary embodiment, reference Fig.10 , Fig.12 and Fig.13 , the plurality of microlenses 220 may satisfy: H1>H2, wherein H1 is the step height of at least two adjacent microlenses 220 that are away from the preset axis 240, and H2 is the step height of at least two adjacent microlenses 220 that are close to the preset axis 240. For example, the step height H1 of the first microlens 2201 may be greater than the step height H2 of the second microlens 2202.

[0078] The step height of the microlens 220 may correspond to the absolute value of the deflection angle of the microlens 220 one by one. That is, when the step height of the microlens 220 is different, the absolute value of the deflection angle of the microlens 220 is different. The absolute value of the deflection angle of the microlens 220 may be positively correlated with the step height of the microlens 220. By making at least two adjacent microlenses 220 have different step heights, and compared with the microlens 220 near the center of the substrate, the microlens 220 near the edge of the substrate has a larger step height, the microlens 220 near the edge of the substrate can produce a larger deflection for the diffusion of light, and when the diffusion element 200 has a smaller diffusion angle, it is ensured that the diffusion element 200 has a larger diffusion surface and higher brightness, which is conducive to realizing a large eye box and high brightness of the projection system including the diffusion element.

[0079] In an exemplary embodiment, reference Fig.10 , Fig.12 and Fig.13 , the microlens 220 can satisfy: 0≤H / h≤1, where H is the step height of the microlens 220; h is the sag of the microlens 220, and the sag of the microlens 220 is the distance from the position farthest from the substrate (e.g., vertex C) in the light diffusion part 221 of the microlens to the first end A of another light diffusion part 221 adjacent to the second end of the light diffusion part (e.g., the distance in the third direction). By constraining the ratio of the step height to the sag of the microlens 220 within the range of 0 to 1, it is helpful to achieve a large eye box and high brightness of the projection system including the diffusion element. It should be understood that the concept of the sag of the microlens in this article is the same, and the sag of the microlens will not be repeated below.

[0080] In an exemplary embodiment, reference Fig.10 , Fig.12 and Fig.13 , the plurality of microlenses 220 may satisfy: H1 / h1>H2 / h2, wherein H1 is the step height of the microlens of at least two adjacent microlenses 220 that is away from the preset axis 240, h1 is the sag height of the microlens of at least two adjacent microlenses 220 that is away from the preset axis 240, H2 is the step height of the microlens of at least two adjacent microlenses 220 that is close to the preset axis 240, and h2 is the sag height of the microlens of at least two adjacent microlenses 220 that is close to the preset axis 240.

[0081] By controlling the ratio of the step height to the sagittal height of at least two adjacent microlenses 220 to be different, and compared with the microlens 220 near the center of the substrate, the microlens 220 near the edge of the substrate has a larger ratio of the step height to the sagittal height, the microlens 220 near the edge of the substrate can produce a larger deflection for the diffusion of light. When the diffusion element 200 has a smaller diffusion angle, the diffusion element 200 is ensured to have a larger diffusion surface and higher brightness, which is conducive to achieving a large eye box and high brightness of the projection system including the diffusion element.

[0082] In an exemplary embodiment, reference Fig.10 , Fig.12 and Fig.13 In the first direction and / or the second direction, the height difference of the multiple microlenses 220 can gradually increase from the preset axis 240 to the edge of the substrate 210, and the absolute value of the deflection angle of the multiple microlenses 220 can gradually increase from the preset axis 240 to the edge of the substrate 210.

[0083] By controlling the step height of the plurality of microlenses 220 to gradually change from the preset axis 240 to the edge of the substrate, the absolute value of the deflection angle of the plurality of microlenses 220 can be gradually changed from the preset axis 240 to the edge of the substrate, thereby ensuring that the microlenses 220 close to the edge of the substrate produce a greater deflection for the diffusion of light, and the microlenses 220 close to the center of the substrate produce a smaller deflection or no deflection for the diffusion of light. When the diffusion element 200 has a smaller diffusion angle, it is ensured that the diffusion element 200 has a larger diffusion surface and higher brightness, which is conducive to realizing a large eye box and high brightness of the projection system including the diffusion element. In addition, when the step height of the plurality of microlenses 220 in the first direction and the second direction is gradually changed at the same time, the microlenses 220 close to the edge of the substrate in the two directions can produce a greater deflection for the diffusion of light, reduce the diffusion angle of the diffusion element 200 in the two directions, and ensure that the diffusion element 200 has a larger diffusion surface and higher brightness in the two directions.

[0084] In an exemplary embodiment, reference Fig.10 In the first direction and / or the second direction, the height differences of the multiple microlenses 220 can be distributed symmetrically relative to the preset axis 240, and the absolute values ​​of the deflection angles of the multiple microlenses 220 can be distributed symmetrically relative to the preset axis 240.

[0085] In an exemplary embodiment, reference Fig.12 and Fig.13 In the first direction and / or the second direction, the height differences of the multiple microlenses 220 may be distributed asymmetrically relative to the preset axis 240 , and the absolute values ​​of the deflection angles of the multiple microlenses 220 may be distributed asymmetrically relative to the preset axis 240 .

[0086] In an exemplary embodiment, the plurality of microlenses 220 may satisfy: 0<(|θ1|-|θ2|)×50<FOV, wherein θ1 is the deflection angle of the microlens of at least two adjacent microlenses 220 that is away from the preset axis 240, θ2 is the deflection angle of the microlens of at least two adjacent microlenses 220 that is close to the preset axis 240, and FOV is the preset diffusion angle of the diffusion element 200.

[0087] By making at least two adjacent microlenses 220 have different deflection angles, and compared with the microlens 220 close to the center of the substrate, the microlens 220 close to the edge of the substrate has a larger deflection angle, the microlens 220 close to the edge of the substrate can produce a larger deflection on the diffusion of light. When the diffusion element 200 has a smaller diffusion angle, it is ensured that the diffusion element 200 has a larger diffusion surface and higher brightness, which is conducive to realizing a large eye box and high brightness of the projection system including the diffusion element. At the same time, the structures and sizes of the two adjacent microlenses 220 are different, thereby suppressing the moire fringe phenomenon of the diffusion element 200, improving the imaging quality and uniformity of the diffusion element 200, and reducing the cost.

[0088] In an exemplary embodiment, the microlens 220 may satisfy: (0.44-0.004×(|α|-8))×|θ|×(L / 20)≤H×1°×1°≤(0.84-0.004×(|α|-8))×|θ|×(L / 20), wherein H is the step height of the microlens 220; α is the angle between the principal optical axis I of the incident light corresponding to the microlens 220 and the preset axis 240; θ is the deflection angle of the microlens 220; and L is the size of the microlens 220. The size of the microlens 220 may be the size of the microlens 220 in the first direction or the second direction. By constraining the step height of the microlens 220 within the above range, when the microlens 220 has an appropriate deflection angle, the diffraction effect of the microlens 220 can be suppressed, which is conducive to ensuring that the projection system including the diffusion element achieves a large eye box and high brightness, and improves the imaging quality of the projection system, for example, the projection screen of the projection system has no rainbow stripes.

[0089] In an exemplary embodiment, the microlens 220 may satisfy: 0≤H / (|θ|×L)×1°≤0.035, wherein H is the step height of the microlens 220; θ is the deflection angle of the microlens 220; and L is the size of the microlens 220. The size of the microlens 220 may be the size of the microlens 220 in the first direction or the second direction. As an example, 0.0015≤H / (|θ|×L)×1°≤0.035. When the size of the microlens 220 is a fixed value, the absolute value of the deflection angle of the microlens 220 may be positively correlated with the step height of the microlens 220. When the size of the microlens 220 is randomly distributed, the absolute value of the deflection angle of the microlens 220 may be positively correlated with the ratio of the step height to the size of the microlens 220. By controlling the above conditional expression, when the microlens 220 has an appropriate deflection angle, the diffraction effect of the microlens 220 can be suppressed, which is beneficial to ensure that the projection system including the diffusion element achieves a large eye box and high brightness, and improves the imaging quality of the projection system, for example, the projection screen of the projection system has no rainbow stripes.

[0090] In an exemplary embodiment, reference Figure 6 In the first direction and / or the second direction, the preset diffusion surfaces 260 of the microlenses 220 located at the two opposite edges of the substrate are substantially overlapped, for example, the overlap area of ​​the preset diffusion surfaces 260 of the microlenses 220 located at the two opposite edges of the substrate is approximately more than 95% of the area of ​​the preset diffusion surfaces 260. By controlling the diffusion of the microlenses at the two opposite edges of the substrate and deflecting them toward the center of the substrate at the same time, it is possible to reduce the waste of light, and when the diffusion element 200 has a small diffusion angle, it is ensured that the diffusion element 200 has a larger diffusion surface and higher brightness, which is conducive to achieving a large eye box and high brightness of the projection system including the diffusion element.

[0091] A specific embodiment of the diffusion element 200 applicable to the above-mentioned embodiment is further described below. Example 1

[0092] Figure 8 A top view of a diffusion element 200 according to Embodiment 1 of the present application is shown. Fig. 9 A diffusion schematic diagram of the diffusion element 200 according to Embodiment 1 of the present application is shown. Fig.10 Shows Figure 8 of aa Schematic cross section.

[0093] refer to Figures 8 to 10, the diffusion element 200 may include a substrate 210 and a plurality of microlenses 220. The plurality of microlenses 220 may be arranged in an array on the second surface of the substrate 210 along the first direction and the second direction. The size of the diffusion element 200 in the first direction is 100 mm, and the size of the diffusion element 200 in the second direction is 40 mm. The preset diffusion angle FOV1 of the diffusion element 200 in the first direction is 20°, and the preset diffusion angle FOV2 of the diffusion element 200 in the second direction is 10°. The size of the microlens 220 in the first direction and the second direction is 20 μm.

[0094] In the first direction, the step heights of the plurality of microlenses 220 may be symmetrically distributed with respect to the preset axis 240, and the absolute values ​​of the deflection angles of the plurality of microlenses 220 may be symmetrically distributed with respect to the preset axis 240. In addition, in the first direction, the step heights of the plurality of microlenses 220 may gradually increase from the preset axis 240 to the edge of the substrate 210, and the absolute values ​​of the deflection angles of the plurality of microlenses 220 may gradually increase from the preset axis 240 to the edge of the substrate 210. The preset axis 240 may be the central axis of the substrate 210. The difference in the absolute values ​​of the deflection angles of two adjacent microlenses 220 may be less than or equal to 0.1°.

[0095] Table 1 shows the θ, H and H / h of the microlenses corresponding to different α values. It should be understood that there may be several microlenses between the microlenses corresponding to the different α values ​​shown in Table 1, for example, there may be several microlenses between the microlenses corresponding to α=-8° and the microlenses corresponding to α=-4°. As shown in Table 1, the absolute value of the angle α between the principal optical axis I of the incident light corresponding to the microlens and the preset axis 240 gradually changes from the edge of the substrate to the center of the substrate, for example, |α| has a maximum value at the edge of the substrate, for example, it may be 16°, and |α| has a minimum value at the center of the substrate, for example, it may be 0°. The absolute value of the deflection angle θ of the microlens and the height difference H of the microlens gradually change from the edge of the substrate to the center of the substrate, for example, |θ| and H have a maximum value at the edge of the substrate, for example, |θ|=3.5°, H=1.778μm; |θ| and H have a minimum value at the center of the substrate, for example, |θ|=0°, H=0μm.

[0096] Table 1

[0097] Example 2

[0098] Fig.11 A top view of a diffusion element 200 according to Embodiment 2 of the present application is shown. Fig.12 Shows Fig.11 of a- a Schematic cross section. Fig.13 Shows Fig.11 of bb Schematic cross section.

[0099] refer to Figures 11 to 13 , the diffusion element 200 may include a substrate 210 and a plurality of microlenses 220. The plurality of microlenses 220 may be arranged in an array on the second surface of the substrate 210 along the first direction and the second direction. The size of the diffusion element 200 in the first direction is 100 mm, and the size of the diffusion element 200 in the second direction is 45 mm. The preset diffusion angle FOV1 of the diffusion element 200 in the first direction is 23°, and the preset diffusion angle FOV2 of the diffusion element 200 in the second direction is 7°. The size of the microlens 220 in the first direction and the second direction is 20 μm.

[0100] In the first direction and the second direction, the height difference of the multiple microlenses 220 can be asymmetrically distributed relative to the preset axis 240, and the absolute value of the deflection angle of the multiple microlenses 220 can be asymmetrically distributed relative to the preset axis 240. In addition, in the first direction, the height difference of the multiple microlenses 220 can gradually increase from the preset axis 240 to the edge of the substrate 210, and the absolute value of the deflection angle of the multiple microlenses 220 can gradually increase from the preset axis 240 to the edge of the substrate 210. The preset axis 240 can be spaced a certain distance from the central axis of the substrate 210. The difference in the absolute value of the deflection angle of two adjacent microlenses 220 can be less than or equal to 0.1°. For example, the difference in the absolute value of the deflection angle of two adjacent microlenses 220 in the first direction can be less than or equal to 0.06°. The difference in the absolute value of the deflection angle of two adjacent microlenses 220 in the second direction can be less than or equal to 0.03°.

[0101] Table 2 shows θ, H and H / h of the microlenses corresponding to different α values ​​in the first direction. It should be understood that there may be several microlenses between the microlenses corresponding to the different α values ​​shown in Table 2, for example, there may be several microlenses between the microlenses corresponding to α=-5° and the microlenses corresponding to α=-3°. As shown in Table 2, in the first direction, the angle α between the principal optical axis I of the incident light corresponding to the microlens and the preset axis 240 changes from one side edge of the substrate to the other side edge of the substrate, for example, from -10° to 12°; θ changes from one side edge of the substrate to the other side edge of the substrate, for example, from -7° to 2.5°.

[0102] Table 2

[0103]

[0104] Table 3 shows θ, H and H / h of the microlenses corresponding to different α values ​​in the second direction. It should be understood that there may be several microlenses between the microlenses corresponding to the different α values ​​shown in Table 3, for example, there may be several microlenses between the microlenses corresponding to α=-20° and the microlenses corresponding to α=-18°. As shown in Table 3, in the second direction, the angle α between the principal optical axis I of the incident light corresponding to the microlens and the preset axis 240 changes from one side edge of the substrate to the other side edge of the substrate, for example, from -20° to -5°; θ changes from one side edge of the substrate to the other side edge of the substrate, for example, from -2° to 11°.

[0105] Table 3

[0106]

[0107] The second aspect of the present application provides a method 1000 for preparing a diffusion element. The diffusion element 200 as described in the first aspect of the present application can be formed by using the preparation method 1000.

[0108] Fig.14 FIG. 1 is a schematic flow chart of a method 1000 for preparing a diffusion element according to an exemplary embodiment of the present application. Fig.14 , the preparation method 1000 may include the following steps:

[0109] S100, forming a plurality of micro lenses on a surface of one side of the substrate; and

[0110] S200, adjusting a plurality of microlenses so that a distance from a position farthest from the substrate to a preset axis of at least one microlens is smaller than a distance from a center of a surface of the microlens close to the substrate to the preset axis, and the preset axis is parallel to a central axis of the substrate.

[0111] By arranging a plurality of microlenses on one side surface of the substrate, and the distance from the position farthest from the substrate (for example, vertex C) to the preset axis of at least one microlens is smaller than the distance from the center of the surface close to the substrate of the microlens to the preset axis, the diffusion of light by the microlens can be deflected toward the center of the substrate, and when the diffusion element has a small diffusion angle, the diffusion element is ensured to have a larger diffusion surface and higher brightness, thereby facilitating the realization of a large eye box and high brightness of a projection system including the diffusion element. In addition, the difficulty and cost of the preparation process of the diffusion element can be reduced.

[0112] The steps S100 and S200 of the exemplary embodiment of the present application are exemplarily described below.

[0113] In step S100 , a plurality of micro lenses are formed on a surface of one side of the substrate.

[0114] In an exemplary embodiment, the substrate may include a first surface and a second surface that are arranged opposite to each other. The first surface may be, for example, a light incident surface. The second surface may be, for example, a light exit surface. A light diffusion portion having a plurality of microlenses is formed on a side surface (e.g., the second surface) of the substrate, and the light diffusion portion may be, for example, a curved surface. The light diffusion portion may include a first end A and a second end B, the first end A may be away from a preset axis, and the second end B may be close to the preset axis. The absolute value of the curvature of the first end A may be less than or equal to the absolute value of the curvature of the second end B.

[0115] In an exemplary embodiment, a plurality of microlenses may be disposed on a side surface of the substrate along a first direction and / or a second direction, wherein the first direction and the second direction intersect and are both parallel to the surface of the substrate on which the microlenses are disposed. Specifically, a plurality of microlenses may be disposed on the second surface of the substrate along the first direction; or, a plurality of microlenses may be disposed on the second surface of the substrate along the second direction; or, a plurality of microlenses may be disposed on the second surface of the substrate in an array along the first direction and the second direction. For example, a plurality of microlenses may be disposed on the second surface of the substrate in an m-row×n-column manner, the first direction may be, for example, a row direction, and the second direction may be, for example, a column direction.

[0116] After forming a plurality of microlenses, the plurality of microlenses are adjusted in step S200 so that a distance from a position farthest from the substrate to a preset axis of at least one microlens is smaller than a distance from a center of a surface of the microlens close to the substrate to the preset axis, and the preset axis is parallel to a central axis of the substrate.

[0117] In an exemplary embodiment, the light diffusion portions of the plurality of microlenses are adjusted, for example, the curvatures of the first end A and the second end B of the light diffusion portion of at least one microlens are adjusted so that a distance from a position farthest from the substrate to a preset axis of at least one microlens is smaller than a distance from a center of a surface of the microlens close to the substrate to the preset axis.

[0118] By controlling the distance from the position farthest from the substrate (for example, vertex C) to the preset axis of at least one microlens to be smaller than the distance from the center of the surface of the microlens close to the substrate to the preset axis, the diffusion of light by the microlens can be deflected toward the center of the substrate, and when the diffusion element has a small diffusion angle, the diffusion element is ensured to have a larger diffusion surface and higher brightness, which is conducive to realizing a large eye box and high brightness of the projection system including the diffusion element. In addition, the difficulty and cost of the preparation process of the diffusion element can be reduced.

[0119] In an exemplary embodiment, the preparation method 1000 may further include: adjusting the light diffusion portions of the plurality of microlenses, for example, adjusting the curvatures of the first end A and the second end B of the light diffusion portion of at least one microlens, so that the principal optical axis II of the outgoing light emitted from the microlens is inclined relative to the principal optical axis I of the incident light in a direction close to a preset axis. In other words, there is an angle between the principal optical axis II of the outgoing light corresponding to the microlens and the principal optical axis I of the incident light, and the angle between the principal optical axis II of the outgoing light corresponding to the microlens and the principal optical axis I of the incident light can be called the deflection angle θ of the microlens.

[0120] By making the main optical axis II of the outgoing light emitted by at least one microlens tilt in a direction close to the preset axis relative to the main optical axis I of the incident light, the diffusion of light by the microlens can be deflected toward the center of the substrate, and when the diffusion element has a small diffusion angle, the diffusion element is ensured to have a large diffusion surface and high brightness, which is conducive to achieving a large eye box and high brightness of the projection system including the diffusion element. In addition, the difficulty and cost of the preparation process of the diffusion element can be reduced.

[0121] In an exemplary embodiment, the preparation method 1000 may further include: adjusting the light diffusion part of the plurality of microlenses, for example, adjusting the curvature of the first end A and the second end B of the light diffusion part of at least two adjacent microlenses, so that the plurality of microlenses can satisfy: |θ1|>|θ2|, wherein θ1 is the deflection angle of the microlens far from the preset axis among at least two adjacent microlenses, and θ2 is the deflection angle of the microlens close to the preset axis among at least two adjacent microlenses. The absolute value of the curvature of the first end A of the light diffusion part may be less than or equal to the absolute value of the curvature of the second end B of the light diffusion part.

[0122] The absolute value of the deflection angle of the microlens may be positively correlated with the difference in absolute values ​​of the curvatures of the first end A and the second end B of the light diffuser. In other words, the greater the difference in absolute values ​​of the curvatures of the first end A and the second end B of the light diffuser, the greater the deflection angle of the microlens; the smaller the difference in absolute values ​​of the curvatures of the first end A and the second end B of the light diffuser, the smaller the deflection angle of the microlens. When the difference in absolute values ​​of the curvatures of the first end A and the second end B of the light diffuser is 0, the deflection angle of the microlens may be 0°.

[0123] By controlling multiple microlenses to satisfy |θ1|>|θ2|, the microlenses close to the edge of the substrate can be made to deflect the diffusion of light toward the center of the substrate, and when the diffusion element has a small diffusion angle, the diffusion element can be ensured to have a larger diffusion surface and higher brightness. In addition, at least two adjacent microlenses can have different structural sizes, which is conducive to reducing the moiré fringe phenomenon of the diffusion element, improving the imaging quality and uniformity of the diffusion element, and reducing the difficulty and cost of the preparation process of the diffusion element.

[0124] In an exemplary embodiment, the manufacturing method 1000 may further include: connecting the second end B of the light diffusion portion of one microlens to the first end A of the light diffusion portion of another microlens adjacent to the microlens. In other words, the step height of the microlens may be 0 μm.

[0125] In an exemplary embodiment, the preparation method 1000 may further include: forming a connecting portion. The connecting portion may extend from the second end B of the light diffusion portion of a microlens toward a direction close to the substrate, and a side of the connecting portion close to the substrate is connected to a first end A of the light diffusion portion of another microlens adjacent to the microlens. In other words, the step height of the microlens may be greater than 0 μm.

[0126] In an exemplary embodiment, the preparation method 1000 may further include: adjusting the light diffusion part of the plurality of microlenses, for example, adjusting the curvature of the first end A and the second end B of the light diffusion part of at least one microlens in the first direction and / or the second direction, and making the main optical axis II of the outgoing light emitted from at least one microlens deflect relative to the main optical axis I of the incident light, and accordingly, the center of the preset diffusion surface of the microlens may be deflected relative to the center of the surface of the microlens close to the substrate. In other words, the center of the preset diffusion surface of at least one microlens (for example, a microlens close to the edge of the substrate) is closer to the preset axis than the center of the surface of the microlens close to the substrate. The absolute value of the deflection angle θ of at least one microlens may be greater than 0°. The overlapping area of ​​the preset diffusion surface of the microlenses located at the opposite side edges of the substrate may be an eye box area. By controlling the center of the preset diffusion surface of the microlens close to the edge of the substrate to deflect relative to the center of the surface of the microlens close to the substrate, when the diffusion element has a smaller diffusion angle, it is possible to ensure that the diffusion element has a larger diffusion surface and higher brightness, thereby facilitating the realization of a large eye box and high brightness of a projection system including the diffusion element.

[0127] In an exemplary embodiment, the preparation method 1000 may further include: adjusting the light diffusion part of the plurality of microlenses, for example, adjusting the curvature of the first end A and the second end B of the light diffusion part of at least two adjacent microlenses, and making the absolute values ​​of the deflection angles of at least two microlenses different in the first direction and / or the second direction. By controlling at least two adjacent microlenses to have different absolute values ​​of deflection angles, at least two adjacent microlenses can have different structural sizes, which is conducive to reducing the moiré fringe phenomenon of the diffusion element and improving the imaging quality and uniformity of the diffusion element.

[0128] In an exemplary embodiment, the preparation method 1000 may further include: adjusting the light diffusion parts of the plurality of microlenses, for example, adjusting the light diffusion parts of at least two adjacent microlenses, and making the step heights of the at least two microlenses different in the first direction and / or the second direction. By controlling at least two adjacent microlenses to have different step heights, at least two adjacent microlenses can have different structural sizes, which is conducive to reducing the moiré fringe phenomenon of the diffusion element and improving the imaging quality and uniformity of the diffusion element.

[0129] In an exemplary embodiment, the preparation method 1000 may further include: adjusting the light diffusion part of the plurality of microlenses, and making the plurality of microlenses satisfy: H1>H2, wherein H1 is the step height of the microlens far from the preset axis among at least two adjacent microlenses, and H2 is the step height of the microlens close to the preset axis among at least two adjacent microlenses. By making at least two adjacent microlenses have different step heights, and compared with the microlens close to the center of the substrate, the microlens close to the edge of the substrate has a larger step height, the microlens close to the edge of the substrate can produce a greater deflection on the diffusion of light, and when the diffusion element has a smaller diffusion angle, it is ensured that the diffusion element has a larger diffusion surface and higher brightness.

[0130] In an exemplary embodiment, the preparation method 1000 may further include: adjusting the light diffusion part of the microlens, and making the microlens satisfy: 0≤H / h≤1, wherein H is the step height of the microlens; and h is the sag of the microlens. By constraining the ratio of the step height to the sag of the microlens to be within the range of 0 to 1, it is helpful to achieve a large eye box and high brightness of the projection system including the diffusion element.

[0131] In an exemplary embodiment, the preparation method 1000 may further include: adjusting the light diffusion part of the plurality of microlenses, and making the plurality of microlenses satisfy: H1 / h1>H2 / h2, wherein H1 is the step height of the microlens far from the preset axis among at least two adjacent microlenses, h1 is the sagittal height of the microlens far from the preset axis among at least two adjacent microlenses, H2 is the step height of the microlens close to the preset axis among at least two adjacent microlenses, and h2 is the sagittal height of the microlens close to the preset axis among at least two adjacent microlenses. By controlling the ratio of the step height to the sagittal height of at least two adjacent microlenses to be different, and compared with the microlenses close to the center of the substrate, the microlenses close to the edge of the substrate have a larger ratio of the step height to the sagittal height, the microlenses close to the edge of the substrate can be made to produce a larger deflection of the diffusion of light, and when the diffusion element has a smaller diffusion angle, the diffusion element is ensured to have a larger diffusion surface and higher brightness.

[0132] In an exemplary embodiment, the preparation method 1000 may also include: adjusting the light diffusion part of the plurality of microlenses, and in the first direction and / or the second direction, so that the height difference of the plurality of microlenses gradually increases from the preset axis to the edge of the substrate, and the absolute value of the deflection angle of the plurality of microlenses gradually increases from the preset axis to the edge of the substrate. By controlling the height difference of the plurality of microlenses to gradually change from the preset axis to the edge of the substrate, the absolute value of the deflection angle of the plurality of microlenses can be gradually changed from the preset axis to the edge of the substrate, thereby ensuring that the microlenses close to the edge of the substrate produce a greater deflection for the diffusion of light, and the microlenses close to the center of the substrate produce a smaller deflection or no deflection for the diffusion of light, and in the case where the diffusion element has a smaller diffusion angle, ensure that the diffusion element has a larger diffusion surface and higher brightness. In addition, when the height difference of the plurality of microlenses in the first direction and the second direction changes gradually at the same time, the microlenses close to the edge of the substrate in both directions can produce a greater deflection for the diffusion of light, reduce the diffusion angle of the diffusion element in both directions, and ensure that the diffusion element has a larger diffusion surface and higher brightness in both directions.

[0133] In an exemplary embodiment, the preparation method 1000 may also include: adjusting the light diffusion portion of the plurality of microlenses, and in the first direction and / or the second direction, making the height differences of the plurality of microlenses symmetrically distributed relative to a preset axis; and the absolute values ​​of the deflection angles of the plurality of microlenses symmetrically distributed relative to the preset axis.

[0134] In an exemplary embodiment, the preparation method 1000 may also include: adjusting the light diffusion portion of the plurality of microlenses, and in the first direction and / or the second direction, making the height difference of the plurality of microlenses asymmetrically distributed relative to a preset axis; the absolute values ​​of the deflection angles of the plurality of microlenses asymmetrically distributed relative to the preset axis.

[0135] In an exemplary embodiment, the preparation method 1000 may further include: adjusting a plurality of microlenses, and making the plurality of microlenses satisfy: 0<(|θ1|-|θ2|)×50<FOV, wherein θ1 is the deflection angle of the microlens far from the preset axis among at least two adjacent microlenses, θ2 is the deflection angle of the microlens close to the preset axis among at least two adjacent microlenses, and FOV is the preset diffusion angle of the diffusion element. By making at least two adjacent microlenses have different deflection angles, and compared with the microlens close to the center of the substrate, the microlens close to the edge of the substrate has a larger deflection angle, the microlens close to the edge of the substrate can produce a larger deflection on the diffusion of light, and when the diffusion element has a smaller diffusion angle, the diffusion element is ensured to have a larger diffusion surface and higher brightness. At the same time, the structures and sizes of the two adjacent microlenses are different, thereby suppressing the moiré fringe phenomenon of the diffusion element, improving the imaging quality and uniformity of the diffusion element, and reducing the cost.

[0136] In an exemplary embodiment, the preparation method 1000 may further include: adjusting the light diffusion part of the microlens, and making the microlens satisfy: (0.44-0.004×(|α|-8))×|θ|×(L / 20)≤H×1°×1°≤(0.84-0.004×(|α|-8))×|θ|×(L / 20), wherein H is the step height of the microlens; α is the angle between the main optical axis I of the incident light corresponding to the microlens and the preset axis; θ is the deflection angle of the microlens; and L is the size of the microlens. By constraining the step height of the microlens within the above range, when the microlens has an appropriate deflection angle, the diffraction effect of the microlens can be suppressed, which is conducive to ensuring that the projection system including the diffusion element achieves a large eye box and high brightness, and improves the imaging quality of the projection system, for example, the projection screen of the projection system has no rainbow stripes.

[0137] In an exemplary embodiment, the preparation method 1000 may further include: adjusting the light diffusion portion of the microlens, and making the microlens satisfy: 0≤H / (|θ|×L)×1°≤0.035, wherein H is the height difference of the microlens; θ is the deflection angle of the microlens; and L is the size of the microlens. As an example, 0.0015≤H / (|θ|×L)×1°≤0.035. By controlling the above conditional formula, when the microlens has an appropriate deflection angle, the diffraction effect of the microlens can be suppressed, which is beneficial to ensure that the projection system including the diffusion element achieves a large eye box and high brightness, and improves the imaging quality of the projection system, for example, the projection screen of the projection system has no rainbow stripes.

[0138] In an exemplary embodiment, the preparation method 1000 may further include: adjusting the light diffusion parts of the plurality of microlenses in the first direction and / or the second direction, and making the preset diffusion surfaces of the microlenses located at the two opposite sides of the substrate substantially overlap, for example, the overlap area of ​​the preset diffusion surfaces of the microlenses located at the two opposite sides of the substrate is about 95% or more of the area of ​​the preset diffusion surfaces. By controlling the diffusion of the microlenses at the two opposite sides of the substrate and deflecting them toward the center of the substrate at the same time, it is possible to reduce the waste of light, and when the diffusion element has a smaller diffusion angle, it is ensured that the diffusion element has a larger diffusion surface and higher brightness.

[0139] The third aspect of the present application provides a projection system. The projection system may be, for example, a head-up display system. The projection system may include an image generation module, a diffusion element as described in the first aspect of the present application, and a projection module. The image generation module may be used to emit image light carrying image information. The diffusion element may be used to diffuse the image light to form diffused light. The projection module may be used to project diffused light, for example, to project the diffused light to an eye box area.

[0140] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the above features are formed by replacing each other with the technical features with similar functions disclosed in this application (but not limited to).

Claims

1. A diffusion element, characterized in that: include: substrate; as well as A plurality of micro lenses are disposed on one side surface of the substrate; Wherein, the distance from the position farthest from the substrate to the preset axis of at least one of the microlenses is smaller than the distance from the center of the surface of the microlens close to the substrate to the preset axis, and the preset axis is parallel to the central axis of the substrate; The microlens includes a light diffusion portion, and the light diffusion portion includes a first end away from the preset axis and a second end close to the preset axis; the step height of at least one of the microlenses is greater than 0 μm, and the step height of the microlens is the distance from the second end of the light diffusion portion of the microlens to the first end of another light diffusion portion adjacent to the second end of the light diffusion portion; The microlens satisfies: 0≤H / (|θ|×L)×1°≤0.035, H is the step height of the microlens; θ is the deflection angle of the microlens, which is the angle between the main optical axis of the outgoing light corresponding to the microlens and the main optical axis of the incident light; and L is the size of the microlens.

2. The diffusion element according to claim 1, wherein The principal optical axis of the outgoing light emitted from at least one of the microlenses is inclined toward a direction close to the preset axis relative to the principal optical axis of the incident light.

3. The diffusion element according to claim 1, wherein The plurality of microlenses satisfy: |θ1|>|θ2|, Wherein, θ1 is the deflection angle of the microlens far from the preset axis among at least two adjacent microlenses, and θ2 is the deflection angle of the microlens close to the preset axis among at least two adjacent microlenses.

4. The diffusion element according to claim 1, wherein The difference in absolute value of curvature between the first end and the second end of the light diffusion portion of the plurality of microlenses gradually increases from the preset axis toward the edge of the substrate.

5. The diffusion element according to claim 1, wherein The diffusion element further comprises: The connecting portion extends from the second end of the light diffusion portion of one of the microlenses toward the substrate, and a side of the connecting portion close to the substrate is connected to a first end of the light diffusion portion of another microlens adjacent to the microlens.

6. The diffusion element according to claim 1, wherein: The step height of at least one of the microlenses close to the preset axis is equal to 0 μm.

7. The diffusion element according to claim 1, wherein: The plurality of microlenses are arranged on one side surface of the substrate along a first direction and / or a second direction, wherein the first direction and the second direction intersect and are both parallel to the surface of the substrate on which the microlenses are arranged.

8. The diffusion element according to claim 7, wherein: In the first direction and / or the second direction, a center of a preset diffusion surface of at least one of the microlenses is closer to the preset axis than a center of a surface of the microlens close to the substrate.

9. The diffusion element according to claim 7, wherein: In the first direction and / or the second direction, at least two of the microlenses have different step heights, and at least two of the microlenses have different absolute values ​​of deflection angles.

10. The diffusion element according to claim 9, wherein: In the first direction and / or the second direction, the height difference of the plurality of microlenses gradually increases from the preset axis to the edge of the substrate, and the absolute value of the deflection angle of the plurality of microlenses gradually increases from the preset axis to the edge of the substrate.

11. The diffusion element according to claim 9, wherein: In the first direction and / or the second direction, the height differences of the plurality of microlenses are symmetrically or asymmetrically distributed relative to the preset axis; the absolute values ​​of the deflection angles of the plurality of microlenses are symmetrically or asymmetrically distributed relative to the preset axis.

12. The diffusion element according to claim 3, wherein: The plurality of microlenses satisfy: 0<(|θ1|-|θ2|)×50<FOV, Wherein, FOV is a preset diffusion angle of the diffusion element.

13. The diffusion element according to any one of claims 1 to 11, wherein The plurality of microlenses satisfy: H1>H2, Wherein, H1 is the step height of at least two adjacent microlenses that are far from the preset axis, and H2 is the step height of at least two adjacent microlenses that are close to the preset axis.

14. The diffusion element according to any one of claims 1 to 11, wherein The microlens satisfies: 0≤H / h≤1, Among them, H is the step height of the microlens; h is the sagittal height of the microlens, and the sagittal height of the microlens is the distance from the position of the light diffusion part of the microlens farthest from the substrate to the first end of another light diffusion part adjacent to the second end of the light diffusion part.

15. The diffusion element according to claim 14, wherein The plurality of microlenses satisfy: H1 / h1>H2 / h2, Among them, H1 is the step height of at least two adjacent microlenses away from the preset axis, h1 is the sagittal height of at least two adjacent microlenses away from the preset axis, H2 is the step height of at least two adjacent microlenses close to the preset axis, and h2 is the sagittal height of at least two adjacent microlenses close to the preset axis.

16. The diffusion element according to any one of claims 1 to 11, wherein The microlens satisfies: (0.44-0.004×(|α|-8))×|θ|×(L / 20)≤H×1°×1°≤(0.84-0.004×(|α|-8))×|θ|×(L / 20), Wherein, H is the height difference of the microlens; α is the angle between the main optical axis of the incident light corresponding to the microlens and the preset axis; θ is the deflection angle of the microlens; and L is the size of the microlens.

17. The diffusion element according to any one of claims 1 to 11, wherein The preset diffusion surfaces of the microlenses located at two opposite side edges of the substrate overlap.

18. A method for preparing a diffusion element, characterized in that: include: forming a plurality of micro lenses on one side surface of the substrate; as well as Adjusting the plurality of microlenses so that a distance from a position of at least one of the microlenses that is farthest from the substrate to a preset axis is smaller than a distance from a center of a surface of the microlens that is close to the substrate to the preset axis, and the preset axis is parallel to a central axis of the substrate; The microlens includes a light diffusion portion, and the light diffusion portion includes a first end away from the preset axis and a second end close to the preset axis; the step height of at least one of the microlenses is greater than 0 μm, and the step height of the microlens is the distance from the second end of the light diffusion portion of the microlens to the first end of another light diffusion portion adjacent to the second end of the light diffusion portion; The microlens satisfies: 0≤H / (|θ|×L)×1°≤0.035, H is the step height of the microlens; θ is the deflection angle of the microlens, which is the angle between the main optical axis of the outgoing light corresponding to the microlens and the main optical axis of the incident light; and L is the size of the microlens.

19. A projection system, characterized in that: include: An image generation module, used for emitting image light carrying image information; The diffusion element according to any one of claims 1 to 17, configured to diffuse the image light to form diffused light; as well as The projection module is used for projecting the diffused light.

Images