Diffusion element and preparation method therefor, and projection system

Abstract

The present application discloses a diffusion element and a preparation method therefor, 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. For at least one microlens, the distance from the position of the microlens farthest away from the substrate to a preset axis is smaller than the distance from the center of the surface of a microlens close to the substrate to the preset axis, and the preset axis is parallel to the central axis of the substrate.

Description

Diffusion element, preparation method thereof, and projection system TECHNICAL FIELD

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

[0002] The diffusion element can modulate the incident light to form a relatively uniform light field as much as possible, and thus the diffusion element is widely applied in the fields of head-up display systems, laser radars, projection systems, etc. In a head-up display system, the range of an eyebox is related to the diffusion angle of the diffusion element. For example, the larger the range of the eyebox, the larger the diffusion angle of the diffusion element required. However, when the diffusion angle of the diffusion element is large, the brightness of the eyebox will be significantly reduced.

[0003] In order to realize a large eyebox and high brightness, the two side surfaces of the diffusion element can be provided with microstructures, and the sizes of the microstructures on the two sides of the diffusion element are relatively close, which can cause the diffusion element to easily generate Moire fringe phenomenon, and the sizes of the microstructures on the two sides of the diffusion element need to be aligned, and the preparation process of the diffusion element is relatively complex and the cost is relatively high. SUMMARY

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

[0005] A first aspect of the present application provides a diffusion element, comprising a substrate and a plurality of microlenses; the plurality of microlenses are arranged on one side surface of the substrate; wherein the distance from the farthest position of at least one microlens to a preset axis is less 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.

[0006] According to an example embodiment of the present application, the principal axis of the emergent light from the at least one microlens is inclined to the direction close to the preset axis relative to the principal axis of the incident light.

[0007] According to an example embodiment of the present application, the plurality of microlenses satisfy |θ1| > |θ2|, wherein θ1 is the deflection angle of the microlens far from the preset axis in at least two adjacent microlenses, and θ2 is the deflection angle of the microlens close to the preset axis in at least two adjacent microlenses, and the deflection angle of the microlens is the included angle between the principal axis of the corresponding emergent light of the microlens and the principal axis of the incident light.

[0008] According to an example embodiment of the present application, the microlens comprises a light diffusion portion, the light diffusion portion comprises a first end away from the preset axis and a second end close to the preset axis; wherein the height difference of at least one microlens is greater than 0 μm, the height difference 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 example embodiment of the present application, the difference between the absolute values of the curvatures of the first end and the second end of the light diffusion portion of the plurality of microlenses gradually increases from the preset axis to the edge of the substrate.

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

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

[0012] According to an example embodiment of the present application, 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.

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

[0014] According to an example embodiment of the present application, in the first direction and / or the second direction, the height difference of at least two microlenses is different, and the absolute value of the refraction angle of the at least two microlenses is different, wherein the refraction angle of the microlens is the included angle between the principal axis of the outgoing light corresponding to the microlens and the principal axis of the incident light.

[0015] According to an example 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 refraction angle of the plurality of microlenses gradually increases from the preset axis to the edge of the substrate.

[0016] According to an example embodiment of the present application, in the first direction and / or the second direction, the height difference of the plurality of microlenses is symmetrically distributed or asymmetrically distributed with respect to the preset axis, and the absolute value of the refraction angle of the plurality of microlenses is symmetrically distributed or asymmetrically distributed with respect to the preset axis.

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

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

[0019] According to an example embodiment of the present application, the microlens satisfies: 0 ≤ H / h ≤ 1, wherein H is a height difference of the microlens, and h is a sag height of the microlens, the sag height of the microlens being a distance from a position farthest from a base in a light diffusion portion of the microlens to a first end of another light diffusion portion adjacent to a second end of the light diffusion portion.

[0020] According to an example embodiment of the present application, the plurality of microlenses satisfy: H1 / h1 > H2 / h2, wherein H1 is a height difference of a microlens far from the preset axis among at least two adjacent microlenses, h1 is a sag height of the microlens far from the preset axis among the at least two adjacent microlenses, H2 is a height difference of a microlens close to the preset axis among the at least two adjacent microlenses, and h2 is a sag height of the microlens close to the preset axis among the at least two adjacent microlenses.

[0021] According to an example embodiment of the present application, the microlens satisfies: (0.44 - 0.004 x (|α| - 8)) x |θ| x (L / 20) ≤ H x 1° x 1° ≤ (0.84 - 0.004 x (|α| - 8)) x |θ| x (L / 20), wherein H is a height difference of the microlens, α is an included angle between a principal axis of an incident light corresponding to the microlens and a preset axis, θ is a refraction angle of the microlens, the refraction angle of the microlens being an included angle between a principal axis of an emergent light corresponding to the microlens and a principal axis of the incident light, and L is a size of the microlens.

[0022] According to an example embodiment of the present application, the microlens satisfies: 0 ≤ H / (|θ| x L) x 1° ≤ 0.035, wherein H is a height difference of the microlens, θ is a refraction angle of the microlens, the refraction angle of the microlens being an included angle between a principal axis of an emergent light corresponding to the microlens and a principal axis of an incident light, and L is a size of the microlens.

[0023] According to an example embodiment of the present application, preset diffusion surfaces of the microlenses located at opposite side edges of the base coincide.

[0024] The second aspect of the present application provides a preparation method of a diffusion element, comprising: forming a plurality of microlenses on one side surface of a substrate; and adjusting the plurality of microlenses so that the distance from the position farthest from the substrate of at least one microlens to a preset axis is less than the distance from the center of the surface close to the substrate of the microlens 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, comprising 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 for emitting image light carrying image information; the diffusion element is used for diffusing the image light to form diffused light; and the projection module is used for projecting the diffused light.

[0026] The diffusion element provided by the present application can make the diffusion of light by at least one microlens deviate to the center of the substrate, ensure that the diffusion element has a larger diffusion surface and higher brightness in the case that the diffusion element has a smaller diffusion angle, and is beneficial to realize a large eyebox and high brightness. In addition, the preparation process difficulty and cost of the diffusion element can be reduced. BRIEF DESCRIPTION OF DRAWINGS

[0027] Other features, objects and advantages of the embodiments of the present application will become more apparent from the following detailed description of non-limiting embodiments with reference to the attached drawings. Among which:

[0028] FIG. 1 shows a diffusion schematic diagram of a diffusion element in the prior art;

[0029] FIG. 2 shows a structural schematic diagram of a diffusion element in the prior art;

[0030] FIG. 3 shows a structural schematic diagram of a microlens in the prior art;

[0031] FIG. 4 shows a structural schematic diagram of another diffusion element in the prior art;

[0032] FIG. 5 shows a structural schematic diagram of a diffusion element according to an exemplary embodiment of the present application;

[0033] FIG. 6 shows a diffusion schematic diagram of a diffusion element according to an exemplary embodiment of the present application;

[0034] FIG. 7 shows a structural schematic diagram of a microlens according to an exemplary embodiment of the present application;

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

[0036] FIG. 9 shows a diffusion schematic of a diffusion element according to an exemplary embodiment of the present application;

[0037] FIG. 10 shows an a-a sectional schematic view of FIG. 8;

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

[0039] FIG. 12 shows an a-a sectional schematic view of FIG. 11;

[0040] FIG. 13 shows a b-b sectional schematic view of FIG. 11; and

[0041] FIG. 14 shows a flow schematic of a method of manufacturing a diffusion element according to an exemplary embodiment of the present application. DETAILED DESCRIPTION

[0042] For a better understanding of the present application, various aspects of the present application will be described in greater detail below with reference to the accompanying drawings. It is to be understood that the detailed description is merely exemplary of the application and is not intended to limit the scope of the application in any way. Throughout the specification, like reference numerals refer to like elements in which: the expression "and / or" includes any and all combinations of one or more of the associated listed items.

[0043] It is to be noted that the terms first, second, etc. can be used herein to distinguish one element from another and do not necessarily have to follow an ordinal numerical usage, unless specified. Thus, a first direction discussed below can be termed a second direction without departing from the teachings of the present application.

[0044] In the drawings, the thicknesses of the components, sizes, and shapes can be exaggerated slightly for the sake of convenience and ease of explanation. The drawings are merely schematic and are not intended to be drawn to scale.

[0045] It is also to be understood that the terms "comprise", "comprising", "have", "has", "including", or "including" as used herein, specify the presence of stated features, elements, and / or components, but do not preclude the presence or addition of one or more other features, elements, components, and / or groups thereof. In addition, "exemplary" is intended to mean an example or illustration.

[0046] Unless otherwise defined, all terms (including technical and scientific terms) used in the present application have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined in the present application.

[0047] It should be noted that the embodiments and features of the embodiments in the present application can be combined with each other in the case of no conflict. 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 in the following, the first direction can be referred to as the X direction, the second direction can be referred to as the Y direction, and the third direction can be referred to as the Z direction. The X direction, the Y direction, and the Z direction in each of the accompanying drawings show the spatial relationship of each component 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 intersecting (for example, perpendicular) with each other in a plane intersecting (for example, perpendicular) the height direction. In addition, the X direction, the Y direction, and the Z direction in each of the accompanying drawings not only include the direction indicated by the arrow, but also include the direction away from the arrow, in other words, the arrow in the X direction, the Y direction, and the Z direction does not have a limiting meaning. The same concept will be used throughout the present application to describe the spatial relationship of each component 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 an eyebox region. The eyebox region can be a region where the observer's eyes are located, and the image output by the head-up display system can be observed.

[0050] The range of the eyebox region 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 eyebox region. As shown in FIG. 1, the eyebox region 250 can be the overlapping region of the diffusion angles of the opposite two side edges of the diffusion element 200, the larger the range of the eyebox region 250, the larger the diffusion angle of the diffusion element 200 required, and the lower the brightness of the eyebox.

[0051] Specifically, FIG. 2 shows a structural schematic diagram of the diffusion element 200. FIG. 3 shows a structural schematic diagram of the microlens 220. The incident light rays enter into the substrate 210 and exit after being diffused by the plurality of microlenses 220 on the substrate. The absolute values of the curvatures of the two side endpoints of the light diffusion portion 221 of each microlens 220 are the same, for example, the absolute values of the curvatures of the first end A and the second end B of the light diffusion portion 221 are the same. Due to the absolute values of the curvatures of the first end A and the second end B of the light diffusion portion 221 being the same, the refractions of the light rays with the same incident angle occurring at the first end A and the second end B of the light diffusion portion 221 are the same, that is, the center of the preset diffusion plane 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 rays 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 planes 260 of the opposite two side edges of the diffusion element 200 is the eyebox area 250. When the range of the eyebox area 250 is larger, the required diffusion angle of the diffusion element 200 is larger, and the brightness of the eyebox is lower.

[0052] In order to realize a large eyebox and high brightness of the head-up display system, the two side surfaces of the substrate 210 in the diffusion element 200 can be provided with microstructures. As shown in FIG. 4, one side surface of the substrate 210 is a Fresnel structure 270, the other side surface is a microlens 220, and the microstructure sizes of the two side surfaces of the substrate 210 are relatively close, for example, both are tens of microns, which will cause the diffusion element 200 to easily produce Moire fringe phenomenon, the projection picture of the head-up display system will appear ghosting, and the microstructure sizes of the two side surfaces of the substrate 210 need to be aligned, the preparation process of the diffusion element 200 is relatively complex, and the cost is relatively high.

[0053] In order to at least partially solve one or more of the above problems and other potential problems, the first aspect of the present application proposes a diffusion element, specifically, proposes a diffusion element in which a plurality of microlenses are arranged on one side surface of a substrate, and the diffusion of light by at least one microlens is deflected towards the center of the substrate, so as to ensure that the diffusion element has a larger diffusion plane and higher brightness while having a smaller diffusion angle.

[0054] FIG. 5 shows a structural schematic diagram of the diffusion element 200 according to an example embodiment of the present application. FIG. 6 shows a diffusion schematic diagram of the diffusion element 200 according to an example embodiment of the present application. FIG. 7 shows a structural schematic diagram of the microlens 220 according to an example 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, which are not specifically limited in the present application.

[0055] Referring to FIGS. 5, 6 and 7, the diffusion element 200 can include a substrate 210 and a plurality of microlenses 220. The substrate 210 can include oppositely arranged first and second surfaces. The first surface can be, for example, a light-incident surface. The second surface can be, for example, a light-emergent surface. The plurality of microlenses 220 can be arranged on one side surface of the substrate 210, for example, on the second surface of the substrate 210.

[0056] A distance from a position of at least one microlens 220 farthest from the substrate 210 to a preset axis 240 can be less than a distance from a center of a surface of the microlens 220 close to the substrate 210 to the preset axis 240, where the preset axis 240 can be parallel to a central axis of the substrate 210. In other words, the preset axis 240 can be the central axis of the substrate 210, or the preset axis 240 can be spaced apart from the central axis of the substrate 210 by a certain distance.

[0057] By arranging the plurality of microlenses 220 on one side surface of the substrate 210, and by making a distance from a position of at least one microlens 220 farthest from the substrate 210 (e.g., a vertex C) to the preset axis 240 less than a distance from a center of a surface of the microlens 220 close to the substrate 210 to the preset axis 240, the microlens 220 can be caused to deflect the diffusion of light toward the center of the substrate, and in the case where the diffusion element 200 has a small diffusion angle, the diffusion element 200 can be ensured to have a large diffusion area and high brightness, thereby facilitating the realization of a large eye box and high brightness of a projection system including the diffusion element. In addition, the preparation process difficulty and cost of the diffusion element 200 can be reduced.

[0058] In an exemplary embodiment, the substrate 210 can have a thin plate structure, and can be made of a transparent material.

[0059] In an exemplary embodiment, the incident light can enter the substrate 210 through the first surface of the substrate, and be diffused through the plurality of microlenses 220 on the second surface of the substrate and then emerge. For at least one microlens 220, a principal axis II of the emergent light from the microlens 220 can be deflected relative to a principal axis I of the incident light, for example, the principal axis II of the emergent light from the microlens 220 can be inclined relative to the principal axis I of the incident light toward the preset axis 240, in other words, there can be an included angle between the principal axis II of the emergent light corresponding to the microlens 220 and the principal axis I of the incident light, and the included angle between the principal axis II of the emergent light corresponding to the microlens 220 and the principal axis I of the incident light can be referred to as a deflection angle θ of the microlens 220 (e.g., FIG. 9).

[0060] By tilting the principal axis II of the emergent light rays exiting the at least one microlens 220 relative to the principal axis I of the incident light rays towards the direction close to the preset axis 240, the diffusion of light by the microlens 220 can be deflected towards the center of the substrate. In the case that the diffusion element 200 has a small diffusion angle, the diffusion element 200 can have a large diffusion area and high brightness, thereby facilitating the realization of a large eye box and high brightness of a projection system comprising the diffusion element. In addition, the preparation process difficulty and cost of the diffusion element 200 can be reduced.

[0061] In an exemplary embodiment, for at least some of the microlenses 220, the principal axis II of the emergent light rays exiting the microlens 220 can not be deflected relative to the principal axis I of the incident light rays, in other words, the deflection angle θ of the microlens 220 can be 0°. For example, the deflection angle θ of the microlenses 220 arranged in the central region of the substrate can be 0°.

[0062] In an exemplary embodiment, the plurality of microlenses 220 can satisfy: |θ1| > |θ2|, where 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 herein is the same, and the deflection angle of the microlens will not be described below.

[0063] By diffusing light by the microlenses 220 close to the edge of the substrate towards the center of the substrate, in the case that the diffusion element 200 has a small diffusion angle, the diffusion element 200 can have a large diffusion area and high brightness, thereby facilitating the realization of a large eye box and high brightness of a projection system comprising the diffusion element. In addition, at least two adjacent microlenses 220 can have different structure sizes, which is conducive to weakening the Moire fringe phenomenon of the diffusion element 200, improving the imaging quality and uniformity of the diffusion element 200, and reducing the preparation process difficulty and cost of the diffusion element 200.

[0064] In an example embodiment, referring to FIGS. 10, 12, and 13, any two adjacent microlenses 220 in the plurality of microlenses can include a first microlens 2201 and a second microlens 2202. The first microlens 2201 can be distal to the preset axis 240, and the second microlens 2202 can be proximal to the preset axis 240. The deflection angle θ1 of the first microlens 2201 and the deflection angle θ2 of the second microlens 2202 can 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 can be disposed in the central region of the substrate, and the deflection angles of the first microlens 2201 and the second microlens 2202 can be 0°.

[0065] In an example embodiment, referring to FIGS. 7, 10, 12, and 13, the microlens 220 can include a light diffusion portion 221. The light diffusion portion 221 can be a surface of the microlens 220 distal to the substrate, which can be, for example, a curved surface. The light diffusion portion 221 can include a first end A and a second end B, the first end A can be distal to the preset axis 240, and the second end B can be proximal to the preset axis 240. The absolute value of the curvature of the first end A of the light diffusion portion 221 can 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 can be positively correlated with the difference between the absolute values of the curvatures of the first end A and the second end B of the light diffusion portion 221. In other words, the greater the difference between the absolute values of the curvatures of the first end A and the second end B of the light diffusion portion 221, the greater the deflection angle of the microlens 220; the smaller the difference between the absolute values of the curvatures of the first end A and the second end B of the light diffusion portion 221, the smaller the deflection angle of the microlens 220. When the difference between the absolute values of the curvatures of the first end A and the second end B of the light diffusion portion 221 is 0, the deflection angle of the microlens 220 can be 0°.

[0067] In the example embodiment, the difference between the absolute values of the curvatures of the first end A and the second end B of the light diffusion portion 221 of the plurality of microlenses gradually increases from the preset axis 240 to the edge of the substrate 210. By making the difference between the absolute values of the curvatures of the first end A and the second end B of the light diffusion portion 221 of the plurality of microlenses gradually increase from the preset axis 240 to the edge of the substrate 210, it can be ensured that the microlenses 220 close to the edge of the substrate have a greater deflection for the diffusion of light, the microlenses 220 close to the center of the substrate have a smaller deflection or no deflection for the diffusion of light, and in the case that the diffusion element 200 has a smaller diffusion angle, the diffusion element 200 has a larger diffusion area and higher brightness, thereby facilitating the realization of a large eye box and high brightness of a projection system comprising the diffusion element. In addition, it can also make different microlenses 220 have different structural sizes, which is conducive to weakening the Moiré 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 the example embodiment, the step height of at least one microlens 220 can be greater than 0 μm. The step height H of the microlens 220 can be the distance (for example, the distance in the third direction) 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. It should be understood that the concept of the step height of the microlens herein is the same, and the step height of the microlens will not be described below.

[0069] By controlling the step height of at least one microlens 220 to be greater than 0 μm, the diffusion of light by the microlens 220 can be deflected towards the center of the substrate 210, and in the case that the diffusion element 200 has a smaller diffusion angle, the diffusion element 200 has a larger diffusion area and higher brightness, thereby facilitating the realization of a large eye box and high brightness of a projection system comprising the diffusion element.

[0070] In the example embodiment, referring to FIGS. 10, 12 and 13, the step height of at least one microlens 220 close to the preset axis 240 can be equal to 0 μm. In other words, the second end B of the light diffusion portion 221 of at least one microlens close to the preset axis 240 can 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 can 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 can be equal to 0 μm.

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

[0072] In an exemplary embodiment, the plurality of microlenses 220 can be arranged on one side surface of the substrate 210 along a first direction and / or a second direction, wherein the first direction and the second direction are intersected and both are parallel to the surface of the substrate 210 on which the microlenses 220 are arranged. The plurality of microlenses 220 can be arranged on the second surface of the substrate 210 along the first direction; or the plurality of microlenses 220 can be arranged on the second surface of the substrate 210 along the second direction; or the plurality of microlenses 220 can be arranged on the second surface of the substrate 210 in an array along the first direction and the second direction. For example, the plurality of microlenses 220 can be arranged on the second surface of the substrate 210 in, for example, m rows by n columns, the first direction can be, for example, the row direction, and the second direction can be, for example, the column direction.

[0073] In an exemplary embodiment, in the first direction and / or the second direction, the principal axis II of the emergent light ray from at least one microlens 220 can be deflected relative to the principal axis I of the incident light ray, and accordingly, the center of the preset diffusion plane 260 of the microlens 220 can 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 plane 260 of at least one microlens 220 (for example, the 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 can be greater than 0°.

[0074] Referring to FIG. 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, and thus the refractions of the light rays with the same incident angle at the first end A and the second end B of the light diffusion portion 221 are different. The center of the preset diffusion surface 260 of the microlens 220 (for example, the midpoint of the line segment on which the end point D and the end point E are located) is deflected relative to the center of the surface of the microlens 220 close to the substrate. The overlapping area of the preset diffusion surfaces 260 of the microlenses located on the opposite edges of the substrate can be the eyebox area 250 (as shown in FIG. 6). By controlling the center of the preset diffusion surface 260 of the microlens 220 close to the edge of the substrate to be deflected relative to the center of the surface of the microlens 220 close to the substrate, in the case that the diffusion angle of the diffusion element 200 is small, the diffusion element 200 can have a large diffusion surface and high brightness, thereby facilitating the realization of a large eyebox and high brightness of a projection system including the diffusion element.

[0075] In an example embodiment, referring to FIGS. 10, 12 and 13, the absolute values of the deflection angles θ of the at least two microlenses 220 in the first direction and / or the second direction are different. For example, the absolute values of the deflection angles θ of the at least two adjacent microlenses 220 are different. By controlling the at least two adjacent microlenses 220 to have different absolute values of the deflection angles, the at least two adjacent microlenses 220 can have different structural sizes, which is conducive to weakening the Moiré fringe phenomenon of the diffusion element 200 and improving the imaging quality and uniformity of the diffusion element 200.

[0076] In an example embodiment, referring to FIGS. 10, 12 and 13, the absolute values of the deflection angles θ of the at least two microlenses 220 in the first direction and / or the second direction are different. For example, the absolute values of the deflection angles θ of the at least two adjacent microlenses 220 are different. By controlling the at least two adjacent microlenses 220 to have different absolute values of the deflection angles, the at least two adjacent microlenses 220 can have different structural sizes, which is conducive to weakening the Moiré fringe phenomenon of the diffusion element 200 and improving the imaging quality and uniformity of the diffusion element 200.

[0077] In an example embodiment, referring to FIGS. 10, 12 and 13, the plurality of microlenses 220 can satisfy H1>H2, where H1 is the height difference of the microlens away from the preset axis 240 in the at least two adjacent microlenses 220, and H2 is the height difference of the microlens close to the preset axis 240 in the at least two adjacent microlenses 220. For example, the height difference H1 of the first microlens 2201 can be greater than the height difference H2 of the second microlens 2202.

[0078] The height difference of the microlens 220 can correspond to the absolute value of the deflection angle of the microlens 220 one by one. That is, the height difference of the microlens 220 is different, and the absolute value of the deflection angle of the microlens 220 is different. The absolute value of the deflection angle of the microlens 220 can be positively correlated with the height difference of the microlens 220. By making at least two adjacent microlenses 220 have different height differences, and the microlenses 220 near the edge of the base have larger height differences than the microlenses 220 near the center of the base, the microlenses 220 near the edge of the base can produce greater deflection to the diffusion of light, and in the case that the diffusion element 200 has a smaller diffusion angle, the diffusion element 200 has a larger diffusion area and higher brightness, thereby facilitating the realization of a large eye box and high brightness of the projection system including the diffusion element.

[0079] In an example embodiment, with reference to FIGS. 10, 12 and 13, the microlens 220 can satisfy: 0≤H / h≤1, where H is the height difference of the microlens 220, and h is the sag of the microlens 220, which is the distance (for example, the distance in the third direction) from the position (for example, the vertex C) farthest from the base 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. By constraining the ratio of the height difference of the microlens 220 to the sag within the range of 0 to 1, it is beneficial to realize 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 herein is the same, and the sag of the microlens will not be described below.

[0080] In an example embodiment, with reference to FIGS. 10, 12 and 13, the plurality of microlenses 220 can satisfy: H1 / h1>H2 / h2, where H1 is the height difference of the microlens farthest from the preset axis 240 in at least two adjacent microlenses 220, h1 is the sag of the microlens farthest from the preset axis 240 in at least two adjacent microlenses 220, H2 is the height difference of the microlens closest to the preset axis 240 in at least two adjacent microlenses 220, and h2 is the sag of the microlens closest to the preset axis 240 in at least two adjacent microlenses 220.

[0081] By controlling the ratio of the height difference to the sag of at least two adjacent microlenses 220 to be different, and the microlenses 220 near the edge of the base have a larger ratio of the height difference to the sag than the microlenses 220 near the center of the base, the microlenses 220 near the edge of the base can produce greater deflection to the diffusion of light, and in the case that the diffusion element 200 has a smaller diffusion angle, the diffusion element 200 has a larger diffusion area and higher brightness, thereby facilitating the realization of a large eye box and high brightness of the projection system including the diffusion element.

[0082] In the example embodiment, referring to FIGS. 10, 12 and 13, in the first direction and / or the second direction, the height difference of the plurality of 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 plurality of microlenses 220 can gradually increase from the preset axis 240 to the edge of the substrate 210.

[0083] By controlling the height difference 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 gradually change from the preset axis 240 to the edge of the substrate, so that the microlenses 220 close to the edge of the substrate produce greater deflection on the diffusion of light, and the microlenses 220 close to the center of the substrate produce smaller deflection or no deflection on the diffusion of light. In the case that the diffusion element 200 has a smaller diffusion angle, the diffusion element 200 has a larger diffusion area and higher brightness, which is beneficial to realize large eye box and high brightness of the projection system including the diffusion element. In addition, when the height difference of the plurality of microlenses 220 in the first direction and the second direction gradually changes at the same time, the microlenses 220 close to the edge of the substrate in both directions produce greater deflection on the diffusion of light, the diffusion angle of the diffusion element 200 in both directions is reduced, and the diffusion element 200 has a larger diffusion area and higher brightness in both directions.

[0084] In the example embodiment, referring to FIG. 10, in the first direction and / or the second direction, the height difference of the plurality of microlenses 220 can be symmetrically distributed relative to the preset axis 240, and the absolute value of the deflection angle of the plurality of microlenses 220 can be symmetrically distributed relative to the preset axis 240.

[0085] In the example embodiment, referring to FIGS. 12 and 13, in the first direction and / or the second direction, the height difference of the plurality of microlenses 220 can be asymmetrically distributed relative to the preset axis 240, and the absolute value of the deflection angle of the plurality of microlenses 220 can be asymmetrically distributed relative to the preset axis 240.

[0086] In the example embodiment, the plurality of microlenses 220 can satisfy: 0 < (|θ1|-|θ2|) x 50 < FOV, wherein θ1 is the deflection angle of the microlens away from the preset axis 240 in at least two adjacent microlenses 220, θ2 is the deflection angle of the microlens close to the preset axis 240 in at least two adjacent microlenses 220, 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 the microlenses 220 near the edge of the substrate have larger deflection angles than the microlenses 220 near the center of the substrate, the microlenses 220 near the edge of the substrate can produce greater deflection on the diffusion of light, ensuring that the diffusion element 200 has a larger diffusion area and higher brightness in the case of a smaller diffusion angle of the diffusion element 200, thereby facilitating the realization of a large eye box and high brightness of a projection system including the diffusion element. At the same time, the structures and sizes of the two adjacent microlenses 220 are different, thereby inhibiting the Moiré phenomenon of the diffusion element 200, improving the imaging quality and uniformity of the diffusion element 200, and reducing the cost.

[0088] In an example embodiment, the microlenses 220 can satisfy: (0.44-0.004×(|a|-8))×|θ|×(L / 20)≤H×1°×1°≤(0.84-0.004×(|a|-8))×|θ|×(L / 20), where H is the height difference of the microlenses 220; a is the included angle between the principal axis I of the incident light corresponding to the microlenses 220 and the preset axis 240; θ is the deflection angle of the microlenses 220; and L is the size of the microlenses 220. The size of the microlenses 220 can be the size of the microlenses 220 in the first direction or the second direction. By constraining the height difference of the microlenses 220 within the above range, the diffraction effect of the microlenses 220 can be inhibited when the microlenses 220 have appropriate deflection angles, which is conducive to ensuring that the projection system including the diffusion element realizes a large eye box and high brightness, and improving the imaging quality of the projection system, such as the projection system having no rainbow stripes on the projected image.

[0089] In an example embodiment, the microlenses 220 can satisfy: 0≤H / (|θ|×L)×1°≤0.035, where H is the height difference of the microlenses 220; θ is the deflection angle of the microlenses 220; and L is the size of the microlenses 220. The size of the microlenses 220 can be the size of the microlenses 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 microlenses 220 is a constant value, the absolute value of the deflection angle of the microlenses 220 can be positively correlated with the height difference of the microlenses 220. When the size of the microlenses 220 is randomly distributed, the absolute value of the deflection angle of the microlenses 220 can be positively correlated with the ratio of the height difference to the size of the microlenses 220. By controlling the above condition, the diffraction effect of the microlenses 220 can be inhibited when the microlenses 220 have appropriate deflection angles, which is conducive to ensuring that the projection system including the diffusion element realizes a large eye box and high brightness, and improving the imaging quality of the projection system, such as the projection system having no rainbow stripes on the projected image.

[0090] In the example embodiment, referring to FIG. 6, the preset diffusion faces 260 of the microlenses 220 located at opposite side edges of the substrate substantially coincide in the first direction and / or the second direction, for example, the coinciding area of the preset diffusion faces 260 of the microlenses 220 located at opposite side edges of the substrate is greater than or equal to 95% of the area of the preset diffusion face 260. By controlling the diffusion of the microlenses at the opposite side edges of the substrate to be deflected towards the center of the substrate at the same time, the waste of light can be reduced, and in the case that the diffusion element 200 has a small diffusion angle, the diffusion element 200 is ensured to have a large diffusion face and high brightness, thereby facilitating the realization of a large eye box and high brightness of a projection system comprising the diffusion element.

[0091] The specific embodiments of the diffusion element 200 applicable to the above-mentioned embodiments are further described below.

[0092] Embodiment 1

[0093] FIG. 8 shows a top view of the diffusion element 200 according to Embodiment 1 of the present application. FIG. 9 shows a diffusion schematic diagram of the diffusion element 200 according to Embodiment 1 of the present application. FIG. 10 shows a schematic diagram of the a-a cross section of FIG. 8.

[0094] Referring to FIGS. 8-10, the diffusion element 200 can include a substrate 210 and a plurality of microlenses 220. The plurality of microlenses 220 can be arranged in an array along a first direction and a second direction on a second surface of the substrate 210. The diffusion element 200 has a size of 100 mm in the first direction and a size of 40 mm in the second direction. The diffusion element 200 has a preset diffusion angle FOV1 of 20° in the first direction and a preset diffusion angle FOV2 of 10° in the second direction. The size of the microlenses 220 in the first direction and the second direction is 20 μm.

[0095] In the first direction, the step heights of the plurality of microlenses 220 can be symmetrically distributed relative to a preset axis 240, and the absolute values of the deflection angles of the plurality of microlenses 220 can be symmetrically distributed relative to the preset axis 240. In addition, in the first direction, the step heights of the plurality of microlenses 220 can gradually increase from the preset axis 240 towards the edges of the substrate 210, and the absolute values of the deflection angles of the plurality of microlenses 220 can gradually increase from the preset axis 240 towards the edges of the substrate 210. The preset axis 240 can be the central axis of the substrate 210. The difference between the absolute values of the deflection angles of two adjacent microlenses 220 can be less than or equal to 0.1°.

[0096] Table 1 shows the θ, H and H / h of the microlenses corresponding to different values of a. It should be understood that there can be several microlenses between the microlenses corresponding to different values of a shown in Table 1, for example, there can be several microlenses between the microlenses corresponding to a = -8° and a = -4°. As shown in Table 1, the absolute value of the angle a between the principal axis I of the incident light ray corresponding to the microlens and the preset axis 240 gradually changes from the base edge to the base center, for example, |a| has a maximum value at the base edge, which can be 16°, and |a| has a minimum value at the base center, which can 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 base edge to the base center, for example, |θ| and H have maximum values at the base edge, for example, |θ| = 3.5° and H = 1.778 μm, and |θ| and H have minimum values at the base center, for example, |θ| = 0° and H = 0 μm.

[0097] Table 1

[0098] Embodiment 2

[0099] FIG. 11 shows a top view of a diffusion element 200 according to Embodiment 2 of the present application. FIG. 12 shows a-a sectional view of FIG. 11. FIG. 13 shows b-b sectional view of FIG. 11.

[0100] Referring to FIGS. 11-13, the diffusion element 200 can include a substrate 210 and a plurality of microlenses 220. The plurality of microlenses 220 can be arranged in an array along a first direction and a second direction on a second surface of the substrate 210. The diffusion element 200 has a size of 100 mm in the first direction and a size of 45 mm in the second direction. The diffusion element 200 has a preset diffusion angle FOV1 of 23° in the first direction and a preset diffusion angle FOV2 of 7° in the second direction. The microlenses 220 have a size of 20 μm in the first direction and the second direction.

[0101] In the first direction and the second direction, the step heights of the plurality of microlenses 220 can be asymmetrically distributed relative to the preset axis 240, and the absolute values of the deflection angles of the plurality of microlenses 220 can be asymmetrically distributed relative to the preset axis 240. In the first direction, the step heights of the plurality of microlenses 220 can 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 can gradually increase from the preset axis 240 to the edge of the substrate 210. The preset axis 240 can be spaced apart from the central axis of the substrate 210 by a certain distance. The difference between the absolute values of the deflection angles of two adjacent microlenses 220 can be less than or equal to 0.1°, for example, the difference between the absolute values of the deflection angles of two adjacent microlenses 220 in the first direction can be less than or equal to 0.06°. The difference between the absolute values of the deflection angles of two adjacent microlenses 220 in the second direction can be less than or equal to 0.03°.

[0102] Table 2 shows the θ, H and H / h of the microlenses corresponding to different α values in the first direction. It should be understood that there can be several microlenses between the microlenses corresponding to different α values shown in Table 2, for example, there can be several microlenses between the microlenses corresponding to α = -5° and α = -3°. As shown in Table 2, in the first direction, the angle α between the principal axis I of the incident light corresponding to the microlenses 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°.

[0103] Table 2

[0104] Table 3 shows the θ, H and H / h of the microlenses corresponding to different α values in the second direction. It should be understood that there can be several microlenses between the microlenses corresponding to different α values shown in Table 3, for example, there can be several microlenses between the microlenses corresponding to α = -20° and α = -18°. As shown in Table 3, in the second direction, the angle α between the principal axis I of the incident light corresponding to the microlenses 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] The second aspect of the present application provides a preparation method 1000 of a diffusion element, which can be used to form the diffusion element 200 of the first aspect of the present application.

[0107] FIG. 14 shows a flowchart of a preparation method 1000 of a diffusion element according to an example embodiment of the present application. Referring to FIG. 14, the preparation method 1000 can include the following steps:

[0108] S100, forming a plurality of microlenses on a side surface of a substrate; and

[0109] S200, adjusting the plurality of microlenses such that a distance from a position farthest from the substrate (e.g., a vertex C) of at least one microlens to a preset axis is less than a distance from a center of a surface close to the substrate of the microlens to the preset axis, the preset axis being parallel to a central axis of the substrate.

[0110] By disposing a plurality of microlenses on a side surface of a substrate, and a distance from a position farthest from the substrate (e.g., a vertex C) of at least one microlens to a preset axis being less than a distance from a center of a surface close to the substrate of the microlens to the preset axis, the microlens can be caused to deflect the diffusion of light toward the center of the substrate, and in the case of a diffusion element having a small diffusion angle, the diffusion element can be ensured to have a large diffusion area and high brightness, thereby facilitating the realization of a large eye box and high brightness of a projection system including the diffusion element. In addition, the preparation process difficulty and cost of the diffusion element 200 can also be reduced.

[0111] The steps S100 and S200 of the example embodiments of the present application are described below.

[0112] In this step S100, a plurality of microlenses are formed on a side surface of a substrate.

[0113] In an example embodiment, the substrate can include a first surface and a second surface disposed opposite to each other. The first surface can be, for example, a light incident surface. The second surface can be, for example, a light exit surface. The plurality of microlenses are formed on a side surface (e.g., the second surface) of the substrate, and the light diffusion portion can be, for example, a curved surface. The light diffusion portion can include a first end A and a second end B, the first end A can be away from the preset axis, and the second end B can be close to the preset axis. The absolute value of the curvature of the first end A can be less than or equal to the absolute value of the curvature of the second end B.

[0114] In an example embodiment, the plurality of microlenses can 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, the plurality of microlenses can be disposed on the second surface of the substrate along the first direction; or the plurality of microlenses can be disposed on the second surface of the substrate along the second direction; or the plurality of microlenses can be arrayed on the second surface of the substrate along the first direction and the second direction. For example, the plurality of microlenses can be disposed on the second surface of the substrate in, for example, an m row x n column manner, the first direction can be, for example, a row direction, and the second direction can be, for example, a column direction.

[0115] After forming the plurality of microlenses, the plurality of microlenses is adjusted in step S200 so that the distance from the position farthest from the substrate of at least one microlens to the preset axis is less than the distance from the center of the surface close to the substrate of the microlens to the preset axis, and the preset axis is parallel to the central axis of the substrate.

[0116] In an exemplary embodiment, the light diffusion portion of the plurality of microlenses is 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 the distance from the position farthest from the substrate of the microlens to the preset axis is less than the distance from the center of the surface close to the substrate of the microlens to the preset axis.

[0117] By controlling the distance from the position farthest from the substrate (for example, the vertex C) of at least one microlens to the preset axis to be less 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 in the case that the diffusion element has a smaller diffusion angle, the diffusion element can have a larger diffusion area 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 preparation process difficulty and cost of the diffusion element can also be reduced.

[0118] In an exemplary embodiment, the preparation method 1000 can further include adjusting the light diffusion portion 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 axis II of the emergent light ray from the microlens is inclined toward the direction close to the preset axis relative to the principal axis I of the incident light ray, in other words, there is an included angle between the principal axis II of the emergent light ray and the principal axis I of the incident light ray corresponding to the microlens, and the included angle between the principal axis II of the emergent light ray and the principal axis I of the incident light ray corresponding to the microlens can be referred to as the deflection angle θ of the microlens.

[0119] By making the principal axis II of the emergent light ray from at least one microlens inclined toward the direction close to the preset axis relative to the principal axis I of the incident light ray, the diffusion of light by the microlens can be deflected toward the center of the substrate, and in the case that the diffusion element has a smaller diffusion angle, the diffusion element can have a larger diffusion area 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 preparation process difficulty and cost of the diffusion element can also be reduced.

[0120] In the example embodiment, the preparation method 1000 can further include adjusting the light diffusion portion 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 two adjacent microlenses, so that the plurality of microlenses can satisfy |θ1|>|θ2|, where θ1 is the refraction angle of the microlens away from the preset axis in the at least two adjacent microlenses, and θ2 is the refraction angle of the microlens close to the preset axis in the at least two adjacent microlenses. The absolute value of the curvature of the first end A of the light diffusion portion can be less than or equal to the absolute value of the curvature of the second end B of the light diffusion portion.

[0121] The absolute value of the refraction angle of the microlens can be positively correlated with the difference between the absolute values of the curvatures of the first end A and the second end B of the light diffusion portion. In other words, the greater the difference between the absolute values of the curvatures of the first end A and the second end B of the light diffusion portion, the greater the refraction angle of the microlens; the smaller the difference between the absolute values of the curvatures of the first end A and the second end B of the light diffusion portion, the smaller the refraction angle of the microlens. When the difference between the absolute values of the curvatures of the first end A and the second end B of the light diffusion portion is 0, the refraction angle of the microlens can be 0°.

[0122] By controlling the plurality of microlenses to satisfy |θ1|>|θ2|, the microlenses close to the edge of the substrate can be caused to refract the diffusion of light toward the center of the substrate, and in the case where the diffusion element has a small diffusion angle, the diffusion element can be ensured to have a large diffusion area and high brightness. In addition, the at least two adjacent microlenses can also be caused to have different structure sizes, which is beneficial to weakening the Moiré phenomenon of the diffusion element, improving the imaging quality and uniformity of the diffusion element, and reducing the preparation process difficulty and cost of the diffusion element.

[0123] In the example embodiment, the preparation method 1000 can further include connecting the second end B of the light diffusion portion of one microlens and the first end A of the light diffusion portion of another microlens adjacent to the one microlens. In other words, the height difference of the one microlens can be 0 μm.

[0124] In the example embodiment, the preparation method 1000 can further include forming a connecting portion. The connecting portion can extend from the second end B of the light diffusion portion of one microlens toward the substrate, and the side of the connecting portion close to the substrate is connected to the first end A of the light diffusion portion of another microlens adjacent to the one microlens. In other words, the height difference of the one microlens can be greater than 0 μm.

[0125] In the example embodiment, the preparation method 1000 can further comprise adjusting the light diffusion portion 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 in the first direction and / or the second direction, and causing the principal axis II of the emergent light ray from the at least one microlens to be deflected relative to the principal axis I of the incident light ray, and accordingly, the center of the preset diffusion plane of the microlens can 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 plane of at least one microlens (for example, the 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 the at least one microlens can be greater than 0°. The overlapping area of the preset diffusion planes of the microlenses located at the opposite edges of the substrate can be the eyebox area. By controlling the deflection of the center of the preset diffusion plane of the microlens close to the edge of the substrate relative to the center of the surface of the microlens close to the substrate, in the case of a diffusion element with a smaller diffusion angle, the diffusion element can have a larger diffusion plane and higher brightness, thereby facilitating the realization of a large eyebox and high brightness of a projection system comprising the diffusion element.

[0126] In the example embodiment, the preparation method 1000 can further comprise adjusting the light diffusion portion 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 two adjacent microlenses, and causing the absolute values of the deflection angles of the at least two microlenses to be different in the first direction and / or the second direction. By controlling the absolute values of the deflection angles of the at least two adjacent microlenses to be different, the at least two adjacent microlenses can have different structural sizes, which is beneficial to weaken the Moiré fringe phenomenon of the diffusion element and improve the imaging quality and uniformity of the diffusion element.

[0127] In the example embodiment, the preparation method 1000 can further comprise adjusting the light diffusion portion of the plurality of microlenses, for example, adjusting the light diffusion portion of at least two adjacent microlenses, and causing the step heights of the at least two microlenses to be different in the first direction and / or the second direction. By controlling the step heights of the at least two adjacent microlenses to be different, the at least two adjacent microlenses can have different structural sizes, which is beneficial to weaken the Moiré fringe phenomenon of the diffusion element and improve the imaging quality and uniformity of the diffusion element.

[0128] In an example embodiment, the preparation method 1000 can further include adjusting the light diffusion portion of the plurality of microlenses, and causing the plurality of microlenses to satisfy H1>H2, where H1 is the height difference of the microlens farther from the preset axis among at least two adjacent microlenses, and H2 is the height difference of the microlens closer to the preset axis among the at least two adjacent microlenses. By causing the at least two adjacent microlenses to have different height differences, and causing the microlenses closer to the edge of the base to have a greater height difference than the microlenses closer to the center of the base, the microlenses closer to the edge of the base can be caused to produce a greater deflection of the diffusion of light, and in the case of a diffusion element having a smaller diffusion angle, the diffusion element can be ensured to have a larger diffusion area and higher brightness.

[0129] In an example embodiment, the preparation method 1000 can further include adjusting the light diffusion portion of the microlenses, and causing the microlenses to satisfy 0≤H / h≤1, where H is the height difference of the microlenses, and h is the sag of the microlenses. By causing the ratio of the height difference of the microlenses to the sag to be within the range of 0 to 1, the large eyebox and high brightness of a projection system including the diffusion element can be facilitated.

[0130] In an example embodiment, the preparation method 1000 can further include adjusting the light diffusion portion of the plurality of microlenses, and causing the plurality of microlenses to satisfy H1 / h1>H2 / h2, where H1 is the height difference of the microlens farther from the preset axis among at least two adjacent microlenses, h1 is the sag of the microlens farther from the preset axis among the at least two adjacent microlenses, H2 is the height difference of the microlens closer to the preset axis among the at least two adjacent microlenses, and h2 is the sag of the microlens closer to the preset axis among the at least two adjacent microlenses. By causing the ratio of the height difference to the sag of the at least two adjacent microlenses to be different, and causing the microlenses closer to the edge of the base to have a greater ratio of the height difference to the sag than the microlenses closer to the center of the base, the microlenses closer to the edge of the base can be caused to produce a greater deflection of the diffusion of light, and in the case of a diffusion element having a smaller diffusion angle, the diffusion element can be ensured to have a larger diffusion area and higher brightness.

[0131] In the example embodiment, the preparation method 1000 can further comprise adjusting the light diffusion part of the plurality of microlenses, and 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. 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 gradually change from the preset axis to the edge of the substrate, so that the microlenses near the edge of the substrate produce greater deflection to the diffusion of light, the microlenses near the center of the substrate produce smaller deflection or no deflection to the diffusion of light, and in the case of a smaller diffusion angle of the diffusion element, the diffusion element has a larger diffusion area and higher brightness. In addition, when the height difference of the plurality of microlenses in the first direction and the second direction gradually changes at the same time, the microlenses near the edge of the substrate in the two directions produce greater deflection to the diffusion of light, the diffusion angle of the diffusion element in the two directions is reduced, and the diffusion element has a larger diffusion area and higher brightness in the two directions.

[0132] In the example embodiment, the preparation method 1000 can further comprise adjusting the light diffusion part of the plurality of microlenses, and in the first direction and / or the second direction, the height difference of the plurality of microlenses is symmetrically distributed relative to the preset axis; and the absolute value of the deflection angle of the plurality of microlenses is symmetrically distributed relative to the preset axis.

[0133] In the example embodiment, the preparation method 1000 can further comprise adjusting the light diffusion part of the plurality of microlenses, and in the first direction and / or the second direction, the height difference of the plurality of microlenses is asymmetrically distributed relative to the preset axis; and the absolute value of the deflection angle of the plurality of microlenses is asymmetrically distributed relative to the preset axis.

[0134] In the example embodiment, the preparation method 1000 can further comprise adjusting the plurality of microlenses, and the plurality of microlenses satisfy: 0<(|θ1|-|θ2|)×50<FOV, wherein θ1 is the deflection angle of the microlens away from the preset axis in at least two adjacent microlenses, θ2 is the deflection angle of the microlens close to the preset axis in 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 the microlenses near the edge of the substrate have larger deflection angles than the microlenses near the center of the substrate, the microlenses near the edge of the substrate can produce greater deflection to the diffusion of light, and in the case of a smaller diffusion angle of the diffusion element, the diffusion element has a larger diffusion area and higher brightness. At the same time, the structures and sizes of the two adjacent microlenses are different, thereby inhibiting the Moiré phenomenon of the diffusion element, improving the imaging quality and uniformity of the diffusion element, and reducing the cost.

[0135] In an example embodiment, the preparation method 1000 can further include adjusting the light diffusion portion of the microlens, and causing the microlens to satisfy: (0.44-0.004x(|a|-8))x|0| x(L / 20)≤Hx1°x1°≤(0.84-0.004x(|a|-8))x|0| x(L / 20), where H is the height difference of the microlens; a is the included angle between the principal axis I of the incident light ray corresponding to the microlens and the preset axis; 0 is the refraction angle of the microlens; and L is the size of the microlens. By restricting the height difference of the microlens within the above range, the diffraction effect of the microlens can be inhibited in the case that the microlens has a proper refraction angle, which is conducive to ensuring that the projection system including the diffusion element achieves a large eyebox and high brightness, and improving the imaging quality of the projection system, for example, the projection picture of the projection system is free of rainbow stripes.

[0136] In an example embodiment, the preparation method 1000 can further include adjusting the light diffusion portion of the microlens, and causing the microlens to satisfy: 0≤H / (|0| x L) x 1°≤0.035, where H is the height difference of the microlens; 0 is the refraction angle of the microlens; and L is the size of the microlens. As an example, 0.0015≤H / (|0| x L) x 1°≤0.035. By controlling the above conditional expression, the diffraction effect of the microlens can be inhibited in the case that the microlens has a proper refraction angle, which is conducive to ensuring that the projection system including the diffusion element achieves a large eyebox and high brightness, and improving the imaging quality of the projection system, for example, the projection picture of the projection system is free of rainbow stripes.

[0137] In an example embodiment, the preparation method 1000 can further include adjusting the light diffusion portion of the microlens in the first direction and / or the second direction, and causing the preset diffusion surfaces of the microlenses located at the opposite side edges of the substrate to substantially coincide, for example, the coinciding area of the preset diffusion surfaces of the microlenses located at the opposite side edges of the substrate is about 95% or above of the area of the preset diffusion surface. By controlling the diffusion of the microlenses at the opposite side edges of the substrate to be deflected towards the center of the substrate at the same time, the waste of light can be reduced, and in the case that the diffusion element has a smaller diffusion angle, the diffusion element is ensured to have a larger diffusion surface and higher brightness.

[0138] A third aspect of the present application provides a projection system. The projection system can be, for example, a head-up display system. The projection system can 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 can be configured to emit image light carrying image information. The diffusion element can be configured to diffuse the image light to form diffusion light. The projection module can be configured to project the diffusion light, for example, to an eyebox region.

[0139] The above description is only the preferred embodiment of the present application and the explanation of the technical principles. It should be understood by those skilled in the art that the scope of the protection of the present application is not limited to the technical solutions formed by the specific combinations of the technical features disclosed above, and should also cover other technical solutions formed by the combinations of the technical features disclosed above or their equivalent features without departing from the concept of the present application. For example, the above features are replaced by the technical features with similar functions disclosed in the present application (but not limited to) to form the technical solutions.

Claims

1. A diffusion element, characterized by, The application relates to a diffusion element, comprising: a substrate; and a plurality of microlenses arranged on one side surface of the substrate; wherein the distance from the farthest position of at least one microlens to a preset axis is less 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.

2. The diffusion element of claim 1, wherein, The main optical axis of the emergent light ray from at least one microlens is inclined to the direction close to the preset axis relative to the main optical axis of the incident light ray.

3. The diffusion element according to claim 1 or 2, wherein The plurality of microlenses satisfy: |θ1|> |θ2|, wherein θ1 is the deflection angle of the microlens far from the preset axis in at least two adjacent microlenses, and θ2 is the deflection angle of the microlens close to the preset axis in at least two adjacent microlenses, and the deflection angle of the microlens is the included angle between the main optical axis of the corresponding emergent light ray and the main optical axis of the incident light ray.

4. The diffusion element according to any one of claims 1 to 3, wherein The microlens comprises: a light diffusion part, comprising a first end far from the preset axis and a second end close to the preset axis; wherein the height difference of at least one microlens is greater than 0 microns, and the height difference of the microlens is the distance from the second end of 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.

5. The diffusion element according to any one of claims 1 to 4, wherein The absolute value difference of the curvatures of the first end and the second end of the light diffusion part of the plurality of microlenses gradually increases from the preset axis to the edge of the substrate.

6. The diffusion element according to any one of claims 1 to 5, wherein The diffusion element further comprises: a connecting part extending from the second end of the light diffusion part of one microlens to the direction close to the substrate, and the side close to the substrate of the connecting part is connected with the first end of the light diffusion part of another microlens adjacent to the microlens.

7. The diffusion element according to any one of claims 1 to 6, wherein The height difference of at least one microlens close to the preset axis is equal to 0 microns.

8. The diffusion element according to any one of claims 1 to 7, 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 both are parallel to the surface of the substrate provided with the microlenses.

9. The diffusion element according to any one of claims 1 to 8, wherein, In the first direction and / or the second direction, the center of the preset diffusion surface of at least one microlens is closer to the preset axis than the center of the surface close to the substrate of the microlens.

10. The diffusion element according to any one of claims 1 to 9, wherein, In the first direction and / or the second direction, the height differences of at least two microlenses are different, and the absolute values of the deflection angles of the at least two microlenses are different, wherein the deflection angle of the microlens is the included angle between the main optical axis of the corresponding emergent light ray and the main optical axis of the incident light ray.

11. The diffusion element according to any one of claims 1 to 10, wherein In the first direction and / or the second direction, the height differences of the plurality of microlenses gradually increase from the preset axis to the edge of the substrate, and the absolute values of the deflection angles of the plurality of microlenses gradually increase from the preset axis to the edge of the substrate.

12. The diffusion element according to any one of claims 1 to 11, wherein, In the first direction and / or the second direction, the height differences of the plurality of microlenses are symmetrically distributed relative to the preset axis, or asymmetrically distributed; and the absolute values of the deflection angles of the plurality of microlenses are symmetrically distributed relative to the preset axis, or asymmetrically distributed.

13. The diffusion element according to any one of claims 1 to 12, wherein, The plurality of microlenses satisfy: 0 < (|θ1| - |θ2|) x 50 < FOV, wherein FOV is a preset diffusion angle of the diffusion element.

14. The diffusion element according to any one of claims 1 to 13, wherein, The plurality of microlenses satisfy: H1 > H2, wherein H1 is a height difference of the microlens far from the preset axis in at least two adjacent microlenses, and H2 is a height difference of the microlens close to the preset axis in at least two adjacent microlenses.

15. The diffusion element according to any one of claims 1 to 14, wherein, The microlens satisfies: 0 ≤ H / h ≤ 1, wherein H is a height difference of the microlens; and h is a sag height of the microlens, which is a distance from a position farthest from the base in a light diffusion part of the microlens to a first end of another light diffusion part adjacent to a second end of the light diffusion part.

16. The diffusion element according to any one of claims 1 to 15, wherein, The plurality of microlenses satisfy: H1 / h1 > H2 / h2, wherein H1 is a height difference of the microlens far from the preset axis in at least two adjacent microlenses, h1 is a sag height of the microlens far from the preset axis in at least two adjacent microlenses, H2 is a height difference of the microlens close to the preset axis in at least two adjacent microlenses, and h2 is a sag height of the microlens close to the preset axis in at least two adjacent microlenses.

17. The diffusion element according to any one of claims 1 to 16, wherein, The microlens satisfies: (0.44-0.004x(|α|-8))x|θ|x(L / 20) ≤ Hx1°x1° ≤ (0.84-0.004x(|α|-8))x|θ|x(L / 20), wherein H is a height difference of the microlens; α is an included angle between a principal axis of an incident light corresponding to the microlens and the preset axis; θ is a refraction angle of the microlens, which is an included angle between a principal axis of an outgoing light corresponding to the microlens and a principal axis of the incident light; and L is a size of the microlens.

18. The diffusion element according to any one of claims 1 to 17, wherein, The microlens satisfies: 0 ≤ H / (|θ|xL)x1° ≤ 0.035, wherein H is a height difference of the microlens; θ is a refraction angle of the microlens, which is an included angle between a principal axis of an outgoing light corresponding to the microlens and a principal axis of the incident light; and L is a size of the microlens.

19. The diffusion element according to any one of claims 1 to 18, wherein, The preset diffusion surfaces of the microlenses located at opposite side edges of the base coincide.

20. A method of producing a diffusion element as claimed in any one of claims 1 to 19, characterised in that, Comprising: forming a plurality of microlenses on a side surface of a base; and adjusting the plurality of microlenses so that a distance from a position farthest from the base of at least one microlens to a preset axis is less than a distance from a center of a surface close to the base of the microlens to the preset axis, the preset axis being parallel to a central axis of the base.

21. A method of producing a diffusion element, characterized by, Comprising: forming a plurality of microlenses on a side surface of a base; and adjusting the plurality of microlenses so that a distance from a position farthest from the base of at least one microlens to a preset axis is less than a distance from a center of a surface close to the base of the microlens to the preset axis, the preset axis being parallel to a central axis of the base.

22. A projection system, characterized by Comprising: an image generation module configured to emit image light carrying image information; The diffusion element of any one of claims 1 to 19 for diffusing the image light to form a diffuse light; and a projection module for projecting the diffuse light.

Images