Diffuser plate and its manufacturing method and projection system

Abstract

The present application discloses a diffusion plate, a manufacturing method thereof, and a projection system. The diffusion plate according to the embodiment of the present application may include a substrate having a first surface; and a microlens array, which is arranged on the substrate, wherein the microlens array includes a plurality of microlenses arranged continuously in a first direction and a second direction along the first surface, wherein the first direction is perpendicular to the second direction; wherein each microlens includes a bottom surface facing the first surface, and a curved surface opposite to the bottom surface; the maximum heights of the plurality of microlenses in the microlens array are different, and in the microlens array, any two adjacent microlenses satisfy the following conditions: 3 / 20≤ΔH / L≤1 / 4, wherein ΔH is the absolute value of the difference in the maximum heights of the two adjacent microlenses, L is the maximum length or maximum width of any microlens of the two adjacent microlenses, and the maximum height is the distance from the vertex of the curved surface of each microlens to the bottom surface.

Description

Technical Field

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

[0002] An optical diffuser is an optical device that evenly distributes the intensity of incident light within a certain range of space. Among them, the microlens array diffuser can properly diffuse the incident light and freely design the required diffusion angle, so it is widely used in laser projectors, laser radars, HUD (Head Up Display) and other systems.

[0003] When the microlens array diffuser is used with a PGU (Picture Generation Unit) such as DLP (Digital Light Processing), LCOS (Liquid Crystal On Silicon), MEMS (Micro-Electro-Mechanical System), or LBS (Laser Beam Scanning), it mainly acts as a screen in the vehicle-mounted HUD system or AR (Augmented Reality)-HUD system.

[0004] For the diffuser, the diffraction phenomenon needs to be suppressed to achieve uniform diffusion of the entire light field, thereby realizing the function of a screen. At present, most diffusers achieve the anti-diffraction effect by combining the non-periodic position of the microlens with the irregular configuration of the microlens curvature radius, but this method easily causes the diffuser to have a noticeable grainy appearance and reduces the image clarity.

[0005] Therefore, how to make the diffuser plate suppress the diffraction phenomenon well and improve the imaging clarity is crucial for the application of the diffuser plate in projection systems such as vehicle-mounted HUD systems. Summary of the invention

[0006] On the one hand, an embodiment of the present application provides a diffusion plate, which may include a substrate having a first surface; and a microlens array, which is arranged on the substrate, the microlens array including a plurality of microlenses continuously arranged in a first direction and a second direction along the first surface, wherein the first direction is perpendicular to the second direction; wherein each microlens includes a bottom surface facing the first surface, and a curved surface opposite to the bottom surface; the maximum heights of the plurality of microlenses in the microlens array are different, and in the microlens array, any two adjacent microlenses satisfy the following condition: 3 / 20≤ΔH / L≤1 / 4, wherein ΔH is the absolute value of the difference in maximum heights of two adjacent microlenses, L is the maximum length or maximum width of any microlens of the two adjacent microlenses, and the maximum height is the distance from the vertex of the curved surface of each microlens to the bottom surface.

[0007] In an exemplary embodiment, the bottom surfaces of the microlenses in the microlens array are of the same shape and size, the bottom surfaces centers of any adjacent microlenses in a first direction are aligned along the first direction, and the bottom surfaces centers of any adjacent microlenses in a second direction are aligned along the direction.

[0008] In an exemplary embodiment, the bottom surface of each microlens in the microlens array is rectangular in shape.

[0009] In an exemplary embodiment, in a microlens array, the surface shape difference between any two adjacent microlenses is greater than zero and not greater than 15%, wherein the surface shape difference refers to the ratio of the absolute value of the difference between the derivatives of the surface shapes of two adjacent microlenses to the derivative of the surface shape of any one of the microlenses.

[0010] In an exemplary embodiment, in the microlens array, the projection of the position where the maximum value of the surface shape difference between any two adjacent microlenses is located is located within a ±10% area of ​​the center of the bottom surface of any one of the microlenses.

[0011] In an exemplary embodiment, in a microlens array, the difference in surface shape at corresponding positions within a boundary region between any two adjacent microlenses is greater than zero and not greater than 2%, wherein the boundary region refers to an area outside a central region of the microlens, and a distance from a projection position of any point within the central region to the center of a bottom surface of the microlens does not exceed 20% of a maximum length or a maximum width of the bottom surface.

[0012] In an exemplary embodiment, in the microlens array, each microlens has the same radius of curvature in the first direction and the same radius of curvature in the second direction.

[0013] In an exemplary embodiment, in the microlens array, any two adjacent microlenses satisfy the following condition: ΔM / ΔH≤1, where ΔM is the absolute value of the difference in magnification of the two adjacent microlenses.

[0014] In an exemplary embodiment, the length and width of each microlens are between 16 μm and 22 μm.

[0015] In an exemplary embodiment, in the microlens array, an absolute value ΔH of a difference between maximum heights of any two microlenses is ≤5 μm.

[0016] In addition, according to an embodiment of the present application, a method for manufacturing a diffuser plate is also provided, the method comprising: setting a substrate, the substrate having a first surface; and continuously arranging a plurality of microlenses on the substrate along a first direction and a second direction of the first surface to form a microlens array, wherein the first direction is perpendicular to the second direction; each microlens comprises a bottom surface facing the first surface, and a curved surface opposite to the bottom surface; the method further comprises: setting different maximum heights for the plurality of microlenses in the microlens array, respectively, and in the microlens array, any two adjacent microlenses satisfy the following conditions: 3 / 20≤ΔH / L≤1 / 4, wherein ΔH is the absolute value of the difference in maximum heights between two adjacent microlenses, L is the maximum length or maximum width of any one of the two adjacent microlenses, and the maximum height is the distance from the vertex of the curved surface of each microlens to the bottom surface.

[0017] In addition, according to an embodiment of the present application, a projection system is also provided, which includes a light source and the diffusion plate as described above, and the light beam emitted by the light source is diffused by the diffusion plate to form a uniform light field intensity.

[0018] In one exemplary embodiment, the projection system may include a heads-up display system.

[0019] As described above, according to the diffusion plate provided by one or more embodiments of the present application, the plurality of microlenses of the microlens array have different maximum heights.

[0020] In addition, in some embodiments of the present application, any microlens on the diffusion plate is consistent in size with its surrounding adjacent microlenses and aligned in position, so the center misalignment is zero, thereby reducing the diffusion difference between different pixels and improving imaging clarity.

[0021] In addition, in some embodiments of the present application, continuous random heights are added to microlenses of the same height to create height differences between microlenses, thereby avoiding a periodic arrangement of microlenses in space and suppressing diffraction.

[0022] In addition, in some embodiments of the present application, the plurality of microlenses in the microlens array have regularly configured curvature radii. By regularly configuring the curvature radii of the microlenses, the magnification difference between the microlenses can be reduced, thereby improving the imaging clarity.

[0023] In addition, in some embodiments of the present application, by controlling the difference in surface shape between adjacent microlenses, the difference in magnification between adjacent microlenses can be reduced, thereby improving imaging clarity. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Other features, objects and advantages of the present application will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings:

[0025] Figure 1 A schematic top view of a microlens of a non-diffractive diffuser plate according to the related art is shown;

[0026] Figure 2 Shows Figure 1 Schematic diagram of a horizontal cross section of a microlens of an anti-diffraction diffuser plate;

[0027] Figure 3 Shows Figure 1 Schematic diagram of the imaging effect of the anti-diffraction diffuser;

[0028] Figure 4a and Figure 4b A schematic diagram of the composition structure of a diffuser plate according to an exemplary embodiment of the present application is shown;

[0029] Figure 5 Shows Figure 4a and Figure 4b Schematic diagram of the structure of a single microlens of the diffuser plate;

[0030] Figure 6a Shows Figure 4a and Figure 4b Schematic diagram of a diffuser plate in which microlenses have different maximum heights;

[0031] Figure 6b Shows Figure 4a and Figure 4b Schematic diagram of the periodic arrangement of micro lenses of the diffuser plate;

[0032] Figure 6c Shows Figure 4a and Figure 4b Schematic diagram of the central area and the boundary area of ​​the microlens of the diffusion plate;

[0033] Figure 6d Shows Figure 4a and Figure 4b Schematic diagram of a diffuser plate in which microlenses have regularly configured curvature radii;

[0034] Figure 7 Shows Figure 4a and Figure 4b Schematic diagram of the imaging effect of the diffuser plate in FIG.

[0035] Figure 8 A schematic top view of a microlens of a diffusion plate according to a first embodiment of the present application is shown;

[0036] Fig. 9 A schematic diagram showing the random heights added to the microlenses in the first region in the first embodiment of the present application is shown;

[0037] Fig.10 A schematic diagram showing the diffraction effect in the first region in the first embodiment of the present application is shown;

[0038] Fig.11 A schematic diagram showing the difference in surface shapes of adjacent microlenses in the first embodiment of the present application;

[0039] Fig.12 A schematic diagram showing the imaging effect of the diffusion plate of the first embodiment of the present application is shown;

[0040] Fig.13 A schematic top view of a microlens of a diffusion plate according to a second embodiment of the present application is shown;

[0041] Fig.14 A schematic diagram showing the random heights added to the microlenses in the second region in the second embodiment of the present application;

[0042] Fig.15 A schematic diagram showing the diffraction effect in the second region in the second embodiment of the present application is shown;

[0043] Fig.16 A schematic diagram showing the difference in surface shapes of adjacent microlenses in the second embodiment of the present application;

[0044] Fig.17 A schematic diagram showing the imaging effect of the diffusion plate of the second embodiment of the present application is shown;

[0045] Fig.18 A schematic diagram showing the deflection angle of the diffuser plate of the second embodiment of the present application; and

[0046] Fig.19 A schematic flow chart of a method for manufacturing a diffusion plate according to a third embodiment of the present application is shown.

[0047] In the accompanying drawings, the descriptions of the reference numerals are as follows:

[0048] 100 - diffuser plate; 10 - microlens; 11 - substrate; 110 - bottom surface; 120 - curved surface. DETAILED DESCRIPTION

[0049] In order to better understand the present application, various aspects of the present application will be described in more detail 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 do not limit the scope of the present application in any way. Throughout the specification, the same figure numbers refer to the same elements. The expression "and / or" includes any one of the relevant listed items and any combination of any two or more. It is understood that the specific embodiments described herein are only used to explain the relevant inventions, rather than to limit the invention. It should also be noted that, for ease of description, only the parts related to the relevant inventions are shown in the accompanying drawings.

[0050] It should be noted that in this specification, the expressions first, second, third, etc. are only used to distinguish one feature from another, but do not represent any limitation on the features, and especially do not represent any order of precedence.

[0051] 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.

[0052] Throughout the specification, when, for example, an element is described as being “on,” “connected to,” or “coupled to” another element, the element may be directly “on,” “connected to,” or “coupled to” the other element, or one or more other elements may be present between the element and the other element. Conversely, when an element is described as being “directly on,” “directly connected to,” or “directly coupled to” another element, other elements may not be present between the element and the other element.

[0053] For ease of description, spatially relative terms such as "above," "higher," "lower," and "lower" may be used herein to describe the relationship of one element to another element as shown in the accompanying drawings. Such spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation depicted in the accompanying drawings. For example, if the device in the accompanying drawings is turned over, an element described as being "above" or "higher" relative to another element will be "below" or "lower" relative to the other element. Therefore, depending on the spatial orientation of the device, the term "above" includes both "above" and "lower" orientations. The device may also be oriented in other ways (e.g., deflected 90 degrees or in other orientations), and the spatially relative terms used herein should be interpreted accordingly.

[0054] It should also be understood that the terms "comprises", "including", "having", "includes" and / or "comprising", when used in this specification, indicate the presence of the 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, when a statement such as "at least one of..." appears after a list of listed features, it modifies all of the features in the list, rather than just the individual elements in the list.

[0055] As used herein, the words "substantially," "approximately," "about," "substantially," and similar words are used as words of approximation rather than words of degree, and are intended to account for the inherent variations in measurements or calculations that one of ordinary skill in the art would recognize.

[0056] Unless otherwise defined, all terms (including technical and scientific terms) used herein 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 interpreted as having 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 article.

[0057] refer to Figure 1 and Figure 2 As shown, according to the related art, the diffuser plate with anti-diffraction function has a non-periodic arrangement of microlenses, for example, the bottom shape of the microlenses is irregular, or the arrangement positions between the microlenses are not aligned. Therefore, there is a misalignment amount (referred to as the center misalignment amount in this article) between the centers of each microlens. The center of the microlens may refer to the center of the bottom shape of the microlens, or to the center of the curved surface of the surface opposite to the bottom of the microlens. In addition, the plurality of microlenses in the diffuser plate according to the related art generally have irregularly configured curvature radii, for example, the curvature radii of the plurality of microlenses are different, or are not completely the same.

[0058] The above-mentioned diffuser has the following two shortcomings: on the one hand, the non-periodic position arrangement of the microlenses will cause the microlenses to be misaligned, resulting in a center misalignment, which will cause the diffuser to have a noticeable grainy appearance, thereby reducing the image clarity; on the other hand, the irregular configuration of the curvature radius of the microlenses will cause a large difference in the surface shape between adjacent microlenses, thereby increasing the magnification difference between the microlenses, which will also reduce the image clarity. Figure 3 As shown, the imaging effect of this type of diffuser is often more granular and has poor imaging clarity.

[0059] The diffuser plate and its manufacturing method provided by the present application can at least solve or partially solve at least one problem or other problems existing in the above-mentioned existing diffuser plates. The features, principles and other aspects of the present application will be described in detail below with reference to the drawings and in combination with specific embodiments.

[0060] like Figure 4a , Figure 4b and Figure 5 As shown, according to an exemplary embodiment of the present application, a diffusion plate 100 is provided, including a substrate 11 and a microlens array disposed on the substrate 11. The microlens array can be formed on the substrate 11, or can also be formed integrally with the substrate 11.

[0061] The substrate 11 may have a first surface, which may be a main surface of the substrate. The substrate 11 may have a thin plate-like structure, and the first surface thereof may be a plane.

[0062] The microlens array includes a plurality of microlenses 10, and the plurality of microlenses 10 are periodically arranged along the first surface of the substrate 11. Exemplarily, the plurality of microlenses 10 are continuously arranged along the first direction and the second direction of the first surface to form a microlens array. The first direction may be perpendicular to the second direction, for example, the first direction may be expressed as the X direction, and the second direction may be expressed as the Y direction.

[0063] like Figure 5 As shown, each microlens 10 may have a bottom surface 110 facing the first surface (eg, the main surface) of the substrate 10 , and a curved surface 120 opposite to the bottom surface 110 .

[0064] In an exemplary embodiment, the bottom surface 110 of the microlens has a regular shape, such as a rectangle or a square, and the length of the bottom surface of the rectangle or square is L and the width is W.

[0065] In an exemplary embodiment, the curved surface 120 of the microlens 10 may be a spherical surface, an aspherical surface, or a free-form surface.

[0066] In an exemplary embodiment, the plurality of microlenses 10 of the microlens array have different maximum heights H, wherein the maximum height H refers to a vertical distance from the vertex of the curved surface 120 of the microlens to the bottom surface 110 .

[0067] Combination Figure 6a As shown, continuous random heights can be added to microlenses of the same height to generate a height difference ΔH between the microlenses. In this way, the periodic arrangement structure of the microlenses in space can be avoided, thereby achieving the effect of suppressing the diffraction phenomenon.

[0068] Exemplarily, the bottom surface shape and size of each microlens in the microlens array are the same, and the bottom surface centers of each microlens are aligned in the first direction and the second direction, respectively. Specifically, the bottom surface centers of any adjacent microlenses in the first direction are aligned along the first direction, and the bottom surface centers of any adjacent microlenses in the second direction are aligned along the second direction. In this way, multiple rows and columns of microlenses are arranged in a periodic array, thereby forming a microlens array with a periodic arrangement structure. In the microlens array, adjacent microlenses can be attached to each other. Reference Figure 6b Any microlens 10 on the diffusion plate is consistent in size with its surrounding adjacent microlenses and aligned in position, so the center misalignment is zero, thereby reducing the diffusion difference between different pixels and improving the imaging clarity.

[0069] In some exemplary embodiments, the curved surface 120 of the microlens 10 is an aspherical surface, wherein the surface shape of the aspherical surface can be expressed by the following formula (1).

[0070] (1)

[0071] The bottom surface of the microlens is used as the reference surface, and the center point of the bottom surface of the microlens is used as the origin to establish a three-dimensional rectangular coordinate system. z is the height of any point on the curved surface of the microlens from the reference surface, and the central axis of the microlens is used as the origin. rx is the distance from the central axis along the X direction, ry is the distance from the center axis along the Y direction, Cx is the curvature in the X direction (XZ plane) (unit: 1 / μm), Cy is the curvature in the Y direction (YZ plane) (unit: 1 / μm), kx is the cone coefficient in the X direction (XZ plane), ky is the cone coefficient in the Y direction (YZ plane).

[0072] In some exemplary embodiments, the surface shape difference between any two adjacent microlenses in the microlens array may satisfy the following condition: the surface shape difference between two adjacent microlenses is greater than zero and not greater than 15%, wherein the surface shape difference refers to the ratio of the absolute value of the difference between the derivatives of the surface shapes of two adjacent microlenses to the derivative of the surface shape of any one of the microlenses.

[0073] Exemplarily, the derivative of the surface shape of each microlens may include a derivative in the X direction: dz / dx and the derivative in the Y direction dz / dy ,in dz / dx and dz / dy They can be obtained using the following formulas (2) and (3) respectively.

[0074] (2)

[0075] (3)

[0076] By satisfying the above conditions and controlling the difference in surface shape between any two adjacent microlenses, the difference in magnification of adjacent microlenses can be reduced, thereby improving imaging clarity.

[0077] In some exemplary embodiments, any two adjacent microlenses in the microlens array may also satisfy at least one of the following conditions:

[0078] Condition 1: The projection of the position where the maximum difference in surface shape between adjacent microlenses is located is within the ±10% area of ​​the center of the bottom surface of any microlens, where the positive and negative signs of the area represent the positive and negative axis directions of the coordinate axis corresponding to the XY plane. For example, the -10% area can be understood as the negative axis area of ​​the X axis (Y axis);

[0079] Condition 2: The surface shape differences between adjacent microlenses are symmetrical about the bottom center of any microlens;

[0080] Condition 3: The surface shape difference at the corresponding position in the boundary area of ​​adjacent microlenses is greater than zero and not greater than 2%, refer to Figure 6c As shown, the boundary area (such as Figure 6c The shaded area in the figure refers to the area outside the central area of ​​the microlens, where the projection position of any point in the central area to the center of the bottom surface of the microlens (point o ) does not exceed 20% of the maximum length or maximum width of the bottom surface. That is, the distance between the projection position of any point in the boundary area and the outermost boundary of the bottom surface of the microlens (for example, the bottom edge of the microlens) does not exceed 30% (for example, 30%*L or 30%*W) of the maximum length or maximum width in that direction. Here, the surface shape difference amount at the corresponding position refers to the surface shape difference amount at the same position corresponding to two adjacent microlenses.

[0081] By performing the above-mentioned constraints and controls on the surface shape differences between adjacent microlenses, it is possible to ensure that the surface shape differences between adjacent microlenses are small, thereby improving imaging clarity.

[0082] refer to Figure 6d As shown, according to the diffuser plate of the exemplary embodiment of the present application, the surfaces 120 of the plurality of microlenses 10 in the microlens array have a regularly configured curvature radius R. By regularly configuring the curvature radius R of the microlens surface, the magnification difference between the microlenses can be reduced, thereby improving the imaging clarity. Figure 6d In order to better illustrate the regular configuration of the curvature radius of the microlenses, the height difference between the microlenses is adjusted so that the maximum height of each microlens tends to be consistent, but this should not be regarded as a limiting embodiment of the present application.

[0083] In some exemplary embodiments, the curved surfaces 120 of the plurality of microlenses 10 have the same radius of curvature Rx in the first direction (X direction) and the same radius of curvature Ry in the second direction (Y direction). Further, the radius of curvature Rx of the curved surface 120 of the microlens 10 in the X direction may be the same as or different from the radius of curvature Ry in the Y direction.

[0084] Among them, the magnification of the microlens refers to the diffusion angle corresponding to each microlens, and the magnification difference between microlenses is the difference in diffusion angles of adjacent microlenses. Since the radius of curvature is related to the magnification of the microlens, under the premise that other parameters are the same, the "regular configuration of the radius of curvature" means that the magnification of each microlens is the same. The setting of the radius of curvature R is related to the diffusion angle of the diffuser in the horizontal / vertical direction (for example, the X direction / Y direction). In actual applications, according to the different diffusion angle requirements in the horizontal / vertical direction, the radius of curvature R values ​​in the two directions (for example, the X direction and the Y direction) can be set to be different.

[0085] In some exemplary embodiments, any two adjacent microlenses in the microlens array satisfy the following condition: ΔM / ΔH≤1, where ΔM is the absolute value of the difference in magnification between two adjacent microlenses (magnification difference may also be referred to as magnification difference), and ΔH is the absolute value of the difference in maximum height between adjacent microlenses (magnification difference may also be referred to as height difference). Since the maximum height of a microlens is also related to the magnification, the greater the height difference ΔH between adjacent microlenses, the greater the magnification difference. Therefore, in order to suppress the obvious graininess of the appearance of the diffuser plate, the height difference ΔH needs to be controlled within a certain range.

[0086] In some exemplary embodiments, any two microlenses in the microlens array satisfy the following condition: 3 / 20≤ΔH / L≤1 / 4, where ΔH is the absolute value of the difference between the maximum heights of two adjacent microlenses, and L is the maximum length or maximum width of any microlens in the two adjacent microlenses. By satisfying this condition, it is possible to ensure that there are no rainbow fringes while ensuring a small difference in focal planes.

[0087] In some exemplary embodiments, the bottom surface of the microlens 10 is rectangular, and the length and width of each microlens 10 are between 16 μm and 22 μm.

[0088] In some exemplary embodiments, an absolute value ΔH of a difference between maximum heights of any two microlenses in the microlens array is ≤ 5 μm.

[0089] refer to Figure 7As shown, the diffuser provided in the above embodiment of the present application improves the imaging clarity by periodically arranging the microlenses and regularly configuring the microlens curvature radius, and at the same time uses the different height differences between any microlenses to achieve the purpose of suppressing the diffraction phenomenon. Therefore, it can ensure that the diffuser suppresses the diffraction phenomenon and also achieve a higher imaging clarity. Figure 7 and Figure 3 It can be seen from the comparison that the granularity of the diffuser provided by the present application is significantly reduced and the imaging clarity is significantly improved, thus having a better imaging effect. Embodiment 1

[0090] Figure 8 A schematic top view of a microlens of a diffusion plate according to the first embodiment of the present application is shown.

[0091] like Figure 8 As shown, the size of the diffusion plate of this embodiment is 100mm*40mm, and the diffusion angle is 22°*12°. The bottom surface of a single microlens is square, and the size (length and width) of the bottom surface of the microlens in the X direction and the Y direction are both 20μm.

[0092] like Fig. 9 As shown, by adding continuous random heights not exceeding 5 μm to the microlenses in the first region of the diffuser plate, the microlenses in the first region have different maximum heights. Fig. 9 The horizontal axis in represents the position on the diffuser plate, and each grid of the horizontal axis is 20 μm. The diffraction effect of the first area is as follows: Fig.10 shown.

[0093] The surface shape difference of adjacent microlenses on the horizontal section line is as follows Fig.11 As shown, the maximum difference is 11%. Fig.11 In the figure, the horizontal axis represents the bottom length / width of the microlens, and the vertical axis represents the surface difference between adjacent microlenses.

[0094] According to the diffusion plate of the first embodiment, the ratio of the height difference ΔH (unit: μm) between any microlenses to the length / width L of the microlenses is shown in Table 1 below.

[0095] Table 1

[0096]

[0097] According to the diffuser plate of the first embodiment of the present application, the ratio of the magnification difference to the height difference of adjacent microlenses is about 0.2. Fig.12 As shown, the diffuser plate of the first embodiment of the present application has a good anti-diffraction effect and a high imaging clarity. Embodiment 2

[0098] Fig.13A schematic top view of a microlens of a diffusion plate according to the second embodiment of the present application is shown.

[0099] like Fig.13 As shown, the size of the diffusion plate in this embodiment is 105mm*50mm, and the diffusion angle is 25°*8°. The bottom surface of a single microlens is square, and the size of the bottom surface of the microlens in the X direction and the Y direction is 20μm.

[0100] like Fig.14 As shown, by adding continuous random heights not exceeding 5 μm to the microlenses in the second region of the diffuser plate, the microlenses in the second region have different maximum heights. Fig.14 The horizontal axis in represents the position on the diffuser plate, and each grid of the horizontal axis is 20 μm. The diffraction effect of the second area is as follows: Fig.15 shown.

[0101] The surface shape difference of adjacent microlenses on the horizontal section line is as follows Fig.16 As shown, the maximum difference is 3%. Fig.16 In the figure, the horizontal axis represents the bottom length / width of the microlens, and the vertical axis represents the surface difference between adjacent microlenses.

[0102] According to the diffusion plate of the second embodiment, the ratio of the height difference ΔH (unit: μm) between any microlenses to the length / width L of the microlenses is shown in Table 2 below.

[0103] Table 2

[0104]

[0105] According to the diffuser plate of the second embodiment of the present application, the ratio of the magnification difference to the height difference of adjacent microlenses is about 0.5. Fig.17 As shown, the diffuser plate of the second embodiment of the present application has a good anti-diffraction effect and a high imaging clarity.

[0106] The diffuser of this embodiment is a deflection diffuser, that is, there is a deflection angle between the incident principal light and the outgoing principal light. Fig.18 As shown, the main incident light ray has a deflection angle of about 3° in the horizontal direction. Embodiment 3

[0107] According to one or more embodiments of the present application, a method 200 for manufacturing a diffuser plate is also provided. Fig.19 As shown, the manufacturing method 200 of the diffuser plate may include:

[0108] S210, providing a substrate, wherein the substrate has a first surface.

[0109] S220 , continuously arranging a plurality of micro lenses along a first direction and a second direction of a first surface on the substrate to form a micro lens array.

[0110] The first direction is perpendicular to the second direction; each microlens includes a bottom surface facing the first surface and a curved surface opposite to the bottom surface.

[0111] In some exemplary embodiments, the method 200 may further include: respectively setting different maximum heights for the plurality of microlenses in the microlens array, where the maximum height is the distance from the vertex to the bottom surface of the curved surface of each microlens. For example, a continuous random height may be added to the microlenses so that the plurality of microlenses have different maximum heights.

[0112] In some exemplary embodiments, the method 200 may further include: respectively setting different maximum heights for a plurality of microlenses in the microlens array, and making any two adjacent microlenses in the microlens array satisfy the following condition: 3 / 20≤ΔH / L≤1 / 4, wherein ΔH is the absolute value of the difference between the maximum heights of the two adjacent microlenses, and L is the maximum length or maximum width of any microlens in the two adjacent microlenses.

[0113] In some exemplary embodiments, the surface shape difference between any two adjacent microlenses in the microlens array satisfies at least one of the following conditions: the surface shape difference between any two adjacent microlenses is greater than zero and not greater than 15%; the projection of the position at which the maximum value of the surface shape difference between any two adjacent microlenses is located within the ±10% area of ​​the bottom center of any one of the microlenses; the surface shape difference at the corresponding position in the boundary area of ​​any two adjacent microlenses is greater than zero and not greater than 2%.

[0114] In some exemplary embodiments, each microlens has the same radius of curvature in the first direction and the same radius of curvature in the second direction.

[0115] In addition, the shape, height and curved surface design of each microlens in the microlens array of the diffuser plate have been described in detail in the exemplary implementations of the first and second embodiments above. For details, please refer to the aforementioned embodiments and will not be repeated here.

[0116] In addition, according to one or more embodiments of the present application, a projection system is also provided, which may include a light source and a diffuser according to any of the above embodiments, wherein the light beam emitted by the light source can form a uniform light field intensity after being diffused by the diffuser. The light incident surface of the diffuser is provided with a plurality of micro lenses, and when applied to a vehicle-mounted head-up display system, projection light is emitted according to the image to be projected, so that the projection light forms a real image of the image on the light incident surface of the diffuser; and then the diffuser expands the incident projection light to obtain expanded light, and emits the expanded light to the imaging surface.

[0117] In some exemplary embodiments, the projection system may include a HUD system. Further, the projection system may be an AR-HUD system, etc.

[0118] 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 replaced with the technical features with similar functions disclosed in this application (but not limited to) by each other to form a technical solution.

Claims

1. A diffuser plate, characterized in that: include: a substrate having a first surface; as well as A microlens array, disposed on the substrate, the microlens array comprising a plurality of microlenses continuously arranged along a first direction and a second direction of the first surface, wherein the first direction is perpendicular to the second direction; Wherein, each of the microlenses comprises a bottom surface facing the first surface, and a curved surface opposite to the bottom surface; The maximum heights of the plurality of microlenses in the microlens array are different, and any two adjacent microlenses in the microlens array satisfy the following condition: 3 / 20≤ΔH / L≤1 / 4, wherein ΔH is the absolute value of the difference between the maximum heights of the two adjacent microlenses, L is the maximum length or maximum width of any microlens of the two adjacent microlenses, and the maximum height is the distance from the vertex to the bottom surface of the curved surface of each microlens; Wherein, by adding continuous random heights to the microlenses of the diffusion plate, the plurality of microlenses in the microlens array have different maximum heights; In the microlens array, the surface shape difference between any two adjacent microlenses is greater than zero and not greater than 15%, wherein the surface shape difference refers to the ratio of the absolute value of the difference between the surface shape derivatives of the two adjacent microlenses to the surface shape derivative of any one of the microlenses.

2. The diffuser plate according to claim 1, wherein: The bottom surfaces of the microlenses in the microlens array have the same shape and size, the bottom surfaces centers of any adjacent microlenses in the first direction are aligned along the first direction, and the bottom surfaces centers of any adjacent microlenses in the second direction are aligned along the second direction.

3. The diffuser plate according to claim 2, wherein: The bottom surface of each microlens in the microlens array is rectangular.

4. The diffuser plate according to claim 1, wherein: In the microlens array, the projection of the position where the maximum value of the surface shape difference between any two adjacent microlenses is located is located within the ±10% area of ​​the bottom center of any microlens.

5. The diffuser plate according to claim 1, wherein: In the microlens array, the surface shape difference at corresponding positions in the boundary area of ​​any two adjacent microlenses is greater than zero and not greater than 2%, wherein the boundary area refers to the area outside the central area of ​​the microlens, and the distance from the projection position of any point in the central area to the center of the bottom surface of the microlens does not exceed 20% of the maximum length or maximum width of the bottom surface.

6. The diffuser plate according to claim 1, wherein: In the microlens array, each of the microlenses has the same radius of curvature in the first direction and the same radius of curvature in the second direction.

7. The diffuser plate according to claim 1, wherein: In the microlens array, any two adjacent microlenses satisfy the following conditions: ΔM / ΔH≤1, Wherein, ΔM is the absolute value of the difference between the magnifications of the two adjacent microlenses.

8. The diffuser plate according to claim 3, wherein: The length and width of each microlens are between 16 μm and 22 μm.

9. The diffuser plate according to any one of claims 1 to 8, wherein: In the microlens array, an absolute value ΔH of a difference in maximum heights between any two microlenses is ≤5 μm.

10. The diffuser plate according to any one of claims 1 to 8, wherein: The curved surface of each microlens in the microlens array is a convex surface.

11. A method for manufacturing a diffusion plate, characterized in that: The method comprises: Provide a substrate having a first surface; and A plurality of microlenses are continuously arranged on the substrate along a first direction and a second direction of the first surface to form a microlens array, wherein the first direction is perpendicular to the second direction; Each of the microlenses comprises a bottom surface facing the first surface, and a curved surface opposite to the bottom surface; The method further comprises: Different maximum heights are set for the plurality of microlenses in the microlens array, and any two adjacent microlenses in the microlens array satisfy the following conditions: 3 / 20≤ΔH / L≤1 / 4, Wherein, ΔH is the absolute value of the difference between the maximum heights of the two adjacent microlenses, L is the maximum length or maximum width of any microlens of the two adjacent microlenses, and the maximum height is the distance from the vertex to the bottom surface of the curved surface of each microlens; Wherein, respectively setting different maximum heights for the plurality of microlenses in the microlens array comprises: adding continuous random heights to the microlenses so that the plurality of microlenses in the microlens array have different maximum heights; In the microlens array, the surface shape difference between any two adjacent microlenses is greater than zero and not greater than 15%, wherein the surface shape difference refers to the ratio of the absolute value of the difference between the surface shape derivatives of the two adjacent microlenses to the surface shape derivative of any one of the microlenses.

12. A projection system, characterized in that: It comprises a light source and the diffusion plate according to any one of claims 1 to 10, wherein the light beam emitted by the light source forms a uniform light field intensity after being diffused by the diffusion plate.

13. The projection system according to claim 12, characterized in that: The projection system includes a heads-up display system.

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