Light diffuser, image source device and projection device

Abstract

The embodiment of the utility model provides a light diffuser, an image source device and a projection device, the light diffuser comprises an optical substrate and a microlens array arranged on the optical substrate, the microlens array comprises a plurality of microlenses, and at least two microlenses in the plurality of microlenses have different structural parameters. The structure parameters comprise at least one of the aperture, the focal length, the focal ratio and the included angle between the optical axis and the center line of the micro lens, the focal ratio is the ratio of the aperture of the micro lens to the focal length of the micro lens, and the different structure parameters change randomly. According to the image source, uniform light spot output without interference fringes is realized, and the light uniformizing effect is improved.

Description

Technical Field

[0001] The present disclosure relates to the technical field of optical display equipment, and in particular to a light diffuser, an image source device and a projection device. Background Art

[0002] There are various types of display devices. Take the head up display (HUD) as an example. The head up display projects the light emitted by the image source onto the imaging window, and uses the imaging window to reflect the light to the human eye to form an image, so that the user can directly see the picture without lowering his head, thereby improving the user experience. The head up display is mainly composed of an image source device and a reflective imaging window, wherein the image source device includes a light diffuser to homogenize the light. The light diffuser in the prior art usually adopts a periodic microlens array, which can meet the advantages of high diffraction efficiency, small size, and integration, but interference fringes will appear when the light beam is homogenized, affecting the homogenization effect of the output light spot. Utility Model Content

[0003] The purpose of the embodiments of the present disclosure is to provide a light diffuser, an image source device and a projection device, which achieve a better light uniformity effect.

[0004] In order to solve the above technical problems, the embodiments of the present disclosure adopt the following technical solutions: a light diffuser is provided, comprising an optical substrate and a microlens array arranged on the optical substrate, wherein the microlens array comprises a plurality of microlenses, and at least two of the plurality of microlenses have different structural parameters, wherein the structural parameters include at least one of the microlens aperture, focal length, focal ratio and angle between the optical axis and the center line, wherein the focal ratio is the ratio of the aperture of the microlens to the focal length of the microlens, and different structural parameters vary randomly.

[0005] In an exemplary embodiment, the random variation range of the aperture of the microlens is greater than or equal to -30um and less than or equal to 30um; and / or the variation of the aperture of the microlens relative to the basic aperture of the microlens is greater than or equal to -30% and less than or equal to 30%.

[0006] In an exemplary embodiment, the random variation range of the aperture of the microlens in the first direction and the second direction is greater than or equal to -30um and less than or equal to 30um; and / or the variation of the aperture of the microlens in the first direction and the second direction relative to the basic aperture of the microlens is greater than or equal to -30% and less than or equal to 30%, and the first direction is set at an angle to the second direction.

[0007] In an exemplary embodiment, at least two microlenses among the plurality of microlenses have different apertures and the apertures of the microlenses vary randomly, and the random variation of the apertures of the microlenses satisfies a linear relationship.

[0008] In an exemplary embodiment, at least two microlenses among the plurality of microlenses have different apertures and the apertures of the microlenses vary randomly, the focal ratios of the microlenses are the same and a fixed value, and the angles between the optical axes of the microlenses and the center line are 0°.

[0009] In an exemplary embodiment, at least two of the plurality of microlenses have different focal lengths and the focal lengths of the microlenses vary randomly, the apertures of the microlenses are the same and are a fixed value, and the angles between the optical axes of the microlenses and the center line are all 0°; or, at least two of the plurality of microlenses have different focal ratios and the focal ratios vary randomly, the apertures of the microlenses are the same and are a fixed value, and the angles between the optical axes of the microlenses and the center line are all 0°.

[0010] In an exemplary embodiment, at least two microlenses among the plurality of microlenses have different focal lengths and the focal lengths of the microlenses vary randomly, and the focal length variation range of the microlenses satisfies: ±30%.

[0011] In an exemplary embodiment, at least two micro-lenses among the plurality of micro-lenses have different focal ratios and the focal ratios vary randomly, and the variation of the focal ratios satisfies: ±30%.

[0012] In an exemplary embodiment, at least two microlenses among the plurality of microlenses have different angles between their optical axes and the center line and the angles vary randomly, and the aperture, focal length and focal ratio of each microlens are the same and fixed.

[0013] In an exemplary embodiment, the angle between the optical axis of the microlens and the center line varies in a range of greater than or equal to 1° and less than or equal to 10°.

[0014] In an exemplary embodiment, each microlens is rectangular in shape; and / or each microlens is one of a convex lens, a concave lens, or a combination of a convex lens and a concave lens.

[0015] In an exemplary embodiment, the plurality of microlenses in the microlens array include one or more of a non-spaced arrangement and a spaced arrangement, and the spacing between two adjacent microlenses in the plurality of spaced arrangement microlenses is less than or equal to 10 micrometers.

[0016] The disclosed embodiment further provides an image source device, including a backlight unit, an LCD screen and the above-mentioned light diffuser, wherein the light diffuser is located between the LCD screen and the backlight unit.

[0017] In an exemplary embodiment, there are one or more light diffusers. When there are multiple light diffusers, the multiple light diffusers include a first diffuser and a second diffuser. The first diffuser is located on a side of the second diffuser away from the LCD screen, and the diffusion angle of the first diffuser is greater than the diffusion angle of the second diffuser.

[0018] In an exemplary embodiment, the second diffuser is used to receive the light spot output by the first diffuser, and the distance between the second diffuser and the first diffuser satisfies that the second diffuser receives the light spot output by the first diffuser with a brightness uniformity greater than 80%.

[0019] In one exemplary embodiment, the aperture of the micro-lenses near the light diffuser of the LCD panel is smaller than the size of each pixel in the LCD panel.

[0020] The embodiment of the present disclosure further provides a projection device, comprising a projection unit and the above-mentioned light diffuser, wherein the light diffuser is located at the light emitting side of the projection unit.

[0021] In an exemplary embodiment, the aperture of the micro-lens of the light diffuser is smaller than the size of each pixel of the projection image emitted by the projection unit.

[0022] The light diffuser, image source device and projection device provided by the embodiments of the present disclosure have different structural parameters of at least two microlenses among the multiple microlenses, and the structural parameters include at least one of the microlens aperture, focal length, focal ratio and the angle between the optical axis and the center line, and the different structural parameters vary randomly. In this way, the light diffuser of the present application can homogenize the incident light beam, avoid the interference fringes and uneven brightness problems existing in the periodic light diffuser, and help to increase the homogenization effect of the light diffuser. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0024] Figure 1 is a schematic diagram of the arrangement of a micro-lens array of a light diffuser according to an embodiment of the present disclosure;

[0025] Figure 2 A schematic diagram of a structure in which the aperture of a microlens in an embodiment of the present disclosure changes randomly;

[0026] Figure 3 A schematic diagram of a structure in which the focal length or focal ratio of a microlens in an embodiment of the present disclosure varies randomly;

[0027] Figure 4 is a schematic diagram of a microlens according to an embodiment of the present disclosure when the angle between the optical axis and the center line is θ;

[0028] Figure 5A schematic diagram of a structure in which the angle between the optical axis and the center line of the micro-lens of the embodiment of the present disclosure changes randomly;

[0029] Figure 6 A structural arrangement diagram of an image source device according to an embodiment of the present disclosure is shown;

[0030] Figure 7 A structural arrangement diagram of an image source device according to another embodiment of the present disclosure is shown;

[0031] Figure 8 A diagram showing the structural arrangement relationship of a projection device according to an embodiment of the present disclosure is shown;

[0032] Fig. 9 A schematic diagram of a microlens according to an embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0033] Various aspects and features of the present disclosure are described herein with reference to the drawings.

[0034] It should be understood that various modifications may be made to the embodiments of the present application. Therefore, the above description should not be considered as limiting, but only as an example of an embodiment. Other modifications within the scope and spirit of the present disclosure will occur to those skilled in the art.

[0035] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the present disclosure and, together with the general description of the present disclosure given above and the detailed description of the embodiments given below, serve to explain the principles of the present disclosure.

[0036] These and other characteristics of the present disclosure will become apparent from the following description of a preferred form of embodiment given as a non-limiting example, with reference to the attached drawings.

[0037] It should also be understood that, although the present disclosure has been described with reference to some specific examples, those skilled in the art will be able to realize many other equivalent forms of the present disclosure that have the features described in the claims and are therefore within the scope of protection defined thereby.

[0038] The above and other aspects, features and advantages of the present disclosure will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

[0039] Specific embodiments of the present disclosure are described hereinafter with reference to the accompanying drawings; however, it should be understood that the embodiments claimed are merely examples of the present disclosure, which may be implemented in a variety of ways. Well-known and / or repeated functions and structures are not described in detail to avoid obscuring the present disclosure with unnecessary or redundant details. Therefore, the specific structural and functional details claimed herein are not intended to be limiting, but merely serve as a basis and representative basis for the claims to teach those skilled in the art to use the present disclosure in a variety of ways with substantially any suitable detailed structure.

[0040] This specification may use the phrases "in one embodiment," "in another embodiment," "in a further embodiment," or "in other embodiments," all of which may refer to one or more of the same or different embodiments according to the present disclosure.

[0041] According to one aspect of the present disclosure, a light diffuser is provided, including an optical substrate and a microlens array 10 arranged on the optical substrate, the microlens array 10 including a plurality of microlenses 11, at least two of the plurality of microlenses 11 having different structural parameters, the structural parameters including at least one of a microlens aperture, a focal length, a focal ratio, and an angle between an optical axis and a center line 12, wherein the focal ratio is a ratio of an aperture of the microlens 11 to a focal length of the microlens 11, and different structural parameters vary randomly.

[0042] It should be noted here that one or more parameters of the aperture, focal length, focal ratio and angle between the optical axis and the center line 12 of the two microlenses 11 can be set to be different and the different parameters can be randomly changed. When one of the aperture, focal length, focal ratio and angle between the optical axis and the center line 12 of the two microlenses 11 is set to be different and randomly changed, the angle between the optical axis and the center line 12 of the microlens can be selected to be different and randomly changed. Since the aperture, focal length and focal ratio of the microlens are interrelated, when the aperture of the microlens is set to change randomly, if one of the focal length and focal ratio is a fixed value, the other will change with the random change of the aperture; similarly, when the focal length of the microlens is set to change randomly, if one of the aperture and focal ratio is a fixed value, the other will change with the random change of the aperture.

[0043] When the multiple parameters of the aperture, focal length, focal ratio and angle between the optical axis and the center line 12 of the two microlenses 11 are different and vary randomly, the multiple parameters can be any two, any three or all of the microlens aperture, focal length, focal ratio and angle between the optical axis and the center line 12 that vary randomly. By setting the structural parameters of at least two of the multiple microlenses 11 of the light diffuser to be different and vary randomly, the microlens array of the light diffuser is a random microlens array, thereby achieving a better uniform light effect. The structural parameters of the microlens 11 include at least one of the aperture, focal length, focal ratio and angle between the optical axis and the center line 12 of the microlens 11. This avoids the problem of interference fringes existing in the periodic microlens array, which is beneficial to increase the uniformity effect of the light diffuser.

[0044] In an optional embodiment of the present application, the projection shape of each microlens 11 on the optical substrate is a rectangle, so that the light spot formed by the light passing through the light diffuser is a rectangular light spot. When the light diffuser is applied to a head-up display, the shape of the light spot homogenized by the light diffuser is better matched with the shape of the eye box of the head-up display, which is conducive to reducing the light propagating outside the eye box, thereby reducing energy waste. Of course, according to the different light spot shapes required, the projection shape of the microlens 11 can be selected as needed, such as circular, elliptical, hexagonal, octagonal, etc., without limitation.

[0045] The multiple microlenses 11 of the microlens array 10 may have structural parameters of some microlenses 11 that vary randomly, while structural parameters of other microlenses 11 do not vary; or structural parameters of all microlenses 11 vary randomly. The structural parameters include at least one of the aperture, focal length, focal ratio, and angle between the optical axis and the center line 12 of the microlens 11, which may be set according to actual conditions.

[0046] It should be noted that the random variation of the structural parameters of the above-mentioned part of the microlenses 11 includes that the structural parameters of only two microlenses 11 are different and the different structural parameters vary randomly, and the different structural parameters may be one or more of the aperture, focal length, focal ratio, and the angle between the optical axis and the center line 12 of the microlens 11. For example, when the microlens array 10 is composed of 100 microlenses 11, only two microlenses 11 among the 100 microlenses 11 may be set to have one or more of the aperture, focal length, focal ratio, and the angle between the optical axis and the center line 12 to be different, and the different structural parameters vary randomly.

[0047] In some examples, each microlens 11 in the microlens array 10 is one of a convex lens, a concave lens, or a combination of a convex lens and a concave lens. Specifically, the plurality of microlenses 11 in the microlens array 10 may all be convex lenses, or all be concave lenses, or all be a combination of convex lenses and concave lenses. In this case, one microlens 11 is composed of one convex lens and one concave lens.

[0048] In one example, the multiple microlenses 11 in the microlens array 10 can be arranged without spacing (also called densely packed arrangement), or can be arranged with spacing (also called non-densely packed arrangement), or some of the multiple microlenses 11 can be arranged without spacing, and the other part can be arranged with spacing. Among them, the spacing between two adjacent microlenses 11 in the multiple microlenses 11 arranged with spacing is less than or equal to 10 microns. By rationally planning the spacing size of the microlenses 11 arranged with spacing, it is helpful to ensure that the microlenses 11 can uniformly control the light beam, so as to obtain a light spot with controllable size and shape.

[0049] The light diffuser of the present disclosure is described below in conjunction with specific embodiments.

[0050] Reference Figure 1 and Figure 2 , showing a schematic diagram of a microlens array with randomly varying apertures. In one embodiment of the present disclosure, reference Figure 2 As shown in , at least two of the multiple microlenses 11 have different apertures and the apertures of the microlenses 11 vary randomly. The aperture of the microlens 11 is specifically the size of the projection shape of the microlens 11 on the optical substrate. When the projection shape of the microlens 11 on the optical substrate is a rectangle, the aperture is the side length of the rectangle; when the projection shape of the microlens 11 on the optical substrate is a circle, the aperture is the diameter of the circle; when the projection shape of the microlens 11 on the optical substrate is an ellipse, the aperture is the length of the major axis or minor axis of the ellipse; when the projection shape of the microlens 11 on the optical substrate is a hexagonal or octagonal polygon, the aperture is the diagonal length of the polygon. The aperture of the microlens 11 is not the cross-sectional area of ​​the microlens 11.

[0051] The random variation of the aperture of the microlens 11 satisfies a linear relationship, which is:

[0052] ±D*p / M;

[0053] Among them, ±D is the change in the aperture of the microlens 11; p is the basic aperture of the microlens 11; M is the size of the sub-region to which the microlens 11 belongs. It should be explained here that the multiple microlenses 11 of the present application are obtained by dividing the target area from the first level to the Nth level from large to small based on the size of the optical substrate. Therefore, M is the size of the sub-region to which the lens belongs during the division, and the size of the sub-region is actually the area size of the sub-region. 1<M<N.

[0054] For example, if Figure 2As shown in the figure, when the area with a bold black frame is the sub-area to which the microlens 11 belongs, the aperture variation ±D of the microlens 11, the basic aperture p of the microlens 11 and the area M of the sub-area satisfy a linear relationship: ±D*p / M. The aperture variation ±D of the microlens 11 includes the random variation of the aperture of the microlens 11 relative to the basic aperture in the x-axis direction and the random variation of the aperture of the microlens 11 relative to the basic aperture in the y-axis direction. Such a setting is conducive to ensuring that the aperture variation ±D of the microlens 11, the basic aperture p of the microlens 11 and the size M of the sub-area to which the microlens 11 belongs are in a proportional relationship, so as to ensure that the aperture variation ±D is within a reasonable range and to ensure the division process and stability.

[0055] In some embodiments of the present application, the apertures of the microlenses 11 in the microlens array 10 of a light diffuser vary randomly, and the focal ratios of the microlenses 11 are the same and a fixed value (the focal ratio can be expressed as tanα, and the relationship between the focal ratio and the divergence angle is: β1 2 +β2 2 =α 2 , where β1 is the divergence angle of the microlens in the x-axis direction, and β2 is the divergence angle of the microlens in the y-axis direction), the angle between the optical axis of each microlens 11 and the center line 12 is 0°. Since the focal ratio of the microlens 11 is the ratio of the aperture to the focal length, when the aperture of the microlens 11 changes randomly and the focal ratio is fixed, the focal length of the microlens 11 changes with the aperture of the microlens 11, thereby forming a randomly changing microlens array 10 to achieve the purpose of eliminating interference fringes. Figure 4 In the equation, tanα = aperture D of the microlens / focal length f of the microlens.

[0056] like Fig. 9 , which is a schematic diagram of a microlens 11, wherein β1 is the divergence angle of the microlens in the x-axis direction, β2 is the divergence angle of the microlens in the y-axis direction, and f is the focal length of the microlens. 2 +β2 2 =α 2. In the present embodiment, the random variation range of the aperture of the microlens 11 is greater than or equal to -30um (micrometer) and less than or equal to 30um (micrometer). Specifically, the random variation range of the aperture of the microlens 11 in the first direction (one of the aforementioned x-axis direction and y-axis direction) and the second direction (the other of the aforementioned x-axis direction and y-axis direction) is greater than or equal to -30um and less than or equal to 30um, and the first direction is perpendicular to the second direction, the first direction may be the x-axis direction, and the second direction may be the y-axis direction. In other words, the size of the microlens 11 in the first direction varies randomly, and the difference in the size of any two microlenses 11 in the first direction is less than or equal to 60um. The size of the microlens 11 in the second direction is similar, so it will not be repeated. By reasonably constraining the random variation range of the aperture of the microlens 11, it is beneficial to ensure that the aperture of the microlens 11 varies randomly within a controllable range, and control the light diffuser to finally form a spot size and shape to meet the requirements.

[0057] In the present embodiment, the random change of the aperture of the microlens 11 may be a random change based on the basic aperture of the microlens 11. The specific value of the basic aperture of the microlens 11 may be set according to actual conditions and is not limited here. Specifically, the change in the aperture of the microlens 11 relative to the basic aperture of the microlens 11 is greater than or equal to -30% and less than or equal to 30%. For example, the change in the aperture of the microlens 11 relative to the basic aperture of the microlens 11 in the first direction and the second direction is greater than or equal to -30% and less than or equal to 30%. The first direction may be the x-axis direction, and the second direction may be the y-axis direction. For example: if the basic aperture of the microlens 11 is 100 microns, the random change range of the aperture of the microlens 11 in the first direction and the second direction is greater than or equal to -30 microns and less than or equal to 30 microns.

[0058] Figure 1 An implementation method in which the aperture of the microlens 11 in this embodiment changes randomly is shown. The length of the basic aperture of the microlens 11 is 78.6562 microns and the width is 31.25 microns. The random fluctuation range of the aperture of the microlens 11 in the length direction and the width direction is ±25% of the length and width of the basic aperture, thereby obtaining a random microlens array 10. The projection shape of the microlens array 10 on the optical substrate is a rectangle with a length of 128 mm and a width of 64 mm. The length direction of the rectangle is the y-axis and the width direction is the x-axis. The diffusion angle of the microlens array 10 in the x-axis direction is 7.25° and the diffusion angle in the y-axis direction is 18.25°.

[0059] In another embodiment of the present disclosure, in addition to forming a random microlens array by randomly changing the aperture of the microlens 11, a random microlens array can also be formed by randomly changing the focal length or the focal ratio. Figure 3 As shown in Figure 3 , a schematic diagram of the structure of a microlens 11 is shown in which at least two of the multiple microlenses 11 have different focal lengths and the focal lengths of the microlenses 11 vary randomly, or at least two of the multiple microlenses 11 have different focal ratios and the focal ratios vary randomly. Figure 3 In the embodiment, when the focal lengths of at least two microlenses 11 among the plurality of microlenses 11 are different and the focal lengths of the microlenses 11 vary randomly, or when the focal ratios of at least two microlenses 11 among the plurality of microlenses 11 are different and the focal ratios vary randomly, the apertures of the microlenses 11 are the same and are constant. Therefore, the apertures of the microlenses 11 are the same. That is, Figure 3 In the figure, the projection shape of each microlens 11 on the optical substrate is a rectangle with the same size.

[0060] In some embodiments of the present invention, the focal length or focal ratio of each microlens 11 varies randomly. In this case, the aperture of each microlens 11 is the same and a fixed value. For example, the size of the aperture in the first direction is the basic aperture p. x The size of the aperture in the second direction is the base aperture p y , the angle between the optical axis of each microlens 11 and the center line 12 is 0°. When the focal length of each microlens 11 changes randomly, since the aperture of each microlens 11 is the same and constant, the focal ratio of each microlens 11 changes with the change of the focal length, thereby forming a randomly changing microlens array 10.

[0061] When the focal lengths of at least two of the plurality of microlenses 11 are different and the focal lengths of the microlenses 11 vary randomly, the focal length variation range of the microlenses 11 satisfies: ±30%. It should be explained here that the focal length variation range of the microlens 11 varies randomly within the range of ±30% of the basic focal length of the microlens 11, and the basic focal length of the microlens 11 can be selected according to actual conditions and is not limited here. For example, the basic focal length is determined based on the calculated basic aperture and divergence angle.

[0062] When the focal ratios of at least two of the plurality of microlenses 11 are different and vary randomly, the variation of the focal ratio satisfies: ±30%. It should be explained here that the variation of the focal ratio of the microlens 11 varies randomly within the range of ±30% of the basic focal ratio of the microlens 11, and the basic focal ratio of the microlens 11 can be set according to actual conditions and is not limited here. The basic focal ratio is determined according to the divergence angle of the light diffuser, and the relationship thereof satisfies the aforementioned relationship.

[0063] In another embodiment of the present disclosure, the angles between the optical axes of at least two microlenses 11 and the center line 12 of the plurality of microlenses 11 are different, and the angles between the optical axes of the microlenses 11 and the center line 12 vary randomly, where the center line 12 refers to the center line 12 of the microlens 11, and the center line 12 of the microlens 11 is arranged perpendicular to the optical substrate. In this case, the apertures of the microlenses 11 can be configured to be the same and a fixed value, the focal lengths of the microlenses 11 can be the same and a fixed value, and the focal ratios of the microlenses 11 can be the same and a fixed value.

[0064] For example, the range of the angle between the optical axis of the microlens 11 and the center line 12 is greater than or equal to 1° and less than or equal to 10°. By reasonably limiting the range of the angle between the optical axis of the microlens 11 and the center line 12, it is helpful to adjust the eccentricity of the microlens 11, thereby forming microlenses 11 with different divergent directions, which is helpful to eliminate interference fringes. Figure 5 FIG. 2 is a schematic diagram showing a randomly changing angle between the optical axis of the microlens 11 and the center line 12 in an optional embodiment of the present application. The figure shows two microlenses 11, both of which are eccentric lenses, that is, there is an angle between the optical axis of the two microlenses 11 and the center line 12, and the angle varies in the range of 1° to 10°.

[0065] like Figure 4 As shown, it is a light path diagram when the angle between the optical axis of the microlens 11 and the center line 12 is θ. Wherein, the aperture of the microlens 11 is D, the focal length f of the microlens 11, the eccentric distance d of the microlens 11 and the angle between the optical axis of the microlens 11 and the center line 12 is θ, which satisfies:

[0066] θ = arctan(d / f).

[0067] Optionally, the plurality of microlenses 11 in the microlens array 10 may be closely arranged without spacing. Alternatively, some of the microlenses 11 may be closely arranged without spacing, while the other part may be arranged at intervals. In this case, the focal length between two adjacent microlenses 11 in the other part of the microlenses 11 arranged at intervals is less than or equal to 10 micrometers. The close arrangement of the plurality of microlenses 11 ensures the uniformity of the light spot presented in the end.

[0068] The disclosed embodiment further provides an image source device, which includes a backlight unit 30, an LCD screen 40 and the above-mentioned light diffuser, wherein the light diffuser is located between the LCD screen 40 and the backlight unit 30. The light diffuser is used to homogenize and shape the light spot, so that the light spot output by the LCD screen 40 has good uniformity and the shape of the light spot is rectangular or quasi-rectangular.

[0069] The image source device further includes a collimating lens 50 and a reflector. The collimating lens 50 is located between the backlight unit 30 and the light diffuser to collimate the light of the backlight unit 30. The reflector includes at least a first reflector 61 and a second reflector 62. The second reflector 62 is located between the first reflector 61 and a windshield 70. The windshield 70 is located between the second reflector 62 and the human eye 80.

[0070] Specifically, the backlight unit 30 includes one or more lamp beads or one or more lamp tubes, which can be configured according to actual conditions.

[0071] exist Figure 6 In the image source device of an embodiment shown, there is one light diffuser 21, which is used to diffuse the light of the backlight unit 30 so as to output a uniform rectangular light spot, and the aperture of the microlens 11 of the light diffuser 21 is smaller than the size of each pixel of the LCD screen 40, thereby avoiding the risk of affecting the resolution due to the excessive size of the microlens 11.

[0072] exist Figure 7 In the image source device of another embodiment shown, there are multiple light diffusers, including a first diffuser 22 and a second diffuser 23. The first diffuser 22 is located on a side of the second diffuser 23 away from the LCD screen 40, and the diffusion angle of the first diffuser 22 is greater than the diffusion angle of the second diffuser 23. This arrangement allows the first diffuser 22 to perform preliminary diffusion of light, and the second diffuser 23 to receive the light emitted by the first diffuser 22 and further homogenize and diffuse the light.

[0073] Specifically, the second diffuser 23 is used to receive the light spot output by the first diffuser 22, and the distance between the second diffuser 23 and the first diffuser 22 satisfies that the second diffuser 23 receives the light spot output by the first diffuser 22 with a brightness uniformity greater than 80%. In other words, the second diffuser 23 needs to be placed at a plane position where the uniformity of the light spot emitted by the first diffuser 22 is greater than 80%, and the uniformity of the light spot can be derived from the following formula: The uniformity of the light spot is defined as 1-σ / C, where σ is the standard deviation of the light spot intensity and C is the average value of the light spot intensity.

[0074] In this embodiment, the aperture of the microlens 11 of the light diffuser close to the LCD screen 40 is smaller than the size of each pixel in the LCD screen 40, that is, the aperture of the microlens 11 of the second diffuser 23 is smaller than the size of each pixel in the LCD screen 40, thereby avoiding the risk of the microlens 11 being too large to affect the resolution.

[0075] The present disclosure also provides a projection device, such as Figure 8As shown, the projection device includes a projection unit 90 and the above-mentioned light diffuser 21. The light diffuser 21 is located on the light-emitting side of the projection unit 90. The light diffuser 21 is used to diffuse and expand the projection light emitted by the projection light source and form it into image light.

[0076] Specifically, the projection unit 90 can be a DLP projection unit or an LCOS projection unit, and can be set according to actual conditions. The projection device also includes a reflector and a windshield 70, which are arranged in sequence in a direction away from the light diffuser 21 and are located between the light diffuser 21 and the human eye 80. The reflector includes at least a first reflector 61 and a second reflector 62, and the second reflector 62 is located between the first reflector 61 and the windshield 70.

[0077] In this embodiment, the aperture of the microlens 11 of the light diffuser 21 is smaller than the size of each pixel of the projection image emitted by the projection unit 90 , thereby ensuring the resolution of the final projection image and the clarity of the projection image.

[0078] The above description is only a preferred embodiment of the present disclosure and an explanation of the technical principles used. Those skilled in the art should understand that the scope of disclosure involved in the present disclosure is not limited to the technical solutions 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 above disclosed concept. For example, the above features are replaced with the technical features with similar functions disclosed in the present disclosure (but not limited to) by each other to form a technical solution.

[0079] In addition, although each operation is described in a specific order, this should not be understood as requiring these operations to be performed in the specific order shown or in a sequential order. Under certain circumstances, multitasking and parallel processing may be advantageous. Similarly, although some specific implementation details are included in the above discussion, these should not be interpreted as limiting the scope of the present disclosure. Some features described in the context of a separate embodiment can also be implemented in a single embodiment in combination. On the contrary, the various features described in the context of a single embodiment can also be implemented in multiple embodiments individually or in any suitable sub-combination mode.

Claims

1. A light diffuser, characterized in that: The invention comprises an optical substrate and a microlens array arranged on the optical substrate, wherein the microlens array comprises a plurality of microlenses, and at least two of the plurality of microlenses have different structural parameters, wherein the structural parameters comprise at least one of the microlens aperture, focal length, focal ratio and angle between the optical axis and the center line, wherein the focal ratio is the ratio of the aperture of the microlens to the focal length of the microlens, and different structural parameters vary randomly.

2. The light diffuser according to claim 1, characterized in that The random variation range of the aperture of the microlens is greater than or equal to -30um and less than or equal to 30um; and / or The change in the aperture of the microlens relative to the basic aperture of the microlens is greater than or equal to -30% and less than or equal to 30%.

3. The light diffuser according to claim 1, characterized in that The random variation range of the aperture of the microlens in the first direction and the second direction is greater than or equal to -30um and less than or equal to 30um; and / or The variation of the aperture of the microlens relative to the basic aperture of the microlens in the first direction and the second direction is greater than or equal to -30% and less than or equal to 30%, and the first direction is set at an angle to the second direction.

4. The light diffuser according to any one of claims 1 to 3, characterized in that: At least two of the plurality of microlenses have different apertures and the apertures of the microlenses vary randomly, and the random variation of the apertures of the microlenses satisfies a linear relationship.

5. The light diffuser according to any one of claims 1 to 3, characterized in that: At least two of the plurality of microlenses have different apertures and the apertures of the microlenses vary randomly, the focal ratios of the microlenses are the same and are a fixed value, and the angles between the optical axes of the microlenses and the center line are all 0°.

6. The light diffuser according to any one of claims 1 to 3, characterized in that: The focal lengths of at least two of the plurality of microlenses are different and vary randomly, the apertures of the microlenses are the same and are a fixed value, and the angles between the optical axes of the microlenses and the center line are 0°; Alternatively, at least two of the plurality of microlenses have different focal ratios and the focal ratios vary randomly, the apertures of the microlenses are the same and are a fixed value, and the angles between the optical axes of the microlenses and the center line are all 0°.

7. The light diffuser according to claim 6, characterized in that At least two of the plurality of microlenses have different focal lengths and the focal lengths of the microlenses vary randomly. The focal length variation range of the microlens meets: ±30%.

8. The light diffuser according to claim 6, characterized in that At least two of the plurality of microlenses have different focal ratios and the focal ratios vary randomly. The variation of the focal ratio satisfies: ±30%.

9. The light diffuser according to claim 1, characterized in that The included angles between the optical axes and the center line of at least two of the plurality of microlenses are different and the included angles between the optical axes and the center line vary randomly. The aperture, focal length and focal ratio of each microlens are the same and fixed.

10. The light diffuser according to claim 9, characterized in that The range of the included angle between the optical axis of the microlens and the center line is greater than or equal to 1° and less than or equal to 10°.

11. The light diffuser according to claim 1, characterized in that The shape of each of the micro lenses is rectangular; and / or each of the micro lenses is one of a convex lens, a concave lens, or a combination of a convex lens and a concave lens.

12. The light diffuser according to claim 1, characterized in that The plurality of microlenses in the microlens array include one or more of a non-spaced arrangement and a spaced arrangement, and a spacing between two adjacent microlenses in the plurality of spaced microlenses is less than or equal to 10 micrometers.

13. An image source device, characterized in that: The invention comprises a backlight unit, an LCD screen and the light diffuser according to any one of claims 1 to 12, wherein the light diffuser is located between the LCD screen and the backlight unit.

14. The image source device according to claim 13, characterized in that: There are one or more light diffusers. When there are multiple light diffusers, the multiple light diffusers include a first diffuser and a second diffuser. The first diffuser is located on a side of the second diffuser away from the LCD screen, and a diffusion angle of the first diffuser is greater than a diffusion angle of the second diffuser.

15. The image source device according to claim 14, characterized in that: The second diffuser is used to receive the light spot output by the first diffuser, and the distance between the second diffuser and the first diffuser satisfies that the second diffuser receives the light spot output by the first diffuser with a brightness uniformity greater than 80%.

16. The image source device according to claim 13 or 14, characterized in that: The aperture of the micro-lens of the light diffuser close to the LCD screen is smaller than the size of each pixel in the LCD screen.

17. A projection device, characterized in that: The invention comprises a projection unit and the light diffuser according to any one of claims 1 to 12, wherein the light diffuser is located at a light emitting side of the projection unit.

18. The projection device according to claim 17, characterized in that: The aperture of the micro lens of the light diffuser is smaller than the size of each pixel of the projection image emitted by the projection unit.

Images