Light guide plate, backlight module and display device

Abstract

The application provides a light guide plate, a backlight module and a display device, and relates to the technical field of light guide plates. The light guide plate comprises an incident light surface, a bottom surface and an exit light surface. The incident light surface is used for receiving light emitted by a light source and guiding the light into the light guide plate. The bottom surface is provided with a plurality of optical microstructures. The optical microstructures are used for reflecting and / or refracting the light in the light guide plate to the exit light surface for emission. The optical microstructures comprise a first light surface. In a first direction, the first tangent slope of the first surface type of the first light surface changes according to a second preset rule. In a second direction, the second tangent slope of the first surface type of the first light surface changes according to a third preset rule. The first direction is perpendicular to the incident light surface. The second direction is parallel to the bottom surface and perpendicular to the first direction. Through the design of the first tangent slope and the second tangent slope of the first surface type of the first light surface, the application can inhibit the occurrence of dispersion and hot spot phenomena.

Description

Light guide plate, backlight module and display device Technical Field

[0001] This application relates to the technical field of light guide plates, and more specifically, to a light guide plate, a backlight module, and a display device. Background Technology

[0002] In liquid crystal display (LCD) devices, the backlight module is a key component that provides uniform brightness and a stable surface light source. The light guide plate is the core component of the backlight module. It directs the light emitted by point light sources (such as LED beads) located on the side through total internal reflection within the light guide plate. By breaking the total internal reflection condition through microstructures set on its bottom or surface, the light is uniformly guided out from the light-emitting surface, thereby converting the point light source into a surface light source.

[0003] To ensure the uniformity and brightness of light emitted from the surface light source, traditional backlight modules typically have multiple layers of optical thin films (such as diffusion films and brightness enhancement films) sequentially placed on the light-emitting side of the light guide plate. However, the inventors of this application have discovered that the multi-layer optical thin film structure results in a high cost for the backlight module.

[0004] The content in the background section is merely technology known to the public and does not necessarily represent existing technology in this field. Summary of the Invention

[0005] This application provides a light guide plate, a backlight module, and a display device, aiming to solve the technical problems of rainbow pattern and hot spot phenomena in the current backlight module structure where the light guide plate is directly placed below the liquid crystal module.

[0006] According to one aspect of this application, a light guide plate is provided. The light guide plate includes an incident surface, a bottom surface, and an exiting surface. The incident surface is used to receive light emitted from a light source assembly and guide the light into the interior of the light guide plate. A plurality of optical microstructures are disposed on the bottom surface, which are used to reflect and / or refract light from inside the light guide plate to exit through the exiting surface. The optical microstructures include a first light surface, wherein the slope of a first surface tangent of the first light surface varies according to a second preset rule along a first direction, and the slope of a second surface tangent of the first light surface varies according to a third preset rule along a second direction. The first direction is perpendicular to the incident surface, and the second direction is parallel to the bottom surface and perpendicular to the first direction.

[0007] According to some embodiments of this application, the absolute value of the first surface tangent slope of the first optical surface corresponds to the first surface tangent slope curve, which is a first curve function. The first surface tangent slope curve shows an upward trend. Along the first direction, from the vertex of the optical microstructure to the bottom point of the first optical surface, the absolute value of the first surface tangent slope of the first optical surface shows an overall increasing trend. And / or the absolute value of the second surface tangent slope of the first optical surface corresponds to the second surface tangent slope curve, which is a second curve function. The second surface tangent slope curve shows an upward trend. Along the second direction, on one side of the center of the optical microstructure, from the center of the optical microstructure to the boundary point of the first optical surface, the absolute value of the second surface tangent slope of the first optical surface shows an overall increasing trend.

[0008] According to some embodiments of this application, the slope curve of the first surface tangent is monotonically increasing; and / or, the slope curve of the second surface tangent is monotonically increasing.

[0009] According to some embodiments of this application, the rate of change of the slope of the first facet tangent away from the bottom surface is greater than the rate of change of the slope of the first facet tangent near the bottom surface; and / or the rate of change of the slope of the second facet tangent away from the bottom surface is greater than the rate of change of the slope of the second facet tangent near the bottom surface.

[0010] According to some embodiments of this application, the optical microstructure further includes: a second optical surface connected to the first optical surface, wherein the surface shape of the second optical surface is curved or planar.

[0011] According to some embodiments of this application, the slope of the first surface tangent is in the range of 0 < |B| ≤ 3, where |B| is the absolute value of the slope of the first surface tangent; and / or the slope of the second surface tangent is in the range of 0 < |C| ≤ 1.5, where |C| is the absolute value of the slope of the second surface tangent.

[0012] According to some embodiments of this application, the range of values ​​for the radius of curvature corresponding to the slope curve of the first surface type tangent is as follows:

[0013] ; and / or

[0014] The range of values ​​for the radius of curvature corresponding to the slope curve of the tangent line of the second surface is:

[0015] .

[0016] in, Let be the radius of curvature corresponding to the slope curve of the tangent line of the first surface type. The radius of curvature is the curve of the tangent slope of the second surface, and K is the conic coefficient of the aspherical surface.

[0017] According to some embodiments of this application, the thickness of the light guide plate ranges as follows:

[0018] Where d is the thickness of the light guide plate.

[0019] According to some embodiments of this application, the aspect ratio P / W of the first glossy surface ranges from 0.5 to 0.9; where P is the length of the first glossy surface and W is the width of the first glossy surface.

[0020] According to some embodiments of this application, the aspect ratio H / W of the first glossy surface ranges from 0.25 to 0.72; where H is the depth of the first glossy surface and W is the width of the first glossy surface.

[0021] According to some embodiments of this application, the length of the optical microstructure is ≤10µm, the width of the optical microstructure is ≤10µm; and / or the length of the first optical surface is ≤10µm, the width of the first optical surface is ≤10µm.

[0022] According to some embodiments of this application, a preset bottom angle is provided between the first smooth surface and the bottom surface, and the value of the preset bottom angle is in the range of 20° to 60°.

[0023] According to some embodiments of this application, the optical microstructure is recessed inward on the bottom surface, with the first light surface close to the light-incident surface and the second light surface far from the light-incident surface. The first light surface is a curved surface convex towards the light-out surface and the second light surface is a curved surface convex towards the light-incident surface. Alternatively, the optical microstructure is protruding outward on the bottom surface, with the first light surface far from the light-incident surface and the second light surface close to the light-incident surface. The first light surface is a curved surface convex away from the light-out surface and the second light surface is a curved surface convex away from the light-incident surface.

[0024] According to another aspect of this application, a backlight module is also provided. The backlight module includes a light guide plate as described above. The backlight module also includes a light source assembly comprising a plurality of sub-light sources spaced apart along a second direction, the sub-light sources emitting light.

[0025] According to another aspect of this application, a display device is also provided. The display device includes a light guide plate as described above, and further includes a liquid crystal module, with at most one optical film layer disposed between the light guide plate and the liquid crystal module. Alternatively, the display device includes a backlight module as described above.

[0026] Beneficial effects

[0027] This application provides a light guide plate, which includes an incident surface, a bottom surface, and an exiting surface. The incident surface receives light emitted from a light source and guides the light into the interior of the light guide plate. The bottom surface has multiple optical microstructures that reflect and / or refract light from inside the light guide plate to exit through the exiting surface. The optical microstructures include a first light surface; along a first direction, the slope of the tangent of a first surface shape of the first light surface varies according to a second preset rule; and along a second direction, the slope of the tangent of a second surface shape of the first light surface varies according to a third preset rule.

[0028] This application designs the tangent slope of the first surface of the first optical surface so that the tangent slope of the first surface is different at each point in the first direction. This allows light to be scattered on the first optical surface, suppressing dispersion and thus preventing the formation of rainbow patterns. Furthermore, this application designs the tangent slope of the second surface of the first optical surface so that the tangent slope of the second surface is different at each point in the second direction. This also allows light to be scattered on the first optical surface, altering the brightness and darkness areas between sub-light sources and suppressing the formation of hot spots. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 shows a schematic diagram of the structure of a backlight module in the prior art;

[0031] Figure 2 shows a schematic diagram of the structure of another backlight module in the prior art;

[0032] Figure 3 shows a schematic diagram of a dispersion phenomenon;

[0033] Figure 4 shows a schematic diagram of a rainbow pattern phenomenon;

[0034] Figure 5 shows a schematic diagram of the light distribution in the prior art;

[0035] Figure 6 shows a schematic diagram of a hotspot phenomenon;

[0036] Figure 7 shows a schematic diagram of the structure of the light guide plate according to an embodiment of this application;

[0037] Figure 8a shows a schematic diagram of the distribution of optical microstructures according to an embodiment of this application;

[0038] Figure 8b shows another schematic diagram of the distribution of the optical microstructure in an embodiment of this application;

[0039] Figure 8c shows another schematic diagram of the distribution of the optical microstructure in an embodiment of this application;

[0040] Figure 9 shows a three-dimensional schematic diagram of the optical microstructure of an embodiment of this application;

[0041] Figure 10a shows a schematic diagram of the ZX cross-section of an optical microstructure according to an embodiment of this application;

[0042] Figure 10b shows a schematic diagram of the ZY cross-section of the optical microstructure according to an embodiment of this application;

[0043] Figure 10c shows a schematic diagram of the XY cross-section of an optical microstructure according to an embodiment of this application;

[0044] Figure 11 shows a schematic diagram of the light emission angle of an embodiment of this application;

[0045] Figure 12a shows a schematic diagram of an optical microstructure according to an embodiment of this application;

[0046] Figure 12b shows another schematic diagram of the optical microstructure of an embodiment of this application;

[0047] Figure 12c shows another structural schematic diagram of the optical microstructure according to an embodiment of this application;

[0048] Figure 13 shows a schematic diagram of the slope of the tangent line of the first surface shape according to an embodiment of this application;

[0049] Figure 14 shows a schematic diagram of the scattering of the first light surface in an embodiment of this application;

[0050] Figure 15 shows a schematic diagram of the slope of the second surface tangent in an embodiment of this application;

[0051] Figure 16 shows a schematic diagram of the scattering of the first light surface according to an embodiment of this application;

[0052] Figure 17a shows another schematic diagram of the slope of the surface tangent in an embodiment of this application;

[0053] Figure 17b shows another schematic diagram of the slope of the surface tangent in an embodiment of this application;

[0054] Figure 18 shows a schematic diagram of the diffusion angle in an embodiment of this application;

[0055] Figure 19 shows another schematic diagram of the slope of the second facet tangent in an embodiment of this application;

[0056] Figure 20 shows another schematic diagram of the slope of the tangent line of the first surface shape according to an embodiment of this application;

[0057] Figure 21 is a schematic diagram of the effect of the light guide plate according to an embodiment of this application;

[0058] Figure 22 shows another schematic diagram of the slope of the second surface tangent in an embodiment of this application;

[0059] Figure 23 shows another schematic diagram of the slope of the tangent line of the first surface shape according to an embodiment of this application;

[0060] Figure 24 shows another schematic diagram of the slope of the second surface tangent in an embodiment of this application;

[0061] Figure 25 shows another schematic diagram of the slope of the tangent line of the first surface shape according to an embodiment of this application;

[0062] Figure 26 shows another schematic diagram of the slope of the second surface tangent in an embodiment of this application;

[0063] Figure 27 shows another schematic diagram of the slope of the tangent line of the first surface shape according to an embodiment of this application;

[0064] Figure 28 shows another schematic diagram of the slope of the second surface tangent in an embodiment of this application;

[0065] Figure 29 shows another schematic diagram of the slope of the tangent line of the first surface shape according to an embodiment of this application;

[0066] Figure 30a shows a schematic diagram of the location of an optical microstructure according to an example embodiment of this application;

[0067] Figure 30b shows another locational schematic diagram of the optical microstructure of an example embodiment of this application.

[0068] Explanation of reference numerals in the attached figures:

[0069] Light source assembly 10; light guide plate 20; sub-light source 11; light incident surface S1; bottom surface S2; light emitting surface S3; optical microstructure 21; first light surface 211; second light surface 212. Detailed Implementation

[0070] The technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0071] Figure 1 shows a schematic diagram of the structure of a prior art backlight module; Figure 2 shows a schematic diagram of the structure of another prior art backlight module; Figure 3 shows a schematic diagram of a dispersion phenomenon; Figure 4 shows a schematic diagram of a rainbow pattern phenomenon; Figure 5 shows a schematic diagram of the light distribution in the prior art; Figure 6 shows a schematic diagram of a hot spot phenomenon.

[0072] As shown in Figure 1, the multilayer optical film of this backlight module includes: two diffusion films (such as an upper diffusion film and a lower diffusion film with haze) and two brightness enhancement films (such as prism films). The diffusion films can use internal light scattering particles (haze) to diffuse the light emitted from the light guide plate a second time, thereby eliminating the problem of uneven light and achieving uniform light output. The brightness enhancement films, through their prism structure, converge large-angle light to the front viewing angle, which can effectively improve the brightness of the emitted light from the front.

[0073] However, the inventors of this application have discovered that backlight modules with multi-layer optical thin film structures have two main drawbacks. First, the high cost of the optical thin films themselves leads to a higher overall cost for the backlight module. Second, the multi-layer stacked structure also increases the assembly complexity and overall thickness of the backlight module.

[0074] As shown in Figure 2, this backlight module removes all optical films (such as diffusion films and brightness enhancement films) and places the light guide plate directly below the liquid crystal module.

[0075] However, the inventors of this application have also discovered that backlight modules with this structure have at least the following problems:

[0076] 1. Rainbow pattern phenomenon:

[0077] Light guide plates are typically made of polymer materials such as polycarbonate and polymethyl methacrylate, which themselves exhibit significant dispersion effects (i.e., the refractive index varies with the wavelength of light). As shown in Figure 3, due to the dispersion of the light guide plate substrate, when light is incident and scattered at a specific angle, light of different wavelengths separates due to different angles of refraction (as shown by the different colors of light in Figure 3). When light of different wavelengths is incident on the surface of the microstructure, because the tangent slope of the microstructure's surface facing the light is the same, the reflected light corresponding to different wavelengths continues to disperse. Ultimately, these dispersed light rays are refracted at the interface between the light guide plate and the air, producing a rainbow effect (as shown in Figure 4). This dispersion phenomenon is more pronounced in the area of ​​the light guide plate near the light source (near-light area). The rainbow effect degrades the color purity and visual appeal of the displayed image, thus affecting the display effect of the liquid crystal display device.

[0078] 2. Hot Spot Phenomenon:

[0079] As shown in Figure 5, due to the physical spacing between the LED beads, when light enters from the side of the light guide plate, the light from different LED beads in the area near the light source (near light source area) has not yet fully mixed. This light overlap results in periodic brightness variations, known as hotspot phenomena (as shown in Figure 6). Liquid crystal display devices equipped with light guide plates exhibiting this phenomenon will display uneven brightness, severely impacting the display quality.

[0080] According to one aspect of this application, a light guide plate is provided. Figure 7 shows a schematic structural diagram of a light guide plate according to an embodiment of this application.

[0081] According to an example embodiment, the light source assembly 10 includes a plurality of spaced sub-light sources 11, which emit light L.

[0082] For example, as shown in Figure 7, the light source assembly 10 may include a plurality of spaced sub-light sources 11 (such as LED beads), and the sub-light sources 11 may emit uniform light L.

[0083] According to an example embodiment, the light guide plate 20 provided in this application includes an incident surface S1, a bottom surface S2, and an exiting surface S3. The incident surface S1 is used to receive the light L emitted by the light source assembly 10 and guide the light L into the interior of the light guide plate 20. The bottom surface S2 is provided with a plurality of optical microstructures 21, which are used to reflect and / or refract the light L inside the light guide plate 20 to exit through the exiting surface S3.

[0084] For example, as shown in Figure 7, in the XYZ coordinate system, the incident surface S1 is positioned opposite to the light source assembly 10, receiving the light L from the light source assembly 10. The bottom surface S2 is positioned perpendicular to the incident surface S1, and the emitting surface S3 is positioned parallel to the bottom surface S2. The optical microstructure 21 on the bottom surface S2 can disrupt the total internal reflection condition of the light L in the light guide plate 20 and guide the light L to exit from the emitting surface S3, thereby ensuring uniform light emission from the emitting surface S3.

[0085] Optionally, the length of the optical microstructure 21 is ≤10 μm, and / or the width of the optical microstructure 21 is ≤10 μm. By controlling the size of individual optical microstructures, this application enables the light guide plate to have good transparency.

[0086] Figure 8a shows a schematic diagram of the distribution of the optical microstructure in an embodiment of this application; Figure 8b shows another schematic diagram of the distribution of the optical microstructure in an embodiment of this application; Figure 8c shows yet another schematic diagram of the distribution of the optical microstructure in an embodiment of this application.

[0087] Optionally, the optical microstructures 21 can be distributed on the bottom surface S2 based on a first preset rule. The first preset rule can be customized according to user needs. The first preset rule includes, but is not limited to, array arrangement rules, gradient density arrangement rules, and random arrangement rules.

[0088] For example, as shown in Figure 8a, the optical microstructures 21 are uniformly arranged on the bottom surface S2 according to an array arrangement rule. As shown in Figure 8b, the optical microstructures 21 are arranged on the bottom surface S2 according to a gradient density arrangement rule, such that the arrangement density of the optical microstructures 21 in the region closer to the light source component 10 is greater than the arrangement density of the optical microstructures 21 in the region farther away from the light source component 10. As shown in Figure 8c, the optical microstructures 21 are randomly arranged on the bottom surface S2 according to a random arrangement rule.

[0089] Figure 9 shows a three-dimensional schematic diagram of the optical microstructure of an embodiment of this application; Figure 10a shows a schematic diagram of the ZX cross section of the optical microstructure of an embodiment of this application; Figure 10b shows a schematic diagram of the ZY cross section of the optical microstructure of an embodiment of this application; Figure 10c shows a schematic diagram of the XY cross section of the optical microstructure of an embodiment of this application; Figure 12a shows a schematic diagram of one structure of the optical microstructure of an embodiment of this application; Figure 12b shows another schematic diagram of one structure of the optical microstructure of an embodiment of this application; Figure 12c shows yet another schematic diagram of one structure of the optical microstructure of an embodiment of this application.

[0090] According to an example embodiment, the optical microstructure 21 includes a first optical surface 211.

[0091] For example, as shown in Figure 9, in the XYZ coordinate system, the optical microstructure 21 includes a first optical surface 211. The first optical surface 211 can be a light-facing surface, that is, the first optical surface 211 faces the incident direction of the light ray L. The surface shape of the first optical surface 211 can be a curved surface, and the bottom edge of the first optical surface 211 is arc-shaped, which bulges out in the incident direction of the light ray L.

[0092] Optionally, the optical microstructure 21 further includes a second optical surface 212. The second optical surface 212 is connected to the first optical surface 211.

[0093] For example, as shown in Figure 9, in the XYZ coordinate system, the first light surface 211 and the second light surface 212 are smoothly connected. The second light surface 212 can be a backlight surface, that is, the second light surface 212 faces away from the incident direction of the light ray L.

[0094] According to the example embodiment, as shown in Figure 10a, in the XYZ coordinate system, the ZX cross section of the optical microstructure 21 is triangular (or approximately triangular), and the first light surface 211 protrudes towards the incident direction of the light ray L. Furthermore, the first light surface 211 and the bottom surface S2 have a predetermined bottom angle. As shown in Figure 10b, in the XYZ coordinate system, the ZY section of the optical microstructure 21 is arc-shaped (or approximately arc-shaped), the width of the optical microstructure 21 (which is also the width of the first optical surface 211) is W, and the height of the optical microstructure 21 (which is also the height of the first optical surface 211) is H. As shown in Figure 10c, in the XYZ coordinate system, the XY section of the optical microstructure 21 is an irregular circle (the first optical surface 211 is a convex arc-shaped structure), and the horizontal length of the first optical surface 211 is P.

[0095] Optionally, the aspect ratio P / W of the first smooth surface 211 ranges from 0.5 to 0.9. And / or, the depth-to-width ratio H / W of the first smooth surface 211 ranges from 0.25 to 0.72.

[0096] This application, through the design of the aspect ratio of the first optical surface, allows the optical microstructure to be adjusted simultaneously in both the first and second directions, thus avoiding the generation of hot spots and rainbow patterns. Furthermore, through the design of the depth-to-width ratio of the first optical surface, this application allows the optical microstructure to have a flatter surface in the second direction, thereby enabling stronger light scattering and preventing the generation of hot spots.

[0097] Optionally, the length P of the first smooth surface 211 is ≤10um, and / or the width W of the first smooth surface 211 is ≤10um.

[0098] This application ensures uniform light output by controlling the size (length and / or width) of the first optical surface to below 10µm, making its critical dimensions lower than the characteristic period of common optical films.

[0099] Figure 11 shows a schematic diagram of the light emission angle of an embodiment of this application.

[0100] Optionally, preset bottom corner The value range is 20° to 60°.

[0101] For example, as shown in Figure 11, this setting allows the light angle to be obtained. Meets light emission requirements (e.g., 30°~60°).

[0102] Optionally, the surface of the second smooth surface 212 is either curved or flat.

[0103] For example, the surface shape of the second smooth surface 212 can be customized according to user needs.

[0104] For example, taking the ZX section of the optical microstructure 21 as an example, as shown in Figure 12a or 12b, the surface shape of the second optical surface 212 is curved. As shown in Figure 12c, the surface shape of the second optical surface 212 is planar.

[0105] Figure 13 shows a schematic diagram of the tangent slope of the first surface shape according to an embodiment of this application; Figure 14 shows a schematic diagram of the scattering of the first light surface according to an embodiment of this application; Figure 15 shows a schematic diagram of the tangent slope of the second surface shape according to an embodiment of this application; Figure 16 shows a schematic diagram of the scattering of the first light surface according to an embodiment of this application.

[0106] According to the example embodiment, along the first direction, the slope B of the first surface tangent of the first light surface 211 varies according to a second preset rule. And along the second direction, the slope C of the second surface tangent of the first light surface 211 varies according to a third preset rule. The first direction is perpendicular to the incident light surface S1, and the second direction is parallel to the bottom surface S2 and perpendicular to the first direction.

[0107] The slope of the tangent line is used to characterize the inclination of the tangent line at a point on the surface of the first optical surface 211. Different tangent line slopes result in different refraction angles of light rays at those points.

[0108] According to the example embodiment, along the first direction, the slope B of the first surface tangent of the first smooth surface 211 varies according to a second preset rule, so that the slope B of the first surface tangent at each point on the first smooth surface 211 along the first direction is different.

[0109] Optionally, at least 80% of the area of ​​the first smooth surface 211 has a first surface tangent slope B that varies according to a second preset rule, and at least 80% of the area of ​​the first smooth surface 211 has a second surface tangent slope C that varies according to a third preset rule.

[0110] For example, as shown in Figure 13, in the XYZ coordinate system, taking the ZX section as an example, the connection point between the first smooth surface 211 and the second smooth surface 212 is taken as point O, and the formula for the first surface curve of the first smooth surface 211 along the first direction is denoted as follows: Let ① be a reference point on the surface in the first direction. Then, the x-coordinate of reference point ① on the x-axis is X1, the radius of curvature is R1, and the surface tangent Z is: Where B is the slope of the first surface tangent at reference point ①.

[0111] As shown in Figure 13, along the first direction, the absolute values ​​of the slopes |B| of the first surface tangents at all reference points on the first smooth surface 211 constitute the first surface tangent slope curve. 0 ≤ x ≤ Xmax, Xmax = L. The slope curve of the tangent line to the first surface type. , for The derivative of .

[0112] As shown in Figure 14, the slopes B of the tangents on the first surface 211 are all different. For example, B1≠B2≠B3, B4≠B5≠B6, and B7≠B8≠B9. In the first direction, because the curvature of the first surface 211 is different at different positions and the slopes B of the tangents are also different, light rays L of the same wavelength (light rays L of the same color in Figure 14) will be scattered when incident on the surface of the optical microstructure 21. Therefore, as shown in Figure 14, when light rays L of different colors are incident on the surface of the optical microstructure 21 at the same time, scattering will occur. After scattering, the light rays L of different colors will mix, which can suppress the occurrence of dispersion. The mixed light rays refract out of the light guide plate, thereby avoiding the generation of rainbow patterns.

[0113] It can be understood that the greater the slope of the tangent of the optical microstructure, the greater the scattering of light, resulting in better light mixing and thus better suppression of rainbow effects. However, as the slope of the tangent changes, the light emission angle also changes. Therefore, it is necessary to adjust and control the slope of the tangent while ensuring the light emission angle.

[0114] According to the example embodiment, along the second direction, the slope of the second surface tangent of the first smooth surface 211 varies according to a third preset rule, so that the slope C of the second surface tangent of the first smooth surface 211 along the second direction is different.

[0115] For example, as shown in Figure 15, in the XYZ coordinate system, taking the ZY section as an example, the center of the optical microstructure 21 is taken as point O, and the formula for the second surface shape curve of the first optical surface 211 along the second direction is: Let ② be a reference point on the surface in the second direction. Then, the ordinate of reference point ② on the Y-axis is Y1, the radius of curvature is R2, and the surface tangent Z is: Where C is the slope of the second surface tangent at reference point ②.

[0116] As shown in Figure 15, along the second direction, the absolute values ​​of the second-plane tangent slopes C of all reference points on one side of the center of the optical microstructure 21, |C|, constitute the second-plane tangent slope curve. 0 ≤ y ≤ Ymax, Ymax = W / 2. The slope curve of the tangent line of the second surface type. , for The derivative of .

[0117] As shown in Figure 16, in the second direction (taking one side of the center of the optical microstructure 21 as an example), due to the different curvatures of the first optical surface 211 at different positions and the different slopes C of the tangent of the second surface, light rays L of the same wavelength will be scattered when incident on the surface of the optical microstructure 21. By scattering, the brightness and dark areas between the sub-light sources 11 can be changed, thereby suppressing the generation of hot spots.

[0118] Through the above embodiments, this application provides a light guide plate, which includes an incident surface, a bottom surface, and an exiting surface. The incident surface is used to receive light emitted from a light source and guide the light into the interior of the light guide plate. A plurality of optical microstructures are disposed on the bottom surface, which are used to reflect and / or refract light from inside the light guide plate to exit through the exiting surface. The optical microstructures include a first light surface, wherein the slope of the tangent of a first surface shape of the first light surface varies according to a second preset rule along a first direction, and the slope of the tangent of a second surface shape of the first light surface varies according to a third preset rule along a second direction.

[0119] This application designs the tangent slope of the first surface of the first optical surface so that the tangent slope of the first surface is different at each point in the first direction. This allows light to be scattered on the first optical surface, suppressing dispersion and thus preventing the formation of rainbow patterns. Furthermore, this application designs the tangent slope of the second surface of the first optical surface so that the tangent slope of the second surface is different at each point in the second direction. This also allows light to be scattered on the first optical surface, altering the brightness and darkness areas between sub-light sources and suppressing the formation of hot spots.

[0120] Optionally, the absolute value of the slope B of the first surface tangent of the first smooth surface 211 corresponds to the slope curve of the first surface tangent. The first curve function, the slope curve of the tangent line of the first surface type. The absolute value of the slope B of the first surface tangent of the first optical surface 211 increases along the first direction, from the vertex of the optical microstructure 21 (vertex P in Figure 9) to the bottom point of the first optical surface 211 (bottom point Q in Figure 9).

[0121] For example, as shown in Figure 13, the slope curve of the tangent line of the first surface type It shows an upward trend, that is, there exist 0, X2, and Xmax on the X-axis, such that . The slope of the tangent line at the top of the optical microstructure 21. The slope of the tangent line at the bottom of the optical microstructure 21.

[0122] For example, the first curve function includes, but is not limited to, quadratic functions, cubic functions, functions of higher quadratic degree, and square root functions.

[0123] Optionally, the absolute value of the second surface tangent slope C of the first smooth surface 211 corresponds to the second surface tangent slope curve. The second curve function, the slope curve of the tangent line of the second surface type. The absolute value of the slope C of the second surface tangent of the first optical surface 211 increases as a whole, along the second direction, on the side of the center of the optical microstructure 21 (center point M in Figure 9), from the center of the optical microstructure 21 to the boundary point of the first optical surface 211 (boundary point N in Figure 9).

[0124] For example, as shown in Figure 15, on one side of the center of the optical microstructure 21 (i.e., on the side of the origin O), the slope curve of the second surface tangent. It shows an upward trend, that is, there are 0, Y2, and Ymax on the Y-axis, such that . The slope of the tangent line at the top of the optical microstructure 21. The slope of the tangent line at the bottom of the optical microstructure 21.

[0125] For example, the second curve function includes, but is not limited to, quadratic functions, cubic functions, functions of higher quadratic degree, and square root functions.

[0126] Optionally, the slope curve of the tangent line of the first facet is monotonically increasing. The slope curve of the tangent line of the second facet is monotonically increasing.

[0127] Figure 17a shows another schematic diagram of the slope of the tangent line of the surface shape according to an embodiment of the present application; Figure 17b shows another schematic diagram of the slope of the tangent line of the surface shape according to an embodiment of the present application.

[0128] As shown in Figures 17a and 17b, the slope of the surface tangent can be monotonically increasing or fluctuating, but the overall trend of the surface tangent slope is increasing.

[0129] This application, through a design where the tangent slope of the first surface gradually increases, ensures that light of all wavelengths can be fully scattered on the first optical surface in the first direction, achieving sufficient light mixing and thus effectively suppressing rainbow patterns. Furthermore, this application, through a design where the tangent slope of the second surface gradually increases, ensures that light of all wavelengths can be fully scattered on the first optical surface in the second direction, thus further preventing the generation of hot spots.

[0130] Optionally, the rate of change of the slope B of the first facet tangent away from the bottom surface S2 is greater than the rate of change of the slope B of the first facet tangent closer to the bottom surface S2.

[0131] For example, as shown in Figure 13, the slope curve of the tangent line of the first surface type The rate of change of the slope B of the tangent line at the bottommost facet is greater than the slope curve of the tangent line of the first facet. The rate of change at the very top. That is, in At this point, the slope curve of the tangent line of the first surface type The rate of change is greater than The rate of change at that point.

[0132] With this configuration, in the first direction, the position on the first light surface away from the light source component has a stronger scattering ability for light, which can further effectively suppress the rainbow effect.

[0133] Optionally, the rate of change of the slope C of the second facet tangent away from the bottom surface S2 is greater than the rate of change of the slope C of the second facet tangent closer to the bottom surface S2.

[0134] For example, as shown in Figure 15, on one side of the center of the optical microstructure 21 (i.e., on the side of the origin O), the slope curve of the second surface tangent. The rate of change of the slope C of the second-side tangent at the bottom is greater than that of the second-side tangent slope curve. The rate of change at the very top. At that point, the slope curve of the tangent line of the second surface type rate of change, greater than The rate of change at that point.

[0135] With this configuration, in the second direction, the position on the first light surface away from the light source component has a stronger scattering ability for light, thereby further avoiding the generation of hot spots.

[0136] Optionally, the slope B of the first surface tangent is in the range of 0 < |B| ≤ 3, where |B| is the absolute value of the slope B of the first surface tangent.

[0137] For example, according to Fresnel's law, based on the relationship between the refraction and slope of light, it can be seen that when the value range of the slope B of the first surface tangent of the first light surface 211 satisfies 0 < |B| ≤ 3, the change in the exit angle of the light ray L can be controlled within ±5° under the premise of suppressing the rainbow effect, thereby meeting the light exit requirements.

[0138] Optionally, the slope C of the second facet tangent is in the range of 0 < |C| ≤ 1.5, where |C| is the absolute value of the slope C of the second facet tangent.

[0139] For example, the greater the slope of the surface tangent, the greater the scattering of light, resulting in better light mixing and thus better suppression of hotspots. However, as the slope of the surface tangent changes, greater scattering leads to a significant decrease in the brightness of the light guide plate.

[0140] According to Fresnel's law, based on the relationship between light refraction and slope, if the value of the slope C of the second surface tangent of the first light surface 211 satisfies 0 < |C| ≤ 1.5, the brightness reduction of the light guide plate can be controlled within 10% while suppressing hot spot phenomena.

[0141] Optionally, when the surface shape of the first smooth surface 211 is aspherical, the slope curve of the tangent line of the first surface shape is... The corresponding radius of curvature The range of values ​​for is:

[0142] ; and / or

[0143] The slope curve of the tangent line of the second surface The corresponding radius of curvature The range of values ​​for is:

[0144] ;

[0145] in, The slope curve of the tangent line of the first surface type The corresponding radius of curvature, The slope curve of the tangent line of the second surface type The corresponding radius of curvature, K is the conic coefficient of the aspherical surface.

[0146] For example, when the surface shape of the first optical surface 211 is aspherical, by designing the radius of curvature corresponding to the tangent slope curve of the first surface shape, and by controlling the surface shape of individual optical microstructures, the rainbow effect can be further effectively suppressed. Furthermore, by designing the radius of curvature corresponding to the tangent slope curve of the second surface shape, and by controlling the surface shape of individual optical microstructures, the generation of hotspots can be further avoided.

[0147] Figure 18 shows a schematic diagram of the diffusion angle of an embodiment of this application.

[0148] Optionally, when the surface shape of the first light surface 211 is aspherical, the thickness of the light guide plate 20 can be within the following range:

[0149] ;

[0150] Where d is the thickness of the light guide plate 20.

[0151] For example, since the uneven diffusion of light L is caused by the spacing between the sub-light sources, the hot spot phenomenon is related to the thickness of the light guide plate. As shown in Figure 18, the slope curve of the second surface tangent... The corresponding radius of curvature The size of the diffusion angle α is determined. Based on the diffusion angle α, the thickness d of the light guide plate 20, and the requirements for the tangent slopes of the first and second surfaces, the following can be calculated:

[0152] ;

[0153] ;

[0154] Therefore, according to the above formula, we can calculate: .

[0155] With this configuration, by designing the thickness of the light guide plate and controlling the surface shape of individual optical microstructures, this application can further avoid the generation of hot spots.

[0156] Figure 19 shows another schematic diagram of the second surface tangent slope of an embodiment of this application; Figure 20 shows another schematic diagram of the first surface tangent slope of an embodiment of this application; Figure 21 is a schematic diagram of the effect of the light guide plate of an embodiment of this application.

[0157] As an example, the length and width of the optical microstructure are 6*7µm. As shown in Figure 19, the maximum absolute value of the slope of the second surface tangent is 1.25. The slope curve of the second surface tangent is monotonically increasing, for example, a monotonically increasing parabola, with a continuous and smooth gradual change. The rate of increase of the slope gradually decreases, resulting in better uniformity of light efficiency in the light guide plate, natural brightness transition, and no abrupt differences. As shown in Figure 20, the maximum absolute value of the slope of the first surface tangent is 2.6. The slope curve of the first surface tangent is fluctuating upwards, with an overall upward trend. The aspect ratio of the first light surface is 0.6, the aspect ratio of the first light surface is 0.3, and the preset bottom angle is 30°. As shown in Figure 21, after the corresponding light guide plate is lit, no hot spot phenomenon or rainbow pattern phenomenon is generated.

[0158] Figure 22 shows another schematic diagram of the slope of the second facet tangent in an embodiment of this application; Figure 23 shows another schematic diagram of the slope of the first facet tangent in an embodiment of this application.

[0159] In another embodiment, the length and width of the optical microstructure are 5*9µm. As shown in Figure 22, the maximum absolute value of the slope of the second surface tangent is 1.5, and the slope curve of the second surface tangent shows a fluctuating upward trend with an overall upward trend. As shown in Figure 23, the maximum absolute value of the slope of the first surface tangent is 2.9, and the slope curve of the first surface tangent shows a fluctuating upward trend with an overall upward trend. The aspect ratio of the first optical surface is 0.85, the aspect ratio of the first optical surface is 0.7, and the preset bottom angle is 60°. After the corresponding light guide plate is lit, no hot spot phenomenon or rainbow pattern phenomenon is generated.

[0160] Figure 24 shows another schematic diagram of the slope of the second facet tangent in an embodiment of this application; Figure 25 shows another schematic diagram of the slope of the first facet tangent in an embodiment of this application.

[0161] In another embodiment, the length and width of the optical microstructure are 7*9µm. As shown in Figure 24, the maximum absolute value of the slope of the second surface tangent is 0.8, and the slope curve of the second surface tangent is monotonically increasing, for example, a monotonically increasing parabola. As shown in Figure 25, the maximum absolute value of the slope of the first surface tangent is 2, and the slope curve of the first surface tangent is monotonically increasing, for example, a monotonically increasing parabola. The aspect ratio of the first optical surface is 0.55, the aspect ratio of the first optical surface is 0.3, and the preset bottom angle is 40°. After the corresponding light guide plate is lit, no hot spot phenomenon or rainbow pattern phenomenon is generated.

[0162] Figure 26 shows another schematic diagram of the slope of the second facet tangent in an embodiment of this application; Figure 27 shows another schematic diagram of the slope of the first facet tangent in an embodiment of this application.

[0163] In another embodiment, the length and width of the optical microstructure are 5*7µm. As shown in Figure 26, the maximum absolute value of the slope of the second surface tangent is 0.4, and the slope curve of the second surface tangent is monotonically increasing, for example, a monotonically increasing parabola. As shown in Figure 27, the maximum absolute value of the slope of the first surface tangent is 1, and the slope curve of the first surface tangent is monotonically increasing, continuously and smoothly changing, with the rate of increase of the slope gradually decreasing. This results in better uniformity of light efficiency in the light guide plate, natural brightness transition, and no abrupt differences. The aspect ratio of the first light surface is 0.68, the aspect ratio of the first light surface is 0.49, and the preset bottom angle is 30°. After the corresponding light guide plate is lit, no hot spot phenomenon or rainbow pattern phenomenon is generated.

[0164] Figure 28 shows another schematic diagram of the slope of the second facet tangent in an embodiment of the present application; Figure 29 shows another schematic diagram of the slope of the first facet tangent in an embodiment of the present application.

[0165] In another embodiment, the length and width of the optical microstructure are 4*6µm. As shown in Figure 28, the maximum absolute value of the slope of the second surface tangent is 0.38, and the slope curve of the second surface tangent is monotonically increasing. As shown in Figure 29, the maximum absolute value of the slope of the first surface tangent is 0.6, the slope curve of the first surface tangent is monotonically increasing, the aspect ratio of the first optical surface is 0.72, the aspect ratio of the first optical surface is 0.26, and the preset bottom angle is 21°. After the corresponding light guide plate is lit, no hot spot phenomenon or rainbow pattern phenomenon is generated.

[0166] Figure 30a shows a positional schematic diagram of an optical microstructure according to an example embodiment of the present application; Figure 30b shows another positional schematic diagram of an optical microstructure according to an example embodiment of the present application.

[0167] Optionally, the optical microstructure 21 is recessed inward on the bottom surface S2, with the first light surface 211 close to the light-incident surface S1 and the second light surface 212 away from the light-incident surface S1. The first light surface 211 is a curved surface convex towards the light-outceasing surface S3 and the second light surface 212 is a curved surface convex towards the light-incident surface S1.

[0168] Alternatively, the optical microstructure 21 protrudes outward on the bottom surface S2, with the first light surface 211 away from the light-incident surface S1 and the second light surface 212 close to the light-incident surface S1. The first light surface 211 is a curved surface protruding away from the light-outceasing surface S3 and the first light surface 212 is a curved surface protruding away from the light-incident surface S1.

[0169] For example, as one embodiment, as shown in FIG30a, the optical microstructure 21 can be recessed inward on the bottom surface S2, and the light L is refracted out of the light guide plate 20 after being incident on the first light surface 211. As another embodiment, as shown in FIG30b, the optical microstructure 21 can be protruding outward on the bottom surface S2, and the light L is refracted out of the light guide plate 20 after being incident on the first light surface 211.

[0170] According to another aspect of this application, a backlight module is also provided, which includes a light guide plate as described above.

[0171] According to another aspect of this application, a display device is also provided, which includes a light guide plate or a backlight module as described above.

[0172] For example, the display device can be a liquid crystal display device.

[0173] Optionally, the display device may also include a liquid crystal module, with up to one optical film layer disposed between the light guide plate and the liquid crystal module. For example, the optical film layer may be a diffusion film.

[0174] For example, without an optical film layer, the light guide plate and the liquid crystal module can be directly stacked and installed, as shown in Figure 2.

[0175] Finally, it should be noted that the above description is merely a preferred embodiment of this application and is not intended to limit this application. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions of the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A light guide plate, characterized in that, The light guide plate includes an incident surface, a bottom surface, and an exiting surface. The incident surface is used to receive light emitted from the light source assembly and guide the light into the interior of the light guide plate. The bottom surface is provided with a plurality of optical microstructures, which are used to reflect and / or refract light from inside the light guide plate to exit through the exiting surface. The optical microstructure includes a first light surface, and along a first direction, the slope of the first surface tangent of the first light surface varies according to a second preset rule. Along the second direction, the slope of the second facet tangent of the first optical surface varies according to a third preset rule; wherein, the first direction is perpendicular to the incident light surface, and the second direction is parallel to the bottom surface and perpendicular to the first direction; the first facet tangent slope curve corresponding to the absolute value of the first facet tangent slope of the first optical surface is a first curve function, the first facet tangent slope curve shows an upward trend, and along the first direction, from the vertex of the optical microstructure to the bottom point of the first optical surface, the absolute value of the first facet tangent slope of the first optical surface shows an overall increasing trend; and / or the slope of the second facet tangent of the first optical surface... The second surface tangent slope curve corresponding to the absolute value of the rate is the second curve function. The second surface tangent slope curve shows an upward trend. Along the second direction, on one side of the center of the optical microstructure, from the center of the optical microstructure to the boundary point of the first optical surface, the absolute value of the second surface tangent slope of the first optical surface shows an overall increasing trend. The rate of change of the first surface tangent slope away from the bottom surface is greater than the rate of change of the first surface tangent slope close to the bottom surface. The rate of change of the second surface tangent slope away from the bottom surface is greater than the rate of change of the second surface tangent slope close to the bottom surface.

2. The light guide plate according to claim 1, characterized in that, The slope curve of the tangent line of the first surface type is monotonically increasing; and / or, the slope curve of the tangent line of the second surface type is monotonically increasing.

3. The light guide plate according to claim 1, characterized in that, The optical microstructure further includes a second optical surface connected to the first optical surface, wherein the surface of the second optical surface is curved or planar.

4. The light guide plate according to claim 1, characterized in that, The slope of the first surface tangent ranges from 0 to |B| ≤ 3, where |B| is the absolute value of the slope of the first surface tangent; and / or the slope of the second surface tangent ranges from 0 to |C| ≤ 1.5, where |C| is the absolute value of the slope of the second surface tangent.

5. The light guide plate according to claim 1, characterized in that, The range of values ​​for the radius of curvature corresponding to the slope curve of the first surface is: ; and / or the range of values ​​for the radius of curvature corresponding to the slope curve of the second surface type tangent is: ;in, The radius of curvature is the curve corresponding to the slope of the tangent line of the first surface shape. is the radius of curvature corresponding to the slope curve of the tangent line of the second surface type, and K is the conic coefficient of the aspherical surface.

6. The light guide plate according to claim 5, characterized in that, The thickness of the light guide plate ranges as follows: Where d is the thickness of the light guide plate.

7. The light guide plate according to claim 1, characterized in that, The aspect ratio P / W of the first smooth surface ranges from 0.5 to 0.9; where P is the length of the first smooth surface and W is the width of the first smooth surface.

8. The light guide plate according to claim 1, characterized in that, The aspect ratio H / W of the first light surface ranges from 0.25 to 0.72; where H is the depth of the first light surface and W is the width of the first light surface.

9. The light guide plate according to claim 1, characterized in that, The length of the optical microstructure is ≤10 μm, and the width of the optical microstructure is ≤10 μm; and / or the length of the first optical surface is ≤10 μm, and the width of the first optical surface is ≤10 μm.

10. The light guide plate according to claim 1, characterized in that, The first smooth surface and the bottom surface have a preset bottom angle, the value of which ranges from 20° to 60°.

11. The light guide plate according to claim 3, characterized in that, The optical microstructure is recessed inward on the bottom surface, with the first light surface close to the light-incident surface and the second light surface away from the light-incident surface. The first light surface is a curved surface convex towards the light-out surface and the second light surface is a curved surface convex towards the light-incident surface. Alternatively, the optical structure protrudes outward on the bottom surface, with the first light surface away from the light-incident surface and the second light surface close to the light-incident surface. The first light surface is a curved surface convex away from the light-out surface and the second light surface is a curved surface convex away from the light-incident surface.

12. A backlight module, characterized in that, Including the light guide plate as described in any one of claims 1-11, the backlight module further includes: a light source assembly comprising a plurality of sub-light sources spaced apart along the second direction, the sub-light sources emitting the light.

13. A display device, characterized in that, The display device includes a light guide plate as described in any one of claims 1-11; The display device further includes a liquid crystal module, wherein at most one optical film layer is disposed between the light guide plate and the liquid crystal module; Alternatively, the display device may include the backlight module as described in claim 12.

Images