Diffusion plate, backlight module and display device

Abstract

The application discloses a diffusion plate, a backlight module and a display device, wherein the diffusion plate comprises a substrate and a first diffusion structure layer, and the first diffusion structure layer is located on the surface of the substrate; the first diffusion structure layer comprises first protrusions and second protrusions, the pattern of the first protrusions divides the first diffusion structure layer into multiple sub-zones, the second protrusions are located in the sub-zones, and the height of the second protrusions is less than the height of the first protrusions; the first protrusions are used for refracting incident light into the substrate, converting large-angle light into smaller-angle light, and reducing the occurrence of total reflection, thereby improving the problem of light leakage to adjacent sub-zones; and the second protrusions are used for emitting at least part of the incident light out of the substrate after multiple reflections, and can homogenize the light.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of display, in particular to a diffusion plate, a backlight module and a display device. BACKGROUND

[0002] The direct backlight module adopts the Mini Light Emitting Diode (Mini LED or Micro Light Emitting Diode, Micro LED for short) backlight technology, arranges the Mini LED or Micro LED in an array as the backlight source of the Liquid Crystal Display (LCD), can divide the backlight module into independently controllable partitions, presents a brighter or darker picture through the Local Dimming technology, and improves the dynamic contrast of the liquid crystal display panel by the High Dynamic Range Imaging (HDR) technology, has the advantages of high contrast, high brightness, thin and light, etc.

[0003] However, in the backlight source, the light emitted by a certain partition may leak into the adjacent non-light-emitting partition, resulting in light leakage phenomenon, that is, Halo Effect, and further reducing the contrast of the display picture and affecting the quality of the display picture. SUMMARY

[0004] The present application provides a diffusion plate, a backlight module and a display device to prevent light leakage phenomenon between partitions of the backlight source and improve the contrast and brightness of the display picture.

[0005] In a first aspect, the present application provides a diffusion plate, comprising: a substrate and a first diffusion structure layer, the first diffusion structure layer is located on the surface of the substrate; the first diffusion structure layer comprises a first protrusion and a second protrusion, the height of the first protrusion is greater than the height of the second protrusion, the pattern of the first protrusion divides the first diffusion structure layer into a plurality of partitions, and the second protrusion is located in the partition; the first protrusion is used for refracting incident light to the inside of the substrate, and the second protrusion is used for reflecting at least part of the incident light multiple times and then emitting to the substrate.

[0006] In some embodiments of the present application, the first protrusions comprise a plurality of first protrusion portions; some of the first protrusion portions extend along a first direction, and a plurality of the first protrusion portions extending along the first direction are arranged along a second direction; other of the first protrusion portions extend along the second direction, and a plurality of the first protrusion portions extending along the second direction are arranged along the first direction, and the first direction and the second direction intersect.

[0007] In some embodiments of the present application, the second protrusions comprise a plurality of second protrusion portions; some of the second protrusion portions extend along a third direction in each of the sub-regions, and a plurality of the second protrusion portions extending along the third direction are arranged along a fourth direction; other of the second protrusion portions extend along the fourth direction, and a plurality of the second protrusion portions extending along the fourth direction are arranged along the third direction, and the third direction and the fourth direction intersect.

[0008] In some embodiments of the present application, at least some of the second protrusion portions arranged along the third direction are arranged in a spaced-apart manner or in a contacting manner; at least some of the second protrusion portions arranged along the fourth direction are arranged in a spaced-apart manner or in a contacting manner.

[0009] In some embodiments of the present application, in a direction perpendicular to the substrate and directed from the substrate to the first diffusion structure layer, the cross-sectional area of the first protrusion portion gradually decreases.

[0010] In some embodiments of the present application, the width and the height of the first protrusion portion satisfy the following relationship:

[0011] (R1) / 2≤h1≤R1

[0012] wherein R1 represents half of the width of the first protrusion portion, the width of the first protrusion portion being the width of the cross-section of the first protrusion portion in the extending direction; and h1 represents the height of the first protrusion portion.

[0013] In some embodiments of the present application, the width and the height of the second protrusion portion satisfy the following relationship:

[0014] (R2) / 2≤h2≤R2

[0015] wherein R2 represents half of the width of the second protrusion portion, the width of the second protrusion portion being the width of the cross-section of the second protrusion portion in the extending direction; and h2 represents the height of the second protrusion portion.

[0016] In some embodiments of the present application, the width of the first protrusion portion and the width of the second protrusion portion satisfy the following relationship:

[0017] 2R2≤R1≤3R2

[0018] wherein R1 represents half of the width of the first protruding part, the width of the first protruding part being half of the width of the cross section of the first protruding part in the extending direction; and R2 represents the width of the second protruding part, the width of the second protruding part being the width of the cross section of the second protruding part in the extending direction.

[0019] In some embodiments of the present application, the height of the first protruding part and the second protruding part satisfy the following relationship:

[0020] 2h2≤h1≤3h2

[0021] wherein h1 represents the height of the first protruding part; and h2 represents the height of the second protruding part.

[0022] In some embodiments of the present application, the diffusion plate further comprises a second diffusion structure layer, the second diffusion structure layer being located on the side of the substrate away from the first diffusion structure layer; the second diffusion structure layer comprises a plurality of recessed parts, the cross-sectional area of the recessed parts gradually increases in the direction perpendicular to the substrate and directed from the substrate to the second diffusion structure layer.

[0023] In some embodiments of the present application, the recessed part is a quadrangular pyramid, the apex angle of the quadrangular pyramid is greater than or equal to 30°, and the apex angle of the quadrangular pyramid is less than or equal to 80°.

[0024] In the second aspect, the present application provides a backlight module, comprising: a light source and any one of the diffusion plates of the first aspect, the first diffusion structure layer of the diffusion plate facing the light source; the light source comprising a plurality of light emitting elements, each of the light emitting elements corresponding to one or more sub-regions of the first diffusion structure layer; in the height direction of the second protrusion, the orthographic projection of the light emitting element is located at the center position of the orthographic projection of the corresponding one or more sub-regions.

[0025] In some embodiments of the present application, the distance between the light source and the diffusion plate satisfies the following relationship:

[0026] L1=2×(h1+H)×tanθ

[0027] wherein L1 represents the distance between adjacent light emitting elements; h1 represents the height of the first protrusion; H represents the distance between the light emitting element and the first diffusion structure layer; and θ represents half of the light emitting angle of the light emitting element.

[0028] In some embodiments of the present application, the backlight module comprises two diffusion plates, the two diffusion plates comprising a first diffusion plate and a second diffusion plate, the second diffusion plate being located on a side of the first diffusion plate away from the light source, a first diffusion structure layer of the first diffusion plate facing the light source, and a first diffusion structure layer of the second diffusion plate facing the first diffusion plate.

[0029] In a third aspect, the present application provides a display device, the display device comprising a display panel and any one of the backlight modules of the second aspect, the display panel being located on a light-out side of the backlight module.

[0030] The present application has the following advantages:

[0031] The present application provides a diffusion plate, a backlight module and a display device, wherein the diffusion plate comprises a substrate and a first diffusion structure layer, the first diffusion structure layer being located on a surface of the substrate; the first diffusion structure layer comprises first protrusions and second protrusions, the height of the first protrusions being greater than the height of the second protrusions, a pattern of the first protrusions dividing the first diffusion structure layer into a plurality of sub-zones, and the second protrusions being located in the sub-zones; the first protrusions are used for refracting incident light rays into the substrate, converting large-angle light rays into smaller-angle light rays, and reducing the occurrence of total reflection, thereby improving the problem of light leakage to adjacent sub-zones, and the second protrusions are used for emitting at least part of the incident light rays out of the substrate after multiple reflections, thereby homogenizing the light rays. BRIEF DESCRIPTION OF DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments of the present application will be briefly introduced below. Obviously, the drawings introduced below are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0033] Figure 1 The structural schematic diagram of the display device provided by the embodiments of the present application is shown in the figure.

[0034] Figure 2 The structural schematic diagram of the backlight module provided by the embodiments of the present application is shown in the figure.

[0035] Figure 3 The structural schematic diagram of the first diffusion structure layer in the diffusion plate provided by the embodiments of the present application is shown in the figure.

[0036] Figure 4 The cross-sectional schematic diagram of the diffusion plate and the light source provided by the embodiments of the present application is shown in the figure.

[0037] Figure 5 The structural schematic diagram of the second diffusion structure layer provided by the embodiments of the present application is shown in the figure.

[0038] Figure 6 Light intensity distribution diagram of a single light emitting element modulated by a conventional diffusion plate;

[0039] Figure 7 Light intensity distribution diagram of a single light emitting element modulated by a diffusion plate provided by an embodiment of the present application;

[0040] Figure 8 Comparison diagram of point spread function curves of a light emitting element modulated by a conventional diffusion plate and a diffusion plate provided by an embodiment of the present application;

[0041] Figure 9 Light intensity distribution diagram of a backlight module provided with a diffusion plate provided by an embodiment of the present application;

[0042] Figure 10 Light intensity distribution diagram of a light source modulated by a conventional diffusion plate;

[0043] Figure 11 Light intensity distribution diagram of a light source modulated by a diffusion plate provided by an embodiment of the present application;

[0044] Figure 12 Structure diagram of a first diffusion structure layer in another diffusion plate provided by the present application;

[0045] Figure 13 Sectional diagram of another diffusion plate and a light source provided by an embodiment of the present application;

[0046] Figure 14 Structure diagram of another backlight module provided by an embodiment of the present application.

[0047] Legend:

[0048] 100-backlight module, 200-display panel, 1-light source, 11-light emitting element, 2-diffusion plate, 21-substrate, 22-first diffusion structure layer, 23-second diffusion structure layer, 221-first protrusion, 222-second protrusion, 231-recess, Q-partition, T1-first protrusion part, T2-second protrusion part, 201-first diffusion plate, 202-second diffusion plate, X1-first direction, X2-second direction, X3-third direction, X4-fourth direction. DETAILED DESCRIPTION

[0049] In order to make the above objectives, features and advantages of the present application more apparent, comprehensible and easier to understand, the present application will be further described below with reference to the accompanying drawings and embodiments. However, the example embodiments can be implemented in various forms, and should not be understood as being limited to the embodiments set forth herein; on the contrary, these embodiments are provided so as to make the present application more comprehensive and complete, and to fully convey the ideas of the example embodiments to those skilled in the art. The same reference numerals in the drawings represent the same or similar structures, and thus repeated description thereof will be omitted. The words expressing position and direction described in the present application are described with reference to the drawings, but can be changed as needed, and the changes made are included in the scope of protection of the present application. The drawings of the present application are only used to illustrate the relative positional relationship and do not represent the true proportions.

[0050] Figure 1 A structural schematic diagram of a display device provided by an embodiment of the present application.

[0051] As shown in Figure 1 , the display device provided by the embodiment of the present application includes a backlight module 100 and a display panel 200, the display panel 200 is located on the light-emitting side of the backlight module 100, the display panel 200 itself does not emit light, and the backlight module 100 provides backlight for the display panel 200, and forms a display image after modulation by the display panel 200.

[0052] For example, the display panel 200 is a liquid crystal display panel, which includes an array substrate and a color film substrate arranged oppositely, has a liquid crystal layer between the array substrate and the color film substrate, and can control the deflection direction of liquid crystal molecules in the liquid crystal layer through a control circuit in the array substrate, so as to modulate the transmittance and reflectivity of incident light, thereby changing the brightness and contrast of the display image, etc. The light is converted into the required color through the color film in the color film substrate, forming a colorful display image, and polarizing sheets can also be arranged on both sides of the display panel to improve the quality of the display image. It can be understood that the specific composition of the display panel can be designed according to actual needs, and the embodiment of the present application is not limited herein.

[0053] Figure 2 A structural schematic diagram of a backlight module provided by an embodiment of the present application.

[0054] As shown in Figure 2As shown, in the embodiment of the present application, the backlight module is a direct backlight module, and the light source 1 in the backlight module may, for example, adopt a lamp panel, a plurality of light emitting elements 11 are arranged in an array on the lamp panel, and the light emitting element 11 includes but is not limited to one of a Mini LED chip, a Micro LED chip or a packaging structure thereof. In actual application, it is usually desired that the backlight module provides uniform surface light for the display panel to ensure that the display picture has good quality, and a plurality of functional film layers may be arranged in a stack on the light emitting side of the light source 1, including but not limited to a diffusion film or a diffusion plate 2 for homogenizing light, a color conversion film for converting light color, a brightness enhancement prism film for improving light brightness, etc.

[0055] Since the light emitting angle of the light emitting element 11 (LED device) is large, for example, the light emitting angle of the light emitting element 11 is usually 2θ, and θ is 60°, so that the light emitted by the light emitting element 11 at a large angle will inevitably have part of the light incident into the light emitting area of the adjacent light emitting element 11, and the light leakage phenomenon occurs. In view of this, the diffusion plate 2 in the above functional film layer is designed to improve the above light leakage problem. The diffusion plate 2 may be arranged on the side closest to the light source 1 in the plurality of functional film layers, and the specific composition and arrangement mode of the other functional film layers in the backlight module may be designed according to actual requirements, which is not limited herein, and the specific structure of the diffusion plate 2 provided by the present application will be described below.

[0056] Figure 3 A structure diagram of a first diffusion structure layer in a diffusion plate provided by an embodiment of the present application is shown. Figure 4 A cross-sectional schematic diagram of a diffusion plate and a light source provided by an embodiment of the present application is shown.

[0057] As shown in Figure 3 and Figure 4 In the embodiment of the present application, the diffusion plate 2 includes a substrate 21 and a first diffusion structure layer 22, and the first diffusion structure layer 22 is located on the surface of the substrate 21. For example, the material of the substrate 21 may be one of polyethylene terephthalate (PET), polycarbonate (PC) and polymethyl methacrylate (PMMA), and the thickness of the substrate is greater than or equal to 0.1 mm and less than or equal to 0.2 mm. The material of the first diffusion structure layer 22 may be ultraviolet glue (UV glue), and the refractive index thereof is greater than or equal to 1.58 and less than or equal to 1.70. The manufacturing process of the first diffusion structure layer 22 may be one of pressing, printing and 3D printing, and after the pattern of the first diffusion structure layer 22 is formed, it may be cured by heat curing or ultraviolet light (UV light) irradiation.

[0058] The first diffusion structure layer 22 comprises a first protrusion 221 and a second protrusion 222, the height of the first protrusion 221 is greater than the height of the second protrusion 222, and the pattern of the first protrusion 221 divides the first diffusion structure layer 22 into a plurality of sub-zones Q, and the second protrusion 222 is located in each sub-zone Q divided by the first protrusion 221.

[0059] As shown in the drawings, the first diffusion structure layer 22 is arranged to face the light source 1, and each light emitting element 11 in the light source 1 is arranged to correspond to a sub-zone Q of the first diffusion structure layer 22, so that the large-angle light rays emitted by the light emitting element 11 can be incident to the first protrusion 221 at the edge of the corresponding sub-zone Q, and the small-angle light rays are incident to the second protrusion 222 in the corresponding sub-zone Q. Figure 4

[0060] Specifically, the large-angle light rays emitted by the light emitting element 11 are incident to the first protrusion 221, and at the interface between air and the first protrusion 221, the light rays emitted by the light emitting element 11 at a large angle can be emitted to the inside of the substrate 21 at a smaller angle, reducing the amount of light incident to the adjacent sub-zone Q, thereby improving the phenomenon that the large-angle light rays emitted by the light emitting element 11 leak into the light emitting range of the adjacent light emitting element 11, and facilitating the improvement of the contrast of the display picture and the quality of the display picture.

[0061] In the height direction of the first protrusion 221 and the second protrusion 222, the orthographic projection of the light emitting element 11 can be located at the center position of the orthographic projection of the corresponding sub-zone Q, so that the first protrusion 221 can act on the light rays in the same light emitting angle range of the light emitting element 11, and the light leakage phenomenon on one side of the sub-zone Q is avoided. The following embodiments are described based on this case.

[0062] In the embodiment of the present application, the distance between the light source 1 and the diffusion plate 2 can satisfy the following relationship:

[0063] L1=2×(h1+H)×tanθ

[0064] The distance between the light source 1 and the diffusion plate 2 can satisfy the following relationship:

[0065] L1=n×L2

[0066] Wherein, L1 represents the distance between the light emitting elements 11; h1 represents the height of the first protrusion 221; H represents the distance between the light emitting element 11 and the first diffusion structure layer; θ represents half of the light emitting angle of the light emitting element 11; L2 represents the width of the sub-zone Q corresponding to the light emitting element 11; and n is an integer, indicating that each light emitting element 11 in the light source 1 can also be arranged to correspond to a plurality of sub-zones Q in the first diffusion structure layer 22.

[0067] ​By controlling the partitions Q divided by the first protrusion 221 to satisfy the above relationship, the large-angle light emitted by the light-emitting element 11 can be incident on the first protrusion 221 at the edge of one or more corresponding partitions Q, thereby improving the light leakage phenomenon to a greater extent.

[0068] like Figure 3 As shown, in this embodiment of the invention, the first protrusion 221 includes a plurality of first protrusions T1; some of the first protrusions T1 extend along a first direction X1, and the plurality of first protrusions T1 extending along the first direction X1 are spaced apart along the first direction X2; other first protrusions T1 extend along the first direction X2, and the plurality of first protrusions T1 extending along the first direction X2 are spaced apart along the first direction X1, and the first direction X1 and the first direction X2 intersect. It can be seen that the first protrusions T1 can be columnar structures, and the pattern of the first protrusion 221 composed of the plurality of first protrusions T1 is grid-like, dividing the first diffusion layer into a plurality of rectangular partitions Q. Further, the shape of the partitions Q can be square.

[0069] The shape and size of the first protrusion T1 can be designed according to actual needs so that more of the large-angle light emitted from the light-emitting element 11 can be incident on the first protrusion 221, or so that the light incident on the first protrusion 221 can be refracted to a greater extent, that is, emitted into the substrate 21 at a smaller angle, thus avoiding light leakage.

[0070] For example, in the direction perpendicular to the substrate 21 and pointing from the substrate 21 to the first diffusion structure layer 22, the cross-sectional area of ​​the first protrusion T1 gradually decreases, and the width and height of the first protrusion T1 can satisfy the following relationship:

[0071] (R1) / 2≤h1≤R1

[0072] Wherein, R1 represents half the width of the first protrusion T1, and the width of the first protrusion T1 is the width of the cross-section of the first protrusion T1 in the extending direction; h1 represents the height of the first protrusion T1.

[0073] For example, such as Figure 3 As shown, in the direction perpendicular to the substrate 21, the cross-sectional shape of the first protrusion T1 is semi-circular, and R1 in the above relationship represents the radius of the first protrusion T1. For example, the radius R1 of the first protrusion T1 is greater than or equal to 0.01 mm and less than or equal to 0.1 mm.

[0074] Generally, the intensity of the light beam emitted by the light emitting element 11 (LED device) decreases as the light emitting angle increases, that is, more light is received in the central region of the sub-region Q corresponding to the light emitting element 11, and less light is received closer to the edge of the sub-region Q. In the embodiments of the present application, the second protrusion 222 is arranged in the sub-region Q, so that the small-angle light emitted by the light emitting element 11 is incident on the second protrusion 222 in the corresponding sub-region Q. At least part of the light is incident on the inside of the substrate 21 after multiple reflections between the second protrusion 222 and the substrate 21. The light emitted by the light emitting element 11 towards the central region of the corresponding sub-region Q can be diverted to a position closer to the edge of the sub-region Q, so that the light beam emitted by the light emitting element 11 is more uniform after passing through the second protrusion 222 in the corresponding sub-region Q, which is beneficial to improve the uniformity of the backlight brightness, and further improve the quality of the display picture.

[0075] In some embodiments of the present application, the second protrusion 222 includes a plurality of second protrusion portions T2. In each sub-region Q, part of the plurality of second protrusion portions T2 extend along a third direction X3, and the plurality of second protrusion portions T2 extending along the third direction X3 are arranged along a fourth direction X4. Other second protrusion portions T2 of the plurality of second protrusion portions T2 extend along the fourth direction X4, and the plurality of second protrusion portions T2 extending along the fourth direction X4 are arranged along the third direction X3. The third direction X3 and the fourth direction X4 intersect, wherein the third direction X3 can be the same as or different from the first direction X1 described above, and the fourth direction X4 can be the same as or different from the first direction X2 described above, which is not limited herein. In the embodiments of the present application, the third direction X3 is the same as the first direction X1, and the fourth direction X4 is the same as the first direction X2.

[0076] As can be seen, the second protrusion portion T2 can also be a columnar structure. In each sub-region Q, the pattern of the second protrusion 222 composed of a plurality of second protrusion portions T2 can be grid-shaped. The second protrusion portions T2 arranged along the third direction X3 are arranged at intervals, and the second protrusion portions T2 arranged along the fourth direction X4 are arranged at intervals. Due to the limitation of process precision, part of the adjacent second protrusion portions T2 can be connected. Therefore, in some embodiments of the present application, the second protrusion portions T2 arranged along the third direction X3 are closely arranged, and the second protrusion portions T2 arranged along the fourth direction X4 are closely arranged. Alternatively, in some other embodiments of the present application, part of the second protrusion portions T2 arranged along the third direction X3 are arranged at intervals, and part of the second protrusion portions T2 arranged along the third direction X3 are closely arranged. Part of the second protrusion portions T2 arranged along the fourth direction X4 are arranged at intervals, and part of the second protrusion portions T2 arranged along the fourth direction X4 are closely arranged. It can be understood that the second protrusion portions T2 arranged at intervals means that there is a gap between the adjacent second protrusion portions T2, and the second protrusion portions T2 are not in contact. The second protrusion portions T2 closely arranged means that the adjacent second protrusion portions T2 are in contact with each other.

[0077] The shape and size of the second protruding portion T2 can be designed according to actual requirements, so that the light incident to the center region of the sub-region Q is appropriately transferred to the region close to the edge of the sub-region Q, and the energy distribution of the light beam emitted by each light emitting element 11 when the light beam is incident to the substrate 21 through the first diffusion structure layer 22 is as uniform as possible.

[0078] For example, the width and height of the second protruding portion T2 can satisfy the following relationship:

[0079] (R2) / 2≤h2≤R2

[0080] wherein R2 represents half of the width of the second protruding portion T2, the width of the second protruding portion T2 is the width of the cross section of the second protruding portion T2 in the extending direction; and h2 represents the height of the second protruding portion T2.

[0081] For example, as shown in Figure 3 in the direction perpendicular to the substrate 21 and directed from the substrate 21 to the first diffusion structure layer 22, the cross-sectional area of the second protruding portion T2 gradually decreases, and in the direction perpendicular to the substrate 21, the cross-sectional shape of the second protruding portion T2 is semicircular, R2 in the above relationship represents the radius of the second protruding portion T2.

[0082] For example, the width of the first protruding portion T1 and the width of the second protruding portion T2 can satisfy the following relationship:

[0083] 2R2≤R1≤3R2

[0084] wherein R1 represents half of the width of the first protruding portion T1, the width of the first protruding portion T1 is half of the width of the cross section of the first protruding portion T1 in the extending direction; and R2 represents the width of the second protruding portion T2, the width of the second protruding portion T2 is the width of the cross section of the second protruding portion T2 in the extending direction.

[0085] For example, the height of the first protruding portion T1 and the height of the second protruding portion T2 can satisfy the following relationship:

[0086] 2h2≤h1≤3h2

[0087] wherein h1 represents the height of the first protruding portion T1; and h2 represents the height of the second protruding portion T2.

[0088] Figure 5 A structure diagram of the second diffusion structure layer provided by the embodiment of the present application is shown.

[0089] For example, as shown in Figure 4 and Figure 5As shown, in this embodiment of the invention, the diffusion plate 2 further includes a second diffusion structure layer 23, which is located on the side of the substrate 21 away from the first diffusion structure layer 22. The second diffusion structure layer 23 includes a plurality of recesses 231, and the cross-sectional area of ​​the recesses 231 gradually increases in the direction perpendicular to the substrate 21 and pointing from the substrate 21 to the second diffusion structure layer 23.

[0090] The light incident on the second diffusion structure layer 23 can be reflected multiple times between the recess 231 and the substrate 21, forming multiple small beams. The light in each small beam is concentrated within a certain light emission angle range to increase the light emission brightness of the backlight module at the positive viewing angle, thereby improving the brightness of the display screen.

[0091] For example, the recesses 231 in the second diffusion structure layer 23 can be shaped like a square pyramid. The recesses 231 are arranged in an array on the surface of the second diffusion structure layer 23. The apex angle of the square pyramid is greater than or equal to 30° and less than or equal to 80°. The light emitted from the second diffusion structure layer 23 forms multiple small beams. The emission angle of each small beam can be concentrated within the aforementioned angle range, thereby improving the emission brightness and uniformity of the backlight module from the front viewing angle. Optionally, the apex angle of the square pyramid is greater than or equal to 50° and less than or equal to 70°, the base length of the square pyramid is greater than or equal to 0.01mm and less than or equal to 0.1mm, and the height of the square pyramid is greater than or equal to 0.01mm and less than or equal to 0.1mm.

[0092] To make the modulation effect of the diffuser plate 2 on the emitted light from the light source 1 clearly visible in the embodiments of the present invention, the embodiments of the present invention provide, for example... Figure 3 The diffusion plate 2 shown was subjected to simulation test. The design of the first diffusion structure layer 22 and the second diffusion structure layer 23 in the diffusion plate 2 satisfies the above formulas. The test results are explained below.

[0093] Figure 6 The brightness distribution of a single light-emitting element after modulation by a traditional diffuser plate; Figure 7 This is a brightness distribution diagram of a single light-emitting element after being modulated by the diffuser plate provided in this embodiment of the invention.

[0094] like Figure 6 As shown, when a traditional diffuser plate is used, the light emitted by the light-emitting element is a circular light spot. The brightness of the central region of the light spot is higher than that of the edge region, and the energy is concentrated in a small area in the center.

[0095] like Figure 7As shown, when the diffusion plate 2 provided by the embodiment of the present application is adopted, the light spot emitted by the light emitting element 11 is modulated by the diffusion plate 2 into a rectangular light spot. It can be seen that the diffusion plate 2 provided by the embodiment of the present application also has a shaping effect on the light beam emitted by the light emitting element 11, which is conducive to matching the pixelated structure in the display panel. In addition, compared with a circular light spot, the spacing between adjacent rectangular light spots can be smaller, which is conducive to improving the resolution of the display picture. After the light emitting element 11 is modulated by the diffusion plate 2 provided by the embodiment of the present application, the brightness of the center of the light spot emitted by the light emitting element 11 is higher than that of the edge region, but the energy distribution is relatively uniform. It can be seen that the diffusion plate 2 provided by the embodiment of the present application can homogenize the light emitted by the light emitting element 11.

[0096] Figure 8 A comparison diagram of point spread function curves of the light emitting element modulated by the traditional diffusion plate and the diffusion plate provided by the embodiment of the present application.

[0097] Figure 8 The abscissa in the diagram represents the diffusion distance of the light beam, and the unit is mm. The ordinate represents the normalized brightness of the diffusion position. The point spread function (PSF) curve can represent the degree of light leakage of the sub-area Q. The wider the PSF curve, the greater the diffusion distance of the light beam, that is, the greater the halo, and the more serious the light leakage phenomenon. Figure 8 In the diagram, the curve L1 represents the PSF curve of the light emitting element modulated by the traditional diffusion plate, and the curve L2 represents the PSF curve of the light emitting element modulated by the diffusion plate 2 provided by the embodiment of the present application. It can be seen that by adopting the diffusion plate 2 provided by the embodiment of the present application, the PSF curve can be effectively narrowed, which is conducive to reducing the halo and improving the light leakage phenomenon.

[0098] The following table corresponds to the curves shown in Figure 8 The table shows the diffusion distance of the light beam corresponding to the brightness of 50% and 1% of the peak brightness, respectively:

[0099]

[0100] As can be seen from Figure 8 and the above table, the PSF curve of the brightness of the light beam emitted by the light emitting element 11 is narrowed as a whole after being modulated by the diffusion plate 2 provided by the embodiment of the present application. In the brightness of 1% of the peak brightness, the diffusion distance is narrowed by 9%. That is, the light emitting angle range of the light beam emitted by the light emitting element 11 is reduced after being modulated by the diffusion plate 2, and the number of large-angle light rays is reduced, which is conducive to improving the phenomenon of light leakage to the adjacent sub-area Q, improving the halo, and improving the contrast of the display picture.

[0101] Figure 9 A light emission brightness distribution diagram when the diffusion plate provided by the embodiment of the present application is arranged in the backlight module.

[0102] As can be seen from Figure 9As can be seen, the energy distribution of the backlight is uniform. By setting the diffuser plate 2 provided in the embodiment of the present invention in the backlight module, the backlight can have better uniformity.

[0103] Figure 10 This is a diagram showing the brightness distribution of the light emitted after the light source has been modulated by a traditional diffuser plate. Figure 11 This is a brightness distribution diagram of the light emitted after the light source is modulated by the diffuser plate provided in this embodiment of the invention.

[0104] Illumination by light source 1 Figure 10 The 3×3 chessboard shown in (a) can be measured as follows: Figure 10 The energy distribution of the light spot shown in (b) has a brightness of L0 in the central dark square; when illuminated by light source 1... Figure 11 The 3×3 chessboard shown in (a) can be measured as follows: Figure 11 The light spot energy distribution shown in (b) has a brightness of L255 at its central bright square. The dynamic contrast ratio CR of the display device can be calculated using the brightness of the central bright and dark squares: CR = L255 / L0. The following table shows... Figure 10 (b) and Figure 11 The relevant data corresponding to the energy distribution map shown in (b) are as follows:

[0105] Conventional diffusion plate The diffusion plate provided by the embodiments of the present application L225 (unit: nit) 33826 35545 L0 (unit: nit) 238 135 Dynamic CR 142 263 Dynamic CR boost ratio 100％ 185％

[0106] As can be seen from the table above, by using the diffuser plate 2 provided in the embodiment of the present invention, the bright areas of the backlight can be made brighter and the dark areas darker, thereby improving the contrast of the backlight and thus improving the contrast of the displayed image, with a contrast improvement of 85%.

[0107] Figure 12 A schematic diagram of the structure of the first diffusion structure layer in another diffusion plate provided by the present invention; Figure 13 This is a cross-sectional schematic diagram of another diffuser plate and light source provided in an embodiment of the present invention.

[0108] like Figure 12 and Figure 13 As shown, in this embodiment of the invention, the diffuser plate 2 and Figure 3 and Figure 4 The difference in the illustrated embodiment is that the first protrusion T1 and the second protrusion T2 are triangular prisms. In the direction perpendicular to the substrate 21, the cross-sectional shape of the first protrusion T1 is triangular. When fabricating the first diffusion structure layer 22 in this embodiment using processes such as pressing, the mold fabrication is less difficult.

[0109] Exemplarily, in the embodiment of the present application, the top angle a1 of the first protruding part T1 and the top angle a2 of the second protruding part T2 can satisfy a1=a2=180°-2θ, so that as many light rays emitted by the light emitting element 11 as possible are limited within the corresponding subzone Q. Other dimensions of the first protruding part 221 and the second protruding part 222 can satisfy the limiting conditions as shown in the embodiments of Figure 3 and Figure 4 and will not be described herein.

[0110] Figure 14 Another structure schematic diagram of the backlight module provided by the embodiment of the present application.

[0111] As shown in Figure 14 , the backlight module can include two diffusion plates, which are stacked and include a first diffusion plate 201 and a second diffusion plate 202. The second diffusion plate 202 is located on the side of the first diffusion plate 201 away from the light source 1. The first diffusion structure layer 22 of the first diffusion plate 201 faces the light source 1, and the first diffusion structure layer of the second diffusion plate 202 faces the first diffusion plate 201. The two diffusion plates in the backlight module can homogenize the light to a greater extent and improve the uniformity of the backlight. The first diffusion plate 201 and the second diffusion plate 202 can be any of the diffusion plates as shown in Figure 3 or Figure 12 The structures of the two diffusion plates can be the same or different.

[0112] Although the preferred embodiments of the present application have been described, those skilled in the art can make further changes and modifications to these embodiments once they know the basic inventive concept. Therefore, the appended claims are intended to be interpreted as including all changes and modifications falling within the scope of the present application.

[0113] Obviously, those skilled in the art can make various modifications and variations to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalent technologies, the present application also intends to include these modifications and variations.

Claims

1. A diffusion plate, wherein, The diffusion plate comprises a substrate and a first diffusion structure layer on a surface of the substrate; The first diffusion structure layer comprises first protrusions and second protrusions, the height of the first protrusions is greater than the height of the second protrusions, and a pattern of the first protrusions divides the first diffusion structure layer into a plurality of sub-zones, and the second protrusions are located in the sub-zones; The first protrusions are used for refracting incident light into the substrate, and the second protrusions are used for reflecting at least part of the incident light multiple times and then emitting the light out of the substrate; The first protrusions comprise a plurality of first protrusion portions, part of the first protrusion portions extend along a first direction, a plurality of the first protrusion portions extending along the first direction are arranged along a second direction, other first protrusion portions extend along the second direction, a plurality of the first protrusion portions extending along the second direction are arranged along the first direction, and the first direction and the second direction intersect.

2. The diffusion plate of claim 1, wherein, The second protrusions comprise a plurality of second protrusion portions, in each of the sub-zones, part of the second protrusion portions extend along a third direction, and a plurality of the second protrusion portions extending along the third direction are arranged along a fourth direction; Other second protrusion portions extend along the fourth direction, and a plurality of the second protrusion portions extending along the fourth direction are arranged along the third direction, and the third direction and the fourth direction intersect.

3. The diffusion plate of claim 2, wherein, At least part of adjacent second protrusion portions arranged along the third direction are arranged in a spaced manner or in a contacting manner, and at least part of adjacent second protrusion portions arranged along the fourth direction are arranged in a spaced manner or in a contacting manner.

4. The diffusion plate of claim 2 or 3, wherein, In a direction perpendicular to the substrate and pointing from the substrate to the first diffusion structure layer, the cross-sectional area of the first protrusion portion gradually decreases.

5. The diffusion plate of claim 4, wherein, The width and the height of the first protrusion portion satisfy the following relationship: wherein represents half of the width of the first protruding portion, the width of the first protruding portion being the width of the cross section of the first protruding portion in the extending direction; represents the height of the first protruding portion.

6. The diffusion plate of claim 4, wherein, The width and the height of the second protrusion portion satisfy the following relationship: wherein represents half of the width of the second protruding portion, the width of the second protruding portion being the width of the cross section of the second protruding portion in the extending direction; represents the height of the second protruding portion.

7. The diffusion plate of claim 4, wherein, The width of the first protrusion portion and the second protrusion portion satisfies the following relationship: wherein represents half of the width of the first protruding portion, the width of the first protruding portion being half of the width of a cross section of the first protruding portion in the extending direction; represents the width of the second protruding portion, the width of the second protruding portion being the width of a cross section of the second protruding portion in the extending direction.

8. The diffusion plate of claim 4, wherein, The height of the first protrusion portion and the second protrusion portion satisfies the following relationship: wherein represents the height of the first protrusion; represents the height of the second protrusion.

9. The diffusion plate of claim 1, wherein, The diffusion plate further comprises a second diffusion structure layer on a side of the substrate away from the first diffusion structure layer, and the second diffusion structure layer comprises a plurality of recessed portions, in a direction perpendicular to the substrate and pointing from the substrate to the second diffusion structure layer, the cross-sectional area of the recessed portion gradually increases.

10. The diffusion plate of claim 9, wherein, The recessed portion is a quadrangular pyramid, the apex angle of the quadrangular pyramid is greater than or equal to 30°, and the apex angle of the quadrangular pyramid is less than or equal to 80°.

11. A backlight module, comprising: The backlight module comprises a light source and the diffusion plate according to any one of claims 1-10, the first diffusion structure layer of the diffusion plate faces the light source, the light source comprises a plurality of light emitting elements, each of the light emitting elements corresponds to one or more sub-zones of the first diffusion structure layer, and in the height direction of the first protrusions and the second protrusions, the orthographic projection of the light emitting element is located at the center position of the orthographic projection of the corresponding one or more sub-zones.

12. The backlight module of claim 11, wherein, The distance between the light source and the diffusion plate satisfies the following relationship: wherein, represents a pitch of adjacent light emitting elements; 1 represents a height of the first protrusion; represents a pitch of the light emitting elements and the first diffusion structure layer; represents a half of a light emitting angle of the light emitting elements.

13. The backlight module of claim 11 or 12, wherein, The backlight module comprises two diffusion plates, the two diffusion plates comprising a first diffusion plate and a second diffusion plate, the second diffusion plate being located on a side of the first diffusion plate away from the light source, a first diffusion structure layer of the first diffusion plate facing the light source, and a first diffusion structure layer of the second diffusion plate facing the first diffusion plate.

14. A display device, wherein, The display device comprises a display panel and the backlight module according to any one of claims 11-13, the display panel being located on a light-out side of the backlight module.

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