Diffusion plate, backlight module and display device

Abstract

Disclosed in the present invention are a diffusion plate, a backlight module and a display device. The diffusion plate comprises: a substrate and a first diffusion structure layer, the first diffusion structure layer being located on the surface of the substrate. The first diffusion structure layer comprises first protrusions and second protrusions, wherein the pattern of the first protrusions divides the first diffusion structure layer into a plurality of regions, and the second protrusions are located in the regions, the height of the second protrusions being less than that of the first protrusions. The first protrusions are used for refracting incident light rays into the substrate, converting large-angle light rays into light rays emitted at smaller angles, and reducing the occurrence of total reflection, thereby alleviating the problem of light leakage into adjacent regions. The second protrusions are used for reflecting at least some incident light rays multiple times, which are then emitted from the substrate, thereby making light rays more uniform.

Description

Diffusion plate, backlight module and display device

[0001] Cross-reference to related applications

[0002] The present application claims priority to the Chinese patent application No. 202411109890.X, filed on August 13, 2024, and entitled "A diffusion plate, backlight module and display device", the whole content of which is incorporated herein by reference. TECHNICAL FIELD

[0003] The present application relates to the field of display technology, in particular to a diffusion plate, a backlight module and a display device. BACKGROUND

[0004] 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 array of Mini LED or Micro LED as the backlight source of the liquid crystal display panel (LCD for short), can divide the backlight module into independently controllable partitions, and presents a brighter or darker picture through the local area dimming technology, so as to improve the dynamic contrast of the liquid crystal display panel by means of the High Dynamic Range Imaging (HDR for short) technology, and has the advantages of high contrast, high brightness, thin and light, etc.

[0005] However, in the backlight source, the light emitted by a certain partition may leak into the adjacent non-light-emitting partition, resulting in a light leakage phenomenon, i.e., a Halo Effect, and thus reducing the contrast of the display picture and affecting the quality of the display picture. SUMMARY

[0006] The present application provides a diffusion plate, a backlight module and a display device to prevent the light leakage phenomenon between the partitions of the backlight source and improve the contrast and brightness of the display picture.

[0007] 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 being located on a surface of the substrate; the first diffusion structure layer comprising first protrusions and second protrusions, a height of the first protrusions being greater than a height of the second protrusions, a pattern of the first protrusions dividing the first diffusion structure layer into a plurality of sub-zones, the second protrusions being located in the sub-zones; the first protrusions being configured to refract incident light into the substrate, and the second protrusions being configured to reflect at least part of the incident light multiple times and then out of the substrate.

[0008] 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, the first direction and the second direction being intersected.

[0009] In some embodiments of the present application, the second protrusions comprise a plurality of second protrusion portions; in each of the sub-zones, some 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 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, the third direction and the fourth direction being intersected.

[0010] 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 manner or in a contacting manner; at least some of the second protrusion portions arranged along the fourth direction are arranged in a spaced manner or in a contacting manner.

[0011] In some embodiments of the present application, in a direction perpendicular to the substrate and pointing from the substrate to the first diffusion structure layer, an area of a cross section of the first protrusion portion gradually decreases.

[0012] In some embodiments of the present application, a width and a height of the first protrusion portion satisfy the following relationship: (R1) / 2≤h1≤R1

[0013] wherein R1 represents half of the width of the first protrusion portion, the width of the first protrusion portion being a width of a cross section of the first protrusion portion in the extending direction; and h1 represents the height of the first protrusion portion.

[0014] In some embodiments of the present application, a width and a height of the second protrusion portion satisfy the following relationship: (R2) / 2≤h2≤R2

[0015] wherein R2 represents half of 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; and h2 represents the height of the second protruding part.

[0016] In some embodiments of the present application, the width of the first protruding part and the second protruding part satisfies the following relationship: 2R2≤R1≤3R2

[0017] 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.

[0018] In some embodiments of the present application, the height of the first protruding part and the second protruding part satisfies the following relationship: 2h2≤h1≤3h2

[0019] wherein h1 represents the height of the first protruding part; and h2 represents the height of the second protruding part.

[0020] 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, in the direction perpendicular to the substrate and directed from the substrate to the second diffusion structure layer, the area of the cross section of the recessed part gradually increases.

[0021] 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°.

[0022] 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.

[0023] In some embodiments of the present application, the distance between the light source and the diffusion plate satisfies the following relationship: L1=2×(h1+H)×tanθ

[0024] 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.

[0025] 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.

[0026] 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.

[0027] The present application has the following advantages:

[0028] 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 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, thereby homogenizing the light. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiments of the present application will be briefly introduced as follows. 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.

[0030] FIG. 1 is a structural schematic diagram of a display device provided by an embodiment of the present application;

[0031] FIG. 2 is a structural schematic diagram of a backlight module provided by an embodiment of the present application;

[0032] FIG. 3 is a structural schematic diagram of a first diffusion structure layer in a diffusion plate provided by an embodiment of the present application;

[0033] FIG. 4 is a sectional schematic diagram of a diffusion plate and a light source provided by an embodiment of the present application;

[0034] FIG. 5 is a structural schematic diagram of a second diffusion structure layer provided by an embodiment of the present application;

[0035] FIG. 6 is a light-out brightness distribution diagram of a single light-emitting element modulated by a traditional diffusion plate;

[0036] Fig. 7 is a light intensity distribution diagram of a single light emitting element modulated by a diffusion plate according to an embodiment of the present application;

[0037] Fig. 8 is a comparison diagram of point spread function curves of a light emitting element modulated by a conventional diffusion plate and a diffusion plate according to an embodiment of the present application;

[0038] Fig. 9 is a light intensity distribution diagram of a backlight module provided with a diffusion plate according to an embodiment of the present application;

[0039] Fig. 10 is a light intensity distribution diagram of a light source modulated by a conventional diffusion plate;

[0040] Fig. 11 is a light intensity distribution diagram of a light source modulated by a diffusion plate according to an embodiment of the present application;

[0041] Fig. 12 is a structure diagram of a first diffusion structure layer in another diffusion plate according to the present application;

[0042] Fig. 13 is a sectional diagram of another diffusion plate and a light source according to an embodiment of the present application;

[0043] Fig. 14 is a structure diagram of another backlight module according to an embodiment of the present application.

[0044] Legend: 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

[0045] In order to make the above objectives, features and advantages of the present application more apparent, further description will be given below in conjunction with 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 described herein; on the contrary, these embodiments are provided 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. Identical reference numerals in the drawings represent identical or similar structures, and thus repeated description thereof will be omitted. The expressions of 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 show the relative position relationship and do not represent the true proportions.

[0046] Fig. 1 is a structure diagram of a display device according to an embodiment of the present application.

[0047] As shown in FIG. 1, the display device provided by the embodiment of the present application comprises a backlight module 100 and a display panel 200, the display panel 200 is located at the light exit side of the backlight module 100, the display panel 200 itself does not emit light, the backlight module 100 provides backlight for the display panel 200, and the display image is formed after the modulation of the display panel 200.

[0048] For example, the display panel 200 is a liquid crystal display panel, comprising an array substrate and a color film substrate arranged oppositely, and a liquid crystal layer between the array substrate and the color film substrate, the deflection direction of the liquid crystal molecules in the liquid crystal layer can be controlled by the control circuit in the array substrate, so as to modulate the transmittance and reflectivity of the incident light, thereby changing the brightness and contrast of the display image, the light is converted into the required color by the color film in the color film substrate, and the color display image is formed, 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, which is not limited in the embodiment of the present application.

[0049] FIG. 2 is a structural schematic diagram of a backlight module provided by the embodiment of the present application.

[0050] As shown in FIG. 2, in the embodiment of the present application, the backlight module is a direct type backlight module, the light source 1 in the backlight module can 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 image has good quality, and a plurality of functional film layers can be arranged in a stack on the light exit 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.

[0051] 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 2θ, and θ is 60°, so that part of the light emitted by the light emitting element 11 at a large angle will inevitably be incident into the light exit 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-mentioned functional film layers is designed to improve the above-mentioned light leakage problem. The diffusion plate 2 can be arranged on the side closest to the light source 1 among the plurality of functional film layers, and the specific composition and arrangement mode of the other functional film layers in the backlight module can be designed according to actual needs, which is not limited herein, and the specific structure of the diffusion plate 2 provided by the present application will be described below.

[0052] Fig. 3 is a structural schematic diagram of a first diffusion structure layer in a diffusion plate according to an embodiment of the present application; and Fig. 4 is a sectional schematic diagram of a diffusion plate and a light source according to an embodiment of the present application.

[0053] As shown in Figs. 3 and 4, in the embodiment of the present application, the diffusion plate 2 comprises 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. Exemplarily, the material of the substrate 21 can be one of, but not limited to, 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 can be ultraviolet glue (UV glue), and the refractive index of the ultraviolet glue is greater than or equal to 1.58 and less than or equal to 1.70; and the manufacturing process of the first diffusion structure layer 22 can be one of pressing, printing, and 3D printing, and after the pattern of the first diffusion structure layer 22 is formed, the first diffusion structure layer 22 can be cured by using heat curing or ultraviolet light (UV light) irradiation.

[0054] The first diffusion structure layer 22 comprises first protrusions 221 and second protrusions 222, the height of the first protrusions 221 is greater than the height of the second protrusions 222, and the pattern of the first protrusions 221 divides the first diffusion structure layer 22 into a plurality of sub-zones Q, and the second protrusions 222 are located in each sub-zone Q divided by the first protrusions 221.

[0055] As shown in Fig. 4, 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 corresponds to one 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 protrusions 221 at the edge of the corresponding sub-zone Q, and the small-angle light rays are incident to the second protrusions 222 in the corresponding sub-zone Q.

[0056] Specifically, the large-angle light rays emitted by the light emitting element 11 are incident to the first protrusions 221, and at the interface between air and the first protrusions 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, thereby reducing the amount of light rays incident to the adjacent sub-zone Q, and 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, which is beneficial to improve the contrast of the display picture and improve the quality of the display picture.

[0057] 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 partition 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 partition Q is avoided. The following embodiments are described based on this case.

[0058] In the embodiment of the present application, the distance between the light source 1 and the diffusion plate 2 can satisfy the following relationship: L1 = 2 × (h1 + H) × tanθ

[0059] The distance between the adjacent light emitting elements 11 and the width of the corresponding partition Q satisfy the following relationship:

[0060] L1 = n × L2

[0061] Wherein, L1 represents the distance between the adjacent 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 corresponding partition Q of the light emitting element 11; and n is an integer, indicating that each light emitting element 11 in the light source 1 can also correspond to multiple partitions Q in the first diffusion structure layer 22.

[0062] By controlling the partition 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 into the first protrusion 221 at the edge of the corresponding one or more partitions Q, and the light leakage phenomenon is improved to a greater extent.

[0063] As shown in FIG. 3, in the embodiment of the present application, the first protrusion 221 includes a plurality of first protrusion portions T1; some of the plurality of first protrusion portions T1 extend along the first direction X1, and the plurality of first protrusion portions T1 extending along the first direction X1 are arranged at intervals along the first direction X2; other first protrusion portions T1 of the plurality of first protrusion portions T1 extend along the first direction X2, and the plurality of first protrusion portions T1 extending along the first direction X2 are arranged at intervals along the first direction X1, and the first direction X1 and the first direction X2 intersect. It can be seen that the first protrusion portion T1 can be a columnar structure, and the pattern of the first protrusion 221 composed of a plurality of first protrusion portions T1 is a grid shape, which divides the first diffusion layer into a plurality of rectangular partitions Q, and further, the shape of the partition Q can be a square.

[0064] The shape and size of the first protrusion portion T1 can be designed according to actual needs, so that the large-angle light emitted by the light emitting element 11 can be incident into the first protrusion 221 more, or the light incident into the first protrusion 221 can be refracted to a greater extent, i.e. emitted at a smaller angle into the inside of the substrate 21, to avoid the light leakage phenomenon.

[0065] Exemplarily, in the direction perpendicular to the substrate 21 and directed to the first diffusion structure layer 22 by the substrate 21, the cross-sectional area of the first protruding portion T1 gradually decreases, and the width and height of the first protruding portion T1 can satisfy the following relationship: (R1) / 2≤h1≤R1

[0066] wherein R1 represents half of the width of the first protruding portion T1, the width of the first protruding portion T1 being the width of the cross-section of the first protruding portion T1 in the extending direction; and h1 represents the height of the first protruding portion T1.

[0067] Exemplarily, as shown in FIG. 3, in the direction perpendicular to the substrate 21, the cross-sectional shape of the first protruding portion T1 is semicircular, and R1 in the above relationship represents the radius of the first protruding portion T1. Exemplarily, the radius R1 of the first protruding portion T1 is greater than or equal to 0.01 mm and less than or equal to 0.1 mm.

[0068] Generally, the intensity of the light beam emitted by the light emitting element 11 (LED device) decreases as the light emission 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 to the second protrusion 222 in the corresponding sub-region Q, and at least part of the light is incident to 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 be emitted at 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.

[0069] In some embodiments of the present application, the second protrusion 222 includes a plurality of second protruding portions T2. In each sub-region Q, part of the plurality of second protruding portions T2 extend along a third direction X3, and the plurality of second protruding portions T2 extending along the third direction X3 are arranged along a fourth direction X4; the other second protruding portions T2 of the plurality of second protruding portions T2 extend along the fourth direction X4, and the plurality of second protruding portions T2 extending along the fourth direction X4 are arranged along the third direction X3, and 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, and the embodiments of the present application are exemplarily described in the case that 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.

[0070] It can be seen that the second protruding portion T2 can also be a columnar structure, and the pattern of the second protrusions 222 composed of a plurality of second protruding portions T2 in each sub-area Q can be grid-shaped, with each second protruding portion T2 arranged in the third direction X3 being spaced apart and each second protruding portion T2 arranged in the fourth direction X4 being spaced apart. Due to the limitation of process precision, some of the adjacent second protruding portions T2 can be connected, and therefore, in some embodiments of the present application, each second protruding portion T2 arranged in the third direction X3 is closely arranged, and each second protruding portion T2 arranged in the fourth direction X4 is closely arranged; or in some other embodiments of the present application, some of the second protruding portions T2 arranged in the third direction X3 are partially spaced apart and partially closely arranged, and some of the second protruding portions T2 arranged in the fourth direction X4 are partially spaced apart and partially closely arranged.

[0071] It can be understood that the second protruding portion T2 being spaced apart means that there is a gap between adjacent second protruding portions T2, and the second protruding portions T2 are not in contact with each other, and the second protruding portion T2 being closely arranged means that adjacent second protruding portions T2 are arranged in contact with each other.

[0072] The shape and size of the second protruding portion T2 can be designed according to actual requirements, so that the light incident to the central area of the sub-area Q is appropriately transferred to the area close to the edge of the sub-area 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.

[0073] For example, the width and height of the second protruding portion T2 can satisfy the following relationship: (R2) / 2≤h2≤R2

[0074] wherein R2 represents half of the width of the second protruding portion T2, the width of the second protruding portion T2 being 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.

[0075] For example, as shown in FIG. 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, and in the above relationship, R2 represents the radius of the second protruding portion T2.

[0076] For example, the width of the first protruding portion T1 and the width of the second protruding portion T2 can satisfy the following relationship: 2R2≤R1≤3R2

[0077] wherein R1 represents half of the width of the first protruding portion T1, the width of the first protruding portion T1 being 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 being the width of the cross section of the second protruding portion T2 in the extending direction.

[0078] Exemplarily, the height of the first protruding part T1 and the second protruding part T2 can satisfy the following relationship: 2h2≤h1≤3h2

[0079] Wherein, h1 represents the height of the first protruding part T1; h2 represents the height of the second protruding part T2.

[0080] Fig. 5 is a structural schematic diagram of a second diffusion structure layer provided by an embodiment of the present application.

[0081] As shown in Fig. 4 and Fig. 5, in an embodiment of the present application, the diffusion plate 2 further comprises 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 comprises a plurality of recessed parts 231, and the cross-sectional area of the recessed part 231 gradually increases in the direction perpendicular to the substrate 21 and directed from the substrate 21 to the second diffusion structure layer 23.

[0082] The light rays incident to the second diffusion structure layer 23 can be reflected multiple times between the recessed part 231 and the substrate 21, and form a plurality of small light beams, and the light rays in each small light beam are concentrated in a certain light-emitting angle range for emission, so as to increase the light-emitting brightness of the normal viewing angle of the backlight module, thereby improving the brightness of the display picture.

[0083] Exemplarily, the shape of the recessed part 231 in the second diffusion structure layer 23 can be a quadrangular pyramid, the recessed parts 231 are arranged in an array on the surface of the second diffusion structure layer 23, the top angle of the quadrangular pyramid is greater than or equal to 30° and less than or equal to 80°, and the light rays emitted from the second diffusion structure layer 23 form a plurality of small light beams, and the light-emitting angle of each small light beam can be concentrated in the above-mentioned angle range, thereby improving the light-emitting brightness of the normal viewing angle of the backlight module and the uniformity of the backlight. Optionally, the top angle of the quadrangular pyramid is greater than or equal to 50° and less than or equal to 70°, the length of the bottom side of the quadrangular pyramid is greater than or equal to 0.01 mm and less than or equal to 0.1 mm, and the height of the quadrangular pyramid is greater than or equal to 0.01 mm and less than or equal to 0.1 mm.

[0084] In order to make the modulation effect of the diffusion plate 2 provided by an embodiment of the present application on the light rays emitted by the light source 1 intuitive and visible, the diffusion plate 2 shown in Fig. 3 is simulated and tested in an embodiment of the present application, the design of the first diffusion structure layer 22 and the second diffusion structure layer 23 in the diffusion plate 2 satisfies the above-mentioned formulas, and the test results are described below.

[0085] Fig. 6 is a light-emitting brightness distribution diagram of a single light-emitting element after modulation by a traditional diffusion plate; and Fig. 7 is a light-emitting brightness distribution diagram of a single light-emitting element after modulation by the diffusion plate provided by an embodiment of the present application.

[0086] As shown in FIG. 6, when the conventional diffusion plate is used, the light spot 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 range in the center.

[0087] As shown in FIG. 7, when the diffusion plate 2 provided by the embodiment of the present application is used, 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 the 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 more 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.

[0088] FIG. 8 is a comparison diagram of point spread function curves of the light emitting element modulated by the conventional diffusion plate and the diffusion plate provided by the embodiment of the present application.

[0089] The abscissa in FIG. 8 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-region 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. In FIG. 8, curve L1 represents the PSF curve of the light emitting element modulated by the conventional diffusion plate, and 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 the use of the diffusion plate 2 provided by the embodiment of the present application can effectively narrow the PSF curve, which is conducive to reducing the halo and improving the light leakage phenomenon.

[0090] The following table corresponds to the curves shown in FIG. 8, and shows the diffusion distance of the light beam at the brightness of 50% and 1% of the peak brightness, respectively:

[0091] As can be seen from FIG. 8 and the above table, the PSF curve of the brightness of the light beam emitted by the light emitting element 11 modulated by the diffusion plate 2 provided by the embodiment of the present application is narrowed as a whole. Among them, at 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 after being modulated by the diffusion plate 2 is smaller, and the number of large-angle light rays is reduced, which is conducive to improving the phenomenon of light leakage to the adjacent sub-region Q, improving the halo and improving the contrast of the display picture.

[0092] FIG. 9 is a light emitting brightness distribution diagram when the diffusion plate provided by the embodiment of the present application is arranged in the backlight module.

[0093] As shown in FIG. 9, the backlight has a uniform energy distribution. The backlight has a good uniformity when the diffusion plate 2 provided by the embodiment of the present application is arranged in the backlight module.

[0094] FIG. 10 is a diagram showing the light intensity distribution of a light source modulated by a conventional diffusion plate; and FIG. 11 is a diagram showing the light intensity distribution of a light source modulated by the diffusion plate provided by the embodiment of the present application.

[0095] The light source 1 irradiates a 3x3 chessboard shown in (a) of FIG. 10, and the energy distribution of the light spot can be measured as shown in (b) of FIG. 10, in which the brightness of the central dark square is L0. The light source 1 irradiates a 3x3 chessboard shown in (a) of FIG. 11, and the energy distribution of the light spot can be measured as shown in (b) of FIG. 11, in which the brightness of the central light square is L255. The dynamic contrast ratio CR of the display device can be calculated by the brightness of the central light square and the central dark square, CR=L255 / L0. The following table shows the relevant data corresponding to the energy distribution diagrams shown in (b) of FIG. 10 and (b) of FIG. 11:

[0096] As shown in the above table, the diffusion plate 2 provided by the embodiment of the present application can make the bright area of the backlight brighter and the dark area darker, thereby improving the contrast ratio of the backlight and further improving the contrast ratio of the display picture. The contrast ratio is improved by 85%.

[0097] FIG. 12 is a diagram showing the structure of a first diffusion structure layer in another diffusion plate provided by the present application; and FIG. 13 is a diagram showing the cross section of another diffusion plate and a light source provided by the embodiment of the present application.

[0098] As shown in FIG. 12 and FIG. 13, the diffusion plate 2 in the embodiment of the present application is different from the embodiment shown in FIG. 3 and FIG. 4 in that the shapes of the first protruding part T1 and the second protruding part T2 are triangular prisms. In the direction perpendicular to the substrate 21, the cross section of the first protruding part T1 is a triangle. When the first diffusion structure layer 22 in the embodiment of the present application is manufactured by using a process such as pressing, the difficulty in manufacturing the mold is relatively small.

[0099] For example, in the embodiment of the present application, the top angle α1 of the first protruding part T1 and the top angle α2 of the second protruding part T2 can satisfy α1=α2=180°-2θ, so that as many light rays as possible emitted by the light emitting element 11 are limited within the corresponding sub-area Q. The other dimensions of the first protruding part 221 and the second protruding part 222 can satisfy the limiting conditions as shown in the embodiment of FIG. 3 and FIG. 4, which will not be described herein.

[0100] FIG. 14 is a diagram showing the structure of another backlight module provided by the embodiment of the present application.

[0101] As shown in FIG. 14, two diffusion plates can be included in the backlight module, the two diffusion plates are stacked, including 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. Two diffusion plates are provided in the backlight module, which 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 one of the diffusion plates in the embodiments shown in FIG. 3 or FIG. 12, and the structures of the two can be the same or different.

[0102] Although preferred embodiments of the application have been described, those skilled in the art will be able to make additional changes and modifications to these embodiments once they have been given the basic inventive concept. Therefore, the appended claims are intended to be interpreted as including all changes and modifications that fall within the scope of the application.

[0103] 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.

2. The diffusion plate of claim 1, wherein, 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.

3. The diffusion plate of claim 2, 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.

4. The diffusion plate of claim 3, 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.

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

6. The diffusion plate of claim 5, wherein, The width and the height of the first protrusion portion satisfy the following relationship: (R1) / 2≤h1≤R1 wherein R1 represents half of the width of the first protrusion portion, the width of the first protrusion portion is 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.

7. The diffusion plate of claim 5, wherein, The width and the height of the second protrusion portion satisfy the following relationship: (R2) / 2≤h2≤R2 wherein R2 represents half of the width of the second protrusion portion, the width of the second protrusion portion is 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.

8. The diffusion plate of claim 5, wherein, The width of the first protrusion portion and the width of the second protrusion portion satisfy the following relationship: 2R2≤R1≤3R2 wherein R1 represents half of the width of the first protrusion portion, the width of the first protrusion portion is half of the width of the cross section of the first protrusion portion in the extending direction, R2 represents the width of the second protrusion portion, and the width of the second protrusion portion is the width of the cross section of the second protrusion portion in the extending direction.

9. The diffusion plate of claim 5, wherein, The height of the first protrusion portion and the height of the second protrusion portion satisfy the following relationship: 2h2≤h1≤3h2 wherein h1 represents the height of the first protrusion portion, and h2 represents the height of the second protrusion portion.

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

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

12. A backlight module, comprising: The backlight module comprises a light source and the diffusion plate according to any one of claims 1-11, and 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 which corresponds to one or more sub-zones of the first diffusion structure layer; and in the height direction of the first protrusion and 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-zones.

13. The backlight module of claim 12, wherein, The distance between the light source and the diffusion plate satisfies the following relationship: L1=2×(h1+H)×tanθ wherein L1 represents the interval between adjacent light emitting elements; h1 represents the height of the first protrusion; H represents the interval 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.

14. The backlight module of claim 12 or 13, wherein, The backlight module comprises two diffusion plates, i.e., a first diffusion plate and a second diffusion plate, and the second diffusion plate is located on the side of the first diffusion plate away from the light source, the first diffusion structure layer of the first diffusion plate faces the light source, and the first diffusion structure layer of the second diffusion plate faces the first diffusion plate.

15. A display device, wherein, The display device comprises a display panel and the backlight module according to any one of claims 12-14, and the display panel is located on the light emitting side of the backlight module.

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