Backlight module and display equipment

Abstract

The invention provides a backlight module and display equipment. The backlight module comprises at least one light source; the light guide plate comprises a light-in surface, a light-out surface and a bottom surface opposite to the light-out surface, and the light-in surface is located on the side, facing the light source, of the light guide plate; the diffusion sheet is located on the light-emitting surface side of the light guide plate and comprises a first surface and a second surface which are oppositely arranged, and the first surface is close to the light guide plate relative to the second surface; wherein the bottom surface and / or the first surface are / is a light adjusting surface, the light adjusting surface is provided with a plurality of light adjusting units, and the light adjusting units are configured to adjust light rays so that the light emitting angle of the diffusion sheet can be within a preset range. The backlight module has the advantages of being small in light emitting angle and high in center brightness.

Description

Technical Field

[0001] The present invention relates to the field of display technology, and particularly relates to a backlight module and a display device. Background Art

[0002] With the development of electronic products, the application scenarios of display devices are gradually increasing. Different requirements for display devices are needed in different application scenarios. For example, in the head-mounted display device applied in the near-eye display field, in order to prevent the user from feeling dizzy due to smear when wearing the head-mounted display device, the head-mounted display device is required to have a relatively small luminous power. This means that for the same size and the same structure to achieve the same backlight brightness, a larger current is needed. As the current increases, the power consumption of the display device increases. Summary of the Invention

[0003] The present invention aims to at least solve one of the technical problems existing in the prior art, and provides a backlight module and a display device.

[0004] According to one aspect of the present invention, a backlight module is provided, including:

[0005] At least one light source;

[0006] A light guide plate, the light guide plate includes a light incident surface, a light emitting surface, and a bottom surface disposed opposite to the light emitting surface. The two ends opposite to the light incident surface are respectively connected to the light emitting surface and the bottom surface. The light incident surface is located on the side of the light guide plate facing the light source;

[0007] A diffusion sheet, the diffusion sheet is located on the light emitting surface side of the light guide plate. The diffusion sheet includes a first surface and a second surface disposed opposite to each other. The first surface is closer to the light guide plate than the second surface;

[0008] Wherein, the bottom surface and / or the first surface is a dimming surface, and the dimming surface has a plurality of dimming units, and the dimming units are configured to adjust light so that the light emitting angle of the diffusion sheet is within a preset range.

[0009] In some alternative embodiments, when the bottom surface is the dimming surface, the dimming units on the bottom surface are first dimming units. At least two of the plurality of first dimming units are spaced apart in the projection on a first reference plane, and at least two of the plurality of first dimming units are spaced apart in the projection on a second reference plane. Wherein, the first reference plane is perpendicular to a first direction, the second reference plane is perpendicular to a second direction, the first direction is the arrangement direction of the light source and the light guide plate, and the first direction intersects with the second direction.

[0010] In some alternative embodiments, the distribution density of the first light-dimming unit gradually increases in a direction away from the light-incident surface.

[0011] In some alternative embodiments, the maximum height of multiple first light-dimming units in the thickness direction of the light guide plate gradually increases in a direction away from the light-incident surface.

[0012] In some alternative embodiments, the first light-dimming unit has at least one adjusting surface facing the light-incident surface, and the distance from the adjusting surface to the light-emitting surface gradually decreases in a direction away from the corresponding light-incident surface.

[0013] In some alternative embodiments, the angle between the adjusting surface and the plane where the light guide plate is located is greater than or equal to 10° and less than or equal to 45°.

[0014] In some alternative embodiments, the length of the adjusting surface in the first direction is greater than or equal to 10 microns and less than or equal to 45 microns.

[0015] In some alternative embodiments, when the first surface is the light-dimming surface, the light-dimming units on the first surface are second light-dimming units, the second light-dimming units extend along a second direction, and multiple second light-dimming units are arranged at intervals along a first direction, where the first direction is the arrangement direction of the light source and the light guide plate, and the first direction intersects with the second direction.

[0016] In some alternative embodiments, the longitudinal section of the second light-dimming unit perpendicular to the second direction is a triangular structure, and the angle of the triangular structure away from the second surface is greater than or equal to 45° and less than or equal to 145°.

[0017] In some alternative embodiments, the maximum length of the second light-dimming unit in the first direction is greater than or equal to 20 microns and less than or equal to 180 microns.

[0018] In some alternative embodiments, the second surface has multiple diffusion units, and at least two of the multiple diffusion units are spaced apart in the orthographic projection on a first reference plane, and at least two of the multiple diffusion units are spaced apart in the orthographic projection on a second reference plane, where the first reference plane is perpendicular to the first direction and the second reference plane is perpendicular to the second direction.

[0019] In some alternative embodiments, the length of the diffusion unit in the first direction is greater than or equal to 10 microns and less than or equal to 100 microns.

[0020] In some alternative embodiments, the diffusion unit includes a curved surface protruding in a direction away from the first surface.

[0021] In some alternative embodiments, a plurality of light-emitting units are disposed on the light-emitting surface, the light-emitting units extend along the second direction, and the plurality of light-emitting units are arranged at intervals along the first direction.

[0022] In some alternative embodiments, the maximum height of the light-emitting unit is less than 1 micrometer.

[0023] In some alternative embodiments, the length of the light-emitting unit in the first direction is greater than or equal to 3 micrometers and less than or equal to 25 micrometers.

[0024] In some alternative embodiments, the backlight module further includes a prism assembly, and the prism assembly includes:

[0025] A first prism sheet, the first prism sheet is located on the side of the diffusion sheet away from the light guide plate, and a plurality of first prisms are provided on the surface of the first prism sheet away from the diffusion sheet, the first prisms extend along the first direction, and the plurality of first prisms are arranged at intervals along the second direction;

[0026] A second prism sheet, the second prism sheet is located on the side of the first prism sheet away from the diffusion sheet, and a plurality of second prisms are provided on the surface of the second prism sheet away from the first prism sheet, the second prisms extend along the second direction, and the plurality of second prisms are arranged at intervals along the first direction.

[0027] According to another aspect of the present invention, a display device is provided, including the above-mentioned backlight module. Description of the Drawings

[0028] The drawings are used to provide a further understanding of the present invention, and constitute a part of the specification, and are used to explain the present invention together with the following specific embodiments, but do not constitute a limitation to the present invention. In the drawings:

[0029] Figure 1 A top view of a backlight module according to an alternative embodiment of the present invention is shown;

[0030] Figure 2 Shown is Figure 1 The view taken along line A-A in

[0031] Figure 3 Shown is Figure 2 The optical path diagram inside the diffusion sheet in

[0032] Figure 4 Shown is Figure 2 The optical path diagram inside the light guide plate in

[0033] Figure 5 Shown is Figure 1 The structural schematic diagram of the light guide plate in

[0034] Figure 6 shows Figure 1 a view of another angle of the first prism in

[0035] Figure 7 shows the brightness distribution diagrams of different viewing angles at the center position of the backlight module in another alternative embodiment of the present invention;

[0036] Figure 8 shows the manufacturing flow chart of the light guide plate in another alternative embodiment of the present invention;

[0037] Figure 9 shows the schematic structural diagram of the backlight module in an example;

[0038] Figure 10 shows Figure 9 the light path diagram inside the diffusion sheet in

[0039] Figure 11 shows Figure 9 the brightness distribution diagrams of different viewing angles at the center position of the backlight module in

[0040] 10. Light source; 20. Light guide plate; 21. Light incident surface; 22. Light exit surface; 221. Light exit unit; 23. Bottom surface; 30. Diffusion sheet; 31. First surface; 32. Second surface; 321. Diffusion unit; 40. First light-dimming surface; 41. First light-dimming unit; 411. Adjusting surface; 50. Second light-dimming surface; 51. Second light-dimming unit; 60. Prism assembly; 61. First prism sheet; 611. First prism; 62. Second prism sheet; 621. Second prism; 70. Reflector; 80. Primary template; 90. Secondary template; 100. Lower mold core; 110. Upper mold core. Detailed Embodiments

[0041] The following will describe in detail the specific embodiments of the present invention with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only for the purpose of illustration and explanation of the present invention, and are not used to limit the present invention.

[0042] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the described embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0043] Unless otherwise defined, the technical terms or scientific terms used in the embodiments of the present invention shall have the ordinary meanings as understood by those of ordinary skill in the art to which the present invention pertains. The "first", "second" and similar terms used in the present invention do not denote any order, quantity or importance, but are only used to distinguish different components. Similarly, words such as "comprising" or "including" mean that the elements or objects appearing before this word cover the elements or objects listed after this word and their equivalents, without excluding other elements or objects. The terms such as "connected" or "coupled" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The terms such as "upper", "lower", "left" and "right" are only used to represent relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0044] As used herein, "parallel" and "perpendicular" include the stated situations and situations similar to the stated situations, and the range of the similar situations is within an acceptable deviation range, where the acceptable deviation range is determined by those of ordinary skill in the art considering the measurements being discussed and the errors associated with the measurements of specific quantities (i.e., the limitations of the measurement system). For example, "parallel" includes absolute parallelism and approximate parallelism, where the acceptable deviation range for approximate parallelism can be, for example, within 5° deviation; "perpendicular" includes absolute perpendicularity and approximate perpendicularity, where the acceptable deviation range for approximate perpendicularity can also be, for example, within 5° deviation.

[0045] It should be understood that when a layer or element is referred to as being on another layer or substrate, it can be that the layer or element is directly on the other layer or substrate, or there can be an intermediate layer between the layer or element and the other layer or substrate.

[0046] Exemplary embodiments are described herein with reference to cross-sectional views and / or plan views that are idealized exemplary drawings. In the drawings, the thickness of layers and regions is exaggerated for clarity. Accordingly, variations in shape relative to the drawings due to, for example, manufacturing techniques and / or tolerances are contemplated. Thus, exemplary embodiments should not be construed as limited to the shapes of the regions shown herein, but include shape deviations due to, for example, manufacturing. Thus, the regions shown in the drawings are schematic in nature, and their shapes are not intended to show the actual shape of the regions of the device and are not intended to limit the scope of the exemplary embodiments.

[0047] Figure 1 A top view schematic diagram of a backlight module in an embodiment of the present invention is shown. Figure 2 Shown is Figure 1 the view along line A-A in Figure 1 and Figure 2As can be seen, the backlight module includes at least one light source 10, a light guide plate 20, and a diffusion sheet 30. The light guide plate 20 includes a light incident surface 21, a light exit surface 22, and a bottom surface 23 disposed opposite to the light exit surface 22. The light incident surface 21 is located on the side of the light guide plate 20 facing the light source 10. The light incident surface 21 is connected to both the light exit surface 22 and the bottom surface 23, so that the light emitted by the light source 10 enters the light guide plate 20 from one side, forming a side-entry backlight module. After the light enters the light guide plate 20, part of the light is reflected multiple times between the light exit surface 22 and the bottom surface 23 and then exits through the light exit surface 22, and another part of the light is directly reflected by the bottom surface 23 to the light exit surface 22 and exits. The light exiting from the light guide plate 20 enters the diffusion sheet 30.

[0048] When there are multiple light sources 10, the light guide plate 20 has multiple light incident surfaces 21, and each light source 10 corresponds to one light incident surface 21. Please refer to Figure 2 . For example, when there are two light sources 10, the two light sources 10 are respectively located on opposite sides of the light guide plate 20, then there are two light incident surfaces 21, and the two light incident surfaces 21 are respectively located on opposite sides of the light exit surface 22 and the bottom surface 23, so that the light emitted by each light source 10 enters the interior of the light guide plate 20 through the corresponding light incident surface 21.

[0049] In Figure 2 In the specific embodiment shown, the diffusion sheet 30 is located on the light exit side of the light guide plate 20. The diffusion sheet 30 includes a first surface 31 and a second surface 32 disposed opposite to each other. The first surface 31 is closer to the light guide plate 20 than the second surface 32; the bottom surface 23 and the first surface 31 are light-adjusting surfaces, and the light-adjusting surfaces have multiple light-adjusting units configured to adjust the light, so that the light exit angle of the diffusion sheet 30 is within a preset range. By providing multiple light-adjusting units on the light-adjusting surface, the light-adjusting units adjust the light, so that the light exiting from the diffusion sheet 30 is concentrated within a preset angle range, thereby improving the light exit brightness. Such a setting improves the light exit brightness of the backlight module under the same current, achieving the purpose of reducing the power consumption of the backlight module.

[0050] It should be noted that the function of the diffusion sheet 30 is not to spread the light in a large-angle direction, but to homogenize the light and can adjust the light at the same time, so that the light is evenly distributed within a preset angle range.

[0051] In some alternative embodiments, only the bottom surface 23 is the light-adjusting surface, and the diffusion sheet 30 does not have a light-adjusting surface. The light-adjusting surface can adjust the light, so that the light exiting from the diffusion sheet 30 is concentrated within a preset angle range, achieving the effect of improving the light exit brightness. For example, when the bottom surface 23 is the adjusting surface, the light exiting from the light guide plate 20 is concentrated within a preset angle range, and the diffusion sheet 30 can only homogenize the light and does not have an adjusting function, as long as it is ensured that the light exiting from the diffusion sheet 30 is still concentrated within a preset angle range.

[0052] In some other alternative embodiments, only the first surface 31 is a dimming surface, and the light guide plate 20 does not have a dimming surface, which can adjust the light so that the light emitted from the diffusion sheet 30 is concentrated within a preset angular range, achieving the effect of improving the light-emitting brightness.

[0053] In Figure 2 In the specific embodiment shown, both the bottom surface 23 and the first surface 31 are dimming surfaces. When the light irradiates the dimming unit on the bottom surface 23, the dimming unit on the bottom surface 23 preliminarily adjusts the light to reduce the light-emitting angle of the light. After the light is transmitted from the light guide plate 20 to the diffusion sheet 30, the dimming unit on the diffusion sheet 30 adjusts the light again. After the light is adjusted twice by the light guide plate 20 and the diffusion sheet 30, the light emitted from the diffusion sheet 30 is concentrated within a preset angular range, which is beneficial to improving the light-emitting brightness of the backlight module.

[0054] It should be noted that although the bottom surface 23 can be a dimming surface and the first surface 31 can also be a dimming surface, the specific structures of the dimming units on the dimming surfaces of different structures are different. For example, when the bottom surface 23 is a dimming surface, the dimming unit is a two-dimensional structure. When the first surface 31 is a dimming surface, the dimming unit is a one-dimensional structure. Among them, the two-dimensional structure means that the dimming units are arranged in two directions, or have periodicity in two dimensions, while the one-dimensional structure means that the dimming units are arranged in one direction, or have periodicity in one dimension.

[0055] In some alternative embodiments, please refer to Figure 2 and Figure 4 , when the bottom surface 23 is a dimming surface, the bottom surface 23 is the first dimming surface 40, and the first dimming surface 40 has a plurality of first dimming units 41. At least two of the plurality of first dimming units 41 are spaced apart in the projection on the first reference plane, and at least two of the plurality of first dimming units 41 are spaced apart in the projection on the second reference plane. Among them, the first reference plane is perpendicular to the first direction, the second reference plane is perpendicular to the second direction, the first direction is the arrangement direction of the light source 10 and the light guide plate 20, and the first direction intersects the second direction. Or rather, the plurality of first dimming units 41 are divided into multiple rows of first dimming groups, and the multiple rows of first dimming groups are spaced apart along the first direction. And there is at least one first dimming unit in the first dimming group. When there is only one first dimming unit in each first dimming group, at least two first dimming units are not aligned in the first direction, so that at least two first dimming units are arranged in the second direction. If there are multiple first dimming units in at least one first dimming group, and the multiple first dimming units in the first dimming group are spaced apart along the second direction.

[0056] It should be noted that the first direction is the X direction and the second direction is the Y direction.

[0057] In some alternative embodiments, the distribution density of the first light-dimming unit 41 gradually increases in a direction away from the light-incident surface 21. The light intensity in the region of the light guide plate 20 close to the light-incident surface 21 is greater than that in the region away from the light-incident surface 21. The distribution density of the first light-dimming unit 41 is small in the region close to the light-incident surface 21 to ensure the light intensity transmitted to the region away from the light-incident surface 21, which is conducive to the uniform distribution of the light intensity of the light emitted from the light-emitting surface 22 and reduces the situation where the light intensity in some regions on the light-emitting surface 22 is too strong while the light intensity in other regions is weak.

[0058] It should be noted that when there is one light source 10, only one side of the light guide plate 20 has a light-incident surface 21. At this time, the distribution density of the first light-dimming unit 41 in the entire light guide plate 20 gradually increases in a direction away from the light-incident surface 21. If there are two light sources 10 and the two light sources 10 are located on opposite sides of the light guide plate 20, the distribution density of the first light-dimming unit 41 gradually increases from the two light-incident surfaces 21 in a direction towards the center of the light guide plate 20.

[0059] In some alternative embodiments, the maximum height of the plurality of first light-dimming units 41 in the thickness direction of the light guide plate 20 gradually increases in a direction away from the light-incident surface 21. The light intensity in the region of the light guide plate 20 close to the light-incident surface 21 is greater than that in the region away from the light-incident surface 21. The maximum height of the first light-dimming unit 41 in the region close to the light-incident surface 21 in a plane perpendicular to the plane where the light guide plate 20 is located is small, which can reduce the light intensity reflected to the light-emitting surface 22 to ensure the light intensity transmitted to the region away from the light-incident surface 21, which is conducive to the uniform distribution of the light intensity of the light emitted from the light-emitting surface 22.

[0060] It should be noted that when there is one light source 10, only one side of the light guide plate 20 has a light-incident surface 21. At this time, the maximum height of the plurality of first light-dimming units 41 in the thickness direction of the entire light guide plate 20 gradually increases in a direction away from the light-incident surface 21. If there are two light sources 10 and the two light sources 10 are located on opposite sides of the light guide plate 20, the maximum height of the first light-dimming unit 41 in the thickness direction of the light guide plate 20 gradually increases from the two light-incident surfaces 21 in a direction towards the center of the light guide plate 20.

[0061] In some alternative embodiments, please refer to Figure 2 , the first light-dimming unit 41 has at least one adjusting surface 411 facing the light-incident surface 21, and the distance from the adjusting surface 411 to the light-emitting surface 22 gradually decreases in a direction away from the corresponding light-incident surface 21. The adjusting surface 411 is an inclined plane, which is conducive to reflecting the light to the light-emitting surface 22 so that the light is emitted from the light-emitting surface 22.

[0062] It should be noted that when the light guide plate 20 has an incident light surface 21, the first light regulating unit 41 has a regulating surface 411. When the light guide plate 20 has two incident light surfaces 21, the two incident light surfaces 21 are located on opposite sides of the light guide plate 20. For example, the two incident light surfaces 21 are the first incident light surface and the second incident light surface respectively. The first light regulating unit 41 may only have one regulating surface 411. The regulating surfaces 411 on the plurality of first light regulating units 41 close to the first incident light surface face the first incident light surface, and the regulating surfaces 411 on the plurality of first light regulating units 41 close to the second incident light surface face the second incident light surface; it may also be that each first light regulating unit 41 has two regulating surfaces 411, and the two regulating surfaces 411 are arranged to face the two incident light surfaces 21. The corresponding relationship between the regulating surface 411 and the incident light surface 21 on the first light regulating unit 41 is not specifically limited here, as long as it is ensured that the first light regulating unit 41 has at least one regulating surface 411 facing the incident light surface 21.

[0063] In some alternative embodiments, the maximum height of the regulating surfaces 411 on the plurality of first light regulating units 41 gradually increases in a direction away from the incident light surface 21, which is beneficial to ensuring the uniformity of the light emitted from the light emitting surface 22. When a first light regulating unit 41 has a plurality of regulating surfaces 411, the maximum heights of the plurality of regulating surfaces 411 are the same, and it is only necessary to ensure that the maximum height of the first light regulating unit 41 satisfies the trend of gradually increasing in a direction away from the incident light surface 21.

[0064] Optionally, the maximum height of the regulating surface 411 is the maximum height of the first light regulating unit 41.

[0065] In some alternative embodiments, the first light regulating unit 41 is in the shape of a quadrangular pyramid.

[0066] In some alternative embodiments, the angle between the regulating surface 411 and the plane where the light guide plate 20 is located is greater than or equal to 10° and less than or equal to 45°. When the angle between the regulating surface 411 and the plane where the light guide plate 20 is located is less than 10°, it is not conducive to the light entering the regulating surface 411. When the angle between the regulating surface 411 and the plane where the light guide plate 20 is located is greater than 45°, it is not conducive to the regulating surface 411 reflecting the light to the light emitting surface 22. Limiting the angle between the regulating surface 411 and the plane where the light guide plate 20 is located within the range of 10° to 45° is beneficial to the regulating surface 411 receiving the light and reflecting the light to the light emitting surface 22.

[0067] In some alternative embodiments, there is an adjusting surface 411 on the first dimming unit 41. In the technical solution where the maximum height of the adjusting surfaces 411 on multiple first dimming units 41 gradually increases in a direction away from the light incident surface 21, there can be various forms. For example, if the angles between multiple adjusting surfaces 411 and the plane where the light guide plate 20 is located are the same, then the widths of multiple adjusting surfaces 411 in the first direction gradually increase in a direction away from the light incident surface 21. Another example is that if the widths of multiple adjusting surfaces 411 in the first direction are the same, then the angles between multiple adjusting surfaces 411 and the plane where the light guide plate 20 is located gradually increase. It can also be that the widths of multiple adjusting surfaces 411 in the first direction and the angles between multiple adjusting surfaces 411 and the plane where the light guide plate 20 is located are all different, and no specific limitation is made here.

[0068] In some alternative embodiments, the length of the adjusting surface 411 in the first direction is greater than or equal to 10 micrometers and less than or equal to 45 micrometers. The length of the adjusting surface 411 in the first direction refers to the length of the positive projection of the adjusting surface 411 on the plane where the light guide plate 20 is located in the first direction. By limiting the length of the adjusting surface 411 in the first direction, it is beneficial to control the maximum height of the adjusting surface 411 within a reasonable range, which is beneficial to ensuring the lateral transmission of light in the light guide plate 20 while adjusting the light.

[0069] In some alternative embodiments, when the first surface 31 is a dimming surface, the first surface 31 is the second dimming surface 50. The second dimming surface 50 has multiple second dimming units 51. The second dimming units 51 extend along the second direction, and multiple second dimming units 51 are arranged at intervals along the first direction. Among them, the first direction is the arrangement direction of the light source 10 and the light guide plate 20, and the first direction intersects with the second direction. That is to say, the second dimming unit 51 is a strip-shaped structure, and the strip-shaped structures are arranged along the same direction. By providing multiple second dimming units 51 on the first surface 31, it is beneficial to control the light output angle of the diffusion sheet 30 within a preset angle range and improve the light output intensity.

[0070] In some alternative embodiments, please refer to Figure 2 , the second dimming unit 51 protrudes in a direction away from the second surface 32, and the longitudinal section of the second dimming unit 51 perpendicular to the second direction is a triangular structure. The angle of the triangular structure away from the second surface 32 is greater than or equal to 45° and less than or equal to 145°. Limiting the angle of the triangular structure away from the second surface 32 within the range of 45° to 145° is beneficial to the smooth entry of light into the diffusion sheet 30, reducing the reflection by the second dimming unit 51, and effectively reducing the loss of light energy.

[0071] In some alternative embodiments, the maximum length of the second dimming unit 51 in the first direction is greater than or equal to 20 microns and less than or equal to 180 microns. Controlling the maximum length of the second dimming unit 51 within the range of 20 microns to 180 microns is beneficial to ensuring the distribution density of the second dimming unit 51, while reducing the manufacturing difficulty of the diffuser 30 when narrowing the light-emitting angle.

[0072] In some alternative embodiments, the second surface 32 has a plurality of diffusion units 321. At least two of the plurality of diffusion units 321 are spaced apart in the orthographic projection on the first reference plane, and at least two of the plurality of diffusion units 321 are spaced apart in the orthographic projection on the second reference plane, where the first reference plane is perpendicular to the first direction and the second reference plane is perpendicular to the second direction. That is to say, the diffusion unit 321 is a two-dimensional structure. Or, the plurality of diffusion units 321 are divided into multiple rows of diffusion groups, and the multiple rows of diffusion groups are spaced apart along the first direction, and there is at least one diffusion unit 321 in the diffusion group. When there is only one diffusion unit 321 in each diffusion group, at least two diffusion units 321 are not aligned in the first direction, so that at least two diffusion units 321 are arranged in the second direction. If there are multiple diffusion units 321 in at least one diffusion group, the multiple diffusion units 321 in the diffusion group are spaced apart along the second direction.

[0073] By providing a plurality of diffusion units 321 on the second surface 32, it is beneficial to the uniform distribution of light, avoiding the situation where the light intensity is strong in some areas and weak in other areas, so that the light emitted from the diffuser 30 is uniformly distributed within a preset angle.

[0074] In some alternative embodiments, the length of the diffusion unit 321 in the first direction is greater than or equal to 10 microns and less than or equal to 100 microns. Such a setting can ensure the light homogenization effect of the diffusion unit 321 while avoiding increasing the manufacturing difficulty of the diffuser 30.

[0075] In Figure 2 and Figure 3 In the specific embodiment shown, the diffusion unit 321 includes a curved surface protruding away from the first surface 31. Or, the diffusion unit 321 is a protrusion provided on the second surface 32, and is a semi-circular or elliptical protrusion.

[0076] In some alternative embodiments, please refer to Figure 5, a plurality of light-emitting units 221 are provided on the light-emitting surface 22. The light-emitting units 221 are configured to couple out the light in the light guide plate 20. The light-emitting units 221 extend in the second direction, and the plurality of light-emitting units 221 are arranged at intervals in the first direction. By providing the plurality of light-emitting units 221 on the light-emitting surface 22, on the one hand, it can play a role in uniforming the light, which is beneficial to the uniform distribution of the light. On the other hand, the extending direction of the light-emitting unit 221 is parallel to the extending direction of the second dimming unit 51, and the light-emitting unit 221 and the second dimming unit 51 cooperate to further reduce the light-emitting angle of the diffusion sheet 30.

[0077] In some alternative embodiments, the maximum height of the light-emitting unit 221 is less than 1 micron. Such a setting ensures the light homogenization effect while ensuring the thickness of the light guide plate 20, which is beneficial to the thinning of the backlight module.

[0078] In some alternative embodiments, the length of the light-emitting unit 221 in the first direction is greater than or equal to 3 microns and less than or equal to 25 microns. Such a setting can ensure the light homogenization effect of the light-emitting unit 221 and reduce the waste of light energy.

[0079] In some alternative embodiments, please refer to Figure 2 and Figure 6 , the backlight module further includes a prism assembly 60. The prism assembly 60 includes a first prism sheet 61 and a second prism sheet 62. The first prism sheet 61 is located on the side of the diffusion sheet 30 away from the light guide plate 20. The surface of the first prism sheet 61 away from the diffusion sheet 30 has a plurality of first prisms 611. The first prisms 611 extend in the first direction, and the plurality of first prisms 611 are arranged at intervals in the second direction; the second prism sheet 62 is located on the side of the first prism sheet 61 away from the diffusion sheet 30. The surface of the second prism sheet 62 away from the first prism sheet 61 has a plurality of second prisms 621. The second prisms 621 extend in the second direction, and the plurality of second prisms 621 are arranged at intervals in the first direction. By providing the prism assembly 60, the light can be further concentrated, and the light-emitting angle of the backlight module can be reduced. In addition, by making the extending direction of the first prism 611 cross the extending direction of the second dimming unit 51 and the extending direction of the second prism 621 parallel to the extending direction of the second dimming unit 51, the light-emitting angle of the prism assembly 60 can be reduced, and the light-emitting angle of the backlight module can be further reduced, which is beneficial to the more concentrated light intensity of the backlight module.

[0080] In some alternative embodiments, please refer to Figure 2 , the backlight module further includes a reflector 70. The reflector 70 is located on the side of the light guide plate 20 away from the diffusion sheet 30 to reflect the light emitted from the bottom surface 23 of the light guide plate 20 back into the light guide plate 20 to reduce the loss of light energy.

[0081] In the present invention, due to the structural design on the first surface 31 and the second surface 32 of the diffusion sheet 30, with the first surface 31 being the light-adjusting surface and the second surface 32 having multiple diffusion units 321, the light output from the light guide plate 20 can be adjusted to a preset angular range. The light within this range can be further adjusted to near 0° after passing through the first prism sheet 61 and the second prism sheet 62, so that the light-emitting angle of the backlight module is greater than or equal to -5° and less than or equal to 5°, enabling more of the light output by the backlight module to be concentrated within -5° to 5°, achieving the effect of brightness improvement. For example, the light-emitting angle of the backlight module is greater than or equal to -2° and less than or equal to 2°.

[0082] Figure 9 The light-emitting uniformity of the backlight module shown in [reference] is 81.9%, and the half-peak width of the viewing angle is 46.7°. If Figure 10 the relative central brightness of the backlight module shown in [reference] is 100%, please refer to Figure 11 , then for the backlight module in an optional embodiment of the present invention, for example, when the light-emitting angle of the diffusion sheet 30 is within the range of 50° to 60°, the light-emitting uniformity of the backlight module is 86.6%, the half-peak width of the viewing angle is 49.1°, and the relative central brightness of the backlight module is 144%. Please refer to Figure 7 . It can be seen from this that the central brightness of the backlight module in the present application is increased by 44% and the uniformity is increased by 5.7% compared to the backlight module exemplified in Figure 9 , while the viewing angle is basically the same.

[0083] In addition, from Figure 10 which is Figure 9 the optical path diagram inside the diffusion sheet in [reference], Figure 3 shows Figure 2 the optical path diagram inside the diffusion sheet in [reference]. From the comparison between Figure 10 and Figure 3 , it can be seen that Figure 3 the light-emitting angle of the diffusion sheet 30 in [reference] becomes smaller and is concentrated within a preset angular range, for example, concentrated within the range of 40° to 75°, or for example, concentrated within the range of 45° to 70°, or for example, concentrated within the range of 50° to 60°.

[0084] It should be noted that when the refractive index of the first prism base layer in the first prism sheet 61 and the refractive index of the second prism base layer in the second prism sheet 62 are in the range of 1.45 to 1.65, and the refractive index of the first prism 611 and the second prism 621 are in the range of 1.57 to 1.77, the peak brightness at the center position of the backlight module shows a trend of first increasing and then decreasing with the light-emitting angle of the diffusion sheet 30. The peak brightness reaches the maximum at 50° to 60°, and reaches half of the maximum peak brightness at 40° and 75°. At 80° to 85°, the peak brightness at the center position of the backlight module drops sharply to a position that is 10% of the maximum peak brightness. And Figure 9 Most of the light-emitting angles of the diffusion sheet 30 of the backlight module shown are concentrated in the range of 80° to 85°. The light-emitting angle of the diffusion sheet 30 of the backlight module shown in the present invention is in the range of 40° and 75°, effectively improving the brightness at the center position.

[0085] For example, the refractive index of the first prism base layer and the second prism base layer is 1.55. For another example, the refractive index of the first prism 611 and the second prism 621 is 1.67.

[0086] Optionally, the light-emitting angle of the diffusion sheet 30 is in the range of 40° and 75°.

[0087] When the diffusion sheet 30 is in the range of 40° to 85°, the central viewing angle of the light emitted by the backlight module is less than 20°. It can be seen that by limiting the light-emitting angle of the diffusion sheet 30 to the range of 40° and 75°, the brightness at the center position is improved while keeping the central viewing angle of the backlight module unchanged.

[0088] It should be noted that the angles of the light rays are all the angles between the light rays and the axis perpendicular to the plane where the light guide plate 20 is located.

[0089] The light guide plate 20 of the present invention can be formed by various process methods such as injection molding and hot pressing, and the mold core can be formed by various process methods such as laser, photolithography, and dot punching. Figure 8 As an example of the process flow of the photolithographed mold core and injection-molded light guide plate, its main processes include photolithography, coating, electroplating, transfer printing, lamination, and injection molding. Specifically: a primary template 80 is formed by photolithography, a secondary template 90 is formed after coating a corrosion-resistant material on the primary template 80, and then the secondary template 90 is electroplated to form a metal film on the secondary template 90. The secondary template 90 and the metal film are separated, and a lower mold core 100 is formed on the back of the metal film. The lower mold core 100 is laminated with an upper mold core 110 to form an injection mold, and then the light guide plate 20 is formed in the injection mold.

[0090] In some alternative embodiments, the diffusion sheet 30 is a single-layer optical film layer. The optical film layer can be formed by embossing.

[0091] According to another aspect of the present invention, a display device is provided, including the above-mentioned backlight module. The display device having the above-mentioned backlight module has the advantages of high light efficiency and low power consumption. For example, the display device is a head-mounted display device.

[0092] It can be understood that the above embodiments are merely exemplary embodiments adopted to illustrate the principle of the present invention. However, the present invention is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also regarded as the protection scope of the present invention.

Claims

1. A backlight module, characterized in that: Comprising: At least one light source; A light guide plate, the light guide plate comprising a light incident surface, a light exit surface, and a bottom surface disposed opposite to the light exit surface, two opposite ends of the light incident surface being respectively connected to the light exit surface and the bottom surface, the light incident surface being located on a side of the light guide plate facing the light source; A diffusion sheet, the diffusion sheet being located on a side of the light exit surface of the light guide plate, the diffusion sheet comprising a first surface and a second surface disposed opposite to each other, the first surface being closer to the light guide plate than the second surface; Wherein, the bottom surface and / or the first surface is a dimming surface, the dimming surface having a plurality of dimming units configured to adjust light so that the light exit angle of the diffusion sheet is within a preset range.

2. The backlight module according to claim 1, wherein: When the bottom surface is the dimming surface, the dimming units on the bottom surface are first dimming units, at least two of the plurality of first dimming units being spaced apart in projection on a first reference plane, and at least two of the plurality of first dimming units being spaced apart in projection on a second reference plane, wherein the first reference plane is perpendicular to a first direction, the second reference plane is perpendicular to a second direction, the first direction is the arrangement direction of the light source and the light guide plate, and the first direction intersects the second direction.

3. The backlight module according to claim 2, wherein The distribution density of the first dimming units gradually increases in a direction away from the light incident surface.

4. The backlight module according to claim 2, wherein The maximum height of the plurality of first dimming units in the thickness direction of the light guide plate gradually increases in a direction away from the light incident surface.

5. The backlight module according to claim 2, wherein The first dimming unit has at least one adjustment surface facing the light incident surface, the distance from the adjustment surface to the light exit surface gradually decreasing in a direction away from the corresponding light incident surface.

6. The backlight module according to claim 5, wherein The angle between the adjustment surface and the plane where the light guide plate is located is greater than or equal to 10° and less than or equal to 45°.

7. The backlight module according to claim 5, characterized in that The length of the adjustment surface in the first direction is greater than or equal to 10 microns and less than or equal to 45 microns.

8. The backlight module according to any one of claims 1 to 7, characterized in that, When the first surface is the dimming surface, the dimming units on the first surface are second dimming units, the second dimming units extending along a second direction, and the plurality of second dimming units being spaced apart along a first direction, wherein the first direction is the arrangement direction of the light source and the light guide plate, and the first direction intersects the second direction.

9. The backlight module according to claim 8, wherein, The longitudinal cross-section of the second dimming unit perpendicular to the second direction is a triangular structure, and the angle of the triangular structure away from the second surface is greater than or equal to 45° and less than or equal to 145°.

10. The backlight module according to claim 8, wherein: The maximum length of the second dimming unit in the first direction is greater than or equal to 20 microns and less than or equal to 180 microns.

11. The backlight module according to claim 8, characterized in that, The second surface has a plurality of diffusion units, at least two of the plurality of diffusion units being spaced apart in the positive projection on a first reference plane, and at least two of the plurality of diffusion units being spaced apart in the positive projection on a second reference plane, wherein the first reference plane is perpendicular to a first direction, and the second reference plane is perpendicular to a second direction.

12. The backlight module according to claim 11, wherein The length of the diffusion unit in the first direction is greater than or equal to 10 microns and less than or equal to 100 microns.

13. The backlight module according to claim 11, wherein, The diffusion unit includes a cambered surface protruding away from the first surface.

14. The backlight module according to claim 8, wherein A plurality of light-emitting units are disposed on the light-emitting surface, the light-emitting units extend along the second direction, and the plurality of light-emitting units are arranged at intervals along the first direction.

15. The backlight module according to claim 14, wherein The maximum height of the light-emitting unit is less than 1 micron.

16. The backlight module according to claim 14, wherein, The length of the light-emitting unit in the first direction is greater than or equal to 3 microns and less than or equal to 25 microns.

17. The backlight module according to any one of claims 1 to 16, characterized in that, The backlight module further includes a prism assembly, and the prism assembly includes: A first prism sheet, the first prism sheet is located on a side of the diffusion sheet away from the light guide plate, and a plurality of first prisms are provided on a surface of the first prism sheet away from the diffusion sheet, the first prisms extend along the first direction, and the plurality of first prisms are arranged at intervals along the second direction; A second prism sheet, the second prism sheet is located on a side of the first prism sheet away from the diffusion sheet, and a plurality of second prisms are provided on a surface of the second prism sheet away from the first prism sheet, the second prisms extend along the second direction, and the plurality of second prisms are arranged at intervals along the first direction.

18. A display device, characterized in that, Including the backlight module according to any one of claims 1 to 17.

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