Backlight module and display device
By employing a microstructure layer and reflective dot structure in the Mini LED backlight module for light diffusion, the issues of thickness and power consumption were resolved, resulting in higher luminous efficiency and uniformity.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- BOE TECHNOLOGY GROUP CO LTD
- Filing Date
- 2025-01-20
- Publication Date
- 2026-07-23
AI Technical Summary
In the process of reducing thickness, existing Mini LED backlight modules suffer from warping issues that affect strength, flatness, and reliability. At the same time, the backlight power consumption is high, making it difficult to achieve high luminous efficiency.
The light diffusion design employs a microstructure layer and a reflective dot structure. The protrusions of the microstructure layer are arranged parallel to the line connecting the center of the light-emitting element, while the reflective dot structure absorbs and reflects light, reducing the use of a uniform light film to improve light uniformity and reduce thickness.
Without compromising strength and reliability, the thickness of the backlight module was reduced, luminous efficiency was improved, power consumption was reduced, and light uniformity was enhanced.
Smart Images
Figure CN2025073314_23072026_PF_FP_ABST
Abstract
Description
A backlight module and display device Technical Field
[0001] This disclosure relates to the field of display technology, and in particular to a backlight module and display device. Background Technology
[0002] Today, there is an increasing variety of display devices with screens, such as televisions, desktop computers, laptops, mobile phones, and e-readers. These consumer electronics products with displays are becoming increasingly integrated into people's work and daily lives. Currently, popular display technologies include LCD, OLED, Mini LED, and Micro LED. Compared to traditional LCD and OLED display technologies, Mini LED technology offers superior performance in several aspects, including image quality, high brightness, lifespan, and reliability. As a rising star in display technology, both now and in the future, Mini LED technology undoubtedly better meets users' high demands for display products and has successfully positioned itself at the forefront of the panel industry.
[0003] Mini LED BLU (backlighting unit) technology is renowned for its ability to easily achieve ultra-high brightness. Currently, Mini LED displays can effortlessly surpass 1000 nits in brightness, fully demonstrating its superiority. Compared to the edge-lit backlighting used in traditional LCD displays, Mini LED BLU offers clear advantages in resolution, contrast ratio, and energy consumption. Summary of the Invention
[0004] This disclosure provides a backlight module and a display device, the specific solutions of which are as follows:
[0005] This disclosure provides a backlight module, comprising:
[0006] A light-emitting substrate includes a substrate and a plurality of light-emitting elements disposed on one side of the substrate, wherein the light-emitting elements are Mini LEDs;
[0007] A light diffusion structure includes: a substrate layer located on the light-emitting side of the light-emitting substrate, a microstructure layer located on the side of the substrate layer closer to the light-emitting substrate, and a plurality of reflective dot structures located on the side of the substrate layer away from the light-emitting substrate; wherein, the microstructure layer has a plurality of protrusions on the side closer to the light-emitting substrate, the cross-sectional area of the protrusions gradually increases in the direction away from the light-emitting substrate, and the arrangement direction of the protrusions is parallel to the line connecting the centers of the two adjacent light-emitting elements with the largest distance.
[0008] A light guide structure is located on the side of the light diffusion structure away from the light-emitting substrate.
[0009] In one possible implementation, in the backlight module provided in the embodiments of this disclosure, the plurality of light-emitting elements are arranged in a row and column array on the substrate, and the angle between the arrangement direction of the protrusions and the row direction is 40 to 50°.
[0010] In one possible implementation, in the backlight module provided in the embodiments of this disclosure, the height of the protrusion is 10-50 μm, the bottom surface size of the protrusion is 20-100 μm, and the gap width between two adjacent protrusions near the bottom surface of the substrate layer is 0-100 μm.
[0011] In one possible implementation, in the backlight module provided in the embodiments of this disclosure, the protrusion is in the shape of a pyramid, with the vertex of the pyramid facing the side of the light-emitting substrate, and the angle between the vertical line from the vertex to the side of the pyramid and the vertical line from the vertex to the bottom of the pyramid is 45 to 60°.
[0012] In one possible implementation, in the backlight module provided in the embodiments of this disclosure, the edge of the base of the pyramid includes a straight line segment and an arc segment.
[0013] In one possible implementation, in the backlight module provided in the embodiments of this disclosure, the protrusion includes a first sub-protrusion and a second sub-protrusion stacked together. The first sub-protrusion is close to the substrate layer, and the second sub-protrusion is close to the light-emitting substrate. The first sub-protrusion is shaped like a frustum, and the second sub-protrusion is shaped like a pyramid or an arc-shaped sphere. The bottom surface of the second sub-protrusion away from the light-emitting substrate coincides with the top surface of the first sub-protrusion close to the light-emitting substrate.
[0014] In one possible implementation, in the backlight module provided in the embodiments of this disclosure, the angle between the height line of the frustum and the side height line of the frustum is 45 to 60°.
[0015] In one possible implementation, in the backlight module provided in the embodiments of this disclosure, the angle between the side surface and the bottom surface of the pyramid is smaller than the angle between the side surface and the bottom surface of the frustum.
[0016] In one possible implementation, in the backlight module provided in the embodiments of this disclosure, the material of the reflective dot structure is ink, the thickness of the reflective dot structure is 5 to 50 μm, and the reflectivity of the reflective dot structure is 40% to 85%.
[0017] In one possible implementation, in the backlight module provided in the embodiments of this disclosure, the reflective dot structure corresponds one-to-one with the light-emitting element, and the alignment accuracy between the center of the light-emitting element and the center of the reflective dot structure is less than or equal to 0.2 mm.
[0018] In one possible implementation, in the backlight module provided in the embodiments of this disclosure, each of the reflective dot structures includes multiple dots, and the size of the dots gradually decreases from the center of the light-emitting element to the surrounding area.
[0019] In one possible implementation, in the backlight module provided in the embodiments of this disclosure, the reflective dot structure includes: a first dot aligned with the center of the light-emitting element, and at least one ring of second dots surrounding the first dot; the first dot and the second dot are circular in shape, the area of the first dot is larger than the area of the second dot, the number of second dots in each ring is multiple, and the number of second dots in each ring increases and the area of each second dot decreases from the center of the light-emitting element outwards.
[0020] In one possible implementation, in the backlight module provided in the embodiments of this disclosure, the reflective dot structure includes: a first dot aligned with the center of the light-emitting element, and a plurality of second dots connected to the edge of the first dot; the first dot is circular in shape, the second dots are strip-shaped, and the area of the second dots gradually decreases from the center of the light-emitting element to the surrounding area.
[0021] In one possible implementation, in the backlight module provided in the embodiments of this disclosure, the central region of the first dot is a hollowed-out region.
[0022] In one possible implementation, in the backlight module provided in the embodiments of this disclosure, the reflective dot structure includes: a plurality of closely arranged first dots aligned with the center of the light-emitting element, and a plurality of second dots arranged around the first dots; the plurality of second dots includes a plurality of first sub-dots adjacent to the periphery of each of the first dots and a plurality of second sub-dots dispersed around the periphery of the first sub-dots;
[0023] The first dot and a portion of the first sub-dots are hexagonal in shape, while the other portion of the first sub-dots and the second sub-dots are circular in shape. The area of the first dot is larger than the area of the first sub-dots, and the area of the first sub-dots is larger than the area of the second dot.
[0024] In one possible implementation, in the backlight module provided in the embodiments of this disclosure, the central region of the first sub-dot, which is hexagonal in shape, is a hollow region.
[0025] In one possible implementation, in the backlight module provided in the embodiments of this disclosure, the radius of the area where the first dot is located is h*tan(Θ / 2), where h is the distance from the first dot to the light-emitting element, and Θ is the viewing angle width when the light-emitting element's luminous brightness is half of its central luminous brightness.
[0026] In one possible implementation, in the backlight module provided in this embodiment, the area of the second dots surrounding the first dot is (r2) 2 -r1 2 )*cos 2 (θ), r1 is the distance between the center of the first halftone dot and the inner side of a circle of second halftone dots, r2 is the distance between the center of the first halftone dot and the outer side of a circle of second halftone dots, and θ is the angle between the center line of the light-emitting element along its thickness direction and the line connecting the center of the light-emitting element and the center of a circle of second halftone dots.
[0027] In one possible implementation, in the backlight module provided in the embodiments of this disclosure, the light-emitting substrate further includes: a driving chip located on the side of the substrate facing the microstructure layer, and a first protective adhesive located on the side of the driving chip facing the microstructure layer and covering the driving chip.
[0028] The light-emitting dot structure also includes a third dot, the center of which coincides with the center of the driving chip, and the area of the third dot is 0.3 to 0.5 times the area of the first protective adhesive.
[0029] In one possible implementation, in the backlight module provided in the embodiments of this disclosure, the light diffusion structure further includes a diffusion layer located between the substrate layer and the microstructure layer. The material of the diffusion layer is ink, the thickness of the diffusion layer is 5 to 100 μm, the haze of the diffusion layer is 50% to 90%, and the transmittance of the diffusion layer is 50% to 95%.
[0030] In one possible implementation, in the backlight module provided in the embodiments of this disclosure, the light-emitting substrate further includes a reflective layer located on the side of the substrate facing the microstructure layer, the reflective layer having a hollow area exposing the light-emitting element, and the light-emitting substrate further includes a second protective adhesive located on the side of the light-emitting element facing the microstructure layer, the second protective adhesive at least covering a portion of the reflective layer around the light-emitting element;
[0031] The backlight module further includes an adhesive layer that abuts between the diffusion layer and the substrate and is located around the substrate, wherein the height of the adhesive layer is greater than or equal to the sum of the heights of the second protective adhesive and the microstructure layer.
[0032] In one possible implementation, in the backlight module provided in the embodiments of this disclosure, the light guide structure includes at least one layer of a uniform light film, a color conversion film, a prism film, a reflective polarizer, and a diffusion film stacked together.
[0033] In one possible implementation, in the backlight module provided in the embodiments of this disclosure, the thickness of the light-diffusing film is 0.1 to 0.3 mm.
[0034] Accordingly, this disclosure also provides a display device, including: a backlight module as described in any of the above embodiments of this disclosure, and a display panel located on the light-emitting surface of the backlight module. Attached Figure Description
[0035] Figure 1 is a schematic diagram of a backlight module provided in an embodiment of this disclosure;
[0036] Figure 2 is a cross-sectional schematic diagram of a partial structure in Figure 1;
[0037] Figure 3 is a planar schematic diagram of the microstructure layer in Figure 1;
[0038] Figure 4 is a planar schematic diagram of the light-emitting substrate in Figure 1;
[0039] Figure 5 is a three-dimensional schematic diagram of the protrusion 221 within the dashed box EE in Figure 3;
[0040] Figure 6 is another three-dimensional schematic diagram of protrusion 221;
[0041] Figure 7 is another planar schematic diagram of the microstructure layer 22 in Figure 1;
[0042] Figure 8 is a three-dimensional schematic diagram of one of the protrusions 221 in Figure 7;
[0043] Figure 9 is another planar schematic diagram of the microstructure layer 22 in Figure 1;
[0044] Figure 10 is a three-dimensional schematic diagram of a protrusion 221 in Figure 9;
[0045] Figure 11 is another planar schematic diagram of the microstructure layer 22 in Figure 1;
[0046] Figure 12 is another planar schematic diagram of the microstructure layer 22 in Figure 1;
[0047] Figure 13 is a three-dimensional schematic diagram of a protrusion 221 in Figures 11 and 12;
[0048] Figure 14 is another three-dimensional schematic diagram of protrusion 221 in Figure 1;
[0049] Figure 15 is another three-dimensional schematic diagram of protrusion 221 in Figure 1;
[0050] Figure 16 is another planar schematic diagram of the light-emitting substrate in Figure 1;
[0051] Figure 17 is a schematic diagram of a specific structure of the reflective dot structure;
[0052] Figure 18 is a schematic diagram of another specific structure of the reflective dot structure;
[0053] Figure 19 is a schematic diagram of another specific structure of the reflective dot structure;
[0054] Figure 20 is a schematic diagram of the effect of the reflective dot structure of this disclosure in absorbing and reflecting light;
[0055] Figure 21 is a schematic diagram of the relevant dimensions of the reflective dot structure of this disclosure;
[0056] Figure 22 is a comparison of the light homogenization effect of using the light diffusion structure 2 in Figure 1 of this disclosure to homogenize the light emitted by the light-emitting element 12 and related technologies.
[0057] Figure 23 is a schematic diagram of another structure of the backlight module provided in the embodiment of this disclosure;
[0058] Figure 24 is a schematic diagram of another structure of the backlight module provided in the embodiment of this disclosure;
[0059] Figure 25 is a schematic diagram of another structure of the backlight module provided in the embodiment of this disclosure;
[0060] Figure 26 is a schematic diagram of another structure of the backlight module provided in the embodiment of this disclosure;
[0061] Figure 27 is a schematic diagram of another structure of the backlight module provided in the embodiment of this disclosure;
[0062] Figure 28 is a schematic diagram of another structure of the backlight module provided in the embodiments of this disclosure. Detailed Implementation
[0063] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. Furthermore, the embodiments and features in the embodiments of this disclosure can be combined with each other without conflict. All other embodiments obtained by those skilled in the art based on the described embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.
[0064] Unless otherwise defined, the technical or scientific terms used in this disclosure shall have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains. The terms "comprising" or "including," and similar terms as used in this disclosure, mean that an element or object preceding the term encompasses the elements or objects listed following the term and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. Terms such as "inner," "outer," "upper," and "lower" are used only to indicate relative positional relationships; these relative positional relationships may change accordingly when the absolute position of the described objects changes.
[0065] It should be noted that the dimensions and shapes of the figures in the accompanying drawings do not reflect actual scale and are intended only to illustrate the content of this disclosure. Furthermore, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout.
[0066] The revolutionary aspect of direct-lit Mini LED BLU technology lies in its ability to support more refined local dimming techniques, thereby significantly improving display quality. In related technologies, to achieve good uniformity of the BLU light source, compared to traditional edge-lit BLUs, low-end Mini LED BLUs generally employ a high OD (dispersion distance) design, with an OD value typically ranging from 1 to 20 mm, achieving high brightness uniformity. Mid-to-high-end Mini LED BLUs, however, mostly adopt a 0OD design to reduce thickness. This necessitates adding numerous films or substrates for light homogenization in the direct-lit Mini LED BLU structure. These materials still increase the overall thickness of the Mini LED BLU and reduce its luminous efficiency, thus increasing backlight power consumption.
[0067] Currently, OOD direct-lit Mini LED BLUs require a high-thickness diffuser plate (1.2–3.0 mm) and multiple uniform light-diffusing films stacked together to obtain a light source with good uniformity. To reduce the thickness of the Mini LED BLU, many manufacturers currently create a patterned ink layer with light-reflecting and light-shielding functions on top of the Mini LED light board, combined with one or more low-thickness uniform light-diffusing films to achieve a light source with good uniformity. This type of structure with a patterned ink layer is usually called PGD (glass-based diffuser plate substrate) or PDP (PC, PS, PET, etc. diffuser plate substrate). The thickness of PGD or PDP is generally 0.4–0.8 mm, and the thickness of the uniform light-diffusing film is about 0.2–0.7 mm. If the individual substrates such as PGD (or PDP) and uniform light-diffusing film are further thinned, it will bring about problems with strength, flatness, and reliability warping.
[0068] Therefore, in order to improve the luminous efficiency of the Mini LED BLU and reduce backlight power consumption without affecting the strength, flatness, and reliability warp of the Mini LED BLU, it is necessary to further reduce the thickness of the Mini LED BLU.
[0069] This disclosure provides a backlight module, as shown in Figures 1-4. Figure 1 is a cross-sectional view of the backlight module, Figure 2 is a cross-sectional view of a partial structure in Figure 1, Figure 3 is a planar view of the microstructure layer in Figure 1, and Figure 4 is a planar view of the light-emitting substrate in Figure 1. The backlight module includes:
[0070] The light-emitting substrate 1 includes a substrate 11 and a plurality of light-emitting elements 12 disposed on one side of the substrate 11, wherein the light-emitting elements 12 are Mini LEDs;
[0071] The light diffusion structure 2 includes: a substrate layer 21 located on the light-emitting side of the light-emitting substrate 1, a microstructure layer 22 located on the side of the substrate layer 21 close to the light-emitting substrate 1, and a plurality of reflective dot structures 23 located on the side of the substrate layer 21 away from the light-emitting substrate 1; wherein, the microstructure layer 22 is provided with a plurality of protrusions 221 on the side close to the light-emitting substrate 1, the cross-sectional area of the protrusions 221 gradually increases along the direction away from the light-emitting substrate 1 (arrow F1 points), and the arrangement direction of the protrusions 221 (arrow F2 points) is parallel to the center line L connecting the two adjacent light-emitting elements 12 with the largest distance.
[0072] The light guide structure 3 is located on the side of the light diffusion structure 2 away from the light-emitting substrate 1.
[0073] The backlight module provided in this embodiment of the present disclosure has a light diffusion structure composed of a microstructure layer, a substrate layer, and a reflective dot structure on the light-emitting side of the light-emitting substrate. On the one hand, the multiple protrusions of the microstructure layer can refract the light emitted by the light-emitting element to achieve uniform light distribution and optimize the uniform light effect. On the other hand, the reflective dot structure can reflect the light, and the part of the light with the strongest light intensity near the front viewing angle of the light-emitting element will also be partially absorbed by the reflective dot structure, further improving the uniform light effect. In addition, the light-emitting elements are generally arranged in an array, and the brightness difference between the two adjacent light-emitting elements with the largest distance is the largest. This disclosure sets the arrangement direction of the protrusions in the microstructure layer to be parallel to the center line connecting the two adjacent light-emitting elements with the largest distance. In this way, the direction in which the protrusions have the best light diffusion effect is consistent with the center line connecting the two adjacent light-emitting elements with the largest distance, so that the final uniform light effect is the best. Therefore, the uniformity of light emitted through the light diffusion structure in this embodiment is greatly improved. This allows for a reduction in the number or thickness of the light-diffusing film (described later) in the light guide structure without affecting the overall strength, flatness, and reliability warp of the backlight module. This reduces the overall thickness of the backlight module, thereby improving its luminous efficiency and reducing its power consumption.
[0074] In some embodiments, as shown in Figures 1 and 2, the substrate 11 of the light-emitting substrate 1 can be made of glass or a flexible material such as a PCB. The side of the substrate 11 facing the light-emitting element 12 has a conductive metal film, SiNx or SiOx insulation, OC low dielectric constant insulation layer, etc. deposited by processes such as electroplating, PVD, CVD, and Coating. Then, a driving circuit that enables the light-emitting element 12 to emit light is formed by processes such as exposure and etching. The side of the substrate 11 away from the light-emitting element 12 may be provided with a metal backplate to improve the strength of the light-emitting substrate 1.
[0075] In some embodiments, as shown in Figures 1 and 2, the light-emitting element 12 is a Mini LED as an example. The Mini LED is a PN junction containing electro-optic conversion and its required driving circuit, leads, encapsulation protection layer or other functional layers fabricated on an epitaxial wafer. The light emitted by the Mini LED can be blue light or white light.
[0076] Alternatively, the light-emitting element 12 in the embodiments of this disclosure may also be a Micro LED.
[0077] In some embodiments, as shown in Figures 1 and 2, the substrate layer 21 in the light diffusion structure 2 can be made of PC, PS, PET, etc., and the thickness of the substrate layer 21 can be 0.8 to 3 mm; the substrate layer 21 can also be made of glass, and the thickness of the glass substrate layer 21 can be thinner, for example, its thickness can be 0.3 to 1 mm.
[0078] In some embodiments, in the backlight module provided in this disclosure, as shown in FIG4, a plurality of light-emitting elements 12 are arranged in a row and column array on the substrate 11. That is, the light-emitting elements 12 are generally arranged in a horizontal (row) / vertical (column) direction or close to a horizontal (row) / vertical (column) direction. The angle β between the arrangement direction of the protrusions 221 (pointed to by arrow F2) and the row direction X is 40 to 50°, preferably β is 45°. In this way, the protrusions 221 in the microstructure layer 22 are arranged along the diagonal direction of the square formed by every four light-emitting elements 12, resulting in better light uniformity.
[0079] In some embodiments, in the backlight module provided in the present disclosure, as shown in Figures 1-3 and 5, Figure 5 is a three-dimensional schematic diagram of the protrusion 221 within the dashed frame EE in Figure 3. The shape of the protrusion 221 can be a pyramid, such as a triangular pyramid, a square pyramid, a pentagonal pyramid, a hexagonal pyramid, etc. Figure 5 takes a square pyramid as an example. The vertex A of the pyramid faces the light-emitting substrate 1. The height h of the protrusion 221 (i.e., the square pyramid) can be 10-50 μm. The bottom surface dimensions of the protrusion 221 (e.g., the bottom surface widths a and b of the square pyramid) can be 20-100 μm. The gap width s between two adjacent protrusions (i.e., the square pyramid) near the bottom surface of the substrate layer 21 can be 0-100 μm. Figure 5 takes s greater than 0 as an example. The pitch p of the microstructure layer 22 can be 20-200 μm.
[0080] In some embodiments, in the backlight module provided in this disclosure, as shown in Figures 1-3 and 5, the angle α between the vertical line B1 from vertex A of the protrusion 221 (i.e., the square pyramid) to the side surface of the pyramid and the vertical line B2 from vertex A to the base of the pyramid can be 45-60°, that is, the angle 2α between the altitudes (i.e., B1) of the two opposite sides of the square pyramid is 90°-120°. In this way, the square pyramid can mix the light emitted by the light-emitting element 12 as much as possible and avoid total reflection.
[0081] In some embodiments, in the backlight module provided in the present disclosure, as shown in Figures 1-3 and 5, the material of the microstructure layer 22 can be a transparent polymer material such as PC with a refractive index of 1.5 to 1.7, and the protrusions 221 (i.e., square pyramids) can be fabricated by nanoimprint molding.
[0082] In some embodiments, in the backlight module provided in the present disclosure, as shown in FIG6, the edges of the bottom surface of the protrusion 221 (i.e., the square pyramid) may include straight segments and arc segments. For example, one pair of edges of the bottom surface of the square pyramid are straight segments and the other pair of edges are arc segments. The uniform light effect of the square pyramid is the same as the uniform light effect of the square pyramid shown in FIG5.
[0083] In some embodiments, in the backlight module provided in the present disclosure, as shown in Figures 7 and 8, Figure 7 is another planar schematic diagram of the microstructure layer 22 in Figure 1, and Figure 8 is a three-dimensional schematic diagram of a protrusion 221 in Figure 7. The shape of the protrusion 221 can also be a triangular pyramid. The height h of the triangular pyramid can be 10 to 50 μm, the width a and b of the base of the triangular pyramid can be 20 to 100 μm, and the gap width s between two adjacent triangular pyramids near the base of the substrate layer 21 can be 0 to 100 μm. In the present disclosure embodiment, s is 0 as an example, that is, the adjacent triangular pyramids are closely connected.
[0084] In some embodiments of the backlight module provided in this disclosure, as shown in Figures 7 and 8, the angle α between the vertical line B1 from vertex A of the triangular pyramid to the side surface of the pyramid and the vertical line (i.e., height h) from vertex A to the base of the pyramid can be 45° to 60°, that is, the angle 2α between the height line (e.g., B1) of one side surface of the triangular pyramid and its opposite side (e.g., B3 in the figure) is 90° to 120°. In this way, the triangular pyramid can mix the light emitted by the light-emitting element 12 as much as possible and avoid total internal reflection.
[0085] In some embodiments, in the backlight module provided in the present disclosure, as shown in Figures 9 and 10, Figure 9 is another planar schematic diagram of the microstructure layer 22 in Figure 1, and Figure 10 is a three-dimensional schematic diagram of a protrusion 221 in Figure 9. The shape of the protrusion 221 can also be a hexagonal pyramid. The height h of the hexagonal pyramid can be 10 to 50 μm, the width a of the base surface of the hexagonal pyramid can be 20 to 100 μm, and the gap width s between two adjacent hexagonal pyramids near the base surface of the substrate layer 21 can be 0 to 100 μm. In the present disclosure embodiment, s is 0 as an example, that is, the adjacent hexagonal pyramids are closely connected.
[0086] In some embodiments, in the backlight module provided in this disclosure, as shown in Figures 9 and 10, the angle α between the vertical line B1 from vertex A of the hexagonal pyramid to a side surface and the vertical line from vertex A to the base of the pyramid (i.e., the height h) can be 45° to 60°. That is, the angle 2α between the height line of one side surface of the hexagonal pyramid (e.g., B1) and the height line of its opposite side surface (e.g., B4 in the figure) is 90° to 120°. In this way, the hexagonal pyramid can mix the light emitted by the light-emitting element 12 as much as possible and avoid total internal reflection.
[0087] In some embodiments, in the backlight module provided in the present disclosure, as shown in Figures 11-13, Figure 11 is another planar schematic diagram of the microstructure layer 22 in Figure 1, Figure 12 is another planar schematic diagram of the microstructure layer 22 in Figure 1, and Figure 13 is a three-dimensional schematic diagram of a protrusion 221 in Figures 11 and 12. The shape of the protrusion 221 can also be a cone. The height h of the cone can be 10 to 50 μm, the diameter a of the bottom surface of the cone can be 20 to 100 μm, and the gap width s between two adjacent cones near the bottom surface of the substrate layer 21 can be 0 to 100 μm. In the present disclosure embodiment, s is greater than 0, that is, adjacent cones are spaced apart.
[0088] In some embodiments, in the backlight module provided in the present disclosure, as shown in Figures 11-13, a diameter of the bottom surface of the cone and the vertex A form a triangle. The apex angle of this triangle is the cone apex angle 2α, which can be 90° to 120°. In this way, the cone can mix the light emitted by the light-emitting element 12 as much as possible without total reflection.
[0089] In some embodiments, in the backlight module provided in the present disclosure, as shown in Figures 11 and 12, the conical arrangement shown in Figure 12 is more compact than the conical arrangement in Figure 11, which can further improve the light uniformity effect.
[0090] In some embodiments, in the backlight module provided in the present disclosure, as shown in FIG14, FIG14 is another perspective view of the protrusion 221 in FIG1. The protrusion 221 includes a first sub-protrusion C1 and a second sub-protrusion C2 stacked together. The first sub-protrusion C1 is close to the substrate layer 21, and the second sub-protrusion C2 is close to the light-emitting substrate 1. The shape of the first sub-protrusion C1 is a frustum, and the shape of the second sub-protrusion C2 is a pyramid. The bottom surface of the second sub-protrusion C2 away from the light-emitting substrate 1 coincides with the top surface of the first sub-protrusion C1 close to the light-emitting substrate 1.
[0091] In some embodiments, in the backlight module provided in the present disclosure, as shown in FIG15, FIG15 is another perspective view of the protrusion 221 in FIG1. The difference between FIG15 and FIG14 is that the shape of the second sub-protrusion C2 is an arc-shaped spherical surface.
[0092] It should be noted that the shape of the protrusion 221 is ideally a pyramid, but due to the influence of the manufacturing process, it is impossible to form an ideal pyramid when making the protrusion 221. Therefore, when making the pyramidal protrusion 221, the structure shown in Figures 14 and 15 may be formed.
[0093] In some embodiments, in the backlight module provided in the present disclosure, as shown in Figures 14 and 15, taking a quadrangular truncated pyramid as an example, the angle α between the height line of the quadrangular truncated pyramid (first sub-protrusion C1) and the side height line of the pyramid can be 45 to 60°, that is, the angle 2α between the height lines of the opposite two sides of the quadrangular truncated pyramid can be 90 to 120°. This can mix the light emitted by the light-emitting element 12 as much as possible and prevent total reflection.
[0094] In some embodiments, in the backlight module provided in the present disclosure, as shown in FIG14, the angle between the side surface and the bottom surface of the pyramid (second sub-protrusion C2) is smaller than the angle between the side surface and the bottom surface of the frustum (first sub-protrusion C1), that is, the pyramid is inward relative to the frustum, which is beneficial to improving the uniform light effect.
[0095] It should be noted that Figures 5, 6, 8, 10, and 13-15 are just some of the structures of the protrusion 221 listed in this disclosure, but are not limited to these.
[0096] In some embodiments, in the backlight module provided in the present disclosure, as shown in Figures 1 and 2, the material of the reflective dot structure 23 can be ink, which can be a high-reflectivity ink containing TiO2 mixed with polymers such as acrylate and organic solvents (or some other additives); the thickness of the reflective dot structure 23 can be 5 to 50 μm, and the reflectivity of the reflective dot structure 23 is 40% to 85%. In this way, the part of the light with the strongest light intensity near the positive viewing angle emitted by the light-emitting element 12 will also be partially absorbed by the reflective dot structure 23, so the uniformity of the light coming out through the light diffusion structure 2 will be greatly improved.
[0097] In some embodiments, in the backlight module provided in the present disclosure, as shown in FIG1, FIG2 and FIG16, the reflective dot structure 23 corresponds one-to-one with the light-emitting element 12. The alignment accuracy between the center of the light-emitting element 12 and the center of the reflective dot structure 23 is less than or equal to 0.2mm. That is, the center position of each LED is aligned with the center position of the reflective dot structure 23. Due to the alignment deviation, the alignment accuracy between the two is less than or equal to 0.2mm.
[0098] In some embodiments, in the backlight module provided in the present disclosure, as shown in Figures 17-20, Figures 17-19 are specific structural schematic diagrams of the reflective dot structure 23, Figures 17-19 respectively illustrate four reflective dot structures 23, and Figure 20 is a schematic diagram of the effect of each reflective dot structure 23 in absorbing and reflecting light. Each reflective dot structure 23 includes multiple dots, and the size of the dots gradually decreases from the center of the light-emitting element 12 to the surrounding area. In this way, the large-sized dots aligned with the center of the light-emitting element 12 can absorb a portion of the light 051 with the strongest light intensity near the positive viewing angle emitted by the light-emitting element 12, and reflect the light emitted by the light-emitting element 12 (as indicated by the arrow) to disperse the light and improve the uniform light effect.
[0099] In some embodiments, in the backlight module provided in the present disclosure, as shown in FIG17, the reflective dot structure 23 may include: a first dot 231 aligned with the center of the light-emitting element 12, and at least one ring of second dots 232 arranged around the first dot 231. The present disclosure embodiment takes two rings of second dots 232 as an example; the first dot 231 and the second dot 232 are circular in shape, the area of the first dot 231 is larger than the area of the second dot 232, and there are multiple rings of second dots 232. From the center of the light-emitting element 12 outwards, the number of rings of second dots 232 increases and the area of each ring of second dots 232 decreases.
[0100] In some embodiments, in the backlight module provided in the present disclosure, as shown in FIG18, the reflective dot structure 23 may include: a first dot 231 aligned with the center of the light-emitting element 12, and a plurality of second dots 232 connected to the edge of the first dot 231; the first dot 231 is circular in shape, the second dots 232 are strip-shaped, and the area of the second dots 232 gradually decreases from the center of the light-emitting element 12 to the surrounding area.
[0101] In some embodiments, in the backlight module provided in the present disclosure, as shown in FIG18, the central region of the first dot 231 can be a hollow region V, that is, the central region of the first dot 231 is not provided with ink. By adjusting the size of the hollow region V, the uniform light effect can be further improved.
[0102] In some embodiments, in the backlight module provided in the present disclosure, as shown in FIG19, the reflective dot structure 23 may include: a plurality of closely arranged first dots 231 aligned with the center of the light-emitting element 12, and a plurality of second dots 232 arranged around the first dots 231; the plurality of second dots 232 include a plurality of first sub-dots 2321 adjacent to the periphery of each first dot 231 and a plurality of second sub-dots 2322 dispersed around the periphery of the first sub-dots 2321;
[0103] The first halftone dot 231 and a portion of the first sub-halftone dots 2321 are hexagonal in shape, while the remaining portion of the first sub-halftone dots 2321 and the second sub-halftone dot 2322 are circular in shape. The area of the first halftone dot 231 is larger than the area of the first sub-halftone dot 2321, and the area of the first sub-halftone dot 2321 is larger than the area of the second sub-halftone dot 2322. This results in a more uniform ink distribution around the first halftone dot 231, leading to better light distribution.
[0104] In some embodiments, in the backlight module provided in the present disclosure, as shown in FIG19, the central region of the first sub-dot 2321, which is hexagonal in shape, is a hollow region V, so that the area of the first dot 231 is larger than the area of the first sub-dot 2321, thereby improving the uniform light effect.
[0105] In some embodiments, in the backlight module provided in this disclosure, as shown in FIG21, taking the reflective dot structure 23 shown in FIG17 as an example, the radius r of the area where the first dot 231 is located is... c The formula is h*tan(Θ / 2), where h is the distance from the first dot 231 to the light-emitting element 12, and Θ is the viewing angle when the luminance of the light-emitting element 12 is half of its central luminance. The size of the first dot 231, calculated using the formula h*tan(Θ / 2), can further improve the uniform light distribution effect.
[0106] In some embodiments, in the backlight module provided in this disclosure, as shown in FIG21, the area of the ring of second dots 232 surrounding the first dot 231 can be approximated as (r2) 2 -r1 2 )*cos 2 (θ), r1 is the distance between the center of the first halftone dot 231 and the inner side of a ring of second halftone dots 232, r2 is the distance between the center of the first halftone dot 231 and the outer side of a ring of second halftone dots 232, and θ is the angle between the centerline L1 of the light-emitting element 12 along its thickness direction and the line L2 connecting the center of the light-emitting element 12 and the center of a ring of second halftone dots 232. Thus, using formula (r2) 2 -r1 2 )*cos 2 The size of the second dot 232 obtained by (θ) can further improve the uniform light effect.
[0107] In some embodiments, as shown in FIG4 and FIG16, the light-emitting substrate 1 further includes: a driver chip IC located on the side of the substrate 11 facing the microstructure layer 22, and a first protective adhesive 13 located on the side of the driver chip IC facing the microstructure layer 22 and covering the driver chip IC; wherein, the first protective adhesive 13 may be a high refractive index transparent silicone resin (mainly containing polysiloxane, etc.), with a refractive index of 1.4 to 1.8 and a transmittance of 92% to 100%, and the first protective adhesive 13 is mainly used to protect the driver chip IC from environmental influences;
[0108] As shown in Figure 19, the light-emitting dot structure 23 also includes a third dot 233. The center of the third dot 233 coincides with the center of the driver chip IC, and the area of the third dot 233 is 0.3 to 0.5 times the area of the first protective adhesive 13. Specifically, the driver chip IC itself does not emit light. For OOD backlight module products, the light emitted by the light-emitting element 12 is reflected by the first protective adhesive 13, resulting in a slight bright spot. The blocking effect of the third dot 233 can reduce part of the brightness of the bright spot, thus improving the bright spot defect. In this way, the third dot 233 can improve the problem of IC grid mura caused by the reflection of light by the first protective adhesive 13.
[0109] In some embodiments, in the backlight module provided in the present disclosure, as shown in Figures 1 and 2, in order to further increase the uniform light effect of the light diffusion structure 2, the light diffusion structure 2 further includes a diffusion layer 24 located between the substrate layer 21 and the microstructure layer 22. The material of the diffusion layer 24 can be ink, the thickness of the diffusion layer 24 can be 5 to 100 μm, the haze of the diffusion layer 24 can be 50% to 90%, and the transmittance of the diffusion layer 24 can be 50% to 95%. In addition, the addition of this diffusion layer 24 will also correspondingly increase the fault tolerance of the alignment between the light diffusion structure 2 and the light-emitting substrate 1, and improve the alignment performance.
[0110] In some embodiments of the backlight module provided in this disclosure, as shown in Figures 1 and 2, the light-emitting substrate 1 further includes a reflective layer 14 located on the side of the substrate 11 facing the microstructure layer 22. The reflective layer 14 has a hollowed-out area exposing the light-emitting element 12. The light-emitting substrate 1 also includes a second protective adhesive 15 located on the side of the light-emitting element 12 facing the microstructure layer 22. The second protective adhesive 15 at least covers a portion of the reflective layer 14 surrounding the light-emitting element 12. Specifically, the material of the reflective layer 14 can be white reflective ink. The white reflective ink is a high-reflective ink containing TiO2 mixed with polymers such as acrylate and organic solvents (or with the addition of some other additives), with a reflectivity between 80% and 100%. The white reflective ink is mainly used to reflect the reflective dot structure 23. The light reflected downwards from the microstructure layer 22 and other film layers is reflected back to the film material, improving the light efficiency. The material of the reflective layer 14 can also be a high-reflectivity reflective sheet. The hollow area of the reflective layer 14 is mainly to expose the positive and negative electrodes on the substrate 11 corresponding to each light-emitting element 12. The second protective adhesive 15 can be made of high-refractive-index transparent silicone resin (mainly containing polysiloxane, etc.), with a refractive index of 1.4 to 1.8 and a transmittance of 92% to 100%. The second protective adhesive 15 is mainly used to protect the light-emitting element 12 from environmental influences, and can also improve the light efficiency and reduce the impact of light spill on image quality. Of course, in addition to the Lens shape shown in Figures 1 and 2, the shape of the second protective adhesive 15 can also be a flat adhesive design, that is, the second protective adhesive 15 is a whole layer structure.
[0111] Specifically, as shown in Figures 1 and 2, the light emitted by the light-emitting element 12 is mainly uniformly reflected by multiple reflections between the reflective dot structure 23 and the reflective layer 14, as well as by the absorption of light by the reflective dot structure 23. Combined with the refraction of light by the protrusions 221 of the microstructure layer 22, the uniform light effect is optimized, resulting in a better uniform light effect. In this way, only a thin uniform light film needs to be set to achieve the ideal uniform light effect, making the overall thickness of the backlight module thinner.
[0112] In some embodiments, as shown in Figures 1 and 2, in the backlight module provided in the present disclosure, since the reflective dot structure 23 of the light diffusion structure 2 needs to be aligned and fixed with the light-emitting element 12 on the light-emitting substrate 1, the backlight module of the present disclosure further includes an adhesive layer 4 abutting between the diffusion layer 24 and the substrate 11 and located around the substrate 11. The adhesive layer 4 can be tape or sealant, so that a ring of tape can be attached around the substrate 11 to fix the light diffusion structure 2, or a ring of sealant can be applied around the substrate 11 to fix the light diffusion structure 2. The width of the tape or sealant can be 0.3 to 1.5 mm, and the height of the adhesive layer 4 can be greater than or equal to the sum of the heights of the second protective adhesive 15 and the microstructure layer 22, ensuring that the alignment accuracy between the center of the light-emitting element 12 and the center of the reflective dot structure 23 is ≤0.2 mm.
[0113] As shown in Figure 22, Figure 22 is a comparison diagram of the light uniformity effect of using the light diffusion structure 2 in Figure 1 of this disclosure to uniformly distribute the light emitted by the light-emitting element 12 and the uniformity effect in related technologies. Curve M represents the uniformity effect in related technologies without the light diffusion structure 2, curve N represents the uniformity effect in related technologies with only the reflective dot structure 23, and curve Q represents the uniformity effect of this disclosure. The peak position of each curve is the location of the light-emitting element 12. It can be seen that the uniformity effect gradually increases from curve M→N→Q, and the uniformity effect of this disclosure (curve Q) is improved from 21.5% to 25.7% compared with the uniformity effect in related technologies (curve N). The uniformity effect is the minimum brightness value / maximum brightness value.
[0114] In some embodiments, in the backlight module provided in this disclosure, as shown in FIG1, the light guide structure 3 may include, but is not limited to, at least one of the following: a uniform light film 31, a color conversion film 32, a prism film 33 (BEF), a reflective polarizer 34 (DBEF), and a diffuser film 35. Specifically, when the light-emitting element 12 is a blue LED, a blue-transmitting and red-green-reflecting film 36 may be added or composited below the color conversion film 32; when the light-emitting element 12 is a white LED, the color conversion film 32 is not required. FIG1 of this disclosure shows that the light-emitting element 12 is a blue LED, and the light guide structure 3 includes a uniform light film 31, a blue-transmitting and red-green-reflecting film 36, a color conversion film 32, a prism film 33 (BEF), and a reflective polarizer 34 (DBEF) stacked together. The thickness of the uniform light film 31 may be 0.1 to 0.3 mm. This is because the light diffusion structure 2 used in this disclosure can improve the light uniformity effect, thus reducing the number and thickness of the light uniform film 31. For example, this disclosure only requires one thin light uniform film 31, while related technologies generally use at least two thick light uniform films. Furthermore, when the light diffusion structure 2 of this disclosure achieves a better light uniformity effect, the light uniform film 31 can be directly removed, thereby further reducing the thickness of the backlight module.
[0115] Specifically, as shown in Figure 1, for example, the light-emitting element 12 is a direct-lit blue light source. It is necessary to use the light diffusion structure 2 + uniform light film 31 to mix the light emitted by the light-emitting element 12 evenly (to avoid poor light shadow). Then, the color conversion film 32 is used to convert the blue light into white light. Finally, the prism film 33, the reflective polarizer 34 and the diffusion film 35 are used to increase the brightness and light uniformity.
[0116] In some embodiments, as shown in FIG1, the diffusion film 35 can be a structure with diffusion particles coated on a PET / PC substrate (thickness can be 0.1-0.3 mm), the color conversion film 32 can be a structure containing phosphors or quantum dots (thickness can be 0.2-0.4 mm), the prism film 33 can be 0.2-0.4 mm thick, and the reflective polarizer 34 can be 0.2-0.4 mm thick.
[0117] It should be noted that the structure shown in Figure 1 is only an example of the film structure of the light guide structure 3. In fact, the order of the film structure of the light guide structure 3 can be varied. For example, the order of the film layers can be different, the number of diffusion films 35 can be more than one, the prism film 33 (BEF) may be two or two composite films with prism angles perpendicularly intersecting, and the prism film 33 (BEF) and the reflective polarizer 34 (DBEF) can also be combined, etc.
[0118] In some embodiments, as shown in FIG23, FIG23 is another backlight module structure provided in the present disclosure. The difference between FIG23 and FIG1 is that the film structure of the light guide structure 3 is different. The light guide structure 3 in FIG23 includes a uniform light film 31, a color conversion film 32, a prism film 33 (BEF) and a reflective polarizer 34 (DBEF) stacked together.
[0119] In some embodiments, as shown in FIG24, FIG24 is another backlight module structure provided by the present disclosure. The difference between FIG24 and FIG1 is that the film structure of the light guide structure 3 is different. The light guide structure 3 in FIG24 includes a uniform light film 31, a blue transparent and red-green reflective film 36, a color conversion film 32, and a composite film 37 of DBEF and BEF stacked together.
[0120] In some embodiments, as shown in FIG25, FIG25 is another backlight module structure provided by the present disclosure. The difference between FIG25 and FIG1 is that the film structure of the light guide structure 3 is different. The light guide structure 3 in FIG25 includes a blue transparent and red-green reflective film 36, a color conversion film 32, a light uniform film 31, and a composite film 37 of DBEF and BEF stacked together.
[0121] In some embodiments, as shown in FIG26, FIG26 is another backlight module structure provided by the present disclosure. The difference between FIG26 and FIG1 is that the film structure of the light guide structure 3 is different. The light guide structure 3 in FIG26 includes a uniform light film 31, a blue transparent and red-green reflective film 36, a color conversion film 32, a first prism film 331 (BEF1), a second prism film 332 (BEF2), and a reflective polarizer 34 (DBEF) stacked together.
[0122] In some embodiments, as shown in FIG27, FIG27 is another backlight module structure provided by the present disclosure. The difference between FIG27 and FIG1 is that the film structure of the light guide structure 3 is different. The light guide structure 3 in FIG27 includes a uniform light film 31, a blue transparent and red-green reflective film 36, a color conversion film 32, a first prism film 331 (BEF1), a second prism film 332 (BEF2), and a diffuser film 35 (Diffuser) stacked together.
[0123] In some embodiments, as shown in FIG28, FIG28 is another backlight module structure provided by the present disclosure. The difference between FIG28 and FIG1 is that the film structure of the light guide structure 3 is different. The light guide structure 3 in FIG28 includes a uniform light film 31, a blue transparent and red-green reflective film 36, a color conversion film 32, a diffuser film 35, a prism film 33 (BEF), and a reflective polarizer 34 (DBEF) stacked together.
[0124] It should be noted that the light guide structure 3 in Figures 1 and 23-28 are only some of the structures listed in this disclosure. Of course, there may be other structures, but the common feature of these light guide structures 3 is that the number of light uniform films 31 can be reduced and the thickness can be reduced compared with related technologies, so as to reduce the overall thickness of the backlight module.
[0125] Based on the same inventive concept, this disclosure also provides a display device, including: the backlight module provided in this disclosure, and a display panel located on the light-emitting surface of the backlight module. The principle of this display device in solving the problem is similar to that of the aforementioned backlight module; therefore, the implementation of this display device can refer to the implementation of the aforementioned backlight module, and the repetitions will not be repeated here.
[0126] Specifically, the display panel in this embodiment is a liquid crystal display panel, and the backlight module is disposed below the liquid crystal display panel as a backlight source. It is a direct-lit backlight source. Since the backlight module of this disclosure can improve the uniform light effect and reduce the module thickness, it can provide high-quality backlight for the liquid crystal display panel, improve the display effect and reduce power consumption.
[0127] In specific implementations, the display device provided in the embodiments of this disclosure can be any product or component with display function, such as a mobile phone, tablet computer, television, monitor, laptop computer, digital photo frame, or navigator. Other essential components of this display device are those that should be understood by those skilled in the art and will not be described in detail here, nor should they be construed as limiting this disclosure. Implementation of this display device can refer to the embodiments of the quantum dot light-emitting device described above; repeated details will not be elaborated upon.
[0128] In specific implementations, the display device provided in the embodiments of this disclosure may also include other functional film layers well known to those skilled in the art, which will not be described in detail here.
[0129] This disclosure provides a backlight module and display device. By setting a light diffusion structure composed of a microstructure layer, a substrate layer, and a reflective dot structure on the light-emitting side of the light-emitting substrate, on the one hand, the multiple protrusions of the microstructure layer can refract the light emitted by the light-emitting element to achieve uniform light distribution and optimize the uniform light effect; on the other hand, the reflective dot structure can reflect the light, and the part of the light with the strongest light intensity near the front viewing angle of the light-emitting element will also be partially absorbed by the reflective dot structure, further improving the uniform light effect; in addition, the light-emitting elements are generally arranged in an array, and the brightness difference between the two adjacent light-emitting elements with the largest distance is the largest. This disclosure sets the arrangement direction of the protrusions in the microstructure layer to be parallel to the center line connecting the two adjacent light-emitting elements with the largest distance, so that the direction of the protrusions with the best light diffusion effect is consistent with the center line connecting the two adjacent light-emitting elements with the largest distance, resulting in the best final uniform light effect. Therefore, the uniformity of light emitted through the light diffusion structure in this embodiment is greatly improved. This allows for a reduction in the number or thickness of the light-diffusing film in the light guide structure without affecting the overall strength, flatness, and reliability warp of the backlight module. This reduces the overall thickness of the backlight module, thereby improving its luminous efficiency and reducing its power consumption.
[0130] Obviously, those skilled in the art can make various modifications and variations to this disclosure without departing from its spirit and scope. Therefore, if such modifications and variations fall within the scope of the claims of this disclosure and their equivalents, this disclosure is also intended to include such modifications and variations.
Claims
1. A backlight module, wherein, include: A light-emitting substrate includes a substrate and a plurality of light-emitting elements disposed on one side of the substrate, wherein the light-emitting elements are Mini LEDs; A light diffusion structure includes: a substrate layer located on the light-emitting side of the light-emitting substrate, a microstructure layer located on the side of the substrate layer closer to the light-emitting substrate, and a plurality of reflective dot structures located on the side of the substrate layer away from the light-emitting substrate; wherein, the microstructure layer has a plurality of protrusions on the side closer to the light-emitting substrate, the cross-sectional area of the protrusions gradually increases in the direction away from the light-emitting substrate, and the arrangement direction of the protrusions is parallel to the line connecting the centers of the two adjacent light-emitting elements with the largest distance. A light guide structure is located on the side of the light diffusion structure away from the light-emitting substrate.
2. The backlight module as described in claim 1, wherein, The plurality of light-emitting elements are arranged in a row and column array on the substrate, and the angle between the arrangement direction of the protrusions and the row direction is 40 to 50°.
3. The backlight module as described in claim 2, wherein, The height of the protrusion is 10-50 μm, the bottom surface dimension of the protrusion is 20-100 μm, and the gap width between two adjacent protrusions near the bottom surface of the substrate layer is 0-100 μm.
4. The backlight module as described in claim 3, wherein, The protrusion is in the shape of a pyramid, with the apex of the pyramid facing the side of the light-emitting substrate. The angle between the vertical line from the apex to the side of the pyramid and the vertical line from the apex to the base of the pyramid is 45° to 60°.
5. The backlight module as described in claim 4, wherein, The sides of the base of the pyramid include straight line segments and curved line segments.
6. The backlight module as described in claim 3, wherein, The protrusion includes a first sub-protrusion and a second sub-protrusion stacked together. The first sub-protrusion is close to the substrate layer, and the second sub-protrusion is close to the light-emitting substrate. The first sub-protrusion is shaped like a frustum, and the second sub-protrusion is shaped like a pyramid or an arc-shaped sphere. The bottom surface of the second sub-protrusion away from the light-emitting substrate coincides with the top surface of the first sub-protrusion close to the light-emitting substrate.
7. The backlight module as described in claim 6, wherein, The angle between the elevation line of the frustum and the elevation line of the side surface of the frustum is 45° to 60°.
8. The backlight module as described in claim 7, wherein, The angle between the side face and the base of the pyramid is smaller than the angle between the side face and the base of the frustum.
9. The backlight module as described in any one of claims 1-8, wherein, The reflective dot structure is made of ink, has a thickness of 5–50 μm, and a reflectivity of 40%–85%.
10. The backlight module as described in claim 9, wherein, The reflective dot structure corresponds one-to-one with the light-emitting element, and the alignment accuracy between the center of the light-emitting element and the center of the reflective dot structure is less than or equal to 0.2 mm.
11. The backlight module as claimed in claim 10, wherein, Each of the aforementioned reflective dot structures includes multiple dots, the size of which gradually decreases from the center of the light-emitting element outwards.
12. The backlight module as described in claim 11, wherein, The reflective dot structure includes: a first dot aligned with the center of the light-emitting element, and at least one ring of second dots surrounding the first dot; the first dot and the second dot are circular in shape, the area of the first dot is larger than the area of the second dot, there are multiple second dots in each ring, and the number of second dots in each ring increases and the area of each second dot decreases from the center of the light-emitting element outwards.
13. The backlight module as described in claim 11, wherein, The reflective dot structure includes: a first dot aligned with the center of the light-emitting element, and a plurality of second dots connected to the edge of the first dot; the first dot is circular in shape, the second dots are strip-shaped, and the area of the second dots gradually decreases from the center of the light-emitting element to the surrounding area.
14. The backlight module as described in claim 13, wherein, The central area of the first grid point is a hollow area.
15. The backlight module as described in claim 11, wherein, The reflective dot structure includes: a plurality of closely arranged first dots aligned with the center of the light-emitting element, and a plurality of second dots arranged around the first dots; the plurality of second dots include a plurality of first sub-dots adjacent to the periphery of each of the first dots and a plurality of second sub-dots dispersed around the periphery of the first sub-dots. The first dot and a portion of the first sub-dots are hexagonal in shape, while the other portion of the first sub-dots and the second sub-dots are circular in shape. The area of the first dot is larger than the area of the first sub-dots, and the area of the first sub-dots is larger than the area of the second dot.
16. The backlight module as described in claim 15, wherein, The central area of the first sub-grid, which is hexagonal in shape, is a hollow area.
17. The backlight module as described in any one of claims 12-16, wherein, The radius of the area where the first dot is located is h*tan(Θ / 2), where h is the distance from the first dot to the light-emitting element, and Θ is the viewing angle width when the light-emitting element's luminance is half of its central luminance.
18. The backlight module as claimed in claim 17, wherein, The area of the second network point surrounding the first network point is (r2) 2 -r1 2 )*cos 2 (θ), r1 is the distance between the center of the first halftone dot and the inner side of a circle of second halftone dots, r2 is the distance between the center of the first halftone dot and the outer side of a circle of second halftone dots, and θ is the angle between the center line of the light-emitting element along its thickness direction and the line connecting the center of the light-emitting element and the center of a circle of second halftone dots.
19. The backlight module as described in any one of claims 12-18, wherein, The light-emitting substrate further includes: a driving chip located on the side of the substrate facing the microstructure layer, and a first protective adhesive located on the side of the driving chip facing the microstructure layer and covering the driving chip; The light-emitting dot structure also includes a third dot, the center of which coincides with the center of the driving chip, and the area of the third dot is 0.3 to 0.5 times the area of the first protective adhesive.
20. The backlight module as described in any one of claims 1-19, wherein, The light diffusion structure further includes a diffusion layer located between the substrate layer and the microstructure layer. The material of the diffusion layer is ink, the thickness of the diffusion layer is 5-100 μm, the haze of the diffusion layer is 50%-90%, and the transmittance of the diffusion layer is 50%-95%.
21. The backlight module as claimed in claim 20, wherein, The light-emitting substrate further includes a reflective layer located on the side of the substrate facing the microstructure layer, the reflective layer having a cutout area exposing the light-emitting element, and the light-emitting substrate further includes a second protective adhesive located on the side of the light-emitting element facing the microstructure layer, the second protective adhesive at least covering a portion of the reflective layer surrounding the light-emitting element; The backlight module further includes an adhesive layer that abuts between the diffusion layer and the substrate and is located around the substrate, wherein the height of the adhesive layer is greater than or equal to the sum of the heights of the second protective adhesive and the microstructure layer.
22. The backlight module as described in any one of claims 1-21, wherein, The light guiding structure includes at least one layer of a uniform light film, a color conversion film, a prism film, a reflective polarizer, and a diffusion film, which are stacked together.
23. The backlight module as described in claim 22, wherein, The thickness of the light-diffusing film is 0.1–0.3 mm.
24. A display device, wherein, include: The backlight module as described in any one of claims 1-23, and the display panel located on the light-emitting surface of the backlight module.