Backlight module and display device

Abstract

This application provides a backlight module and a display device. The backlight module includes a light guide plate, a light source, and a brightness enhancement film. The brightness enhancement film is located on one side of the light guide plate and may include a first part, a second part, and a third part stacked sequentially along a target direction. The first part has at least one first prism structure, and the third part has at least one second prism structure. The first part has a first refractive index, the second part has a second refractive index, and the third part has a third refractive index. The second refractive index is less than the first and third refractive indices. The second part can bond the first and second prism structures together to prevent them from sliding against each other, thereby fixing their relative positions. The orthographic projection of the second prism structure onto the first part does not completely coincide with the orthographic projection of the first prism structure onto the first part, thus reducing light leakage over a wide viewing angle and improving light output in a wide viewing angle range of 35° to 65°, thereby enhancing the display effect.

Description

Technical Field

[0001] This application relates to the field of display, and in particular to a backlight module and display device. Background Technology

[0002] The backlight unit (BLU) provides sufficient brightness and a uniformly distributed light source to the display device, enabling it to display images properly. The backlight unit includes a brightness enhancement film (BEF), which can concentrate light from a wider direction of propagation into a smaller angle on the front, thereby achieving light convergence.

[0003] Existing brightness enhancement films are generally single-layer prism structures, which can converge light within a 35° viewing angle in the vertical direction. However, they have poor light output within a wide viewing angle, such as 35° to 65°, and light leakage and waste occur within a viewing angle greater than 65°, which cannot meet customers' requirements for wide viewing angle specifications. Summary of the Invention

[0004] In view of this, the purpose of this application is to provide a backlight module and display device, in which the first prism structure and the second prism structure are located on the same film, which can prevent the first prism structure and the second prism structure from sliding against each other, improve the light output within a wide viewing angle range of 35° to 65°, meet the customer's wide viewing angle light output requirements, and improve the display effect of the display device. The specific solution is as follows:

[0005] In a first aspect, this application provides a backlight module, including:

[0006] A light guide plate, and a light source located in the plane of the light guide plate;

[0007] A brightness enhancement film located on one side of the light guide plate in a target direction perpendicular to the plane of the light guide plate, the brightness enhancement film comprising a first part, a second part and a third part stacked sequentially along the target direction, the first part having at least one first prism structure, and the third part having at least one second prism structure;

[0008] The orthographic projection of the second prism structure onto the first part does not completely coincide with the orthographic projection of the first prism structure onto the first part. The first part has a first refractive index, the second part has a second refractive index, and the third part has a third refractive index. The second refractive index is less than the first refractive index and the third refractive index.

[0009] Secondly, embodiments of this application also provide a display device, including the aforementioned backlight module.

[0010] This application provides a backlight module and display device. The backlight module includes a light guide plate, a light source, and a brightness enhancement film. The light source is located in the plane of the light guide plate. The light guide plate can convert a point light source into a surface light source. In the target direction perpendicular to the plane of the light guide plate, the brightness enhancement film is located on one side of the light guide plate. The brightness enhancement film may include a first part, a second part, and a third part stacked sequentially along the target direction. The first part has at least one first prism structure, and the third part has at least one second prism structure. The first part has a first refractive index, the second part has a second refractive index, and the third part has a third refractive index. The second refractive index is smaller than the first and third refractive indices. The setting of the refractive index can achieve the effect of light convergence in the brightness enhancement film. The second part can bond the first prism structure and the second prism structure together. The first prism structure and the second prism structure are located on the same film, which can prevent the first prism structure and the second prism structure from sliding against each other, thereby fixing their relative positions and ensuring the light output effect. Furthermore, the orthographic projection of the second prism structure onto the first part does not completely coincide with the orthographic projection of the first prism structure onto the first part. Thus, when light emitted from the light source passes through the brightness enhancement film, the first prism structure can converge the light, reducing light leakage at extremely large angles, such as those exceeding a 65° viewing angle. Then, as the light passes through the second prism structure, which is offset from the first prism structure, the light is refracted again within the second prism structure, deflecting inwards. This further reduces light leakage at extremely large viewing angles, thereby improving light output within a wide viewing angle range of 35° to 65°, meeting customers' requirements for wide viewing angles, and enhancing the display effect of the display device. Attached Figure Description

[0011] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0012] Figure 1 This paper shows a schematic diagram of the structure of a backlight module provided in an embodiment of this application;

[0013] Figure 2 This illustration shows a three-dimensional structural diagram of a backlight module provided in an embodiment of this application;

[0014] Figure 3 The following is a schematic diagram illustrating simulation results of a backlight module and a conventional backlight module provided in an embodiment of this application;

[0015] Figure 4 This illustration shows a structural schematic diagram of yet another backlight module provided in an embodiment of this application;

[0016] Figure 5 The following is a schematic diagram illustrating simulation results of another backlight module provided in this application embodiment and a conventional backlight module;

[0017] Figure 6 and Figure 7 This illustration shows a structural schematic diagram of yet another backlight module provided in an embodiment of this application;

[0018] Figure 8 The following is a schematic diagram illustrating simulation results of another backlight module provided in this application embodiment and a conventional backlight module;

[0019] Figure 9 This illustration shows a structural schematic diagram of yet another backlight module provided in an embodiment of this application;

[0020] Figure 10 The following is a schematic diagram illustrating simulation results of another backlight module provided in this application embodiment and a conventional backlight module;

[0021] Figure 11 This illustration shows a structural schematic diagram of yet another backlight module provided in an embodiment of this application;

[0022] Figure 12 This paper shows a three-dimensional structural schematic diagram of another backlight module provided in an embodiment of this application;

[0023] Figure 13 This illustration shows a structural schematic diagram of yet another backlight module provided in an embodiment of this application;

[0024] Figure 14 The following is a schematic diagram illustrating simulation results of another backlight module provided in this application embodiment and a conventional backlight module;

[0025] Figure 15 This illustration shows a structural schematic diagram of yet another backlight module provided in an embodiment of this application;

[0026] Figure 16 This illustration shows a structural schematic diagram of yet another backlight module provided in an embodiment of this application;

[0027] Figure 17 This illustration shows a structural schematic diagram of yet another backlight module provided in an embodiment of this application;

[0028] Figure 18 A schematic diagram of the structure of a display device provided in an embodiment of this application is shown. Detailed Implementation

[0029] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the specific embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0030] Many specific details are set forth in the following description in order to provide a full understanding of this application. However, this application may also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0031] Secondly, this application provides a detailed description in conjunction with schematic diagrams. When detailing the embodiments of this application, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged, not adhering to the usual scale. Furthermore, the schematic diagrams are merely examples and should not limit the scope of protection of this application. In addition, actual fabrication should include three-dimensional spatial dimensions of length, width, and depth.

[0032] For ease of understanding, the following detailed description of a backlight module and display device provided in the embodiments of this application is given in conjunction with the accompanying drawings.

[0033] refer to Figure 1 The diagram shown is a structural schematic of a backlight module provided in an embodiment of this application. The backlight module includes a light source 101, a light guide plate 102, and a brightness enhancement film 103.

[0034] The light source 101 is located within the plane of the light guide plate 102. For example, the light source 101 can be located on the side of the light guide plate 102. The light guide plate 102 can convert a point light source into a surface light source, thereby making the light emitted by the light source 101 more uniform and stable. The direction perpendicular to the plane of the light guide plate 102 can be defined as the target direction. The target direction can be a vertically upward direction. In the target direction, the brightness enhancement film 103 is located on one side of the light guide plate 102, that is, the brightness enhancement film 103 and the light guide plate 102 are stacked.

[0035] The brightness enhancement film 103 may include a first portion 1031, a second portion 1032, and a third portion 1033 stacked sequentially along the target direction. The first portion 1031 has at least one first prism structure 10311, and the third portion 1033 has at least one second prism structure 10331. The second portion 1032 is located between the first prism structure 10311 and the second prism structure 10331. The second portion 1032 can fill the gaps between adjacent first prism structures 10311, thereby providing a flat film surface. In addition, the second portion 1032 can bond the first prism structure 10311 and the second prism structure 10331 together. The first prism structure 10311 and the second prism structure 10331 are located on the same film, which can prevent the first prism structure 10311 and the second prism structure 10331 from sliding against each other, thereby fixing their relative positions and ensuring the light emission effect. The two layers can also reduce the thickness of the brightness enhancement film 103.

[0036] The first portion 1031 of the brightness enhancement film 103 has a first refractive index, the second portion 1032 has a second refractive index, and the third portion 1033 has a third refractive index. The second refractive index is smaller than both the first and third refractive indices. Therefore, in the direction of light emission, the refraction of the brightness enhancement film 103 first decreases and then increases. For example, the first or third refractive index can be greater than or equal to 1.6 and less than or equal to 1.7, and the second refractive index can be greater than or equal to 1.2 and less than or equal to 1.4. Thus, light passing through the first prism structure 10311 and the second prism structure 10331 will be deflected inwards. The setting of the refractive index enables the light to converge within the brightness enhancement film 103.

[0037] The projection of the second prism structure 10331 onto the first part 1031 is not completely coincident with the projection of the first prism structure 10311 onto the first part 1031. When the light emitted from the light source 101 passes through the brightness enhancement film 103, the first prism structure 10311 can converge the light, which can converge light leakage at ultra-large angles, such as light leakage within a viewing angle range greater than 65°. Then, the light passes through the second prism structure 10331. Since the second prism structure 10331 and the first prism structure 10311 are offset from each other, the light passing through the first prism structure 10311 is refracted again in the second prism structure 10331. The light is deflected inward, which can further converge light leakage at ultra-large viewing angles, thereby improving the light output in a wide viewing angle range of 35° to 65°, meeting the customer's requirements for wide viewing angle light output, and improving the display effect of the display device.

[0038] For example, the first and third refractive indices are both 1.6, and the second refractive index is 1.1. According to the refractive index formula, assuming the angle of incidence of light from the first prism structure 10311 to the second part 1032 is 15°, the angle of exit is 22°. The angle of incidence of light from the second part 1032 to the third part 1033 is 67°, and the angle of exit is 39°. If the light emanating from the first prism structure 10311 does not pass through the third part 1033, it will exit at 67°. However, after passing through the third part 1033, the light will be deflected inward, and the angle of incidence into the third part will be 39°, resulting in a change of 28° in the light angle. Subsequently, the light emanating from the second prism structure 10331 will be deflected inward compared to the light emanating directly from the first prism structure 10311. Therefore, the third part 1033 can cause the light to be deflected inward.

[0039] Specifically, the orthographic projections of the second prism structure 10331 and the first prism structure 10311 can partially overlap or completely offset. If the overlap between the first prism structure 10311 and the second prism structure 10331 is relatively large, then after the light rays exit from the first prism structure 10311, it is more difficult for the light rays to enter the second prism structure 10331. Only a small number of light rays at a certain angle can enter the second prism structure 10331. Figure 1 The first prism structure 10311 and the second prism structure 10331 are completely offset, and their orthographic projections do not overlap at all. In this way, compared to partial overlap, the second prism structure 10331 is located in the direction of light emission, and light rays from more angles can enter the second prism structure 10331 after exiting the first prism structure 10311 and be deflected, further improving the brightness of light emitted at large angles.

[0040] In the embodiments of this application, reference is made to Figure 2 As shown, the plurality of first prism structures 10311 in the first part 1031 can be arranged along the first direction, and the plurality of second prism structures 10331 in the third part 1033 can be arranged along the second direction. The first direction is parallel to the plane where the light guide plate 102 is located, and the second direction and the first direction are the same direction. In this way, after the light passes through the first prism structure 10311, it enters the second prism structure 10331 and is deflected, which can improve the output brightness over a wide viewing angle range.

[0041] In this embodiment, the cross-sectional shape of the first prism structure 10311 or the second prism structure 10331 can be triangular, or it can be a triangular prism structure. The triangular prism extends in the plane of the brightness enhancement film 103, and multiple triangular prism structures are arranged in the plane of the brightness enhancement film 103. The extension direction and the arrangement direction of the triangular prisms are perpendicular to each other, which not only ensures the convergence of light at a very large viewing angle, but also makes the manufacturing process of the first prism structure 10311 relatively simple and low-cost. Of course, the cross-sectional shape of the first prism structure 10311 and the second prism structure 10331 can also be quadrilateral or pentagonal, etc.

[0042] Specifically, along the direction perpendicular to the plane of the light guide plate 102 (i.e., the target direction), the section of the first prism structure 10311 or the second prism structure 10331 furthest from the light guide plate 102 on the side away from the light guide plate 102 can be arc-shaped. The cross-sectional shape can be a closed shape composed of an arc and a line segment, which can be represented as an R-angle shape. The R angle can be any angle. This shape has a continuous surface and can converge light from various angles. Compared with the triangular prism structure, it can further improve the convergence effect of light from ultra-wide viewing angles. The light output brightness is higher in the wide viewing angle range of 35° to 65°. In addition, the brightness at the center viewing angle of 0° will also be improved.

[0043] In one possible implementation, the cross-sectional shape of the first prism structure 10311 can be triangular, and the cross-sectional shape of the second prism structure 10331 can be an R-angle shape, as shown in the reference. Figure 1 As shown in Table 1, simulations of a conventional backlight module and the backlight module of this solution yielded the results. Figure 3 Simulation diagram, Figure 3 In this context, (a) represents the brightness level. Figure 3 (b) in the diagram represents a simulation of a conventional backlight module. Figure 3 (c) in the diagram represents the simulation diagram of the backlight module of this scheme.

[0044] Table 1 Simulation results of conventional backlight modules and the backlight module proposed in this solution.

[0045]

[0046]

[0047] In this diagram, Region 1 is defined as the area within a 40° viewing angle along the horizontal axis (H) and within a 20° viewing angle along the vertical axis (V). Region 1 corresponds to the small dashed box area in the diagram. Region 2 is defined as the area within a 45° viewing angle along the horizontal axis (H) and within a 30° viewing angle along the vertical axis (V). Region 2 corresponds to the large dashed box area in the diagram. These ranges will not be repeated hereafter. Both Region 1 and Region 2 are represented by these ranges. The brightness variation in Region 2 can be used to represent the brightness variation within a large viewing angle of 35° to 65°. The elliptical areas in the diagram represent the areas corresponding to the ultra-large viewing angle range (>65°).

[0048] The center brightness of a conventional backlight module is 5322, while the center brightness of the backlight module in this design is 6234, representing a 17% increase. The brightness of the conventional backlight module in region 1 is 3212, while the brightness of the backlight module in this design is 3195, a 1% decrease. The brightness of the conventional backlight module in region 2 is 1766, while the brightness of the backlight module in this design is 2158, a 22% increase. The brightness at the edges of the simulation image is also significantly reduced, indicating a decrease in light leakage at ultra-wide angles and a significant improvement in brightness over a wide viewing angle.

[0049] In one possible implementation, along the direction perpendicular to the plane where the light guide plate 102 is located, the section of the first prism structure 10311 furthest from the light guide plate 102 on the side away from the light guide plate 102 can be arc-shaped, that is, the first prism structure 10311 has an R-angle shape, thereby improving the light output brightness in a wide viewing angle range.

[0050] In another possible implementation, the cross-sectional shapes of the first prism structure 10311 and the second prism structure 10331 can both be R-angle shapes, as shown in the reference. Figure 4 As shown, this maximizes the brightness within a wide viewing angle range of 35° to 65°, while reducing light leakage in ultra-wide viewing angles above 65°. (See Table 2 and...) Figure 5 The simulation results show that, compared with the conventional backlight module, the brightness of region 2 of the proposed backlight module is significantly improved. In addition, the brightness of the center and region 1 are also improved to varying degrees, and the light leakage amplitude at ultra-wide viewing angle is significantly reduced.

[0051] Table 2 Simulation results of conventional backlight modules and the backlight module of this solution

[0052]

[0053] In another possible implementation, the cross-sectional shape of both the first prism structure 10311 and the second prism structure 10331 can be triangular, as shown in the reference. Figure 6 As shown, this approach aims to minimize the production cost of the backlight module while ensuring a wide viewing angle for light output.

[0054] In this embodiment of the application, when the cross-sectional shape of the second prism structure 10331 is triangular, the triangle includes a first hypotenuse, a second hypotenuse, and a base. The first hypotenuse and the second hypotenuse are located on the side of the base away from the light guide plate 102, that is, the cross-sectional shape is an upright triangle. There is a first angle between the first hypotenuse and the base, and a second angle between the second hypotenuse and the base. The first angle and the second angle can be equal, so that the brightness on the left and right sides of the second prism structure 10331 is equal and the light output is more uniform.

[0055] The first angle and the second angle may not be equal; see reference. Figure 7 As shown, the different inclinations of the first and second hypotenuses result in different light refraction. For example, if the first angle is greater than the second angle, the angle between the first hypotenuse and the target direction is smaller, while the angle between the second hypotenuse and the target direction is larger. The second hypotenuse is also longer, allowing more light to be refracted on the slope where the second hypotenuse is located, while less light is refracted on the slope where the first hypotenuse is located. This increases the brightness over a wide viewing angle on one side of the second hypotenuse, causing the light pattern to shift to one side to meet the customer's specific needs.

[0056] Specifically, the first angle can be smaller than the second angle. The first angle can be greater than or equal to 25° and less than or equal to 35°, which can satisfy the effect of the light pattern shifting to one side and also ensure the light output from a wide angle.

[0057] In one possible implementation, the cross-sectional shape of the first prism structure 10311 and the second prism structure 10331 is triangular, and the first angle and the second angle of the second prism structure 10331 are not equal, according to Table 3 and... Figure 8 Simulation results show that the brightness of region 2 is significantly improved by 69%, and the light pattern shifts to one side.

[0058] Table 3 Simulation results of conventional backlight module and backlight module of this solution

[0059]

[0060] In this embodiment of the application, when the first direction and the second direction are the same, in the first direction, there is a first distance between the centers of adjacent first prism structures 10311, and in the second direction, there is a second distance between the centers of adjacent second prism structures 10331. The first distance can be greater than the second distance. Specifically, the first distance can be an integer multiple of the second distance, such as twice the second distance, or three, four, five or six times. In this way, multiple second prism structures 10331 can be correspondingly arranged between adjacent first prism structures 10311. The number of second prism structures 10331 is greater than the number of first prism structures 10311, thereby making the light emitted from the second prism structures 10331 more delicate and the light more uniform.

[0061] In one possible implementation, the first prism structure 10311 has a triangular cross-sectional shape, and the second prism structure 10331 has a rounded cross-sectional shape. (Refer to...) Figure 9 As shown, there are two second prism structures 10331 between adjacent first prism structures 10311, according to Table 4 and Figure 10 Simulation results show that the brightness of region 2 is significantly improved.

[0062] Table 4 Simulation results of conventional backlight modules and the backlight module of this solution

[0063]

[0064] In another possible implementation, the cross-sectional shape of both the first prism structure 10311 and the second prism structure 10331 is triangular, and the first distance is twice the second distance. (Refer to...) Figure 11 As shown.

[0065] In this embodiment, multiple first prism structures 10311 can be arranged along a first direction, and multiple second prism structures 10331 can be arranged along a second direction. The second direction can be located in the plane of the light guide plate 102 and is perpendicular to the first direction. That is, the first prism structures 10311 and the second prism structures 10331 are arranged along different directions, as shown in the reference. Figure 12 As shown and Figure 13 As shown, Figure 13 for Figure 12 In the cross-sectional diagram along the AA direction, this allows for light collection in both the first and second directions, resulting in a more circular light pattern and similar brightness variations across all directions, thus improving display uniformity.

[0066] According to Table 5 and Figure 14 Simulation results show that the center brightness is significantly improved, and light leakage at ultra-large angles is greatly reduced.

[0067] Table 5 Simulation results of conventional backlight module and backlight module of this solution

[0068]

[0069] In this embodiment, the backlight module may further include a fixing frame, as shown in the reference. Figure 15 and Figure 16 As shown, Figure 15 This is a schematic diagram when the first and second directions are the same. Figure 16 This is a schematic diagram showing the first and second directions being perpendicular. The fixing frame 107 is located around the brightness enhancement film 103 and is used to fix the brightness enhancement film 103. In the first direction, there is a third distance x between the brightness enhancement film 103 and the fixing frame 107. In the first direction, the first prism structure 10311 has a first width w1, and in the second direction, the second prism structure 10331 has a second width w2. The third distance x is greater than the first width w1 and the second width w2. The first width w1 or the second width w2 can be greater than or equal to 20 micrometers and less than or equal to 50 micrometers. Thus, the gap width between the brightness enhancement film 103 and the fixing frame 107 is greater than the widths of the first prism structure 10311 and the second prism structure 10331. This allows for a gap so that the first prism structure 10311 and the second prism structure 10331 can be staggered, avoiding a gap width that would prevent staggering and ensuring sufficient space for the brightness enhancement film 103 structure with the first prism structure 10311 and the second prism structure 10331.

[0070] In the embodiments of this application, reference is made to Figure 17As shown, the backlight module may also include a reflective film 104, a diffuser film 105, and a multilayer reflective polarizing film 106. The reflective film 104 is located on the side of the light guide plate 102 away from the brightness enhancement film 103, and can reflect the light leaking from the bottom of the light guide plate 102 back to the light guide plate 102 for reuse. The diffuser film 105 is located between the light guide plate 102 and the brightness enhancement film 103, and can play a role in light uniformity. The multilayer reflective polarizing film 106 is located on the side of the brightness enhancement film 103 away from the light guide plate 102. That is to say, the backlight module includes a reflective film 104, a light guide plate 102, a diffuser film 105, a brightness enhancement film 103, and a multilayer reflective polarizing film 106 stacked in sequence.

[0071] This application provides a backlight module, which includes a light guide plate, a light source, and a brightness enhancement film. The light source is located in the plane of the light guide plate, which can convert a point light source into a surface light source. In the target direction perpendicular to the plane of the light guide plate, the brightness enhancement film is located on one side of the light guide plate. The brightness enhancement film may include a first part, a second part, and a third part stacked sequentially along the target direction. The first part has at least one first prism structure, and the third part has at least one second prism structure. The first part has a first refractive index, the second part has a second refractive index, and the third part has a third refractive index. The second refractive index is smaller than the first and third refractive indices. The setting of the refractive index can achieve the effect of light convergence in the brightness enhancement film. The second part can bond the first prism structure and the second prism structure together. The first prism structure and the second prism structure are located on the same film, which can prevent the first prism structure and the second prism structure from sliding against each other, thereby fixing their relative positions and ensuring the light output effect. Furthermore, the orthographic projection of the second prism structure onto the first part does not completely coincide with the orthographic projection of the first prism structure onto the first part. Thus, when light emitted from the light source passes through the brightness enhancement film, the first prism structure can converge the light, reducing light leakage at extremely large angles, such as those exceeding a 65° viewing angle. Then, as the light passes through the second prism structure, which is offset from the first prism structure, the light is refracted again within the second prism structure, deflecting inwards. This further reduces light leakage at extremely large viewing angles, thereby improving light output within a wide viewing angle range of 35° to 65°, meeting customers' requirements for wide viewing angles, and enhancing the display effect of the display device.

[0072] A backlight module based on the above embodiments, such as Figure 18As shown, this application embodiment also provides a display device, which can be any electronic device with display function, such as a touch screen, mobile phone, tablet computer, laptop computer, or television. The display device includes the aforementioned backlight module, and has a display area AA and a non-display area NA. The non-display area surrounds the display area. The display area AA includes a first display area 100 and a second display area 200. The display area is used to house light-emitting elements, and the first display area 100 can house a camera. The non-display area NA is used to house wiring. This display device uses the aforementioned backlight module. Because the second prism structure is offset from the first prism structure, the light passing through the first prism structure is refracted again in the second prism structure, causing the light to deflect inwards. This further reduces light leakage over a wide viewing angle, thereby improving light output within a wide viewing angle range of 35° to 65°, meeting customers' requirements for wide viewing angle light output, and improving the display effect of the display device.

[0073] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0074] The above description is merely a preferred embodiment of this application. Although this application has disclosed preferred embodiments above, it is not intended to limit this application. Any person skilled in the art can make many possible variations and modifications to the technical solutions of this application using the methods and techniques disclosed above, or modify them into equivalent embodiments with equivalent changes, without departing from the scope of the technical solutions of this application. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of this application without departing from the content of the technical solutions of this application shall still fall within the protection scope of the technical solutions of this application.

Claims

1. A backlight module, characterized in that, include: A light guide plate, and a light source located in the plane of the light guide plate; A brightness enhancement film located on one side of the light guide plate in a target direction perpendicular to the plane of the light guide plate, the brightness enhancement film comprising a first part, a second part and a third part stacked sequentially along the target direction, the first part having at least one first prism structure, and the third part having at least one second prism structure; The orthographic projection of the second prism structure onto the first part does not coincide with the orthographic projection of the first prism structure onto the first part. The first part has a first refractive index, the second part has a second refractive index, and the third part has a third refractive index. The second refractive index is less than the first refractive index and the third refractive index. The first part has a plurality of first prism structures arranged along a first direction, and the third part has a plurality of second prism structures arranged along a second direction, wherein the first direction is parallel to the plane in which the light guide plate is located. The second direction is the same as the first direction, or the second direction is located in the plane of the light guide plate and is perpendicular to the first direction.

2. The backlight module of claim 1, wherein, The cross-sectional shape of the first prism structure or the second prism structure is triangular or along a direction perpendicular to the plane of the light guide plate, and the section of the first prism structure or the second prism structure furthest from the light guide plate on the side away from the light guide plate is arc-shaped.

3. The backlight module of claim 2, wherein, Along the direction perpendicular to the plane where the light guide plate is located, the section of the first prism structure furthest from the light guide plate on the side away from the light guide plate is arc-shaped.

4. The backlight module of claim 2, wherein, The cross-sectional shape of the second prism structure is triangular, the triangle includes a first hypotenuse, a second hypotenuse, and a base. The first hypotenuse and the second hypotenuse are located on the side of the base away from the light guide plate. There is a first angle between the first hypotenuse and the base, and a second angle between the second hypotenuse and the base. The first angle and the second angle are not equal.

5. The backlight module according to claim 4, characterized in that, The first angle is smaller than the second angle, and the first angle is greater than or equal to 25° and less than or equal to 35°.

6. The backlight module according to claim 1, characterized in that, The first part has a plurality of first prism structures arranged along a first direction, and the third part has a plurality of second prism structures arranged along a second direction, wherein the first direction is parallel to the plane in which the light guide plate is located. The second direction is the same as the first direction, or the second direction is located in the plane of the light guide plate and is perpendicular to the first direction.

7. The backlight module according to claim 6, characterized in that, When the first direction and the second direction are the same, in the first direction, there is a first distance between the centers of adjacent first prism structures, and in the second direction, there is a second distance between the centers of adjacent second prism structures, wherein the first distance is an integer multiple of the second distance.

8. The backlight module according to claim 6, characterized in that, The backlight module also includes a fixing frame, which is located around the brightness enhancement film. In the first direction, there is a third distance between the brightness enhancement film and the fixing frame. In the first direction, the first prism structure has a first width, and in the second direction, the second prism structure has a second width, and the third distance is greater than the first width and the second width.

9. The backlight module according to claim 8, characterized in that, The first width or the second width is greater than or equal to 20 micrometers and less than or equal to 50 micrometers.

10. The backlight module according to claim 1, characterized in that, The backlight module also includes: A reflective film located on the side of the light guide plate away from the brightness enhancement film; A diffusion film located between the light guide plate and the brightness enhancement film; A multilayer reflective polarizing film located on the side of the brightness enhancement film away from the light guide plate.

11. A display device, characterized in that, Includes the backlight module as described in any one of claims 1-10.

Images