Large area direct-lit backlight module that can compensate for edge brightness

Abstract

The present invention proposes a large-area direct-type backlight module that can compensate for edge brightness, including a light guide plate, a corner-entry backlight source, a side-entry backlight source, an edge reflector, a direct-type backlight module, a reflective sheet, and an optical film. A semi-ellipsoidal concave microstructure is arranged at the bottom of the light guide plate, and a direct-type light source is arranged at the center of the microstructure. The light guide plate is de-cornered, and the four corners are polished to form a flat light incident surface. A corner-entry light source is arranged, and a side-entry backlight source is placed at a location where the illumination of the four sides is relatively low. In the backlight module provided by the present invention, the direct-type light source is arranged at the center of the microstructure, which reduces the thickness of the backlight module and increases the uniformity of light output. The arrangement of the corner-entry light source and the side-entry light source solves the problems of uneven edge brightness in the existing direct-type backlight display device, excessive power consumption, and insufficient heat dissipation due to excessive use of LED light sources.

Description

Technical Field

[0001] The invention belongs to the technical field of display device backlight modules, and in particular relates to a large-area direct-type backlight module capable of compensating edge brightness. Background Art

[0002] In the development of LCD, the design of backlight module plays an indispensable role. Backlight module is composed of light source, light guide plate, reflector, dots and optical film. According to the position of light source, backlight module can be divided into direct type and edge type. Edge type backlight module has its light source located on the side of light guide plate. As the distance from the light source increases, the brightness decreases and the resolution is low, so it is not suitable for large-area display devices.

[0003] The prior art discloses a direct-type backlight display device CN209765923U, in which a surrounding reflective structure is arranged around each LED light source, so as to collect, reflect and converge light within a large angle range around the LED light source, and use part of the light reflected by the light source to compensate for the light output of the light output layer of the backlight module, thereby enhancing the light output uniformity of the backlight module. However, this display device still needs to use a large number of direct-type light sources, the manufacturing cost is too high, and the heat dissipation capacity is poor, the service life is short, and it is difficult to achieve the expectation of long-term use of the display device.

[0004] The prior art discloses a direct-down and side-input backlight display device CN109725464B, which has a direct-down backlight on the upper part and a side-input backlight on the lower part, thereby improving the rear appearance of the liquid crystal display device and controlling the cost. However, this display device still has uneven edge brightness and distinct black and white spots in the direct-down backlight area, and it is also unable to achieve regional brightness adjustment, making it difficult to meet people's demand for picture flexibility. Summary of the invention

[0005] In order to overcome the defects and shortcomings of the prior art, the purpose of the present invention is to provide a large-area direct-type backlight module that can compensate for edge brightness. It includes a light guide plate, a corner-entry backlight source, a side-entry backlight source, an edge reflector, a direct-type backlight module, a reflective sheet and an optical film. A semi-ellipsoidal concave microstructure is arranged at the bottom of the light guide plate, and a direct-type light source is arranged at the center of the microstructure. The light guide plate is de-cornered, and the four corners are polished to form a flat light incident surface. A corner-entry light source is arranged, and a side-entry backlight source is placed at a location where the illumination on the four sides is relatively low. In the backlight module provided by the present invention, the direct-type light source is arranged at the center of the microstructure, which reduces the thickness of the backlight module and increases the uniformity of light output. The arrangement of the corner-entry light source and the side-entry light source solves the problems of uneven edge brightness in the existing direct-type backlight display device, excessive power consumption and insufficient heat dissipation caused by too much LED light source.

[0006] The method adopts the method of setting the direct-down light source at the center of the semi-ellipsoidal concave microstructure, and utilizing the microstructure to enhance the transmission efficiency and luminous efficiency of the direct-down light source; and the light guide plate is de-cornered, the four corners are polished to form a flat light-entering surface, and the corner-entry backlight source is placed at the cross section of the flat shape corner area of ​​the four corners of the light guide plate; in addition, the display device sets a side-entry backlight source at the four sides where the illumination is low, and the direct-down backlight source and the side-entry backlight source are driven by two different sets of driving circuits. The advantage of the present invention is that the setting of the corner-entry light source and the side-entry light source can compensate for the edge brightness of the backlight module, solve the problem of uneven edge brightness of the traditional direct-down backlight module, and at the same time greatly reduce the amount of backlight source, reduce the area of ​​the direct-down backlight area, enhance the heat dissipation capacity of the display device, extend its service life, and also reduce the production cost of the display device.

[0007] The technical solution adopted by the present invention to solve the technical problem is:

[0008] A large-area direct-type backlight module capable of compensating edge brightness, characterized by comprising a light guide plate, a corner-entry backlight source, a side-entry backlight source, an edge reflector, a direct-type backlight module, a reflective sheet and an optical film;

[0009] The direct-down backlight module is located at the bottom of the light guide plate, and includes a plurality of direct-down backlight sources and a semi-ellipsoidal concave microstructure, each of which is arranged at the center of the semi-ellipsoidal concave microstructure and faces the light guide plate;

[0010] The light guide plate is de-edged, and the four corners are polished to form a flat light-entering surface, and a corner-entry backlight source is arranged in the corner plane area, and a side-entry backlight source is arranged at the four sides of the light guide plate where the illumination is low;

[0011] The edge reflector surrounds the four sides of the light guide plate and completely covers the corner-entry backlight source and the edge-entry backlight source;

[0012] The direct-lit backlight source and the edge-lit backlight source are driven by different driver chips;

[0013] The reflective sheet is located on the lower surface of the light guide plate and is used to reflect the light transmitted from the bottom of the light guide plate to increase the utilization rate of the light source;

[0014] The optical film comprises a diffusion sheet and a prism sheet placed orthogonally, and is located on the upper surface of the light guide plate.

[0015] Furthermore, the direct-type backlight module includes a plurality of direct-type backlight sources, which are embedded in the center of the semi-ellipsoidal concave microstructure at the bottom of the light guide plate, and the area of ​​the direct-type backlight region occupies less than 60% of the area of ​​the light guide plate.

[0016] Furthermore, the distances between two adjacent direct-type backlight sources are L and D respectively, and they are arranged in an n×m matrix, and the area of ​​the applied display device is not less than 46 inches.

[0017] Furthermore, the light guide plate is subjected to a corner removal treatment specifically by grinding and polishing the four corners to form a planar light incident surface, so that the right-angled corner area of ​​the light guide plate is changed into a planar corner area, and the corner-entry backlight source is placed at the cross section of the planar corner area of ​​the four corners of the light guide plate, and I is defined. 0 is the light intensity of the corner-input backlight source, α is the angle of the light guide plate after the corners are removed, α is set to 120°, and the light intensity at the edge of the light guide plate is I 0 ×cos(α-90°).

[0018] Furthermore, a side rectangular coordinate system is established, the light source is placed on the zox plane, the light guide plate is placed on the yox plane, the light propagates on the zoy plane, and the edge light illumination of the light guide plate satisfies the following formula:

[0019]

[0020] In the formula, E V Indicates the illuminance value at point P, at E V When the value is lower than 80%, an edge-entry backlight is set to achieve edge compensation.

[0021] Furthermore, the corner-entry backlight source, edge-entry backlight source and direct-down backlight source use one or more of high-power 2835 lamp beads, 3528 lamp beads, 5050 lamp beads or 3535 lamp beads.

[0022] Furthermore, based on the brightness of the direct backlight area, the driving circuit of the edge backlight source is adjusted so that the full-screen brightness uniformity of the display device reaches more than 80%.

[0023] Furthermore, the material of the light guide plate is one or more of polymethyl methacrylate, polystyrene, cycloolefin polymer, cycloolefin copolymer, polycarbonate, and polydimethylphenylsiloxane.

[0024] Furthermore, the edge of the light guide plate is surrounded by an edge reflector; the material of the edge reflector is one or more of polyethylene terephthalate, polyurethane resin, polycarbonate, polyethylene, and polymethyl methacrylate.

[0025] Further, the following steps are adopted for production:

[0026] Step S1: manufacturing a light guide plate unit;

[0027] Step S2: making a semi-ellipsoidal concave microstructure at the bottom of the light guide plate; performing a corner removal treatment on the light guide plate, grinding and polishing the four corners to form a flat light incident surface, so that the right-angled corner area of ​​the light guide plate becomes a flat corner area;

[0028] Step S3: embedding a direct-lit backlight source at the center of the microstructure and facing the light guide plate; placing a corner-lit backlight source at the cross-section of the planar corner regions of the four corners of the light guide plate;

[0029] Step S4: placing an edge-type backlight source at locations where the illumination on the four sides of the light guide plate is relatively low;

[0030] Step S5: surround the edge of the light guide plate with an edge reflector to completely cover the corner-type backlight source and the edge-type backlight source;

[0031] Step S5: adding a reflective sheet on the lower surface of the light guide plate to reflect the light transmitted from the bottom of the light guide plate to improve the utilization rate of the light source;

[0032] Step S6: adding an optical film on the upper surface of the light guide plate, including a diffuser and an orthogonally placed prism film.

[0033] Compared with the prior art, the present invention and its preferred embodiment provide a large-area direct-type backlight module capable of compensating for edge brightness, and the design of the corner-entry backlight source provided greatly reduces the amount of backlight source used in conventional direct-type backlight display devices, and reduces the area of ​​the direct-type backlight region; in addition, in order to address the problems of edge brightness attenuation and the occurrence of bright and dark spots in existing direct-type backlight display devices, a side-entry backlight source is arranged at a position with low illumination on the four sides of the light guide plate to compensate for edge brightness; in addition, the display device uses two sets of different driving circuits to drive the direct-type backlight source and the side-entry backlight source, so that the full-screen brightness uniformity of the display device reaches more than 80%. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0035] Figure 1 It is a structural top view of an embodiment of a large-area direct-lit backlight module capable of compensating edge brightness of the present invention;

[0036] Figure 2 This is a direct-type backlight module arrangement diagram of an embodiment of a large-area direct-type backlight module capable of compensating edge brightness of the present invention;

[0037] Figure 3 yes Figure 2 The enlarged schematic diagram of middle Ⅰ;

[0038] Figure 4It is a structural cross-sectional view of an embodiment of a large-area direct-lit backlight module capable of compensating edge brightness of the present invention;

[0039] Figure 5 is a schematic diagram of a side rectangular coordinate system of a large-area direct-lit backlight module capable of compensating edge brightness according to an embodiment of the present invention;

[0040] In the figure: 1-light guide plate; 2-corner backlight source; 3-side backlight source; 4-semi-ellipsoidal concave microstructure; 5-direct backlight source; 6-direct backlight module; 7-edge reflector; 8-reflector sheet; 9-optical film. DETAILED DESCRIPTION

[0041] In order to make the features and advantages of this patent more obvious and easy to understand, the following embodiments are specifically described in detail as follows:

[0042] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used in this specification have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0043] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0044] like Figure 1-Figure 5 As shown, the large-area direct-type backlight module capable of compensating edge brightness provided by the embodiment of the present invention includes: a light guide plate 1, a corner-entry backlight source 2, a side-entry backlight source 3, an edge reflector 7, a direct-type backlight module 6, a reflector sheet 8, an optical film 9 and other structures.

[0045] The direct-type backlight module is located at the bottom of the light guide plate, and includes a plurality of direct-type backlight sources 5 and a semi-ellipsoidal concave microstructure 4, each of which is arranged at the center of the semi-ellipsoidal concave microstructure and faces the light guide plate;

[0046] The light guide plate is processed with corners, and the four corners are polished to form a flat light-entering surface. A corner-entry backlight source is set in the corner plane area, and a side-entry backlight source is set at the four sides of the light guide plate where the illumination is low;

[0047] The edge reflector surrounds the four sides of the light guide plate, completely covering the corner-type backlight source and the edge-type backlight source;

[0048] The direct-lit backlight source and the edge-lit backlight source are driven by different driver chips;

[0049] The reflective sheet is located on the lower surface of the light guide plate to reflect the light transmitted from the bottom of the light guide plate to increase the utilization rate of the light source; the optical film includes a diffuser and an orthogonally placed prism sheet, and is located on the upper surface of the light guide plate.

[0050] In this embodiment, as a preferred solution, the direct-down backlight module is located at the bottom of the light guide plate. The direct-down backlight module includes multiple direct-down backlight sources. The direct-down backlight sources are embedded in the center of the semi-ellipsoidal concave microstructure at the bottom of the light guide plate, and the area of ​​the direct-down backlight region is within 60% of the area of ​​the light guide plate.

[0051] In this embodiment, as a preferred solution, the distances between two adjacent direct-lit backlight sources are L and D respectively, and they are arranged in an n×m matrix, and the display device area is not less than 46 inches.

[0052] In this embodiment, as a preferred solution, the light guide plate is subjected to a corner removal treatment, and the four corners are ground and polished to form a flat light incident surface, so that the right-angled corner area of ​​the light guide plate is changed into a flat corner area, and the corner-entry backlight source is placed at the cross section of the flat corner area of ​​the four corners of the light guide plate, and I is defined. 0 is the light intensity of the corner-input backlight source, α is the angle of the light guide plate after the corners are removed, and α is set to 120°, so the light intensity at the edge of the light guide plate is I 0 ×cos(α-90°).

[0053] In this embodiment, as a preferred solution, a rectangular coordinate system is established, the light source is placed on the zox plane, the light guide plate is placed on the yox plane, the light propagates on the zoy plane, and the edge light illumination of the light guide plate satisfies the following formula:

[0054]

[0055] In the formula, E V Indicates the illuminance value at point P, at E V When the value is lower than 80%, an edge-entry backlight is set to achieve edge compensation.

[0056] In this embodiment, as a preferred solution, the corner-entry backlight source, the edge-entry backlight source and the direct-down backlight source use one or more combinations of high-power 2835 lamp beads, 3528 lamp beads, 5050 lamp beads or 3535 lamp beads.

[0057] In this embodiment, as a preferred solution, the direct-type backlight source and the edge-type backlight source are driven by different driving circuits. Based on the brightness of the direct-type backlight area, the driving circuit of the edge-type backlight source is adjusted to make the full-screen brightness uniformity of the display device reach more than 80%.

[0058] In this embodiment, as a preferred solution, the material of the light guide plate is one or more combinations of polymethyl methacrylate, polystyrene, cycloolefin polymer, cycloolefin copolymer, polycarbonate, and polydimethylphenylsiloxane.

[0059] In this embodiment, as a preferred solution, the edge of the light guide plate is surrounded by an edge reflector, and the material of the edge reflector is one or more combinations of polyethylene terephthalate, polyurethane resin, polycarbonate, polyethylene, and polymethyl methacrylate.

[0060] In this embodiment, as a preferred solution, the manufacturing method of the backlight display device is as follows:

[0061] (1) Manufacturing a light guide plate unit;

[0062] (2) a semi-ellipsoidal concave microstructure is provided at the bottom of the light guide plate, and a direct-lit backlight source is embedded at the center of the microstructure, facing the light guide plate;

[0063] (3) performing a corner removal treatment on the light guide plate, grinding and polishing the four corners to form a flat light incident surface, so that the right-angled corner area of ​​the light guide plate becomes a flat corner area, and placing the corner-entry backlight source at the cross section of the flat corner area of ​​the four corners of the light guide plate;

[0064] (4) Place an edge-entry backlight source at the lower illumination areas on the four sides of the light guide plate;

[0065] (5) A circle of edge reflectors surrounds the edge of the light guide plate to completely cover the corner-entry backlight source and the edge-entry backlight source;

[0066] (6) Add a reflective sheet on the lower surface of the light guide plate to reflect the light transmitted from the bottom of the light guide plate to improve the utilization rate of the light source;

[0067] (7) Add optical films such as a diffuser and orthogonally placed prisms to the upper surface of the light guide plate.

[0068] The following is a more detailed introduction to the present embodiment by taking a specific example as an example:

[0069] like Figure 1As shown, it is a top view of a large-area direct-type backlight module that can compensate for edge brightness provided by the present invention. It is determined that 1-the light guide plate is a light guide plate made of polymethyl methacrylate PMMA. In order to enhance the hardness of the light guide plate and prevent it from being damaged during production and transportation, 28 kg of polymethyl methacrylate PMMA, 15 kg of polycarbonate PC, 2 kg of light diffuser, 0.6 kg of light stabilizer, 0.3 kg of heat stabilizer, and 2.5 kg of silicone masterbatch and 7 kg of fused quartz sand are added, stirred to make them completely mixed, and the material is heated to 460°C. After it is completely dissolved, it is injected into the mold to be cooled and formed. Silicone masterbatch and fused quartz sand are used to improve the surface hardness of the light guide plate. In addition, silicone masterbatch can also act as a lubricant.

[0070] A 4-semi-ellipsoid concave microstructure is made at the bottom of the light guide plate using etching technology. The microstructure is etched into a curved surface on one side facing the light guide plate and a flat surface on the other side. A concave cavity for accommodating a direct-type backlight source is provided at the center of the microstructure. Tiny protrusions of the same size and shape are evenly distributed on the plane outside the concave cavity. The height of the tiny protrusions is 0.1mm, which changes the angle of the direct-type backlight source to obtain a larger light spot. 2835LED lamp beads are selected as 5-direct-type backlight sources, with a single brightness of 22 lumens, which reduces the use of direct-type light sources, and the bottom of the lamp beads has a heat sink for direct heat conduction, enhancing the heat dissipation capacity of the display device and extending the life of the device.

[0071] 2835LED lamp beads are selected as 2-corner backlight sources in the four corners of the light guide plate. The size of the LED lamp beads is L*W*H 2.8mm*3.5mm*0.7mm. Since the full angle of the lamp beads is 120°, the light guide plate is de-cornered and the four corners are polished to form a flat light-entering surface, so that the right-angle corner area of ​​the light guide plate becomes a flat corner area. The angle α after processing is 120°, so the edge light intensity of the light guide plate is I 0 ×cos(α-90°). Two corner-entry backlight sources are placed at the cross-section of the planar shape corner areas of the four corners of the light guide plate, thereby reducing the amount of backlight sources used.

[0072] 2835LED lamp beads are selected around the light guide plate as 3-side-entry backlight sources, and the light intensity at the edge of the light guide plate is I 0 ×cos(α-90°), establish a rectangular coordinate system, place the light source on the zox plane, place the light guide plate on the yox plane, and the light propagates on the zoy plane. The light guide plate edge illumination satisfies the formula: The side-entry backlight sources are placed at a distance R around the light guide plate, thereby achieving edge brightness compensation for a large area of ​​direct-type backlight.

[0073] The direct-type backlight source and the edge-type backlight source are driven by two different sets of driving circuits. Based on the brightness of the direct-type backlight area, the current-limiting resistor value of the edge-type backlight source is adjusted to be slightly smaller than the current-limiting resistor value of the direct-type backlight source, so that the full-screen brightness uniformity of the display device reaches more than 80%.

[0074] The polyurethane resin is placed in the mold, and the mold and the polyurethane resin are heated to 120°C. The polyurethane resin is pressed and molded under constant temperature heating. After the polyurethane resin is pressed, a vacuum treatment is performed so that the polyurethane resin can be adsorbed and molded. After a period of constant temperature and constant heat in the mold closing state, the mold is cooled, and the mold is separated after cooling to a certain temperature. Finally, the polyurethane resin is cooled at room temperature using a blowing cooling device to complete the demoulding step, thereby forming a 7-edge reflector, which is set at the edge of the light guide plate to enhance the light utilization rate of the corner-entry backlight source and the side-entry backlight source.

[0075] The above is only a preferred embodiment of the present invention, and does not limit the present invention in other forms. Any technician familiar with the profession may use the above disclosed technical content to change or modify it into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention still belongs to the protection scope of the technical solution of the present invention.

[0076] This patent is not limited to the above-mentioned optimal implementation mode. Anyone can derive other various forms of large-area direct-lit backlight modules that can compensate for edge brightness under the inspiration of this patent. All equivalent changes and modifications made according to the scope of the patent application of the present invention should be covered by this patent.

Claims

1. A large-area direct-lit backlight module capable of compensating edge brightness, characterized in that: Including light guide plate, corner backlight source, side backlight source, edge reflector, direct backlight module, reflector and optical film; The direct-down backlight module is located at the bottom of the light guide plate, and includes a plurality of direct-down backlight sources and a semi-ellipsoidal concave microstructure, each of which is arranged at the center of the semi-ellipsoidal concave microstructure and faces the light guide plate; The light guide plate is de-edged, and the four corners are polished to form a flat light-entering surface, and a corner-entry backlight source is arranged in the corner plane area, and a side-entry backlight source is arranged at the four sides of the light guide plate where the illumination is low; The edge reflector surrounds the four sides of the light guide plate and completely covers the corner-entry backlight source and the edge-entry backlight source; The direct-lit backlight source and the edge-lit backlight source are driven by different driver chips; The reflective sheet is located on the lower surface of the light guide plate and is used to reflect the light transmitted from the bottom of the light guide plate to increase the utilization rate of the light source; The optical film comprises a diffusion sheet and an orthogonally placed prism sheet, and is located on the upper surface of the light guide plate; The light guide plate is subjected to de-edging treatment specifically as follows: the four corners are ground and polished to form a flat light incident surface, so that the right-angled corner areas of the light guide plate are transformed into flat corner areas, and the corner-entry backlight source is placed at the cross-section of the flat corner areas of the four corners of the light guide plate, I0 is defined as the light intensity of the corner-entry backlight source, α is the angle of the light guide plate after de-edging, α is set to 120°, and the light intensity at the edge of the light guide plate is I0×cos(α-90°).

2. The large-area direct-lit backlight module capable of compensating edge brightness according to claim 1, characterized in that: The direct-type backlight module includes a plurality of direct-type backlight sources, which are embedded in the center of the semi-ellipsoidal concave microstructure at the bottom of the light guide plate, and the area of ​​the direct-type backlight region occupies less than 60% of the area of ​​the light guide plate.

3. The large-area direct-lit backlight module capable of compensating edge brightness according to claim 2, characterized in that: The distances between two adjacent direct-type backlight sources are L and D respectively, and they are arranged in an n×m matrix. The area of ​​the applied display device is not less than 46 inches.

4. The large-area direct-lit backlight module capable of compensating edge brightness according to claim 1, characterized in that: A side rectangular coordinate system is established, the light source is placed on the zox plane, the light guide plate is placed on the yox plane, and the light propagates on the zoy plane. The side light illumination of the light guide plate satisfies the following formula: In the formula, E V Indicates the illuminance value at point P, at E V When the value is lower than 80%, an edge-type backlight is set to achieve edge compensation.

5. The large-area direct-lit backlight module capable of compensating edge brightness according to claim 1, characterized in that: The corner-entry backlight source, edge-entry backlight source and direct-lit backlight source use one or more of high-power 2835 lamp beads, 3528 lamp beads, 5050 lamp beads or 3535 lamp beads.

6. The large-area direct-lit backlight module capable of compensating edge brightness according to claim 1, characterized in that: Based on the brightness of the direct backlight area, the driving circuit of the edge backlight source is adjusted to make the full-screen brightness uniformity of the display device reach more than 80%.

7. The large-area direct-lit backlight module capable of compensating edge brightness according to claim 1, characterized in that: The material of the light guide plate is one or more of polymethyl methacrylate, polystyrene, cycloolefin polymer, cycloolefin copolymer, polycarbonate, and polydimethylphenylsiloxane.

8. The large-area direct-lit backlight module capable of compensating edge brightness according to claim 1, characterized in that: The edge of the light guide plate is surrounded by an edge reflector; the material of the edge reflector is one or more of polyethylene terephthalate, polyurethane resin, polycarbonate, polyethylene, and polymethyl methacrylate.

9. The large-area direct-lit backlight module capable of compensating edge brightness according to claim 1, characterized in that: The following steps are used for production: Step S1: manufacturing a light guide plate unit; Step S2: making a semi-ellipsoidal concave microstructure at the bottom of the light guide plate; performing a corner removal treatment on the light guide plate, grinding and polishing the four corners to form a flat light incident surface, so that the right-angled corner area of ​​the light guide plate becomes a flat corner area; Step S3: embedding a direct-lit backlight source at the center of the microstructure and facing the light guide plate; placing a corner-lit backlight source at the cross-section of the planar corner regions of the four corners of the light guide plate; Step S4: placing an edge-type backlight source at locations where the illumination on the four sides of the light guide plate is relatively low; Step S5: surround the edge of the light guide plate with an edge reflector to completely cover the corner-type backlight source and the edge-type backlight source; Step S5: adding a reflective sheet on the lower surface of the light guide plate to reflect the light transmitted from the bottom of the light guide plate to improve the utilization rate of the light source; Step S6: adding an optical film on the upper surface of the light guide plate, including a diffuser and an orthogonally placed prism film.

Images