Backlight flexible circuit board, backlight source, backlight module and liquid crystal display device

Abstract

The embodiment of the utility model relates to the technical field of display, and provides a backlight flexible circuit board, a backlight source, a backlight module and a liquid crystal display device. The backlight flexible circuit board comprises a main body part, a welding part and a bending part. The main body part is used for installing and electrically connecting a light-emitting element. The welding part is used for being electrically connected with the main flexible circuit board. The bending part is connected between the main body part and the welding part. The direction of the main body part pointing to the welding part is defined as a first direction. The bending portion is axially symmetric about the first direction. The bending part comprises a plurality of hollow quadrilateral structures, and each quadrilateral structure comprises a first diagonal line parallel to the first direction and a second diagonal line perpendicular to the first direction. Every two adjacent quadrilateral structures have a collinear diagonal line, and every two adjacent quadrilateral structures are overlapped at respective vertex angles to form a quadrilateral hollow part. The backlight flexible circuit board is favorable for improving the problem of local light leakage of a liquid crystal display device.

Description

Technical Field

[0001] The present application relates to the field of display technologies, and in particular, to a backlight flexible circuit board, a backlight source, a backlight module, and a liquid crystal display device. Background Art

[0002] A liquid crystal display device generally includes a liquid crystal module and a backlight module for providing backlight to the liquid crystal module. Among them, the backlight module includes a direct-lit backlight module and a side-lit backlight module. And the side-lit backlight module generally includes a back plate, a rubber frame, a light guide plate, and a backlight source. The backlight source includes a backlight flexible circuit board and a light-emitting element electrically connected to the backlight flexible circuit board. The light-emitting element is received in the accommodation space formed by the back plate and the rubber frame and is located on the light-incident side of the light guide plate. After the backlight flexible circuit board is fixed to the rubber frame by an adhesive, it is folded back to the side where the back plate is located and electrically connected to the main flexible circuit board of the liquid crystal display screen.

[0003] However, in the existing liquid crystal display device, the backlight flexible circuit board is likely to be separated from the rubber frame at the bonding position with the rubber frame, thereby causing the problem of local light leakage in the liquid crystal display device. Summary of the Utility Model

[0004] A first aspect of the present application provides a backlight flexible circuit board. The backlight flexible circuit board includes a main body portion, a welding portion, and a bending portion. The main body portion is used for mounting and electrically connecting the light-emitting element. The welding portion is used for electrically connecting with the main flexible circuit board so that the main flexible circuit board drives the light-emitting element to emit light. The bending portion is connected between the main body portion and the welding portion. The direction from the main body portion to the welding portion is defined as the first direction. The bending portion is axisymmetric about the first direction. The bending portion includes a plurality of hollow quadrilateral structures. Each quadrilateral structure includes a first diagonal line and a second diagonal line. The first diagonal line is parallel to the first direction. The second diagonal line is parallel to a second direction, and the second direction is perpendicular to the first direction. Each adjacent two quadrilateral structures have a collinear diagonal line, and each adjacent two quadrilateral structures intersect and overlap at one of their respective vertexes to form a quadrilateral hollow portion.

[0005] In the backlight flexible circuit board of the embodiment of the present application, the direction in which the main body points to the welding part is the first direction, and the bending part is symmetrical about the first direction. Compared with the S-shaped backlight flexible circuit board, the risk of welding deviation with the main flexible circuit board is lower. In addition, in the backlight flexible circuit board of the embodiment of the present application, the bending part includes a plurality of hollowed-out quadrilateral structures, each of which includes a first diagonal parallel to the first direction and a second diagonal perpendicular to the first direction, and each adjacent two quadrilateral structures have a collinear diagonal, and each adjacent two quadrilateral structures overlap at one of their respective apex angles and form a quadrilateral hollow part. As a result, the backlight flexible circuit board of the embodiment of the present application has certain elastic properties in both the first and second directions, so that the rebound force of the backlight flexible circuit board is decomposed and weakened during the backlight flexible circuit board folding welding process. In summary, the backlight flexible circuit board of the embodiment of the present application is conducive to reducing the risk of welding pulling and welding deviation, weakening the rebound force, and thus improving the problem that the backlight flexible circuit board is easily separated from the glue frame at the bonding point with the glue frame, which leads to local light leakage of the liquid crystal display device.

[0006] In some embodiments, each quadrilateral structure is a rhombus. Since the four sides of the rhombus are equal, the rhombus-shaped quadrilateral structure is symmetrical in both the first direction and the second direction. When the backlight flexible circuit board is subjected to external force or thermal expansion, the thermomechanical stress or stress will be evenly distributed along the edges of the rhombus, which is conducive to reducing stress concentration and the risk of potential material fatigue or cracking. In addition, due to the symmetrical shape of the rhombus, compared with quadrilaterals of other shapes, each quadrilateral structure Q is a rhombus, which is conducive to controlling the consistency of the hollow part, thereby improving production efficiency and the consistency of the backlight flexible circuit board.

[0007] In some embodiments, each quadrilateral structure includes a first side, a second side, a third side, and a fourth side connected in sequence, the first side and the second side are located on the side of the second diagonal line close to the main body, and the third side and the fourth side are located on the side of the second diagonal line away from the main body; the first side and the second side both have a first length, the third side and the fourth side both have a second length, and the first length is different from the second length; or, the first side and the fourth side both have a first length, the second side and the third side both have a second length, and the first length is different from the second length. Thus, sides of different lengths can provide different degrees of bending and flexibility, so that the backlight flexible circuit board can better adapt to irregular mounting surfaces or fine-tuning during the installation process. In addition, by adjusting the lengths of each side in the quadrilateral structure, the shape and function of the backlight flexible circuit board can be optimized according to specific application requirements and functional requirements, increasing the flexibility and diversity of the backlight flexible circuit board design.

[0008] In some embodiments, a plurality of quadrilateral structures are arranged along the first direction and / or the second direction, thereby facilitating increasing the flexibility and diversity of the backlight flexible circuit board design.

[0009] In some embodiments, along the second direction, the plurality of hollowed-out quadrilateral structures include two side portions located on opposite sides of the hollowed-out portion, the side portions include wiring, and the wiring is electrically connected to the main body portion and the welding portion. Thus, since each side portion is continuous in the first direction, by arranging wiring on both sides of the hollowed-out portion, the space of the backlight flexible circuit board can be more effectively utilized, and the wiring can also be more orderly.

[0010] In some embodiments, the bending portion further includes a first strip portion and a second strip portion. The first strip portion is connected between the main body and the plurality of hollowed-out quadrilateral structures. The second strip portion is connected between the welding portion and the plurality of hollowed-out quadrilateral structures. The opposite ends of the routing extend to the first strip portion and the second strip portion, respectively, to be electrically connected to the main body and the welding portion. Thus, by providing the first strip portion and the second strip portion, the connection strength of the bending portion of the backlight flexible circuit board at these connection positions can be enhanced.

[0011] In some embodiments, the backlight flexible circuit board further includes a first pad, a second pad and a protective layer, the protective layer covers the wiring and exposes the first pad and the second pad, the first pad is used for welding with the light-emitting element, and the second pad is used for welding with the main flexible circuit board. Thus, the protective layer covers the wiring, which is beneficial to prevent the wiring from being physically damaged or chemically corroded during manufacturing, assembly and use. The first pad and the second pad are used for welding with the light-emitting element and the main flexible circuit board respectively, which is beneficial to ensure the firmness and stability of the electrical connection and mechanical connection between the light-emitting element and the backlight flexible circuit board, and between the main flexible circuit board and the backlight flexible circuit board, and reduce the risk of poor contact.

[0012] The second aspect of the present application provides a backlight source, which includes the backlight flexible circuit board of the first aspect of the present application and a plurality of light-emitting elements, which are mounted on a main body and electrically connected to the main body.

[0013] The backlight source of the second aspect of the present application has at least the same advantages as the backlight flexible circuit board of the first aspect of the present application, which will not be described in detail.

[0014] The third aspect of the present application provides a backlight module. The backlight module includes a back plate, a plastic frame, a light guide plate, and the backlight source of the second aspect of the present application. The plastic frame is located on one side of the back plate and forms a storage space together with the back plate. The light guide plate is located in the storage space. The main body is connected to the side of the plastic frame away from the back plate, and the light-emitting element is located in the storage space and on the light incident side of the light guide plate.

[0015] The backlight module of the third aspect of the present application has at least the same advantages as the backlight source of the second aspect of the present application, which will not be described in detail.

[0016] The fourth aspect of the present application provides a liquid crystal display device. The liquid crystal display device includes the backlight module of the third aspect of the present application and a liquid crystal module. The liquid crystal module and the backlight module are stacked. The liquid crystal module includes a display panel and a main flexible circuit board. The display panel is located on the side of the light guide plate away from the back plate. The main flexible circuit board is electrically connected to the display panel and bent to the side of the back plate away from the display panel. The bent portion is bent so that the welding portion is welded to the main flexible circuit board on the side of the back plate away from the display panel.

[0017] The liquid crystal display device of the fourth aspect of the present application has at least the same advantages as the backlight module of the third aspect of the present application, which will not be elaborated here. Description of the Drawings

[0018] Figure 1 It is an analysis diagram of the reason for light leakage in the liquid crystal display device in the related art.

[0019] Figure 2 It is a schematic diagram of the electrical connection between the backlight flexible circuit board and the main flexible circuit board in the related art.

[0020] Figure 3 It is a schematic diagram of two different structures of the backlight flexible circuit board in the related art.

[0021] Figure 4 It is a plan view schematic diagram of the liquid crystal display device according to an embodiment of the present application.

[0022] Figure 5 For Figure 4 A schematic cross-sectional view along the V-V line.

[0023] Figure 6 For Figure 5 Another plan view schematic diagram of the liquid crystal display device in

[0024] Figure 7 For Figure 5 A schematic diagram of the structure of the backlight flexible circuit board in

[0025] Figure 8 For Figure 7 Schematic diagrams of the bent portion of the backlight flexible circuit board in

[0026] Main Component Symbol Explanation:

[0027] Liquid crystal display device 100, 100’

[0028] Liquid crystal module 10, 10’

[0029] Display panel 11

[0030] Cover plate 111

[0031] Optical glue layer 112

[0032] Upper polarizer 113

[0033] Color filter substrate 114

[0034] Liquid crystal layer 115

[0035] Thin film transistor array substrate 116

[0036] Lower polarizer 117

[0037] Main flexible circuit boards 12, 12’

[0038] Backlight modules 20, 20’

[0039] Backplates 21, 21’

[0040] Bottom plate 211

[0041] Front side 211a

[0042] Back side 211b

[0043] Side plates 212

[0044] Adhesive frames 22, 22’

[0045] Light guide plates 23, 23’

[0046] Backlights 24, 24’

[0047] Backlight flexible circuit boards 241, 241’, 241a’, 241b’

[0048] Base material layer 241a

[0049] Traces 241b

[0050] Protective layer 241c

[0051] Solder pads P1’, P2’

[0052] First solder pad P1

[0053] Second solder pad P2

[0054] Third solder pad P3

[0055] Main body part 2411

[0056] Bending part 2412

[0057] Quadrilateral structure Q

[0058] First quadrilateral structure Q1

[0059] Second quadrilateral structure Q2

[0060] First sides S11, S21

[0061] Second sides S12, S22

[0062] Third sides S13, S23

[0063] Fourth sides S14, S24

[0064] Display area AA

[0065] Border area NA

[0066] First strip portion 2412a

[0067] Second strip portion 2412b

[0068] First diagonal line L1

[0069] Second diagonal line L2

[0070] Hollow-out portion H

[0071] First hollow-out portion H1

[0072] Second hollow-out portion H2

[0073] Third hollow-out portion H3

[0074] Welding portion 2413

[0075] Light-emitting elements 242, 242’

[0076] Adhesive layers 25, 25’

[0077] Optical film stack 26

[0078] Reflective sheet 261

[0079] Diffusion sheet 262

[0080] Lower brightness enhancement film 263

[0081] Upper brightness enhancement film 264

[0082] Adhesive layer 30

[0083] First direction D1

[0084] Second direction D2

[0085] Third direction D3

[0086] Accommodating spaces R, R’ Detailed implementation manners

[0087] Figure 1 It is an analysis diagram of the light leakage reason of a liquid crystal display device in the related art. AsFigure 1 As shown in Figure (a) in Figure 1 , the backlight module 20' is a side-injection backlight module. The backlight module 20' includes a backplane 21', a rubber frame 22', a light guide plate 23', a backlight source 24' and an adhesive layer 25'.

[0088] The backplane 21' and the rubber frame 22' form an accommodation space R'. The light guide plate 23' is located in the accommodation space R'. The backlight source 24', or the light bar, includes a backlight flexible circuit board 241' and light-emitting elements 242' electrically connected to the backlight flexible circuit board 241'. The light-emitting elements 242' are located within the accommodation space R'. The light emitted by the light-emitting elements 242' is converted from a line light source into a surface light source through the dot patterns of the light guide plate 23', and then the point light sources at each position are homogenized through each layer of film material, and the light brightness is increased. Finally, the liquid crystal module 10' is driven by the electric field generated by the electric signal to drive the liquid crystal to rotate at different angles to present different light transmittances, achieving the display effect.

[0089] Figure 2 Schematic diagram of the electrical connection between the backlight flexible circuit board and the main flexible circuit board in the related art. Please refer to Figure 1 and Figure 2 , after the backlight flexible circuit board 241' is fixed to the rubber frame 22' through the adhesive layer 25' (such as lamp glue), it is folded back to the side of the backplane 21' away from the liquid crystal module 10' and is electrically connected (such as welded) to the main flexible circuit board 12' of the liquid crystal module 10'.

[0090] Specifically, pads P1' are provided on the backlight flexible circuit board 241', and pads P2' are provided on the main flexible circuit board 12'. After the pads P1' and the pads P2' are welded correspondingly, the main flexible circuit board 12' can drive the light-emitting elements 242' to emit light. However, as the lower border design of the liquid crystal display device 100' (such as a mobile phone) becomes narrower and narrower, the overlapping width between the adhesive layer 25' and the rubber frame 22' decreases, and the adhesion between the adhesive layer 25' and the rubber frame 22' decreases. Moreover, due to the rebound force existing after the backlight flexible circuit board 241' of the backlight source 24' is folded back, when the adhesion between the adhesive layer 25' and the rubber frame 22' is less than the above-mentioned rebound force, the adhesive layer 25' peeling phenomenon occurs, causing the light-emitting surface of the light-emitting elements 242' to be misaligned with the light guide plate 23' in the backlight module 20', and then resulting in a single-point light leakage due to the change of the light path, affecting the user experience. Therefore, reducing the rebound force of the backlight flexible circuit board 241' has a positive effect on reducing the single-point light leakage of the liquid crystal display device 100'.

[0091] In addition, during the operation of welding the backlight flexible circuit board 241' of the backlight source 24' to the main flexible circuit board 12' of the liquid crystal module 10', pulling or misalignment during welding by the operator may also cause a certain degree of peeling of the adhesive layer 25', resulting in single-point light leakage.

[0092] The following refers to Figure 3 two different structures of backlight flexible circuit boards in the related art. As Figure 3 shown in Figure (a) therein, the backlight flexible circuit board 241a' is of I-type design. The lead-out end of the backlight flexible circuit board 241a' is vertically bent to the side of the back plate 21' facing away from the liquid crystal module, and is welded to the main flexible circuit board 12' of the liquid crystal module.

[0093] As Figure 3 shown in Figure (b) therein, the backlight flexible circuit board 241b' is of S-type design. There is a span between the left and right of the backlight flexible circuit board 241b', and it is bent in an S shape to the side of the back plate 21' facing away from the liquid crystal module and welded to the main flexible circuit board 12'.

[0094] Specifically, there is a large rebound stress after the backlight flexible circuit board 241a' and the backlight flexible circuit board 241b' are bent. Among them, the rebound force of the I-type designed backlight flexible circuit board 241a' is greater than that of the S-type designed backlight flexible circuit board 241b'. The rebound force acts on the back plate 21' (usually an iron frame), aggravating the reverse warping deformation of the back plate 21'. And, according to the principle of action and reaction, the lead-out position of the backlight flexible circuit board is affected by the rebound force, causing the adhesive layer 25' to separate from the rubber frame 22', resulting in local light leakage of the liquid crystal display device 100'. In addition, for the S-type designed backlight flexible circuit board 241b', there is a problem of welding misalignment due to the asymmetric design.

[0095] In summary, it is necessary to develop a backlight flexible circuit board that reduces the rebound force of the backlight flexible circuit board and at the same time avoids welding pulling and welding misalignment, so as to avoid the peeling of the adhesive layer at the lead-out position of the backlight flexible circuit board, resulting in local light leakage of the liquid crystal display device.

[0096] The following specifically describes the backlight flexible circuit board, backlight source, backlight module and liquid crystal display device of the embodiments of the present application with reference to the accompanying drawings.

[0097] Figure 4 is a schematic plan view of a liquid crystal display device according to an embodiment of the present application. As Figure 4 shown, in this embodiment, the liquid crystal display device 100 is a mobile phone. In other embodiments, the liquid crystal display device may also be a tablet computer, a notebook computer, etc.

[0098] Specifically, the liquid crystal display device 100 includes a display area AA and a border area NA. The display area AA is used for displaying images. The border area NA is disposed around the display area AA. In this embodiment, the display area AA is generally rectangular in shape.

[0099] For convenience of description hereinafter, the length direction (or the up-and-down direction) of the liquid crystal display device 100 is defined as the first direction D1, the width direction (or the left-and-right direction) of the liquid crystal display device 100 is defined as the second direction D2, and the thickness direction of the liquid crystal display device 100 is defined as the third direction D3. In this embodiment, the first direction D1, the second direction D2, and the third direction D3 are perpendicular to each other pairwise.

[0100] Figure 5 It is Figure 4 a schematic cross-sectional view along the V-V line. As Figure 5 shown, the liquid crystal display device 100 includes a liquid crystal module 10, a backlight module 20, and an adhesive layer 30. The backlight module 20 is stacked on the side of the liquid crystal module 10 facing away from the display screen to provide the backlight required for display to the liquid crystal module 10. The liquid crystal module 10 and the backlight module 20 are bonded by the adhesive layer 30. The adhesive layer 30 is located in the border area NA.

[0101] The adhesive layer 30 is, for example, a light-shielding adhesive layer to bond the liquid crystal module 10 and the backlight module 20 while preventing the light of the backlight module 20 from leaking into the border area NA. In other embodiments, the boundary between the border area NA and the display area AA is not limited to the contour of the adhesive layer 30.

[0102] Specifically, the liquid crystal module 10 includes a display panel 11. The display panel 11 includes a cover plate 111, an optical adhesive layer 112, an upper polarizer 113, a color filter substrate 114, a liquid crystal layer 115, a thin film transistor array substrate 116, and a lower polarizer 117 that are sequentially stacked in the third direction D3.

[0103] The cover plate 111 is bonded to the upper polarizer 113 through the optical adhesive layer 112. The cover plate 111 is, for example, transparent glass or transparent plastic to protect the components located below it. The optical adhesive layer 112 is, for example, a transparent optical adhesive. The transmission axes of the upper polarizer 113 and the lower polarizer 117 are perpendicular to each other. The upper polarizer 113 and the lower polarizer 117 are used to filter and control the direction of light so that the arrangement of the liquid crystal molecules in the liquid crystal layer 115 can effectively control the passage of light, thereby forming an image.

[0104] The color filter substrate 114 may include red, green, and blue filter units so that the liquid crystal display device 100 can display full-color images. The thin-film transistor array substrate 116 is used to provide independent switching control for each pixel to ensure that each pixel can respond to input signals. The liquid crystal layer 115 is located between the color filter substrate 114 and the thin-film transistor array substrate 116. The liquid crystal molecules in the liquid crystal layer 115 are used to change the alignment state under the action of an electric field, thereby controlling the passage or blocking of light.

[0105] In some embodiments, the components in the display panel 11 are not limited to Figure 5 those shown. For example, the display panel 11 may further include a touch screen, which may be located between the cover plate 111 and the upper polarizer 113 so that the liquid crystal display device 100 can implement a touch function.

[0106] The backlight module 20 includes a backplane 21, a rubber frame 22, a light guide plate 23, a backlight source 24, an adhesive layer 25, and an optical film group 26.

[0107] The rubber frame 22 is located on the side of the backplane 21 close to the display panel 11. The backplane 21 and the inner wall of the rubber frame 22 together form an accommodation space R. The light guide plate 23 is located in the accommodation space R and between the backplane 21 and the display panel 11. The backlight source 24 includes a backlight flexible circuit board 241 and a light-emitting element 242. The light-emitting element 242 is mounted on the backlight flexible circuit board 241 and is electrically connected to the backlight flexible circuit board 241. The backlight flexible circuit board 241 is bonded to the rubber frame 22 through the adhesive layer 25 and is bent to the side of the backplane 21 away from the display panel 11. The optical film group 26 is located in the accommodation space R and between the backplane 21 and the display panel 11.

[0108] Specifically, the backplane 21 includes a bottom plate 211 and side plates 212. The bottom plate 211 is generally rectangular, and the side plates 212 are connected to the bottom plate 211 and extend toward the side where the display panel 11 is located.

[0109] The material of the backplane 21 is, for example, metal to facilitate the heat dissipation of the backlight module 20. The material of the backplane 21 can also be a non-metal plate to reduce the weight of the liquid crystal display device 100. The bottom plate 211 and the side plates 212 may be integrally formed, but are not limited thereto.

[0110] More specifically, the bottom plate 211 includes opposite front surfaces 211a and back surfaces 211b. The front surface 211a is closer to the display panel 11 than the back surface 211b. The rubber frame 22 is located on the side where the front surface 211a of the bottom plate 211 is located and in the border area NA. The rubber frame 22 is generally in a mouth shape (or a rectangular frame). The rubber frame 22 and the bottom plate 211 enclose to form the accommodation space R.

[0111] The optical film stack 26 includes a reflective sheet 261, a diffusion sheet 262, a lower brightness enhancement sheet 263, and an upper brightness enhancement sheet 264 that are sequentially stacked in the third direction D. Specifically, the reflective sheet 261 is located between the bottom plate 211 and the light guide plate 23. The light guide plate 23, the diffusion sheet 262, the lower brightness enhancement sheet 263, and the upper brightness enhancement sheet 264 are arranged corresponding to the display area AA approximately. There is a gap between the light guide plate 23 and the rubber frame 22. The light-emitting elements 242 of the backlight 24 are located in this gap and on the light-incident side of the light guide plate 23.

[0112] In this embodiment, the rubber frame 22 and the side plate 212 are respectively provided with avoiding grooves. After the backlight flexible circuit board 241 passes through the avoiding grooves on the rubber frame 22 and the side plate 212 in sequence, it is bent and extends along the side plate 212 to the back surface 211b of the bottom plate 211.

[0113] The light-emitting elements 242 can be inorganic light-emitting diodes, but are not limited thereto.

[0114] Specifically, the backlight flexible circuit board 241 includes a main body portion 2411, a bending portion 2412, and a welding portion 2413. The bending portion 2412 is connected between the main body portion 2411 and the welding portion 2413. The light-emitting elements 242 are mounted on the main body portion 2411 and are electrically connected to the main body portion 2411. The main body portion 2411 is connected to the side of the rubber frame 22 facing away from the back plate 21 through an adhesive layer 25. The bending portion 2412 is bent so that the welding portion 2413 is bent to the side of the back plate 21 facing away from the display panel 11.

[0115] Figure 6 For Figure 5 Another planar schematic diagram of the liquid crystal display device in. As Figure 6 shown, the liquid crystal module 10 further includes a main flexible circuit board 12. The main flexible circuit board 12 is located on the side of the back plate 21 facing away from the display panel 11 (or on the side where the back surface 211b of the bottom plate 211 is located). The main flexible circuit board 12 is electrically connected to the display panel 11 to drive the display panel 11 to display an image. The welding portion 2413 is bent to the side where the back surface 211b of the bottom plate 211 is located and is electrically connected to the main flexible circuit board 12, so that the main flexible circuit board 12 drives the light-emitting elements 242 to emit light.

[0116] Figure 7 For Figure 5 The structural schematic diagram of the backlight flexible circuit board in. Please refer to Figure 5 、 Figure 6 And Figure 7 , the main body portion 2411 extends in the second direction D2 and is generally strip-shaped. The bending portion 2412 is connected to one side of the main body portion 2411 in the first direction D1. The bending portion 2412 is axisymmetric about the first direction D1.

[0117] The bent portion 2412 includes a plurality of hollow quadrilateral structures Q. Adjacent quadrilateral structures Q intersect at their respective vertex angles. In this embodiment, the number of the hollow quadrilateral structures Q is two. The two hollow quadrilateral structures Q are arranged along the first direction D1.

[0118] For the convenience of description hereinafter, among the two hollow quadrilateral structures Q, the quadrilateral structure Q close to the main body portion 2411 is defined as the first quadrilateral structure Q1, and the quadrilateral structure Q close to the welding portion 2413 is defined as the second quadrilateral structure Q2.

[0119] Specifically, the first quadrilateral structure Q1 and the second quadrilateral structure Q2 intersect at one of their respective vertex angles to form three hollow portions H. Among them, the three hollow portions H are respectively the first hollow portion H1 in the shape of a quadrilateral, the second hollow portion H2 in the shape of a V, and the third hollow portion H3 in the shape of a V. Among them, the opening directions of the Vs of the second hollow portion H2 and the third hollow portion H3 are opposite.

[0120] The bent portion 2412 further includes a first strip portion 2412a and a second strip portion 2412b. Both the first strip portion 2412a and the second strip portion 2412b are substantially in the shape of a rectangular strip. The first strip portion 2412a is connected between the main body portion 2411 and the plurality of quadrilateral structures Q. The second strip portion 2412b is connected between the welding portion 2413 and the plurality of quadrilateral structures Q. Thus, by providing the first strip portion 2412a at the position where the bent portion 2412 is electrically connected to the main body portion 2411 and providing the second strip portion 2412b at the position where the bent portion 2412 is electrically connected to the welding portion 2413, the connection strength of the backlight flexible circuit board 241 at these connection positions can be enhanced.

[0121] Specifically, the main body portion 2411, the bent portion 2412 and the welding portion 2413 all include a flexible base material layer 241a. Among them, the base material layers 241a in the main body portion 2411, the bent portion 2412 and the welding portion 2413 can be integrally formed.

[0122] The main body portion 2411 further includes a first pad P1 located on the base material layer 241a. A plurality of first pads P1 are arranged at intervals along the second direction D2. Each pair of first pads P1 is used for welding a light-emitting element 242 correspondingly. Thus, it is beneficial to ensure the firmness and stability of the electrical connection and mechanical connection between the light-emitting element 242 and the backlight flexible circuit board 241, and reduce the risk of poor contact.

[0123] The bent portion 2412 further includes a plurality of traces 241b located on the base material layer 241a. The traces 241b are electrically connected to both the main body portion 2411 and the welding portion 2413.

[0124] Specifically, along the second direction D2, the two hollow quadrilateral structures Q include two side portions located on opposite sides of the three hollow portions H. The side portions include the above-mentioned trace 241b. Or rather, the trace 241b is disposed in the area where the side portions are located. The opposite ends of the trace 241b respectively extend to the first strip portion 2412a and the second strip portion 2412b to be electrically connected to the main body portion 2411 and the welding portion 2413.

[0125] Thus, since each side portion is continuous in the first direction D1, by disposing the trace 241b on the side portions on both sides of the hollow portion H, the space of the backlight flexible circuit board 241 can be utilized more effectively, and at the same time, the wiring is made more orderly. Although the portion of the bending portion 2412 located between the two side portions (or rather, the quadrilateral portion enclosing the first hollow portion H1) is discontinuous in the first direction D1, it can provide the necessary structural strength for the backlight flexible circuit board 241 through its geometric shape; moreover, this discontinuous structure is conducive to providing better space for the backlight flexible circuit board 241 to stretch and deform.

[0126] The welding portion 2413 further includes a plurality of second pads P2 located on the substrate layer 241a. The plurality of second pads P2 are arranged at intervals along the second direction D2. The main flexible circuit board 12 includes a plurality of third pads P3 arranged at intervals along the second direction D2. The plurality of second pads P2 are welded to the plurality of third pads P3 in one-to-one correspondence. Thus, it is beneficial to ensure the firmness and stability of the electrical connection and mechanical connection between the main flexible circuit board 12 and the backlight flexible circuit board 241, and reduce the risk of poor contact.

[0127] The backlight flexible circuit board 241 further includes a protective layer 241c. The protective layer 241c covers the trace 241b and exposes the first pad P1 and the second pad P2. The protective layer 241c can be, but is not limited to, a solder mask layer.

[0128] Figure 8 For Figure 7 the schematic diagrams of the bending portion of the backlight flexible circuit board in different states. Among them, Figure 8 the figures (a) and (b) in

[0129] Please refer to Figure 7 and Figure 8 , the first quadrilateral structure Q1 includes a first diagonal line L11 parallel to the first direction D1 and a second diagonal line L12 parallel to the second direction D2. The second quadrilateral structure Q2 includes a first diagonal line L21 parallel to the first direction D1 and a second diagonal line L22 parallel to the second direction D2. The first diagonal line L11 and the first diagonal line L21 are collinear.

[0130] The first quadrilateral structure Q1 includes a first side S11, a second side S12, a third side S13, and a fourth side S14 connected in sequence. The first side S11 and the second side S12 are located on one side of the second diagonal L12 close to the main body portion 2411, and the third side S13 and the fourth side S14 are located on the side of the second diagonal L12 away from the main body portion 2411.

[0131] The second quadrilateral structure Q2 includes a first side S21, a second side S22, a third side S23, and a fourth side S24 connected in sequence. The first side S21 and the second side S22 are located on one side of the second diagonal L22 close to the main body portion 2411, and the third side S23 and the fourth side S24 are located on the side of the second diagonal L22 away from the main body portion 2411.

[0132] The third side S13 of the first quadrilateral structure Q1 and the second side S22 of the second quadrilateral structure Q2 form an X-shaped intersection. The fourth side S14 of the first quadrilateral structure Q1 and the first side S21 of the second quadrilateral structure Q2 form an X-shaped intersection. Thus, while ensuring that the backlight flexible circuit board 241 has good bending flexibility, it is also beneficial to ensure the overall structural strength of the backlight flexible circuit board 241.

[0133] The third side S13 and the fourth side S14 of the first quadrilateral structure Q1 overlap with the first side S21 and the second side S22 of the second quadrilateral structure Q2 to form a first hollow portion H1. Among the two diagonals of the first hollow portion H1, one is collinear with the first diagonal L11 and the first diagonal L21, and the other is parallel to the second diagonal L12 and the second diagonal L22.

[0134] In this embodiment, each quadrilateral structure Q is a rhombus, and the sizes of each quadrilateral structure Q are the same. Hereinafter, the two quadrilateral structures Q in this embodiment are also referred to as a double-rhombus overlapping structure.

[0135] Specifically, the double-rhombus overlapping structure is symmetric about the first diagonal L11 (or the first diagonal L21). The main body portion 2411 and the welding portion 2413 are respectively located at both ends of the double-rhombus overlapping structure. The main body portion 2411 and the welding portion 2413 are connected through the traces 241b on both sides of the double rhombus, and the number and arrangement of the traces 241b can be selected according to needs.

[0136] As Figure 8 shown in FIGS. (a) and (b), the double-rhombus overlapping structure has a certain stretching and shrinking performance in both the first direction D1 and the second direction D2.

[0137] Specifically, the telescopic performance of the backlight flexible circuit board 241 in the first direction D1 can effectively weaken the influence of the pulling of the backlight flexible circuit board 241 on the reverse warping of the backplane 21 during the folding and soldering process of the backlight flexible circuit board 241. The telescopic performance of the backlight flexible circuit board 241 in the second direction D2 is beneficial to preventing the backlight flexible circuit board 241 from being torn, thereby avoiding the occurrence of an open circuit in the backlight flexible circuit board 241 and disconnecting the backlight module 20 from the liquid crystal module 10.

[0138] In addition, the resilience of the backlight flexible circuit board 241 is decomposed and weakened along the two sides of the rhombus (as shown in Figure 8 for decomposition along the third side S23 and the fourth side S24), which greatly reduces the force transmitted to the end of the wire outlet, thereby preventing light leakage of the liquid crystal display device caused by the separation of the adhesive layer 25 under stress. In addition, compared with the S-shaped backlight flexible circuit board, in the backlight flexible circuit board 241, the double-rhombus overlapping structure is a left-right symmetric structure, and the risk of welding deviation is lower.

[0139] Therefore, the backlight flexible circuit board 241 is beneficial to achieving the purpose of weakening the resilience, reducing the welding pull and the risk of welding deviation, and further improving the problem that the backlight flexible circuit board is prone to separation from the rubber frame at the bonding part with the rubber frame, resulting in local light leakage of the liquid crystal display device.

[0140] In addition, the setting of the hollow part H is beneficial to reducing the rigidity of the backlight flexible circuit board 241 at the bending part 2412, making the bending part 2412 more conducive to bending. Moreover, the hollow part H can also provide more air circulation space, which helps the thermal management of the backlight flexible circuit board 241 and avoids the overheating problem that may occur when the light-emitting element 242 works for a long time. In addition, the setting of the hollow part H is also beneficial to reducing the overall weight of the backlight flexible circuit board 241, and further beneficial to improving the light weight and portability of the liquid crystal display device 100.

[0141] In this embodiment, since the four sides of the rhombus are equal, the quadrilateral structure Q of the rhombus is symmetric in both the first direction D1 and the second direction D2. When the backlight flexible circuit board 241 is subjected to external force or thermal expansion, the thermomechanical stress or stress will be evenly distributed along each side of the rhombus, which is beneficial to reducing stress concentration and the risk of potential material fatigue or rupture.

[0142] In other embodiments, the number of the quadrilateral structures Q in the bending portion 2412 may be more than two. Each quadrilateral structure Q includes a first diagonal parallel to the first direction D1 and a second diagonal perpendicular to the first direction D1. Each adjacent pair of quadrilateral structures Q has a collinear diagonal, and each adjacent pair of quadrilateral structures Q intersects and overlaps at one of their respective vertices to form a quadrilateral hollow portion H. In this case, compared with quadrilaterals of other shapes, each quadrilateral structure Q is a rhombus, which is beneficial to controlling the consistency of the hollow portion H, thereby improving the production efficiency and the consistency of the backlight flexible circuit board.

[0143] In some embodiments, multiple quadrilateral structures Q in the bending portion 2412 may be arranged along the second direction D2; alternatively, multiple quadrilateral structures Q in the bending portion 2412 may include at least two arranged along the first direction D1 and at least two arranged along the second direction D2. Among them, the arrangement manner of the multiple quadrilateral structures Q can be adjusted according to specific application requirements to provide greater design flexibility and functional diversity.

[0144] In other embodiments, the shapes of each quadrilateral structure Q are the same, but are not limited to being rhombuses. Specifically, in each quadrilateral structure Q, the four sides may have two lengths. Taking the first quadrilateral structure Q1 as an example, the first side S11 and the second side S12 may both have a first length, and the third side S13 and the fourth side S14 may both have a second length, but the first length and the second length are different. Specifically, the first length may be greater than the second length or less than the second length.

[0145] Thus, the sides of different lengths can provide different degrees of bending and flexibility, enabling the backlight flexible circuit board 241 to better adapt to an irregular mounting surface or fine-tuning during the mounting process. In addition, by adjusting the lengths of the respective sides in the quadrilateral structure Q, the shape and function of the backlight flexible circuit board 241 can be optimized according to specific application requirements and functional requirements, increasing the design flexibility and diversity of the backlight flexible circuit board 241.

[0146] In the backlight flexible circuit board according to the embodiment of the present application, the direction from the main body portion to the welding portion is the first direction, and the bending portion is axisymmetric about the first direction. Compared with the backlight flexible circuit board designed in an S shape, the risk of welding offset with the main flexible circuit board is lower.

[0147] In addition, in the backlight flexible circuit board according to the embodiment of the present application, the arrangement of multiple hollow quadrilateral structures in the bending portion enables the backlight flexible circuit board according to the embodiment of the present application to have a certain telescopic performance in both the first direction and the second direction, and further weakens the rebound force of the backlight flexible circuit board during the process of reverse folding and welding.

[0148] In summary, the backlight flexible circuit board of the embodiment of the present application is conducive to achieving the purpose of reducing the risks of welding pulling and welding offset and weakening the rebound force, thereby improving the problem that the backlight flexible circuit board is easily separated from the rubber frame at the bonding position with the rubber frame, resulting in local light leakage in the liquid crystal display device.

[0149] The above embodiments are only used to illustrate the technical solutions of the present application and not to limit them. Although the present application has been described in detail with reference to the above preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present application can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present application.

Claims

1. A backlight flexible circuit board, characterized in that, include: The main body is used for mounting and electrically connecting the light emitting element; A welding portion, used to be electrically connected to a main flexible circuit board, so that the main flexible circuit board drives the light-emitting element to emit light; as well as A bending portion connected between the main body portion and the welding portion; Among them, the direction in which the main body portion points to the welding portion is defined as a first direction, the bending portion is axially symmetrical about the first direction, the bending portion includes a plurality of hollow quadrilateral structures, each of the quadrilateral structures includes a first diagonal and a second diagonal, the first diagonal is parallel to the first direction, the second diagonal is parallel to the second direction, the second direction is perpendicular to the first direction, every two adjacent quadrilateral structures have a colinear diagonal, and every two adjacent quadrilateral structures overlap at one of their respective vertices to form a quadrilateral hollow portion.

2. The backlight flexible circuit board according to claim 1, wherein Each of the quadrilateral structures is a rhombus.

3. The backlight flexible circuit board according to claim 1, wherein Each of the quadrilateral structures comprises a first side, a second side, a third side and a fourth side connected in sequence, wherein the first side and the second side are located on a side of the second diagonal line close to the main body, and the third side and the fourth side are located on a side of the second diagonal line away from the main body; The first side and the second side both have a first length, the third side and the fourth side both have a second length, and the first length is different from the second length; or, the first side and the fourth side both have a first length, the second side and the third side both have a second length, and the first length is different from the second length.

4. The backlight flexible circuit board according to claim 2 or 3, characterized in that, The plurality of quadrilateral structures are arranged along the first direction and / or the second direction.

5. The backlight flexible circuit board according to claim 4, wherein, Along the second direction, the plurality of hollowed-out quadrilateral structures include two side portions located on opposite sides of the hollowed-out portion, the side portions include wiring, and the wiring is electrically connected to the main body portion and the welding portion.

6. The backlight flexible circuit board according to claim 5, wherein, The bending portion also includes a first strip portion and a second strip portion; the first strip portion is connected between the main body portion and the multiple hollow quadrilateral structures; the second strip portion is connected between the welding portion and the multiple hollow quadrilateral structures; the opposite ends of the routing line extend to the first strip portion and the second strip portion respectively to be electrically connected to the main body portion and the welding portion.

7. The backlight flexible circuit board according to claim 5, wherein The backlight flexible circuit board also includes a first pad, a second pad and a protective layer, the protective layer covers the trace and exposes the first pad and the second pad, the first pad is used for welding with the light emitting element, and the second pad is used for welding with the main flexible circuit board.

8. A backlight, characterized in that, include: The backlight flexible circuit board according to any one of claims 1 to 7; as well as A plurality of light emitting elements are mounted on the main body and electrically connected to the main body.

9. A backlight module, characterized in that, include: Back panel; A plastic frame, located at one side of the back plate and forming a receiving space together with the back plate; A light guide plate, located in the accommodation space; as well as According to the backlight source as described in claim 8, the main body is connected to a side of the plastic frame facing away from the back plate, and the light-emitting element is located in the accommodating space and on the light incident side of the light guide plate.

10. A liquid crystal display device, characterized in that, include: The backlight module as claimed in claim 9; as well as A liquid crystal module is stacked with the backlight module, the liquid crystal module includes a display panel and a main flexible circuit board, the display panel is located on the side of the light guide plate away from the back plate, the main flexible circuit board is electrically connected to the display panel and bent to the side of the back plate away from the display panel, the bent portion is bent so that the welding portion is welded to the main flexible circuit board on the side of the back plate away from the display panel.

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