Backlight module and display device

Abstract

The application discloses a backlight module and a display device, which comprise a back plate, a flexible circuit board, a light guide plate, a light source and an expansion gasket. The back plate has a containing cavity. The flexible circuit board is at least partially located in the containing cavity and is arranged close to the bottom of the containing cavity. The light guide plate is partially located in the containing cavity and is fixed on the flexible circuit board. The light source is located on the flexible circuit board in the containing cavity and is arranged close to the side of the light guide plate. The expansion gasket is located in the containing cavity and is located on the side of the light guide plate away from the flexible circuit board. In a first temperature range, the expansion gasket is in an expanded state, and the distance between the expansion gasket and the light guide plate is greater than or equal to 0 and less than a preset threshold. The application can effectively solve the problem of TST light shadow defects caused by the folding of the flexible circuit board while ensuring that the light guide plate and the light source can be assembled.

Description

Technical Field

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

[0002] Typically, a liquid crystal display (LCD) includes components such as a backlight module and a liquid crystal display panel, with the liquid crystal display panel located on the light-emitting side of the backlight module. The backlight module includes components such as a light source, a light guide plate, and an optical film assembly, used to output a backlight source for the liquid crystal display panel to display images.

[0003] Figure 1 This is a common type of edge-lit backlight module for liquid crystal displays, such as Figure 1 As shown, the side-lit backlight module 1 includes a backplate 2, a flexible printed circuit (FPC) 3, a first reflective layer 4, a light source 5, a light guide plate 6, an optical film assembly 7, and a second reflective layer 8. For the integrated light guide structure, the light source 5 and the light guide plate 6 are first bonded together with double-sided adhesive, and then assembled together into the U-fold structure of the backplate. To ensure that the integrated light guide structure can be assembled into the U-fold structure of the backplate, a certain gap needs to be reserved between the light guide plate 6 and the second reflective layer 8. However, during the TST (thermal shock test), the integrated light guide structure is prone to TST shadow defects, which are usually caused by wrinkles in the flexible printed circuit board 3 during the TST process.

[0004] To improve the TST (Light Guided Transmission) lighting problem, a common practice is to minimize the gap between the light guide plate 6 and the second reflective layer 8, thus limiting the degree of wrinkling in the flexible circuit board 3. However, to ensure the assemblability of the integrated light guide structure, the gap between the light guide plate 6 and the second reflective layer 8 cannot be infinitely small. Given this limitation, the TST lighting problem is difficult to completely and thoroughly resolve. Summary of the Invention

[0005] This application provides a backlight module and display device that can effectively solve the problem of poor TST light shadow caused by wrinkles in flexible circuit boards while ensuring the assemblability of the light guide plate and the light source.

[0006] This application provides a backlight module, including:

[0007] Back plate, with receiving cavity;

[0008] A flexible circuit board is located at least partially within the receiving cavity and is disposed near the bottom of the receiving cavity;

[0009] The light guide plate is partially located within the receiving cavity and fixed to the flexible circuit board;

[0010] A light source is located within the receiving cavity and on the flexible circuit board; the light source is positioned on the side near the light guide plate.

[0011] An expansion pad is located within the receiving cavity and on the side of the light guide plate away from the flexible circuit board;

[0012] Within the first temperature range, the expansion pad is in an expanded state, and the distance between the expansion pad and the light guide plate is greater than or equal to 0 and less than a preset threshold.

[0013] Optionally, within the second temperature range, the expansion pad is in its initial state, and the distance between the expansion pad and the light guide plate is greater than or equal to the preset threshold; any temperature in the first temperature range is higher than the temperature in the second temperature range.

[0014] Optionally, the expansion pad includes a first sub-pad and a second sub-pad with different expansion rates; the first sub-pad is located on the side of the second sub-pad away from the light guide plate, and the second sub-pad is located between the first sub-pad and the light guide plate;

[0015] The first sub-wafer includes a first serrated structure disposed near the second sub-wafer, and the second sub-wafer includes a second serrated structure disposed near the first sub-wafer, wherein the first serrated structure and the second serrated structure are toothed together.

[0016] Within the first temperature range, at least one of the first sub-gasket and the second sub-gasket can expand in the length direction of the expansion gasket, and during the expansion process, the contact area between the first serrated structure and the second serrated structure gradually decreases.

[0017] Optionally, within the first temperature range, at least one of the first sub-gasket and the second sub-gasket may also expand in the thickness direction of the expansion gasket.

[0018] Optionally, the first sawtooth structure includes a plurality of first sawtooth units arranged sequentially along a first direction, and the second sawtooth structure includes a plurality of second sawtooth units arranged sequentially along the first direction; the plurality of first sawtooth units and the plurality of second sawtooth units are toothed to each other, and each first sawtooth unit is in contact with a corresponding second sawtooth unit.

[0019] Each of the first sawtooth units includes a first inclined surface, and each of the second sawtooth units includes a second inclined surface; in any first sawtooth unit and second sawtooth unit that are in contact with each other, the first inclined surface and the second inclined surface are fitted together.

[0020] Optionally, the expansion pad has an axisymmetric structure, and the first direction is perpendicular to the axis of symmetry of the expansion pad; the plurality of first sawtooth units in the first sawtooth structure are symmetrically arranged about the axis of symmetry of the expansion pad, and the plurality of second sawtooth units in the second sawtooth structure are symmetrically arranged about the axis of symmetry of the expansion pad.

[0021] Optionally, the expansion rate of the second sub-pad is greater than that of the first sub-pad, and for any one of the first sawtooth units, the distance between the first inclined surface and the light guide plate gradually increases in the direction of the axis of symmetry toward the expansion pad.

[0022] Alternatively, the expansion rate of the second sub-pad is less than that of the first sub-pad, and for any one of the first sawtooth units, the distance between the first inclined surface and the light guide plate gradually decreases at different positions in the direction of the axis of symmetry toward the expansion pad.

[0023] Optionally, the temperature in the first temperature range is greater than 25°C, and the preset threshold is less than or equal to 0.1 mm.

[0024] Optionally, the backlight module further includes a reflective layer located within the receiving cavity; the reflective layer is fixed to the back plate, and the projection of the reflective layer in the direction perpendicular to the light guide plate completely covers the projection of the light source and the expansion pad in the direction perpendicular to the light guide plate; the side of the expansion pad away from the light guide plate is fixed to the reflective layer.

[0025] This application also provides a display device, including a display panel and the backlight module described above; wherein the display panel is located on the light-emitting side of the backlight module, and the backlight module further includes an optical film group located between the light guide plate and the display panel.

[0026] The backlight module and display device provided in this application, by setting an expansion pad above the light guide plate, allow the expansion pad to expand when it is within a first temperature range, such as during a temperature test (e.g., TST). During expansion, the distance between the expansion pad and the light guide plate gradually decreases, resulting in a distance between the expanded expansion pad and the light guide plate that is greater than or equal to 0 and less than a preset threshold. By setting the preset threshold, the distance between the expanded expansion pad and the light guide plate can be limited to a small range, thereby restricting the wrinkle space of the flexible circuit board and thus limiting the degree of wrinkling, improving the TST lighting problem caused by the wrinkles of the flexible circuit board. When the expansion pad expands to a distance equal to or close to 0 between it and the light guide plate, the wrinkles of the flexible circuit board can be limited to the maximum extent, thereby completely improving the TST lighting problem caused by the wrinkles of the flexible circuit board. Furthermore, when the expansion pad does not expand, it is obvious that the distance between the expansion pad and the light guide plate is greater than the preset threshold, ensuring that the light guide plate and light source structures can be smoothly installed into the receiving cavity of the back plate. Therefore, this application can effectively solve the problem of poor TST light shadow caused by wrinkles in flexible circuit boards while ensuring the assemblability of the light guide plate and the light source. Attached Figure Description

[0027] The technical solution and other beneficial effects of this application will become apparent from the following detailed description of specific embodiments in conjunction with the accompanying drawings.

[0028] Figure 1 This is a schematic diagram of a partial cross-sectional structure of an exemplary side-lit backlight module.

[0029] Figure 2 This is a schematic diagram of a partial cross-sectional structure of a backlight module in a second temperature range, provided as an embodiment of this application.

[0030] Figure 3 This is a schematic diagram of a partial cross-sectional structure of a backlight module within a first temperature range, provided as an embodiment of this application.

[0031] Figure 4 for Figure 2 A magnified view of a portion of the expansion gasket.

[0032] Figure 5 for Figure 4 A magnified view of a portion of the expansion gasket.

[0033] Figure 6 This is a magnified view of another type of expansion pad in its initial state.

[0034] Figure 7 for Figure 6 A magnified view of the expansion pad in an expanded state. Detailed Implementation

[0035] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0036] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "a plurality of" means two or more, unless otherwise explicitly specified.

[0037] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0038] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0039] The following disclosure provides many different embodiments or examples for implementing different structures of this application. To simplify the disclosure, specific examples of components and arrangements are described below. Of course, these are merely examples and are not intended to limit the scope of this application. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, various specific examples of processes and materials are provided in this application, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0040] like Figure 1 As shown, an exemplary side-lit backlight module 1 includes a backplate 2, a flexible printed circuit (FPC) 3, a first reflective layer 4, a light source 5, a light guide plate 6, an optical film assembly 7, a second reflective layer 8, and a light-shielding adhesive 9. The backplate 2 is composed of an integrally formed bottom plate 2a, a support plate 2b, and a top plate 2c; the two opposite ends of the support plate 2b are perpendicularly connected to the bottom plate 2a and the top plate 2c, respectively, to form a U-shaped receiving cavity 10. The flexible circuit board 3 and the first reflective layer 4 are located on the bottom plate 2a of the back plate 2; the light guide plate 6 is located in the U-shaped cavity 10 of the back plate 2 and is located on the first reflective layer 4 and the flexible circuit board 3; the light source 5 is located on the side of the light guide plate 6 near the support plate 2b and is located on the flexible circuit board 3; the optical film assembly 7 is located on the light guide plate 6; the second reflective layer 8 is fixed to the top plate 2c near the light source 5 by adhesive and is disposed corresponding to the light source 5 and part of the light guide plate 6; the light-shielding adhesive 9 covers the side of the top plate 2c away from the second reflective layer 8 and extends to cover part of the optical film assembly 7. The optical film assembly 7 includes a lower diffuser 7a, a lower brightness enhancement film 7b, an upper brightness enhancement film 7c and an upper diffuser 7d stacked sequentially on the light guide plate 6.

[0041] Specifically, the flexible circuit board 3 can be fixedly connected to the light guide plate 6 using adhesive, and the light source 5 is electrically connected to the flexible circuit board 3. For the integrated light guide structure, the light source 5 and the light guide plate 6 can also be fixedly connected using adhesive. In order to ensure that the integrated light guide structure can be assembled into the U-shaped receiving cavity 10 of the back plate 2, a certain gap D0 needs to be reserved between the light guide plate 6 and the second reflective layer 8.

[0042] However, during the TST (thermal shock test) of the backlight module 1, the integrated light guide structure is prone to TST shadow defects, which are usually caused by wrinkles in the flexible circuit board 3 during the TST process. To improve the TST shadow defect problem, a common practice is to minimize the gap D0 between the light guide plate 6 and the second reflective layer 8, thus limiting the degree of wrinkling in the flexible circuit board 3. However, to ensure the assemblability of the light guide plate 6 and the light source 5, the gap between the light guide plate 6 and the second reflective layer 8 cannot be infinitely small. Therefore, it is difficult to completely and thoroughly solve the TST shadow defect problem.

[0043] To address the aforementioned technical problems, this application provides a backlight module and a display device. By placing an expansion pad above a light guide plate, the gap between the expansion pad and the light guide plate is greater than 0 when the expansion pad is not expanded. During temperature testing (e.g., TST), the expansion pad can expand, gradually reducing the gap between the expansion pad and the light guide plate. This limits the degree of wrinkling of the flexible circuit board. When the expansion pad expands to directly contact the light guide plate, it completely limits the wrinkling of the flexible circuit board, thereby thoroughly improving the problem of poor TST lighting caused by wrinkles in the flexible circuit board.

[0044] like Figure 2 As shown, this application embodiment provides a side-lit backlight module 11, which includes at least a backplate 12, a flexible printed circuit board (FPC) 13, a light guide plate 14, a light source 15, and an expansion pad 16. The backplate 12 has a receiving cavity 17; the flexible printed circuit board 13 is at least partially located within the receiving cavity 17 and disposed near the bottom of the receiving cavity 17; the light guide plate 14 is partially located within the receiving cavity 17 and fixed to the flexible printed circuit board 13; the light source 15 is located within the receiving cavity 17 and on the flexible printed circuit board 13; the light source 15 is disposed on the side near the light guide plate 14; and the expansion pad 16 is located within the receiving cavity 17 and on the side of the light guide plate 14 away from the flexible printed circuit board 13.

[0045] Specifically, within the first temperature range, the expansion pad 16 is in an expanded state, and the distance between the expansion pad 16 and the light guide plate 14 is greater than or equal to 0 and less than a preset threshold.

[0046] It is understood that, in the embodiments of this application, the expansion pad 16 can be made by selecting appropriate materials so that the distance between the expanded expansion pad 16 and the light guide plate 14 after expansion is between 0 and a preset threshold.

[0047] In one specific embodiment, the expansion pad 16 expands only within a first temperature range, and when the temperature of the expansion pad 16 is lower than the lowest temperature within the first temperature range, the expansion pad 16 can return to the state before expansion; that is, the expansion state of the expansion pad 16 is reversible.

[0048] For example, during a temperature test (e.g., TST), the temperature of the expansion pad 16 is high (e.g., above room temperature), and the expansion pad 16 will expand. At this time, the distance between the expansion pad 16 and the light guide plate 14 is greater than or equal to 0 and less than a preset threshold. At room temperature, the expansion pad 16 can return to its unexpanded state. At this time, the distance between the expansion pad 16 and the light guide plate 14 is greater than or equal to the preset threshold.

[0049] In another specific embodiment, after the expansion pad 16 expands, even if the temperature of the expansion pad 16 drops below the lowest temperature in the first temperature range, the expansion pad 16 cannot return to its unexpanded state; that is, the expansion state of the expansion pad 16 is irreversible.

[0050] For example, after a temperature test (e.g., TST) is conducted, the temperature drops to room temperature, at which point the expansion pad 16 remains in an expanded state; that is, once the expansion pad 16 expands, the distance between the expansion pad 16 and the light guide plate 14 remains unchanged or remains within a small range.

[0051] It is understood that whether the expansion state of the expansion pad 16 is reversible depends on the selected expandable material, and this application does not limit this; and since the temperature test (e.g., TST) is carried out after the backlight module is assembled, the expansion pad 16 is in an unexpanded state when the backlight module is assembled. At this time, the distance between the expansion pad 16 and the light guide plate 14 is greater than or equal to a preset threshold, so as to facilitate the installation of the light guide plate 14 and other structures.

[0052] Specifically, within the second temperature range, the expansion pad 16 is in its initial state, and the distance between the expansion pad 16 and the light guide plate 14 is greater than a preset threshold; any temperature in the first temperature range is higher than the temperature in the second temperature range.

[0053] Understandably, the initial state of the expansion gasket 16 refers to the state when the expansion gasket 16 has not expanded, while the expansion state of the expansion gasket 16 refers to the state when the expansion gasket 16 expands.

[0054] Specifically, such as Figure 2 As shown, within the second temperature range, the distance D1 between the expansion pad 16 and the light guide plate 14 is greater than a preset threshold; Figure 3As shown, within the first temperature range, the expansion pad 16 can expand, and during the expansion process, the distance between the expansion pad 16 and the light guide plate 14 gradually decreases from D1 to D2, where D2 is greater than or equal to 0 and less than D1.

[0055] Understandably, within the first temperature range, the gap between the expanded expansion pad 16 and the light guide plate 14 after expansion can be equal to or close to 0.

[0056] Specifically, the first temperature range is the temperature range of the backlight module 11 when the TST test is performed, that is, the temperature range when the expansion pad 16 expands; the second temperature range is the temperature range of the backlight module 11 when the TST test is not performed, that is, the temperature range when the expansion pad 16 does not expand.

[0057] In one specific embodiment, the temperature in the first temperature range is greater than 25°C, and the temperature in the second temperature range is less than or equal to 25°C. For example, at room temperature (25°C), the expansion pad 16 is in its initial state, and the distance D1 between the expansion pad 16 and the light guide plate 14 is greater than a preset threshold. During the TST process, the temperature of the backlight module 11 is greater than 25°C. At this time, the expansion pad 16 expands, and the distance D2 between the expanded expansion pad 16 and the light guide plate 14 is greater than or equal to 0 and less than D1.

[0058] In one specific embodiment, when the temperature of the backlight module 11 is less than or equal to 25°, the expansion pad 16 is in its initial state; when the temperature of the backlight module 11 is greater than 25°, the expansion pad 16 begins to expand, causing the gap between the expansion pad 16 and the light guide plate 14 to decrease; when the temperature of the backlight module 11 is greater than a preset temperature (e.g., 40°), the gap between the expansion pad 16 and the light guide plate 14 is equal to or close to 0.

[0059] Specifically, the preset threshold is less than or equal to 0.1 millimeters (mm). For example, the preset threshold can be 0.1mm, 0.08mm, or 0.05mm.

[0060] In one specific embodiment, when the expansion pad 16 is in the initial state, the distance D1 between the expansion pad 16 and the light guide plate 14 is equal to 0.1 mm. When the temperature of the backlight module 11 is greater than the preset temperature (e.g., 40°), the distance D2 between the expansion pad 16 and the light guide plate 14 is equal to 0 or 0.01 mm.

[0061] Understandably, within the second temperature range, the distance D1 between the expansion pad 16 and the light guide plate 14 is greater than a preset threshold, ensuring that the light guide plate 14 can be smoothly installed into the receiving cavity 17 of the back plate 12. Within the first temperature range, the expansion pad 16 expands, causing the distance between the expansion pad 16 and the light guide plate 14 to gradually decrease to D2, where D2 is less than D1. This, to a certain extent, restricts the space for the flexible circuit board 13 to wrinkle due to high temperature, thereby limiting the degree of wrinkling of the flexible circuit board 13. When the distance D2 between the expanded expansion pad 16 and the light guide plate 14 is equal to or close to 0, the expansion pad 16 and the light guide plate 14 are in direct contact, completely restricting the space for the flexible circuit board 13 to wrinkle due to high temperature, thus completely limiting the wrinkling of the flexible circuit board 13 and improving the problem of poor TST lighting.

[0062] It should be noted that within the first temperature range, the light guide plate 14 can also expand to a certain extent. When the expansion pad 16 and the light guide plate 14 expand simultaneously, the distance between them gradually decreases to D2. Of course, whether the light guide plate 14 expands depends on its material properties, and this application does not limit this.

[0063] Specifically, the backplate 12 includes a bottom plate 12a, a top plate 12c disposed opposite to the bottom plate 12a, and a support plate 12b connecting the bottom plate 12a and the top plate 12c, and the bottom plate 12a, the support plate 12b, and the top plate 12c form a receiving cavity 17; the flexible circuit board 13 is located in the receiving cavity 17 and is located on the side of the bottom plate 12a facing the top plate 12c; the light guide plate 14 is located in the receiving cavity 17 and is located on the side of the flexible circuit board 13 facing the top plate 12c; the light source 15 is located on the side of the light guide plate 14 near the support plate 12b and is located on the flexible circuit board 13; the expansion pad 16 is located between the light guide plate 14 and the top plate 12c.

[0064] Understandably, the bottom of the receiving cavity 17 refers to the side of the bottom plate 12a facing the top plate 12c.

[0065] In one specific implementation, such as Figure 2 and Figure 3 As shown, the bottom plate 12a, support plate 12b, and top plate 12c of the back plate 12 are integrally formed, and the receiving cavity 17 formed by the bottom plate 12a, support plate 12b, and top plate 12c is a U-shaped structure. Of course, in other embodiments, the bottom plate 12a, support plate 12b, and top plate 12c of the back plate 12 can also be separate structures.

[0066] Specifically, such as Figure 4 and Figure 5As shown, the expansion pad 16 includes a first sub-pad 16a and a second sub-pad 16b with different expansion rates; the first sub-pad 16a is located between the top plate 12c and the second sub-pad 16b, and the second sub-pad 16b is located between the first sub-pad 16a and the light guide plate 14. The first sub-pad 16a includes a first serrated structure 18 disposed near the second sub-pad 16b, and the second sub-pad 16b includes a second serrated structure 19 disposed near the first sub-pad 16a, and the first serrated structure 18 and the second serrated structure 19 are toothed together. Within a first temperature range, at least one of the first sub-pad 16a and the second sub-pad 16b can expand in the length direction of the expansion pad 16, and during the expansion process, the contact area between the first serrated structure 18 and the second serrated structure 19 gradually decreases.

[0067] It should be noted that the thickness direction of the expansion gasket 16 is perpendicular to the direction of the expansion gasket 16, for example, as shown in the figure. Figure 2 The Y direction and the direction opposite to the Y direction; the length direction of the expansion pad 16 is perpendicular to the thickness direction of the expansion pad 16, for example, as shown in the figure. Figure 2 The X direction and the direction opposite to the X direction.

[0068] Understandably, within the first temperature range, at least one of the first sub-gasket 16a and the second sub-gasket 16b can expand in the X direction and in the opposite direction. For example, the first sub-gasket 16a and / or the second sub-gasket 16b may extend towards the edge of the expanding gasket 16. Since the first serrated structure 18 of the first gasket and the second serrated structure 19 of the second sub-gasket 16b are mutually contacting reverse serrated structures, there is a mutual repulsion between the first serrated structure 18 and the second serrated structure 19 during the expansion and extension process. This causes the first serrated structure 18 and the second serrated structure 19 to undergo reverse displacement, and the contact area between the first serrated structure 18 and the second serrated structure 19 gradually decreases, thereby achieving the effect of effectively increasing the overall thickness of the first sub-gasket 16a and the second sub-gasket 16b.

[0069] In other words, when at least one of the first sawtooth structure 18 and the second sawtooth structure 19 expands, they repel each other in the thickness direction, thereby increasing the overall thickness of the first sub-pad 16a and the second sub-pad 16b, that is, increasing the overall thickness of the expansion pad 16, and finally making the gap between the expansion pad 16 and the light guide plate 14 zero.

[0070] like Figure 4 As shown, within the second temperature range, the expansion gasket 16 does not expand, and at this time, the overall thickness of the expansion gasket 16 is H1; Figure 5As shown, within the first temperature range, after the expansion gasket 16 expands, the overall thickness of the expansion gasket 16 is H2, where H2 is greater than H1. It can be understood that the difference between H2 and H1 is equal to the difference between D1 and D2.

[0071] Understandably, when the expansion pad 16 expands to a large extent, it will even exert a squeezing force on the light guide plate 14 towards the flexible circuit board 13 after it expands to contact the light guide plate 14, thereby effectively preventing the flexible circuit board 13 from wrinkling.

[0072] It should be noted that the expansion pad 16 in this embodiment is a double-layer pad structure. Compared with the single-layer expansion pad 16 structure, the double-layer pad in this embodiment has a better expansion effect due to the reverse serrated structure between them. It is easier to achieve a gap between the expansion pad 16 and the light guide plate 14 that is equal to or close to 0, and even to achieve a squeezing force on the light guide plate 14 towards the flexible circuit board 13 after expansion.

[0073] Understandably, if a single-layer expansion gasket 16 is used, the expansion rate of the material is required to be higher.

[0074] In one specific embodiment, within a first temperature range, both the first sub-gasket 16a and the second sub-gasket 16b can expand in the X direction and in the opposite direction to the X direction, and their expansion rates are different; this design makes the expansion effect of the expansion gasket 16 better.

[0075] Specifically, within the first temperature range, at least one of the first sub-gasket 16a and the second sub-gasket 16b can also expand in the thickness direction of the expansion gasket 16, a design that makes it easier for the expansion gasket 16 to expand to contact the light guide plate 14.

[0076] In one specific embodiment, within a first temperature range, both the first sub-gasket 16a and the second sub-gasket 16b can expand in the thickness direction of the expansion gasket 16, which makes the expansion effect of the expansion gasket 16 better.

[0077] Specifically, such as Figures 2 to 5 As shown, the first serrated structure 18 includes a plurality of first serrated units 20 arranged sequentially along a first direction (e.g., the X direction), and the second serrated structure 19 includes a plurality of second serrated units 21 arranged sequentially along the first direction; the plurality of first serrated units 20 and the plurality of second serrated units 21 are toothed together, and each first serrated unit 20 is in contact with one second serrated unit 21. Each first serrated unit 20 includes a first inclined surface 22, and each second serrated unit 21 includes a second inclined surface 23; in any of the first serrated units 20 and second serrated units 21 that are in contact with each other, the first inclined surface 22 and the second inclined surface 23 are fitted together.

[0078] In the aforementioned embodiments, the cross-sectional shape of the first sawtooth unit 20 includes either a triangle or a trapezoid, and the cross-sectional shape of the second sawtooth unit 21 includes either a triangle or a trapezoid. It is understood that the first sawtooth unit 20 and the second sawtooth unit 21 are opposite sawtooths; the cross-sectional shapes of the first sawtooth unit 20 and the second sawtooth unit 21 can be the same shape in opposite directions, or they can be different shapes in opposite directions, as long as the surfaces in contact with each other are inclined planes.

[0079] In one specific embodiment, the slopes of the first inclined plane 22 and the second inclined plane 23 are the same, but it is not limited thereto.

[0080] Of course, in other embodiments, in the first sawtooth unit 20 and the second sawtooth unit 21, the cross-sectional shape of one of the sawtooth units can be hemispherical, and the cross-sectional shape of the other sawtooth unit can be either triangular or trapezoidal. In this case, the curved surface of the sawtooth unit with a hemispherical cross-section is in contact with the inclined surface of the sawtooth unit with a triangular or trapezoidal cross-section.

[0081] In one specific implementation, such as Figures 2 to 5 As shown, the expansion pad 16 has an axisymmetric structure, and the first direction is perpendicular to the axis of symmetry of the expansion pad 16; the plurality of first sawtooth units 20 in the first sawtooth structure 18 are symmetrically arranged about the axis of symmetry L of the expansion pad 16, and the plurality of second sawtooth units 21 in the second sawtooth structure 19 are symmetrically arranged about the axis of symmetry L of the expansion pad 16.

[0082] Understandably, the first sawtooth structure 18 is an axisymmetric structure. For example, the multiple first sawtooth units 20 in the first sawtooth structure 18 can be divided into two groups of first sawtooth units 20 symmetrically arranged about the axis of symmetry L, and the inclination direction of the first inclined surface 22 of the two groups of first sawtooth units 20 is also symmetrically arranged about the axis of symmetry L. Similarly, the second sawtooth structure 19 is also an axisymmetric structure. For example, the multiple second sawtooth units 21 in the second sawtooth structure 19 can be divided into two groups of second sawtooth units 21 symmetrically arranged about the axis of symmetry L, and the inclination direction of the second inclined surface 23 of the two groups of second sawtooth units 21 is also symmetrically arranged about the axis of symmetry L.

[0083] Specifically, in the two sets of first sawtooth units 20 arranged symmetrically, the two first sawtooth units 20 located on both sides of the axis of symmetry L and arranged adjacently can be connected to each other and integrally formed; and in the two sets of second sawtooth units 21 arranged symmetrically, the two second sawtooth units 21 located on both sides of the axis of symmetry L and arranged adjacently can be connected to each other and integrally formed.

[0084] In one specific embodiment, the expansion rate of the second sub-gasket 16b is greater than that of the first sub-gasket 16a; for example, the first sub-gasket 16a is made of metal, while the second sub-gasket 16b is made of rubber, and the difference in their expansion rates is significant, which is beneficial for achieving mutual repulsion between the first serrated structure 18 and the second serrated structure 19 during the expansion process. At this time, as... Figure 3 As shown, for any first sawtooth unit 20, the distance between the first inclined surface 22 of the first sawtooth unit 20 and the light guide plate gradually increases in the direction of the axis of symmetry L towards the expansion pad 16.

[0085] At the same time, such as Figure 3 As shown, for any second sawtooth unit 21, the distance between the second inclined surface 23 of the second sawtooth unit 21 and the light guide plate gradually increases in the direction of the axis of symmetry L towards the expansion pad 16.

[0086] Specifically, the two first sawtooth units 20 located on both sides of the axis of symmetry L are connected to each other and integrally formed to form a groove structure; the two second sawtooth units 21 located on both sides of the axis of symmetry L are connected to each other and integrally formed to form a protrusion structure corresponding to the groove structure.

[0087] In another specific embodiment, the expansion rate of the second sub-gasket 16b is less than that of the first sub-gasket 16a; for example, the first sub-gasket 16a is made of rubber, while the second sub-gasket 16b is made of metal. In this case, as... Figure 6 and Figure 7 As shown, for any first sawtooth unit 20, the distance between the first inclined surface 22 of the first sawtooth unit 20 and the light guide plate gradually decreases in the direction of the axis of symmetry L toward the expansion pad 16.

[0088] At the same time, such as Figure 6 and Figure 7 As shown, for any second sawtooth unit 21, the distance between the second inclined surface 23 of the second sawtooth unit 21 and the light guide plate gradually decreases at different positions in the direction of the axis of symmetry L toward the expansion pad 16.

[0089] Specifically, the two first sawtooth units 20 located on both sides of the axis of symmetry L are connected to each other and integrally formed to form a protruding structure; the two second sawtooth units 21 located on both sides of the axis of symmetry L are connected to each other and integrally formed to form a groove structure corresponding to the protruding structure.

[0090] It should be noted that the slopes of the first inclined surfaces 22 of the multiple first sawtooth units 20 located on the same side of the axis of symmetry L can be the same or different; and the first sawtooth units 20 can be arranged at equal intervals or at non-equal intervals. That is to say, this application does not limit the slopes of the first inclined surfaces 22 of different first sawtooth units 20, and does not limit the spacing between two adjacent first sawtooth units 20, as long as the first sub-shield 16a and the second sub-shield 16b can be mutually exclusive during the expansion process.

[0091] Similarly, this application does not limit the slope of the second inclined surface 23 of different second sawtooth units 21, nor does it limit the spacing between two adjacent second sawtooth units 21. As long as the second sawtooth unit 21 is correspondingly arranged with the first sawtooth unit 20 and the first inclined surface 22 and the second inclined surface 23 are in contact, the first sawtooth structure 18 and the second sawtooth structure 19 can be toothed together.

[0092] Of course, in other embodiments, the expansion pad 16 may not be an axisymmetric structure. For example, the inclination direction and slope of the first inclined surface 22 of the plurality of first sawtooth units 20 in the first sawtooth structure 18 are consistent, and the inclination direction and slope of the second inclined surface 23 of the plurality of second sawtooth units 21 in the second sawtooth structure 19 are consistent.

[0093] Specifically, the contact points of the first sub-gasket 16a and the second sub-gasket 16b are fixedly connected by an adhesive, for example, the first sawtooth unit 20 and the corresponding second sawtooth unit 21 are fixedly connected by dispensing adhesive. Within a first temperature range, the adhesive has extensibility, so it will not affect the extensibility between the first sawtooth unit 20 and the second sawtooth unit 21.

[0094] Specifically, such as Figure 2 and Figure 3 As shown, the backlight module 11 also includes a reflective layer 24 located within the receiving cavity 17, used to reflect light from the light source 15 directed towards the top plate 12c into the light guide plate 14. The reflective layer 24 is fixed to the back plate 12, specifically located between the top plate 12c and the expansion pad 16; the side of the expansion pad 16 away from the light guide plate 14 is fixed to the reflective layer 24. Furthermore, the projection of the reflective layer 24 in the direction perpendicular to the light guide plate 14 completely covers the projections of the light source 15 and the expansion pad 16 in the direction perpendicular to the light guide plate 14.

[0095] Specifically, the reflective layer 24 can be fixed to the top plate 12c with adhesive, and the expansion pad 16 can also be fixed to the reflective layer 24 with adhesive.

[0096] Specifically, light source 15 includes, but is not limited to, LED light sources.

[0097] Specifically, such as Figure 2 and Figure 3 As shown, the backlight module 11 also includes a reflective sheet 25 located between the floor and the light guide plate 14.

[0098] Specifically, such as Figure 2 and Figure 3 As shown, the backlight module 11 also includes an optical film group 26 located on the light guide plate 14. The optical film group 26 includes a lower diffuser 26a, a lower brightness enhancement film 26b, an upper brightness enhancement film 26c and an upper diffuser 26d stacked sequentially on the light guide plate 14.

[0099] In one specific implementation, such as Figure 2 and Figure 3 As shown, the backlight module 11 also includes a light-shielding adhesive 27 located on the side of the top plate 12c away from the reflective layer 24, which extends to cover a portion of the optical film assembly 26.

[0100] In this embodiment, a double-layer expansion pad 16 is provided between the reflective layer 24 and the light guide plate 14. When the expansion pad 16 is in its initial state (unexpanded state), the expansion pad 16 does not expand, and the distance between the unexpanded expansion pad 16 and the light guide plate 14 is greater than a preset threshold. This ensures that during the assembly of the backlight module 11, the light guide plate 14 and the light source 15 can be smoothly assembled into the receiving cavity 17 of the backplate 12. When the expansion pad 16 is within a first temperature range, for example during the TST test... The expansion pad 16 can expand under high temperature, and the gap between the expanded expansion pad 16 and the light guide plate 14 will decrease after expansion, thereby limiting the wrinkle space of the flexible circuit board and thus limiting the degree of wrinkling of the flexible circuit board 13. When the expansion pad 16 expands to the point where the gap between it and the light guide plate 14 is equal to or close to 0, the expansion pad 16 is equivalent to completely filling the space between the reflective layer 24 and the light guide plate 14. At this time, the wrinkles of the flexible circuit board 13 can be limited to the maximum extent, thereby completely improving the problem of poor TST lighting. Therefore, this application can effectively improve the problem of poor TST lighting caused by wrinkles in the flexible circuit board 13 while ensuring that the light guide plate 14 and the light source 15 can be assembled.

[0101] This application also provides a display device, which includes a display panel and the backlight module described in the foregoing embodiments; wherein the display panel is located on the light-emitting side of the backlight module. Specifically, the display panel is located on the side of the optical film group away from the light guide plate.

[0102] Specifically, the display panel is an LCD display panel.

[0103] In this embodiment, the problem of poor TST backlighting in the backlight module has been thoroughly improved, thereby effectively enhancing the display quality of the display device.

[0104] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0105] The foregoing has provided a detailed description of a backlight module and display device provided in the embodiments of this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the technical solutions and core ideas of this application. Those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A backlight module, characterized in that, include: Back plate, with receiving cavity; A flexible circuit board is located at least partially within the receiving cavity and is disposed near the bottom of the receiving cavity; The light guide plate is partially located within the receiving cavity and fixed to the flexible circuit board; A light source is located within the receiving cavity and on the flexible circuit board; the light source is positioned on the side near the light guide plate. An expansion pad is located within the receiving cavity and on the side of the light guide plate away from the flexible circuit board; Within a first temperature range, the expansion pad expands at least in the thickness direction of the expansion pad, the distance between the expansion pad and the light guide plate is greater than or equal to 0 and less than a preset threshold, the temperature in the first temperature range is greater than 25°C, and the preset threshold is less than or equal to 0.1 mm; within a second temperature range, the distance between the expansion pad and the light guide plate is greater than or equal to the preset threshold, and the temperature in the second temperature range is less than or equal to 25°C.

2. The backlight module according to claim 1, characterized in that, The expansion pad includes a first sub-pad and a second sub-pad with different expansion rates; the first sub-pad is located on the side of the second sub-pad away from the light guide plate, and the second sub-pad is located between the first sub-pad and the light guide plate; The first sub-wafer includes a first serrated structure disposed near the second sub-wafer, and the second sub-wafer includes a second serrated structure disposed near the first sub-wafer, wherein the first serrated structure and the second serrated structure are toothed together. Within the first temperature range, at least one of the first sub-gasket and the second sub-gasket can expand in the length direction of the expansion gasket, and during the expansion process, the contact area between the first serrated structure and the second serrated structure gradually decreases.

3. The backlight module according to claim 2, characterized in that, Within the first temperature range, at least one of the first sub-gasket and the second sub-gasket may also expand in the thickness direction of the expansion gasket.

4. The backlight module according to claim 2, characterized in that, The first sawtooth structure includes a plurality of first sawtooth units arranged sequentially along a first direction, and the second sawtooth structure includes a plurality of second sawtooth units arranged sequentially along the first direction; the plurality of first sawtooth units and the plurality of second sawtooth units are toothed to each other, and each first sawtooth unit is in contact with a corresponding second sawtooth unit. Each of the first sawtooth units includes a first inclined surface, and each of the second sawtooth units includes a second inclined surface; in any first sawtooth unit and second sawtooth unit that are in contact with each other, the first inclined surface and the second inclined surface are fitted together.

5. The backlight module according to claim 4, characterized in that, The expansion pad has an axisymmetric structure, and the first direction is perpendicular to the axis of symmetry of the expansion pad; the plurality of first sawtooth units in the first sawtooth structure are symmetrically arranged about the axis of symmetry of the expansion pad, and the plurality of second sawtooth units in the second sawtooth structure are symmetrically arranged about the axis of symmetry of the expansion pad.

6. The backlight module according to claim 5, characterized in that, The expansion rate of the second sub-pad is greater than that of the first sub-pad, and for any one of the first sawtooth units, the distance between the first inclined surface and the light guide plate gradually increases in the direction of the axis of symmetry toward the expansion pad. Alternatively, the expansion rate of the second sub-pad is less than that of the first sub-pad, and for any one of the first sawtooth units, the distance between the first inclined surface and the light guide plate gradually decreases at different positions in the direction of the axis of symmetry toward the expansion pad.

7. The backlight module according to claim 1, characterized in that, The backlight module further includes a reflective layer located within the receiving cavity; the reflective layer is fixed to the side of the back plate near the light guide plate, and the projection of the reflective layer in the direction perpendicular to the light guide plate completely covers the projection of the light source and the expansion pad in the direction perpendicular to the light guide plate; the side of the expansion pad away from the light guide plate is fixed to the reflective layer.

8. A display device, characterized in that, The device includes a display panel and a backlight module as described in any one of claims 1 to 7; wherein the display panel is located on the light-emitting side of the backlight module, and the backlight module further includes an optical film assembly located between the light guide plate and the display panel.

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