Backlight module and display device

Abstract

The application discloses a backlight module and a display device. The backlight module comprises a back plate, a plurality of side plates and a bottom plate of the back plate, wherein the plurality of side plates and the bottom plate form an accommodating space, the plurality of side plates comprise at least one first side plate and a plurality of second side plates, a light guide plate is located in the accommodating space and comprises a light entrance surface and a plurality of non-light entrance surfaces, the light entrance surface is opposite to the first side plate, the plurality of non-light entrance surfaces are arranged opposite to the plurality of second side plates one by one, at least one lamp strip is fixed on the inner wall of the at least one first side plate one by one, each lamp strip has a first assembly gap with the corresponding light entrance surface, a plurality of first reflecting sheets are attached to the plurality of non-light entrance surfaces one by one, and a plurality of positioning optical film sheets are attached to the inner walls of the plurality of second side plates, wherein the positioning optical film sheets have a second assembly gap with the first reflecting sheets. The backlight module can meet the requirements of a narrow frame of a display screen and the high display grade of customers.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of display devices, in particular to a backlight module and a display device. BACKGROUND

[0002] In addition to the applications of instruments, central controls, rearview mirrors and the like, more and more customers choose to use small-size display screens in products such as air conditioners, one-key starting, face recognition and seat control, and the vehicle-mounted display is developing towards multi-screen, full-signal and narrow frame in the vehicle.

[0003] At present, in the backlight module of a conventional small-size vehicle-mounted display screen, a light guide plate is arranged in a back plate, and a rubber pad is usually used for positioning between the light guide plate and the side plate of the back plate, and the rubber pad is usually arranged at the corner position of the light guide plate for positioning. In order to realize the narrow frame feature of the conventional small-size vehicle-mounted display screen, three methods are usually adopted, the first method is to thin the rubber pad, the second method is to clamp the rubber pad on the side wall of the back plate, and the third method is to reduce the distance from the edge of the optical film to the effective light-emitting area of the backlight module. However, after the narrow frame is realized by the above-mentioned methods, the problems of light leakage at the corner of the vehicle-mounted display screen with a large viewing angle, poor shadow, poor brightness uniformity and poor display quality may still occur, and therefore it is a technical difficulty to meet the requirements of high display taste of customers while realizing the narrow frame requirement of the small-size display screen. SUMMARY

[0004] The present application provides a backlight module and a display device, which can meet the requirements of narrow frame of the display screen and high display taste of customers.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0006] A backlight module comprises:

[0007] A back plate comprising a bottom plate and a plurality of side plates connected to the edges of the bottom plate, the plurality of side plates and the bottom plate enclosing a containing space, the plurality of side plates comprising at least one first side plate and a plurality of second side plates;

[0008] A light guide plate located in the containing space and comprising an incident light surface and a plurality of non-incident light surfaces, the incident light surface being opposite to the first side plate, and the plurality of non-incident light surfaces being arranged opposite to the plurality of second side plates one by one;

[0009] At least one light bar fixed on the inner wall of the at least one first side plate one by one, each light bar having a first assembly gap between the corresponding incident light surface;

[0010] A plurality of first reflective sheets attached to the plurality of non-incident light surfaces one by one;

[0011] a plurality of positioning optical films attached to the inner walls of the plurality of second side plates, the positioning optical films having a second assembly gap with the first reflective sheet.

[0012] Optionally, the adjacent ends of two adjacent second side plates cooperatively form a limiting corner, and the plurality of second side plates cooperatively form a plurality of limiting corners.

[0013] The plurality of positioning optical films can be divided into a plurality of film groups, and the plurality of film groups are attached to the plurality of limiting corners one by one, each of the film groups comprising two positioning optical films, and the two positioning optical films being attached to the adjacent two ends of two adjacent second side plates, respectively.

[0014] Optionally, the edges formed by the intersection of the two non-light-incident surfaces have a light-transmitting region with the adjacent first reflective sheet, and the light-transmitting region is opposite to the positioning optical film.

[0015] Optionally, in each of the film groups, the two positioning optical films have a third assembly gap.

[0016] Optionally, the ends of two adjacent second side plates have a gap, and the end of one positioning optical film in the film group abuts against the inner wall of the second side plate to cooperatively close the gap.

[0017] Optionally, the distance between the surface of the positioning optical film away from the bottom plate and the surface of the light guide plate adjacent to the bottom plate is a first distance, the distance between the surface of the light guide plate away from the bottom plate and the surface of the light guide plate adjacent to the bottom plate is a second distance, and the first distance is less than the second distance.

[0018] Optionally, the surface of the positioning optical film adjacent to the bottom plate abuts against the bottom plate.

[0019] Optionally, the positioning optical film is a second reflective sheet.

[0020] Optionally, the second reflective sheet is a self-adhesive reflective sheet, the second reflective sheet comprising double-sided adhesive tape and a reflective sheet attached to one side of the double-sided adhesive tape, the double-sided adhesive tape comprising a flexible base material and pressure-sensitive adhesive on both sides of the flexible base material, and the reflective sheet comprising a foaming layer and a protective layer on both sides of the foaming layer.

[0021] Optionally, the positioning optical film is a light-shielding sheet.

[0022] Optionally, the back plate is formed by stamping sheet metal.

[0023] Optionally, a bottom reflective sheet is further included between the light guide plate and the bottom plate, and an optical film is further included on a side of the light guide plate away from the bottom plate.

[0024] Optionally, a middle frame is further included, and the middle frame includes a connecting frame and a bearing frame.

[0025] The connecting frame is located outside the plurality of side plates of the back plate and is clamped with the plurality of side plates, and a fourth assembly gap is formed between the connecting frame and the side plates.

[0026] The bearing frame is located on a side of the optical film away from the light guide plate, a fourth assembly gap is formed between the bearing frame and the optical film, and the bearing frame has a window opposite the optical film for light transmission.

[0027] Optionally, the middle frame is a middle rubber frame or a middle iron frame.

[0028] The application further provides a display device including any one of the backlight modules provided in the technical solutions.

[0029] The backlight module provided by the application includes a back plate, a light guide plate, at least one light bar, a plurality of first reflective sheets and a plurality of positioning optical films. The plurality of side plates of the back plate and the bottom plate enclose a containing space, the plurality of side plates include at least one first side plate and a plurality of second side plates, the light guide plate is located in the containing space, the light entrance surface of the light guide plate is opposite the first side plate, and the non-light entrance surface is opposite the plurality of second side plates. The light bar is fixed to the inner wall of the first side plate, and the light bar and the first side wall have a first assembly gap. The plurality of first reflective sheets are attached to the plurality of non-light entrance surfaces, and the plurality of positioning optical films are attached to the inner walls of the plurality of second side plates. The positioning optical film and the first reflective sheet have a second assembly gap. Compared with the related art, the light guide plate can be positioned by the plurality of positioning optical films in the backlight module, and the setting of the rubber pad is cancelled. The thickness of the positioning optical film is thinner than that of the rubber pad, the space occupied is small, the frame of the display screen can be made narrower, and the positioning optical film and the second reflective sheet can not interfere with each other because the positioning optical film and the first reflective sheet have an assembly gap. The first reflective sheet can directly extend to the edge of the corner of the light guide plate, align with the corner of the light guide plate, attach to the non-light entrance surface of the light guide plate, seal the gap between the original rubber pad and the side reflective sheet, and make the distance between the first reflective sheet and the effective light-emitting area of the backlight module large enough. The corner of the light guide plate can provide uniform reflected light, the display brightness uniformity can be improved, the light leakage and dark shadow at the large viewing angle corner can be effectively prevented, the demand for narrow frame of the display screen can be met, and the high display quality of the customer can be met. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 FIG. 1 is a cross-sectional view of a backlight module according to the related art;

[0031] Figure 2 FIG. 2 is a structural schematic view of a backlight module according to the related art;

[0032] Figure 3 FIG. 3 is a cross-sectional view of another backlight module according to the related art;

[0033] Figure 4 FIG. 4 is a cross-sectional view of another backlight module according to the related art;

[0034] Figure 5 FIG. 5 is a structural schematic view of a back plate according to an embodiment of the present application;

[0035] Figure 6 FIG. 6 is a cross-sectional view of a backlight module according to an embodiment of the present application;

[0036] Figure 7 FIG. 7 is a partial structural schematic view of a back plate according to an embodiment of the present application;

[0037] Figure 8 FIG. 8 is a cross-sectional view of a backlight module according to an embodiment of the present application;

[0038] Figure 9 FIG. 9 is a partial structural schematic view of a backlight module according to an embodiment of the present application;

[0039] Figure 10 FIG. 10 is a partial structural schematic view of a back plate according to an embodiment of the present application;

[0040] Figure 11 FIG. 11 is a structural schematic view of a second reflective sheet according to an embodiment of the present application;

[0041] Figure 12 FIG. 12 is a structural schematic view of an assembled component according to an embodiment of the present application;

[0042] Figure 13 FIG. 13 is a structural schematic view of an assembled component according to an embodiment of the present application;

[0043] Figure 14 FIG. 14 is a structural schematic view of a backlight module according to an embodiment of the present application;

[0044] Figure 15 FIG. 15 is a plan structural schematic view of a backlight module according to an embodiment of the present application;

[0045] Figure 16 FIG. 16 is a cross-sectional view of a backlight module according to an embodiment of the present application;

[0046] Figure 17A partial structure schematic diagram of a backlight module provided by an embodiment of the present application.

[0047] Icon:

[0048] 1-back plate; 11-bottom plate; 12-side plate; 121-first side plate; 122-second side plate; 13-gap; 2-light guide plate; 3-lamp strip; 4-first reflective sheet; 5-positioning optical film sheet; 51-second reflective sheet; 511-double-sided adhesive tape; 5111-flexible base material; 5112-pressure sensitive adhesive; 512-reflective sheet; 5121-foaming layer; 5122-protection layer; 6-bottom reflective sheet; 7-optical film material; 8-middle frame; 81-connecting frame; 82-bearing frame; 83-windowing. DETAILED DESCRIPTION

[0049] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0050] In the related art, a partial structure schematic diagram of a backlight module of a small-size display screen can be as shown in Figures 1-4 The display module can include a back plate 01, a light guide plate 02, a lamp strip, a bottom reflective sheet 03, a side reflective sheet 04, an optical film material 05, and a middle frame 06. The light guide plate 02 is located in a containing space of the back plate 01. The lamp strip is located between a light-incident surface of the light guide plate 02 and a side plate of the back plate 01. The bottom reflective sheet 03 is located between the light guide plate 02 and a bottom plate of the back plate 01. The side reflective sheet 04 is attached to a non-light-incident surface of the light guide plate 02. An assembly gap needs to be provided between the non-light-incident surface of the light guide plate 02 and the side plate of the back plate 01. The rubber pad 07 can be provided between the non-light-incident surface of the light guide plate 02 and the side plate of the back plate 01 to limit the light guide plate 02. The optical film material 05 is arranged on a side of the light guide plate 02 away from the bottom plate. The middle frame 06 is connected to an outer side of the side plate of the back plate 01. An assembly gap is provided between the middle frame 06 and the back plate 01. A windowing 061 opposite to the optical film material is provided on a side of the middle frame 06 away from the optical film material. Figure 2 As shown in

[0051] As shown in Figure 1 and 2As shown, the backlight module can have an effective light-emitting area AA and a frame area BB surrounding the effective light-emitting area, and the frame area BB can correspond to the area where the display screen frame is arranged. Rubber pads 07 are arranged at the corners of the light guide plate 02, and the corner light will be insufficient, resulting in low corner brightness of the effective light-emitting area AA, dark shadow defects, poor image uniformity, and inability to meet high uniformity display requirements.

[0052] At the same time, due to the assembly process requirements, a gap of more than 0.3 mm needs to be left between the side reflective sheet 04 and the rubber pad 07. In actual application, when the rubber pad 07 is used to limit the light guide plate 02, as shown in Figure 3 and Figure 4 , the length J of the rubber pad on one side between the light guide plate and the side plate is at least 3 mm, and the distance A of the effective light-emitting area of the backlight module from the edge of the light guide plate is at least 1.8 mm, the distance R of the assembly gap between the side reflective sheet and the rubber pad to the effective light-emitting area = J-A = Min 3-Min 1.8≈1.2 mm, and the assembly gap between the rubber pad and the side reflective sheet has entered the effective light-emitting area in parallel, the assembly gap is not blocked by the reflective sheet, and the light will overflow from the assembly gap, which will inevitably cause the light to leak at the oblique viewing angle.

[0053] Please refer to Figure 5 and Figure 6 , the present application provides a backlight module, comprising:

[0054] a back plate 1, the back plate 1 comprises a bottom plate 11 and a plurality of side plates 12 connected to the edges of the bottom plate 11, the plurality of side plates 12 and the bottom plate 11 form a containing space, and the plurality of side plates 12 comprise at least one first side plate 121 and a plurality of second side plates 122;

[0055] a light guide plate 2, the light guide plate 2 is located in the containing space and comprises a light-incident surface and a plurality of non-light-incident surfaces, the light-incident surface is opposite to the first side plate 121, and the plurality of non-light-incident surfaces are arranged opposite to the plurality of second side plates 122 one by one;

[0056] at least one light bar 3, the at least one light bar 3 is fixed on the inner wall of the at least one first side plate 121 one by one, and each light bar 3 has a first assembly gap with the corresponding light-incident surface;

[0057] a plurality of first reflective sheets 4, the plurality of first reflective sheets 4 are attached to the plurality of non-light-incident surfaces one by one;

[0058] a plurality of positioning optical film pieces 5, the plurality of positioning optical film pieces 5 are attached to the inner walls of the plurality of second side plates 122, and the positioning optical film pieces 5 have a second assembly gap with the first reflective sheets 4.

[0059] The backlight module provided by the embodiment of the present application comprises a back plate 1, a light guide plate 2, at least one lamp strip 3, a plurality of first reflecting sheets 4 and a plurality of positioning optical film sheets 5, wherein the plurality of side plates 12 of the back plate 1 and the bottom plate 11 enclose a containing space, the plurality of side plates 12 comprise at least one first side plate 121 and a plurality of second side plates 122, the light guide plate 2 is located in the containing space, the light-incident surface of the light guide plate 2 is opposite to the first side plate 121, and the non-light-incident surface is opposite to the plurality of second side plates 122 one by one, the lamp strip 3 is fixed on the inner wall of the first side plate 121 one by one, the lamp strip 3 and the first side wall have a first assembly gap, the plurality of first reflecting sheets 4 are attached to the plurality of non-light-incident surfaces one by one, and the plurality of positioning optical film sheets 5 are attached to the inner walls of the plurality of second side plates. Compared with the related art, the light guide plate 2 can be positioned by the plurality of positioning optical film materials 7 in the backlight module, and the setting of the rubber pad is cancelled, the thickness of the positioning optical film material 7 is thinner than that of the rubber pad, the occupied space is small, the frame of the display screen can be made narrower, and since the assembly gap exists between the positioning optical film sheet 5 and the first reflecting sheet 4, the positioning optical film sheet 5 and the second reflecting sheet 51 can not interfere with each other, the first reflecting sheet 4 can directly extend to the edge of the corner of the light guide plate 2, align with the attachment of the corner of the light guide plate 2, attach to the non-light-incident surface of the light guide plate 2, seal the gap between the original rubber pad and the side reflecting sheet, the distance between the first reflecting sheet 4 and the effective light-emitting area of the backlight module is large enough, uniform reflected light can be provided for the corner of the light guide plate 2, the display brightness uniformity is improved, the light leakage and the shadow defect at the large viewing angle corner can be effectively prevented, the display quality is improved, and the requirements of customers for high display quality are met.

[0060] Specifically, the backlight module can be applied to a small-size display screen. For the backlight module of the small-size display screen, the back plate 1 can be formed by punching and stamping sheet metal.

[0061] Specifically, the positioning optical film sheet 5 can be a second reflecting sheet 51 or a light shielding sheet, which is not limited here and is determined according to the actual situation. The positioning optical film sheet 5 can be attached to the second side plate by double-sided adhesive tape.

[0062] Specifically, as shown in the accompanying drawings, Figure 5 The backlight module further comprises a bottom reflecting sheet 6 and an optical film material 7. The bottom reflecting sheet 6 is located between the light guide plate 2 and the bottom plate 11, can ensure the utilization rate of light, and improve the display brightness. The optical film material 7 can be located on the side of the light guide plate 2 away from the bottom plate 11, can optimize the path of the light-emitting light of the backlight module.

[0063] Specifically, as shown in the accompanying drawings, Figure 5As shown, the backlight module can further include a middle frame 8, which includes a connecting frame 81 and a bearing frame 82; the connecting frame 81 is located outside the plurality of side plates 12 of the back plate 1 and is clamped with the plurality of side plates 12, and the connecting frame 81 and the side plates 12 have a fourth assembly gap therebetween; the bearing frame 82 is located on the side of the optical film material 7 away from the light guide plate 2, and the bearing frame 82 and the optical film material 7 have a fourth assembly gap therebetween; and the bearing frame 82 has a window 83 opposite to the optical film material 7 and used for light transmission. The normal projection of the effective light emitting area of the backlight module on the bottom plate 11 is located within the normal projection of the window 83 on the bottom plate 11.

[0064] Specifically, the middle frame 8 can be a middle plastic frame or a middle iron frame, which is not limited here and is determined according to actual conditions.

[0065] In the embodiment of the present application, as shown in Figure 7 As shown, the adjacent end portions between the two adjacent second side plates 122 cooperatively form a limiting corner portion, and the plurality of second side plates 122 cooperatively form a plurality of limiting corner portions; the plurality of positioning optical film pieces 5 can be divided into a plurality of film piece groups, and the plurality of film piece groups can be attached to the plurality of limiting corner portions one by one; each film piece group includes two positioning optical film pieces 5, and the two positioning optical film pieces 5 are respectively attached to the adjacent two end portions of the two adjacent second side plates 122. The positioning optical film pieces 5 are arranged corresponding to the corners of the light guide plate 2, which can more effectively position the light guide plate 2 in the small-size backlight module.

[0066] The gap between the positioning optical film piece 5 and the first reflective sheet 4 can be about 0.2 mm, which can ensure that the first reflective sheet 4 does not touch the two positioning optical film pieces 5 in the expanded state during high-temperature testing.

[0067] In the embodiment of the present application, considering the assembly process error when the first reflective sheet 4 is attached and avoiding interference caused by high-temperature expansion between two adjacent first reflective sheets 4, a predetermined gap can be reserved between the edge of the first reflective sheet 4 and the edge of the corner of the light guide plate 2, that is, the edge formed by the intersection of the two non-light-incident surfaces has a light transmission region CC, as shown in Figure 8 As shown, the light transmission region CC is opposite to the positioning optical film piece 5, as shown in Figure 9 which avoids corner light leakage. The light in the light guide plate 2 can be refracted from the light transmission region, and when the positioning optical film piece 5 is a second reflective sheet 51, the light emitted from the light transmission region can be reflected back into the light guide plate 2. The second reflective sheet 51 attached to the corner of the backlight module can supplement the light of the corner of the light guide plate 2, improve the brightness uniformity of the display screen, and effectively prevent large-view-angle corner light leakage and shadow defects.

[0068] In the embodiment of the present application, as shown in Figure 10As shown, the two positioning optical films 5 have a third assembly gap therebetween, which can avoid interference of the two positioning optical films 5 due to high-temperature expansion. Specifically, the third assembly gap can be about 0.2 mm, which can avoid interference of the two positioning optical films 5 due to thermal expansion and avoid film wrinkles.

[0069] In the embodiment of the present application, the plurality of side plates 12 of the stamping back plate 1 are bent, and the end portions of the two adjacent second side plates 122 have a gap 13, as shown in the figure, that is, the positioning corner portion of the back plate 1 has a gap 13, and the light guide plate 2 has light leaking from the gap 13 of the back plate 1, and external stray light also enters the inside of the backlight module. At this time, the end portion of one of the positioning optical films 5 in the film group corresponding to the positioning corner portion abuts against the inner wall of the second side plate 122 to close the gap 13, which can prevent light from leaking from the gap 13 of the positioning corner portion of the back plate 1 and entering the inside of the backlight module, and improve the light utilization effect of the corner portion of the backlight module and the display effect. Figure 10

[0070] In the embodiment of the present application, as shown in the figure, the distance between the surface of the positioning optical film 5 away from the bottom plate 11 and the surface of the light guide plate 2 adjacent to the bottom plate 11 is a first distance, and the distance between the surface of the light guide plate 2 away from the bottom plate 11 and the surface of the light guide plate 2 adjacent to the bottom plate 11 is a second distance, wherein the first distance can be less than the second distance, which can ensure that the optical film material 7 does not touch the positioning optical film 5 after expansion in the reliability test, and avoid wrinkles of the optical film material 7. Figure 8 Specifically, as shown in the figure, the surface of the positioning optical film 5 adjacent to the bottom plate 11 abuts against the bottom plate 11. In the process of assembling the backlight module, the bottom surface of the positioning optical film 5 abuts against the bottom plate 11, which facilitates the positioning and assembly of the positioning optical film 5, is easy to operate, and avoids the inclination of the positioning optical film 5.

[0071] Figure 8

[0072] ​​​The surface of the bottom plate 11 can be a plane facing the light guide plate 2, and the distance between the surface of the positioning optical film 5 away from the bottom plate 11 and the bottom plate 11 can be less than the distance between the surface of the light guide plate 2 away from the bottom plate 11 and the bottom plate 11. Since the positioning optical film 5 is in contact with the bottom plate 11, the distance between the surface of the positioning optical film 5 away from the bottom plate 11 and the bottom plate 11 is the height h of the positioning optical film 5, and the height h of the positioning optical film 5 is more stringent than the tolerance of a conventional reflective sheet, and the height tolerance needs to be controlled at ±0.08 mm. The distance k between the positioning optical film 5 and the surface of the light guide plate 2 away from the bottom plate 11 can be 0.2 mm, k = the thickness of the light guide plate 2 + the thickness of the bottom reflective sheet 6 - the height h of the positioning optical film 5, and the tolerance of k = (±0.05) + (±0.02) + (±0.08) = ±0.15 mm, so k can be equal to 0.2 ± 0.15 mm, that is, the positioning optical film 5 can be arranged to be 0.2 ± 0.15 mm lower than the surface of the light guide plate 2 away from the bottom plate 11.

[0073] In the embodiment of the present application, as shown in Figure 11 The second reflective sheet 51 can be a self-adhesive reflective sheet, which can include double-sided adhesive 511 and reflective sheet 512 attached to one side of the double-sided adhesive 511. The double-sided adhesive 511 includes flexible substrate 5111 and pressure-sensitive adhesive 5112 on both sides of the flexible substrate. The reflective sheet 512 includes foaming layer 5121 and protective layer 5122 on both sides of the foaming layer. The foaming layer 5121 has micropores to enhance reflection. The self-adhesive reflective sheet can facilitate the assembly of the backlight module. The material of the flexible substrate can be elastic resin, and the material of the foaming layer can be resin. Specifically, the thickness of the second reflective sheet 51 can be determined according to the size of the display screen, which is not limited here, and the thickness of the frame attached to each side plate 12 can be different.

[0074] Specifically, the first reflective sheet 4 can also be a self-adhesive reflective sheet, which is not limited here and is determined according to the actual situation.

[0075] In the actual assembly of the backlight module, the light bar 3 and the positioning optical film 5 can be assembled to the back plate 1 to form a first component, as shown in Figure 5 Then, the light guide plate 2, the bottom reflective sheet 6 and the first reflective sheet 4 are assembled to form a second component, as shown in Figure 12 Then, the second component is assembled into the first component, and the optical film 7 is assembled to the side of the light guide plate 2 away from the bottom plate 11, as shown in Figure 13 Finally, the middle frame 8 is assembled, and the backlight module is formed, as shown in Figure 14

[0076] The present application also provides a display device comprising any one of the backlight modules provided in the technical solutions.​

[0077] The display device can be a small-sized vehicle-mounted display screen or other display device, which is not limited herein.

[0078] In actual application scenarios, the backlight module provided in the related art and the backlight module provided in the present embodiment can be compared through specific actual data.

[0079] As shown in FIGS. 1, 2 and 3, the backlight module provided in the related art can include a light guide plate 1, a backlight source 2, a side reflection sheet 3, a back plate 4 and a rubber pad 5. Figure 1 and Figure 2 As shown in FIGS. 1, 2 and 3, the backlight module provided in the related art can include a light guide plate 1, a backlight source 2, a side reflection sheet 3, a back plate 4 and a rubber pad 5.

[0080] wherein the distance D1 between the effective light-emitting area and the outer wall of the side plate of the back plate in the upper side frame area is A1+d1+b+s; A1 is the distance from the effective light-emitting area to the upper edge of the light guide plate, which is generally greater than or equal to 1.8 mm; d1 is the thickness of the side reflection sheet; s is the thickness of the back plate (which is at least 0.5 mm); b is the distance from the side reflection sheet to the inner wall of the back plate in the y direction, which is the sum of the expansion amount of the light guide plate in the y direction and the thickness of the rubber pad after compression at high temperature (which is at least 0.5 mm), minus the thickness of the side reflection sheet (which is generally 0.125 mm), wherein the expansion amount of the light guide plate in the y direction = the width of the light guide plate in the y direction × 0.3%, and b = the width of the light guide plate in the y direction × 0.3% + Min 0.5-0.125 (mm). In actual applications, for a 1.95-inch display screen, b = Min 0.495 mm, and D1 = Min 1.8 + 0.125 + Min 0.495 + Min 0.5 = Min 2.92 mm; and for a 2-4-inch display screen, b = Min 0.6 mm (the width of the light guide plate in the y direction is 75 mm), and D1 = Min 1.8 + 0.125 + Min 0.6 + Min 0.5 = Min 3.025 mm.

[0081] The left and right frame areas are narrowed in the following way: the thickness of the rubber pad of the left frame area is the same as the thickness of the rubber pad of the right frame area, and the expansion amount is equal. The distance D2 between the effective light-emitting area and the outer wall of the side plate of the back plate in the left frame area, and the distance D3 between the effective light-emitting area and the outer wall of the side plate of the back plate in the right frame area, D2=D3=A2+d1+c+s; wherein A2 is the distance from the effective light-emitting area to the left (or right) side of the light guide plate, generally more than 1.8 mm; c is the distance of the inner wall of the back plate in the x direction of the left (right) side reflective sheet, which is the expansion amount of a single side of the light guide plate in the x direction and the thickness of the rubber pad after being compressed at high temperature (Min 0.5 mm), minus the thickness of the side reflective sheet (usually 0.125 mm), the expansion amount of a single side of the light guide plate in the x direction is (the width of the light guide plate in the x direction x 0.3%) / 2, and c=(the width of the light guide plate in the x direction x 0.3%) / 2+Min 0.5-0.125 (mm). In actual application, for a 1.95-inch display screen, c=Min 0.435 mm, D2=D3=Min 1.8+0.125+Min 0.435+Min 0.5=Min 2.86 mm, and for a 2-4-inch display screen: c=Min 0.495 mm (note: the width of the light guide plate in the x direction is 80 mm), D2=D3=Min 1.8+0.125+Min 0.495+Min 0.5=Min 2.92 mm.

[0082] In the formula, the middle frame of the small-size display screen can be a middle iron frame and a middle rubber frame. The middle iron frame is thinner than the middle rubber frame, which can make the frame narrow. Specifically, the width Br1 of the upper frame area is D1+assembly gap+middle iron frame thickness, wherein the assembly gap is at least 0.075, and the middle iron frame thickness is usually 0.3 mm; and the width Br2 of the left or right frame area is D2(or D3)+assembly gap+middle iron frame thickness. In practical applications, for a 1.95-inch display screen: Br1=Min 2.92+Min 0.075+0.3=Min 3.295 mm, Br2=Min 2.86+Min 0.075+0.3=Min 3.235 mm, and the total width Br3 of the left and right frame areas is Br2×2=(Min 3.235)×2=Min 6.47 mm; for a 2-4-inch display screen: Br1=Min 3.025+Min 0.075+0.3=Min 3.4 mm, Br2=Min 2.92+Min 0.075+0.3=Min 3.295 mm, and the total width Br3 of the left and right frame areas is Br2×2=(Min 3.295)×2=Min 6.59 mm.

[0083] The backlight module provided by the embodiment of the present application has Figure 15 As shown in the formula, the frame area BB of the backlight module can have an upper frame area, a left frame area and a right frame area. The width (the distance from the effective light-emitting area to the outer side of the back plate) of each frame area can be calculated, and the width direction of the left and right frame areas can be set along the x direction, and the width direction of the upper frame area can be set along the y direction.

[0084] D1 = A1 + thickness of the first reflective sheet + e + thickness of the second reflective sheet d2 + s; A1 is greater than or equal to 1.8 mm; the thickness of the first reflective sheet can be 0.125 mm; e is the gap between the first reflective sheet and the second reflective sheet in the y direction, which meets the light guide plate high-temperature expansion requirement, i.e., e ≥ e', e' = light guide plate y direction expansion amount - second reflective sheet compression amount at high temperature, light guide plate y direction expansion amount = light guide plate y direction width × 0.3%, second reflective sheet compression amount at high temperature = 70% of double-sided adhesive thickness. In actual application, for a display screen size ≤ 2 inches, the thickness d2 of the second reflective sheet can be 0.125 mm, wherein the thickness of the reflective sheet is 0.075 mm, the thickness of the double-sided adhesive is 0.05 mm, and the e value is calculated for a 1.95-inch example: e' = (light guide plate y direction width × 0.3%) - (double-sided adhesive thickness 0.05 mm × 0.7) = 37.5 × 0.3% - 0.05 × 0.7 = 0.1125 - 0.035 = 0.0775 mm, e = 0.08 mm, e ≥ e', so D1 = A1 + 0.125 + e + d2 + Min 0.5 = Min 1.8 + 0.125 + 0.08 + 0.125 + Min 0.5 = Min 2.63 mm. For 2 inches < display screen size ≤ 4 inches, the thickness d2 of the second reflective sheet = reflective sheet thickness 0.075 mm + double-sided adhesive thickness 0.15 mm, d2 = 0.225 mm, e value calculation: e' = (light guide plate y direction maximum width 75 mm × 0.3%) - (double-sided adhesive thickness 0.15 mm × 0.7) = 75 × 0.3% - 0.15 × 0.7 = 0.225 - 0.105 = 0.12 mm, e value is 0.12 mm, e ≥ e', so D1 = A1 + 0.125 + e + d2 + Min 0.5 = Min 1.8 + 0.125 + 0.12 + 0.225 + Min 0.5 = Min 2.77 mm.

[0085] In the left and right border areas, D2 = D3 = A2 + thickness of the first reflective sheet + f + thickness of the second reflective sheet + s; A2 is greater than 1.8mm; f is the gap in the x-direction between the first and second reflective sheets. This gap must meet the high-temperature expansion requirements of the light guide plate, that is, f ≥ f', f' = unilateral expansion of the light guide plate in the x-direction - compression of the second reflective sheet at high temperature. Unilateral expansion of the light guide plate in the x-direction = (width of the light guide plate in the x-direction × 0.3%) / 2. Compression of the second reflective sheet at high temperature = 70% of the thickness of the double-sided adhesive. In practical applications, for displays ≤ 2 inches, the thickness d2 of the second reflective sheet can be 0.125mm, where the reflective sheet thickness is 0.075mm and the double-sided adhesive thickness is 0.05mm. Taking a 1.95-inch display as an example, the f value is calculated as follows: f' = (width of light guide plate in the x-direction × 0.3%) / 2 - (double-sided adhesive thickness 0.05mm × 0.7) = (40 × 0.3%) / 2 - 0.05 × 0.7 = 0.06 - 0.035 = 0.025mm. Taking f = 0.05 mm, f ≥ f', d2 = 0.125mm, therefore D2 = D3 = A2 + 0.125 + f + d2 + Min 0.5 = Min 1.8 + 0.125 + 0.05 + 0.125 + Min 0.5 = Min 2.6mm = 0.125mm; For displays 2 inches < 4 inches, d2 = reflector thickness 0.075mm + double-sided adhesive thickness 0.05mm, f value calculation: f' = (maximum width of light guide plate in x direction 80mm × 0.3%) / 2 - (double-sided adhesive thickness 0.05mm × 70%) = (80 × 0.3%) / 2 - 0.05 × 0.7 = 0.12 - 0.035 = 0.085mm, take f = 0.09 mm, satisfying f ≥ f', so D2 = D3 = A2 + 0.125 + f + d + Min 0.5 = Min 1.8 + 0.125 + 0.09 + 0.125 + Min 0.5 = Min 2.64mm.

[0086] The expansion of the light guide plate increases with the size of the display screen. For displays with a size of 2 inches or less and 4 inches or less, the expansion of the light guide plate in the y direction is relatively large. 0.15mm thick elastic double-sided tape can be used, and the total thickness of the adhesive on the second reflective sheet is 0.225mm, which facilitates the positioning of the light guide plate.

[0087] Among them, such as Figure 16As shown, the width of the upper side frame area Br1 = D1 + assembly gap L (Min 0.075) + middle iron frame thickness (commonly 0.3 mm); the width of the left (right) side frame area (single side): Br2 = D2 (D3) + assembly gap Min 0.075 + middle iron frame thickness. In actual application, for display screen size ≤ 2 inches, taking 1.95 inches as an example, Br1 = Min 2.63 + Min 0.075 + 0.3 = Min 3.005 mm, Br2 = Min 2.6 + Min 0.075 + 0.3 = Min 2.975 mm, the total width of the left and right side frame areas B3 = Br2 x 2 = (Min 2.975) x 2 = Min 5.95 mm; for 2 inches < display screen size ≤ 4 inches, Br1 = Min 2.77 + Min 0.075 + 0.3 = Min 3.145 mm, Br2 = Min 2.64 + Min 0.075 + 0.3 = Min 3.015 mm, the total width of the left and right side frame areas Br3 = Br2 x 2 = (Min 3.015) x 2 = Min 6.03 mm.

[0088] Therefore, the comparison of the frame area width of the backlight module in the embodiment of the present application with the frame area width in the related art can be shown in Table 1. As can be seen from Table 1, the width of the frame area of the backlight module in the embodiment is smaller than the width of the frame area of the backlight module in the related art, that is, the width of the frame of the display screen in the embodiment is smaller than the width of the frame of the display screen in the related art, and the narrow frame effect can be achieved in the embodiment.

[0089] Table 1

[0090]

[0091] In the display module provided by the above embodiment, as shown, Figure 17 The distance between the first reflective sheet on the light guide plate and the effective light emitting area is R' = A - a, A is the distance from the effective light emitting area to the edge of the light guide plate, the minimum value is 1.8 mm, a = 0.2 ± 0.2 mm, a is the distance from the first reflective sheet to the corner of the light guide plate ± assembly process error. Therefore, R' = Min 1.8 - (0.2 ± 0.2) = Min 1.6 mm, the larger R' is, the higher the corner brightness uniformity of the effective light emitting area is. The distance between the first reflective sheet on the light guide plate and the window of the middle frame can be T, T = R' - S', S' is the distance from the window of the middle frame to the effective light emitting area, generally 0.5 mm for small size display screen, so T = Min 1.6 - 0.5 = Min 1.1 mm.

[0092] The backlight module provided by the above embodiment can seal the gap between the rubber pad and the side reflective sheet in the related art, can avoid light leakage at this position, the first reflective sheet can reflect light back to the light guide plate basically completely, can ensure that the corner brightness of the light guide plate is consistent with the brightness of other areas, and can greatly improve the brightness uniformity of a small display screen, and the second reflective sheet on the sidewall of the back plate can seal the light leakage at the corner of the light guide plate, can effectively prevent corner light leakage, and can improve the corner display effect of the backlight module.

[0093] Obviously, various modifications and variations of the embodiments of the present application can be made by those skilled in the art without departing from the spirit and scope of the present application. Thus, it is intended that the present application include modifications and variations of the present application provided they come within the scope of the appended claims and their equivalents.

Claims

1. A backlight module, characterized in that, The backboard comprises a bottom plate and a plurality of side plates connected to the edges of the bottom plate, the plurality of side plates and the bottom plate form a containing space, the plurality of side plates comprise at least one first side plate and a plurality of second side plates; The light guide plate is located in the containing space and comprises a light entrance surface and a plurality of non-light entrance surfaces, the light entrance surface is opposite to the first side plate, and the plurality of non-light entrance surfaces are arranged opposite to the plurality of second side plates one by one; At least one lamp strip is fixed on the inner wall of the at least one first side plate one by one, and each lamp strip has a first assembly gap between the corresponding light entrance surface; A plurality of first reflective sheets are attached to the plurality of non-light entrance surfaces one by one; A plurality of positioning optical film sheets are attached to the inner walls of the plurality of second side plates, and the positioning optical film sheets have a second assembly gap between the first reflective sheets; The adjacent end portions of two adjacent second side plates cooperatively form a limiting corner portion, and a plurality of limiting corner portions can be cooperatively formed between a plurality of second side plates; The plurality of positioning optical film sheets can be divided into a plurality of film sheet groups, the plurality of film sheet groups are attached to the plurality of limiting corner portions one by one, each film sheet group comprises two positioning optical film sheets, and the two positioning optical film sheets are attached to the adjacent end portions of two adjacent second side plates respectively. An edge formed by the intersection of two non-light entrance surfaces has a light transmission area between the adjacent first reflective sheet, and the light transmission area is opposite to the positioning optical film sheet.

2. The backlight module of claim 1, wherein, In each film sheet group, the two positioning optical film sheets have a third assembly gap therebetween.

3. The backlight module of claim 1, wherein, The end portion of one positioning optical film sheet in the film sheet group abuts against the inner wall of the second side plate to cooperatively close the gap between the end portions of two adjacent second side plates.

4. The backlight module of claim 2, wherein, The distance between the surface of the positioning optical film sheet away from the bottom plate and the surface of the light guide plate adjacent to the bottom plate is a first distance, the distance between the surface of the light guide plate away from the bottom plate and the surface of the light guide plate adjacent to the bottom plate is a second distance, and the first distance is less than the second distance.

5. The backlight module of claim 1, wherein, The surface of the positioning optical film sheet adjacent to the bottom plate abuts against the bottom plate.

6. The backlight module of claim 5, wherein, The positioning optical film sheet is a second reflective sheet.

7. The backlight module according to any one of claims 1-6, wherein, The second reflective sheet is a self-adhesive reflective sheet, the second reflective sheet comprises double-sided adhesive tape and a reflective sheet attached to one side of the double-sided adhesive tape, the double-sided adhesive tape comprises a flexible substrate and pressure-sensitive adhesive located on both sides of the flexible substrate, and the reflective sheet comprises a foaming layer and a protective layer located on both sides of the foaming layer.

8. The backlight module of claim 7, wherein, The positioning optical film sheet is a light shielding sheet.

9. The backlight module of any of claims 1-6, wherein, The backboard is formed by sheet metal stamping.

10. The backlight module of claim 1, wherein, It also comprises a bottom reflective sheet and an optical film material, the bottom reflective sheet is located between the light guide plate and the bottom plate, and the optical film material is located on the side of the light guide plate away from the bottom plate.

11. The backlight module of claim 1, wherein, It also comprises a middle frame, the middle frame comprises a connecting frame and a bearing frame; 12. The backlight module of claim 11, wherein, The connecting frame is located outside the plurality of side plates of the backboard and is clamped with the plurality of side plates, and the connecting frame has a fourth assembly gap with the side plates; ​ The bearing frame is located on the side of the optical film material away from the light guide plate, and has a fourth assembly gap between the bearing frame and the optical film material.

13. The backlight module of claim 12, wherein, The middle frame is a middle plastic frame or a middle iron frame.

14. A display device comprising: The backlight module comprises the backlight module as claimed in any one of claims 1-13.

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