CN102966887A - Backlight module and display element - Google Patents

Abstract

A backlight module and a display element. The backlight module includes: a casing, an optical plate, a light source, a reflective sheet and an optical film. The optical plate is located in the housing and has a light-emitting surface, a light-incident surface, and a first side connected to the light-emitting surface. The light source is adjacent to the light incident surface. The reflective sheet is located between the housing and the optical plate and faces the opposite side of the light-emitting surface. The optical film faces the light-emitting surface and has an extension portion extending between the housing and the first side. Adopting the present invention has the technical advantage of reducing the width of the frame, and meets the current design requirements for backlight modules with small frames.

Description

Backlight module and display components

technical field

The present invention relates to a backlight module and its application structure, and in particular to a backlight module with a narrow frame structure and its application structure.

Background technique

With the vigorous development of the optoelectronic industry, liquid crystal displays (LCD for short) are widely used in televisions (Television; TV), screens (monitor), notebook computers (notebook; NB), personal digital assistants (personal digital assistant; PDA) and mobile phone (cell phone) and other electronic devices. However, the liquid crystal display is a non-self-illuminating flat-panel display, which needs to be illuminated by an external backlight or side light. Therefore, a backlight module is used as a light source in a liquid crystal display, and the high-brightness and high-uniformity illumination of the backlight module enables the liquid crystal display to efficiently display high-quality images.

Existing backlight modules generally include a light source, a backplane, an optical plate and an optical film. Among them, the light source and the optical board are placed in the backboard; the optical film is stacked flat on the optical board, and the hanging ears on the edge of the optical film are pierced through the positioning nail (pin) or the folding wall of the backboard way to fix it. However, a thermal expansion space needs to be reserved between the optical film and the back plate, otherwise the optical film will be warped due to extrusion, which will affect the image quality. In addition, in order to prevent the mounting lugs from being torn due to the expansion of the optical film, a certain width must be left at the mounting lugs passing through the positioning nails (pin) or the folding wall of the back panel. Therefore, if the backlight module is used to hide the frame of the non-visible area, the available space cannot be effectively reduced, which does not meet the current design requirements for the backlight module with a small frame.

Therefore, there is a need to provide a novel backlight module, which can effectively reduce the size of the positioning structure of the optical film, so as to solve the problem that the frame size of the existing backlight module cannot be effectively reduced, and at the same time improve the display quality of the liquid crystal display.

Contents of the invention

The present invention provides a backlight module and a display element to solve the problem that the frame size of the existing backlight module cannot be effectively reduced.

One aspect of the present invention is to provide a backlight module, including: a casing, an optical plate, a light source, a reflection sheet and a first optical film. The optical plate is located in the housing and has a light-emitting surface, a first side connected to the light-emitting surface, and a second side opposite to the first side. The light source is arranged between the casing and the optical plate. The reflection sheet is located between the housing and the optical plate, and faces the opposite side of the light-emitting surface. The first optical film, facing the light-emitting surface, has a first extension part extending between the casing and the first side surface.

In an embodiment of the present invention, the extension part is adhered and fixed on the first side by a double-sided adhesive tape or a single-sided adhesive tape.

In an embodiment of the present invention, the backlight module further includes a side panel fixed on the first side, and has a reflective surface facing the first side. In an embodiment of the present invention, the coverage of the single-sided tape exceeds the first extension portion, and the adhesive side of the single-sided tape faces the side panel.

In an embodiment of the present invention, the coverage of the single-sided tape exceeds the first extension portion, and the adhesive surface of the single-sided tape is a reflective surface.

In an embodiment of the present invention, the extension length of the first extension part is more than half of the thickness of the optical plate.

In an embodiment of the present invention, the light incident surface of the optical plate is located on the opposite side of the first side.

In an embodiment of the present invention, the light incident surface of the optical plate is located on the opposite side of the light output surface, and the light source is located between the optical plate and the reflection sheet.

In an embodiment of the present invention, the backlight module further includes a second optical film located between the first optical film and the light-emitting surface, and has a second extension extending between the casing and the first side surface , and does not overlap the first extension.

In an embodiment of the present invention, the first optical film further has a third extension extending between the casing and a third side surface of the optical plate.

In an embodiment of the invention, the first extending portion has an opening.

Another aspect of the present invention is to provide a display element, including: a backlight module and a display panel. Wherein, the backlight module includes a casing, an optical plate, a light source, a reflection sheet and a first optical film. The optical plate is located in the housing and has a light-emitting surface, a first side connected to the light-emitting surface, and a second side opposite to the first side. The light source is arranged between the casing and the optical plate. The reflection sheet is located between the housing and the optical plate, and faces the opposite side of the light-emitting surface. The first optical film faces the light-emitting surface and has a first extension part extending between the casing and the first side surface. The display panel is arranged on one side of the light emitting surface of the first optical film.

In an embodiment of the present invention, the extension part is adhered to the first side by double-sided adhesive tape.

In an embodiment of the present invention, the extension part is attached to the first side by a single-sided adhesive tape.

In an embodiment of the present invention, the backlight module further includes a side plate fixed on the first side, and the side plate has a reflective surface facing the first side. In an embodiment of the present invention, the coverage of the single-sided tape exceeds the first extension portion, and the adhesive side of the single-sided tape faces the side panel.

In an embodiment of the present invention, the coverage of the single-sided tape exceeds the first extension portion, and the adhesive surface of the single-sided tape is a reflective surface.

In an embodiment of the present invention, the extension length of the first extension part exceeds half of the thickness of the optical plate.

In an embodiment of the present invention, the display element further includes a light source adjacent to the second side surface.

In an embodiment of the present invention, the display element further includes a light source located between the optical plate and the reflection sheet.

In an embodiment of the present invention, the display element further includes a second optical film located between the first optical film and the light-emitting surface, and the second optical film has a second extension extending between the casing and the first optical film. between the sides and does not overlap the first extension.

In an embodiment of the present invention, the first optical film further has a third extension extending between the housing and the third side of the optical plate.

In an embodiment of the present invention, the first extending portion has an opening.

According to the above, embodiments of the present invention provide a backlight module and its application device, wherein the backlight module includes an optical film facing the light-emitting surface of the backlight module, and the edge of the optical film has an extension, which can be extended to the backlight module Between the back plate and the side of the optical plate for carrying the optical film; and the optical film can be fixed on the side of the optical plate by adhering the extension part with adhesive tape.

Because there is a thermal expansion space reserved between the backplane and the side of the optical plate, and the thickness of the optical film and the adhesive tape is quite thin. Therefore, the use of adhesive tape to fix the extension extending between the back plate and the side of the optical plate does not increase the size of the frame. Not only has the technical advantage of reducing the frame width, but also meets the current design requirements for small frame backlight modules. Moreover, due to the expansion coefficient of the optical plate, it is generally larger than that of the optical film. If the optical film is extended and fixed between the back plate and the side of the optical plate, the optical film will be stretched synchronously with the expansion of the optical plate with a larger expansion coefficient, and will be more flat. It will not cause the optical diaphragm to be warped by the back plate or torn by the mounting lugs due to insufficient expansion space. In this way, the problem of uneven brightness and darkness of the image quality caused by the film waving of the optical plate can be improved, which helps to improve the light uniformity of the backlight module and improve the display quality of the display.

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments, but not as a limitation of the present invention.

Description of drawings

FIG. 1A is a schematic cross-sectional view of an edge-lit backlight module with a narrow frame structure according to an embodiment of the present invention.

FIG. 1B is a schematic diagram of a partial three-dimensional structure of the backlight module shown in FIG. 1A .

FIG. 2 is a schematic cross-sectional view of a partial structure of an edge-lit backlight module with a narrow frame structure according to another preferred embodiment of the present invention.

3 is a schematic cross-sectional view of a partial structure of an edge-lit backlight module with a narrow frame structure according to yet another preferred embodiment of the present invention.

FIG. 4 is a schematic cross-sectional view of a direct-lit backlight module with a narrow frame structure according to yet another preferred embodiment of the present invention.

FIG. 5 is a schematic cross-sectional view of a display using a direct-lit backlight module with a narrow frame structure according to a preferred embodiment of the present invention.

FIG. 6 is a schematic cross-sectional view of a partial structure of an edge-lit backlight module with a narrow frame structure according to yet another preferred embodiment of the present invention.

Among them, reference signs:

40: Display 41: Display panel

100: Edge-lit backlight module 101: Housing

101a: bottom surface 101b: vertical wall

102: Optical plate 102a: Light-emitting surface

102b: second side 102c: first side

102d: Third side 102e: Fourth side

102f: Surface 103: Reflector

103a: reflective surface 104: first optical film

104a: first extension 104b: opening

104c: second extension 105: light source

106: Space 108: Sideboard

108a: reflective surface 109: single-sided tape

109a: Part of the adhesive layer 109b: Another part of the adhesive layer

110: Second optical film 110a: Extension

200: Edge-lit backlight module

209: Single-sided tape 209a: Adhesive layer

209b: Adhesive surface 300: Edge-lit backlight module

309: Double-sided tape 309a: Adhesive side

309b: Viscose surface 309c: Viscose layer

309d: Adhesive layer 400: Direct type backlight module

404: Optical diaphragm 404a: Extension

404b: extension part 405: light source

600: Backlight module 604: Optical film

604a: extension 608: side panel

608a: One side of the side panel 608b: The other side of the side panel

609a: Adhesive 609b: Adhesive

θ: angle H: extension length of the extension

T: side thickness S: tangent

Detailed ways

The present invention provides a backlight module with a narrow frame structure to solve the problem that the size of the frame of the existing backlight module cannot be effectively reduced. In order to make the above-mentioned and other purposes, features and advantages of the present invention more obvious and understandable, several backlight modules with narrow frame structures and display devices using such backlight modules are cited as preferred embodiments below, and In conjunction with the accompanying drawings, a detailed description is as follows.

Please refer to FIG. 1A and FIG. 1B . FIG. 1A is a schematic cross-sectional view of an edge-lit backlight module 100 with a narrow frame structure according to an embodiment of the present invention. FIG. 1B is a schematic diagram of a partial three-dimensional structure of the backlight module 100 shown in FIG. 1A . Wherein, FIG. 1A is roughly drawn along the tangent line S of FIG. 1B . However, for the sake of clarity, FIG. 1B does not show all components of the backlight module 100 , but some components are omitted.

The backlight module 100 includes: a casing 101 , an optical plate 102 , a reflection sheet 103 , a first optical film 104 and a light source 105 . The housing 101 has a bottom surface 101a, and a vertical wall 101b surrounding the bottom surface 101a. In this embodiment, the casing 101 is preferably a back iron frame of the backlight module 100 .

The optical board 102 is located in the casing 101 . In this embodiment, the optical plate 102 is the light guide plate of the backlight module 100, and has a light-emitting surface 102a, a light-incident surface, and a plurality of sides connected to the light-emitting surface 102a, such as the second side 102b, the first side 102c, the third side The side 102d and the fourth side 102e (as shown in FIG. 1B ). Wherein, the second side 102b opposite to the first side 102c is the light incident surface of the optical plate 102; the first side 102c is located on the side opposite to the second side 102b; the third side 102d connects the first side 102c and the second side 102b ; The fourth side 102e is located on the side opposite to the third side 102d.

The light source 105 is disposed adjacent to the light incident surface (the second side surface 102 b ) of the optical plate 102 . In this embodiment, the light source 105 is located in the casing 101 and adjacent to the second side 102b. The light emitted by the light source 105 enters the optical plate 102 through the second side surface 102 b and exits from the light emitting surface 102 a of the optical plate 102 . In some embodiments of the present invention, the light source 105 may be a light emitting diode (Light Emitting Diode; LED), a cold cathode tube (Cold Cathode fluorescent Lamp; CCFL), a hot cathode tube (Hot Cathode fluorescent Lamp; HCFL) or other suitable of Guangyuan. In this embodiment, it is preferable to use a light emitting diode as the light source 105 of the backlight module 100 .

In order to avoid light leakage, in some embodiments of the present invention, the backlight module 100 further includes a side plate 108, which is adjacent to and fixed on the first side 102c, has a reflective surface 108a facing the first side 102c, and can The light emitted from the inside of the optical plate 102 through the first side surface 102 c is reflected into the optical plate 102 .

The reflective sheet 103 is disposed in the housing 101 and located between the bottom surface 101 a of the housing 101 and the optical plate 102 . In some embodiments of the present invention, the reflective sheet 103 may be a metal plate; it may also be a metal layer that is directly plated on the bottom surface 101 a of the casing 101 . In this embodiment, the reflective sheet 103 is a metal plate with a reflective surface 103 a facing the surface 102 f of the optical plate 102 opposite to the light-emitting surface 102 a.

The first optical film 104 is disposed above the optical plate 102 and faces the light-emitting surface 102a, and has at least one extension, such as a first extension 104a, extending from the vertical wall 101b of the housing 101 and the first side surface of the optical plate 102 Between 102c. In some embodiments of the present invention, the first optical film 104 is placed flat on the light-emitting surface 102a of the optical plate 102, and the first extension portion 104a is extended outward from the edge of the first optical film 104. , and through bending, make it form an angle θ with the light-emitting surface 102a, and be accommodated between the vertical wall 101b and the first side 102c of the housing 101, providing the space 106 reserved for thermal expansion of the optical plate 102.

It should be noted that although in this embodiment, the angle θ formed by the first extension portion 104a of the first optical film 104 and the light-emitting surface 102a of the optical plate 102 is preferably 90°. However, in some embodiments of the present invention, in order to allow the space 106 to additionally accommodate other mechanisms, such as light guide plate stoppers (not shown), the first extension portion 104a of the first optical film 104 and the optical plate 102 The angle θ included by the light-emitting surface 102a can be adjusted to other angles.

In some embodiments of the present invention, the extension length H of the first extension portion 104a exceeds one-half of the thickness T of the optical plate 102; the maximum can be substantially the same height as the vertical wall 101b surrounding the bottom surface 101a of the housing 101 (ie The real value is equal to the depth of the shell 101). In some embodiments of the present invention, at least one opening 104b is formed in the center of the first extension part 104a, which helps to fix the first extension part 104a on the first side 102c or the vertical wall 101b of the casing 101 . For example, when using the single-sided adhesive tape 109 to stick and fix the first extension portion 104 a on the first side surface 102 c of the optical plate 102 , the setting of the opening 104 b can increase the covering area of the single-sided adhesive tape 109 . However, in some other embodiments of the present invention, the first extension portion 104a is not set to any opening (please refer to FIG. 6 ). In addition, for the convenience of folding and fixing, a bridging seam (not shown) may preferably be provided between the first extension portion 104 a and the edge of the first optical film 104 . In one embodiment of the present invention, the first extension 104a is attached to the side panel 108 outside the first side 102c by a single-sided adhesive tape 109 coated with an adhesive layer 109b (please refer to FIG. 1A again. ). Wherein, one of the length or width of the single-sided adhesive tape 109 is substantially larger than the extension length H of the first extension portion 104a, or substantially larger than the width of the first extension portion 104a. For example, in this embodiment, the coverage of the single-sided adhesive tape 109 exceeds the size of the first extension portion 104a. Wherein, a part of the adhesive layer 109a of the single-sided adhesive tape 109 faces and directly adheres to the side of the first extension 104a away from the side plate 108; another part of the adhesive layer 109b is not directly adhered to the first extension portion 104a. On the extension portion 104a, but directly adhere to the part of the side plate 108 that is not in contact with the first extension portion 104a (for example, a part of the adhesive layer 109b is directly adhered to the side plate 108 through the opening 104b), and then The first extension part 104 a is tightly attached to the side panel 108 .

In this embodiment, the first optical film 104 further includes another second extension portion 104c (as shown in FIG. Afterwards, it can be accommodated in the reserved space 106 between the vertical wall 101 b of the housing 101 and the third side 102 d of the optical plate 102 .

It should also be noted that the backlight module 100 may also include other optical films. For example, in this embodiment, in addition to the first optical film 104 , the backlight module 100 further includes a second optical film 110 located between the first optical film 104 and the light-emitting surface 102 a of the optical plate 102 . Like the first optical film 104, the second optical film 110 also has an extension 110a (as shown in FIG. In the reserved space 106 between one side 102c. The extension portion 110a of the second optical film 110 preferably does not overlap with the first extension portion 104a of the first optical film 104, so as to avoid occupying too much width of the accommodating space 106, which would otherwise be reserved for The expansion space of the optical plate 102 is greatly reduced.

In some embodiments of the present invention, the extension portion 110 a of the second optical film 110 may also be fixed by the aforementioned single-sided adhesive tape 109 . In order to fix the first extension 104 of the first optical film 104 and the extension 110a of the second optical film 110 on the side plate 108 at the same time, the length of the single-sided adhesive tape 109 preferably spans and covers the first between the extension 104 and the extension 110a. Moreover, the width of the single-sided adhesive tape 109 substantially exceeds the extension lengths of the first extension portion 104 and the extension portion 110a.

Please refer to FIG. 2 . FIG. 2 is a schematic cross-sectional view of a partial structure of an edge-lit backlight module 200 with a narrow frame structure according to another preferred embodiment of the present invention. Wherein, the structure of the backlight module 200 is roughly similar to that of the backlight module 100 , the only difference is that the backlight module 200 uses a different single-sided adhesive tape 209 to fix the first extension portion 104a. For the sake of clear description, the following diagrams will use the same reference numerals to denote the same components.

In this embodiment, the single-sided adhesive tape 209 for fixing the first extension portion 104a to the first side surface 102c of the optical plate 102 has an adhesive surface 209b coated with an adhesive layer 209a. Wherein, the adhesive surface 209b can be a reflective surface, which has the same effect as the side plate 108 shown in FIG. Therefore, the side plate 108 can be omitted directly, and the first extension portion 104 a is tightly attached to the first side surface 102 c of the optical plate 102 .

In addition, please refer to FIG. 3 . FIG. 3 is a partial structural cross-sectional view of an edge-lit backlight module 300 with a narrow frame structure according to yet another preferred embodiment of the present invention. Wherein, the structure of the backlight module 300 is roughly similar to the backlight module 100, the only difference is that: the backlight module 300 uses a double-sided tape 309 to fix the first extension 104a of the first optical film 104 on the first side 102c of the optical plate 102 superior. In this embodiment, the double-sided adhesive tape 309 has two adhesive surfaces 309a and 309b on the front and back, which are coated with adhesive layers 309c and 309d respectively; The first extension portion 104a faces the side of the first side surface 102c of the optical plate 102, and the size of the double-sided adhesive tape 309 is substantially equal to the size of the first extension portion 104a of the extension portion 104a.

Please refer to FIG. 6 . FIG. 6 is a partial structural cross-sectional view of an edge-lit backlight module 600 with a narrow frame structure according to yet another preferred embodiment of the present invention. Wherein, the structure of the backlight module 600 is roughly similar to that of the backlight module 300, the only difference is that: the optical film 604 used in the backlight module 600 is not provided with any opening in the extension part 604a; and the extension part 604a is formed by coating The side plate 608 covered with double-sided adhesives 609 a and 609 b is fixed on the first side 102 c of the optical plate 102 . In this embodiment, the side 608a of the side plate 608 coated with the adhesive 609a is pasted on the first side 102c of the optical plate 102; and the other side 608b of the side plate 608 coated with the adhesive 609b is then The extension 604a of the optical film 604 is attached.

It is worth noting that the above-mentioned narrow bezel structure design can also be applied to direct-lit backlight modules. For example, please refer to FIG. 4 . FIG. 4 is a schematic cross-sectional view of a direct-lit backlight module 400 with a narrow frame structure according to yet another preferred embodiment of the present invention. Wherein, the backlight module 400 includes: a casing 101 , an optical plate 102 , a reflection sheet 103 , an optical film 404 and a light source 405 .

The casing 101 has a bottom surface 101 a and a vertical wall 101 b surrounding the bottom surface 101 a of the casing 101 . In this embodiment, the casing 101 is preferably a back iron frame of the backlight module 400 . The optical board 102 is located in the casing 101 . In this embodiment, the optical plate 102 is a light guide plate or a diffuser plate of the backlight module 400, and has a light exit surface 102a, a light incident surface and a plurality of vertical walls connected to the light exit surface 102a, such as the second side 102b and the first side 102c . Wherein the second side 102b is located on a side opposite to the first side 102c. The light incident surface of the optical plate 102 is the surface 102f opposite to the first side 102a. The light source 405 is located between the optical plate 102 and the reflection sheet 103 . The light emitted by the light source 405 passes through the optical plate 102 and exits from the light emitting surface 102a.

The optical film 404 is disposed above the optical plate 102, faces the light-emitting surface 102a, and has at least one extension, such as extensions 404a and 404b. By bending, the extension part 404a can be extended between the vertical wall 101b of the housing 101 and the second side 102b of the optical board 102; 102c, and then accommodated in the reserved space 106 between the housing 101 and the optical board 102. In this embodiment, the backlight module 400 uses the double-sided tape 309 as shown in FIG. 3 to respectively fix the extensions 404 a and 404 b on the second side 102 b and the first side 102 c of the optical plate 102 . Since the structure of the double-sided adhesive tape 309 and its fixing method have been described in detail in FIG. 3 , they will not be repeated here.

The backlight modules of all the above embodiments, no matter they are edge-lit or direct-lit backlight modules, can be further applied to display elements. For example, please refer to FIG. 5 . FIG. 5 is a schematic cross-sectional view of a display 40 using a direct-lit backlight module 400 with a narrow frame structure according to an embodiment of the present invention. Wherein, the display 40 includes the direct type backlight module 400 and the display panel 41 shown in FIG. 4 . Wherein, the backlight module 400 includes a casing 101 , an optical plate 102 , a reflection sheet 103 and an optical film 404 .

The optical board 102 is located in the casing 101 and has a light-emitting surface 102a, a light-incoming surface and multiple sides, such as a second side 102b and a first side 102c. Wherein, the second side 102b and the first side 102c are connected with the light emitting surface 102a; and the second side 102b is opposite to the first side 102c. The light incident surface of the optical plate 102 is the surface 102f opposite to the light output surface 102a. The reflective sheet 103 is located between the housing 101 and the optical plate 102 and faces the opposite side of the light-emitting surface 102a. The light source 405 is located between the optical plate 102 and the reflection sheet 103 . The optical film 404 faces the light-emitting surface 102 a and has extensions 404 a and 404 b extending between the housing 101 and the second side 102 b and the first side 102 c respectively. The display panel 41 is disposed on one side of the backlight module 400 .

According to the above, embodiments of the present invention provide a backlight module and its application device, wherein the backlight module includes an optical film facing the light-emitting surface of the backlight module. Its edge has an extension, which can be extended between the back plate of the backlight module and the side of the optical plate for carrying the optical film; and the optical film can be fixed on the side of the optical plate by sticking the extension with adhesive tape superior.

Because the space between the back plate and the side of the optical plate used to carry the optical film is originally reserved for thermal expansion of the optical plate, and the size of the space is much larger than the thickness of an optical film. Therefore, accommodating the extension part in the reserved space does not take up too much space except for the thickness of the optical film, and does not need to increase the size of the frame. In addition, the use of tapes with a relatively small size to replace the existing positioning nails, backboard folding walls or hanging ears and other optical film positioning structures to fix the optical film not only has the technical advantage of reducing the width of the frame, but also conforms to the current Design requirements for backlight modules with small borders. Moreover, because the expansion coefficient of the optical plate is generally larger than that of the optical film, and the optical film is fixed on the side of the optical plate by at least one extension; The optical plate with a larger coefficient expands and is simultaneously stretched to be flatter. There will be no problems such as extrusion and warping of the backplane or tearing of the mounting lugs due to insufficient expansion space, which is more conducive to improving the light uniformity of the backlight module.

Certainly, the present invention also can have other various embodiments, without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and deformations according to the present invention, but these corresponding changes All changes and modifications should belong to the protection scope of the claims of the present invention.

Claims (22)

1. A backlight module, characterized in that, comprising: a shell; An optical plate, located in the housing, has a light-emitting surface, a light-incident surface, and a first side connected to the light-emitting surface; a light source adjacent to the light incident surface; a reflective sheet, located between the casing and the optical plate, and facing the opposite side of the light-emitting surface; and A first optical film, facing the light-emitting surface, has a first extension extending between the housing and the first side. 2 . The backlight module according to claim 1 , wherein the first extension portion is fixed on the first side by a double-sided adhesive tape or a single-sided adhesive tape. 3. The backlight module according to claim 2, further comprising a side plate disposed on the first side and having a reflective surface facing the first side. 4 . The backlight module according to claim 3 , wherein the single-sided tape has a coverage beyond the first extension portion, and an adhesive surface of the single-sided tape faces the side plate. 5 . The backlight module according to claim 2 , wherein the single-sided tape has a coverage beyond the first extending portion, and an adhesive surface of the single-sided tape is a reflective surface. 6 . The backlight module according to claim 1 , wherein the first extension portion has an extension length exceeding half of a thickness of the optical plate. 7. The backlight module according to claim 1, wherein the light-incident surface of the optical plate is located on a side opposite to the first side. 8 . The backlight module according to claim 1 , wherein the light incident surface of the optical plate is located on an opposite side of the light output surface, and the light source is located between the optical plate and the reflective sheet. 9. The backlight module according to claim 1, further comprising a second optical film, located between the first optical film and the light-emitting surface, having an extension extending between the casing and the light emitting surface Between the first side and not overlapping with the first extension. 10. The backlight module according to claim 1, wherein the first optical film further has a second extension extending between the housing and a third side surface of the optical plate. 11. The backlight module according to claim 1, wherein the first extension portion has an opening. 12. A display element, characterized in that it comprises: A backlight module, including: a shell; An optical plate, located in the housing, has a light-emitting surface, a first side connected to the light-emitting surface, and a second side opposite to the first side; a light source, located between the casing and the optical plate; a reflective sheet, located between the casing and the optical plate, and facing the opposite side of the light-emitting surface; and A first optical film, facing the light-emitting surface, has a first extension extending between the housing and the first side; and A display panel is arranged on one side of the backlight module. 13. The display element according to claim 12, wherein the extension part is fixed on the first side by a double-sided adhesive tape or a single-sided adhesive tape. 14. The display element according to claim 13, further comprising a side plate adjacent to the first side and having a reflective surface facing the first side. 15 . The display element according to claim 14 , wherein the single-sided tape has a range exceeding the first extending portion, and an adhesive surface of the single-sided tape faces the side plate. 16 . 16 . The display device according to claim 13 , wherein the single-sided adhesive tape has a range exceeding the first extension portion, and an adhesive surface of the single-sided adhesive tape is a reflective surface. 17. The display element according to claim 12, wherein the first extension portion has an extension length exceeding half of a thickness of the optical plate. 18. The display element according to claim 12, wherein the light source is adjacent to the second side surface. 19. The display element according to claim 12, wherein the light source is located between the optical plate and the reflective sheet. 20. The display element according to claim 12, further comprising a second optical film, located between the first optical film and the light-emitting surface, having a second extension extending from the housing between the body and the first side, and does not overlap with the first extension. 21. The display element according to claim 12, wherein the first optical film further has a third extension extending between the casing and a third side surface of the optical plate. 22. The display element according to claim 12, wherein the first extending portion has an opening.

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