CN201611056U - Backlight module and light emitting keyboard - Google Patents

Abstract

The utility model discloses a backlight module and a light emitting keyboard with the backlight module. The backlight module comprises a light guide board, a printed-circuit board and an light-emitting diode. The light guide board has a first surface and a second surface relative to the first surface, the printed-circuit board has a third surface and a fourth surface relative to the third surface, and the third surface faces to the second surface of the light guide board. A reflection layer is provided on the third surface of the printed-circuit board for reflecting the light ejected by the light guide board. The light-emitting diode is arranged on the printed-circuit board and is electrically connected to the circuit on the printed-circuit board, the light-emitting diode can transmits a light to the light guide board. The backlight module and light emitting keyboard of the utility model improves the light use ratio and realize the objective of using fewer light-emitting diode to achieve identical light-emitting efficiency, by using a reflecting plate or a reflection layer provided on its printed-circuit board to help light to reflect in the light guide board.

Description

Backlight module and illuminated keyboard

technical field

The utility model relates to a backlight module and a luminous keyboard, and in particular, the utility model relates to a backlight module and a luminous keyboard capable of increasing packaging reliability and reducing the number of light-emitting diodes.

Background technique

In recent years, due to the rapid development of the information industry, many users may use portable information devices, such as notebook computers or personal digital assistants, in different environments. In a low-light environment, such as a presentation with a projector, users may not be able to see the numbers and text marked on the keyboard keys clearly, making it difficult to work.

Please refer to FIG. 1 , which is a cross-sectional view of a light-emitting keyboard 1 in the prior art. As shown in FIG. 1 , the luminous keyboard 1 has a keyboard module 10 and a backlight module 12 , wherein the keyboard module 10 can be arranged on the backlight module 12 . The backlight module 12 has a light source 120 disposed in the light guide plate 122 . The light source 120 can be electrically connected to a printed circuit board (not shown in the figure) and controlled by the printed circuit board to emit light and enter the light guide plate 122 . The light travels in the light guide plate 122 and is reflected by the light guide plate 122 to be transmitted in the light guide plate 122 . A reflection component 1220 can be added on one side of the light guide plate 122 to reflect light, so that the light can pass through the light guide plate 122 and move toward the keyboard module 10 so that the user can observe the light.

The light source 120 used in FIG. 1 is an edge-lit type, that is, the light source 120 as a light-emitting diode is disposed on the side of the light guide plate 122 and receives light from the side.

However, the side-lit light source requires a higher number of light-emitting diodes, that is, the manufacturing cost of the side-lit light source is relatively high.

Utility model content

Therefore, an object of the present invention is to provide a top-firing or bottom-firing backlight module. Compared with an edge-lighting light source, the top-firing backlight module or the bottom-firing backlight module can use fewer light-emitting diodes to achieve the same luminous efficiency.

According to a specific embodiment, the backlight module of the present invention includes a light guide plate, a printed circuit board, and light emitting diodes. The light guide plate has a first surface and a second surface opposite to the first surface, and the printed circuit board has a third surface and a fourth surface opposite to the third surface, wherein the third surface of the printed circuit board faces the second surface of the light guide plate. surface, and a reflective layer is provided between the third surface of the printed circuit board and the second surface of the light guide plate. The light-emitting diodes are arranged on the printed circuit board to electrically connect the circuits thereon, and the light-emitting diodes can emit light to the light guide plate.

Wherein, the LED is disposed on the third surface of the printed circuit board.

Wherein, the light guide plate includes a recessed portion, and the LED is partially accommodated in the recessed portion.

Wherein, the printed circuit board includes a hole, and the LED is arranged on the fourth surface of the printed circuit board and corresponds to the hole, and the light emitted by the LED passes through the hole to the light guide plate.

Wherein, a reflection plate is further included, adjacent to the first surface of the light guide plate.

Wherein, the printed circuit board is a transparent printed circuit board, and the light emitted from the second surface of the light guide plate passes through the transparent printed circuit board, or the printed circuit board includes at least a first hole, and the light emitted from the second surface of the light guide plate The light part passes through the first hole of the printed circuit board.

Wherein, a mask is further included, adjacent to the fourth surface of the printed circuit board.

Wherein, a mask is further included, adjacent to the first surface of the light guide plate.

The reflective layer on the third surface of the printed circuit board can help the light guide plate to reflect, so the light emitted by the LED can travel in the light guide plate.

Another object of the present invention is to provide a luminous keyboard with a new type of backlight module, which can solve the problems of the prior art.

According to a specific embodiment, the luminous keyboard of the present invention includes a backlight module and a keyboard module. The backlight module further includes a light guide plate, a printed circuit board and light emitting diodes. The light guide plate has a first surface and a second surface opposite to the first surface, and the printed circuit board has a third surface and a fourth surface opposite to the third surface, wherein the third surface of the printed circuit board faces the second surface of the light guide plate. surface, and a reflective layer is provided between the third surface of the printed circuit board and the second surface of the light guide plate. The light-emitting diodes are arranged on the printed circuit board to electrically connect the circuits thereon, and the light-emitting diodes can emit light to the light guide plate. The keyboard module is arranged on the backlight module.

Wherein, the keyboard module includes a substrate, the substrate has a hole, and the keycap has a light-transmitting area, and the light of the backlight module illuminates the light-transmitting area through the hole; or the keyboard module includes a transparent substrate, and the keycap has a light-transmitting area. In the light area, the light of the light guide plate passes through the transparent substrate to irradiate the light transmission area.

Another object of the present invention is to provide a new type of backlight module, which can solve the problems of the prior art.

According to a specific example, the backlight module of the present invention includes a printed circuit board, a reflector, a light guide plate, a light emitting diode and a mask. The reflective plate is arranged corresponding to the first surface of the printed circuit board, and the reflective plate has a second surface facing the first surface of the printed circuit board. In addition, the reflective plate has a reflective surface opposite to the second surface and a first hole. The light guide plate is adjacent to the reflection surface of the reflection plate, and has a third surface facing the reflection surface of the reflection plate and a fourth surface opposite to the third surface. The light emitting diode is arranged on the printed circuit board and is electrically connected with the circuit on the printed circuit board. It is used for emitting light to the second surface of the reflection plate and passing through the first hole to reach the third surface of the light guide plate. The mask is adjacent to the fourth surface of the light guide plate, and is used for partially reflecting the light emitted from the fourth surface of the light guide plate.

Wherein, the LED is disposed on the first surface of the printed circuit board.

Wherein, the printed circuit board includes a second hole and a fifth surface opposite to the first surface, wherein the light emitting diode is arranged on the fifth surface of the printed circuit board and corresponds to the position of the second hole, the light emitting diode The emitted light passes through the second hole to the first hole of the reflective plate.

The reflective surface of the reflective plate can help the light guide plate to reflect, so the light emitted by the LED can travel in the light guide plate.

Another object of the present invention is to provide a new type of backlight module, which can solve the problems of the prior art.

According to a specific embodiment, the backlight module of the present invention includes a printed circuit board, a light guide plate, a reflection plate, a light emitting diode and a mask. The printed circuit board has a first surface and a second surface opposite to the first surface. The light guide plate is disposed opposite to the first surface of the printed circuit board, and has a third surface and a fourth surface opposite to the third surface, wherein the third surface faces the first surface. The reflective plate is adjacent to the light guide plate, and has a reflective surface facing the fourth surface of the light guide plate. The light emitting diode is arranged on the printed circuit board and can be used to emit light to the third surface of the light guide plate. The mask is close to the second surface of the printed circuit board to partially block light emitted from the second surface of the printed circuit board.

Wherein, the printed circuit board is a transparent printed circuit board, and the light emitted by the light guide plate is emitted through the transparent printed circuit board; or the printed circuit board includes at least a first hole, and the light emitted by the light guide plate is emitted through the first hole.

Wherein, the LED is disposed on the first surface of the printed circuit board.

Wherein, the printed circuit board has a second hole, the light emitting diode is arranged on the second surface of the printed circuit board and corresponds to the position of the second hole, and the light emitted by the light emitting diode passes through the second hole to the third surface of the light guide plate.

The reflective surface of the reflective plate can help the light guide plate to reflect, so the light emitted by the LED can travel in the light guide plate.

In order to make the above content of the present invention more obvious and understandable, the preferred embodiments will be described in detail below together with the accompanying drawings.

Description of drawings

FIG. 1 is a cross-sectional view of a light-emitting keyboard in the prior art.

FIG. 2A is a schematic diagram of a luminous keyboard according to a specific embodiment of the present invention.

FIG. 2B is a schematic diagram of the backlight module according to FIG. 2A .

FIG. 3 is a schematic diagram of a luminous keyboard according to another embodiment of the present invention.

FIG. 4 is a schematic diagram of a luminous keyboard according to another embodiment of the present invention.

FIG. 5 is a schematic diagram of a backlight module according to another embodiment of the present invention.

FIG. 6 is a schematic diagram of a backlight module according to another embodiment of the present invention.

Detailed ways

Please refer to FIG. 2A . FIG. 2A is a schematic diagram of a luminous keyboard 2 according to a specific embodiment of the present invention. As shown in FIG. 2A, the luminous keyboard 2 includes a backlight module 20 and a keyboard module 22, wherein the keyboard module 22 is arranged on the backlight module 20, and the light emitted by the backlight module 20 can be observed by the user through the keyboard module 22. light. The backlight module 20 shown in FIG. 2A can be regarded as a top-down type backlight module.

In this specific embodiment, the backlight module 20 may include a light guide plate 200 , a printed circuit board 202 and a light emitting diode 204 . The light guide plate has a first surface 2000 and a second surface 2002 opposite to each other, and the printed circuit board 202 has a third surface 2020 and a fourth surface 2022 opposite to each other. The third surface 2020 faces the second surface 2002 of the light guide plate 200 , and a reflective layer 2024 is disposed thereon to reflect light emitted from the light guide plate 200 . In practice, the reflective layer can be, but not limited to, white paint, metal film, aluminum plating or polymer. The light emitting diode 204 is disposed on the third surface 2020 of the printed circuit board 202 and is electrically connected to the circuit (not shown in the drawing) of the printed circuit board 202. The light emitting diode 204 can be controlled by the printed circuit board 202 to emit light to the light guide plate 200. Please note that only one light-emitting diode is shown in this embodiment, but in practice, the number of light-emitting diodes can be determined according to the needs of users or designers, and is not limited to this embodiment.

Since the light emitting diodes 204 of this embodiment are disposed on the third surface 2020 of the printed circuit board 202 , the light guide plate 200 may include a recess 2004 whose position corresponds to the position of the light emitting diodes 204 . When the backlight module 20 is assembled, the light guide plate 200 can be disposed on the printed circuit board 202, and the light emitting diodes 204 are partially accommodated in the recessed portion 2004, as shown in FIG. 2B, which shows the backlight module 20 according to FIG. 2A. schematic diagram.

Please refer to FIG. 2A again, the backlight module 20 may further include a cover 206 disposed between the light guide plate 200 and the keyboard module 22 . In practice, the mask 206 can partially reflect the light emitted from the first surface 2000 of the light guide plate 200 . The shield 206 has a light-transmitting area 2060 to allow light to pass through. The light-transmitting area 2060 can be made of transparent material or perforated to allow light to pass through. For example, the light-transmitting area 2060 in FIG. 2A is made of transparent material, and the light-transmitting area 2060 in FIG. 2B is a perforated hole.

In this embodiment, the light emitting diodes 204 can emit light toward the light guide plate 200 . The light travels through the light guide plate 200 and reaches the first surface 2000 of the light guide plate, wherein part of the light is reflected and part of the light passes through the first surface 2000 . The light passing through the first surface 2000 will reach the cover 206, and the cover 206 allows the light to penetrate to the keyboard module 22 in the light-transmitting area 2060 and absorb or reflect the light in other positions. Please note that in practice, this cover can also be omitted and the above-mentioned cover function can be completed by the iron plate structure of the keyboard module.

The light reflected by the first surface 2000 of the light guide plate 200 or reflected by the mask 206 will travel toward the printed circuit board 202 in the light guide plate 200 . When the light reaches the second surface 2002 of the light guide plate 200 or the reflective layer 2024 of the printed circuit board 202 , the light is reflected again and goes toward the keyboard module 22 .

With the above structure, the light emitting diodes can be arranged on the front of the light guide plate, and travel in the light guide plate in a reflective manner. Compared with the previous method of arranging the light source on the side of the light guide plate, the light emitted by the light source of the backlight module of this specific embodiment is also easily reflected and can be transmitted in the light guide plate, and it has higher packaging reliability and lower production costs.

In this specific embodiment, the keyboard module 22 may include a substrate 220 and a keycap 222 disposed on the substrate 220 , wherein the substrate 220 has a hole 2200 and the keycap 222 has a light-transmitting area 2220 . The light emitted by the light-emitting diode 204 can reach the substrate 220 after passing through the light guide plate 200 and the cover 206 , and can illuminate the light-transmitting area 2220 of the keycap 222 through the hole 2200 , further allowing the user located above the keycap 222 Light is observed. Please note that the light-transmitting design of the substrate is not limited to perforations, but depends on the needs of users or designers. For example, in another embodiment, the substrate can be made of a transparent material and is a transparent substrate, and the light emitted from the light guide plate can pass through the transparent substrate and illuminate the light-transmitting area of the keycap.

The light emitting diodes 204 of this embodiment are disposed on the third surface 2020 of the printed circuit board 202 , so when the backlight module 20 is assembled, the light guide plate 200 needs to be provided with a recessed portion 2004 to partially accommodate the light emitting diodes 204 . However, the location of the light emitting diodes (light emitting sources) is not limited to this specific embodiment.

Please refer to FIG. 3. FIG. 3 shows a schematic diagram of a light-emitting keyboard 3 according to another specific embodiment of the present invention. As shown in FIG. 3, the difference from the above specific embodiment lies in the backlight module 30 of this specific embodiment The printed circuit board 302 may include a hole 3026 . The LED 304 is disposed on the fourth surface 3022 of the printed circuit board 302 and corresponds to the position of the hole 3026 . The light-emitting surface of the LED 304 in this embodiment faces the hole 3026 , so the emitted light passes through the hole 3026 to reach the light guide plate 300 . Other units of the light-emitting keyboard 3 in this specific embodiment are substantially the same as the corresponding units in the above-mentioned specific embodiment, so details will not be repeated here. Since the light-emitting diodes 304 are disposed on the fourth surface 3022 of the printed circuit board, the light guide plate 300 does not need to provide additional recesses to accommodate the light-emitting diodes 304 . In addition, the mask 306 has a light-transmitting area 3060 to allow light to pass through. Similarly, in practice, the light-transmitting area 3060 can use perforated holes or transparent materials to allow light to pass through. In this specific embodiment, the light-transmitting area 3060 is a perforated hole.

Please refer to FIG. 4 . FIG. 4 is a schematic diagram of a luminous keyboard 4 according to another embodiment of the present invention. As shown in FIG. 4 , the backlight module 40 of the luminous keyboard 4 includes a light guide plate 400 , a printed circuit board 402 and a light emitting diode 404 . Each unit of the backlight module 40 in this specific embodiment is substantially the same as the corresponding unit in the above specific embodiment, so details will not be repeated here. The backlight module 40 further includes a reflection plate 406 adjacent to the first surface 4000 of the light guide plate 400 , and the keyboard module 42 is located on the fourth surface 4022 of the printed circuit board 402 . The backlight module 40 shown in FIG. 4 can be regarded as a drop-down type backlight module.

In this specific embodiment, the light emitting diode 404 is electrically connected to the printed circuit board 402, and the light emitting diode 404 can be accommodated in the recessed portion 4004 of the light guide plate 400, and the light emitted by the light emitting diode 404 enters the light guide plate 400, when the light enters the light guide plate 400 When the light plate 400 travels to the first surface 4000 of the light guide plate 400, part of the light will be reflected and part of the light will pass through the light guide plate 400, and then the light that penetrates the light guide plate 400 will be reflected by the reflector 406 and return to the light guide plate 400. The light guide plate 400. Please note that in practice, the reflection plate can also be directly disposed on the first surface of the light guide plate to directly reflect most of the light, so the light does not need to go out of the light guide plate to go to the reflection plate.

The light reflected by the reflective plate 406 travels toward the printed circuit board 402 in the light guide plate 400 , and is reflected by the second surface 4002 of the light guide plate 400 or the reflective layer 4024 , so the light can be transmitted in the light guide plate 400 . In addition, the reflective layer 4024 has a light-transmitting area 40240 to allow light to pass through. The light-transmitting area 40240 can use holes or transparent materials to allow light to pass through. The printed circuit board 402 can be respectively provided with first holes 4028 corresponding to the light-transmitting regions 40240 , so that light can penetrate the printed circuit board 402 through the first holes 4028 and reach the keyboard module 42 . Please note that in practice, the printed circuit board can also be made of a transparent material to be a transparent printed circuit board, so there is no need to additionally provide the first hole for the light to pass through.

Likewise, in another specific embodiment, the light emitting diodes can also be disposed on the fourth surface of the printed circuit board and correspond to the second hole on the printed circuit board. The light emitted by the LED passes through the second hole and reaches the light guide plate, and the light is reflected by the first surface of the light guide plate or the reflective plate and then travels toward the printed circuit board, and then can be reflected by the second surface of the light guide plate or the reflective layer . At a specific position, the reflective layer can allow light to pass through, and the printed circuit board can be provided with a first hole corresponding to the specific position for the light to pass through. In addition, the printed circuit board can be made of transparent material to be a transparent printed circuit board, so there is no need to additionally provide the first hole and the second hole for light to pass through.

Same as the above specific embodiment, the light emitted by the light emitting diode 404 of this specific embodiment penetrates the printed circuit board 402 to reach and pass through the keyboard module 42, and the user can observe through the light-transmitting area 4220 of the keycap 422 light.

The reflective layer is arranged on the above-mentioned printed circuit board to help the light reflect in the light guide plate, and the reflective plate can also replace the reflective layer. Please refer to FIG. 5 , which is a schematic diagram of a backlight module 50 according to another embodiment of the present invention. As shown in FIG. 5 , the backlight module 50 includes a printed circuit board 500 , a reflector 502 , a light guide plate 504 , LEDs 506 and a cover 508 . The printed circuit board 500 has a first surface 5000 , the reflector 502 is disposed corresponding to the first surface 5000 , and has a second surface 5020 facing the first surface 5000 of the printed circuit board 500 , a reflective surface R1 and a first hole 5022 . The light guide plate 504 is adjacent to the reflective plate 502 , and has a third surface 5040 facing the reflective surface R1 of the reflective plate 502 and a fourth surface 5042 . The mask 508 is adjacent to the fourth surface 5042 of the light guide plate 504 . The light emitting diode 506 can be disposed on the first surface 5000 of the printed circuit board 500 and electrically connected to the circuit on the printed circuit board 500 . The LED 506 is electrically connected to the printed circuit board 500 , and the LED 506 can be accommodated in the recess 5044 of the light guide plate 504 .

The light emitted by the light emitting diode 506 can pass through the first hole 5022 of the reflector 502 and reach the third surface 5040 of the light guide plate 504, and then, the light can be reflected by the third surface 5040, the fourth surface 5042 or the shield 508. Proceed towards reflective plate 502 . The reflective surface R1 of the reflective plate 502 re-reflects the light reflected by the third surface 5040 , the fourth surface 5042 or the mask 508 , and makes it travel toward the mask 508 . In practice, the cover 508 has a light-transmitting area 5080 to allow light to pass through, so that the light can reach the keyboard module. Similarly, in practice, the light-transmitting area 5080 can be made of transparent material or perforated to allow light to pass through. In this embodiment, the light-transmitting area 5080 is made of transparent material.

Similarly, the light-emitting diodes of this specific embodiment can also be arranged on the fifth surface of the printed circuit board opposite to the first surface in practice, and the light emitted by it can pass through the second hole or the second hole arranged on the printed circuit board. The printed circuit board itself is a transparent material and reaches the reflector.

Please refer to FIG. 6 , which is a schematic diagram of a backlight module 60 according to another embodiment of the present invention. As shown in FIG. 6 , the backlight module 60 includes a printed circuit board 600 , a reflector 602 , a light guide plate 604 , LEDs 606 and a mask 608 . The printed circuit board 600 has a first surface 6000 and a second surface 6002 , the light guide plate 604 has a third surface 6040 facing the first surface 6000 of the printed circuit board 600 , and a fourth surface 6042 opposite to the third surface 6040 . The reflective plate 602 is adjacent to the light guide plate 604 and its reflective surface R2 faces the fourth surface 6042 of the light guide plate 604 . The mask 608 is adjacent to the second side 6002 of the printed circuit board 600 . The light emitting diode 606 can be disposed on the first surface 6000 of the printed circuit board 600 and electrically connected to the circuit on the printed circuit board 600 . The LED 606 is electrically connected to the printed circuit board 600 , and the LED 606 can be accommodated in the recess 6044 of the light guide plate 604 .

The light emitted by the LED 606 can pass through the light guide plate 604 and be reflected by the third surface 6040 , the fourth surface 6042 of the light guide plate 604 and the reflective surface R2 of the reflective plate 602 . In this embodiment, the printed circuit board 600 is a transparent printed circuit board, therefore, the reflected light can be reflected by the third surface 6040 of the light guide plate 604 and the mask 608 . Through the reflection plate 602 and the shield 608 , the light can be reflected and travel in the light guide plate 604 . In addition, in practice, the cover 608 has a light-transmitting area 6080 to allow light to pass through, so that the light can reach the keyboard module. Similarly, the light-transmitting area 6080 can be made of transparent material or perforated to allow light to pass through. In this embodiment, the light-transmitting area 6080 is made of transparent material.

To sum up, the backlight module of the present invention can help light reflection through the reflection plate or the reflection layer provided on the printed circuit board. Therefore, the backlight module structure of the present invention can be provided with a light source on the front of the light guide plate. Compared with the prior art, the backlight module of the present invention not only has the advantage of being easily reflected and can be transmitted in the light guide plate, but also has higher package reliability and lower production cost of the positive light source.

From the above detailed description of the preferred embodiments, it is hoped that the features and spirit of the present utility model can be described more clearly, and the scope of the claims of the present utility model is not limited by the preferred embodiments disclosed above. On the contrary, the intention is to cover various changes and arrangements with equivalents within the scope of the claims of the present utility model.

Claims (17)

1. A backlight module, suitable for luminous keyboards, is characterized in that the backlight module comprises: The light guide plate has a first surface and a second surface opposite to the first surface; The printed circuit board has a third surface and a fourth surface opposite to the third surface, the third surface faces the second surface of the light guide plate and is between the third surface and the second surface of the light guide plate has a reflective layer; and The light emitting diode is arranged on the printed circuit board and electrically connected with the circuit on the printed circuit board, wherein the light emitting diode emits a light to the light guide plate. 2. The backlight module as claimed in claim 1, wherein the LED is disposed on the third surface of the printed circuit board. 3. The backlight module as claimed in claim 1, wherein the light guide plate comprises a recess, and the light emitting diode is partially received in the recess. 4. The backlight module according to claim 1, wherein the printed circuit board includes a hole, and the light emitting diode is arranged on the fourth surface of the printed circuit board and corresponds to the position of the hole, and the light emitting diode The emitted light passes through the hole to the light guide plate. 5. The backlight module as claimed in claim 1, further comprising a reflective plate adjacent to the first surface of the light guide plate. 6. The backlight module according to claim 5, wherein the printed circuit board is a transparent printed circuit board, the light emitted from the second surface of the light guide plate passes through the transparent printed circuit board, or the printed circuit board Containing at least a first hole, part of the light emitted by the second surface of the light guide plate passes through the first hole of the printed circuit board. 7. The backlight module as claimed in claim 5, further comprising a mask adjacent to the fourth surface of the printed circuit board. 8. The backlight module according to claim 1, further comprising a mask, adjacent to the first surface of the light guide plate, the mask is used for partially reflecting the light emitted from the first surface. 9. A luminous keyboard, characterized in that it comprises: The backlight module according to any one of claims 1 to 8; and The keyboard module is arranged on the backlight module. 10. The luminous keyboard according to claim 9, wherein the keyboard module comprises a substrate, the substrate has a hole, the keycap has a light-transmitting area, and the light of the backlight module illuminates the light-transmitting area through the hole or the keyboard module includes a transparent substrate, the keycap has a light-transmitting area, and the light of the light guide plate illuminates the light-transmitting area through the transparent substrate. 11. A backlight module, characterized in that it comprises: a printed circuit board having a first side; a reflective plate, disposed corresponding to the first surface, the reflective plate has a second surface facing the first surface, a reflective surface opposite to the second surface, and a first hole; a light guide plate, adjacent to the reflective surface of the reflective plate, the light guide plate has a third surface facing the reflective surface and a fourth surface opposite to the third surface; a light emitting diode, arranged on the printed circuit board and electrically connected to the circuit on the printed circuit board, the light emitted by the light emitting diode passes through the first hole to reach the third surface; and The mask is adjacent to the fourth surface, and the mask is used for partially reflecting the light emitted from the fourth surface of the light guide plate. 12. The backlight module as claimed in claim 11, wherein the LED is disposed on the first surface of the printed circuit board. 13. The backlight module according to claim 11, wherein the printed circuit board comprises a second hole and a fifth surface opposite to the first surface, wherein the light emitting diode is disposed on the fifth surface of the printed circuit board On the surface and corresponding to the position of the second hole, the light emitted by the LED passes through the second hole to the first hole of the reflective plate. 14. A backlight module, characterized in that it comprises: a printed circuit board having a first side and a second side opposite the first side; a light guide plate, disposed relative to the first surface, the light guide plate has a third surface facing the first surface and a fourth surface opposite the third surface; a reflective plate having a reflective surface facing the fourth surface of the light guide plate; a light emitting diode arranged on the printed circuit board, the light emitting diode emits light to the third surface of the light guide plate; and The mask is adjacent to the second surface, and the mask is used for partially blocking the light emitted from the second surface of the printed circuit board. 15. The backlight module according to claim 14, wherein the printed circuit board is a transparent printed circuit board, and the light emitted by the light guide plate is emitted through the transparent printed circuit board; or the printed circuit board includes at least a first hole , the light emitted by the light guide plate exits through the first hole. 16. The backlight module as claimed in claim 14, wherein the LED is disposed on the first surface of the printed circuit board. 17. The backlight module according to claim 14, wherein the printed circuit board has a second hole, the LED is arranged on the second surface of the printed circuit board and corresponds to the position of the second hole, and The light emitted by the LED passes through the second hole to the third surface of the light guide plate.

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