TWI847765B - Backlight module and keyboard thereof - Google Patents

Abstract

A backlight module is applied to providing light to a plurality of keyswitches of a keyboard. Each keyswitch has a cap and an elastic member abutting against the cap. The backlight module includes a membrane circuit board and a light guide plate. The membrane circuit board has a light emitting diode corresponding to the keyswitch. The light emitting diode is located at a side of the elastic member and emits light to the cap. The light guide plate is disposed on the membrane circuit board. The light guide plate has a slot hole for containing the light emitting diode and has a through hole corresponding to the elastic member. An optical microstructure is formed on the light guide plate for guiding light of the light emitting diode to be incident to the cap. The elastic member passes through the through hole to be disposed on the membrane circuit board.

Description

Backlight module and keyboard

The present invention relates to a backlight module and a keyboard, and more particularly to a backlight module and a keyboard that use a perforation and a slot of a light guide plate to respectively accommodate an elastic reset member and a light-emitting diode located on one side of the elastic reset member, and use an optical microstructure to guide light to be incident on a keycap.

In terms of current personal computer usage habits, the keyboard is one of the indispensable input devices for inputting text, symbols or numbers. Not only that, all consumer electronic products that we come into contact with in daily life or large-scale processing equipment used in the industrial sector need to be equipped with a key structure as an input device to operate the above-mentioned electronic products and processing equipment.

With the advancement of technology and the rise of environmental awareness, keyboard design has gradually developed in the direction of being lightweight, environmentally friendly and easy to recycle. However, keyboards often use a heavier metal base to connect multiple scissor-foot lift mechanisms (about 90) to support the keycaps connected to them so that they can move up and down relative to the metal base. This not only takes a lot of time to separate the scissor-foot lift mechanism from the metal base when disassembling and recycling the keyboard, affecting the recycling convenience of the keyboard, but the configuration of the above metal base is also not conducive to the lightweight design of the keyboard.

In addition, when users choose a keyboard, in addition to the basic input function, the keyboard's visual effect is also important to users. Backlit keyboards are currently available on the market. The common backlight design is to directly configure multiple LEDs corresponding to each key under the bottom plate, so that the LEDs can emit light to the corresponding characters on the keycaps to produce a character lighting effect. However, since the light emitted upward by the LED will directly hit the keys, it often causes the characters to be too bright, thereby affecting the uniformity of the keyboard keys and the visual aesthetics during use.

Therefore, one of the purposes of the present invention is to provide a backlight module and a keyboard that use the through hole and slot of the light guide plate to respectively accommodate the elastic reset member and the LED located on one side of the elastic reset member and use the optical microstructure to guide the light to be incident on the key cap, so that the light emitted by the LED can be more evenly incident on the middle character and the side characters on the key cap, so as to avoid the problem that the brightness of the middle character is too bright but the brightness of the side characters is insufficient.

According to an embodiment, the backlight module of the present invention is suitable for providing light to a plurality of key bodies of the keyboard, each key body has a key cap and an elastic reset member, the elastic reset member abuts against the key cap, and the backlight module includes a thin film circuit board and a light guide plate. The thin film circuit board is provided with at least one light emitting diode at a position corresponding to the key body, the at least one light emitting diode is located on at least one side of the elastic reset member and emits light to the key cap. The light guide plate is disposed on the thin film circuit board. The light guide plate has at least one slot for accommodating the at least one light emitting diode and has a through hole corresponding to the elastic reset member. An optical microstructure is formed on the light guide plate to guide the light of the at least one light emitting diode to be incident on the key cap. The elastic reset member passes through the through hole to be disposed on the thin film circuit board.

According to another embodiment, the keyboard of the present invention comprises a plurality of key bodies, a transparent bottom plate, a thin film circuit board, and a light guide plate. Each key body has a key cap, a lifting mechanism, and an elastic reset member, the lifting mechanism can be movably connected to the key cap, and the elastic reset member abuts the key cap. The transparent bottom plate is formed with a first through hole corresponding to the position of each elastic reset member, and each lifting mechanism can be movably connected to the plastic bottom plate so that each key cap can move up and down relative to the transparent bottom plate. The thin film circuit board is arranged under the transparent bottom plate and at least one light emitting diode is arranged at a position corresponding to the key body. The at least one light emitting diode is located on at least one side of the elastic reset member and emits light to the key cap. The light guide plate is arranged between the thin film circuit board and the transparent bottom plate. The light guide plate has a slot hole for accommodating the at least one light emitting diode and a second through hole corresponding to the elastic reset member. An optical microstructure is formed on the light guide plate to guide the at least one light emitting diode to be incident on the key cap. The elastic reset member passes through the first through hole and the second through hole to be arranged on the thin film circuit board.

By using the above-mentioned perforations and slots of the light guide plate to respectively accommodate the elastic reset member and the LED located on one side of the elastic reset member and using an optical microstructure to guide the light to be incident on the key cap, the light emitted by the LED can be more evenly incident on the middle character and the side characters on the key cap to avoid the problem of the middle character being too bright but the side characters being insufficiently bright, thereby producing a uniform lighting effect of the characters on the key cap.

The advantages and spirit of the present invention can be further understood through the following detailed description of the invention and the attached drawings.

10: Keyboard

11: Backlight module

12: Button body

14: Base plate

16: Thin film circuit board

18: Key caps

19: Linkage rod

20: Lifting mechanism

22: Elastic return member

24: First piercing

26: Connection structure

28: Hook arm

30: Loading base

31: snap-fit hole structure

32: Hole

33: Ribs

34: Conductive contact point

36: Conductive actuator column

38: Escape hole

40: LED

42: Light guide plate

44: Slot

46: Avoidance hole

48: Second piercing

50:Optical microstructures

52, 56, 60: Ridge-shaped ink layer

54, 58: Reflective ink layer

62: Ring-shaped adhesive layer

64:Fixed glue layer

D1: Fastening direction

D2: Disassembly direction

P: Projection profile

S1: middle character

S2: Side characters

R1: Low beam area

R2: Far beam area

Figure 1 is a top view of a keyboard according to one embodiment of the present invention.

Figure 2 is a schematic diagram of a partial cross section of the keyboard in Figure 1.

Figure 3 is a three-dimensional schematic diagram of the base plate of Figure 2.

Figure 4 is a partially enlarged top perspective view of the light guide plate in Figure 2.

Figure 5 is a schematic diagram of the ink layer configuration of the base plate in Figure 2.

Figure 6 is a schematic diagram of the ink layer configuration of the thin film circuit board in Figure 2.

Figure 7 is a partially enlarged top view of the light guide plate's adhesive layer configuration in Figure 2.

The following content will be accompanied by drawings to illustrate the technical content of the present invention through specific concrete embodiments. People familiar with this technology can easily understand other advantages and effects of the present invention from the content disclosed in this manual. The present invention can also be implemented or applied through other different specific embodiments. The details in this manual can also be modified and changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. In particular, the proportional relationship and relative position of each element in the diagram (such as the number, formation position and proportional size of the hook arm, ink layer, optical microstructure and characters) are only for exemplary purposes and do not represent the actual implementation of the present invention.

Please refer to FIG. 1 and FIG. 2. FIG. 1 is a top view of a keyboard 10 according to an embodiment of the present invention, and FIG. 2 is a partial cross-sectional view of the keyboard 10 of FIG. 1. The keyboard 10 can be preferably applied to an electronic device generally having an opening and closing structure composed of an upper cover and a lower housing or an electronic device having a key input function (such as a notebook computer, but not limited thereto), so that the user can press and execute As shown in FIG. 1 and FIG. 2, the keyboard 10 includes a plurality of key bodies 12, a bottom plate 14, and a thin film circuit board 16. Each key body 12 may have a key cap 18, a lifting mechanism 20, and an elastic reset member 22. A first through hole 24 may be formed at a position of the bottom plate 14 corresponding to each elastic reset member 22, and the thin film circuit board 16 is disposed under the bottom plate 14. The lifting mechanism 20 may preferably be a scissor foot mechanism (but not limited thereto, it may also adopt other common key lifting mechanisms, such as a butterfly wing lifting mechanism) and may be movably connected to the key cap 18 to support the key cap 18 to move up and down relative to the bottom plate 14 for the user to perform a pressing input operation. The elastic reset member 22 abuts against the key cap 18 and passes through the corresponding first through hole 24 on the bottom plate 14 to be disposed on the thin film circuit board 16. Through the above design, when the key cap 18 is pressed by external force, the elastic reset member 22 will be compressed and deformed to press against the triggering thin film circuit board 16 to generate a corresponding key signal, so that the keyboard 10 can perform the function that the user wants to input; on the other hand, when the external force is released, the elastic reset member 22 can use the elastic restoring force stored when it is pressed to help the key cap 18 return to its initial position, thereby producing the effect that the key cap 18 can automatically return to its original position, so that the user can perform subsequent pressing operations.

For a detailed description of the structural design of the base plate 14, please refer to FIG. 1, FIG. 2 and FIG. 3. FIG. 3 is a three-dimensional schematic diagram of the base plate 14 of FIG. 2. As can be seen from FIG. 2 and FIG. 3, the bottom plate 14 can preferably be formed of a light-transmitting plastic bottom plate by a plastic injection molding process, whereby the bottom plate 14 corresponding to each lifting mechanism 20 can be formed in an integral manner with at least one connecting structure 26 (four lifting mechanisms 20 corresponding to the key body 12 are shown in FIG. 3, but not limited thereto), and the connecting structure 26 can be movably connected to the lifting mechanism 20 (the relevant description of the movable connection design is common in the prior art and will not be repeated here), so that the key cap 18 can move up and down relative to the bottom plate 14 for the user to perform subsequent pressing input operations. In this embodiment, a plurality of hook arms 28 (the number is preferably greater than 40 to improve the assembly strength of the bottom plate 14, but not limited to this number) can be formed by extending downward from the bottom plate 14 in an integrally formed manner, whereby the plurality of hook arms 28 can pass through the thin film circuit board 16 to be snapped onto a plurality of snap hole structures 31 formed on a supporting base 30 of a computer device (not shown in the figure, such as a laptop), so that the keyboard 10 can be detachably mounted on the above-mentioned computer device.

In more detail, as can be seen from FIG. 2, when the user wants to assemble the keyboard 10, the user only needs to press down the keyboard 10 so that the plurality of hook arms 28 are hooked in the plurality of hook hole structures 31 in the locking direction D1, thereby quickly and conveniently completing the assembly operation of installing the keyboard 10 on the supporting base 30; on the other hand, when the user wants to disassemble the keyboard 10, the user only needs to open the bottom plate 14 in the disassembly direction D2 (opposite to the locking direction D1) so that the plurality of hook arms 28 can be separated from the plurality of hook hole structures 31 in the disassembly direction D2, thereby allowing the bottom plate 14 together with the key body 12 disposed thereon to be disassembled from the supporting base 31 for subsequent maintenance or disassembly and recycling. It should be noted that, as shown in FIG. 3, the position of the bottom plate 14 corresponding to the hook arm 28 may have a hole 32, and a rib 33 may be suspended in the hole 32 and connected to the hook arm 28. Thus, the present invention can increase the elasticity of the hook arm 28 through the above-mentioned rib suspension design, so that the user can complete the buckling operation of the hook arm 28 more time-saving and labor-saving, thereby further improving the convenience of assembly and disassembly of the bottom plate 14.

As for the environmental protection and recyclability of the keyboard 10, it can be seen from FIG. 1 that at least one of the plurality of key bodies 12 on the keyboard 10 (in FIG. 1, only the key body 12 (blank key) located at the bottom side of the keyboard 10 is used as an example for description, and the relevant description of the remaining key bodies equipped with metal connecting rods can be inferred in the same way) can further include at least one metal connecting rod 19 (in FIG. 1, only one is shown and is simplified by a dotted line, but it is not limited to this, and its metal connecting rod 19 is also shown in FIG. 1). The number of connecting rods can be determined according to the actual application of the keyboard 10). The metal connecting rod 19 is arranged under the key cap 18 and can adopt the connecting rod design commonly used on keyboards to increase the structural synchronization and operational sensitivity of the keyboard 10 when pressing a longer key (such as a multiple key). As for the structural design of the metal connecting rod 19 and the connection design of the metal connecting rod 19 and the key cap 18, it is commonly seen in the prior art and will not be repeated here. In addition to the above-mentioned configuration of the metal connecting rod 19, the remaining structures of the multiple key bodies 12 of the keyboard 10 (such as the key cap 18, the lifting mechanism 20, and the elastic reset member 22, etc.) are all composed of recyclable plastic materials, so that the entire keyboard 10 is composed of a high proportion of plastic materials (such as 95%). In this way, after the base plate 14 is disassembled from the supporting base 31 and the metal connecting rod 19 is removed, the disassembly and recycling of the keyboard 10 can be completed quickly, thereby greatly improving the environmental protection and recyclability of the keyboard 10. At the same time, the design of the plastic transparent base plate is also conducive to the lightweight design of the keyboard 10.

In addition, the keyboard 10 can preferably adopt a conductive post trigger design (but not limited to this). For example, as shown in Figure 2, the position of the thin film circuit board 16 corresponding to the elastic reset member 22 can have a conductive contact point 34, and the elastic reset member 22 extends downward toward the conductive contact point 34 to form a conductive actuating post 36 (such as a conductive carbon post, etc.). Therefore, when the key cap 18 is pressed, the elastic reset member 22 can bend and deform to drive the conductive actuating post 36 downward to contact the conductive contact point 34 to generate a corresponding key signal, so that the keyboard 10 can execute the function desired by the user. In addition, as shown in FIG. 2, the thin film circuit board 16 may be formed with an air escape hole 38 at the position corresponding to the elastic reset member 22, so that when the key cap 18 is pressed to cause the elastic reset member 22 to bend and deform, the air inside the elastic reset member 22 may be discharged to the outside of the elastic reset member 22 through the air escape hole 38, thereby preventing the elasticity of the elastic reset member 22 from being affected by air and reduced.

It is worth mentioning that the present invention can further adopt a backlight design. For example, please refer to Figures 2, 3 and 4. Figure 4 is a partially enlarged top perspective view of the light guide plate 42 in Figure 2. As shown in Figures 2, 3 and 4, at least one light-emitting diode 40 (two are shown in Figure 2, respectively located on both sides of the elastic reset member 22, but not limited thereto) is disposed at the position of the thin film circuit board 16 corresponding to the key body 12 to emit light to the key cap 18, thereby generating a key luminous effect. In practical applications, the keyboard 10 may further include a light guide plate 42 (the light guide plate 42 and the thin film circuit board 16 may constitute the backlight module 11 of the keyboard 10) disposed between the thin film circuit board 16 and the bottom plate 14. The position of the light guide plate 42 corresponding to the LED 40 may be formed with a slot 44 to accommodate the LED 44 and guide the light of the LED 44 to be incident on the key cap 18. The position of the bottom plate 14 corresponding to the LED 44 may preferably be formed with an avoidance hole 46 to accommodate the LED 44, so as to effectively avoid the problem of the LED 44 being damaged by pressure due to interference between the bottom plate 14 and the LED 44. A second through hole 48 may be formed at the position of the light guide plate 42 corresponding to the elastic reset member 22, so that the elastic reset member 22 can pass through the first through hole 24 and the second through hole 48 to be disposed on the thin film circuit board 16, wherein the second through hole 48 with a larger hole area can be connected to the slot 44 with a smaller hole area to preferably present a keyhole shape (but not limited to this shape).

In addition, in order to improve the light utilization efficiency of the light guide plate 42, the present invention can further adopt an optical microstructure design. For example, as shown in Figures 2 and 4, an optical microstructure 50 can be formed on the light guide plate 42 and preferably adopts a micro-prism structure design (but not limited to this, it can also adopt other optical scattering designs, such as metal paint/white paint design, concave-convex micro-dot structure design, continuous line microstructure design, etc.). Thereby, the optical microstructure 50 can guide the light from the light-emitting diode 44 incident on the light guide plate 42 to pass through the base plate 14 and be incident on the corresponding character position on the key cap 18, thereby producing a character luminous effect. Furthermore, in order to improve the uniformity of the light emission of the characters on the key cap 18, the present invention may adopt a design with different microstructure densities. For example, as shown in FIG. 4, the key cap 18 may have at least one middle character S1 and at least one side character S2 (in FIG. 4, one middle character S1 and four side characters S2 are shown in dashed boxes, but the number and position of the characters are not limited thereto). The microstructure density of the low beam region R1 of the optical microstructure 50 close to the LED 40 and corresponding to the side character S2 may be preferably smaller than that of the optical microstructure 50 far from the LED 40. The microstructure density of the far beam region R2 corresponding to the middle character S1 is greater than the microstructure density of the remaining regions of the optical microstructure 50 except the low beam region R1 and the far beam region R2. Thus, the light emitted by the LED 40 can be more evenly incident on the middle character S1 and the side characters S2 through the microstructure sparse and dense configuration as shown in FIG. 4, so as to avoid the problem that the brightness of the characters close to the LED 40 on the key cap 18 is too bright but the brightness of the characters far from the LED 40 is insufficient, thereby producing a uniform lighting effect of the brightness of the characters on the key cap 18.

In actual application, in order to further avoid the problem of over-bright characters and light leakage from keys and to improve the light utilization efficiency of the LED 40, the present invention can adopt an ink layer reflection and light shielding design. For example, please refer to Figures 2 and 5. Figure 5 is a schematic diagram of the ink layer configuration of the bottom plate 14 in Figure 2. In order to clearly show the configuration of the ink layer on the bottom plate 14, the bottom plate 14 is simply shown in a dotted frame in Figure 5. As shown in FIG. 2 and FIG. 5 , a ridge-shaped ink layer 52 (composed of opaque ink, such as black ink, but not limited to this) can be formed on the base plate 14 along the position of the projection outline P of each key body 12 on the base plate 14, and the reflective ink layer 54 can preferably be a white ink layer (but not limited to this, it can also be realized by using a paint with highly reflective particles, or even a metal layer or metal paint, wherein the reflective ink layer 54 needs to have a reflectivity of at least 15-20%, and the reflective ink layer 54 can also have a considerable transmittance or absorption rate at the same time) and is formed at the position of the base plate 14 corresponding to the LED 40 and is located above the LED 40. Through the above configuration, the ridge-shaped ink layer 52 can prevent the light penetrating the bottom plate 14 from being directly emitted to the outside of the key body 12 to produce an anti-light leakage effect. On the other hand, the reflective ink layer 54 can reflect at least part of the light emitted upward by the LED 40 back into the light guide plate 42 and incident on the optical microstructure 50 (as shown in Figure 2). In this way, the light in the light guide plate 42 can be scattered by the optical microstructure 50 through the bottom plate 14 and incident on the corresponding character position on the key cap 18 to produce a character luminous effect, thereby solving the problem mentioned in the prior art that the light emitted upward by the LED will directly incident on the key, causing the character to be too bright, thereby greatly improving the luminous uniformity of the keyboard 10 and the visual aesthetic effect when in use.

It should be noted that the configuration of the above-mentioned reflective ink layer and opaque ink layer can also be selectively applied to the light guide plate 42 and the thin film circuit board 16. For example, please refer to Figure 4 and Figure 6. Figure 6 is a schematic diagram of the ink layer configuration of the thin film circuit board 16 in Figure 2. In order to clearly show the configuration of the ink layer on the thin film circuit board 16, the thin film circuit board 16 is only briefly shown in a dotted frame in Figure 6. First, as shown in Figure 4, a ridge-shaped ink layer 56 (composed of opaque ink, such as black ink, but not limited to this) is formed on the light guide plate 42 along the position of the projection outline P of each key body 12 on the light guide plate 42 to prevent the light emitted from the light guide plate 42 from directly emitting to the outside of the key body 12 to produce an anti-light leakage effect. Furthermore, as shown in FIG. 6 , a reflective ink layer 58 (preferably a white ink layer, but not limited thereto) is formed on the thin film circuit board 16 at the position corresponding to each key body 12 to reflect the light emitted downward from the light guide plate 42 back to the light guide plate 42, and a ridge-shaped ink layer 60 (composed of opaque ink, such as black ink, but not limited thereto) is formed on the thin film circuit board 16 along the position of the projection outline P of each key body 12 on the thin film circuit board 16 to prevent light from penetrating the thin film circuit board 16, thereby further improving the light utilization efficiency of the light from the LED 40 incident on the light guide plate 42.

In addition, the present invention can further adopt a glue layer design. For example, please refer to Figure 7, which is a partially enlarged top perspective view of the glue layer configuration of the light guide plate 42 in Figure 2. It can be seen from Figure 7 that the backlight module 11 of the keyboard 10 can further include at least one annular glue layer 62 (two annular glue layers 60 are shown in Figure 7 to correspond to the two light-emitting diodes 40 respectively, but not limited to this). The annular glue layer 62 is arranged around the light-emitting diode 40 and can be attached to the lower surface of the light guide plate 42 (or between the light guide plate 42 and the thin film circuit board 16), or the annular glue layer 62 can also be arranged on the upper surface of the light guide plate 42 (or between the light guide plate 42 and the bottom plate 14). The annular adhesive layer 62 makes the LED 40 and the light guide plate 42 closely attached to each other and has a good light coupling effect. Through the design of the annular adhesive layer 62, the light of the LED 40 can directly or indirectly reach the medium on the other side of the annular adhesive layer 62, so that the light can be emitted from the light guide plate 42 and then reflected by the reflective ink layer 5. 4 and the reflective ink layer 58 to reflect back to the light guide plate 42 to prevent the light from escaping and being lost in the air gap between the light guide plate 42 and the base plate 14 or in another air gap between the light guide plate 42 and the thin film circuit board 16, so as to ensure that a sufficient proportion of light can continue to be transmitted horizontally in the light guide plate 42 to a farther position, thereby improving the luminous uniformity of the keyboard 10. In addition, as shown in FIG. 7, the backlight module 11 of the keyboard 10 may further include a fixed adhesive layer 64, which may be formed along the projection outline P of each key body 12 on the light guide plate 42 in a ridge-like shape and attached to the lower surface of the light guide plate 42 (or between the light guide plate 42 and the thin film circuit board 16), or the fixed adhesive layer 62 may also be disposed on the upper surface of the light guide plate 42 (or between the light guide plate 42 and the bottom plate 14), so as to improve the fixed fit between the light guide plate 42 and the bottom plate 14/thin film circuit board 16, thereby effectively preventing light from leaking from the air gap between the light guide plate 42 and the bottom plate 14/thin film circuit board 16 and improving the light coupling efficiency.

It is worth mentioning that the connection structure and plastic base plate integral molding design, conductive column trigger design, base plate avoidance hole design, base plate hook arm design, keyboard plastic material composition design, and light guide plate perforation/slot hole design mentioned in the above embodiments can be implemented separately or selectively combined and applied interactively, so as to enhance the design flexibility of the keyboard of the present invention. For example, the present invention can only adopt the connection structure and plastic base plate The one-piece design improves the keyboard's environmental protection and recyclability and is conducive to the keyboard's lightweight design. As for other derivative variation embodiments (for example, only the bottom plate hook arm design is used to improve the keyboard's assembly and disassembly convenience and environmental protection and recyclability, only the light guide plate perforation/slot design is used to accommodate the elastic reset member/light-emitting diode, etc.), the relevant descriptions can be deduced from this, and will not be repeated here.

The above is only the preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope of the present invention.

10: Keyboard

11: Backlight module

12: Button body

14: Base plate

16: Thin film circuit board

18: Key caps

20: Lifting mechanism

22: Elastic return member

24: First piercing

26: Connection structure

28: Hook arm

30: Loading base

31: snap-fit hole structure

34: Conductive contact point

36: Conductive actuator column

38: Escape hole

40: LED

42: Light guide plate

44: Slot

46: Avoidance hole

48: Second piercing

50:Optical microstructures

52, 56, 60: Ridge-shaped ink layer

54, 58: Reflective ink layer

D1: Fastening direction

D2: Disassembly direction

Claims (17)

A backlight module is used to provide light to a plurality of key bodies of the keyboard. Each key body has a key cap and an elastic reset member. The key cap has at least one middle character and at least one side character. The elastic reset member abuts against the key cap. The backlight module includes: a thin film circuit board, at least one light-emitting diode is arranged at a position corresponding to the key body. The at least one light-emitting diode is located on at least one side of the elastic reset member and emits light to the key cap; and a light guide plate is arranged on the thin film circuit board. The light guide plate has at least one slot to accommodate the at least one light-emitting diode. And having a perforation corresponding to the elastic reset member, an optical microstructure is formed on the light guide plate to guide the light of the at least one LED to be incident on the key cap, the microstructure density of a low beam area of the optical microstructure close to the at least one LED and corresponding to the at least one side character is less than the microstructure density of a high beam area of the optical microstructure far from the at least one LED and corresponding to the at least one middle character, but greater than the microstructure density of the remaining areas of the optical microstructure except the low beam area and the high beam area, and the elastic reset member passes through the perforation to be arranged on the thin film circuit board. The backlight module as described in claim 1, wherein the through hole is connected to the at least one slot to form a keyhole shape. As described in claim 1, a backlight module is formed on the light guide plate along the position of a projection outline of each key body on the light guide plate, and a ridge-shaped ink layer is formed, and the ridge-shaped ink layer is composed of opaque ink. The backlight module as described in claim 1, wherein the thin film circuit board is coated with a reflective ink layer at the position corresponding to each key body. As described in claim 1, a backlight module is formed on the thin film circuit board along the position of a projection outline of each key body on the thin film circuit board, and the ridge-shaped ink layer is composed of opaque ink. The backlight module as described in claim 1 further comprises: at least one annular adhesive layer, which is attached between the light guide plate and the thin film circuit board and is arranged around the at least one light-emitting diode. The backlight module as described in claim 1 further comprises: a fixed adhesive layer, which is formed along a projection outline of each key body on the light guide plate and is shaped like a ridge and is attached between the light guide plate and the thin film circuit board. A keyboard comprises: a plurality of key bodies, each of which has a key cap, a lifting mechanism, and an elastic reset member, the lifting mechanism being movably connected to the key cap, the key cap having at least one middle character and at least one side character, the elastic reset member abutting against the key cap; a light-transmitting bottom plate having a first through hole formed at a position corresponding to each elastic reset member , each lifting mechanism can be movably connected to the transparent bottom plate so that each key cap can move up and down relative to the transparent bottom plate; a thin film circuit board, which is arranged under the transparent bottom plate and has at least one light-emitting diode arranged at a position corresponding to the key body, and the at least one light-emitting diode is located on at least one side of the elastic reset member and emits light to the key cap; and a light guide plate, It is arranged between the thin film circuit board and the transparent bottom plate. The light guide plate has a slot for accommodating the at least one light emitting diode and a second perforation corresponding to the elastic reset member. An optical microstructure is formed on the light guide plate to guide the at least one light emitting diode to be incident on the key cap. The microstructure density of a low beam area of the optical microstructure close to the at least one light emitting diode and corresponding to the at least one side character is less than the microstructure density of a high beam area of the optical microstructure far from the at least one light emitting diode and corresponding to the at least one middle character, but greater than the microstructure density of the remaining areas of the optical microstructure except the low beam area and the high beam area. The elastic reset member passes through the first perforation and the second perforation to be arranged on the thin film circuit board. A keyboard as described in claim 8, wherein the second through hole is connected to the slot to form a keyhole shape. A keyboard as described in claim 8, wherein a ridge-shaped ink layer is formed on the light guide plate around the position of a projection outline of each key body on the light guide plate, and the ridge-shaped ink layer is composed of opaque ink. A keyboard as described in claim 8, wherein the thin film circuit board is coated with a reflective ink layer corresponding to the position of each key body. A keyboard as described in claim 8, wherein a ridge-shaped ink layer is formed on the thin film circuit board around the position of a projection outline of each key body on the thin film circuit board, and the ridge-shaped ink layer is composed of opaque ink. The keyboard as described in claim 8, wherein the backlight module further comprises: At least one annular adhesive layer, which is attached between the light guide plate and the thin film circuit board and is arranged around the at least one light-emitting diode. The keyboard as described in claim 8, wherein the backlight module further comprises: a fixed adhesive layer, which is formed along a projection contour of each key body on the light guide plate and is formed in a ridge shape and is attached between the light guide plate and the thin film circuit board. A keyboard as described in claim 8, wherein a ridge-shaped ink layer is formed on the transparent base plate around the position of a projection outline of each key body on the transparent base plate, and the ridge-shaped ink layer is composed of opaque ink. A keyboard as described in claim 8, wherein the transparent bottom plate is formed with a avoidance hole at a position corresponding to the at least one LED to accommodate the at least one LED. A keyboard as described in claim 8, wherein the light-transmitting bottom plate is formed with a plurality of hook arms and a plurality of connection structures in an integral manner, wherein the connection structure can be movably connected to the lifting mechanism, so that the key cap can move up and down relative to the light-transmitting bottom plate to trigger the thin film circuit board; the plurality of hook arms pass through the thin film circuit board to be respectively snapped onto a plurality of snap hole structures of a supporting base of a computer device, so that the keyboard can be detachably mounted on the computer device.

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