TWI851171B - Backlight keyswitch and backlight module thereof - Google Patents

Abstract

A backlight keyswitch includes a keycap, a base plate, a membrane circuit board and a backlight module. The base plate is disposed underneath the keycap. The membrane circuit board is disposed in parallel to the keycap and the base plate. The backlight module is disposed under the base plate, which includes a shielding sheet, a light guide panel, a lighting board and a protrusion structure. The shielding sheet includes a light-permeable area corresponding to the keycap. The light guide panel is disposed under the shielding sheet. The lighting board is disposed under the light guide panel and includes a light source. The protrusion structure protrudes toward the light source and is formed on one of the base plate, the membrane circuit board and the shielding sheet. The protrusion structure reflects at least partial light of the light source to enter the light guide panel for lateral transmission.

Description

Backlit keys and backlight modules

The present invention relates to a backlight key and its backlight module, in particular to a backlight key and its backlight module having a protruding structure protruding toward a light source, so that more light from the light source enters the light guide plate for horizontal transmission.

With the development of technology, keyboard designs are becoming more and more diverse. When users choose a keyboard, in addition to the basic input function, the keyboard's visual effect is also important to users. Currently, luminous keyboards are available on the market. In addition to the need for nighttime or low-light environments, they can also provide visual feedback to users. When a luminous keyboard uses a low-brightness LED to illuminate each square key, the following problems will occur: (1) the main symbol above the LED is too bright, while the corner symbol of the keycap is too dark; (2) the brightness of the halo at the edge of the keycap is inconsistent; and (3) the overall illumination of a single key and multiple keys is inconsistent.

According to one embodiment, the backlight key provided by the present invention includes a key cap, a base plate, a thin film circuit board and a backlight module. The base plate is located below the key cap; the thin film circuit board is arranged parallel to the key cap and the base plate. The backlight module is arranged under the base plate, and includes a shading sheet, a light guide plate, a light board and a protruding structure. The shading sheet has a light-transmitting area corresponding to the key cap; the light guide plate is arranged under the shading sheet; the light board is arranged under the light guide plate and has a light source. The protruding structure protrudes toward the light source, and it is formed on one of the base plate, the thin film circuit board and the shading sheet, and the protruding structure reflects at least part of the light of the light source to enter the light guide plate for horizontal transmission. In one embodiment, the backlight module further includes a first reflective layer formed on the lamp plate, and the first reflective layer at least partially overlaps with the protruding structure in the vertical direction. In one embodiment, the light guide plate has a light guide hole to accommodate the light source, and the first reflective layer at least partially overlaps with the light guide hole in the vertical direction. In one embodiment, the backlight module further includes a second reflective layer formed on the light shielding sheet, and the second reflective layer at least partially overlaps with the protruding structure in the vertical direction. In one embodiment, the bottom plate has a plurality of through holes surrounding the protruding structure in the vertical direction. In one embodiment, the protruding structure is located on the bottom plate, and the light shielding sheet has an avoidance hole to accommodate the protruding structure. In one embodiment, the protruding structure is located on the thin film circuit board, and the bottom plate has a through hole to accommodate the protruding structure.

According to another embodiment, the backlight module provided by the present invention is used to illuminate at least one keycap, and includes a shading sheet, a light guide plate, a lamp board and a protruding structure. The shading sheet has a light-transmitting area; the light guide plate is disposed under the shading sheet; the lamp board is disposed under the light guide plate and has a light source. The protruding structure is formed on the shading sheet and protrudes toward the light source, and the protruding structure reflects at least part of the light from the light source to enter the light guide plate for horizontal transmission. In one embodiment, the backlight module further includes a first reflective layer formed on the lamp board, and the first reflective layer at least partially overlaps with the protruding structure in the vertical direction. In one embodiment, the light guide plate has a light guide hole to accommodate the light source, and the first reflective layer at least partially overlaps with the light guide hole in the vertical direction. In one embodiment, the backlight module further includes an internal reflection area formed on the light shielding sheet, and the internal reflection area at least partially overlaps with the protruding structure in the vertical direction. In one embodiment, the light guide plate has a light guide hole to accommodate the light source, and the internal reflection area at least partially overlaps with the light guide hole in the vertical direction. In one embodiment, the backlight module further includes an inner mask area formed above the inner reflection area, and the inner mask area overlaps with the protruding structure in the vertical direction. In one embodiment, the light guide plate has a light guide hole corresponding to the protruding structure, and the light source is arranged in the light guide hole. In one embodiment, the backlight module further includes a glue layer at least partially surrounding the protruding structure in the vertical direction. In one embodiment, the light guide plate has a light guide hole, and a non-glue area is provided between the at least one glue layer and the light guide hole of the light guide plate. In one embodiment, the backlight module further comprises a supporting frame disposed between the light plate and the light guide plate, the supporting frame is formed with a bottom hole to accommodate the light source, and a limit space is formed above the bottom hole to accommodate the light guide plate. In one embodiment, the backlight module further comprises a microstructure layer formed on the light guide plate or the light plate. In one embodiment, the protruding structure comprises an upper convex portion and a lower convex portion, wherein the lower convex portion protrudes toward the light source, and the upper convex portion protrudes away from the light source. In one embodiment, the upper convex portion surrounds the outer side of the lower convex portion. In one embodiment, the protruding structure further includes a side arc portion surrounding the outer side of the convex portion.

According to another embodiment, the backlight key provided by the present invention includes a key cap, a base plate, a thin film circuit board and a backlight module. The base plate is located below the key cap; the thin film circuit board is arranged parallel to the key cap and the base plate. The backlight module is arranged under the base plate, and includes a shading sheet, a light guide plate, a light board, a microstructure layer and a protruding structure. The shading sheet has a light-transmitting area; the light guide plate is arranged under the shading sheet; the light board is arranged under the light guide plate and has a light source. The microstructure layer includes a plurality of microstructures corresponding to the light-transmitting area of the shading sheet, and the microstructure layer also defines a microstructure clear area surrounding the light source, and the plurality of microstructures surround the microstructure clear area. The protruding structure is formed on the shading sheet and protrudes toward the light source, the protruding structure overlaps with the microstructure clear area, and the protruding structure reflects at least part of the light from the light source to enter the light guide plate for lateral transmission. In one embodiment, the bottom plate has a plurality of light-transmissive through holes corresponding to the light-transmissive areas of the shading sheet. In one embodiment, the plurality of through holes respectively have an inner portion, and the plurality of inner portions at least partially overlap with the microstructure clear area. In one embodiment, the backlight module further includes a glue layer located between the protruding structure and the plurality of inner portions. In one embodiment, the backlight module further includes a glue layer, and the microstructure clear area is at least partially located between the glue layer and the plurality of microstructures. In one embodiment, the backlight module further includes an internal reflection area formed on the light shielding film at a position corresponding to the light source, and the microstructure clear area is at least partially located between the internal reflection area and the plurality of microstructures.

In summary, the present invention can reflect and diffuse the light from the light source at the initial stage of the light path by setting a protruding structure on the backlight module to protrude toward the light source, so as to open the light transmission angle, increase the lateral transmission component, and increase the amount of light entering the light guide plate. In this way, the problems of the main characters above the light source being too bright, the sub-characters at the edge or corner of the keycap being too dark, the keycap outline halo brightness being inconsistent, and the overall illumination of single keys and multiple keys being inconsistent in the prior art are solved, thereby greatly improving the illumination uniformity and visual aesthetics of the backlit keys and backlit keyboards.

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, 100, 150, 200, 250: Backlit buttons

12: Keyboard

14: Base plate

15:Through hole

15a: Inner part

16: Thin film circuit board

18, 102, 152, 202, 252: Backlight module

20: Keycaps

22: Lifting mechanism

24: Reset piece

26, 206: Shading film

27: Translucent area

28, 154: Light guide plate

29, 155: Light guide hole

30: Light board

32, 104, 204: protruding structure

32a: convex part

32b: convex part

32c: Side arc part

34: Light source

36, 36’: Microstructure layer

37: Microstructure clear area

38, 106: Second reflection layer

38a: Internal reflection area

38b: External reflection area

38c: Rib reflexology area

40, 108: Mask layer

40a: Inner mask area

40b: Outer mask area

40c: Rib mask area

42: First reflective layer

44: Adhesive layer

45: No glue area

156:Carrying frame

158: Bottom frame

160: Limit frame

162: Bottom hole

164: Limited space

207: Avoidance hole

S1, S3: upper surface

S2: Lower surface

LKB: Backlit keyboard

Figure 1 is a simplified cross-sectional view of a backlight key according to one embodiment of the present invention.

Figure 2 is a simplified exploded view of the base plate, shading sheet, light guide plate, and light panel in Figure 1.

Figure 3 is a diagram of different ink layer configurations proposed according to different embodiments of the present invention.

Figure 4 is a simplified cross-sectional view of a backlight key according to another embodiment of the present invention.

Figure 5 is a simplified cross-sectional view of a backlight key according to another embodiment of the present invention.

Figure 6 is a simplified exploded view of the base plate, light shielding plate, light guide plate, support frame and light board in Figure 5.

Figure 7 is a simplified cross-sectional view of a backlight key according to another embodiment of the present invention.

Figure 8 is a simplified cross-sectional view of a backlight key according to another embodiment of the present invention.

Figure 9 is a top perspective view of the configuration of the key cap, base plate, light source and microstructure layer according to another embodiment of the present invention.

Figure 10 is a schematic diagram of a stacked backlight keyboard applicable to the embodiment of the present invention.

Figure 11 is a schematic partial cross-sectional view of a backlight module of another embodiment of the present invention.

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 various 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 proportions and configurations of the various components in the drawings (such as the size of the through holes, the proportions of the ink layers, etc.) are only for exemplary purposes and do not represent the actual implementation of the present invention. The components mentioned in the following embodiments or general descriptions of the present invention have the same name and/or the same number, which represent the same or similar structures and functions, and will not be repeated.

Each embodiment of the present invention aims to increase the proportion of lateral transmission of the light source, that is, to reduce the light output of the main characters on the keycaps corresponding to the surrounding area directly above the light source, and to increase the light output of the characters on the sides or corners of the keycaps. Low-power light sources such as mini LEDs or micro LEDs are used in low-travel keys with a short vertical light output distance (1-2mm), and a large target light output area (covering the main character/sub-character/keycap edge halo) (about 10-12mm). If the number and power of light sources are not increased, pure optical means must be used to prevent light from escaping. However, in a small space, how to allow 80% of the light sources that emit light upward to open the light transmission angle so that most of the light enters the light guide plate for lateral transmission is a major problem. Another problem is that if the light is allowed to diffuse through multiple reflections around the light source before the light transmission direction/angle is smoothly converted to lateral transmission inside the light guide plate (for example, reaching the critical angle of total reflection), the light will be wasted unnecessarily at the beginning of the light source. Therefore, reducing the initial loss is another difficult problem.

Please refer to FIG. 1 and FIG. 2. FIG. 1 is a cross-sectional schematic diagram of a backlight keypad 10 according to an embodiment of the present invention. FIG. 2 is an exploded schematic diagram of the bottom plate 14, the light shielding sheet 26, the light guide plate 28, and the light board 30 of FIG. 1. FIG. 10 is a stacked schematic diagram of the backlight keyboard 10 applicable to the embodiment of the present invention. The backlight keypad 10 can be preferably applied to general electronic devices, such as a backlight keyboard LKB of a notebook computer or an independent keyboard device, but is not limited thereto. The backlight keypad 10 provides a character illuminating function so that the user can recognize and press to input text, numbers, symbols or perform other functions. As shown in FIG. 1 and FIG. 2, the backlight key 10 includes a key body 12, a bottom plate 14, a thin film circuit board 16, and a backlight module 18. As shown in FIG. 1, the key body 12 may include a key cap 20, a lifting mechanism 22, and a reset member 24. The bottom plate 14 is disposed under the key body 12 and the key cap 20, and is connected to the key body 12 and the key cap 20 so that the key body 12 and the key cap 20 can move up and down relative to the bottom plate 14. The bottom plate 14 has one or more through holes 15 at the position corresponding to the key body 12. When the bottom plate 14 is opaque (such as made of metal or opaque material), the through holes 15 allow light from the backlight module 18 to pass through and illuminate the key 20. The thin film circuit board 16 is arranged parallel to the key cap 20 and the bottom plate 14, for example, between the key body 12 and the bottom plate 14, or below the bottom plate 14. The thin film circuit board 16 has a key circuit connected to a plurality of switches, which correspond to each backlight key 10 respectively, and can generate corresponding key signals when triggered. The lifting mechanism 22 is connected between the key cap 20 and the bottom plate 14, and the lifting mechanism 22 can rotate and/or move to support the key cap 20 to move up and down. The reset member 24 is elastic and can provide a restoring force to support the key cap 20 to return to the initial position when under pressure. The key body 12 also includes a triggering portion disposed on the lower surface of one of the key cap 20, the reset member 24 or the lifting mechanism 22, which can trigger the switch of the thin film circuit board 16 as the key cap 20 moves up and down, thereby generating a key signal.

In detail, the backlight module 18 is disposed below the key body 12, the key cap 20 and the bottom plate 14, and includes a light shielding sheet 26, a light guide plate 28, a lamp plate 30, and a protruding structure 32. In a broad sense, the backlight module 18 can also include the bottom plate 14 and the thin film circuit board 16, because in theory these multi-layer stacking structures can integrate circuits and components to reduce the total number of layers. To ensure that the light escaping from the light guide plate 28 can be recovered to the light guide plate 28 for continued transmission, the lamp plate 30 and the light shielding sheet 26 have a first reflective layer 42 and a second reflective layer 38 on the upper and lower surfaces facing the light guide plate 28, respectively.

The shading sheet 26 is disposed between the bottom plate 14 and the light guide plate 28. For example, the shading sheet 26 may be provided with the aforementioned second reflective layer 38 on a transparent substrate to reduce and/or prevent light from passing through a specific portion. At the light-emitting position corresponding to the key body 12 (such as characters and halo), the shading sheet 26 is not provided with the second reflective layer 38 so as to form a light-transmitting area 27. The second reflective layer 38 may be a white ink or paint layer, or may be implemented by a paint with highly reflective particles, or even a metal layer or metal paint. The second reflective layer 38 generally has a reflectivity of at least 15-20%. If necessary, the second reflective layer 38 may also have a considerable transmittance to allow local light to pass through. The second reflective layer 38 may include an inner reflective area 38a (block-shaped), an outer reflective area 38b (frame-shaped), and a rib reflective area 38c (if necessary). The light-transmitting area 27 surrounds the inner reflection area 38a, and the outer reflection area 38b surrounds the light-transmitting area 27, so that the light-transmitting area 27 surrounds the inner reflection area 38a and the outer reflection area 38b. The outer reflection area 38b corresponds to the inner and outer peripheral areas of the key cap 20, so as to prevent the user from seeing the highlights (such as the microstructures described later) below the through hole 15 of the bottom plate 14 through the gaps around the key cap 20. The rib reflection area 38c is disposed between the inner reflection area 38a and the outer reflection area 38b, and each is spaced a distance apart. The inner reflection area 38a corresponds to and covers the light source 34. This is to allow the strongest light to be reflected into the light guide plate 28, avoid the problem of the main characters of the key cap 20 being too bright, help improve the brightness of the edge or corner characters, and also help improve the luminous uniformity of the backlit key 10. If necessary, the light shielding sheet 26 may include a mask layer 40 to further shield the light penetrating the second reflection layer 38. The mask layer 40 may be a black ink layer or a metal paint layer, and is formed above the second reflection layer 38 corresponding to the position of the light source 34. The mask layer 40 can be divided into an inner mask area 40a, an outer mask area 40b, and a rib mask area 40c.

The light guide plate 28 is located below the light shielding sheet 26, and the lamp plate 30 is disposed below the light guide plate 28 and has a light source 34. The light guide plate 28 has a light guide hole 29 at a position corresponding to the key body 12/key cap 20/light source 34, and the light source 34 is disposed in the light guide hole 29. The light source 34 includes one or more light-emitting bodies (for example, light-emitting diode grains of different colors, but not limited to this). The backlight module 18 further includes a microstructure layer 36, and the microstructure layer 36 can be disposed parallel to the light guide plate 28 and the lamp plate 30. The microstructure layer 36 is disposed correspondingly in the area below the main character/sub-character of the key cap 20, such as formed on the upper surface or lower surface of the light guide plate 28, or formed on the upper surface of the reflective layer of the lamp plate 30, or independently formed between the light guide plate 28 and the lamp plate 30. The microstructure layer 36 is a diffusion structure, such as metal paint/white paint microdots, concave-convex microdot structures, linear concave-convex structures composed of line segments or continuous lines, etc.

The protruding structure 32 can be formed on the light shielding sheet 26 and above the light source 34. The main purpose of providing the protruding structure 32 is to diffuse the light and open or increase the light transmission angle (relative to the top normal of the light source 34), that is, to allow the light to have a larger lateral transmission component, so that more light can enter the light guide plate 28 at the beginning of light emission and be transmitted laterally in the light guide plate 28 through total reflection. In general, the protruding structure 32 of the present invention can be disposed on any element above the light source 34, such as the shading sheet 26 (Figs. 1 and 5), the bottom plate 14 (Figs. 7 and 8), or the thin film circuit board 16 (Fig. 4); the protruding structure 32 can be integrally formed by the shading sheet 26, the bottom plate 14, or the thin film circuit board 16 (for example, by stamping with a mold), or fixed as an independent element on the surface of the shading sheet 26, the bottom plate 14, or the thin film circuit board 16 (for example, by printing or dotting paint, ink, or glue to form bumps). The height of the protruding structure 32 can be, for example, 18% to 95% of the thickness of the light guide plate 28.

It is contrary to common sense that the protruding structure 32 protrudes toward the light source 34. When a low-power light source such as mini LED or micro LED is used, the height of the light source 34 is significantly lower than that of a traditional LED, and the backlight module 18 and its shading sheet 26, light guide plate 28 and lamp board 30 have all undergone a process of thinning. The protruding structure 32 protruding toward the light source 34 may cause the backlight module 18 to be too thick at the light source 34, causing the top or bottom surface of the backlight module 18 to bulge. The downward bulge of the backlight module 18 is that the lamp board 30 protrudes downward at the light source 34, which causes the wiring of the lamp board 30 to be partially bent near the light source 34, making it possible for the welding point of the light source 34 to peel off. Alternatively, the shading sheet 26 may also bulge upward at the light source 34. Regardless of whether the backlight module 18 is convex or concave at the light source 34, the light source 34 may interfere with the protruding structure 32, thereby damaging the surface fluorescent body of the light source 34, and ultimately causing color deviation problems (for example, white light is blue or multi-color mixed light has color deviation). The third problem is that if the protruding structure 32 partially enters the light guide hole 29 of the light guide plate 28, it will force the light source 34 to move downward relative to the light source 34, affecting the optical coupling mechanism between the light source 34 and the hole wall of the light guide hole 29. The fourth problem is that if the light guide hole 29 of the light guide plate 28 cannot completely accommodate the protruding structure 32, the outer area of the protruding structure 32 may cause unnecessary air gaps, resulting in light dissipation loss. However, on the contrary, solving these problems also means that the present invention protrudes the protruding structure 32 toward the light source 34, which can be transformed into a favorable solution.

In FIG. 1 , the protruding structure 32 is formed by the transparent substrate of the light shielding sheet 26 protruding downward, or by forming a transparent or non-transparent protrusion at the same place. The inner reflection area 38a and the inner mask area 40a of the light shielding sheet 26 can be overlapped and formed on the upper surface S1 or the lower surface S2 of the protruding structure 32. In addition, the stacking configuration of the ink layer is not limited to the above-mentioned embodiment, which means that the present invention can also adopt other ink layer stacking designs, and the ink layer size ratio and ink color and type are changed depending on the actual light output application of the backlight module 18. For example, please refer to FIG. 3, which is a different ink layer configuration diagram proposed according to different embodiments of the present invention. As shown in FIG. 3 (a), the second reflective layer 38 (inner reflection area 38a) can be formed on the lower surface S2 of the protruding structure 32, and the mask layer 40 (inner mask area 40a) can be formed between the second reflective layer 38 (inner reflection area 38a) and the lower surface S2 of the protruding structure 32; as shown in FIG. 3 (b), the second reflective layer 38 (inner reflection area 38a) can be formed on the lower surface S2 of the protruding structure 32, and the mask layer 40 (inner mask area 40a) can be formed on the upper surface S1 of the protruding structure 32. The diffusion effect of the protruding structure 32 can come from the second reflective layer 38 (internal reflection area 38a) or the protruding structure 32 itself; the smooth or rough curved surface of the protruding structure 32, or the protruding structure 32 is made of reflective material, so that the protruding structure 32 can provide the effect of diffusing light without the help of the second reflective layer 38 (internal reflection area 38a). The protruding structure 32 can have a single or multiple protrusions, or form multiple concave and convex areas, and is set in a close distance within the light emitting range of the light source 34, such as an elliptical hemisphere with a horizontal angle of 360 degrees and a vertical angle of 120 degrees.

In addition, the present invention can further adopt a glue layer design. For example, as shown in FIG. 1, the backlight module 18 can further include at least one glue layer 44. FIG. 1 shows a glue layer 44 attached between the light shielding sheet 26 and the light guide plate 28. The glue layer 44 at least partially surrounds the protruding structure 32, the light guide hole 29 and the light source 34. FIG. 1 also shows another glue layer 44 attached between the light guide plate 28 and the first reflective layer 42. The glue layer 44 also at least partially surrounds the protruding structure 32, the light guide hole 29 and the light source 34. The aforementioned glue layer 44 is arranged parallel to the light shielding sheet 26, the light guide plate 28, and the light panel 30. A non-glue area 45 is preferably provided between the glue layer 44 and the light guide hole 29 of the light guide plate 28 to prevent the glue layer 44 from entering the light guide hole 29 of the light guide plate 28 and adhering to the light source 34 during the manufacturing process, resulting in excessive light emission or the light source 34 falling off. The non-glue area 45 can be provided on the upper surface of the light guide plate 28 (or between the light guide plate 28 and the light shielding sheet 26), or the non-glue area 45 can be provided on the lower surface of the light guide plate 28 (or between the light guide plate 28 and the light board 30). The adhesive layer 44 has a good light coupling effect. Through the design of the above-mentioned adhesive layer 44, the light from the light source 34 can smoothly reach the medium on the other side of the adhesive layer 44 when it is directly or indirectly incident on the adhesive layer 44, so that the light can be reflected back to the light guide plate 28 between the second reflective layer 38 and the first reflective layer 42 after emitting from the light guide plate 28, so as to avoid the light from being lost in the air gap between the light guide plate 28 and the light shielding sheet 26, or in another air gap between the light guide plate 28 and the lamp panel 30 and the first reflective layer 42, so as to ensure that a sufficient proportion of light can continue to be transmitted horizontally in the light guide plate 28 to a farther position.

Through the above configuration, the protruding structure 32 can diffuse the light and open or increase the light transmission angle (relative to the top normal of the light source 34), increase the lateral transmission component of the light, and allow more light to enter the light guide plate 28 for lateral transmission at the initial stage of light emission. Then, through the optical coupling effect of the glue layer 44 surrounding the protruding structure 32, the initial scattered light can be guided back to the light guide plate 28. In addition, the light scattered from the upper and lower surfaces of the light guide plate 28 can be reflected and recovered to the light guide plate 28 through the first reflection layer 42 and the second reflection layer 38, ensuring that as much light as possible reaches the side and corner of the key cap 20. At this time, the light can be diffused upward through the microstructure layer 36 (as shown in Figure 1) to allow the light to pass through the light guide plate 28 upward. In this way, the light can continue to pass through the light-transmitting area 27 of the light-shielding sheet 26, the through hole 15 of the bottom plate 14 and the thin film circuit board 16 in sequence and emit light from the key cap 20, thereby producing the luminous characters of the key cap 20 and the surrounding halo effect, and achieving a considerable degree of uniformity.

In summary, the present invention adopts the arrangement of overlapping the protruding structure and the light source, and the light from the light source can be reflected and diffused at the initial stage of the light path by the protruding structure protruding toward the light source, so as to open the light transmission angle, increase the lateral transmission component, and increase the amount of light entering the light guide plate 28. In this way, in addition to preventing the middle characters from being too bright, the brightness of the side or corner characters is also increased, thereby greatly improving the uniformity of the backlight keys and the visual aesthetics when in use.

It is worth mentioning that the formation position of the protruding structure is not limited to the above-mentioned embodiment. For example, please refer to FIG. 4, which is a cross-sectional diagram of a backlight key 100 according to another embodiment of the present invention. As shown in FIG. 4, the backlight key 100 includes a key body 12, a bottom plate 14, a thin film circuit board 16 and a backlight module 102. The backlight module 102 may include a light shielding sheet 26, a light guide plate 28, a light board 30, and a protruding structure 104. In this embodiment, the protruding structure 104 can be formed on the thin film circuit board 16, protruding toward the light source 34, so as to reflect and diffuse the light from the light source 34 at the initial stage of the light path, so as to open the light transmission angle, increase the lateral transmission component, and increase the amount of light entering the light guide plate 28, thereby achieving the aforementioned uniformity and aesthetic effect.

The light reflection and diffusion effect of the protruding structure 104 can occur at a position far from the light source 34. In this embodiment, the backlight module 102 can further include a second reflection layer 106 (similar to the internal reflection area 38a in FIG. 1) formed on the thin film circuit board 16 and corresponding to the light source 34. The second reflection layer 106 can preferably be a white ink layer. More specifically, as shown in FIG. 4, the second reflection layer 106 can be formed on the upper surface S3 of the protruding structure 104. In actual application, in order to prevent the light from partially penetrating the second reflective layer 106 and directly incident upward to the key body 12, the backlight module 102 may further include a mask layer 108. The mask layer 108 may preferably be a black ink layer or a metal paint layer, formed on the second reflective layer 106 at a position corresponding to the light source 34, so as to reduce or prevent the light penetrating the second reflective layer 106 from directly incident on the main characters of the key cap 20, thereby further improving the problem of the main characters being too bright. As for other related descriptions of this embodiment (such as the configuration of the reflective ink layer and the mask layer, the design of the glue layer, etc.), it can be referred to the above embodiment by analogy, and will not be repeated here.

In addition, the stacking configuration of the light guide plate and the lamp panel can also be arranged in other ways to accommodate the protruding structure, avoid excessive protrusion of the protruding structure, and affect the overall flatness of the backlight module 18 and the strength of the lamp panel; on the other hand, the interference between the protruding structure and the light source can be reduced to avoid affecting the light source fixing effect or damaging the fluorescent body. Please refer to Figure 5 and Figure 6. Figure 5 is a cross-sectional schematic diagram of a backlight key 150 proposed according to another embodiment of the present invention, and Figure 6 is an exploded schematic diagram of the bottom plate 14, the light shielding sheet 26, the light guide plate 154, the supporting frame 156 and the lamp panel 30 of Figure 5. The backlight key 150 includes a key body 12, a bottom plate 14, a thin film circuit board 16 and a backlight module 152. The backlight module 152 may include a light shielding sheet 26, a lamp panel 30, a protruding structure 32, a light guide plate 154 and a supporting frame 156. The light guide plate 154 may have a light guide hole 155 corresponding to the protruding structure 32. The supporting frame 156 is disposed between the lamp panel 30 and the light guide plate 154. The supporting frame 156 is formed with a bottom hole 162 to accommodate the light source 34. A limited space 164 is formed above the bottom hole 162 to position the light guide plate 154 at a relatively high position above the light source 34. The supporting frame 156 can be preferably formed by stacking a bottom frame 158 with a bottom hole 162 and a limiting frame 160 with a limited space 164 (but not limited thereto). If it is further applied to a backlight keyboard, the bottom frame 158 can adopt a grid structure design capable of forming multiple bottom holes 162 to respectively accommodate multiple light sources 34 on the light board 30, and the limiting frame 160 can adopt an outer ring sheet design and be stacked on the bottom frame 158 to form a limited space 164 to accommodate the entire light guide plate 154.

Through the above configuration, the protruding structure 32 can maintain a safer distance from the light source 34, avoiding problems caused by interference between the protruding structure 32 and the light source 34. At the same time, the height of the light source 34 is greatly reduced, so that the top surface of the light source 34 with a higher light output ratio is lowered from being close to the bottom surface of the light shielding sheet 26 or close to the top surface of the light guide plate 28 (see Figure 1) to being close to the bottom surface of the light guide plate 28 in Figure 5. In this way, the larger distance between the protruding structure 32 and the light source 34 can give the light a chance to open the transmission angle and increase the lateral transmission component; ultimately, it contributes to the uniformity and aesthetic effect of the main character/sub-character luminescence and the surrounding halo of the key cap 20. As for other related descriptions of this embodiment (such as the formation position of the protruding structure, the configuration of the reflective ink layer and the mask layer, the design of the glue layer, etc.), they can be deduced by analogy with the above-mentioned embodiments and will not be elaborated here.

In practice, the present invention can also form the protruding structure directly on the bottom plate, and can also keep a safe distance between the protruding structure and the light source. For example, please refer to Figure 7, which is a cross-sectional schematic diagram of a backlight key 200 proposed according to another embodiment of the present invention. As shown in Figure 7, the backlight key 200 includes a key body 12, a bottom plate 14, a thin film circuit board 16 and a backlight module 202. The backlight module 202 may include a light guide plate 28, a light board 30, a protruding structure 204, and a light shielding sheet 206. In this embodiment, the protruding structure 204 can be formed on the bottom plate 14 (preferably formed by a downward stamping embossing method, but not limited thereto) and protrude toward the light source 34. The light shielding sheet 206 may have a light-transmitting area 27 and a avoidance hole 207 is formed corresponding to the concave structure 204. Through the above configuration, the protruding structure 204 of the bottom plate 14 can maintain a safe distance from the light source 34, avoiding problems caused by interference between the protruding structure 32 and the light source 34. At the same time, the height of the light source 34 is greatly reduced, so that the top surface of the light source 34 with a higher light output ratio is lowered from being close to the bottom surface of the light shielding sheet 26 or close to the top surface of the light guide plate 28 (see Figure 1) to being between the top and bottom surfaces of the light guide plate 28 in Figure 7. In this way, the larger distance between the protruding structure 204 and the light source 34 can give the light an opportunity to open the transmission angle and increase the lateral transmission component; ultimately, it contributes to the uniformity and aesthetic effect of the light emission of the key cap 20 characters and the surrounding halo. As for other related descriptions of this embodiment (such as the configuration of the reflective ink layer and the mask layer, the design of the glue layer, etc.), they can be deduced by analogy with the above embodiments and will not be elaborated here.

In addition, the supporting frame design of the embodiment of Figure 5 can also be applied to the embodiment in which the base plate has a protruding structure. For example, please refer to Figure 8, which is a cross-sectional schematic diagram of a backlight key 250 proposed according to another embodiment of the present invention. As shown in FIG. 8 , the backlight key 250 includes a key body 12, a bottom plate 14, a thin film circuit board 16, and a backlight module 252. The backlight module 252 may include a lamp panel 30, a light guide plate 154, a support frame 156, a protruding structure 204, and a light shielding sheet 206. The support frame 156 is disposed between the lamp panel 30 and the light guide plate 154. The support frame 156 is formed with a bottom hole 162 to accommodate the light source 34. A limited space 164 is formed above the bottom hole 162 to accommodate the light guide plate 154. The light guide plate 154 may be positioned at a relatively high position above the light source 34. The light guide plate 154 may have a light guide hole 155 corresponding to the protruding structure 204. The light shielding sheet 206 may have a light-transmitting area 27 and a avoidance hole 207 is formed corresponding to the protruding structure 204. Through the above configuration, the protruding structure 32 can maintain a safe distance from the light source 34, avoiding problems derived from the interference between the protruding structure 32 and the light source 34. At the same time, the height of the light source 34 is greatly reduced, so that the top surface of the light source 34 with a higher light output ratio is lowered to the bottom surface close to the light guide plate 154 in Figure 8. In this way, the larger distance between the protruding structure 32 and the light source 34 can give the light an opportunity to open the transmission angle and increase the lateral transmission component; ultimately, it contributes to the uniformity and aesthetic effect of the main character/sub-character luminescence and the surrounding halo of the key cap 20. As for other related descriptions of this embodiment (such as the configuration of the reflective ink layer and the mask layer, the design of the glue layer, etc.), it can be referred to the above embodiment by analogy, and will not be repeated here.

In practical applications, in order to further improve the problem of the middle characters being too bright, the present invention may adopt a microstructure layer clearance design. For example, please refer to FIG. 9, which is a top perspective view of the configuration of the key cap 20, the base plate 14, the light source 34 and the microstructure layer 36' according to another embodiment of the present invention. As can be seen from FIG. 9, the backlight module of the present invention may include a microstructure layer 36', which may be formed at a position corresponding to the light-transmitting area 27 (simplified by a dotted line in FIG. 9) of the light-shielding sheet 26 to guide light from the light guide plate 28 through the light-transmitting area 27 and illuminate the keycap 20, and the microstructure layer 36' may define a microstructure clear area 37 (presented as a rectangular area in FIG. 9, but not limited thereto, and may also be designed in other shapes, such as a circular area, etc.) with the light source 34 as the center. The microstructure clear area 37 at least covers the inner portion 15a of the plurality of through holes 15 of the bottom plate 14, so that light will not be emitted from the inner portion 15a of the plurality of through holes 15 through the microstructure layer 36'. The microstructure layer 36' may be parallel to the light guide plate 28 (e.g., formed on the upper surface or lower surface of the light guide plate 28, but not limited thereto, and may also be formed on the light panel 30) and may adopt a dot structure design (but not limited thereto, and may also adopt other optical scattering designs, such as metal paint/white paint design, concave-convex microdot structure design, continuous line microstructure design, etc.), and the microstructure layer 36' may adopt a configuration of removing the optical scattering structure in the microstructure clear area 37. Thus, through the above-mentioned microstructure layer clearance design, the present invention can reduce the light from the light source 34 directly incident upward on the key cap 20, thereby solving the problem mentioned in the prior art that the light emitted upward by the light-emitting diode directly incidents on the backlight key, resulting in uneven character brightness, thereby greatly improving the uniformity of the backlight key lighting and the visual aesthetic effect when in use. In addition, the protruding structure 32 and the glue layer 44 of the above-mentioned embodiments can overlap with the microstructure clearance area 37, or the inner part 15a of the plurality of through holes 15 covered by the microstructure clearance area 37 surrounds the protruding structure 32 and the glue layer 44, further improving the overall uniformity of the light and the visual effect of the key cap 20 character and outline halo.

Regarding the shape of the protruding structure, it may have both an upper convex part and a lower convex part. For example, although the lower convex part is formed by mold stamping, the lower convex part may be lifted by the light source during assembly, so that the lower convex part moves upward, and the annular turning part where the mold applies greater force moves upward to become an upper convex part. Alternatively, in order to avoid interference between the protruding structure and the light source, the stamping mold is deliberately designed to form an upper convex part and a lower convex part at one time. Please refer to Figure 11, which is a partial cross-sectional schematic diagram of a backlight module of another embodiment of the present invention. The protruding structure 32 of the backlight module 18 is formed on the light shielding sheet 26. In addition to the lower convex part 32a, the protruding structure 32 also has a part surrounding the lower convex part 32a that protrudes to form an upper convex part 32b, which is the two protruding corners in the cross-sectional view of Figure 11. The inner reflection area 38a and the inner mask area 40a on the light shielding sheet 26 may protrude upward or downward, or not protrude, depending on the size of the upper convex portion 32b and the lower convex portion 32a. The lower convex portion 32a may still have a small part entering the light guide hole 29, or may not enter the light guide hole 29 at all, and maintain a certain distance from the light source 34. The upper convex portion 32b may partially enter the through hole 15 of the bottom plate 14, or may not be higher than the lower surface of the bottom plate 14. The protruding structure 32 also includes a side arc portion 32c surrounding the outer side of the upper convex portion 32b, which is an arc-shaped surface accompanying the upper convex portion 32b. The lower convex portion 32a and the side arc portion 32c overlap with the inner reflection area 38a of the second reflection layer 38; the inner reflection area 38a can be located on the lower surface or upper surface of the transparent substrate of the light shielding sheet 26. In addition, there is a rubber layer 44 surrounding the outer side of the arc portion 32c to reduce the light escaping in the air gap between the light shielding sheet 26 and the light guide plate 28, or escaping in the air gap between the light guide plate 28 and the light board 30. The arc portion 32c protrudes toward the light source 34 and can be regarded as another additional convex portion 32a, which increases the overall area of the protruding arc surface of the protruding structure 32 toward the light source 34; the convex portion 32a and the arc portion 32c are respectively matched with the internal reflection area 38a to form a structure similar to a convex mirror. In addition, the first reflective layer 42 of the light board 30 at least partially enters the light guide hole 29 of the light guide plate 28, the first reflective layer 42 surrounds the light source 34 in the light guide hole 29, and the first reflective layer 42, the protruding structure 32 and the light guide hole 29 at least partially overlap, so that at the initial stage of light emission, the light reflected downward from the protruding structure 32 can be further reflected and diffused by the first reflective layer 42, and the light reflected upward from the first reflective layer 42 can also be further reflected and diffused by the protruding structure 32, so that more light has the opportunity to directly enter the light horizontally from the hole wall of the light guide plate 28. In this way, the light just emitted by the light source 34 can be reflected and diffused, and the light transmission angle can be opened or increased, so that the light can have a larger lateral transmission component, so that more light enters the light guide plate 28 at the beginning of light emission, and is transmitted horizontally in the light guide plate 28 through total reflection, thereby improving the luminous uniformity and aesthetic effect of the main/sub-characters and outline halo of the keycap 20.

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: Backlit buttons

12: Keyboard

14: Base plate

15:Through hole

16: Thin film circuit board

18: Backlight module

20: Keycaps

22: Lifting mechanism

24: Reset piece

26: Shading film

27: Translucent area

28: Light guide plate

29: Light guide hole

30: Light board

32: Protruding structure

34: Light source

36: Microstructure layer

38: Second reflective layer

38a: Internal reflection area

38b: External reflection area

38c: Rib reflexology area

40: Mask layer

40a: Inner mask area

40b: Outer mask area

40c: Rib mask area

42: First reflection layer

44: Adhesive layer

45: No glue area

S1: Upper surface

S2: Lower surface

Claims (27)

A backlight key, comprising: a key cap; a bottom plate, located below the key cap; a thin film circuit board, arranged parallel to the key cap and the bottom plate; and a backlight module, arranged below the bottom plate, the backlight module comprising: a light shielding sheet, having a light-transmitting area corresponding to the key cap; a light guide plate, arranged below the light shielding sheet; a light board, arranged below the light guide plate and having a light source; and a protruding structure, protruding toward the light source, and formed on one of the bottom plate, the thin film circuit board and the light shielding sheet, the protruding structure reflects and diffuses at least part of the light of the light source to enter the light guide plate for lateral transmission. The backlight key as described in claim 1, wherein the backlight module further comprises: a first reflective layer formed on the light panel, the first reflective layer at least partially overlaps with the protruding structure in the vertical direction. A backlit key as described in claim 2, wherein the light guide plate has a light guide hole for accommodating the light source, and the first reflective layer at least partially overlaps the light guide hole in the vertical direction. A backlight key as described in claim 1, wherein the backlight module further comprises a second reflective layer formed on the light shielding film, and the second reflective layer at least partially overlaps with the protruding structure in the vertical direction. A backlit key as described in claim 1, wherein the base plate has a plurality of through holes surrounding the protruding structure in the vertical direction. A backlight key as described in claim 1, wherein the protruding structure is located on the bottom plate, and the light shielding sheet has a avoidance hole to accommodate the protruding structure. A backlight key as described in claim 1, wherein the protruding structure is located on the thin film circuit board, and the base plate has a through hole to accommodate the protruding structure. A backlight module is used to illuminate at least one keycap, the backlight module comprises: a light shielding sheet having a light-transmitting area; a light guide plate disposed under the light shielding sheet; a light plate disposed under the light guide plate and having a light source; and a protruding structure formed on the light shielding sheet and protruding toward the light source, the protruding structure reflects and diffuses at least part of the light from the light source to enter the light guide plate for lateral transmission. A backlight module as described in claim 8, wherein the backlight module further comprises a first reflective layer formed on the light panel, and the first reflective layer at least partially overlaps with the protruding structure in the vertical direction. The backlight module as described in claim 9, wherein the light guide plate has a light guide hole to accommodate the light source, and the first reflective layer at least partially overlaps the light guide hole in the vertical direction. A backlight module as described in claim 8, wherein the backlight module further comprises an internal reflection area formed on the light shielding film, and the internal reflection area at least partially overlaps with the protruding structure in the vertical direction. The backlight module as described in claim 11, wherein the light guide plate has a light guide hole to accommodate the light source, and the internal reflection area at least partially overlaps the light guide hole in the vertical direction. A backlight module as described in claim 11, wherein the backlight module further comprises an inner masking area formed above the inner reflection area, and the inner masking area overlaps with the protruding structure in the vertical direction. A backlight module as described in claim 8, wherein the light guide plate has a light guide hole corresponding to the protruding structure, and the light source is disposed in the light guide hole. A backlight module as described in claim 8, wherein the backlight module further comprises at least one glue layer at least partially surrounding the protruding structure in the vertical direction. The backlight module as described in claim 15, wherein the light guide plate has a light guide hole, and a non-glue area is provided between the at least one glue layer and the light guide hole of the light guide plate. The backlight module as described in claim 8, wherein the backlight module further comprises a supporting frame disposed between the light board and the light guide plate, the supporting frame is formed with a bottom hole to accommodate the light source, and a limiting space is formed above the bottom hole to accommodate the light guide plate. A backlight module as described in claim 8, wherein the backlight module further comprises a microstructure layer formed on the light guide plate or the light panel. The backlight module as described in claim 8, wherein the protruding structure includes an upper convex portion and a lower convex portion, wherein the lower convex portion protrudes toward the light source and the upper convex portion protrudes away from the light source. A backlight module as described in claim 19, wherein the upper convex portion surrounds the outer side of the lower convex portion. The backlight module as described in claim 19, wherein the protruding structure further includes a side arc portion surrounding the outer side of the convex portion. A backlight key, comprising: a key cap; a bottom plate, located below the key cap; and a backlight module, disposed below the bottom plate, the backlight module comprising: a light shielding sheet, having a light-transmitting area; a light guide plate, disposed below the light shielding sheet; a light plate, disposed below the light guide plate and having a light source; a microstructure layer, comprising a plurality of microstructures corresponding to the light-transmitting area of the light shielding sheet, the microstructure layer further defining a microstructure clear area surrounding the light source, the plurality of microstructures surrounding the microstructure clear area; and a protruding structure, formed on the light shielding sheet and protruding toward the light source, the protruding structure overlaps with the microstructure clear area, and the protruding structure reflects and diffuses at least a portion of the light source to enter the light guide plate for lateral transmission. As described in claim 22, the backlight key, wherein the base plate has a plurality of light-transmissive through holes corresponding to the light-transmissive area of the light-shielding film. A backlight key as described in claim 23, wherein the plurality of through holes each have an inner portion, and the plurality of inner portions at least partially overlap with the microstructure clear area. A backlight key as described in claim 24, wherein the backlight module further comprises a glue layer between the protruding structure and the plurality of inner portions of the base plate. A backlight key as described in claim 22, wherein the backlight module further comprises a glue layer, and the microstructure clear area is at least partially located between the glue layer and the plurality of microstructures. As described in claim 26, the backlight key, wherein the backlight module further comprises an internal reflection area formed on the light shielding film at a position corresponding to the light source, and the microstructure clear area is at least partially located between the internal reflection area and the plurality of microstructures.