TWI665704B - Backlight apparatus used in illuminated keyboard - Google Patents

Abstract

The invention discloses a backlight device used in a light-emitting button. The illuminated keyboard contains multiple keys. The backlight device according to the present invention includes a light guide plate, a light source, a light shielding sheet, and a reflective sheet. The light shielding sheet includes a covering portion and a plurality of first protruding portions. The reflective sheet includes a central portion and a plurality of second protruding portions. The covering portion of the light shielding sheet is attached to the front surface of the light guide plate. The central portion of the reflective sheet is attached to the rear surface of the light guide plate. Each first protruding portion is placed between two adjacent second protruding portions, and is bent to fit on the outer side surface of the light guide plate and the central portion of the reflective sheet. Each second protruding portion is interposed between two adjacent first protruding portions, and is bent to fit on the outer side surface of the light guide plate and the covering portion of the light shielding sheet.

Description

Backlight device for illuminated keyboard

The invention relates to a backlight device used in a light-emitting keyboard, and more particularly, to a backlight device that avoids light leakage and effectively recovers unused light.

Illuminated keyboards are common input peripheral devices on the market. Some of the prior art backlight devices for light-emitting keyboards use a large number of light sources (generally light-emitting diodes) to be arranged along the short side or the long side of the light guide plate. In other prior arts, the light guide plate has an opening, and the light source is placed in the opening of the light guide plate. The light emitted by the light source enters the light guide plate from the short side, the long side of the light guide plate, or the inner side wall of the opening. The light is guided by the light guide plate and exits from the light exit area defined on the front surface of the light guide plate.

Please refer to FIG. 1, which is a partial cross-sectional view of a backlight device 1 of the prior art. The backlight device 1 of the prior art includes a light guide plate 10, a light shielding sheet 12, and a light reflecting sheet 14. The light guide plate 10 includes a front surface 102 and a rear surface 104. The backlight device 1 of the prior art further includes a light source (not shown in FIG. 1). The light source is used to emit light. The light source is arranged to cause light to enter the light guide plate 10. The light incident into the light guide plate 10 is guided by the light guide plate 10 to the front surface 102 of the light guide plate 10, and is then emitted from a plurality of light emitting areas (not shown in FIG. 1) on the front surface 102 of the light guide plate 10.

The light shielding sheet 12 includes a covering portion 122 and a first covering portion 124. The covering portion 122 of the light shielding sheet 12 has a plurality of light transmitting portions (not shown in FIG. 1) thereon. The first covering portion 124 of the light shielding sheet 12 is oriented toward the edge of the covering portion 122. Outside extension. Each light-transmitting portion of the covering portion 122 corresponds to a light-emitting area of the light guide plate 10. The cover portions 122 of the 12 light shielding sheets are attached to the front surface 102 of the light guide plate 10 so that each light transmitting portion is aligned with its corresponding light emitting area. Outside. The reflective sheet 14 includes a central portion 142 and a second covering portion 144. The second covering portion 144 of the reflective sheet 14 extends outward from an edge of the central portion 142. The central portion 142 of the reflective sheet 14 is attached to the back surface 104 of the light guide plate 10, so that the second covering portion 144 of the reflective sheet 14 is also suspended from the edge of the light guide plate 10. The first covering portion 124 of the light shielding sheet 12 and the second covering portion 144 of the reflective sheet 14 are bonded together. Here, the edge of the light guide plate 10 is the outermost edge of the light guide plate 10 or the edge of a through hole formed in the light guide plate 10.

Actually, the backlight device 1 of the prior art has tolerances in assembly. It is likely that, as shown in FIG. 1, the edge of the first covering portion 124 of the light shielding sheet 12 and the edge of the second covering portion 144 of the reflective sheet 14 are not bonded together. The hardened adhesive 16 is exposed on the exposed first covering portion 124 or the exposed second covering portion 144. For example, in FIG. 1, the hardened adhesive 16 is exposed on the exposed second covering portion 144. on. The hardened adhesive 16 becomes a channel through which unused light (the arrow indicated in FIG. 1 represents unused light) is leaked.

Obviously, there is still room for improvement in the design of the prior art backlight device in how to avoid light leakage and effectively recover unused light.

Therefore, one technical problem to be solved by the present invention is to provide a backlight device used in a light-emitting keyboard. The backlight device according to the present invention can avoid light leakage and effectively recover unused light.

The backlight device according to a preferred embodiment of the present invention is used in a light-emitting keyboard, and the light-emitting keyboard includes a plurality of keys. A backlight device according to a preferred embodiment of the present invention includes a light guide plate, a light source, a light shielding sheet, and a reflective sheet. The light guide plate has a front surface, a back surface, and an outer edge side surface. Positive of the light guide plate A plurality of light emitting areas are defined thereon. Each light emitting area corresponds to a button. The light source is used to emit light. The light source is arranged to cause light to enter the light guide plate. The light entering the light guide plate is guided by the light guide plate to the front surface of the light guide plate, and then exits from the light emitting areas on the front surface of the light guide plate. The light shielding sheet includes a covering portion and a plurality of first protruding portions. The covering portion of the light shielding sheet has a plurality of light transmitting portions thereon. The plurality of first protruding portions of the light-shielding sheet extend outward at a first predetermined position of the first edge of the cover portion of the light-shielding sheet and are spaced apart from each other by a first pitch. Each light transmitting portion corresponds to a light emitting area. The covering portion of the light shielding sheet is attached to the front surface of the light guide plate, so that each light transmitting portion is aligned with its corresponding light emitting area. The reflective sheet includes a central portion and a plurality of second protruding portions. The plurality of second protruding portions of the reflective sheet extend outward at a second predetermined position of the second edge of the central portion of the reflective sheet and are spaced apart from each other by a second pitch. The second predetermined position corresponds to the first predetermined position. The central portion of the light reflecting sheet is adhered to the rear surface of the light guide plate. The first width of each first protruding portion of the light shielding sheet is equal to the second pitch, and the second width of each second protruding portion of the light reflecting sheet is equal to the first pitch. Each of the first protruding portions of the light shielding sheet is disposed between the second protruding portions of two adjacent reflective sheets, and is bent to fit on the outer side surface of the light guide plate and the central part of the reflective sheet. Each of the second protruding portions of the light-reflecting sheet is disposed between the first protruding portions of two adjacent light-shielding sheets, and is bent to fit on the outer side surface of the light guide plate and the covering part of the light-shielding sheet.

In a specific embodiment, a light shielding sheet of a backlight device according to a preferred embodiment of the present invention further includes a first covering portion. The first covering portion of the light shielding sheet extends outward from the first edge of the covering portion except at a first predetermined position. The reflective sheet further includes a second covering portion. The second covering portion of the reflective sheet extends outward from the second edge of the central portion except at a second predetermined position. The first covering portion of the light shielding sheet and the second covering portion of the reflective sheet are bonded together.

Further, the light guide plate of the backlight device according to a preferred embodiment of the present invention further has a first through hole. The shielding portion of the light shielding sheet has a second through hole thereon. The central portion of the reflective sheet has a third through hole thereon. Second through hole of cover The third through hole corresponding to the central portion corresponds to the first through hole of the light guide plate. The light shielding sheet further includes a third covering portion surrounding the second through hole and a plurality of third protruding portions. The plurality of third protruding portions of the light shielding sheet extend inwardly from the third covering part of the light shielding sheet and are spaced apart from each other at a third pitch. The reflective sheet further includes a fourth covering portion surrounding the third through hole and a plurality of fourth protruding portions. The plurality of fourth protruding portions of the reflective sheet extend inwardly from the fourth covering portion of the reflective sheet and are spaced from each other at a fourth pitch. The third width of each third protruding portion of the light shielding sheet is equal to the fourth pitch. A fourth width of each of the fourth protruding portions of the reflective sheet is equal to a third pitch. The third covering part of the light shielding sheet and the fourth covering part of the reflective sheet are placed in the first through hole of the light guide plate and are bonded together. Each third protruding portion of the light-shielding sheet is disposed between the fourth protruding portions of two adjacent reflective sheets, and is bent to fit on the fourth covering portion of the reflective sheet. Each of the fourth protruding portions of the light-reflecting sheet is disposed between the third protruding portions of two adjacent light-shielding sheets, and is bent to fit on the third covering part of the light-shielding sheet.

Further, the backlight device according to a preferred embodiment of the present invention further includes a plurality of light turning structures. The plurality of light turning structures are formed on the back of the light guide plate and are located under the plurality of light emitting areas, and are used to guide the light rays directed to the plurality of light turning structures to the front face of the light guide plate, and then from the front of the light guide plate Wait for the light to exit.

Unlike the prior art, the backlight device of the present invention can avoid light leakage and effectively recover unused light.

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

1‧‧‧ backlight

10‧‧‧light guide

102‧‧‧ Positive

104‧‧‧Back

12‧‧‧ Shading film

122‧‧‧ Covering Department

124‧‧‧The first coating section

14‧‧‧Reflector

142‧‧‧ Central

144‧‧‧Second coating section

16‧‧‧hardened viscose

2‧‧‧ illuminated keyboard

20‧‧‧Keyboard Department

202‧‧‧button

22‧‧‧ substrate

222‧‧‧Positioning post

3‧‧‧ backlight

30‧‧‧light guide

300‧‧‧ Front

301‧‧‧ side of outer edge

302‧‧‧Back

303‧‧‧ opening

304‧‧‧ side of outer edge

306‧‧‧Illuminating area

308‧‧‧First through hole

32‧‧‧ light source

322‧‧‧Circuit Board

324‧‧‧light-emitting element

34‧‧‧shield

340‧‧‧ cover

3402‧‧‧Light Transmission Department

3404‧‧‧First Edge

3406‧‧‧First scheduled location

3408‧‧‧Second Through Hole

341‧‧‧First protrusion

342‧‧‧The first coating section

343‧‧‧third coating

344‧‧‧Third protrusion

36‧‧‧Reflector

360‧‧‧ Central

3602‧‧‧Second Edge

3604‧‧‧Second Scheduled Position

3606‧‧‧Third through hole

3608‧‧‧through opening

361‧‧‧ second protrusion

362‧‧‧Second coating section

363‧‧‧Fourth Covering Department

364‧‧‧Fourth protrusion

38‧‧‧light turning structure

d1‧‧‧first pitch

d2‧‧‧Second Spacing

d3‧‧‧third distance

d4‧‧‧ Fourth pitch

w1‧‧‧first width

w2‧‧‧ second width

w3‧‧‧ third width

w4‧‧‧ fourth width

FIG. 1 is a partial cross-sectional view of a backlight device of the prior art.

FIG. 2 is a light-emitting keyboard using a backlight device according to a preferred embodiment of the present invention Expanded view of the components.

FIG. 3 is a partial enlarged view of the backlight device of FIG. 2 assembled and corresponding to a first predetermined position of the light shielding sheet and a second predetermined position of the reflective sheet.

FIG. 4 is a partial cross-sectional view of the backlight device of FIG. 2 assembled and corresponding to the first through hole of the light guide plate, the second through hole of the light shielding sheet, and the third through hole of the reflective sheet.

Please refer to FIG. 2, FIG. 3 and FIG. 4. FIG. 2 is a schematic diagram showing a light emitting keyboard 2 using a backlight device 3 according to a preferred embodiment of the present invention in an element development view. FIG. 3 is a partial enlarged view of the backlight device 3 of FIG. 2 assembled and corresponding to a first predetermined position 3406 of the light shielding sheet 34 and a second predetermined position 3604 of the reflective sheet 36. FIG. 4 is a partial cross-sectional view of the assembled backlight device 3 of FIG. 2 and corresponding to the first through hole 308 of the light guide plate, the second through hole 3408 of the light shielding sheet 34 and the third through hole 3606 of the light reflecting sheet 36.

As shown in FIG. 2, the light-emitting keyboard 2 using the backlight device 3 of the present invention includes a substrate 22, the backlight device 3 of the present invention, and a keyboard portion 20. The backlight device 3 is provided on the substrate 22, and the keyboard portion 20 is provided on the backlight device 3. The keyboard section 20 includes a plurality of keys 202.

The backlight device 3 according to a preferred embodiment of the present invention includes a light guide plate 30, a light source 32, a light shielding sheet 34, and a light reflecting sheet 36.

The light guide plate 30 includes a front surface 300, a rear surface 302, and an outer edge side surface 304. The front side 300 of the light guide plate 30 defines a plurality of light emitting areas 306 thereon. Each light emitting area 306 corresponds to a button 202. It should be stated here that the plurality of light emitting areas 306 are not physical structures, but are predetermined areas.

In a specific embodiment, the light guide plate 30 may be made of acrylic, silicone, thermoplastic polyurethane (TPU), or other commercially available polymer materials with good light guiding properties. to make.

The light source 32 is used to emit light. The light source 32 is arranged to cause light to enter the light guide plate 30. For example, in the example shown in FIG. 2, the light guide plate 30 further has a plurality of openings 303. The openings 303 are formed on the back surface 302 of the light guide plate 30 and are close to the outer edge side surface 301 of the long side of the light guide plate 30. In FIG. 1, the openings 303 are close to the long side 301 of the light guide plate 30, but the invention is not limited thereto. Each opening 303 has its own light incident surface. The light source 32 includes a circuit board 322 and a plurality of light emitting elements 324. The plurality of light emitting elements 324 are electrically connected to the circuit board 322. Each light-emitting element 324 corresponds to one opening 303. The light source 32 is disposed on the back surface 302 of the light guide plate 30, so that each light-emitting element 324 is placed in its corresponding opening 303. In FIG. 2, the reflective sheet 36 has an opening 3608 therethrough, and the light source 32 is disposed in the opening 3608. The light emitted by each light-emitting element 324 enters the light guide plate 30 from the light incident surface of its corresponding opening 303 and is conducted inside the light guide plate 30. The light source 32 may also be provided with an outer edge side surface 304 abutting on the short side of the light guide plate 30 or with an outer edge side surface 301 close to the long side of the light guide plate 30.

In a specific embodiment, the circuit board 322 may be a flexible circuit board, but the invention is not limited thereto.

In a specific embodiment, each light-emitting element 324 may be a semiconductor light-emitting diode or an organic light-emitting diode, but the present invention is not limited thereto.

The light incident into the light guide plate 30 is guided by the light guide plate 30 to the front surface 300 of the light guide plate 30, and is then emitted from the light emitting areas 306 on the front surface 300 of the light guide plate 30.

Further, the backlight device 3 according to a preferred embodiment of the present invention further includes a plurality of light turning structures 38. The plurality of light redirecting structures 38 are formed on the back surface 302 of the light guide plate 30 and are located under the plurality of light exiting areas 306 for directing the light rays directed to the plurality of light redirecting structures 38 to the light guide plate 30. The surface 300 is emitted from the light emitting regions 306 on the front surface 300 of the light guide plate 30.

In a specific embodiment, the plurality of light turning structures 38 may be formed by printing dot-shaped light-colored (eg, white) ink on the back surface 302 of the light guide plate 30, micro-lens, or plating may also be used. It is integrally formed with the light guide plate 30. However, the formation of the plurality of light turning structures 38 is not limited to the above process.

As shown in FIGS. 2 and 3, the light shielding sheet 34 includes a covering portion 340 and a plurality of first protruding portions 341. The covering portion 340 of the light shielding sheet 34 has a plurality of light transmitting portions 3402 thereon. The plurality of light transmitting portions 3402 may be a hollow structure, but it is not limited thereto. The plurality of first protruding portions 341 of the light shielding sheet 34 extend outward from a first predetermined position 3406 of the first edge 3404 of the cover portion 340 of the light shielding sheet 34 and are spaced apart from each other by a first pitch d1. Each light transmitting portion 3402 corresponds to a light emitting area 306. The cover portion 340 of the light shielding sheet 34 is attached to the front surface 300 of the light guide plate 30, so that each light transmitting portion 3402 is aligned with its corresponding light emitting area 306.

As shown in FIGS. 2 and 3 as well, the reflective sheet 36 includes a central portion 360 and a plurality of second protruding portions 361. The plurality of second protruding portions 361 of the reflective sheet 36 extend outward from the second predetermined position 3604 of the second edge 3602 of the central portion 360 of the reflective sheet 36 and are spaced apart from each other by a second pitch d2. The second predetermined position 3604 corresponds to the first predetermined position 3406. A central portion 360 of the reflective sheet 36 is attached to the back surface 302 of the light guide plate 30.

As shown in FIG. 3, the first width w1 of each of the first protruding portions 341 of the light shielding sheet 34 is equal to the second pitch d2, and the second width w2 of each of the second protruding portions 361 of the reflective sheet 36 is equal to the first pitch d1. Each of the first protruding portions 341 of the light shielding sheet 34 is disposed between the second protruding portions 361 of two adjacent reflective sheets 36, and is bent to fit on the outer side surface 304 of the light guide plate 30 and the reflective sheet 36. The central part 360. Each second protrusion of the reflective sheet 36 The portion 361 is disposed between the first protruding portions 341 of the two adjacent light shielding sheets 34, and is bent and attached to the outer side surface 304 of the light guide plate 30 and the cover portion 340 of the light shielding sheet 34. Thereby, the light emitted from the backlight device 3 to the first protruding portion 341 and the second protruding portion 361 according to the present invention will not leak out, and the unused light can be effectively recovered and reused.

In a specific embodiment, as shown in FIG. 2, the first predetermined position 3406 is located between two adjacent transparent portions 3402 near the first edge 3404 of the cover portion 340 of the light shielding sheet 34. After the backlight device 3 according to the present invention is assembled, the first predetermined position 3406 is also located between two adjacent light transmitting portions 3402 near the outer side surface 304 of the light emitting area 306. In general, the light transmitted in the light guide plate 30 between two adjacent light-exiting regions 306 is used at a lower rate and must be effectively recovered.

In a specific embodiment, as shown in FIGS. 2 and 3, the light shielding sheet 34 of the backlight device 3 according to a preferred embodiment of the present invention further includes a first covering portion 342. The first covering portion 342 of the light shielding sheet 34 extends outward from the first edge 3404 of the covering portion 340 except for the first predetermined position 3406. The reflective sheet 36 further includes a second covering portion 362. The second covering portion 362 of the reflective sheet 36 extends outward from the second edge 3602 of the central portion 360 except for the second predetermined position 3604. The first covering portion 342 of the light shielding sheet 34 and the second covering portion 362 of the reflective sheet 36 are bonded together.

In another embodiment, the backlight device 3 according to a preferred embodiment of the present invention does not include a first covering portion 342 in the light shielding sheet 34 and a second covering portion 362 in the reflective sheet 36, and a plurality of first protrusions The portion 341 surrounds all the first edges 3404 of the cover portion 340, and the plurality of second protruding portions 361 surround all the second edges 3602 of the central portion 360.

In another specific embodiment, a plurality of first protruding portions 341 extend outward between two adjacent transparent portions 3402 of the first edge 3404 of the covering portion 340. The reflective sheet 36 also has a plurality of second protrusions at corresponding positions. 361 extends outward.

Further, as shown in FIGS. 2 and 4, the light guide plate 30 of the backlight device 3 according to a preferred embodiment of the present invention further has a first through hole 308. The cover portion 340 of the light shielding sheet 34 has a second through hole 3408 thereon. The central portion 360 of the reflective sheet 36 has a third through hole 3606 thereon. The second through hole 3408 of the cover portion 340 and the third through hole 3606 of the central portion 360 both correspond to the first through hole 308 of the light guide plate 30. Correspondingly, a positioning post 222 is formed on the substrate 22. The positioning post 222 passes through the first through hole 308, the second through hole 3408, and the third through hole 3606. In practical applications, a plurality of positioning posts 222 are formed on the substrate 22. Correspondingly, the light guide plate 30 has a plurality of first through holes 308, the covering portion 340 has a plurality of second through holes 3408 thereon, and the central portion 360 has There are a plurality of third through holes 3606 thereon. In FIG. 2, only one first through hole 308, one second through hole 3408, and one third through hole 3606 are shown as representatives.

In FIG. 4, for clarity, only a part of the light guide plate 30, a part of the light shielding sheet 34, and a part of the reflective sheet 36 are shown. The rest of the first through-hole 308, the second through-hole 3408, and the third through-hole 3606 are shown by dashed lines. . As shown in FIG. 4, the light shielding sheet 34 further includes a third covering portion 343 surrounding the second through hole 3408 and a plurality of third protruding portions 344. The plurality of third protruding portions 344 of the light shielding sheet 34 extend inwardly from the third covering portion 343 of the light shielding sheet 34 and are spaced apart from each other by a third pitch d3. The reflective sheet 36 further includes a fourth covering portion 363 surrounding the third through hole 3606 and a plurality of fourth protruding portions 364. The plurality of fourth protruding portions 364 of the reflective sheet 36 extend inwardly from the fourth covering portion 363 of the reflective sheet 36 and are spaced from each other at a fourth pitch d4. A third width w3 of each third protruding portion 344 of the light shielding sheet 34 is equal to a fourth pitch d4. A fourth width w4 of each of the fourth protruding portions 364 of the reflective sheet 36 is equal to a third pitch d3. The third covering portion 343 of the light shielding sheet 34 and the fourth covering portion 363 of the reflective sheet 36 are placed in the first through hole 308 of the light guide plate 30 and are bonded together. Each of the third protruding portions 344 of the light shielding sheet 34 is disposed between the fourth protruding portions 364 of two adjacent reflective sheets 36, and is bent to fit the fourth covering of the reflective sheet 36. Department 363. Each of the fourth protruding portions 364 of the light reflecting sheet 36 is disposed between the third protruding portions 344 of two adjacent light shielding sheets 34, and is bent and fits on the third covering portion 343 of the light shielding sheet 34. Thereby, the light emitted from the backlight device 3 according to the present invention at the first through hole 308 of the light guide plate 30 will not leak out, and the unused light can be effectively recycled and reused.

From the above detailed description of the present invention, it can be clearly understood that the backlight device of the present invention can avoid light leakage and effectively recover unused light.

With the above detailed description of the preferred embodiments, it is hoped that the features and spirit of the present invention may be more clearly described, rather than limiting the aspects of the present invention with the preferred embodiments disclosed above. On the contrary, the intention is to cover various changes and equivalent arrangements within the scope of the patent scope of the present invention. Therefore, the aspect of the patent scope of the present invention should be explained in the broadest sense according to the above description, so that it covers all possible changes and equal arrangements.

Claims (10)

A backlight device for use in a light-emitting keyboard, the light-emitting keyboard comprising a plurality of keys, the backlight device comprising: a light guide plate having a front surface, a back surface and an outer edge side, the front surface defining a plurality of light emitting areas thereon; Each light emitting area corresponds to a button; a light source is used to emit a light, the light source is arranged to cause the light to enter the light guide plate, the light is guided by the light guide plate to the front surface, and then from the front surface to the Wait for the light emitting area to emit; a light shielding sheet including a covering portion and a plurality of first protruding portions, the covering portion having a plurality of light transmitting portions thereon, the plurality of first protruding portions being tied to a first edge of the covering portion One of the first predetermined positions extends outward and is spaced apart from each other by a first interval. Each light transmitting portion corresponds to a light emitting area, and the covering portion is attached to the front surface so that each light transmitting portion is aligned with its corresponding light output. Area; and a reflective sheet including a central portion and a plurality of second protruding portions, the plurality of second protruding portions extend outward at a second predetermined position of a second edge of the central portion The second predetermined position corresponds to the first predetermined position, and the central portion is attached to the back surface; wherein a first width of each of the first protruding portions is equal to the second distance, each One of the second protrusions has a second width equal to the first distance, and each of the first protrusions is placed between two adjacent second protrusions and is bent to fit the side surface of the outer edge and the central portion. Each of the second protruding portions is placed between two adjacent first protruding portions and bent to fit on the side surface of the outer edge and the covering portion. The backlight device according to claim 1, wherein the first predetermined position is located between two adjacent light transmitting portions near the first edge of the covering portion. The backlight device according to claim 2, wherein the light-shielding sheet further includes a first covering portion, and the first covering portion extends from the first edge of the covering portion except for the first predetermined position, The reflective sheet further includes a second covering portion, the second covering portion is extended from the second edge of the central portion outwardly at the second predetermined position, and the first covering portion and the second covering portion The overlays fit together. The backlight device according to claim 3, wherein the light guide plate further has a first through hole, the covering portion has a second through hole thereon, and the central portion has a third through hole thereon, and the second through hole Both the hole and the third through hole correspond to the first through hole, and the light shielding sheet further includes a third covering portion surrounding the second through hole and a plurality of third protruding portions, and the plurality of third protruding portions are connected to The third covering portion extends inwardly and is spaced at a third interval from each other. The reflective sheet further includes a fourth covering portion surrounding the third through hole and a plurality of fourth protruding portions. The four protrusions extend inwardly at the fourth covering portion and are spaced from each other by a fourth pitch. A third width of each third protrusion is equal to the fourth pitch and one of each fourth protrusion. The fourth width is equal to the third pitch. The third covering portion and the fourth covering portion are placed in the first through hole and are attached together. Each third protruding portion is placed in two adjacent areas. The fourth protrusions are bent and fit on the fourth covering portion, and each fourth protrusion is placed in two The adjacent third protruding portions are bent and adhered to the third covering portion. The backlight device according to claim 3, further comprising: a plurality of light redirecting structures formed on the back surface and positioned below the plurality of light emitting areas for guiding the light rays directed toward the plurality of light redirecting structures. The front face is emitted from the light emitting areas on the front face. A backlight device for a light-emitting keyboard includes a plurality of keys. The backlight device includes a light guide plate having a front surface, a back surface, and a first through hole. The front surface defines a plurality of light emitting areas. , Each light emitting area corresponds to a key; a light source for emitting a light, the light source is arranged to cause the light to enter the light guide plate, the light is guided by the light guide plate to the front surface, and then from the front surface The light-emitting areas emit; a light-shielding sheet including a covering portion, the covering portion having a plurality of light-transmitting portions and a second through-hole, each light-transmitting portion corresponds to a light-emitting area, and the second through-hole corresponds to A first through hole, the light shielding sheet further comprising a first covering portion surrounding the second through hole and a plurality of first protruding portions, the plurality of first protruding portions extending inwardly at the first covering portion And are spaced at a first interval from each other, the covering portion is adhered to the front surface so that each light transmitting portion is aligned with its corresponding light emitting area; and a reflective sheet including a central portion having a first portion thereon Tee hole, The third through hole corresponds to the first through hole, and the reflective sheet further includes a second covering portion surrounding the third through hole and a plurality of second protruding portions, and the plurality of second protruding portions are tied to the second package. The covering portions extend inwardly and are spaced apart from each other by a second pitch, and the central portions are attached to the back surface; wherein a first width of each of the first protruding portions is equal to the second pitch, and each of the second protruding portions A second width is equal to the first pitch, the first covering portion and the second covering portion are placed in the first through hole and are attached together, and each first protruding portion is placed in two Between the adjacent second protrusions, they are bent and fit on the second covering part, and each second protrusion is placed between two adjacent first protrusions and bent and fit on the second cover. On the first covering portion. The backlight device according to claim 6, wherein the light guide plate further has an outer side surface, the light shielding sheet further includes a plurality of third protrusions, and the plurality of third protrusions are attached to a first edge of the covering portion. One of the first predetermined positions extends outward and is spaced from each other by a third pitch. The reflective sheet further includes a plurality of fourth protrusions, and the plurality of fourth protrusions are attached to a second edge of the central portion. A second predetermined position extends outward and is spaced from each other by a fourth pitch, the second predetermined position corresponds to the first predetermined position, and a third width of each third protrusion is equal to the fourth pitch, each One of the fourth protrusions has a fourth width equal to the third distance, and each third protrusion is placed between two adjacent fourth protrusions and bent to fit on the side surface of the outer edge and the central portion. , Each fourth protruding portion is placed between two adjacent third protruding portions and bent to fit on the side surface of the outer edge and the covering portion The backlight device according to claim 7, wherein the first predetermined position is located between two adjacent light-transmitting portions near the first edge of the covering portion. The backlight device according to claim 8, wherein the light shielding sheet further includes a third covering portion, and the third covering portion extends outward from the first edge of the covering portion except at the first predetermined position, The reflective sheet further includes a fourth covering portion. The fourth covering portion extends outward from the second edge of the central portion except at the second predetermined position. The third covering portion and the fourth covering portion extend outward. The overlays fit together. The backlight device according to claim 9, further comprising: a plurality of light redirecting structures formed on the back surface and positioned below the plurality of light emitting areas for guiding the light rays directed toward the plurality of light redirecting structures. The front face is emitted from the light emitting areas on the front face.