Backlight apparatus used in illuminated keyboard

Abstract

A backlight apparatus used in an illuminated keyboard includes a light-guiding plate, a strip-shaped flexible circuit board, a plurality of first light-emitting devices, a plurality of second light-emitting devices, and a plurality of third light-emitting device. The light-guiding plate has a plurality of first through holes, a plurality of second through holes and a plurality of third through holes. The strip-shpaed flexible circuit board includes a first strip portion, a second strip portion and a third strip portion. Each first light-emitting device is electrically bonded on a first lower surface of the first strip portion, and is positioned in the corresponding first through hole. Each second light-emitting device is electrically bonded on a third lower surface of the thirdstrip portion, and is positioned in the corresponding second through hole. Each third light-emitting device is electrically bonded on a second upper surface of the second strip portion, and is positioned in the corresponding third through hole.

Description

[Technical Field]

[0001] The present invention relates to a backlight device for an illuminated keyboard, and more particularly to a backlight device for an illuminated keyboard that has the advantages of being energy-saving and low-cost. [Previous Technology]

[0002] Backlit keyboards are now common input peripherals on the market. Early backlighting devices for backlit keyboards arranged a considerable number of light-emitting elements (usually light-emitting diodes) along the longitudinal side (short side) of a light guide plate. However, due to the energy transfer of light within the light guide plate, the energy attenuation is not linearly inversely proportional to the transmission distance; the farther the light travels, the greater the energy loss. Clearly, such prior art backlighting devices exhibit uneven light emission, and dark areas may occur far from the light-emitting elements. Furthermore, such prior art backlighting devices consume a lot of power.

[0003] Please refer to Figure 1, which is a top view of a prior art backlight device 1. The backlight device 1 includes a light guide plate 10, a flexible circuit board 12, and a plurality of light-emitting elements 14. The light guide plate 10 has a lateral side (long side) 101, a top surface 102, a back surface opposite to the top surface 102 (not shown in Figure 1), and two opposing longitudinal sides (103, 104). The light guide plate 10 also has a plurality of through holes 106. In particular, the plurality of through holes 106 are arranged approximately along the centerline perpendicular to the lateral side 101. Each through hole 106 has its own light-incident surface 108. The plurality of light-incident surfaces 108 of the plurality of through holes 106 are alternately oriented toward the two longitudinal sides (103, 104). Each light-emitting element 14 corresponds to one through hole 106. The plurality of light-emitting elements 14 are electrically bonded to the flexible circuit board 12. A flexible circuit board 12 is mounted on the back of the light guide plate 10, such that each light-emitting element 14 is positioned within its corresponding through-hole 106. Each light-emitting element 14 is a side-emitting element. The light emitted by each light-emitting element 14 enters the light guide plate 10 through the light-incident surface 108 of its corresponding through-hole 106, is transmitted within the light guide plate 10, and then exits from the top surface 102 of the light guide plate 10. This results in uniform overall illumination of the prior art backlight device 1, thereby avoiding dark areas. However, the power consumption of such prior art backlight devices 1 remains high. The number of light-emitting elements 14 shown in Figure 1 is only schematic and does not represent the actual number in an example. Generally, the light-emitting elements 14 are light-emitting diodes (LEDs). Taking the example of the backlight device 1 shown in Figure 1 used in a backlit keyboard of a notebook computer, 15 LEDs with a thickness of 0.4 mm are used.

[0004] Furthermore, there is significant room for reducing the manufacturing cost of the flexible circuit board used in the aforementioned backlight device.

[0005] The light-emitting elements used in previous backlight devices were mostly light-emitting diodes. As light-emitting diodes have become miniaturized, sub-millimeter light-emitting diodes (mini-LEDs) and micro light-emitting diodes (micro-LEDs) are now available on the market.

[0006] To reduce the power consumption of prior art backlight devices, backlight devices for backlit keyboards have employed a greater number of sub-millimeter light-emitting diodes (LEDs). Each keycap of the backlit keyboard is equipped with at least one sub-millimeter LED. This results in uniform illumination without dark areas and lower power consumption. For example, a backlight device for a notebook computer's backlit keyboard uses 95 mini-LEDs. However, such prior art backlight devices are more expensive. [Summary of the Invention]

[0007] Therefore, one of the technical problems to be solved by the present invention is to provide a backlight device for an illuminated keyboard. The backlight device for an illuminated keyboard according to the present invention not only provides more uniform light emission, but also has advantages such as power saving and low cost.

[0008] The backlight device according to a first preferred embodiment of the present invention is used for a backlight keyboard. The backlight device according to the first preferred embodiment of the present invention includes a light guide plate, a strip-shaped flexible circuit board, a plurality of first light-emitting elements, a plurality of second light-emitting elements, and a plurality of third light-emitting elements. The light guide plate defines a longitudinal direction and a transverse direction. The light guide plate defines and has a top surface, a back surface opposite to the top surface, a first transverse side, a second transverse side opposite to the first transverse side, a first longitudinal side, a second longitudinal side opposite to the first longitudinal side, a plurality of first through holes, a plurality of second through holes, and a plurality of third through holes. The plurality of first through holes are arranged from the first transverse side along the longitudinal direction and are close to the first longitudinal side. The plurality of second through holes are arranged from the first transverse side along the longitudinal direction and are close to the second longitudinal side. The plurality of third through holes are adjacent to the second transverse side, arranged in the transverse direction, and located between the plurality of first through holes and the plurality of second through holes. Each first through-hole has its own first light-incident surface. The plurality of first light-incident surfaces of the plurality of first through-holes alternately face the second longitudinal side and the first longitudinal side. Each second through-hole has its own second light-incident surface. The plurality of second light-incident surfaces of the plurality of second through-holes alternately face the first longitudinal side and the second longitudinal side. Each third through-hole has its own third light-incident surface. The plurality of third light-incident surfaces of the plurality of third through-holes face the first transverse side. A strip-shaped flexible circuit board includes a first strip portion, a first bent portion connecting the first strip portion, a second strip portion connecting the first bent portion, a second bent portion connecting the second strip portion, and a third strip portion connecting the second bent portion. The first strip portion has a first upper surface and a first lower surface, and defines a first length direction. The second strip portion has a second upper surface and a second lower surface, and defines a second length direction. The third strip portion has a third upper surface and a third lower surface, and defines a third length direction. A plurality of first light-emitting elements are electrically bonded to the first lower surface of the first elongated portion and arranged along the first length direction. Each first light-emitting element corresponds to a first through-hole. A plurality of second light-emitting elements are electrically bonded to the third lower surface of the third elongated portion and arranged along the third length direction. Each second light-emitting element corresponds to a second through-hole. A plurality of third light-emitting elements are electrically bonded to the second upper surface of the second elongated portion and arranged along the second length direction. Each third light-emitting element corresponds to a third through-hole. The first and second bending portions are bent such that the first lower surface of the first elongated portion, the third lower surface of the third elongated portion, and the second upper surface of the second elongated portion are coplanar. The elongated flexible circuit board is placed on the back of the light guide plate with its first lower surface, second upper surface, and third lower surface, such that each first light-emitting element is placed in its corresponding first through-hole, each second light-emitting element is placed in its corresponding second through-hole, and each third light-emitting element is placed in its corresponding third through-hole.Each first light-emitting element emits a first light ray that strikes the first light-incident surface of its corresponding first through-hole, and then enters the light guide plate. Each second light-emitting element emits a second light ray that strikes the second light-incident surface of its corresponding second through-hole, and then enters the light guide plate. Each third light-emitting element emits a third light ray that strikes the third light-incident surface of its corresponding third through-hole, and then enters the light guide plate.

[0009] In one specific embodiment, the first distance between the plurality of first through holes and the first longitudinal side and the second distance between the plurality of second through holes and the second longitudinal side are one-fifth to one-half of the lateral length of the first lateral side.

[0010] Further, the backlight device according to a first preferred embodiment of the present invention also includes a connecting flexible circuit board. The connecting flexible circuit board includes a third bent portion and a fourth elongated portion. The third bent portion is connected to the leading edge of the second elongated portion. The fourth elongated portion is connected to the third bent portion. The third bent portion is bent such that a portion of the fourth elongated portion is in close contact with the second lower surface of the second elongated portion.

[0011] The backlight device according to a second preferred embodiment of the present invention is used for a backlight keyboard. The backlight device according to the second preferred embodiment of the present invention includes a light guide plate, a strip-shaped flexible circuit board, a plurality of first light-emitting elements, a plurality of second light-emitting elements, and a plurality of third light-emitting elements. The light guide plate defines a longitudinal direction and a transverse direction. The light guide plate also has a top surface, a back surface opposite to the top surface, a first transverse side, a second transverse side opposite to the first transverse side, a first longitudinal side, a second longitudinal side opposite to the first longitudinal side, a plurality of first through holes, a plurality of second through holes, and a plurality of third through holes. The plurality of first through holes are arranged from the first transverse side along the longitudinal direction and are close to the first longitudinal side. The plurality of second through holes are arranged from the first transverse side along the longitudinal direction and are close to the second longitudinal side. The plurality of third through holes are arranged in the transverse direction and are located between the plurality of first through holes and the plurality of second through holes, and are close to the second transverse side. Each first through hole has its own first light-incident surface. A plurality of first through-holes have a plurality of first light-incident surfaces that alternately face a second longitudinal side and a first longitudinal side. Each second through-hole has its own second light-incident surface. A plurality of second through-holes have a plurality of second light-incident surfaces that alternately face a first longitudinal side and a second longitudinal side. Each third through-hole has its own third light-incident surface. A plurality of third through-holes have a plurality of third light-incident surfaces that alternately face a first transverse side and a second transverse side. A strip-shaped flexible circuit board includes a first strip portion, a first bend portion connecting the first strip portion, a second strip portion connecting the first bend portion, a second bend portion connecting the second strip portion, and a third strip portion connecting the second bend portion. The first strip portion has a first upper surface and a first lower surface, and defines a first length direction. The second strip portion has a second upper surface and a second lower surface, and defines a second length direction. The third strip portion has a third upper surface and a third lower surface, and defines a third length direction. A plurality of first light-emitting elements are electrically bonded to the first lower surface of the first elongated portion and arranged along the first length direction. Each first light-emitting element corresponds to a first through-hole. A plurality of second light-emitting elements are electrically bonded to the third lower surface of the third elongated portion and arranged along the third length direction. Each second light-emitting element corresponds to a second through-hole. A plurality of third light-emitting elements are electrically bonded to the second upper surface of the second elongated portion and arranged along the second length direction. Each third light-emitting element corresponds to a third through-hole. The first and second bending portions are bent such that the first lower surface of the first elongated portion, the third lower surface of the third elongated portion, and the second upper surface of the second elongated portion are coplanar. The elongated flexible circuit board is placed on the back of the light guide plate with its first lower surface, second upper surface, and third lower surface, such that each first light-emitting element is placed in its corresponding first through-hole, each second light-emitting element is placed in its corresponding second through-hole, and each third light-emitting element is placed in its corresponding third through-hole.Each first light-emitting element emits a first light ray that strikes the first light-incident surface of its corresponding first through-hole, and then enters the light guide plate. Each second light-emitting element emits a second light ray that strikes the second light-incident surface of its corresponding second through-hole, and then enters the light guide plate. Each third light-emitting element emits a third light ray that strikes the third light-incident surface of its corresponding third through-hole, and then enters the light guide plate.

[0012] In one specific embodiment, the first light-incident surface of the first through-hole closest to the second lateral side faces the first longitudinal side and is adjacent to the second lateral side. The third light-incident surface of the third through-hole closest to the first longitudinal side faces the second lateral side and is adjacent to the first longitudinal side. The third light-incident surface of the third through-hole closest to the second longitudinal side faces the second lateral side and is adjacent to the second longitudinal side. The second light-incident surface of the second through-hole closest to the second lateral side faces the second longitudinal side and is adjacent to the second lateral side.

[0013] In one specific embodiment, the first distance between the plurality of first through holes and the first longitudinal side and the second distance between the plurality of second through holes and the second longitudinal side are one-fifth to one-half of the lateral length of the first lateral side.

[0014] In one specific embodiment, the third distance between the plurality of third through holes and the second transverse side is one-fifth to one-half of the longitudinal length of the first longitudinal side.

[0015] Further, the backlight device according to a second preferred embodiment of the present invention also includes a connecting flexible circuit board. The connecting flexible circuit board includes a third bent portion and a fourth elongated portion. The third bent portion is connected to the leading edge of the second elongated portion. The fourth elongated portion is connected to the third bent portion. The third bent portion is bent such that a portion of the fourth elongated portion is in close contact with the second lower surface of the second elongated portion.

[0016] A backlight device according to a third preferred embodiment of the present invention is used for a backlight keyboard. The backlight device according to a third preferred embodiment of the present invention includes a light guide plate, a strip-shaped flexible circuit board, and a plurality of light-emitting elements. The light guide plate defines a longitudinal direction and a transverse direction. The light guide plate also has a top surface, a back surface opposite to the top surface, a first transverse side, a second transverse side opposite to the first transverse side, a first longitudinal side, a second longitudinal side opposite to the first longitudinal side, and a plurality of through holes. The plurality of through holes are arranged in the transverse direction and are located between the first longitudinal side and the second longitudinal side. Each through hole has its own light-incident surface. The plurality of light-incident surfaces of the plurality of through holes alternately face the first transverse side and the second transverse side. The strip-shaped flexible circuit board has an upper surface and a lower surface and defines a length direction. The plurality of light-emitting elements are electrically bonded to the upper surface of the strip-shaped flexible circuit board and are arranged in the length direction. Each first light-emitting element corresponds to one through hole. The elongated flexible circuit board has its upper surface placed on the back of the light guide plate, so that each light-emitting element is placed in its corresponding through-hole. Each light-emitting element emits light that is directed towards the light-incident surface of its corresponding through-hole, and then into the light guide plate.

[0017] In one specific embodiment, the distance between the plurality of through holes and the second transverse side is half the longitudinal length of the first longitudinal side.

[0018] Unlike prior art, the backlight device of the present invention not only emits light more uniformly, but also has the advantages of saving power and low cost, especially the low manufacturing cost of the flexible circuit board used in it.

[0019] The advantages and spirit of the present invention can be further understood from the following detailed description of the invention and the accompanying drawings.

Implementation Method

[0020] Please refer to Figures 2, 3, 4, and 5. These figures schematically depict a backlight device 2 according to a first preferred embodiment of the present invention. Figure 2 is a top view schematically illustrating the light-emitting device 2 according to a first preferred embodiment of the present invention. Figure 3 is a cross-sectional view of the backlight device 2 in Figure 2 along line AA. Figure 4 is a top view schematically illustrating the essential elements of the light-emitting device 2 according to the first preferred embodiment of the present invention—a strip-shaped flexible circuit board 22, a plurality of first light-emitting elements 24, a plurality of second light-emitting elements 26, and a plurality of third light-emitting elements 28, with the strip-shaped flexible circuit board 22 in an unbent state. Figure 5 is another top view schematically illustrating the essential elements of the light-emitting device 2 according to the first preferred embodiment of the present invention—a strip-shaped flexible circuit board 22, a plurality of first light-emitting elements 24, a plurality of second light-emitting elements 26, and a plurality of third light-emitting elements 28, with the strip-shaped flexible circuit board 22 in a bent state. The backlight device 2 according to a first preferred embodiment of the present invention is used for an illuminated keyboard.

[0021] As shown in Figures 2 and 3, the backlight device 2 according to the first preferred embodiment of the present invention includes a light guide plate 20, a strip-shaped flexible circuit board 22, a plurality of first light-emitting elements 24, a plurality of second light-emitting elements 26 and a plurality of third light-emitting elements 28.

[0022] The light guide plate 20 defines a longitudinal direction L and a transverse direction T. Furthermore, the light guide plate 20 has a top surface 201, a back surface 202 opposite to the top surface 201, a first transverse side 203, a second transverse side 204 opposite to the first transverse side 203, a first longitudinal side 205, a second longitudinal side 206 opposite to the first longitudinal side 205, a plurality of first through holes 207, a plurality of second through holes 208, and a plurality of third through holes 209. The plurality of first through holes 207 are arranged from the first transverse side 203 along the longitudinal direction L and are close to the first longitudinal side 205. The plurality of second through holes 208 are arranged from the first transverse side 203 along the longitudinal direction L and are close to the second longitudinal side 206. A plurality of third through-holes 209 are arranged adjacent to the second lateral side 204 and along the lateral direction T, and are located between a plurality of first through-holes 207 and a plurality of second through-holes 208. Each first through-hole 207 has its own first light-incident surface 2072. The plurality of first light-incident surfaces 2072 of the plurality of first through-holes 207 alternately face the second longitudinal side 206 and the first longitudinal side 205. Each second through-hole 208 has its own second light-incident surface 2082. The plurality of second light-incident surfaces 2082 of the plurality of second through-holes 208 alternately face the first longitudinal side 205 and the second longitudinal side 206. Each third through-hole 209 has its own third light-incident surface 2092. The plurality of third light-incident surfaces 2092 of the plurality of third through-holes 209 face the first lateral side 203.

[0023] As shown in Figures 4 and 5, the elongated flexible circuit board 22 includes a first elongated portion 221, a first bent portion 222 connecting the first elongated portion 221, a second elongated portion 223 connecting the first bent portion 222, a second bent portion 224 connecting the second elongated portion 223, and a third elongated portion 225 connecting the second bent portion 224. The first elongated portion 221 has a first upper surface 2212 and a first lower surface 2214, and defines a first length direction S1. The second elongated portion 223 has a second upper surface 2232 and a second lower surface 2234, and defines a second length direction S2. The third elongated portion 225 has a third upper surface 2252 and a third lower surface 2254, and defines a third length direction S3.

[0024] As also shown in Figures 4 and 5, a plurality of first light-emitting elements 24 are electrically bonded to the first lower surface 2214 of the first elongated portion 221 and arranged along the first length direction S1. Each first light-emitting element 24 corresponds to a first through hole 207. The light-emitting direction of each first light-emitting element 24 is the same as the orientation of the first light-incident surface 2072 of its corresponding first through hole 207. A plurality of second light-emitting elements 26 are electrically bonded to the third lower surface 2254 of the third elongated portion 225 and arranged along the third length direction S3. Each second light-emitting element 26 corresponds to a second through hole 208. The light-emitting direction of each second light-emitting element 26 is the same as the orientation of the second light-incident surface 2082 of its corresponding second through hole 208. A plurality of third light-emitting elements 28 are electrically bonded to the second upper surface 2232 of the second elongated portion 223 and arranged along the second length direction S2. Each third light-emitting element 28 corresponds to a third through hole 209. The light emission direction of each third light-emitting element 28 is the same as the orientation of the third light-incident surface 2092 of its corresponding third through-hole 209. By using light-emitting elements with different orientations and through-holes with different orientations of light-incident surfaces on the light guide plate 20, the backlight device 2 of the first preferred embodiment of the present invention emits light more uniformly.

[0025] The first bending portion 222 and the second bending portion 224 are bent so that the first lower surface 2214 of the first elongated portion 221, the third lower surface 2254 of the third elongated portion 225, and the second upper surface 2232 of the second elongated portion 223 are coplanar, as shown in Figure 5. The elongated flexible circuit board 22 is placed on the back surface 202 of the light guide plate 20 with the first lower surface 2214, the second upper surface 2232, and the third lower surface 2254, so that each first light-emitting element 24 is placed in its corresponding first through hole 207, each second light-emitting element 26 is placed in its corresponding second through hole 208, and each third light-emitting element 28 is placed in its corresponding third through hole 209, as shown in Figure 2. It should be noted that the top view of the elongated flexible circuit board 22 shown in Figure 5 presents a U-shape. If the elongated flexible circuit board 22 is directly cut into a U-shaped circuit board, the manufacturing process of this type of circuit board consumes a lot of materials and has extremely high manufacturing costs. Obviously, the backlight device 2 of the first preferred embodiment of the present invention has a lower manufacturing cost by forming a long strip flexible circuit board 22 with a U-shape in top view by bending the first bending portion 222 and the second bending portion 224.

[0026] Each first light-emitting element 24 emits a first light beam that strikes the first light-incident surface 2072 of its corresponding first through-hole 207, and then enters the light guide plate 20. Each second light-emitting element 26 emits a second light beam that strikes the second light-incident surface 2082 of its corresponding second through-hole 208, and then enters the light guide plate 20. Each third light-emitting element 28 emits a third light beam that strikes the third light-incident surface 2092 of its corresponding third through-hole 209, and then enters the light guide plate 20. Thus, the backlight device 2 according to the first preferred embodiment of the present invention, through the U-shaped elongated flexible circuit board 22 and the through-holes on the light guide plate 20 with different orientations of the light-incident surfaces, makes the backlight device 2 emit light more uniformly and has advantages such as power saving and low cost.

[0027] In one specific embodiment, each of the first light-emitting element 24, each of the second light-emitting element 26 and each of the third light-emitting element 28 may be a light-emitting diode.

[0028] In a specific embodiment, as also shown in FIG2, the first distance d1 between the plurality of first through holes 207 and the first longitudinal side 205 and the second distance d2 between the plurality of second through holes 208 and the second longitudinal side 206 are one-fifth to one-half of the lateral length X of the first lateral side 203.

[0029] Further, as shown in Figures 4 and 5, the backlight device 2 according to the first preferred embodiment of the present invention also includes a connecting flexible circuit board 29. The connecting flexible circuit board 29 includes a third bent portion 291 and a fourth elongated portion 292. The third bent portion 291 is connected to the leading edge 2236 of the second elongated portion 223. The fourth elongated portion 292 is connected to the third bent portion 291. In practical applications, the third bent portion 291 is bent so that a portion of the fourth elongated portion 292 is in close contact with the second lower surface 2234 of the second elongated portion 223. It should be noted that the fourth elongated portion 292 of the backlight device 2 according to the first preferred embodiment of the present invention is also elongated, so that the connecting flexible circuit board 29 and the elongated flexible circuit board 22 are molded together, which can also achieve the purpose of less material consumption, thereby reducing the manufacturing cost of the connecting flexible circuit board 29 and the elongated flexible circuit board 22.

[0030] Please refer to Figures 6, 7, 8, and 9. These figures schematically depict a backlight device 3 according to a second preferred embodiment of the present invention. Figure 6 is a top view schematically illustrating the light-emitting device 3 according to a second preferred embodiment of the present invention. Figure 7 is a cross-sectional view of the backlight device 3 in Figure 6 along line BB. Figure 8 is a top view schematically illustrating the essential elements of the light-emitting device 3 according to a second preferred embodiment of the present invention—a strip-shaped flexible circuit board 32, a plurality of first light-emitting elements 34, a plurality of second light-emitting elements 36, and a plurality of third light-emitting elements 38, with the strip-shaped flexible circuit board 32 in an unbent state. Figure 9 is another top view schematically illustrating the essential elements of the light-emitting device 3 according to a second preferred embodiment of the present invention—a strip-shaped flexible circuit board 32, a plurality of first light-emitting elements 34, a plurality of second light-emitting elements 36, and a plurality of third light-emitting elements 38, with the strip-shaped flexible circuit board 32 in a bent state. According to a second preferred embodiment of the present invention, the backlight device 3 is used for a backlit keyboard.

[0031] As shown in Figures 6 and 7, the backlight device 3 according to the second preferred embodiment of the present invention includes a light guide plate 30, a strip-shaped flexible circuit board 32, a plurality of first light-emitting elements 34, a plurality of second light-emitting elements 36, and a plurality of third light-emitting elements 38.

[0032] The light guide plate 30 defines a longitudinal direction L and a transverse direction T. The light guide plate 30 also has a top surface 301, a back surface 302 opposite to the top surface 301, a first transverse side 303, a second transverse side 304 opposite to the first transverse side 303, a first longitudinal side 305, a second longitudinal side 306 opposite to the first longitudinal side 305, a plurality of first through holes 307, a plurality of second through holes 308, and a plurality of third through holes 309. The plurality of first through holes 307 are arranged from the first transverse side 303 along the longitudinal direction L and are close to the first longitudinal side 305. The plurality of second through holes 308 are arranged from the first transverse side 303 along the longitudinal direction L and are close to the second longitudinal side 306. The plurality of third through holes 309 are arranged along the transverse direction T and are located between the plurality of first through holes 307 and the plurality of second through holes 308 and are close to the second transverse side 304. Each first through-hole 307 has its own first light-incident surface 3072. The plurality of first light-incident surfaces 3072 of the plurality of first through-holes 307 alternately face the second longitudinal side 306 and the first longitudinal side 305. Each second through-hole 308 has its own second light-incident surface 3082. The plurality of second light-incident surfaces 3082 of the plurality of second through-holes 308 alternately face the first longitudinal side 305 and the second longitudinal side 306. Each third through-hole 309 has its own third light-incident surface 3092. The plurality of third light-incident surfaces 3092 of the plurality of third through-holes 309 alternately face the first transverse side 303 and the second transverse side 304.

[0033] As shown in Figures 8 and 9, the elongated flexible circuit board 32 includes a first elongated portion 321, a first bent portion 322 connecting the first elongated portion 321, a second elongated portion 323 connecting the first bent portion 322, a second bent portion 324 connecting the second elongated portion 323, and a third elongated portion 325 connecting the second bent portion 324. The first elongated portion 321 has a first upper surface 3212 and a first lower surface 3214, and defines a first length direction S1. The second elongated portion 323 has a second upper surface 3232 and a second lower surface 3234, and defines a second length direction S2. The third elongated portion 325 has a third upper surface 3252 and a third lower surface 3254, and defines a third length direction S3.

[0034] As also shown in Figures 8 and 9, a plurality of first light-emitting elements 34 are electrically bonded to the first lower surface 3214 of the first elongated portion 321 and arranged along the first length direction S1. Each first light-emitting element 34 corresponds to a first through hole 307. The light-emitting direction of each first light-emitting element 34 is the same as the orientation of the first light-incident surface 3072 of its corresponding first through hole 307. A plurality of second light-emitting elements 36 are electrically bonded to the third lower surface 3254 of the third elongated portion 325 and arranged along the third length direction S3. Each second light-emitting element 36 corresponds to a second through hole 308. The light-emitting direction of each second light-emitting element 36 is the same as the orientation of the second light-incident surface 3082 of its corresponding second through hole 308. A plurality of third light-emitting elements 38 are electrically bonded to the second upper surface 3232 of the second elongated portion 323 and arranged along the second length direction S2. Each third light-emitting element 38 corresponds to a third through hole 309. The light emission direction of each third light-emitting element 38 is the same as the orientation of the third light-incident surface 3092 of its corresponding third through-hole 309. By using light-emitting elements with different orientations and through-holes with different orientations on the light guide plate 30, the backlight device 3 of the second preferred embodiment of the present invention emits light more uniformly.

[0035] The first bending portion 322 and the second bending portion 324 are bent so that the first lower surface 3214 of the first elongated portion 321, the third lower surface 3254 of the third elongated portion 325, and the second upper surface 3232 of the second elongated portion 323 are coplanar, as shown in Figure 9. The elongated flexible circuit board 32 is placed on the back surface 302 of the light guide plate 30 with the first lower surface 3214, the second upper surface 3232, and the third lower surface 3254, so that each first light-emitting element 34 is placed in its corresponding first through hole 307, each second light-emitting element 36 is placed in its corresponding second through hole 308, and each third light-emitting element 38 is placed in its corresponding third through hole 309, as shown in Figure 7. It should be noted that the top view of the elongated flexible circuit board 32 shown in Figure 9 presents a U-shape. If the elongated flexible circuit board 32 is directly cut into a U-shaped circuit board, the manufacturing process of this type of circuit board consumes a lot of materials and has extremely high manufacturing costs. Obviously, the backlight device 3 of the first preferred embodiment of the present invention has a lower manufacturing cost by forming a long strip flexible circuit board 32 in the form of a U-shape in top view by bending the first bending portion 322 and the second bending portion 324.

[0036] Each first light-emitting element 34 emits a first light beam that strikes the first light-incident surface 3072 of its corresponding first through-hole 307, and then enters the light guide plate 30. Each second light-emitting element 36 emits a second light beam that strikes the second light-incident surface 3082 of its corresponding second through-hole 308, and then enters the light guide plate 30. Each third light-emitting element 38 emits a third light beam that strikes the third light-incident surface 3092 of its corresponding third through-hole 309, and then enters the light guide plate 30. Thus, the second backlight device 3 according to the present invention, through the U-shaped strip-shaped flexible circuit board 32 formed by bending and the through-holes on the light guide plate 30 with different orientations of the light-incident surfaces, makes the backlight device 3 emit light more uniformly and has advantages such as power saving and low cost.

[0037] In one specific embodiment, each of the first light-emitting element 34, each of the second light-emitting element 36 and each of the third light-emitting element 38 may be a light-emitting diode.

[0038] In one specific embodiment, as also shown in FIG6, at least one first light-incident surface 3072 of the first through hole 307 closest to the second lateral side 304 faces the first longitudinal side 305 adjacent to the second lateral side 304. At least one third light-incident surface 3092 of the third through hole 309 closest to the first longitudinal side 305 faces the second lateral side 304 adjacent to the first longitudinal side 305. At least one third light-incident surface 3092 of the third through hole 309 closest to the second longitudinal side 306 faces the second lateral side 304 adjacent to the second longitudinal side 306. At least one second light-incident surface 3082 of the second through hole 308 closest to the second lateral side 304 faces the second longitudinal side 306 adjacent to the second lateral side 304. Therefore, the backlight device 3 of the preferred embodiment of the present invention emits light more uniformly.

[0039] In a specific embodiment, as shown in FIG6, the first distance d1 between the plurality of first through holes 307 and the first longitudinal side 305 and the second distance d2 between the plurality of second through holes 308 and the second longitudinal side 306 are one-fifth to one-half of the lateral length X of the first lateral side 303.

[0040] In one specific embodiment, as shown in FIG6, the third distance d3 between the plurality of third through holes 309 and the second transverse side 304 is one-fifth to one-half of the longitudinal length Y of the first longitudinal side 305.

[0041] Further, as shown in Figures 8 and 9, the backlight device 3 according to the second preferred embodiment of the present invention also includes a connecting flexible circuit board 39. The connecting flexible circuit board 39 includes a third bent portion 391 and a fourth elongated portion 392. The third bent portion 391 is connected to the leading edge 3236 of the second elongated portion 323. The fourth elongated portion 392 is connected to the third bent portion 391. In practical applications, the third bent portion 391 is bent so that a portion of the fourth elongated portion 392 is in close contact with the second lower surface 3234 of the second elongated portion 323. It should be noted that the fourth elongated portion 392 of the backlight device 3 according to the second preferred embodiment of the present invention is also elongated, so that the connecting flexible circuit board 39 and the elongated flexible circuit board 32 can be molded together to achieve the purpose of less material consumption, thereby reducing the manufacturing cost of the connecting flexible circuit board 39 and the elongated flexible circuit board 32.

[0042] Please refer to Figures 10, 11, 12, and 13. These figures schematically depict a backlight device 4 according to a third preferred embodiment of the present invention. Figure 10 is a top view schematically illustrating the light-emitting device 4 according to a third preferred embodiment of the present invention. Figure 11 is a cross-sectional view of the backlight device 4 in Figure 10 along line CC. Figure 12 is a top view schematically illustrating essential elements of the light-emitting device 4 according to a third preferred embodiment of the present invention—a strip-shaped flexible circuit board 42 and a plurality of light-emitting elements 44, with the strip-shaped flexible circuit board 42 in an unbent state. Figure 13 is another top view schematically illustrating essential elements of the light-emitting device 4 according to a third preferred embodiment of the present invention—a strip-shaped flexible circuit board 42 and a plurality of light-emitting elements 44, with the strip-shaped flexible circuit board 42 in a bent state. The backlight device 4 according to the third preferred embodiment of the present invention is used for a backlit keyboard.

[0043] As shown in Figures 10 and 11, the backlight device 4 according to the third preferred embodiment of the present invention includes a light guide plate 40, a strip-shaped flexible circuit board 42, and a plurality of light-emitting elements 44.

[0044] The light guide plate 40 defines a longitudinal direction L and a transverse direction T. The light guide plate 40 also has a top surface 401, a back surface 402 opposite to the top surface 401, a first transverse side 403, a second transverse side 404 opposite to the first transverse side 403, a first longitudinal side 405, a second longitudinal side 406 opposite to the first longitudinal side 405, and a plurality of through holes 407. The plurality of through holes 407 are arranged along the transverse direction T and are located between the first longitudinal side 405 and the second longitudinal side 406. Each through hole 407 has its own light-incident surface 4072. The plurality of light-incident surfaces 4072 of the plurality of through holes 407 are alternately oriented toward the first transverse side 403 and the second transverse side 404.

[0045] As shown in Figures 12 and 13, the elongated flexible circuit board 42 has an upper surface 422 and a lower surface 424 (shown in Figure 11), and defines a length direction S4. A plurality of light-emitting elements 44 are electrically bonded to the upper surface 422 of the elongated flexible circuit board 42 and arranged along the length direction S4. Each light-emitting element 44 corresponds to a through hole 407. The light-emitting direction of each light-emitting element 44 is the same as the orientation of the light-incident surface 4072 of its corresponding through hole 407. The elongated flexible circuit board 42 is placed on the back surface 402 of the light guide plate 40 with its upper surface 422, such that each light-emitting element 44 is placed in its corresponding through hole 407, as shown in Figure 11. Each light-emitting element 44 emits light towards the light-incident surface 4072 of its corresponding through hole 407, and then into the light guide plate 40. Thus, the third backlight device 4 according to the present invention emits light more uniformly and has advantages such as power saving and low cost.

[0046] In one specific embodiment, each light-emitting element 44 may be a light-emitting diode.

[0047] In one specific embodiment, the distance d4 between the plurality of through holes 407 and the second transverse side 404 is half of the longitudinal length Y of the first longitudinal side 405.

[0048] Further, as also shown in Figures 12 and 13, the backlight device 4 according to the third preferred embodiment of the present invention further includes a connecting flexible circuit board 46. The connecting flexible circuit board 46 includes a bent portion 461 and an elongated portion 462. The bent portion 461 is connected to the leading edge 426 of the elongated flexible circuit board 42. The elongated portion 462 is connected to the bent portion 461. The bent portion 461 is bent so that a portion of the elongated portion 462 is in close contact with the lower surface 424 of the elongated flexible circuit board 42. It should be noted that the elongated portion 462 of the backlight device 4 according to the third preferred embodiment of the present invention is also elongated. Molding the connecting flexible circuit board 46 and the elongated flexible circuit board 42 together can also achieve the purpose of low material consumption, thereby reducing the manufacturing cost of the connecting flexible circuit board 46 and the elongated flexible circuit board 42.

[0049] Based on the backlit keyboard of a notebook computer, one example of the present invention uses the backlight device 2 of the first preferred embodiment of the present invention as its architecture, employing a light guide plate with a thickness of 0.25 mm and 29 LEDs with a thickness of 0.4 mm. The voltage and current of the example of the present invention are listed in Table 1. For comparison, Comparative Example 1 uses the backlight device 1 shown in FIG. 1 as its architecture, also employing a light guide plate with a thickness of 0.25 mm and 15 LEDs with a thickness of 0.4 mm, and its voltage and current are also listed in Table 1. Similarly, for comparison, Comparative Example 2 uses a backlight device employing sub-millimeter light-emitting diodes as its architecture, also employing a light guide plate with a thickness of 0.25 mm and 95 mini-LEDs, and its power consumption is also listed in Table 1.

[0050] Table 1 project Electrical characteristics Comparative Example 1 Comparison 2 Examples of the present invention Voltage 5V 5V 5V Current required for an average brightness of 30 nits 300 mA 180 mA 210 mA Current required for an average brightness of 15 nits 140 mA 100 mA 110 mA

[0051] According to Table 1, the power consumption of the example of the present invention, Comparative Example 1, and Comparative Example 2 can be clearly calculated. Based on the power consumption of Comparative Example 1, Comparative Example 2 saves 28% to 40% of power, while the example of the present invention saves 21% to 30% of power. Although Comparative Example 2 is more power-efficient, its architecture has a higher manufacturing cost. The example of the present invention also has considerable power efficiency, and its architecture has a lower manufacturing cost.

[0052] Through the above detailed description of the present invention, it can be clearly understood that the backlight device according to the present invention not only emits light more uniformly, but also has the advantages of saving power and low cost, especially the low manufacturing cost of the flexible circuit board used in it.

[0053] The detailed description of the preferred embodiments above is intended to more clearly describe the features and spirit of the present invention, and is not intended to limit the scope of the present invention with the preferred embodiments disclosed above. Rather, the aim is to cover various changes and equivalent arrangements within the scope of the patent claims of the present invention. Therefore, the scope of the patent claims of the present invention should be interpreted in the broadest possible sense based on the foregoing description, so as to cover all possible changes and equivalent arrangements. [Simplified Explanation of the Diagram]

[0054] Figure 1 is a top view of a prior art backlight device. Figure 2 is a top view of a backlight device according to a first preferred embodiment of the present invention. Figure 3 is a cross-sectional view of the backlight device in Figure 2 along line AA. Figure 4 is a top view of the essential components of the backlight device according to the first preferred embodiment of the present invention—a strip-shaped flexible circuit board, a plurality of first light-emitting elements, a plurality of second light-emitting elements, and a plurality of third light-emitting elements, with the strip-shaped flexible circuit board in an unbent state. Figure 5 is a top view of the essential components of the backlight device according to the first preferred embodiment of the present invention—a strip-shaped flexible circuit board, a plurality of first light-emitting elements, a plurality of second light-emitting elements, and a plurality of third light-emitting elements, with the strip-shaped flexible circuit board in a bent state. Figure 6 is a top view of a backlight device according to a second preferred embodiment of the present invention. Figure 7 is a cross-sectional view of the backlight device in Figure 6 along line BB. Figure 8 is a top view of the backlight device according to the second preferred embodiment of the present invention, showing the essential components—a strip-shaped flexible circuit board, a plurality of first light-emitting elements, a plurality of second light-emitting elements, and a plurality of third light-emitting elements—with the strip-shaped flexible circuit board in an unbent state. Figure 9 is a top view of the backlight device according to the second preferred embodiment of the present invention, showing the essential components—a strip-shaped flexible circuit board, a plurality of first light-emitting elements, a plurality of second light-emitting elements, and a plurality of third light-emitting elements—with the strip-shaped flexible circuit board in a bent state. Figure 10 is a top view of the backlight device according to the third preferred embodiment of the present invention. Figure 11 is a cross-sectional view of the backlight device in Figure 10 along line CC. Figure 12 is a top view of the backlight device according to the third preferred embodiment of the present invention, showing the essential components—a strip-shaped flexible circuit board and a plurality of light-emitting elements—with the strip-shaped flexible circuit board in an unbent state. Figure 13 is a top view of the essential components of the backlight device of the third preferred embodiment of the present invention—a long strip of flexible circuit board and a plurality of light-emitting elements, with the long strip of flexible circuit board in a bent state.

Claims

1. A backlight device for an illuminated keyboard, comprising: a light guide plate defining a longitudinal direction and a transverse direction and having a top surface, a back surface opposite to the top surface, a first transverse side, a second transverse side opposite to the first transverse side, a first longitudinal side, a second longitudinal side opposite to the first longitudinal side, a plurality of first through holes, a plurality of second through holes, and a plurality of third through holes, wherein the plurality of first through holes are arranged from the first transverse side along the longitudinal direction and close to the first longitudinal side, the plurality of second through holes are arranged from the first transverse side along the longitudinal direction and close to the second longitudinal side, and the plurality of third through holes are adjacent to the second transverse side and along the transverse direction. Arranged in a directional direction and located between the plurality of first through holes and the plurality of second through holes, each first through hole has its own first light-incident surface. Among the plurality of first light-incident surfaces of the plurality of first through holes, one of two adjacent first light-incident surfaces along the longitudinal direction faces the second longitudinal side, and the other first light-incident surface faces the first longitudinal side. Each second through hole has its own second light-incident surface. Among the plurality of second light-incident surfaces of the plurality of second through holes, one of two adjacent second light-incident surfaces along the longitudinal direction faces the first longitudinal side, and the other second light-incident surface faces the second longitudinal side. Each of the third through holes has its own third light-incident surface, and the plurality of third light-incident surfaces of the plurality of third through holes face the first lateral side; a long strip-shaped flexible circuit board includes a first long strip portion, a first bent portion connecting the first long strip portion, a second long strip portion connecting the first bent portion, a second bent portion connecting the second long strip portion, and a third long strip portion connecting the second bent portion. The first long strip portion has a first upper surface and a first lower surface and defines a first length direction. The second long strip portion has a second upper surface and a second lower surface and defines a second length direction. The third long strip portion has... The device has a third upper surface and a third lower surface, defining a third length direction; a plurality of first light-emitting elements electrically bonded to the first lower surface of the first elongated portion and arranged along the first length direction, each first light-emitting element corresponding to a first through hole; a plurality of second light-emitting elements electrically bonded to the third lower surface of the third elongated portion and arranged along the third length direction, each second light-emitting element corresponding to a second through hole; and a plurality of third light-emitting elements electrically bonded to the second upper surface of the second elongated portion and arranged along the second length direction, each third light-emitting element corresponding to a third through hole;The first and second bending portions are bent such that the first lower surface of the first elongated portion and the third lower surface of the third elongated portion are flipped upwards, thus facing the same side and sharing a plane with the second upper surface of the still upward-facing second elongated portion. The elongated flexible circuit board is placed on the back side of the light guide plate with the first lower surface, the second upper surface, and the third lower surface, so that each first light-emitting element is placed in its corresponding first through hole, each second light-emitting element is placed in its corresponding second through hole, and each third light-emitting element is placed in its corresponding third through hole. Each first light-emitting element emits a first ray that strikes the first light-incident surface of its corresponding first through hole and then enters the light guide plate. Each second light-emitting element emits a second ray that strikes the second light-incident surface of its corresponding second through hole and then enters the light guide plate. Each third light-emitting element emits a third ray that strikes the third light-incident surface of its corresponding third through hole and then enters the light guide plate.

2. The backlight device as claimed in claim 1, wherein a first distance between the plurality of first through holes and the first longitudinal side and a second distance between the plurality of second through holes and the second longitudinal side are one-fifth to one-half of the lateral length of the first lateral side.

3. The backlight device as claimed in claim 1 further includes a connecting flexible circuit board, including a third bend and a fourth elongated portion, the third bend being connected to a leading edge of the second elongated portion, the fourth elongated portion being connected to the third bend, wherein the third bend is bent such that a portion of the fourth elongated portion is in close contact with the second lower surface of the second elongated portion.

4. A backlight device for an illuminated keyboard, comprising: a light guide plate defining a longitudinal direction and a transverse direction and having a top surface, a back surface opposite to the top surface, a first transverse side, a second transverse side opposite to the first transverse side, a first longitudinal side, a second longitudinal side opposite to the first longitudinal side, a plurality of first through holes, a plurality of second through holes, and a plurality of third through holes, wherein the plurality of first through holes are arranged from the first transverse side along the longitudinal direction and close to the first longitudinal side, the plurality of second through holes are arranged from the first transverse side along the longitudinal direction and close to the second longitudinal side, and the plurality of third through holes... The plurality of through holes are arranged along the transverse direction and located between the plurality of first through holes and the plurality of second through holes, and close to the second transverse side. Each first through hole has its own first light-incident surface, and the plurality of first light-incident surfaces of the plurality of first through holes alternately face the second longitudinal side and the first longitudinal side. Each second through hole has its own second light-incident surface, and the plurality of second light-incident surfaces of the plurality of second through holes alternately face the first longitudinal side and the second longitudinal side. Each third through hole has its own third light-incident surface, and the plurality of third light-incident surfaces of the plurality of third through holes... The smooth surfaces alternately face the first lateral side and the second lateral side; a long strip-shaped flexible circuit board includes a first long strip portion, a first bent portion connecting the first long strip portion, a second long strip portion connecting the first bent portion, a second bent portion connecting the second long strip portion, and a third long strip portion connecting the second bent portion. The first long strip portion has a first upper surface and a first lower surface and defines a first length direction. The second long strip portion has a second upper surface and a second lower surface and defines a second length direction. The third long strip portion has a third upper surface and a third lower surface. The surface is defined by a third length direction; a plurality of first light-emitting elements are electrically bonded to the first lower surface of the first elongated portion and arranged along the first length direction, each first light-emitting element corresponding to a first through hole; a plurality of second light-emitting elements are electrically bonded to the third lower surface of the third elongated portion and arranged along the third length direction, each second light-emitting element corresponding to a second through hole; and a plurality of third light-emitting elements are electrically bonded to the second upper surface of the second elongated portion and arranged along the second length direction, each third light-emitting element corresponding to a third through hole;The first and second bending portions are bent such that the first lower surface of the first elongated portion, the third lower surface of the third elongated portion, and the second upper surface of the second elongated portion share a common plane. The elongated flexible circuit board is placed on the back side of the light guide plate with its first lower surface, second upper surface, and third lower surface on the back side. This results in each first light-emitting element being placed in its corresponding first through-hole, each second light-emitting element being placed in its corresponding second through-hole, and each third light-emitting element being placed in its corresponding third through-hole. Each first light-emitting element emits a first ray that strikes the first light-incident surface of its corresponding first through-hole and then enters the light guide plate. Each second light-emitting element emits a second ray that strikes the second light-incident surface of its corresponding second through-hole and then enters the light guide plate. Each third light-emitting element emits a third ray that strikes the third light-incident surface of its corresponding third through-hole and then enters the light guide plate.

5. The backlight device as claimed in claim 4, wherein the first light-incident surface of the first through-hole closest to the second lateral side faces the first longitudinal side and is adjacent to the second lateral side; the third light-incident surface of the third through-hole closest to the first longitudinal side faces the second lateral side and is adjacent to the first longitudinal side; the third light-incident surface of the third through-hole closest to the second longitudinal side faces the second lateral side and is adjacent to the second longitudinal side; and the second light-incident surface of the second through-hole closest to the second lateral side faces the second longitudinal side and is adjacent to the second lateral side.

6. The backlight device as claimed in claim 4, wherein a first distance between the plurality of first through holes and the first longitudinal side and a second distance between the plurality of second through holes and the second longitudinal side are one-fifth to one-half of the lateral length of the first lateral side.

7. The backlight device as claimed in claim 4, wherein a third distance between the plurality of third through holes and the second transverse side is one-fifth to one-half of the longitudinal length of the first longitudinal side.

8. The backlight device as claimed in claim 4 further includes a connecting flexible circuit board, including a third bend and a fourth elongated portion, the third bend being connected to a leading edge of the second elongated portion, the fourth elongated portion being connected to the third bend, wherein the third bend is bent such that a portion of the fourth elongated portion is in close contact with the second lower surface of the second elongated portion.

9. A backlight device for an illuminated keyboard, comprising: a light guide plate defining a longitudinal direction and a transverse direction and having a top surface, a back surface opposite to the top surface, a first transverse side, a second transverse side opposite to the first transverse side, a first longitudinal side, a second longitudinal side opposite to the first longitudinal side, and a plurality of through holes, the plurality of through holes being arranged along the transverse direction and located between the first longitudinal side and the second longitudinal side, each through hole having a respective light-incident surface, the plurality of light-incident surfaces of the plurality of through holes alternately facing the first transverse side and the second longitudinal side. The second lateral side; a long strip of flexible circuit board having an upper surface and a lower surface and defining a length direction; and a plurality of light-emitting elements electrically bonded to the upper surface of the long strip of flexible circuit board and arranged along the length direction, each first light-emitting element corresponding to a through hole; wherein the long strip of flexible circuit board is placed on the back side of the light guide plate with the upper surface thereon, such that each light-emitting element is placed in its corresponding through hole, and each light-emitting element emits a light that is directed toward the light-incident surface of its corresponding through hole and then into the light guide plate.

10. The backlight device as claimed in claim 9, wherein one of the distances between the plurality of through holes and the second lateral side is half the longitudinal length of one of the first longitudinal side.

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