Light-emitting keyboard and backlighting device for a light-emitting keyboard

Abstract

The present application discloses a light-emitting keyboard and a backlight device for the light-emitting keyboard. The backlight device comprises a light guide plate, a circuit board and a plurality of light-emitting elements. The light guide plate has a plurality of through holes. The plurality of light-emitting elements are electrically connected to the circuit board. Each light-emitting element corresponds to a through hole. The circuit board is disposed on the back of the light guide plate, so that each light-emitting element is located in its corresponding through hole, and the light-emitting side of each light-emitting element faces the light-incident surface of its corresponding through hole. Each light-emitting element emits light from its light-emitting side to the light-incident surface of its corresponding through hole and then into the light guide plate. The light-incident surface of a specific through hole among the plurality of through holes has an optical adjustment surface, and the optical adjustment surface has a curved central axis coaxial with the central optical axis of its corresponding light-emitting element. The backlight device for the light-emitting keyboard according to the present application effectively utilizes the energy of the light emitted by the light-emitting elements, and the brightness of the patterns on the keycaps of the light-emitting keyboard according to the present application is uniform.

Description

TECHNICAL FIELD

[0001] The present invention relates to a light-emitting keyboard and a backlight device for a light-emitting keyboard, and in particular to a backlight device capable of adjusting the beam angle of light emitted by light-emitting elements into a light guide plate. BACKGROUND

[0002] Light-emitting keyboards are common input peripheral devices on the market. Most of the current light-emitting keyboards use a backlight device.

[0003] The backlight device for a light-emitting keyboard of the prior art comprises a light guide plate and a plurality of light-emitting elements. The light guide plate has a plurality of through-holes. Each light-emitting element is disposed in a corresponding through-hole, and the light-emitting side of each light-emitting element faces the light-incident surface of the corresponding through-hole. Each light-emitting element emits light from the light-emitting side toward the light-incident surface of the corresponding through-hole and into the light guide plate. It should be emphasized that the light-incident surfaces of the plurality of through-holes of the backlight device of the prior art are all flat surfaces, resulting in a fixed beam angle of the light emitted by the light-emitting elements into the light guide plate.

[0004] However, the light guide plate of the backlight device of the prior art also has a plurality of break holes formed to match the assembly of the light-emitting keyboard. The arrangement design of the plurality of light-emitting elements of the backlight device of the prior art can encounter a situation where the distance between two adjacent break holes in the travel path of the emitted light in the light guide plate is close, resulting in illumination shadow behind the break holes and ineffective use of the energy of the light emitted by the light-emitting elements.

[0005] In addition, the backlight device of the prior art cannot increase the number of light-emitting elements due to the limitations of the mechanism or the circuit board used to electrically connect the plurality of light-emitting elements, resulting in uneven brightness of the patterns on the keycaps of the light-emitting keyboard. SUMMARY

[0006] Therefore, the technical problem to be solved by the present invention is to provide a backlight device for a light-emitting keyboard capable of adjusting the beam angle of light emitted by light-emitting elements into a light guide plate and a light-emitting keyboard using the backlight device.

[0007] The backlight device according to a preferred embodiment of the present application is used for a light-emitting keyboard. The backlight device according to a preferred embodiment of the present application comprises a light guide plate, a circuit board and a plurality of light-emitting elements. The light guide plate has a top surface, a back surface and a plurality of through holes. Each of the through holes has an entrance surface. The plurality of light-emitting elements are electrically connected to the circuit board. Each of the light-emitting elements has a light-emitting side and a central optical axis, and each of the light-emitting elements corresponds to one of the through holes. The circuit board is disposed on the back surface of the light guide plate, such that each of the light-emitting elements is disposed in the corresponding through hole, and the light-emitting side of each of the light-emitting elements faces the entrance surface of the corresponding through hole. Each of the light-emitting elements emits light from the light-emitting side thereof toward the entrance surface of the corresponding through hole, and the light is then emitted into the light guide plate. The plurality of through holes comprises at least one first through hole, and the entrance surface of each of the first through holes has a first optical adjustment surface. The first optical adjustment surface can be one of a first concave spherical surface, a first convex spherical surface, a first concave aspherical surface, a first convex aspherical surface, a first Fresnel concave arc surface, a first Fresnel convex arc surface, or any combination thereof. The first optical adjustment surface has a first curved central axis coaxial with the central optical axis of the corresponding light-emitting element.

[0008] In an embodiment, the first shortest distance between the first optical adjustment surface of the first through hole and the light-emitting side of the corresponding light-emitting element ranges from 0.04 mm to 0.12 mm.

[0009] In an embodiment, the light guide plate further has a first broken hole. The first broken hole is located on a first original optical path of the light emitted from the entrance surface of the first through hole into the light guide plate. A first adjusted optical path of the light adjusted by the first optical adjustment surface of the first through hole and then emitted into the light guide plate does not pass through the first broken hole, wherein the first original optical path refers to a path of a light beam on a boundary of the light beam emitted into the entrance surface of the first through hole, which is a flat surface and has no first optical adjustment surface thereon.

[0010] In an embodiment, the light guide plate further has a second broken hole. The second broken hole is located on a second original optical path of the light emitted from the entrance surface of the first through hole into the light guide plate. A second adjusted optical path of the light adjusted by the first optical adjustment surface of the first through hole and then emitted into the light guide plate does not pass through the second broken hole. The first adjusted optical path and the second adjusted optical path are located between the first broken hole and the second broken hole.

[0011] According to a variation of the backlight device of the present application, the plurality of through holes further comprises at least one second through hole, each of the second through holes has a recess formed on the light-incident surface. The recess of the second through hole has a second optical adjustment surface facing the light-emitting side surface of the light-emitting element corresponding to the second through hole. The second optical adjustment surface can be one or any combination of a second convex spherical surface, a second convex aspherical surface, or a second convex Fresnel lenticular surface. The second optical adjustment surface has a second curved surface central axis coaxial with the central optical axis of the light-emitting element corresponding to the second through hole.

[0012] In one embodiment, the second shortest distance between the second optical adjustment surface of the second through hole and the light-emitting side surface of the light-emitting element corresponding to the second through hole can be in the range of 0.04 to 0.12 mm.

[0013] According to another variation of the backlight device of the present application, the plurality of through holes further comprises at least one third through hole, each of the third through holes has a protrusion formed on the light-incident surface. The protrusion of the third through hole has a third optical adjustment surface facing the light-emitting side surface of the light-emitting element corresponding to the third through hole. The third optical adjustment surface can be one or any combination of a second concave spherical surface, a second concave aspherical surface, or a second concave Fresnel lenticular surface. The third optical adjustment surface has a third curved surface central axis coaxial with the central optical axis of the light-emitting element corresponding to the third through hole.

[0014] In one embodiment, the third shortest distance between the third optical adjustment surface of the third through hole and the light-emitting side surface of the light-emitting element corresponding to the third through hole can be in the range of 0.04 to 0.12 mm.

[0015] In one embodiment, the backlight device further comprises a light-blocking film and a reflective film, the light-blocking film is disposed on the top surface of the light guide plate, the reflective film is disposed on the back surface of the light guide plate, the light-blocking film has a plurality of light-transmitting portions, the light rays emitted by the plurality of light-emitting elements into the light guide plate are guided by the light guide plate and emitted from the plurality of light-transmitting portions of the light-blocking film, the reflective film is used to reflect the light rays emitted toward the reflective film.

[0016] In addition, the present application also provides a light-emitting keyboard comprising the aforementioned backlight device.

[0017] Different from the prior art, the backlight device for a light-emitting keyboard of the present application can adjust the beam angle of the light rays emitted by the light-emitting elements into the light guide plate. Thus, the backlight device for a light-emitting keyboard of the present application can effectively utilize the energy of the light rays emitted by the light-emitting elements. The light-emitting keyboard using the backlight device of the present application can have a uniform brightness of the pattern on the keycap.

[0018] The present application will be described in detail below with reference to the accompanying drawings and embodiments, but is not limited to the embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1FIG. 1 is a partial cross-sectional view of a backlight device for an luminous keyboard according to a preferred embodiment of the present invention.

[0020] Figure 2 FIG. 1 is a partial top view of an example of a backlight device for an luminous keyboard according to a preferred embodiment of the present invention.

[0021] Figure 3 FIG. 1 is a partial top view of another example of a backlight device for an luminous keyboard according to a preferred embodiment of the present invention.

[0022] Figure 4 FIG. 1 is a partial top view of another example of a backlight device for an luminous keyboard according to a preferred embodiment of the present invention.

[0023] Figure 5 FIG. 1 is a partial top view of another example of a backlight device for an luminous keyboard according to a preferred embodiment of the present invention.

[0024] Figure 6 FIG. 1 is a partial top view of another example of a backlight device for an luminous keyboard according to a preferred embodiment of the present invention.

[0025] Figure 7 FIG. 1 is a partial top view of a variation of a backlight device for an luminous keyboard according to a preferred embodiment of the present invention.

[0026] Figure 8 FIG. 1 is a partial top view of another variation of a backlight device for an luminous keyboard according to a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0027] In order to provide a further understanding of the purpose, structure, features, and functions of the present invention, the present invention is described in detail below with reference to the embodiments.

[0028] See also Figures 1 to 5 , Figures 1 to 5 A backlight device 1 for an illuminated keyboard according to a preferred embodiment of the present invention is schematically depicted. Figure 1 A backlight device 1 according to a preferred embodiment of the present invention is schematically illustrated in a partial cross-sectional view. Figure 2 An example of a backlight device 1 according to a preferred embodiment of the present invention is schematically shown in a partial top view. Figure 3 Another example of the backlight device 1 according to a preferred embodiment of the present invention is schematically shown in a partial top view. Figure 4 Another example of the backlight device 1 according to a preferred embodiment of the present invention is schematically shown in a partial top view. Figure 5 Another example of the backlight device 1 according to a preferred embodiment of the present invention is schematically shown in a partial top view.

[0029] like Figure 1 and Figure 2 As shown, a backlight device 1 according to a preferred embodiment of the present invention comprises a light guide plate 10 , a circuit board 12 , and a plurality of light emitting elements 14 . The light guide plate 10 has a top surface 100 , a back surface 102 , and a plurality of through holes 104 .

[0030] In one embodiment, the light guide plate 10 can be made of acrylic, silicone, thermoplastic polyurethane (TPU), or other commercial light-guiding polymer materials. The thickness of the light guide plate 10 can be determined as needed without particular limitation.

[0031] Each through hole 104 has its own light incident surface 1040 (or each through hole 104 has its own light incident surface 1040). A plurality of light-emitting elements 14 are electrically connected to the circuit board 12. Each light-emitting element 14 has its own light-emitting side surface 140 (or each light-emitting element 14 has its own light-emitting side surface 140) and its own central optical axis 142 (or each light-emitting element 14 has its own central optical axis 142), and each light-emitting element 14 corresponds to a through hole 104. The circuit board 12 is placed on the back surface 102 of the light guide plate 10, so that each light-emitting element 14 is placed in its corresponding through hole 104, and the light-emitting side surface 140 of each light-emitting element 14 faces the light incident surface 1040 of its corresponding through hole 104. Each light-emitting element 14 emits light from its light-emitting side surface 140 toward the light incident surface 1040 of its corresponding through hole 104, and then into the light guide plate 10.

[0032] In one embodiment, the light emitting element 14 may be a light emitting diode or an organic light emitting diode, but the present invention is not limited thereto.

[0033] In particular, the plurality of through holes 104 include at least one first specific through hole 104a, defined as at least one first through hole 104a. Each first through hole 104a has a first optical adjustment surface 1041 on its light incident surface 1040. The first optical adjustment surface 1041 can be one of a first convex spherical surface, a first concave spherical surface, a first concave aspherical surface, a first convex aspherical surface, a first Fresnel concave arc surface, or a first Fresnel convex arc surface. The first optical adjustment surface 1041 has a first curved central axis 1042 that is coaxial with the central optical axis 142 of the corresponding light emitting element 14. Figure 2 In the example shown, the first optical adjustment surface 1041 is a first convex spherical surface. Figure 3 In the example shown, the first optical adjustment surface 1041 is a first concave spherical surface. Figure 4 In the example shown, the first optical adjustment surface 1041 is a first Fresnel convex arc surface. Figure 5In the illustrated example, the first optical adjustment surface 1041 is a first Fresnel convex arc surface. Figure 3 , Figure 4 and Figure 5 have the same reference numerals as the elements in Figure 2 have the same or similar structures and functions, and will not be described again. When the first optical adjustment surface 1041 is a first convex spherical surface, a first convex aspherical surface, or a first Fresnel convex arc surface, the light beam angle of the light emitted by the light emitting element 14 into the light guide plate 10 is contracted, that is, selecting a suitable first optical adjustment surface 1041 according to the structure of the light guide plate 10 has a converging effect on the light emitted by the light emitting element 14. When the first optical adjustment surface 1041 is a first concave spherical surface, a first concave aspherical surface, or a first Fresnel concave arc surface, the light beam angle of the light emitted by the light emitting element 14 into the light guide plate 10 is widened, that is, selecting a suitable first optical adjustment surface 1041 according to the structure of the light guide plate 10 has a diverging effect on the light emitted by the light emitting element 14. In this way, by designing the light-incident surface 1040 of the at least one first through hole 104a, the light beam angle of the light emitted by the light emitting element 14 into the light guide plate 10 can be adjusted to meet the actual needs.

[0034] In actual operation, when there is a structure in a local area of the backlight device 1 that affects the normal transmission of light, the through hole corresponding to the light emitting element 14 at this location can be set as the first through hole 104a, and at this time the first optical adjustment surface 1041 of the first through hole 104a is one of a first convex spherical surface, a first convex aspherical surface, or a first Fresnel convex arc surface. In this way, the light emitted by the light emitting element placed therein will be contracted (to form a converging light beam), so that the structure affecting the normal transmission of light can be bypassed, and the decrease in light uniformity at this location can be avoided.

[0035] In actual operation, when the overall brightness requirement of the light provided by a local area or the entire area of the backlight device 1 is not high or the brightness of the light provided by the light emitting element 14 is sufficient, at least one through hole corresponding to a light emitting element 14 can be set as the first through hole 104a, and at this time the first optical adjustment surface 1041 of the first through hole 104a is one of a first concave spherical surface, a first concave aspherical surface, or a first Fresnel concave arc surface. In this way, the light emitted by the light emitting element 14 placed therein will be diffused to a greater extent (to form a diverging light beam), so that the number of light emitting elements and through holes in the entire backlight device 1 can be reduced, and the efficiency can be improved.

[0036] In a specific embodiment, the first optical adjustment surface 1041 can be formed by stamping or computer numerical control tool machining.

[0037] In one embodiment, in order to accommodate the placement of the plurality of light emitting elements 14 in the corresponding through holes 104, and to take into account the manufacturing tolerances of the light guide plate 10, the circuit board 12, and other components, the first shortest distance range dl between the first optical adjustment surface 1041 of the first through hole 104a and the light emitting side surface 140 of the corresponding light emitting element 14 can be 0.04-0.12 mm. The first shortest distance range dl takes into account the optical design parameters (e.g., focal length) of the first optical adjustment surface 1041.

[0038] Referring to Figure 6 , Figure 6 Another example of a backlight device 1 according to a preferred embodiment of the present application is schematically illustrated in a partial top view. As Figure 6 shown, in one embodiment, the light guide plate 10 further has a first break hole 106. The first break hole 106 is located on a first original optical path PI of light rays entering the light guide plate 10 from the light entry surface 1040 of the first through hole 104a. Here, the first original optical path PI refers to the path of a boundary of a light beam traveling in the light guide plate 10 that enters the light entry surface 1040 of the first through hole 104a that is only a flat surface and has no first optical adjustment surface 1041 thereon. As is apparent, the light rays traveling along the first original optical path PI encounter the first break hole 106. The first adjusted optical path P2 of the light rays after being adjusted by the first optical adjustment surface 1041 of the first through hole 104a and entering the light guide plate 10 does not pass through the first break hole 106. Here, the first adjusted optical path P2 is also the path of a boundary of a light beam traveling in the light guide plate 10. Figure 6 The elements having the same reference numerals in Figure 2 have the same or similar structures and functions, and will not be described again.

[0039] Also as Figure 6 shown, in one embodiment, the light guide plate 10 further has a second break hole 108. The second break hole 108 is located on a second original optical path P3 of light rays entering the light guide plate 10 from the light entry surface 1040 of the first through hole 104a. Here, the second original optical path P3 refers to the path of another boundary of a light beam traveling in the light guide plate 10 that enters the light entry surface 1040 of the first through hole 104a that is only a flat surface and has no first optical adjustment surface 1041 thereon. As is apparent, the light rays traveling along the second original optical path P3 encounter the second break hole 108. The second adjusted optical path P4 of the light rays after being adjusted by the first optical adjustment surface 1041 of the first through hole 104a and entering the light guide plate 10 does not pass through the second break hole 108. Here, the second adjusted optical path P4 is also the path of another boundary of a light beam traveling in the light guide plate 10. The first adjusted optical path P2 and the second adjusted optical path P4 are located between the first break hole 106 and the second break hole 108. AsFigure 6 In the embodiment shown, the first aperture 106 and the second aperture 108 are the structures that affect the normal transmission of light. By adjusting the first optical adjustment surface 1041 on the light-incident surface 1040 of the at least one first through-hole 104a, the optical path can avoid the aperture area, thereby avoiding the problem of poor uniformity caused by the over-brightness of the aperture area. Thus, the backlight device 1 according to the preferred embodiment of the present application can effectively utilize the energy of the light emitted by the light-emitting element 14.

[0040] The backlight device 1 according to the preferred embodiment of the present application further comprises a light-blocking film (not shown in the figure) and a reflective film (not shown in the figure). The light-blocking film is arranged on the top surface 100 of the light guide plate 10. The reflective film is arranged on the back surface 102 of the light guide plate 10. The light-blocking film has a plurality of light-transmitting portions. The light incident into the light guide plate 10 is guided by the light guide plate 10 and emitted from the plurality of light-transmitting portions of the light-blocking film. The reflective film is used to reflect the light directed toward the reflective film.

[0041] Please refer to Figure 7 , Figure 7 A variant of the backlight device 1 according to the preferred embodiment of the present application is schematically shown in a partial top view. As shown in Figure 7 In the variant of the backlight device 1 according to the preferred embodiment of the present application, the plurality of through-holes 104 further has at least one second specific through-hole 104b, defined as at least one second through-hole 104b. Each second through-hole 104b has a recess 1043 formed on the light-incident surface 1040. The recess 1043 of the second through-hole 104b has a second optical adjustment surface 1044 facing the light-emitting side surface 140 of the light-emitting element 14 corresponding thereto. The second optical adjustment surface 1044 can be one or any combination of a second convex spherical surface, a second convex aspherical surface, or a second Fresnel convex arc surface. The second optical adjustment surface 1044 has a second curved central axis 1045 coaxial with the central optical axis 142 of the light-emitting element 14 corresponding thereto. In Figure 7 In the example shown, the second optical adjustment surface 1044 is a second convex spherical surface. Figure 7 The elements having the same reference numerals in Figure 2 The elements having the same reference numerals in

[0042] In actual operation, when there is a structure such as a broken hole in a local area of the backlight device that affects the normal transmission of light, the through hole corresponding to at least one light emitting element can be set as a second through hole. In this way, the light emitted by the light emitting element placed therein will be contracted (to form a convergent light beam), thereby avoiding the structure that affects the normal transmission of light and avoiding the decrease in light uniformity caused thereby.

[0043] In a specific embodiment, similarly, in order to accommodate the placement of the plurality of light emitting elements 14 in the corresponding through holes 104 and taking into account the processing and manufacturing tolerances of the light guide plate 10, the circuit board 12 and other elements and components, the second shortest distance range d2 between the second optical adjustment surface 1044 of the second through hole 104b and the light emitting side surface 140 of the corresponding light emitting element 14 can be 0.04-0.12 mm. The second shortest distance range d2 takes into account the optical design parameters (e.g., focal length) of the second optical adjustment surface 1044.

[0044] Please refer to Figure 8 , Figure 8 Another variant of the backlight device 1 according to the preferred embodiment of the present application is schematically shown in a partial top view. As Figure 8 shown, in another variant of the backlight device 1 according to the preferred embodiment of the present application, the plurality of through holes 104 further has at least one third specific through hole 104c, defined as at least one third through hole 104c, each third through hole 104c having a protrusion 1046 formed on the light entry surface 1040. The protrusion 1046 of the third through hole 104c has a third optical adjustment surface 1047 facing the light emitting side surface 140 of the corresponding light emitting element 14. The third optical adjustment surface 1047 can be one or any combination of a second concave spherical surface, a second concave aspherical surface or a second Fresnel concave arc surface. The third optical adjustment surface 1047 has a third curved central axis 1048 coaxial with the central optical axis 142 of the corresponding light emitting element 14. In Figure 8 the example shown, the third optical adjustment surface 1047 is a second concave spherical surface. Figure 8 The elements having the same reference numerals in Figure 2 have the same or similar structure and function, which will not be described in detail. When the third optical adjustment surface 1047 is a second concave spherical surface, a second concave aspherical surface, a second Fresnel concave arc surface or any combination thereof, the light beam angle of the light emitted by the light emitting element 14 into the light guide plate 10 is widened, that is, the third optical adjustment surface 1047 has a diffusing effect on the light emitted by the light emitting element 14.

[0045] In actual operation, when the overall brightness requirement of the light provided by the local area or the overall area of the backlight device is not high or the brightness of the light provided by the light emitting element body is sufficient, the through hole corresponding to at least one light emitting element can be set as a third through hole. In this way, the light emitted by the light emitting element placed therein will be diffused to a greater extent (forming a diffuse light beam), thereby reducing the amount of light emitting elements and the number of through holes in the entire backlight device, and improving the efficiency.

[0046] In a specific embodiment, similarly, in order to accommodate the placement of the plurality of light emitting elements 14 in the corresponding through holes 104 and taking into account the processing and manufacturing tolerances of the light guide plate 10, the circuit board 12 and other elements and components, the third shortest distance range d3 between the third optical adjustment surface 1047 of the third through hole 104c and the light emitting side surface 140 of the corresponding light emitting element 14 can be 0.04-0.12mm. And the third shortest distance range d3 takes into account the optical design parameters (such as focal length) of the third optical adjustment surface 1047.

[0047] In addition, the application also discloses a light-emitting keyboard (not shown), which comprises the aforementioned backlight device 1, and the pattern brightness on each keycap of the light-emitting keyboard is uniform.

[0048] Through the above detailed description of the application, it can be clearly understood that the backlight device for a light-emitting keyboard according to the application can adjust the angle of the light beam emitted by the light emitting element into the light guide plate. Therefore, the backlight device for a light-emitting keyboard according to the application effectively utilizes the energy of the light emitted by the light emitting element. The light-emitting keyboard using the backlight device according to the application has uniform brightness of the pattern on the keycap.

[0049] Of course, the application can have other various embodiments, and those skilled in the art can make various corresponding changes and modifications according to the application without departing from the spirit and essence of the application. However, these corresponding changes and modifications should all belong to the protection scope of the claims attached to the application.

Claims

1. A backlight device for an luminous keyboard, characterized in that The light guide plate has a top surface, a back surface, and a plurality of through holes, each of the through holes having an entrance surface; a circuit board; and a plurality of light emitting elements, each electrically connected to the circuit board, each of the light emitting elements having a light emitting side and a central optical axis, and each of the light emitting elements corresponding to one of the through holes, wherein the circuit board is disposed on the back surface of the light guide plate such that each of the light emitting elements is positioned in the corresponding through hole, and the light emitting side of each of the light emitting elements faces the entrance surface of the corresponding through hole, and each of the light emitting elements emits light from the light emitting side toward the entrance surface of the corresponding through hole and into the light guide plate; wherein the plurality of through holes includes at least one first through hole, the entrance surface of each of the first through holes has a first optical adjustment surface selected from one of a first concave spherical surface, a first convex spherical surface, a first concave aspherical surface, a first convex aspherical surface, a first concave Fresnel curved surface, and a first convex Fresnel curved surface, the first optical adjustment surface has a first central surface axis coaxial with the central optical axis of the corresponding light emitting element; the light guide plate further has a first broken hole located on a first original optical path of the light emitted from the entrance surface of the first through hole into the light guide plate, and a first adjusted optical path of the light emitted from the first optical adjustment surface of the first through hole into the light guide plate does not pass through the first broken hole, wherein the first original optical path refers to a path of a light beam entering the entrance surface of the first through hole which is a flat surface without the first optical adjustment surface, and a boundary of the light beam in the light guide plate. A first shortest distance between the first optical adjustment surface of the first through hole and the light emitting side of the corresponding light emitting element ranges from 0.04 mm to 0.12 mm.

2. The backlight device according to claim 1, wherein The light guide plate further has a second broken hole located on a second original optical path of the light emitted from the entrance surface of the first through hole into the light guide plate, and a second adjusted optical path of the light emitted from the first optical adjustment surface of the first through hole into the light guide plate does not pass through the second broken hole, the first adjusted optical path and the second adjusted optical path are located between the first broken hole and the second broken hole.

3. The backlight device according to claim 1, wherein The plurality of through holes further includes at least one second through hole, each of the second through holes has a recess formed on the entrance surface, the recess has a second optical adjustment surface facing the light emitting side of the corresponding light emitting element, the second optical adjustment surface is selected from one of a second convex spherical surface, a second convex aspherical surface, and a second convex Fresnel curved surface or any combination thereof, the second optical adjustment surface has a second central surface axis coaxial with the central optical axis of the corresponding light emitting element.

4. The backlight of claim 1, wherein A second shortest distance between the second optical adjustment surface of the second through hole and the light emitting side of the corresponding light emitting element ranges from 0.04 mm to 0.12 mm.

5. The backlight of claim 4, wherein ​ 6. The backlight of claim 1, wherein The plurality of through holes further comprises at least one third through hole, each of the third through hole has a protrusion formed on the light-in surface, the protrusion has a third optical adjustment surface facing the light-emitting side surface of the light-emitting element corresponding thereto, the third optical adjustment surface is selected from one or any combination of a second concave spherical surface, a second concave aspherical surface and a second Fresnel concave arc surface, and the third optical adjustment surface has a third curved surface center axis coaxial with the central optical axis of the light-emitting element corresponding thereto.

7. The backlighting device of claim 6, wherein, The third shortest distance between the third optical adjustment surface of the third through hole and the light-emitting side surface of the light-emitting element corresponding thereto ranges from 0.04 to 0.12 mm.

8. The backlight of claim 1, wherein, The backlight device further comprises a light-blocking film and a reflective film, the light-blocking film is arranged on the top surface of the light guide plate, the reflective film is arranged on the back surface of the light guide plate, the light-blocking film has a plurality of light-transmitting portions, the light rays emitted by the plurality of light-emitting elements into the light guide plate are guided by the light guide plate and emitted from the plurality of light-transmitting portions of the light-blocking film, and the reflective film is used to reflect the light rays emitted toward the reflective film.

9. A lighted keyboard, comprising: A backlight device comprising any one of claims 1 to 8.

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