JPH05167659A - Lighting device for key operation section - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a key operation unit lighting device which is miniaturized and thinned, and is capable of uniformly illuminating characters for clear recognition. [Structure] The LED 19 mounted on the printed circuit board 2 is placed in a hole 21 formed in the light guide plate 4. The hole 21 is closed by the reflection sheet 22 on the key sheet 3 side of the light guide plate 4. LED
The light from 19 is prevented from going straight to the side of the key sheet 3 by the reflection sheet 22, and the light is reflected, and further reflected by the light guide plate 4, the key sheet 3 and the printed circuit board 2, and the light guide plate 4 is provided with its end face. Most of the light is diffused almost evenly throughout.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lighting device for a key operation unit used in a mobile telephone or the like.

[0002]

2. Description of the Related Art Conventionally, when a key is operated in a dark place such as a mobile telephone, the key operation portion is illuminated to prevent a key operation error.

A conventional key operating portion lighting device will be described below with reference to the sectional view shown in FIG.

In FIG. 5, 1 is a key case, 2 is a printed circuit board attached to the key case 1 with screws (not shown), etc., and 3, 4, and 5 are provided between the key case 1 and the printed circuit board 2. Key sheet, light guide plate and membrane sheet.

In the membrane sheet 5, a spacer 8 is interposed between a pair of membranes 6 and 7, and spaces 9 are formed at a plurality of crossing portions between the membranes 6 and 7 in the vertical and horizontal directions.
Inside, switch contacts 10 and 11 for dials and the like are provided so as to face the insides of the membranes 6 and 7, and a hole 12 is formed in the center of the four sets of switch contacts 10 and 11.
Are formed. The light guide plate 4 is made of acrylic resin,
A hole 13 is formed corresponding to each set of switch contacts 10 and 11 of the membrane sheet 5, and a recess 14 is formed corresponding to each hole 12 of the membrane sheet 5 from the membrane sheet 5 side. The key sheet 3 is provided with key tops 15 corresponding to the switch contacts 10 and 11 of each set of the membrane sheet 5 and the holes 13 of the light guide plate 4, and each key top 15 is formed from the holes 16 formed in the key case 1. It is projected outward. A switch operating portion 17 protruding from the back side of each key top 15 is inserted into the hole 13 of the light guide plate 4 and faces the diaphragm 18 provided on the membrane sheet 5 in the hole 13. An LED (light emitting diode) 19 which is a light emitting body mounted on the printed circuit board 2 is inserted into the hole 12 of the membrane sheet 5 and inserted into the recess 14 of the light guide plate 4.

In the above structure, the light from the LED 19 is diffused by the light guide plate 4, the key sheet 3 and the printed circuit board 2 to illuminate the key top 15 and the characters 20 printed on the key top 15 (see FIG. 4). Can be recognized in the dark. Therefore, the key operation can be easily performed in the dark.

[0007]

However, in the above-mentioned conventional key operation part illumination device, in order to uniformly illuminate the entire character 20 on the key top 15, the thickness of the light guide plate 4 or the key sheet 3 is increased. It was necessary to increase the light diffusion effect by increasing the pitch of the key tops 15. For this reason, there is a limit to miniaturization and thinning of the key operation unit,
It is not possible to cope with the recent trend toward lighter, thinner, smaller products. Further, since the existence of the LED 19 can be seen from the outside of the key case 1, there is a problem in that it is not preferable in appearance.

The present invention solves such a conventional problem, can be made compact and thin, and can be used for light, thin, short, and small devices, and can evenly illuminate characters. It is an object of the present invention to provide a key operation part lighting device which can be clearly recognized and whose appearance can be improved by not knowing the existence of a light emitter from the outside.

[0009]

In order to achieve the above object, the present invention is mounted on a light guide plate provided inside a key sheet and a printed circuit board, and is housed in a hole formed in the light guide plate. And a reflection sheet provided so as to close a hole accommodating the light emitting body on the key sheet side of the light guide plate.

Positioning ribs are provided on the light guide plate, projections for aligning with the ribs are provided on the outer edge of the reflection sheet, and the projections are aligned with the ribs to attach the reflection sheet to the light guide plate. Preferably.

[0011]

Therefore, according to the present invention, the light from the light-emitting body is prevented from going straight to the key sheet side by the reflection sheet to reflect the light, and the light is largely evenly distributed to the end surface of the light guide plate. The light displayed on each key top of the key sheet can be evenly illuminated. As described above, since the light from the light emitting body is efficiently guided to the light guide plate by the reflection sheet, the thickness of the light guide plate and the key sheet can be made thin, and even if the pitch of the key top is narrowed, it is still on each key top. The letters can be illuminated evenly. Further, the light-emitting body can be hidden from the outside by the reflection sheet.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIGS. 1 to 4 show a key operating portion illumination device according to an embodiment of the present invention. FIG. 1 is a sectional view corresponding to the arrow AA of FIG. 4, FIG. 2 is an exploded perspective view, and FIG. Is an exploded perspective view showing the relationship between the light guide plate and the reflection sheet, and FIG. 4 is a partially enlarged perspective view of the key sheet.

In the present embodiment, the same parts as those in the above-mentioned conventional example are designated by the same reference numerals, the description thereof will be omitted, and a different structure will be described.

As shown in FIGS. 1 and 2, a hole 21 is formed in the light guide plate 4 in place of the recess 14 of the conventional example, and an LED 19 mounted on the printed board 2 is formed in the hole 12 of the membrane sheet 5. It is inserted and inserted into the hole 21 of the light guide plate 4. A reflection sheet 22 is attached on the key sheet 3 side of the light guide plate 4 so as to close the hole 21 accommodating the LED 19, and the reflection sheet 22 blocks the light from the LED 19 from going straight to the key sheet 3 side. ing.
Then, as shown in FIG. 3, the ribs 23 for alignment are provided on the light guide plate 4, and the projections 24 provided on the outer edge of the reflection sheet 22 are attached to the ribs 23 so that the reflection is performed. The positional deviation of the sheet 22 is eliminated, and the sticking work becomes easy. In FIG. 2, 25 is a contact portion of the membrane sheet 5, 26 is a contact portion of the printed circuit board 2,
Reference numeral 27 is a conductive rubber that electrically connects the contact portions 25 and 26.

In the above structure, the light from the LED 19 is blocked from going straight to the key sheet 3 side by the reflection sheet 22, the light is reflected, and further reflected by the light guide plate 4, the key sheet 3 and the printed circuit board 2. Therefore, a large amount of light can be diffused substantially evenly over the light guide plate 4 to the end face thereof. As a result, each key top 1 of the key sheet 3
Characters 20 (see FIG. 4) printed on No. 5 can be uniformly illuminated and can be clearly recognized in the dark.
Therefore, the key operation can be performed easily and reliably in the dark.

As described above, according to the above embodiment, the light from the LED 19 is efficiently guided by the reflection sheet 22 by the reflection sheet 22.
Since a large amount of light reaches the end surface of the light guide plate 4, the characters of each key top 15 can be reduced even if the thickness of the light guide plate 4 and the key sheet 3 is reduced and the pitch of the key tops 15 is narrowed. 20 can be uniformly illuminated. Moreover, the LED 19 can be hidden from the outside by the reflection sheet 22. Further, by aligning the protrusion 24 of the reflection sheet 22 with the alignment rib 23 of the light guide plate 4, the positional deviation of the reflection sheet 22 can be eliminated and the attachment can be easily performed.

[0018]

As described above, according to the present invention, the light from the light emitting body is prevented from going straight to the key sheet side by the reflection sheet to reflect the light, and the light guide plate is entirely covered up to the end face thereof. It is possible to diffuse a large amount of light almost evenly on the key sheet and evenly illuminate the characters displayed on each key top of the key sheet. As described above, since the light from the light emitting body is efficiently guided to the light guide plate by the reflection sheet, the thickness of the light guide plate and the key sheet can be made thin, and even if the pitch of the key top is narrowed, it is still on each key top. The letters can be illuminated evenly. Therefore, it is possible to reduce the size and thickness of a device used, and it is possible to make the device thinner, lighter, shorter, and smaller, and also to clearly recognize characters. Also,
The light-emitting body can be hidden from the outside by the reflection sheet.
Therefore, the appearance can be improved.

Further, by aligning the protrusion provided on the outer edge of the reflection sheet with the alignment rib of the light guide plate, the positional deviation of the reflection sheet can be eliminated and the attachment work can be easily performed.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a key operation unit lighting device according to an embodiment of the present invention, which is taken along the line AA of FIG.

FIG. 2 is an exploded perspective view showing the key operation unit illumination device.

FIG. 3 is an exploded perspective view showing a relationship between a light guide plate and a reflection sheet used in the key operation unit lighting device.

FIG. 4 is a partially enlarged perspective view of a key sheet used in the key operation unit lighting device.

FIG. 5 is a cross-sectional view showing a conventional key operation unit lighting device, similar to FIG.

[Explanation of symbols]

 1 Key Case 2 Printed Circuit Board 3 Key Sheet 4 Light Guide Plate 5 Membrane Sheet 10 Switch Contact 11 Switch Contact 15 Key Top 19 LED 21 Hole 22 Reflective Sheet 23 Rib 24 Projection

Claims (2)

[Claims] 1. A light guide plate provided inside a key sheet, a light-emitting body mounted on a printed circuit board and housed in a hole formed in the light guide plate, and the light-emitting plate on the key sheet side of the light guide plate. A key operation unit lighting device comprising: a reflection sheet provided so as to close a hole accommodating a body. 2. The key operation part lighting device according to claim 1, wherein a positioning rib is provided on the light guide plate, and a projection for positioning the rib is provided on an outer edge of the reflection sheet.