JP2816619B2 - Key operation unit illumination device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

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

Hereinafter, a conventional key operation unit illumination device will be described with reference to a 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), 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.

[0005] 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 locations intersecting vertically and horizontally between the membranes 6 and 7.
In the inside, switch contacts 10 and 11 for a dial and the like are provided facing the inside 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 an acrylic resin,
A hole 13 is formed corresponding to each set of switch contacts 10 and 11 of the membrane sheet 5, and a concave portion 14 recessed from the membrane sheet 5 side is formed corresponding to each hole 12 of the membrane sheet 5. The key sheet 3 is provided with key tops 15 corresponding to the switch contacts 10, 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 inserted through a hole 16 formed in the key case 1. It protrudes outward. A switch operation portion 17 protruding from the rear 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 emitter mounted on the printed circuit board 2, is inserted into the hole 12 of the membrane sheet 5 and is inserted into the recess 14 of the light guide plate 4.

In the above configuration, 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 character 20 printed on the key top 15 (FIG. 4). ) Can be recognized in the dark. Therefore, key operations can be easily performed in the dark.

[0007]

However, in order to uniformly illuminate the entire character 20 on the key top 15 in the conventional key operation unit illumination device, the thickness of the light guide plate 4 or the key sheet 3 is increased. Therefore, it is necessary to increase the light diffusion effect by increasing the pitch of the key tops 15 or the like. For this reason, there is a limit to the miniaturization and thinning of the key operation unit,
In recent years, it is not possible to cope with the reduction in size of products. Further, since the presence of the LED 19 can be recognized from the outside of the key case 1, there is a problem that the appearance is not preferable.

The present invention has been made to solve such a conventional problem, and can cope with a reduction in the size and thickness of a device to be used. It is an object of the present invention to provide a key operation unit illuminating device that can be clearly recognized and that can improve the appearance by preventing the presence of a light emitting body from being recognized from the outside.

[0009]

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

[0010] Then, a rib for positioning is provided on the light guide plate, a projection is provided on the outer edge of the reflection sheet for positioning the rib, and the projection is positioned on the rib and the reflection sheet is attached to the light guide plate. Is preferred.

[0011]

Therefore, according to the present invention, the light from the illuminant is prevented from going straight to the key sheet side by the reflection sheet to reflect the light, and the light guide plate almost uniformly spreads the light to the end face. The characters displayed on each key top of the key sheet can be evenly illuminated. And, as described above, the light from the illuminant is efficiently guided to the light guide plate by the reflection sheet, so that the thickness of the light guide plate and the key sheet is reduced, and even if the pitch of the key tops is narrowed, each key top is kept on top. Can be evenly illuminated. Further, the light emitting body can be hidden from the outside by the reflection sheet.

[0012]

An embodiment of the present invention will be described below with reference to the drawings.

FIGS. 1 to 4 show a key operation unit illuminating device according to an embodiment of the present invention. FIG. 1 is a cross-sectional view taken along the line AA of FIG. 4, 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 this embodiment, the same parts as those of the above-described conventional example are denoted by the same reference numerals, and the description thereof will be omitted.

[0015] As shown in FIGS. 1 and 2, the light guide plate 4 holes 21 in place of the concave portion 14 of the prior art is formed, LED 19 mounted on the printed circuit board 2 a hole 12 of the membrane sheet 5 And is inserted into the hole 21 of the light guide plate 4. The hole 21 accommodating the LED 19 is closed on the key sheet 3 side of the light guide plate 4 , and the light of the LED 19 is
ー In order to prevent going straight to the seat 3 side,
A reflection sheet 22 facing the LED 19 is attached, and the reflection sheet 22 prevents light from the LED 19 from going straight to the key sheet 3 and reflects the light toward the light guide plate 4. Then, as shown in FIG. 3, a rib 23 for positioning is provided on the light guide plate 4, and the reflection sheet 22 is provided.
The projection 24 provided on the outer edge of the reflection sheet 22 is adhered so as to be aligned with the rib 23, whereby the displacement of the reflection sheet 22 is eliminated, and the attachment work is facilitated. In FIG. 2,
25 is a contact portion of the membrane sheet 5, 26 is a contact portion of the printed circuit board 2, and 27 is a conductive rubber for electrically connecting the contact portions 25 and 26.

In the above configuration, the light from the LED 19 is prevented from traveling straight to the key sheet 3 by the reflection sheet 22 and reflected by the reflection sheet 22, and further reflected by the light guide plate 4, the key sheet 3 and the printed board 2. In addition, a large amount of light can be diffused almost uniformly over the entire light guide plate 4 up to its end face. Thereby, each key top 1 of the key sheet 3
The characters 20 (see FIG. 4) printed on 5 can be evenly illuminated, and can be clearly recognized in darkness.
Therefore, key operations can be easily and reliably performed in darkness.

As described above, according to the above embodiment, the light from the LED 19 is efficiently transmitted to the light guide plate 4 by the reflection sheet 22.
So that a large amount of light reaches the end face of the light guide plate 4. Therefore, 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, the character of each key top 15 is reduced. 20 can be evenly illuminated. Further, the LED 19 can be hidden from the outside by the reflection sheet 22. Further, by aligning the projections 24 of the reflection sheet 22 with the positioning ribs 23 of the light guide plate 4, the displacement of the reflection sheet 22 can be eliminated, and the reflection sheet 22 can be easily attached.

[0018]

As described above, according to the present invention, the light from the luminous body is prevented from going straight to the key sheet side by the reflection sheet, and the light is reflected. A large amount of light can be diffused almost uniformly, and the characters displayed on each key top of the key sheet can be evenly illuminated. And, as described above, the light from the illuminant is efficiently guided to the light guide plate by the reflection sheet, so that the thickness of the light guide plate and the key sheet is reduced, and even if the pitch of the key tops is narrowed, each key top is kept on top. Can be evenly illuminated. Therefore, it is possible to cope with the reduction in size and thickness of the device used, and to make it possible to recognize characters clearly. Also,
The luminous body can be hidden from the outside by the reflection sheet.
Therefore, the appearance can be improved.

Further, by aligning the projection provided on the outer edge of the reflection sheet with the positioning rib of the light guide plate, the displacement of the reflection sheet can be eliminated and the sticking operation can be performed easily.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a key operation unit illumination device according to an embodiment of the present invention, and is equivalent to a view taken along 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 illumination device.

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

FIG. 5 shows a conventional key operation unit illumination device, and is a cross-sectional view similar to FIG.

[Explanation of symbols]

 DESCRIPTION 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 Reflection sheet 23 Rib 24 Projection

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-52-58881 (JP, A) JP-A-61-105928 (JP, A) JP-A 1-1124750 (JP, U) JP-A 2- 65828 (JP, U)

Claims (2)

(57) [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 emission on the key sheet side of the light guide plate. Close the hole containing the body , and
And a reflection sheet provided with a reflection surface facing the light emitting body side so as to block the light from traveling straight to the key sheet side . 2. The key operation unit illumination 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.