JPH10125162A - Operating key lighting system for small electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an operating key lighting system, capable of inexpensively and surely preventing light leakage. SOLUTION: A light-leakage preventive sheet 10, wherein a surface and a back surface are adopted as light low-/high-reflectance surfaces respectively, is provided between a key pad rubber 5 and an electronic circuit board 6 provided with a luminous element 8, and also a key sheet 9 is provided on the surface of the board 6. The surface of the key sheet 9 is made to have a high- reflectance surface, thereby preventing light leakage on the surface of he light- leakage preventive sheet 10, and reflecting and diffusing light on the back surface of the light-leakage preventive sheet 10 and the surface of the key sheet 9.

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 operating keys of small electronic equipment.

[0002]

2. Description of the Related Art Small electronic devices, particularly portable electronic devices, are used in various environments, such as outdoor use, and are often used in dark places. For this reason, many devices have a backlight function for illuminating operation keys for the purpose of improving operability in a dark place.

The backlight of the operation keys is illuminated so that the operation keys can be individually identified from the viewpoint of operability in a dark place, designability, and power saving.

A conventional operation key illumination device is described below.

The switch unit is mounted on a switch circuit board,
A key sheet provided with a switch corresponding to each operation key, and a configuration in which key buttons are bonded or integrally molded with a keypad rubber are provided. The key buttons and the keypad rubber have translucency, and the key buttons are illuminated by light emitting elements such as light emitting diodes provided on the switch circuit board.

[0006] Also, characters and symbols can be distinguished by illuminating key buttons so that the functions and types of the normal operation keys can be distinguished. However, characters and symbols can be reliably recognized in a dark place. To have enough contrast,
For that purpose, it is necessary to prevent light leakage which causes noise.

In the conventional light leakage prevention, when the key button is made of rubber and the key button is formed integrally with the keypad rubber, black printing or painting is applied to the entire surface of the keypad rubber to prevent light leakage. In the case where the key buttons are made of a transparent resin and a key pad rubber is used as a key button holder, the surface of the key pad rubber is similarly black-printed or painted to prevent light leakage.

[0008]

In the above conventional example,
Black printing and painting on the surface of the keypad rubber,
There was a problem that the cost was increased due to this surface treatment.

The present invention has been made in view of the above circumstances, and has as its object to provide an operation key illumination device for a small electronic device which is inexpensive and can surely prevent light leakage.

[0010]

According to the present invention, there is provided a light leakage preventing sheet having a low light reflectance surface on a front surface and a high light reflectance surface on a back surface between a keypad rubber and an electronic circuit board provided with a light emitting element. And a key sheet is provided on the surface of the electronic circuit board, and the surface of the key sheet is made to have a high reflectance surface, or the surface of the key sheet is covered with metal foil.

Since the surface of the light leakage prevention sheet has a low light reflectance surface, light leakage is prevented. Further, since the back surface of the light leakage prevention sheet and the surface of the key sheet are made high reflectance surfaces, light is reflected and diffused between the two. You. Further, by covering the surface of the key sheet with metal foil, a shielding effect is produced.

[0012]

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

In FIG. 1, reference numeral 1 denotes a front panel of a small electronic device. The front panel 1 has a key button hole 3 into which a key button 2 is fitted. In the figure, reference numeral 4 denotes a keypad. The keypad 4 is bonded to a keypad rubber 5 made of a translucent milky white silicone rubber material and to a position corresponding to the key button hole 3 of the keypad rubber 5. Key button 2. The key button 2 is made of a transparent resin material, and the key button 2 has a flange 2a larger than the key button hole 3 around the bottom surface.
The bottom of the key button 2 is printed with a solid character (symbol). For this printing, a light-shielding property, for example, black or the like is selected.

The keypad 4 is provided between the front panel 1 and the electronic circuit board 6 so as to be pressed against the front panel 1 by the electronic circuit board 6. Is held by the claw 7 formed on the base. A light-emitting element 8 such as a light-emitting diode is provided at a required position on the surface of the electronic circuit board 6 (side surface of the front panel 1).

A key sheet 9 is provided on the surface of the electronic circuit board 6 and has a contact for disconnection, and has a function of bringing the contact into contact with and separating from the contact on the electronic circuit board 6. An escape hole 12 is formed in the key sheet 9 at a position corresponding to the light emitting element 8, and the light emitting element 8 projects from the key sheet 9. Further, a sheet of a mirror surface material such as aluminum foil is stuck on the surface of the key sheet 9. By attaching a metal pad such as an aluminum foil to the surface of the key sheet 9, a shielding effect is produced.

A light leakage prevention sheet 10 is sandwiched between the key sheet 9 and the keypad rubber 5.
Are black on the front surface and white on the back surface. The light leakage prevention sheet 10 corresponds to the key button 2,
A light-transmitting hole 11 having the same shape as that of FIG. Further, a positioning hole (not shown) is formed at a required portion of the light leakage prevention sheet 10, and the positioning hole is formed with a positioning projection (not shown) projecting from the back surface of the keypad rubber 5. Mate,
Positioning is performed. The light leakage prevention sheet 10 prevents light leakage by the black color on the front side, and reflects and diffuses the white back surface and the mirror surface of the key sheet 9.

Hereinafter, the operation will be described.

When the light emitting element 8 emits light, the light emitted from the light emitting element 8 enters the keypad rubber 5, and further transmits the light that is not covered by the light leakage prevention sheet 10 of the key sheet 9. The light reflected by the light hole 11 is uniformly diffused throughout the keypad rubber 5, and the key button 2
To illuminate. At this time, light penetrates from the end face of the flange 2a of the key button 2 from the key pad rubber 5, and light leaks from a gap between the front panel 1 and the key button 2. Since the light leakage prevention sheet 10 provided on the back surface is black except for the key top portion of the key button 2, light leakage is not recognized. The light incident between the light leakage prevention sheet 10 and the key sheet 9 is white on the back surface of the light leakage prevention sheet 10 and is reflected between the light leakage prevention sheet 10 and the key sheet 9. Has no effect.

The front surface of the light leakage prevention sheet 10 is not limited to black and has a low reflectance, and the back surface is not limited to white but may be any material that reflects light at a light color or a mirror surface. Similarly, the surface of the key sheet 9 is not limited to a mirror surface but may be any surface having a high light reflectance.

[0020]

As described above, according to the present invention, by providing the light leakage prevention sheet, printing on the keypad rubber can be omitted, the cost can be reduced, and the key sheet surface can be covered with metal such as aluminum foil. When covered, the shield effect is exhibited.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing an embodiment of the present invention.

FIG. 2 is a front sectional view of the same.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Front panel 2 Key button 5 Keypad rubber 6 Electronic circuit board 8 Light emitting element 9 Key sheet 10 Light leakage prevention sheet

Claims (2)

[Claims] 1. A light leakage prevention sheet having a light-reflecting surface on a front surface and a light-reflecting surface on a rear surface is provided between a keypad rubber and an electronic circuit board on which a light emitting element is provided. A key sheet, and a surface of the key sheet is a high reflectance surface. 2. The operation key illumination device for a small electronic device according to claim 1, wherein the surface of the key sheet is covered with a metal foil.