Electricity: circuit makers and breakers – Solid contact – Membrane type
Patent
1998-01-16
1999-02-16
Friedhofer, Michael A.
Electricity: circuit makers and breakers
Solid contact
Membrane type
200 5A, 200314, 200317, H01N 900, H01H 1370
Patent
active
058710884
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an EL sheet diaphragm for use as a lighted switch in an input control section of various electronic devices (portable devices, in particular) and a switch using the same.
BACKGROUND OF THE INVENTION
Recently, such electronic devices as communication, video and audio devices are used more and more in portable applications.
A lighted switch in conventional portable electronic devices has been lighted by employing either a bullet-type LED in the vicinity of a contact part of the switch or a chip-type LED in the vicinity of the switch, and providing such light guiding plate as transparent acrylic plate to guide the light to the switch section.
A lighted switch comprising opposing films or glasses with a transparent electrodes on a diffusion-type EL sheet is also known.
However, in such constitution of employing a chip-type LED in the vicinity of the switch, and guiding the light by means of a light guiding plate, it has been a problem that a loss of light and unevenness in brightness are significant, and an attempt of reducing the loss and unevenness causes increase in size and weight, leading to higher power consumption of LED and earlier exhaust of a battery in a portable device, so that the portable device cannot be used continuously for a long time.
A switch with transparent electrodes provided in opposition to each other on an EL sheet is advantageous in that very uniform illumination can be obtained, and a loss is insignificant, while it has been a problem that it lacks operational feeling as a switch.
Further, although a sputtered film of indium tin oxide (hereinafter ITO) is employed as a transparent electrode in a conventional diffusion-type EL sheet, because it is excessively stretched and bent in a process of shaping a diaphragm portion, it has been a problem that ITO may be relatively easily broken during the shaping process or operation of the diaphragm portion, and no light is emitted by the diaphragm portion due to breakage of a binder resin in a light emitting layer or dielectric layer.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a high-quality EL sheet diaphragm and a switch using the same such that a uniform illumination can be achieved, power consumption is reduced, a good operational feeling can be obtained, and light emission failure is reduced.
In order to achieve the object, an EL sheet diaphragm is formed by shaping a diffusion-type EL sheet that comprises a transparent electrode layer formed on a transparent film, a light emitting layer, a dielectric layer, a rear electrode layer and an insulating layer in the form of a dome with a flange-like supporting portion in an outer circumference thereof such that a light emitting surface is in a convex side, and is reversed when it is pressed for operation, and a switch is provided by using the diaphragm.
According to above constitution, a high-quality EL sheet diaphragm and a switch capable of providing uniform illumination, low power consumption and good operational feeling can be obtained.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an outer plan view of a switch using an EL sheet diaphragm according to an embodiment of the invention;
FIG. 2 is a sectional view taken along a line A-B of FIG. 1;
FIG. 3 is a view of a printed pattern in the EL sheet diaphragm;
FIG. 4 is a sectional view taken along a line C-D of FIG. 3;
FIG. 5 is a sectional view taken along a line E-F of FIG. 3;
FIG. 6 is a push-down pressure curve in relation to a compression stroke of the diaphragm portion;
FIG. 7 is an outer plan view of a switch using an EL sheet diaphragm wherein the diaphragm portion is of a multicolor light emitting type; and
FIG. 8 is a view of a printed pattern in an EL sheet diaphragm according to a second embodiment of the invention.
BEST MODE OF CARRYING OUT THE INVENTION
An EL sheet diaphragm according to an embodiment of the invention and a switch using the same are described below by referring to FIGS. 1 to 7.
(Embodiment 1)
FIG. 1 is an out
REFERENCES:
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patent: 4493958 (1985-01-01), Hamilton et al.
patent: 4532395 (1985-07-01), Zukowski
patent: 4551598 (1985-11-01), Hamilton et al.
patent: 4683360 (1987-07-01), Maser
patent: 4684353 (1987-08-01), DeSouza
patent: 4719385 (1988-01-01), Barrow et al.
patent: 4786767 (1988-11-01), Kuhlman
patent: 4882581 (1989-11-01), Inobe et al.
patent: 5557295 (1996-09-01), Miyashita et al.
Friedhofer Michael A.
Matsushita Electric Industrial Co.,Ltd.
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