Button switch

Details Button switch Button switch

2000-10-25

2001-12-04

Donovan, Lincoln (Department: 2832)

Electricity: circuit makers and breakers

Solid contact

Push button operated

C200S0050EA, C200S512000, C200S275000

Reexamination Certificate

active

06326571

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to a button switch, and more particularly to the button switch in which a rubber piece having a plurality of thin metal wires embedded therein and electrically conductive films applied to both surfaces to constitute a key button contact portion is provided on a lower face of a pushing member of the button switch.
As shown in
FIG. 6
, a conventional button switch has been composed of a key button
61
, a contact portion
62
provided on a lower face of a pushing member of this key button
61
, and contact patterns
64
printed and wired on a printed circuit board
63
. Usually, the key button
61
is made of silicone rubber
65
or the like as shown in
FIG. 7
, and an electrically conductive film
66
made of carbon or the like as the contact portion has been bonded to a lower face of the pushing member of the key button made of the silicone rubber
65
.
In the conventional key button switch provided with the contact portion employing the carbon contact or so, in case where the printed circuit board etc. acting as a portion to be contacted is free from foreign substances such as dust, oil, or flux of solder, etc. as shown in
FIG. 8
, normal switching operation can be performed by pushing the pushing member of the key button. However, in case where the foreign substances such as dust, oil, or flux of solder, etc. have been adhered to the portion to be contacted such as the printed circuit board as shown in
FIG. 9
, the contacts become inconductive, resulting in a problem of defective switching operation of the switch.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a button switch in which such defective operation of the switch due to presence of the foreign substances can be solved and stable conduction of electricity can be obtained.
According to first aspect of the invention, a button switch comprises a key button, and a key button contact portion which includes a rubber piece having a plurality of thin metal wires embedded therein and electrically conductive films applied to both surfaces of the rubber piece, the rubber piece being provided on a lower face of a pushing member of the button switch.
With this structure, the problem of defective switching operation can be solved and stable conduction of electricity can be obtained.
Further, according to second aspect of the invention, a button switch comprises a contact member provided on a lower face of a pushing member of the button switch and adapted to be pushed to conduct switching operation of contact patterns which are print-wired on a printed circuit board, in that the contact member includes a rubber piece, electrically conductive films formed on upper and lower faces of the rubber piece, and metal wires embedded in the rubber piece so as to interconnect the electrically conductive films, the contact member being bonded to the pushing member.
With this structure, the problem of defective switching operation can be solved and stable conduction of electricity can be obtained.
Further, the electrically conductive films may be made of carbon.
With this structure, the problem of defective switching operation can be solved employing the electrically conductive films made of carbon and stable conduction of electricity can be obtained.
Still further, the metal wires may be gold wires.
With this structure, favorable electrical conductivity can be realized, the problem of defective switching operation can be solved, and stable conduction of electricity can be obtained.
Still further, the rubber piece may be made of silicone rubber.
With this structure, molding can be easily conducted, the problem of defective switching operation can be solved, and stable conduction of electricity can be obtained.


REFERENCES:
patent: 3808384 (1974-04-01), Boulanger
patent: 4034176 (1977-07-01), Larson
patent: 4163138 (1979-07-01), Harden
patent: 4194105 (1980-03-01), Hodges
patent: 4527021 (1985-07-01), Morikawa et al.
patent: 4766271 (1988-08-01), Mitsuhashi et al.
patent: 4771139 (1988-09-01), DeSmet
patent: 4814561 (1989-03-01), Kawasaki
patent: 5536911 (1996-07-01), Madill
patent: 10-40771 (1998-02-01), None

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