Electricity: circuit makers and breakers – Multiple circuit control – Multiple switch
Patent
1994-03-23
1996-05-07
Scott, J. R.
Electricity: circuit makers and breakers
Multiple circuit control
Multiple switch
200 6A, 200 18, 200339, H01H 900, H01H 2500
Patent
active
055148433
ABSTRACT:
A pressure-compensated key switch that actuates when a force is applied to an individual key but does not actuate when a uniform pressure is applied to all of the keys. The pressure-compensated key switch includes at least two keys arranged approximately symmetrically about, and balanced on, a pivot. A switch mechanism actuates when a force that offsets the balance and depresses one of the keys. The uniform pressure applied equally to all the keys will not depress or actuate any of the keys. When an individual key is depressed, a pad made of conductive material contacts and bridges a gap between two electrodes to complete an electrical path. The bridging of the gap is the actuation of the switch mechanism. The pressure-compensated key switch is typically part of a system that includes an electrical device to sense completion of the electrical path. A spring returns the key to its un-depressed position when no depressing force is applied. The keys are covered by a flexible membrane that makes a waterproof seal with a housing. An optional light source may illuminate the keys from below by shining through the keys and flexible membrane. Due to its balanced design the pressure-compensated key switch may be used underwater at depths as great as hundreds of feet without being actuated by the uniform water pressure and may be used at sea level without requiring an excessive force to depress the keys.
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Gilman Dave J.
Wilfong James A.
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