The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 07, 1996
Filed:
Mar. 23, 1994
James A Wilfong, San Carlos, CA (US);
Dave J Gilman, San Francisco, CA (US);
Other;
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.