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US 4,634,818 AGranted
Switches and keyboards
AssigneeNPM International
InventorsRichard P. Hayes-Pankhurst, Brian D. Smith
Life of this patent
Estimating the term…
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AssigneeNPM International
InventorsRichard P. Hayes-Pankhurst, Brian D. Smith
Estimating the term…
A low profile switch or keypad has one or more touch pads (14) formed integrally with and raised from a surrounding membrane or key mat (15) of elastomeric material by a wall (30) of resiliently deformable material of thickness and angle relative to the mat (15) so that the wall (30) can flex under finger pressure on the or each pad (14) without deflecting the surrounding membrane. The underside of each pad (14) is formed with a convex contact pad (29) dimensioned in relation to the pad diameter and travel and the length of wall (30) so that the pad (29) makes surface to surface contact with conductors (12), (13) of an underlying circuit board (10). The mat (15) is held in tension to the board (10) fits. The keyboard uses only two interfitting parts and needs no bezel but provides a tactile response to key depression.
A keypad consisting of a combined cover and membrane (15) of resiliently deformable material and a substrate (10) bearing open-circuit conductors (12, 13) against which substrate (10) of the combined cover and membrane (15) is positioned with otherwise unsupported integral touch pads (14) disposed in an array and each raised from the surrounding membrane (15) by an angled wall (30) arranged so that finger pressure on any touch pad (14) depresses it until a conductive surface (29) on the underside of the touch pad (14) contacts the substrate (10) and makes the circuit between the conductors (12, 13), characterized in that:
A keypad according to any preceding claim, wherein the membrane (15) is moulded slightly under the size of the substrate (10) and has a peripheral lip (16) into which edges of the substrate (10) locate to maintain the membrane (15) in position against the substrate (10) and to tension the membrane (15).
A two component keypad consisting of a combined cover and membrane (15) of resiliently deformable material and a substrate (10) bearing open-circuit conductors (12, 13) against which substrate (10) of the combined cover and membrane (15) is positioned with otherwise unsupported integral touch pads (14) disposed in an array and each raised from the surrounding membrane (15) by an angled wall (30) arranged so that finger pressure on any touch pad (14) depresses it to contact the substrate (10) and makes the circuit between the conductors (12, 13), characterized in that:
A keypad consisting of a circuit-bearing substrate and a membrane of resiliently deformable material having a plurality of raised dome keys moulded therein each defined by a dome wall and a touch pad at the top of the wall, the gap between the substrate and a conductive undersurface of each integral touch pad being no greater than the thickness of the membrane, and the thickness and angle of each dome wall relative to the touch pad and the membrane being such that irrespective of the angle to which the touch pad tilts the wall gives way to give a change in tactile sensation immediately before contact is made.
Dependencies are inferred from the claim text.