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US 4,839,474 AGranted
Switches and keyboards
AssigneeKey Innovations Limited
InventorsRichard P. Hayes-Pankhurst, Brian D. Smith
Life of this patent
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AssigneeKey Innovations Limited
InventorsRichard P. Hayes-Pankhurst, Brian D. Smith
Estimating the term…
A low profile switch or keypad has one or more touch buttons of circular or polygonal shape in plan formed integrally with and raised from a surrounding membrane of elastomeric material by a wall of resiliently deformable material of thickness and angle relative to the membrane so that the wall can flex under finger pressure on the or each button without deflecting the surrounding membrane. The membrane and at least the periphery of the button are relatively thick and the wall is relatively thin so that deformation during the keystroke is localized in the wall. The length of the wall is about equal to the keystroke and is relatively small compared to the width of the touch button. The junction between the wall and the membrane is located a distance greater than the keystroke above the lower surfaces of the membrane so that the wall passes overcenter during the keystroke resulting in a change in tactile sensation. The underside of each touch button is preferably formed with a convex contact pad dimensioned in relation to the button diameter and travel and the length of wall so that the contact pad makes surface to surface contact with conductors of an underlying circuit board.
A keymat for use with a substrate or board having electrically conductive contact areas or surfaces thereon, wherein the keymat comprises a membrane of resiliently deformable material having at least one integrally formed dome key whose top surface constitutes a touch button joined to the membrane by a frusto-conical wall, and whose bottom surface has an electrically conductive contact area or surface thereon for contacting an underlying conductive surface on a substrate, for thus defining an electrical switch, and wherein:
A two-component switch comprising a keymat arranged as a cover on a substrate or board having electrically conductive contact areas or surfaces thereon, and wherein the keymat comprises a membrane of resiliently deformable material having at least one integrally formed dome key whose top surface constitutes a touch button joined to the membrane by a frusto-conical wall, and whose bottom surface has an electrically conductive contact area or surface thereon for contacting the underlying conductive surface on the substrate, thus defining an electrical switch, and wherein:
A keypad for an electrical switch, in which the keypad is adapted to overlie a substrate having at least one electrically conductive contact area thereon, said keypad comprising a membrane of resiliently deformable material having at least one frusto-conical dome-shaped key molded therein so that its top surface constitutes a touch button, the touch button being connected to the membrane by a dome wall, the thickness and angle of the or of each dome wall relative to the touch button and the membrane being such that irrespective of the angle to which the touch button tilts when depressed, the wall gives way to give a change in tactile sensation without substantially deforming the surrounding membrane or touch button, the thickness of the membrane being greater than the distance the button tilts or travels before the respective dome wall inverts, and said key having electrically conductive means on a bottom surface thereof for contact with a contact area on a substrate.
Dependencies are inferred from the claim text.