Planar contact array switch having improved ground path for dissipating electrostatic discharges

Abstract

An improved planar contact array switch having reduced susceptibility to electrostatic discharge includes a printed circuit board which carries at least one switch contact foil pair. Sandwiched between the circuit board and an insulative overlay is a dome-shaped disc which, when depressed, completes an electrical circuit between the switch contact foil pair. Bordering the periphery of the printed circuit board so as to bound the area occupied by each of the switch contact foil pair is a ground foil which advantageously is provided with at least one inwardly extending charge conductive foil which runs adjacent to each of the switch contact foil pairs for conducting any electrostatic discharge which penetrates the overlay within the area bordered by the ground foil. To facilitate the conduction of electrostatic discharges to the perimeter ground foil through the charge conductive foil, a spark gap is provided between each of the switch contact foil pairs and the charge conductive foil so that an electrostatic discharge may jump the spark gap and be conducted via the charge conductive foil on the ground plane to circuit ground.

Dependencies are inferred from the claim text.