Membrane key switch with anti-inversion feature

DETAILED DESCRIPTION The present invention relates to a matrix key switch of the membrane type wherein there are laminations of dielectric film material and plastic sheet material having selectively disposed thereon, conductive paths which form the contact points of the switch.
Included in one of the membrane layers are a stiffening means via a series of dimples arranged at each key switch site to provide an appropriate tactile feel to the key switch user.
In accordance with the invention, there is provided in the membrane that forms the dimple of the invention switch construction a series of ribs which radiate outwardly and are disposed around the periphery of each dimple to stiffen the membrane film material and preclude the buckling condition which has been discovered to lock the dimple in a downward or closed position to result in inoperability of the switch site.
Accordingly, it is an objective of the invention to provide an improved membrane switch of the type having dimples intended to provide an appropriate tactile feel to switch operation.
It is particularly an object of the invention to provide a dimpled membrane switch construction which precludes dimple inversion in use of the switch.