Membrane type touch panel employing piezoresistant anti-short means

Claim 1

A transparent switch matrix to be carried on the face of a rigid insulator substrate having a predetermined radius of curvature, and comprising: a. a plurality of spaced apart transparent conductive first strips firmly adhering to the face of the substrate; b. a transparent resilient membrane having an undistorted contour substantially alike the predetermined contour, and attached about its periphery to the face of the substrate in a position matching the membrane contour to the substrate contour and spaced apart from the first strips thereon in a predetermined area of the membrane; c. a plurality of transparent, flexible, spaced apart conductive second strips firmly adhering to the resilient membrane surface facing the substrate, each of said second strips located in the area spaced apart from the first strips and thinner than the spacing therefrom, and each of said second strips crossing at least two first strips; and d. a piezoresistant coating interposed between the first and second strips, and permitting electrical conduction between a first and second strip responsive to manual pressure at their crossover area.