Piezoelectric polymer keyboard apparatus

Claim 1

In a keyboard switch including a pair of poled piezoelectric films having metallic electrodes disposed thereon, said switch comprising a pair of electrically insulating substrates having a plurality of spaced identical cut-out openings in each, said pair of poled piezoelectric films each having a plurality of ground electrodes deposited on one surface thereof and a plurality of signal generating key electrodes deposited over other surface, each of said substrates having one of said grounded electrode surfaces adhered thereto over said openings, said key electrodes and ground electrodes being in substantial registration with openings in substrate associated therewith, said key electrodes having leads connecting individual rows on one piezoelectric film disposed orthogonally to leads connecting individual columns on other of said piezoelectric film, an insulating sheet disposed between said piezoelectric films, said films having their key electrode surfaces in face-to-face relationship, the improvement to said switch comprising: said ground electrodes and said key electrodes having thicknesses ranging between about 5 to 7 microns and comprised of finely divided electrically conductive metal embedded in a polymer matrix whereby said electrodes and polymer film may be successfully deflected and strained millions of times.