Output circuit for piezoelectric polymer pressure sensor

Abstract

A pressure sensitive apparatus for producing electrical signals on two electrodes having a layered structure consisting of a conductive layer, a piezoelectric polymer film layer, an electrode layer, an insulating layer, another electrode layer, another piezoelectric polymer film layer, and another conductive layer. The layered structure may be constructed from an insulating layer sandwiched between two piezoelectric polymer films each having an electrode on one surface thereof and having a conductive plane on the other surface thereof disposed on each side of the insulating layer with the electrodes in closest proximity to the insulating film. Further, support substrates may be disposed on each side of the piezoelectric polymer films, the support substrates having an opening where the electrodes are located. Still, further, the apparatus may be adapted for a pressure sensitive matrix keyboard having a plurality of keyboard switch positions arranged in a plurality of rows and columns where the electrodes are a strip constituting one of the rows and columns, respectively, of the keyboard switch positions. The piezoelectric polymer film may be polyvinylidene fluoride and the layered structure may be integrally bonded or physically sandwiched together and may have connected to it an electrical sensing circuit suitable for amplifying a small charge pulse induced by the strain upon the piezoelectric polymer film.