Piezoelectric key board switch

Abstract

A key board switch comprising a multi-piezoelectric polymer film element A having, in the surface of the polymer film, a plurality of piezoelectric unit elements satisfying the following criteria: (a) the unit elements have electrodes on both surfaces thereof, (b) the portions of the polymer film of the piezoelectric unit elements held between the electrodes on both surfaces have piezoelectric properties and (c) any two piezoelectric unit elements are electrically independent of each other at least with respect to electrodes on one of the surfaces; and a substrate sheet B on which the polymer film element A is laid over and having windows or recesses in the positions corresponding to each of the piezoelectric unit elements of the polymer film element A. The key board switch is adapted so that those portions of the polymer film between each of the piezoelectric unit elements in the element A are secured to the substrate B at intermediate positions between the windows or recesses in the substrate B, whereby the stress applied to one of the piezoelectric unit elements is not transmitted to other adjacent elements so that the changes in the electric field generated from each of the piezoelectric unit elements can be an independent output.

Dependencies are inferred from the claim text.