Abstract: A matrix switch comprises a lamination of several layers in which first and second piezoelectric films have row and column electrodes, respectively, arranged in parallel on their first surfaces. A ground electrode is between said row and column electrodes. The operating electrodes are at cross points which are deformable to result in two piezoelectric output signals from each cross point; one between ground and an operating row electrode, and the other between ground and an operating column electrode.

Abstract: Separate polarizing electrodes are attached to the opposite surfaces of a thermoplastic film. A high D. C. voltage is then applied across these electrodes to polarize the film to produce an electric element, such as an electret, piezoelectric or pyroelectric element. Portions of the polarizing electrodes are then selectively removed to form the operating electrodes required for the electric element.

Abstract: A method of measuring the mechanical vibration of an object comprising contacting one of the surfaces of a piezoelectric element comprising a polarization treated polyvinylidene fluoride piezoelectric film having metal thin films as electrodes deposited on both surfaces thereof with an object to be measured while covering the opposite surface of the piezoelectric element contacting with the object to be measured with a flexible sound absorbing material for avoiding interference with sound waves in the surroundings and measuring or detecting the vibration of the object by the changes in the electric field caused by the vibration of the object and produced on the surface of the piezoelectric element.

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.

Abstract: Patterns described with inks or colors on the surface of thermoplastic resin articles having an interconnected fine open-cell structure in the surface layer thereof are rendered durable without displacement or deformation by heating under pressure the pattern described surface to a higher temperature than that at which said thermoplastic resin becomes fluid to cover the pattern-bearing surface with a thin film formed from the original resin constituting said surface layer.