Piezoelectric polymer film stretched over doubly-curved frame - heating it gently to slightly shrink, pref. in the presence of an electric field (NL 15.3.78)

摘要

The film is made into a transducer by stretching it, smooth and crease-free, over a curved (e.g. saddle-back-shaped) frame. This is done by fixing the film to the frame, and the warming it sufficiently to shrink it somewhat, without destroying the piezo-electric properties. The polymer film is pref. furnished with electrodes on each side before it is fixed to the frame, and the warming is pref. done in the presence of an electric field. When the method is applied to films of polyvinylidenefluoride, the temp. used is pref. 70-90 degrees C.