In a metering pulse generator, a metering element engages a spring member to effect a gradual bending movement in one direction followed by a rapid return movement during which a pulse signal is developed by a piezoelectric material on the spring member . Energy is absorbed during each such rapid return...http://www.google.fr/patents/US4868566?utm_source=gb-gplus-shareBrevet US4868566 - Flexible piezoelectric switch activated metering pulse generators
