RESONANT AIR-COUPLED PIEZOELECTRIC FILM TRANSDUCERS - A DESIGN USING NETWORK METHODS

摘要

Resonant air-coupled piezoelectric film transducers have been optimised by network methods to achieve a high ultrasound pressure. For this purpose, a new network structure has been developed considering the mechanical tension and the bending strength of a statically pre-stressed vibrating plate. The examined transducers consist of a pre-stressed PVDF film, which is applied to a structured backplate with parallel and equidistant rails on top of its surface. Between neighbouring rails, the film forms a slightly curved section because of a low air pressure between film and backplate. As a result, the uniaxial piezoelectric effect is utilised to dynamically change the length of the film between the rails, which generates an acoustic volume flux.