Transducer for conversion of acoustic signals to electric - has piezoelectric element of film or foil in protected space fixed to metallic membrane

摘要

The transducer housing (1) is sealed by a cover (2) which has a number of openings for the transmission of sound. A membrane (4) preferably of metal is held by the bearing rings (5, 6), whose construction allows a bending movement of this membrane. A space (7) is enclosed by this membrane, the volume being suited to the acoustic properties of the transducer. In this space (7), is a foil (8) with piezoelectric qualities e.g. polyvinylfluoride, having metallised surfaces to or from which, a voltage can be conducted. On vibration of the membrane (4) by sounds, a thrust is transmitted to the foil through the support members (9, 10), resulting in the production of an electrical potential. Likewise, an electric signal can be connected to the foil. No intermediate substance is required between membrane (4) and foil (8), resulting in long term temperature stability and better acoustic qualities.