COMPOSITE ACOUSTIC SYSTEM FOR TELEPHONE HAND-SETS

摘要

The aim of the invention is to utilize the advantages of plane piezo-electric oscillators for telephone hand-sets, at the same time avoiding their disadvantages. The proposed plastics film substrate (12) has conductor tracks between the acoustic transducers and is fitted with contacting elements. In the zone designed as an acoustic diaphragm (2), it has, as a special feature, radial corrugations (5) which are soft-mounted between the filter unit (1) and the contact unit (6). The channels thus formed link the inner cavity under the acoustic diaphragm (2) with an edge cavity (4) in the filter unit (1). The acoustic mass action of these channels, together with the acoustic resilience of the edge cavity (4), produces Helmholtz resonance. The 180 DEG -out-of-phase oscillations produced in the acoustic diaphragm (2) effectively damp out interfering resonance peaks. The new composite acoustic system is particularly suitable for telephone hand-sets.