| 摘要 |
1,249,464. Piezo-electric transducers. PLESSEY CO. Ltd. 4 Nov., 1968 [8 Nov., 1967], No. 50825/67. Heading H4J. [Also in Division H2] A piezo-electric transucer for subaqueous signalling comprises a metal plate diaphragm 7 with a ceramic piezo-electric wafer 5 bonded to it to form one electrode and a metal coating 6 forming the other electrode of the transducer. The diaphragm forms the base of a cylindrical cup-shaped structure having a side wall 8 with an annular groove 9. Longitudinal slits 10 are provided in the side wall to impart resilience to the diaphragm and the assembly fits into shell members 11, 12 and is secured by screws. A sealing gasket may be provided in groove 9 and a similar assembly provided at the other end of the shell members. For deep water applications, the ceramic disc may be bonded to the outer surface of the diaphragm so that it is in compression. - In a modification, the casing vibration is reduced by making the mass of the support structure large in comparison to that of the diaphragm by providing a solid centre portion to which collars are attached for fixing the diaphragm assembly. |
