| 摘要 |
<p>The generator comprises a membrane (30) stretched between a sealing ring (39) and a contact ring (34). The contact ring (34) is supported by a printed circuit board (25) on which is arranged the control for the membrane. The sealing ring (39) is held at a predetermined tension by a thrust ring (40), said tension being produced by screwing down a cover (5), whereupon a shoulder (46) of the cover (5) is applied against a protective collar (42) externally surrounding the sealing ring. The collar (42) forms a part of the casing (1), in which a printed circuit board (25) rests on supports (38). The membrane (30) is composed of a support and insulation layer (31), a metal layer (32) and a piezoelectric layer (33). The piezoelectric layer is connected to the control by the contact ring (34) and metal layer (32) on one side and by a pressure spring (36) on the other; the control receives direct current through conductors (19, 20). As the piezoelectric element (33) is completely sealed by the support disc (31) and elastic sealing ring (39), the acoustic signal generator can be of watertight design, unlike known signal generators.</p> |
