GB597421A - Improvements in or relating to piezoelectric oscillators - Google Patents

Abstract

597,421. Piezo electric vibrators. SUBMARINE SIGNAL CO. June 8, 1945, No. 14638. Convention date, July 8, 1940. [Class 40 (iv)] [Also in Group XL] A piezo-electric oscillator for transmitting and receiving compressional waves includes a longitudinally resonant vibratory element in which crystals are held between end shoulders with their mechanical axes parallel to the axis of the longitudinally vibratory element and their electric axes transverse thereto, the node of the longitudinally resonant element being between the crystal supporting end shoulders. In one construction, the resonant element may be recessed on opposite sides to form spaces with end shoulders to retain the crystals. In an alternative construction, the element may consist of an elongated member connected to two end masses whose surfaces form the shoulders to hold the crystals. In the unit illustrated, the element is held to a plate 24 by a screw 23. The bottom shoulders on the element may be omitted, in which case the plate 24 itself provides the shoulder surface to hold the crystals 19. The cross-section of the unit may be any regular polygon. Groups of units are mounted to cover the surface of a plate 9 which is supported through a thin flange 10 and a heavy periphery ring 11 from a casing 12. A gasket renders the joint watertight and the lower surface of plate 9 forms the radiating surface for the waves.