GB595154A - Improvements in or relating to piezoelectric vibrators - Google Patents

Abstract

595,154. Sound transmitting and receiving devices. SUBMARINE SIGNAL CO. April 3, 1945. No. 8250. Convention date, April 3, 1941. [Class 40 (iv)] [Also in Group XXXVIII] A piezo-electric vibrator, particularly for producing and receiving compressional waves in submarine signalling, comprises a plurality of longitudinal vibrating units 6 supporting piezo - electric crystals on the sides thereof, the units being mounted on a plate 2 aligned by the ridges 2<1> cemented by cement 12 and secured by machine screws 11. The units are nested together in a rectangular fashion sufficiently close together to cover effectively the entire plate surface. The units are slightly tapered from the base to the top and each comprises a base element 7 and a top member 8 with two recessed sections on opposite sides wherein the crystals are firmly fixed by cementing their top, bottom, and back edges to the recess surfaces. The crystals are provided with two inner electrodes 12 and 13 which contact the surfaces 9 and 10 or are otherwise grounded to the plate 2. The external electrodes 14, 15 are connected to the bus-bar 16 by leads 17, 18. The compressional bearing surfaces are parallel to the radiating surface of the plate 2 while the electrodes are parallel to the longitudinal axis of the units. The side of the casing 1 opposite to the plate 2 is closed by the cover 23 which has a waterproof gasket 25. Fig. 3 shows one of the units in which the conductor 17 is connected to a mounting block 28, and is held by two insulating washers 29, 30, being joined to the ring 37 from which the connector 32 extends to the bus-bar 16. The back electrodes (not shown in Fig. 3) are connected by leads 33, 34 to the terminal 35 secured by the screw 36 to the unit, thus effectively grounding them. The invention is stated to be applicable to direction-finding and rangefinding by picking up echoes from distant objects.