GB878935A - Reinforced hollow piezoelectric ceramic transducer structures - Google Patents

Abstract

878,935. Stereophonic pick-ups. SONOTONE CORPORATION. June 19, 1959 [July 1, 1958], No. 21178/59. Class 40 (4). [Also in Group XL (b)] Thin wall cylindrical ceramic transducers are strengthened by putting them under axial compression. The cylinders may be of circular or square cross-section (see Figs. 2 and 2A), with two diagonally opposed pairs of outer electrodes and corresponding inner electrodes or a single common inner electrode as shown. The ceramic material may be barium, lead, zirconium, titanates or niobates. As applied to a stereophonic pick-up for 45-45 cut records the cylinder is mounted at one end in a rubber block 45 inside a tubular plastic housing 42, Fig. 1. The end of the cylinder bears against a neoprene washer 27 with a metal backing pad 28 against which bears a steel cylinder 32-1 in the bore of which a wire 32 is secured. Wire 32 may be of stainless steel, phosphor bronze, or beryllium copper, and passes through the centre of the ceramic transducer to its far end where it is tensioned by a screw and nut connection to compress the transducer wall axially. A synthetic plastic sleeve washer 29 covers the far end of the transducer and provides a surface to which is cemented a synthetic plastic stylus arm 37 carrying alternative styli 15. The space between the wire 32 and the ceramic cylinder 21 is filled with a damping liquid such as silicone oil. The rear of the pick-up cartridge is plugged by a nylon bush 38 through which pass four strip terminals 36 which are clamped against the electrodes of ceramic cylinder 21 by the rubber mounting 45. To mount the cartridge detachably in a tone arm the metal work of Fig. 7 is employed. The plastic cartridge case 42 has a cylindrical portion engageable by a clip 73 secured by lugs bent over in slots 74 to a carriage 80. The carriage 80 is fastened to the tone arm (not shown) and has an indent 88 co-operating with diametrally opposite indents 55 in the cartridge casing 42 to define the positions in which the alternative styli are set in place when the cartridge is rotated by an arm 51. These positions are further defined by abutment of the arm with down-turned wings 87 on the carriage 80.