PROCEDE ET DISPOSITIF POUR LA REPRODUCTION DES SIGNAUX ENREGISTRES

摘要

1355835 Pickups TELEFUNKEN PATENTVERWALTUNGS GmbH and TELDEC TELEFUNKEN DECCA SCHALLPLATTEN GmbH 14 May 1971 [15 May 1970] 15009/71 Heading H4J [Also in Division G5] In a playback arrangement comprising a pickup and a record carrier for storing signals as variable elastically compressible surface features, the pickup includes an engagement portion adapted, when the pickup is traversed over the carrier, to engage and compress the surface features of the carrier and a pressure loaded mechanical-electrical transducer element operating in the thickness mode for transducing the pressure applied to the engagement portion into electrical signals. The mechanical-electrical transducer element has a thickness in the direction of the reaction between the pickup and the record carrier, less than half the wavelength of the mechanical oscillations produced by the record carrier at the upper limit of the frequency range of the record carrier. The upper frequency limit may be 6 MHz or 4 MHz. The transducer element may be a parallelepiped, e.g. a cube. It may be of piezoelectric, magnetostrictive, piezomagnetic or of pressure sensitive semi-conductor material. The transducer element may be of ceramic material such as lead zirconate-titanate or potassium-sodium-niobate, e.g. lead zirconatetitanate of thickness 0À2 mm. Affixed to a piezoelectric ceramic body 2 (Fig. 1) by means of hard glue is a diamond skid 3 in the form of a three-edged prism. Edge 4 runs in the groove of a hill-and-dale disc and forms with the disc an acute angle of 3 to 10 degrees. Body 2 is secured by an elastic moulding 5 of soft plastics material having high internal damping to an aluminium holder 6.