GB723964A - Improvements in and relating to electromechanical transducing devices, such as gramophone pickups and the like - Google Patents

Abstract

723,964. Gramophone pick-ups. COSMOCORD, Ltd., and KELLY, S. June 15, 1951 [June 15, 1950], No. 14965/50. Class 40 (4). [Also in Group XXXVIII] A piezo-electric pick-up comprises two styli, one for standard and the other for micro-groove recordings, which are each operatively coupled to a common crystal with a different mechanical advantage appropriate to the respective reproduction characteristics. As shown in Fig. 1, a torsional-type crystal 10 supported by pads 11 has its free corner coupled by a clip 12b to an arm 12a which is pivoted at 12c and carries permanent jewel or tungsten carbide styli 15, 16 on cantilever arms 13, 14 attached to its ends. Each cantilever has low transverse and high vertical compliances and acts on the crystal through the pivoted arm and clip with different mechanical advantage. In an alternative arrangement, Fig. 2, a bender-type crystal 10a has its free end coupled to the arm by a clip coincident with the axis of the pivot, this axis being offset from the centre of the arm. A modified arrangement of Fig. 2, Fig. 3 (not shown), has the arm and clip positioned as in Fig. 1. In a cartridge assembly, Fig. 4, utilizing the arrangement shown in Fig. 2, a torsional-type crystal 21 is mounted by a rubber clamp 22 in a two-part casing 20 provided with terminal lugs 26. The free crystal end is gripped by a yoke 23 having a pivot 24 mounted in a rubber bush 25 and carrying arms 31, 32 which are bored to receive the cantilevers 27, 28. A screw 33 clamps the cantilevers which are also soldered in position. The cartridge assembly is mounted by metal brackets 35, 36 and screws 38, 39, Fig. 5, in a cradle 37 which is pivoted between the ends of a U-shaped stirrup 40. A moulded finger lever 41 enables the cradle to be rotated so that either stylus may be brought to an operative position, a detent mechanism controlled by a spring 42 being provided by a lug 37b on the cradle and co-operating lugs 40a-40d on the stirrup.