GB703275A - Improvements in electrical sound recording apparatus - Google Patents

Abstract

703,275. Phonographic recorders. SYKES, A. F. April 8, 1952 [March 6, 1951], No. 5412/51. Addition to 650,769. Class 40 (4) The parent Specification relates to sound recording apparatus comprising a pair of magneto-strictive rods adapted to contract and expand in anti-phase, the one pair of ends being anchored to a structure while the other ends are in close proximity and drive a stylus carrier. The present invention is characterised in that the magnetostrictive cores are slotted and the free ends operate a lever driving the stylus. The magneto-strictive rods 10, 10a are anchored at 1 to an inertia block 12 free to swing about axis 24 with respect to a feed carriage or tone arm. The free ends of the rods carry cappings 4 which transmit the anti-phase vibrations through rods 15 to a stylus lever 18 mounted in a spring- pressed swinging gate 5. The free ends of the rods ride on rollers 136 against which they are pressed by springs 2. The free ends of the rods are provided at 19 with very fine air-gaps and to prevent saturation of the cores near the base; they may be made wedge-shaped. For hill-and-dale recording, the cappings may be offset as in Fig. VI to give a vertical oscillation to the stylus. The depth of cut may be varied by adjustment of the height of ball 30. The stylus may be mounted on a hole, vee and plane method, Fig. IV, or may be operated through a compound lever system, Fig. VII. Specifications 650,808, 650,809 and 686,777, [Group XXXIV], are referred to.