GB388821A - Process and apparatus for the electromagnetic recording and reproduction of sounds by means of magnetisable wires, bands and the like - Google Patents

Abstract

388,821. Recording or reproducing sound. LIGUORI, G., 46, Georgenstrasse, Munich, Germany. Sept. 4, 1931, No. 24918. [Class 40 (ii).] Electromagnetic recording or reproduction of sound is effected by the passage of a wire, band, or like record carrier through the shunt field of a closed magnetic circuit. As shown by Fig. 1, a wire record carrier a is passed between poles 4, 5 which project from a ring-shaped magnet core 1 to provide a magnetic shunt field. Coils 2, 3 carry the sound-induced currents. According to the construction shown in Fig. 2, the core for the magnetic circuit consists of a group of plates each comprising a rectangular part 6 with an intermediate bar 7. The bars 7 are slit at 10 to allow their introduction within the coil 8 which carries the sound-induced currents. Strips 9 between the bars 7 fix the bars tightly within the coil 8 and provide magnetic poles 11, 12. The record carrier is moved past either of the poles 11, 12. Alternatively, two magnet structures as in Fig. 2 may be arranged side by side and the record carrier traversed past a pole of one and the oppositely-energized pole of the other. In order to bring the poles into contact with the record carrier during recording, and out of contact therewith during reproduction, the magnets may be mounted in the adjusting device shown by Figs. 6 and 7. The poles 21, 22 with coils 23 are arranged in rectangular' cups 24 which are slidable in carriers 25, 26 by means of micrometer screws 27, 28. The ends of each coil 23 are connected to contact plates 29, 30 which bear against springs 31, 32 connected electrically with pairs of contact pins 34, 35.