GB254033A - Improvements in electrical sound converting apparatus - Google Patents

Abstract

254,033. Peterson, C. W. April 3, 1025. Magnetic instruments; loud-speakers; diaphragms.-Loud-speakers or telephone receivers or transmitters are made with a magnet having opposed north and south poles 12a, 7<a>, Fig. 3, and at least two surrounding yokes 12b, 7<b>, an armature 10 having its middle part free to vibrate in an air gap between the poles, and its ends between and close to the yokes, and means such as a bellcrank lever 20, Fig. 2, and a rod 26 fon connecting the armature 10 to the diaphragm 6. The magnet is built up from E-shaped laminations fitted closely into side grooves in the casing 4 and further secured by insulating cover plates 9, 13. The lower part of the magnet is first assembled. Then the armature 10 is inserted with its coils 11 and resilient spacers 13<a>, ensuring a gap between the yokes and providing resilient pivots for the ends of the armature. Finally, the upper part of the magnet is put in and the whole clamped by a flat spring 14 over a pad 16. The bell-crank lever 20 is mounted. on a thin strip of vibrant metal 22, which is adjustably secured by a screw 25 over a cup-shaped depression in a support 24. The rod 26 is secured by a set-screw 27 to metal plates 28 in the middle of the diaphragm 6, which is a cone of parchment secured round its edge by a metal ring 33 over a felt washer 32. The diaphragm and the box 4 containing the magnets are carried by a frame 2, 2<a>, 5 on a stand 1, Fig. 1.