GB437605A - Electrodynamic sound reproducers or microphones - Google Patents

Abstract

437,605. Sound-reproducing devices. PRICE, S. L., 185, King's Avenue, Clapham Park, and PARRITT, J. E. G., 69, Mark Lane, both in London. April 27, 1934, No. 12820. [Class 40 (iv)] A microphone or loudspeaker comprises a moving conductor or winding carried by a conical diaphragm which forms its sole support, the conductor being capable of movement in more than one direction, in a gap formed by vertical plane surfaces of a permanent magnet or an electromagnet. There may be more than one conductor gap or diaphragm. As shown in Fig. 3, a flat coil is pivotally mounted by a spindle 17 in a stirrup 19 connected to the diaphragm. A ball joint may be used between the diaphragm and the coil former. Different coils may be fitted into the stirrup, or in a modification, Figs. 8-10 (not shown), a set of windings may be mounted in a supporting frame so that any one can be turned into the operative position in which the stirrup supports it in the magnetic field. As shown in Figs. 11 and 12, two coils are wound on one former 43, which can be reversed in the stirrup 40 carried by the diaphragm, the connections being made by spring contacts 41, 42; in modifications not shown, more than two coils are mounted on one former, the coils being arranged about the sides of a triangle, square or polygon. The connection between the stirrup and the diaphragm may be adjustable in length. The instrument shown in plan in Fig. 4 comprises a permanent magnet 1 with two gaps in which move two opposite sides 10 of a rectangular coil which surrounds the central pole and is guided by a central rib 17 which extends into a groove in the magnet. The former 6<1> is connected to the diaphragm 7 by a rod 16 jointed at 20. In a modification, Fig. 6, the rectangular coil is replaced by a pair of flat coils 6, 6, pivotally mounted by means of spindles 17 between arms 28 in a stirrup 19. In another construction, Fig. 1 (not shown), a flat coil moves within a single gap formed by an adjustable polepiece. As shown in Fig. 7, two opposite parts 10, 101 of a single flat coil move in the gaps between two magnets 30, 31. The former 6 is connected with the diaphragm 7 by a rod 16 adjustable in a sleeve 32. A second conical diaphragm (not shown), having different characteristics may be carried at the free end of the former.