GB315109A - Improvements relating to sound reproducing devices, such as loud speakers - Google Patents

Abstract

315,109. Bobrovsky, I. S. July 24, 1928. Loud - speakers; magnetic instruments.-The diaphragm of a loud-speaker is impulsed by a single conductor, mounted on springs forming part of the secondary circuit of a transformer, and arranged in a magnetic air-gap. The four like poles of permanent or electro-magnets 1 - - 4, Figs. 1, 2, are joined together by a yoke 7 terminating in a pole-piece 9 of good magnetic permeability. The other like poles are joined by a similar yoke 9, and pole-pieces 10, and in the gap between the pole-pieces is supported a strip conductor 19, mounted on springs 17, 18 joined to heavy copper conductors 15, 16, which are supported by insulating blocks of the substance known under the registered Trade Mark bakelite, fibre, &c., and are connected to the secondary circuit 22, of a transformer. A member 20, attached to, or integral with the strips 19, passes through recesses in the pole-pieces 8, 10 and is connected to the apex of a conical or other diaphragm, which may form part of a cylindrical or conical enclosure, or mav work into a horn. A lever system may be interposed between the driving member and the diaphragm. In a modification, Figs. 5, 6, two magnets 31, 32 replace the four shown in Figs. 1 and 2, and the strip conductor 36 is in one piece, the ends being fastened to the ends of the transformer secondary 22, the whole apparatus forming a unitary structure. In a further modification, Figs. 8, 9, the magnet system 41 is all in one piece with an air-gap at 42, the transformer being mounted on the magnet system,