GB269561A - Improvements in loud speakers and telephone receivers - Google Patents

Abstract

269,561. Schutzler, G. April 19, 1926, [Convention date]. Magnetic instruments. -Relates to a loudspeaker or telephone receiver, the magnetic poles p<1>, p<2> of which have a common axis and are disposed one on each side of a reed or diaphragm m and consists in an arrangement according to which the direct flux which runs from pole to pole passes perpendicularly through the reed in two separate portions of different specific densities and parallel to each other, one portion running inside and the other outside the speech current coil or coils, the axis or axes of the coil being parallel to the axes of the pole pieces, so that even when the section of the reed is very thin, the alternating speech flux passing lengthwise of the reed is not interfered with by supersaturation of the reed by the direct lines of force. Fig. 1 shows a construction in which the pole faces p<1>, p<2> carry two coils, the continuous flux flowing through the pole faces and reed m being divided into two parts, the flux a of greater specific density flowing through the surface pieces f and the flux a<1> of lower specific density flowing through the surface pieces f<2>. The magnetic flux b produced by the speech currents in the coils transverses only that part of the reed m adjacent to the respective coil and one of the magnet poles. The coils are connected up so that those on one side of the reed produce magnetic fields acting in the opposite direction to those produced at the same time by the coils on the other side. The reed, which is shown in section, is clamped at one end (not shown) and connected at a point intermediate its length to a cone or flat diaphragm. Other constructions are described and illustrated in which only one coil is employed. Modifications are also described and illustrated in which the flux a flows through the coil whilst the flux a<1> passes round it. Instead of having air in the magnetic gaps, other materials with less permeability than iron, such as nickel steel, ironpowder &c. may be employed.