US 1743011 A
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Jan. 7, 1930. ZIMMERMAN 1,743,011
SPEECH CURRENT APPARATUS Filed Feb. 14, 1928 Inventor- Arthur GZim'mePman 9 w Hi2; Afiohh eg Patented Jan. 7, 1930 UNITED STATES Parser-onion ARTHUR, G. ZI-MMERMAN, or scnnnncrnnr, new YORK, ASSIGNOR 13o GENERAL ELEC- 'rnro COMPANY, A oonronmnon or NEWYYORK SPEECH-CURRENT APPARATUS Application filed February 14, 1928. Serial No. 254,296. I
My invention relates to speech current generators and motors, and has for its principal object the provision of an improved apparatus which may be eficiently operated either to convert speech current into sound or to generate electric current which is dependent on sound,
Various types of speech current have been provided in the past. Many of these apparatus include a coil which is mounted on a diaphragm and is arranged to move in a magnetic field either in response to speech current supplied to the coil or in response to sound impulses applied to the diaphragm. 1
As pointed out in Patent No; 1,?07,570, issued April 2, 1929, to Chester W. Rice, and assigned to the same assignee as the present application, apparatus may be improved by the provision of conductive rings of copper or similar low resistance materials embedded in the pole pieces of the magnet through which the magnetic field surrounding the movable coil is: produced. With this construction, the con ductive rings embedded in the pole pieces form low resistance secondary circuits which reduce the reactive component oi the diaphragm coil impedance and increase the op erating efiiciency of theapparatus. In ac- ,cordance with my invention, is further increased by making the conductive rings in the form of layers of conductive material which are rolled, electroplated orotherg wise placed on the active surfaces of the pole pieces. This arrangement of the conductive rings has the important advantage that it perm-its very close coupling between these rings and the movable diaphragmcoil, thusgreatly decreasing the inductance of the movable coil.
My invention will be better.understood from the following description when considered in connection with the accompanying drawings and its scope will be pointed out in the appended claims. v
. Referring to the drawings, Fig, I-is asec- 'tional view of a speechcurrent apparatus wherein my invention has been embodied,
apparatus the operating efficiency of such this efiiciency and Figs. 2 and 3 illustrate various details of the pole pieces oi this apparatus.
This apparatus includes a coil 4 which is mounted on a diaphragm 5 and is arranged to move between the pole pieces 6 and 7 of a m'agnet shown as'provided with a field or excitlngcoil' 8. As shown more clearly in X is provided Figs. 2 and 3, the [pole piece 6 with a copper lining 9 and the pole piece 7 is provided with a copper covering 10.
It will be readily understood that the conductive coverings 9 and 10 may be made very thin and may extend somewhat beyond the active areas of the pole pieces so that the flux of the magnet is highly concentrated in the path of the moving'diaphragm coil 4. Under these conditions, the apparatus has been found to operate very efficiently when utilized to convert speech current into sound or vice versa. :While both the pole pieces have been shown as" provided with a C0111 ductive covering, it should be understood that similar results may be secured by increasing the thickness of one of the coatings and omitting the other coating.
pair of magnetic pole-pieces, layers of con- 'ductive material arranged to cover the active areas of both of said pole pieces, a diaphragm, and a coil mounted on said'diaphragm and arranged to move between said layers of conductive material. r
2. A speech current apparatus including a pair of magnetic pole pieces, layers of nonmagnetic conductive material arranged to cover the active areas of both of said pole pieces, a diaphragm, and a .coil mounted on said diaphragmandarranged to move between said layers ofnon-magnetic' conductive materiah' 3.. A speech current apparatus including a pair of magnetic pole pieces, layers of copper arranged to cover \the active areas of both of said pole pieces, a diaphragm, and a coil mounted on said diaphragm and arranged to p move between said layers of copper.
' 4. A speech current apparatus including a pair of magnetic pole pieces, the active area of one of said pole pieces being electro-plated whereby it is covered with a thin 1a. er of conductive, material, a diaphragm, an a coil mounted on said diaphragm and arranged to move between said pole pieces.
In witness whereof, I have hereunto set my hand this 13th day of February, 1928.
ARTHUR G. ZIMNIERMAN.