US1238439A - Telephone for transmitting and reproducing sounds. - Google Patents

Description

I R.' RUIVIML:ERI I TELEPHONE FOR TRANSMITTING AND REPRODUCING SOUNDS. I APPLICATION FILED APR. 24. 1914.

lll lil TA BUIDOW Elmll/ILEZR, F -VVILIMILE'T'TPE, ILLINOTS.

TELEPHONE FOR TRANSMITTING AND REPRODUCING fiflmt l.

Specification of Letters Patent. Patented Aug. 2%, 1951?,

Application filed April 5%, 19M. Serial No. 834,093.

To all'whom it may concern:

Be it known that I, Rpnow RUMMLER, a citizen of the United States of America, and a resident of Wilmette, county of Cook, and State of Illinois, have invented certain new and useful Improvements in Telephones for Transmitting and Reproducing Sounds, of which the following is a specification.

This invention relates to telephones wherein a diaphragm and coil of Wire are so arranged that the coil mayhaye a direct inductive action on the diaphragm, more or less independently of the magnet, but includes means for magnetically suspending the diaphragm in a magnetic circuit which may be independent of or not coextensive with the magnetic circuit of the coil.

The main objects of the invention are to provide a telephone receiver of refined construction having great accuracy in sound reproduction and adaptability for long distance transmission. To this end the receiver is provided with a coil having a direct action on the diaphragm independently of the magnet in order that the usual iron' losses in the magnet and pole pieces may be avoided, and the device permitted to reproduce sound of any desired frequency without distortion ofthe sound due to induced currents in the electric circuit, set up by molecular vibrations occuring in the magnet, and to provide a receiver permitting the use of a permanent magnet of any desired power without subjecting the diaphragm to a magnetic pull, which would interfere with its required vibrations. Further objects of the invention are to provide a magnetic receiver in which the permanent magnet is not subject to demagnetization by a. current flowing in one direction in the coil.

An illustrative exan'iple or embodiment of this invention is shown in the accompanyin%drawings, in whichigure 1 is a plan view of a receiver constructed in accordance with this invention.

Fig. 2 is a sideelevation of the same.

Fig. 3 isa detail in section of the dia- 'phragm.

In the construction shown, an elliptical diaphragm 1 of magnetic material, such as soft iron, is shown located above a flat spiral elliptical coil of insulated wire 2, this coil being connected in any usual manner in the telephone line circuit.- The diaphragm is shown supported at its endson a permanent steel magnet 53, while the coil 2 is shown sup ported on a suitably formed plate 4 resting on and-secured to inwardly extending lugs 5 of magnet 3. Gaskets 6, shown in section, are interposed between the ends of the diaphragm and magnet 3 for the purpose of preventing any interfering sounds due to engagement or relative movement between I the diaphragm and magnet. The coil 2 is preferably coated with a dielectric of high inductive capacity adapted to cement the convolutions of the coil together and also close as muchas practicable, the air gap tive manner to any slight disturbances.

While all of the useful purposes of a magnet, as customarily employed in telephone receivers, are attained in this structure, the magnet is so arranged with respect to the coil and diaphragm as not to retard the vibration of the diaphragm by attraction, or prevent the full action of the current, carried by. the coil, on the diaphragm Without intermediate iron losses. When such losses amount approximately to one watt per cycle per pound of iron, it may be seen that they become very serious in instruments intended to produce vibrations up to and over 1,000 per second.

In telephonic work the frequency of voice currents is so high that the reactance of the coil becomes of a relatively high value when the coil has an iron core, so that there is considerable phase displacement between the voltage and the resultant current. the iron is removed from the core, the re actance of the exciting coil is reduced, resulting in clearer transmission'values.

The coil 2 may be provided with a soft iron core 7 if desired, but in that case the operation of the device is altered as the magnetic pull of the.coil is increased, say about. eighty times. The last mentioned arrangement. involving magnetic attraction between the diaphragm and the core of the When coil may be particularly useful in circumv stances wherein the iron losses in the core and its retentivity may be neglected. For

instance, when vibrations of high frequency and reproductions of great accuracy are not required. The diaphragm 1 need not be composed entirely of magnetic material but 'may be compounded with other materials 'having constituents including dielectrics,

period of vibration due to its springy char-' acter, llegardless of the sound waves, for instance as would take place if the diaphragm were made of steel. I

In the operation of the device either as a transmitter or receiver, electromagnetic induction between acoil and diaphragm takes place either by movement of the diaphragmunder sound waves or a variable ,current conducted by the coil. In each case, however, a magnet of any desired power is permitted to perform useful purposes Without involving needless reactance in the coil or interference with the desired operation from the result of molecular vibrations in the magnet which occur when it is directly connected with the core of the coil. Because of the springy character of the material of ermanent magnets, such vibrations when once setup persist for some time. and interfere witli the operation of the device.

Although but one specific embodiment of this invention has been herein shown and described, it will be understood that numerous details of the construction shown may be altered or omitted without departing. from the spirit of this invention as defined by the following claims.

I claim:

1. A device of the'class described,.com-

prising a vibratable member, a coil of Wire,-

and a magnet, said vibratable memberbeing arranged .in substantial magnetic suspension in the circuit of said magnet, said coil being so located that its magnetic circuit is not coextensive with the circuit of said magnet but includes the vibratable member therein.

2. A device of the' class described, com-,

prising a vibratable memberwithout substantial permanent magnetic qualities, a coil of wire, and a magnet, said vibratable memher being arranged in substantial magnetic suspension in the circuit of said magnet,

said coil being so located that its magnetic circuit is not coextensive with the circuit of said magnet but includes the vibratable member therein. v a

3. A device of the class described, comprising a vibratable member, a coil of Wire,

acore for said coil, and a magnet, said vibratable member being arranged in substantial magnetic suspension in the circuit of said magnet, said coil being so located that its magnetic circuit is not coextensive with the circuit of said magnet but includes the vibratable member therein. f

Signed at Chicago this 22nd day of April,v 191 I RUDQWRUMMLER.

Witnesses:

ILLIAM E; HANN, EONA SMITH.

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