US1425183A - Transmitter - Google Patents

Description

Patented Aug. 8, 1922.

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THOMAS A. EDISON, F LLEWELLYN PARK, WEST ORANGE, NEW JEY.

TRANSMITTER.

Specification of Letters Patent.

Patented Aug. d, 1922.

To all whom it may concern:

Be it known that I, THoMAsA. EDISON, a citizen of the United States, and aresident of Llewellyn Park, West Orange, Essex County, New Jersey, have invented certain new and useful Improvements in Transmitters, of which the following is a description.

My invention ,relates to transmitters, and more particularly to microphone transmitters wherein the desired variations in current are produced by variations in electrical resistance caused by varying the pressure upon a quantity of granular conductive material, such as carbon, which is disposed be tween electrodes in the circuit carrying the current, preferably in Va somewhat loose state, the requisite changes in pressure be ing efiected between the electrodes and the granular material by a diaphragm or other means adapted to be set into vibration b the sound waves from a source of soun such as the human voice.

Practically all microphone transmitters of this type such as are now used are seriously and adversely affected by phenomena extraneous to the sounds which the same are designed to transmit, such for example,.as

' shocks, jars, vibrations, concussions, etc. oc-

curring in the neighborhood thereof, these phenomena often causing such relative movement of the conductive granules disposed between the electrodes of the microphone transmitter as to produce extraneous or foreign sounds loud enough when amplified to practically obliterate and render .it impossible to understand or detect the sounds which the microphone is intended powerful amplifying devices, such as the tion will be hereinafter more fully deto transmit.

The principal object of my invention is audion, with the transmitter.

More specifically described, my invention consists in supporting a microphone transmitter entirely by a mass or masses of resilia ent material, preferablythe material known by the trade name rubber sponge The mounting of the transmitter in this manner prevents a majority of all of the stresses,

jars, etc. of the building, vehicle or other structure in which the microphone may be located from being communicated thereto and the production thereby of any appreciable internal movements in the mass of conductive granules or fine particles. The invention also consists in making still further provision against the production of internal movements in the mass of conductive ,granules of the microphone by jars, etc., preferably by filling the space between-the electrodes in which these granules are disposed with a very light hydrocarbon oil, preferably pure distilled motor gasolenehaving a very low boiling point whereby the loose mass of granules or fine particles of conductive material will be completely immersed therein. The effect of this liquid is to dampen the movement of the conductive granules and probably hold them in closer contact. Thisliquid also acts by its buoyancy to lighten the pressure of the granules on each other. I find that the sensitiveness of the microphone to the sounds which it is desired to transmit thereby and which are communicated to the main diaphragm of the microphone by the air or other fluid in which the latter is-disposed, is but ver slightly diminished by the use of the liqui while internal movements of the mass of conductive granules or fine particles by jars, etc. occurring in the vicinity of the microphone, and thereby the production of jar or like extraneous sounds in the microphone, are practically eliminated. A microphon apparatus in which the features just described are combined is extremely efli'cient, as it is possible to transmit thereby very clearly and distinctly, sounds of the weakest character as well as loud sounds; my improved .mircrophonic apparatus being especially adapted for the transmission of oral communications, as the articulation and distinctness of such communications transmitted thereby are greatly increased.

Other objects and features of my inven- 40 Y 1 ed thereon. A hollow neck 13 extends cen-' .tire support for the" microphone, and prevents-nearly all. jars,etc. to Which the base is subjected from being communicated to the transmitter.

The microphone casing consists of ametallic sound box 4 having an arched body porvmounted on the said seat.

tion from which extends an annular flange 5, and a cover 6 provided with a peripheral flange the endjportion of which surrounds the flange 5 and is detachably secured thereto in any suitable manner. The sound box 4 is provided with an annular seat 7 about the arched body portion thereof, and a metallic diaphragm 8, is suitably secured against an annular shellaced fabric ring 9 The peripheral edge portion of the diaphragm 8 preferably has applied thereto a ring 10 formed of rubber or other suitable yielding material, covering both faces of such edge portion, and the diaphragm is preferably held to its seat by means 0 a plurality of leaf springs 11 secured at one end tolthe annular flange 5 of the sound box and bearing attheir free ends on the rubber ring 10, said free ends preferably having sleeves 12 of soft rubber or other suitable yielding material mounttrally from the base of the sound box 4 and 'is adapted to have a; horn or other suitable receiver secured thereto by means of which the sound waves from the person speaking, or other source of sound, are caused to converge into thesound box body. and set the diaphragm 8 into vibration. A bridge 15 extends diametrically across the sound box body and has its ends suitably secured to the annular flange 5 as by means of screws; 16, the central portion of this bridge being provided with a U-shaped ortion 17 extending tdwards the cover 6. eference character 18 represents a cylindrical bearing member or sleeve which extends through an opening in the center of the cover 6 in line wlth the hollow neck 13 of the sound box 4, the outer end of said sleeve being provided with an annular flange 19 and the inner end thereof being provided with a redu d cylindrical portion 20 which extends through an opening provided in the center of the U-shaped pdrtion" 17 of bridge 15. The inner end of the reduced portion 20 of'the sleeve 18 has a nut 21 threaded thereon, whereby the sleeve 18 is rigidly secured to the bridge 15.

An arm 22 constituting a contact member is mounted on the reduced end portion'20 of sleeve 18 between the shoulder. provided by such reduced portion and the base of the U- shaped portion 17 of bridge 15, and suitable insulation 23 separates the base of the U- shaped portion 17 from the arm or contact member 22, the sleeve 18 and the 'nut 21.

A cylindrical rod or stem 24 is slidably mounted in and extends through the bearin member or sleeve 18, rotary movement 0 this rod being prevented by means of a pin 25 secured to the sleeve 18 and projecting into a longitudinal slot 26 formed in the rod. The inner end of rod 24. has rigidly secured thereto and preferablyv formed integrally therewith a'cup-shaped member 27 which constitutes areceptacle or chamber in which a pair of spaced electrodes E and a mass of conductive granules or very fine particles 28, preferably of carbon, are disposed. The end of thischamber is closed by a mica diaphragm 29 which is held in place by a ring 30 threaded on the cu -shaped member 27. The spaced electrodes l) of the transmitter arerespectively disposed between the mass of conductive granules 28 and the diaphragm 29 and the base of member 27. A small conical metallic member 31 is disposed between the diaphragms 8 and 29 and is pro-' vided at one end with a metallic button 32 which extends through and is rigidly connected with the diaphragm 8 at the center thereof, and is suitably mechanically and electrically connected at its other end with the diaphragm29.

the electrode E adjacent A quantity of liquid L, such as a light hydrocarbon oil, preferably pure distilled motor gasolene having a very low boiling point, is inserted in the cup-shaped member or receptacle 27 with the granular carbon 28, a sufficient volume of such li uid preferably being employed to substantially fill all the space in such receptacle between the electrodes E not occupied by the loose mass of fine particles of carbon. .It will thus be apparent that the loose mass of fine particles or granules of carbon is completely immersed in the light hydrocarbon oil. The results arisin from the use of this liquid have already -been fully described. A disc 33 having a knurled head 34 is threaded on the outer end of the rod or stem 24 and bears against the outer face of the, flange 19 of the sleeve or bearing member 18.x A mem-.

ber 35 is secured 'at one'end to the flange 19, as by a screw 36, and the other end thereof is provided with a finger 37 which projects into an annular groove 38 formed in the disc 33, whereby movement of the latter axially of the member or sleeve 18 is prevented. It

willl thus' be see n that the turning of disc 33 will effect sliding movement of the" rod or stem 24 in the sleeve 18, and therefore movement of the cup-shaped member or receptacle 27 axially of the microphone casing. As the member 31 connects the diaphragm 29 and adjacentnelectrode E with the diaphragm 8mounted on the soundbox 4, it will be seen that such movement of the member 27 may be utilized for the adjustment of the initial pressure on the mass'of granular carbon 28 to suit varying conditions of use. The face of the disc 33 is preferably provided with a scale or graduations 39 with which a suitable index or pointer 41, formed on the end-of a member 40 se'-' cured to the flange 19, co-operates-to facilitate such adjustment.

A. contact member 42 is suitably secured to the bridge 15 and separated therefrom by suitable insulation 43, and a flexible conductor 44 connects this contact member with the conical metallic member 31. Conductors 45 and 46 respectively connected to the contact members 22 and 42, as by binding screws 47 and 48, extend from the microphone through a suitable opening 49 in the cover 6 for connection in the circuit.

The path of the circuit through the mi- 'crophone is as follows: From the conductor 45 through contact member 22, sleeve 18, rod 24, to the base of the cup-shaped member 27 and the adjacent electrode E, then through the granular carbon 28, the other electrode E,member 31, conductor 44, contact member 42, to the other conductor 46.

While I have shown the preferred embodiment of my invention, it is to be understood that the same is subject to numerous changes. and modifications without any departure from the spirit of the invention and the scope of the appended claims. 7

Having now described my invention, what I claim as new and desire to protect by Letters Patent is as follows 1. A microphone transmitter comprising a pair of spaced electrodes, and a loose mass of fine particles or granules of conductive material wholly immersed in a single liquid between said electrodes, substantially as described.

of October, 1918.

2. A microphone transmitter comprising a air of spaced electrodes, and a loose mass 0 fine particles or granules of conductive material wholly immersed in aliquid hydrocarbon between .said electrodes, substantially as described.

3. A microphone transmitter comprising a pair of spaced electrodes, and a loose mass of fine particles or granules of conductive material wholly immersed in gasolene between said electrodes, substantially as described.

4. A. microphone transmitter comprising a fluid-tight receptacle filled with a single liquid and carrying a pair of spaced electrodes, and a loose mass'of fine particles or granules of conductive material wholly immersed in said liquid between said electrodes, substantially as described.

5. A microphone transmitter comprising a fluid-tight receptacle filled with a liquid hydro-carbon and carrying a pair of spaced electrodes, and a loose mass of fine particles or granules of conductive material wholly immersed in said liquid between said electrodes, substantially as described.

6. In combination, a microphone transmitter comprising a pair of spaced electrodes and a loose mass of fine particles or granules of conductive material wholly immersed in a single liquid between saidelectrodes, and a large mass of rubber sponget in which said microphone transmitter is mounted and by which it is wholly and directly supported, substantially as described.

7 In combination, a microphone transmitter comprising a pair of spaced electrodes and a loose mass of fine particles or granules of conductive material wholly immersed in a body or liquid hydro-carbon between said electrodes, and a large mass of rubber like material in which said micro-.

phone'transmitter is mounted and by which it is wholly and directly supported, substantially as described.

This specification signed this 23rd day rnos. a. unison;

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