US385956A - Electric telephone - Google Patents

Description

(No Model.)

-N. PARKS.

. 4 ELECTRIC TELEPHONE. No. 385,956 Patented July 10, 1888.

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NATHANIEL PARKS, OF DEANSVILLE, NEWYORK.

ELECTRIC TELEPQHOINE.

SPECIFICATION forming part0! Letters Patent No. 385.9 56, dated July 1o, 1 838.

A ppiiratiou filed April 20. 1888. Serial K01271281- (No model.)

1'0 aZZ whom it may concern.-

lle itknown that I, NATHANIEL Plums, a citizen of the United States, residing in Deansville, in the eounty'of Oneida, in the State of New York, have invented certain new and useful Improvements in Electric Telephones,

of. which the following is a specification.

The invention relates to the class of elcctrical apparatus employed for transmitting and receiving vocal sounds.

' The object ofthe invention is to provide instruments which will cause the required variation in the strengthof an electric current under the influence of sound-waves or air-vibratlOUS,-'il6t ilCl of great or small amplitude,and which will convert such variations or electricalundulations into vibrations corresponding to the original sound-wavcs with as little loss of energy as possible.

Heretofore it has been customary to occasion the undulatiousin the electric current by causing it to traverse an artificial resistance, the

valucof-which is increased and diminished by and in accordance with the sound-waves. To

accomplish this two electrodes are connected in the circuit and held against each other in such manner that their pressure and consequent resistance may be varied through the instrumentality of the sound-waves. When the sound-waves are very light, the variation in the pressure is correspomlinglysmall, and when the waves are caused by sounds which are too loud the electrodes are thrown'apart and a consequent mutilation of the electric undulation is caused, since the ilow of the current 'is -niomenl: :ily interrupted. The present invention aims to remove this defect and provide an instrument which will operate perfectly whether the sound waves be light or heavy.

In general terms, the in\-'cntion may be stated to consist in'mounting upon a diaphragm or other body responding to-the sound-wavesan electrode which extends in a direction a right angles to its direction of movement and passes between two other clectrmles, one of which is connected directly with the source of elec trieity,while the other is connected wit-h the same source through an artificial resistance.

. The central electrode is connected with the ance offered by 'thetwo branch circuits will be varied, the resistance'of one branch being increased as that of the other is diminished. At one limit of its vibration the circuitof the battery will be for the most part or-entirely through the branch containing no artificial resistance. and therefore the current will flow freely, since the pressure upon the corresponding electrode will be suffieientr-to' canse very good electrical connection. Attire-other;

limit of vibration, however, the resistance of this circuit is increased, or its connections may be entirely interrupted; butthe circuit remains through the branch containingnthe artificial resistance, thus allowing. a' cor-respondingly small current'to flow. a k

The receivinginstrument mayrwith advan-' tage be constructed with ai -inductorinmof which the primary coil is included inthecircuit of the battery and wound upon a softiron core, to which the receiving-diaphragm is applied. The secondary coil leads'to the the main line.- The current throughthe pri- --mary coil will magnetize the core,"and thus dispense with the necessity of employing a permanent'magnet, and from this construction certain advantages, hereinafter pointed out, may be derived. V I f.

The accompanying drawing is a transverse section of thetrznismitter and the receiver,

showing the circuit-connections in diagram Referring to the figure, A'represents the'case of the transmitter. In the frontot'the case there is formed an opening, I), and beneath this tlierejis' placed the diaphragm B, which may be of anywe]l.-k.no,wnconstruction. -Upon the diaphragm, preferably-at or uear'itscenter, there is pl'a'ced'an electrode, 0, whichis hcre'shown. as projecting from the diaphragm at right angles and having its end turnedat w an angle and passing between twoelectrodes, G and G. The central electrode-may be of metal and the outer electrodes of 'earbo'n,'or other suitable. materials may be employed. The electrodes 0 and C? are "mounted upon yielding springs E and E, and suitableadjust ing-screws, D and D are applied to the springs, whereby the pressure of the outer electrodes against the central electrode, 0, may be regulated. Normally they should be adjusted so as to touch the central electrode lightly when at rest.

The electrode 0 is electrically connected by a conductor, 1, with'oue pole of a suitable battery or other source of electricity. (Shown at O.) The electrode 0' is connected by a con doctor, 2, through the primary coil, 1?, of an inductioneoil. A conductor, 3, leading from this coil,is connected with the remaining pole of the battery. The electrode 0 is connected,

by a conductor, 4, through a resistance, 1%..

with the conductor 2. The secondary coil S of the inductorium has its respective terminals connected with the main line L L. The two coils are wound upon a core, I, of soft iron, applied to a diaphragm, J, and this device constitutes a receiver.

The operation of the apparatus is as follows: \Vhen the instrument is at rest, a cur rent from the battery traverses the conductor 1 to the electrode 0, thence through both the electrodes 0 and (7 and the conductors 2 and 4 to the primary coil of the indnctorium, and thence by way of the conductor 3 to the other pole of the battery. The core I thus receives amagnetization, dependent upon the current through the primary cell. Any variations in this current will cause corresponding variations in the magnetism of the core, and will also occasion induced currents in the secondary coil S, and such induced current-s will be transmitted upon the line L.

Variations in t he primary current are caused in the following man nor: \Vhen lhediaphragm Bis moved toward the electrode 0', for instance, the electrical contact of the electrodes 0 and 0' becomes more perfect, and a greater amount of current will flow through the coil 1?; The'diminulion'in the pressure between the electrodes C and G occurring at the same moment, or even the complete separation of these electrodes, will tend to cause but a slight reduction in the current, sincethe resistance R is sufficient to prevent nu'ich onrrentfrom flowing through the conductor 4. -*-Whcn the diaphragm is vibrated in the opposite direction, the resistance between the electrodes (1 and 0 becomes greater, and therefore the current is diminished. At the same time the pressure upon the electrodes 0 is increased, and the electrodes 0 and 0 may even be separated, and

- yet the circuitof the battery will remain comductors tends to lessen the magnetism of the core, and also acts upon the primary coil and tends to oppose the battery-current, so that electrical undulations of greater amplitude are occasioned than would be the case were the core a permanent magnet.

I claim as my invention 1. In a telephonic transmitter, an electrode,

two other electrodes applied to opposite sides of the same, means for increasing the pressure of the first-named electrode upon either one of, the other electrodes and at the same time diminish the pressure upon the other, branch circuits leading from the two outer electrodes, and an artificial resistance contained inone of the branch conductors.

2. In a telephonic transmitter, an electrode, two contact-electrodes applied to opposite sides of the same, means for increasing the pressure of the first-named electrode upon either of the other electrodes and at the same time diminishing the pressure upon the remaining electrode, branch circuits leading from the two contact electrodes, an artificial resistance contained in oneor" the branch conductors, and an inductorium having its primary coil included in the circuit with said branch conductors.

3. A telephonic transmitter, consisting of an electrode, two contact-electrodes applied thereto, means for causing the pressure of the first-named electrode upon the other two to vary inversely, two branch circuits leading from the respective contact electrodes, and an artificial resistance contained in one of the branch circuits.

4. The combination, wit-Ir. a movable diaphragm and an electrode carried or vibrated thereby, of two contact--electrodesmpplied thereto, the pressure against one electrode being increased as the pressure against the other is diminished, and vice versa, and an electric battery having one pole connected with the first-named electrode and the other pole with the two contact-electrodes, and an artificial rcsistanee interposed between one of the contactelcctrodes and said battery.

5. The combination, with a movable diaphragm and an electrode carried or vibrated thereby, of two contact-electrodes applied thereto, the pressure against one electrode be" \Vitnesses:

B. W. HAMLIN FRANK l). LMU'AM.

ICC

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