US242721A - Contact-telephone - Google Patents

Description

(No Model.) T. A. WATSON.

Contact Telephone[ No. 242,721. Patented June 7,1881.

E as Jud/a 71/ 1%0 7","

N4 mans Phummhn n her. Wnhiagtnn. 0.0)

iUNITED STATES PATENT OFFICE.

THOMAS A. WATSON, OF EVERETT, MASSACHUSETTS.

CONTACT-TELEPHONE.

SPECIFICATION forming part of Letters Patent No. 2e2,721, dated June '7, 1881.

Application filed April 7, 1831. (No model.)

T 0 all whom it may concern:

Be it known that I, THOMAS A. WA'rsoN, a citizen of the United States, of Everett, in the county of Middlesex and State of Massachusetts, have invented certain Improvements in Contact or Microphonic Telephones, of which the following is a specification.

My invention relates to that class of instruments known as microphonic or contact telephones, in which the impact of the soundwaves on the transmitting-diaphragms and the vibrations resulting therefrom so'act upon a variable resistance included in the circuits as to cause the said resistance alternately to increase and diminish. The continuous current of a galvanic battery flowing in the ciror less rigidly attached to the diaphragm, and

a second electrode normallymaintained in contact with the first by a certain initial pressure and suspended on asprin gor pendulum. Other forms of batterytelephones have been constructed in .which both electrode and phragm are rigidly supported.

when instruments of the firstmen'tioned class are used the spring or pendent electrode, not being entirely under control of the soundwaves, will introduce extraneous vibrations, which, not belonging to the sounds intended to be transmitted, consequently tend to confuse and render them indistinct.

It has also been ascertained by experience that battery-telephones of the second class which I have cited, by reason of the rigidity of the diaphragm and electrodes, have such a limited range of adjustment that in practice they cannot be used with a great degree of success for any protracted period of time. When such transmitters are, however, brought to their proper adjustment they give much bett-er results than those provided with a rigid diaphragm and spring or pendulous electrodes.

The objects, then,of myimprovement are to combine the good qualities of botlrforms of transmitter, and while maintaining a "wide range Qfadjustment to improve the strength and steadiness of the transmittedtones, and,

generally, to increase the efficiencyot' the apparatus.

To this end my invention consists, first, in the use of a diaphragm suspended upon springs at a distance from the front of its casing second, in the combination of a diaphragm or resonant plate suspended on springs having a conducting-electrode firmly attached thereto, and by the elasticity of the diaphragm-supporting springs normally maintained in contact with a second electrode mounted on a rigid support, and a mouth-piece or tubepassing through and supported by the front of the easing, and so arranged as to direct the entire force of the sound-waves on the center of the diaphragm.

In the accompanying drawings, Figure 1 is a sectional view of my improved contact-telephone. Fig. 2 is a sectional view on the line as a of Fig. 1, looking at the diaphragm; and Fig. 3 is a diagrammatic representation of a telephonic circuit, showing my apparatus used at one station as a transmitting and at the other as a receiving telephone.

In the figures, Ais the casing or box inclosin g the operating parts.

suitable material. This is pierced through the B is the front of said casing, and may be made of wood or any other It has been ascertained by experience that center for the reception of the mouth-piece O, i

which is firmly fixed therein. The end of the mouth-piece, passing completely through the block B a suitable distance, is brought into close proximity to, but not allowed to touch, the diaphragm D nearits center. The diaphragm D is supported by three steel springs, E E E, each of which is by one end riveted to it at equal distances one from the other, while the other end of each spring is brought round and fastened by a screw to the wooden blockor front supporting-board, B. The diaphragm is thus hung by the three springs at a distance from the front board, and a rubber ring is placed round its edge, as usual.

To the center of the diaphragm D is rigidly attached, by a screw through the plate, a carbon button, I), which forms a part of the electric circuit, and is pressed by the vibrations of the diaphragm with a varying degree of force against the opposing electrode or complementary contact-point c. This contact-point 0 also is a button or stud of carbon arranged in a setting of brass on the end of an adjustingscrew, d, which may by its milled head 0 be screwed up so as to impart to the contact of the electrodes b and c any required degree of initial pressure.

The wires to 'w of the circuit leading to and from the battery are attached one to the screw a of the diaphragm-spring E and the other to any part of the frame or case A which is in metallic connection with the adjusting-screw d or electrode 0. The whole casing, with the exception of the front covering, B, may, if desirable, be made of metal.

The position of the springs E E E with reference to each other is clearly shown in Fig. 2.

In Fig. 3, 1 represents a telephone-station at one end of a line, to, while 2 is a station at the other end. P is a battery included in the circuit, and the entire circuit terminates at both ends in the earth. This I have shown to illustrate the adaptability of my invention for use as areceiving-telephone in addition to its ordinary use as a transmitter. Its pencil-electrodebeing rigid, and the diaphragm D, owing to the elasticity of its supporting-sprin gs, being free'to. vibrate as a whole in a manner resemblin g the motions of the piston of a steamengine, repulsion between the contacts I) and 0 will be necessarily expended on the diaphragm, whereas in the ordinary forms of spring or pendulous electrode instruments it would be expended in moving the electrode, without materially affecting the diaphragm. Therefore my invention is eminently adapted for use as a contact-receiving telephone, on the principle enunciated by Emile Berliner in his patent of November 2, 1880, No. 233,969.

The method of arranging the mouth-piece O by bringing it near to the diaphragm in an open air-space instead of a close air-chamber is advantageous, as, while the sound-waves are concentrated on the center of the diaphragm, undue condensation of the air and the hollow sounds resulting therefrom are prevented.

My improved instrument is ordinarily to be used in connection with the well-known appurtenances of a local battery and induction-coil, which are employed in the practical application of this class of instruments; but these instrumentalities form no part of my invention,

and consequently are not herein shown, described, orclaimed. Neither do I claim herein a diaphragm or vibrating plate freely suspended by a spring, hinge, or pivot, as that I have made the subject-matter of a separate application.

Although in this embodimentof my invention I have described the diaphragm as being mounted on three springs of the conformation shown in the drawings, I do not confine myself to this precise shape or number, but may, without departingfrom the spirit of my invention, modify either shape or number, or both, or in place of the springs substitute any mechanical equivalent therefor.

Having now described my invention, what I claim is 1. In a contact-telephone, the combination of a diaphragm or vibratory plate suspended to produce, under the influence of sound-waves,

free rectilinear vibrations, and a rigid contactpoint, substantially as described.

2. In a contact-telephone, a diaphragm or vibrating surface which, instead of being rigidly clamped to the frame, is mounted on springs at a distance from the front piece or frame, and adapted by the elasticity of said springs to vibrate freely under theintluence of sound-waves, thereby varying its pressure on a rigid or immovable electrode or contact-point, substantially as described.

3. The combination, in a contact-telephone, of a spring-supported diaphragm carrying one contact-electrode of an electric circuit, and the rigidly-mounted opposite or complementary contact-electrode.

4. The combination, in a microphonic telephone, of a diaphragm supported on springs at a suitable distance from the frame of the instrument and carrying one electrode, a rigid or immovable opposite electrode, and a mouthpiece extending through the front of the casin g and adjusted in close proximity to the diaphragm, substantially as and for the purpos described.

5. The combination,with a spring-supported THOMAS A. WATSON. Witnesses:

Tnos. D. LocKWoon, W. G. ToMPKINs.

Images