US341519A - Instrument for transmitting vocal sounds - Google Patents

Description

(No Model.)

G. J. STUART.

INSTRUMENT FOR TRANSMITTING VOGAL SOUNDS.

No. 341,519. Patented May 11, 1886.

3m akin N. PETERS. Phemunia'gh nen Washington. 04 c.

UNITED STATES PATENT OFFI E.

CHARLES J. STUART, 0F LOIVELL, MASSACHUSETTS.

INSTRUMENT FOR TRANSMITTING VOCAL SOUNDS.

SPECIFICATION forming part of Letters Patent No. 341N519, dated May 11, 1886.

Application filed July 16, 1585.

My invention relates to transmitters for transmitting vocal sounds over awire or cord either operating electrically or mechanically; and it consists in certain additions to and improvements in the arrangement of transmitters. substantially ashereinafter described and claimed.

In tl1edrawings,Figure1 is asectional view of a portion of a telephonic transmitter provided with my improvements. Fig. 2 is an enlarged view of the improved mouthpiece detached, partly in section, showing the same. Fig. 3 is a front end view of the same.

A is the transmitter, of ordinary construction, containing the metallic diaphragm B, having a carbon contact-piece, 6, attached to its center. A spring, 8, is attached to the wooden casing of the transmitter, and has on its free end another carbon contact-piece, s, which is pressed by the spring against the contact-piece b, in the ordinary manner. L is the line-wire, which is connected on one side to the diaphragm B, and on the other to the spring 8. The transmitter has an aperture, 0, through the casing in front of the diaphragm, to permit speaking against the latter. All of these parts are well known and understood, and I do not intend to confine myinvention to any particular form of transmitter, as itis applicable to any one having the diaphragm B and the opening 0 opposite the diaphragm.

My invention consists in placing opposite to the diaphragm B, on the front side, against which the air-vibrations set in motion by the voice strike, a body of non-resonant substance in such a position as to compress such airvibrations between it and the diaphragm, and cause them to act more forcibly upon the latter, without creating conflicting air vibrations from such substance which will break up or destroy those created by the voice.

The non-resonant substance which I have found to give the best effects for the purpose Serial No. 171,753. (No model.)

described is air, and I confine a column or body of it opposite the diaphragm B of the transmitter, in such a manner as to prevent its escape at the instant that the air-waves of the voice enter the aperture 0, and pass between such column or body and the diaphragm, and thus confine the waves between such column or body and the diaphragm, and cause them to exert greater force upon the latter without creating supplemental or reflex waves, which would break up the vibrations of the diaphragm in response to the airwaves of the voice. By this. means I am enabled to increase the power of the transmitter to convey to the liuewire L the proper vibrations to reproduce speech at another station on the line, and at the same time I avoid all unpleasant ringing or breaks in the reproduced sounds.

In carrying out my invention I provide a supplemental mouthpiece, M, funnel-shaped, and having its smaller end snugly fitted into the circular aperture 0. IVit-hin the inner and smaller end of this mouth-piece I fix, by four small bars or struts, m m, the conical reservoir N, with its larger or open end to ward the diaphragm and a short distance from it, so as to leave spaces around its outer edge for the airwaves of the voice to pass between it and the mouth-piece M and impinge against the diaphragm B. \Vhen the air-reservoir N is made ofsufiicient internal depth to confine a column of air of a certain length within it, with the exposed end of the column toward diaphragm B, as shown, it will be found that no vibrations of the reservoir N will take place which will set in motion airwaves that will affect diaphragm B, and the transmitter will convey only the vibrations of the airwaves of the voice, greatly amplified by being forced into the space between the column of air cpnfined in reservoirN and the diaphragm.

I have shown the reservoir N of a conical shape, in order to allow the air-waves of the voice to pass by its exterior freely and enter the \aperture 0, around andbetween it and mouth-piece M; but it is not necessary that the reservoir should be made of this form to produce good results, as I have produced such resultswith it made in the form of a hollow cube and of a hollow pyramid and of ahollow hemisphere secured in the mouth-piece M, with the open sidein the same position as reservoir N, it only being essential in each case that the column of air in the direction of the axis of reservoir N, confined within either of these different forms of reservoir, shall be of a certain length and Within certain limits. Thelonger it is the more the power of the transmitter will be amplified'and the clearer it will transmit speech to another station on the line. Thusl have found a length of air-column of one-half inch confined in the reservoir N to increase the power of the transmitter one-half, and a length of three-fourths of an inch to nearly double its power, and a length of about one inch to nearly triple its power in long-distance telephony.

It will be observed that my improvement is portable, and can be applied to any transmitter at will.

Instead of a column of air, cork or some other non-resonant substance may be employed in substantially the same form and position as the body of air confined in reservoir N, and it will give good results; but I prefer to employ the confined air as described.

What I claim as new and of my invention 1S- 1. In a telephonic transmitter having aperture O and diaphragm B, a mass or column of non-resonant substance placed opposite the diaphragm and at a distance therefrom in the aperture 0, and in the path of the voice-waves entering the transmitter, and presenting a flat surface to said diaphragm, substantially as described. p

2. The combination, with the transmitter having the aperture 0 and diaphragm B, ofthe mouth-piece M and its air-reservoir N, formed with a sound passage or passages between said mouth-piece and said reservoir, and having the open and unobstructed end of the latter toward the diaphragm, substantially as described. v

3. In combination with the sound-receiver of the telephone-transmitter, the sound-deflector, preferably conical or conoidal in exterior form, located inside of the sound-receiver, with its apex presented toward the speaker, and arranged to form an annular space between its base and the walls of the sound-receiver, substantially as described.

CHAS. J. STUART.

\Vitnesses:

JOHN D. REED, GEORGE WV. POORE.

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