US308956A

US308956A - Telephone-transmitter

Info

Publication number: US308956A
Authority: US
Publication date: 1884-12-09
Anticipated expiration: 1901-12-09

Description

(No Model.)

W. H. EOKERT.

TELEPHONE TRANSMITTER.

Patented Dec. 9, 1884.

oo'ooo INVENTOR William fl.Ec/ cert,

UNITED Sterne PATENT triers.

\VILLIAM H. EOKERT, OF NEW YORK, N. ASSIGNOR TO THE AMERICAN BELL TELEPHONE COMPANY, OF BOSTON, MASSACHUSETTS.

TELEPHONBTRANSMITTER.

SPECIFICATION forming part of Letters Patent N0. 308,956, dated December 9,1884.

Application filed December 2-1, 1883.

T0 (tZZ whom it may concern.-

Be it known that I, WILLIAM H. Eonnn'r, of the city, county, and State of New York, a

citizen of the United States of America, have invented a new and useful Improvement in TelephonicTransmitters, 01" which the following is a specification.

Iam aware that others have employed for a tension-regulator, or means for varying the resistance in a telephonic transmitter, finely-divided conducting material, such as finelycrushed carbon, coke, metallized carbon-powder, and powdered metal in a loose and free state within a chamber located in close proximity to the vibrating diaphragm of the mouthpiece; but in all such cases the operation of the instrument is uncertain, owing to an ab sence of capacity for maintaining adjustment between contactsurfaces.

Myinvention has for its object the obtaining of a vibratory contact between surfaces of large area which are covered or impregnated with particles of conducting material,whereby wide variations of electrical resistance may be effected under theinfluenceofsound-vibration,While at the same time permanency and certainty of adjustment is attained, which is impossible where powdered particles in a free state of movement are used. To this end I employ two sheets of metallic foil, forming both electrode-plates and a diaphragm, suspended side by side in contact with each other and below themouthpieceof the transmitter. The electrode-plates are so bent as to form a flat surface beneath the mouth-piece of the transmitter, or so as to form a \l-shaped opening between them. The electrode-plates, being so bent, are attached by those parts which are at right angles to the contact-surfaces to the support or base-board of the mouth-piece, and the only diaphragm employed are those parts of the electr0de-plates opposite the orifice of the mouth-piece. The contact-surfaces of the foil plates are coated with an adhesive gummy substance which is impregnated with fragments or particles of a conducting material which, when dried, forms a hard and elastic body. The material which I prefer to use for this purpose is a composition or liquid composed ofgelatine and glycerine, gelatine bc- (No model.)

ing dissolved in water in the pro-portion of about one to five, in weight, and to this glyccriue is added to an amount of about oneeighth the weight of the gelatine. Before ap plying the paste to the contact-surfaces of the electrode-plates a powder reduced from any good conducting material is mixed with the paste only in sufficient quantity to .render the whole composition a conductor of high resistance. After being applied to the 'electrodeplates, and after nearly all of the moisture has been evaporated therefrom, the plates may be subjected to a sufficient pressure to form the coating into a durable body.

Figure 1 isasection view of the transmitter. 6 5 Fig. 2 is a section view of a modified form of the electrodes. Fig. 3 is a face View of a perforated electrode.

Referring to the drawings, F and D are foil plates coated on their sides which are designed to face each other with a metallized paste, as above described 5 and thus prepared they are suspended, with their metallized surfaces facing each other and in contact with moderate pressure, beneath the orifice of the ,7 5 mouthpiece B of the transmitter.

O and E are binding-posts mounted upon a case or box, A, of the transmitter, and said binding-posts are electrically connected to the metallized contact-plates D and F. Plates D s and F are shown in detail in Figs. 2 and 3. The electrical circuit from the battery of the transmitter is thus completed from bindingpost 0 to contact-plate D, contact-plate F, binding-post E, and thence through the electrical circuit and battery back to binding-post O. The contact-plates, one or both, may be made from foil, paper, or thin sheet metal; and one only or both of said plates may be coated with the metallized paste, as herein- 0 before described.

I find that iron scalings, filings, drillings, or any finely-reduced metal of good conducting quality is well adapted for my metallized coat- Instead of making the foil-plates into perfeet sheets, they may be perforated, leaving only a web for a body, as shown in Fig. 3. A blank sheet may be provided with interstices and then coated, leaving the interstices filled ioo with metalliz ed material; or the plates may be coated with metallized material without filling the interstices, thus forming perforated plateelectrodes, which may in that form be attached to and used in a telephonic transmitter.

Vibrations of the atmosphere set up in the opening B are imparted to those parts of the electrode-plates which are exposed to the orifice, and cause an increase and decrease of pressure between the contiguous surfaces of F and D, and a consequent change of electrical resistance in the telephonic circuit, thereby enabling the reproduction of articulate speech through the medium of a telephonic receiver placed at any point in the electrical circuit.

I am aware that a teleph'one-transmitter consisting of two broad elastic electrode-plates inclined toward each other and in contact at their convex ends, and constituting the electrodes, is not new; but my invention differs from such form, in that the two plates have broad surfaces of definite magnitude, which are in contact with each other throughout said surfaces, but under varying pressure, whilein the transmitter referred to the contact is merely tangential.

I am also aware that'a comparatively rigid support for one electrode, in connection with a broad flexible electrode which makes variable surface contact with the first, has been used in transmitters.

I am also aware that an electrode consisting Y of a body of carbon composition which is subnation of two light elastic plates having broad contiguous surfaces, forming the electrodes, said surfaces being coated with an inferior conductor, for the purpose specified.

2. In a contacttransmitter, the electrodes having broad surfaces normally in contact, formed of a metallized paste, substantially as specified.

3. A light flexible electrode, substantially as described, for a contact-transmitter havnation of two electrodes consisting of broad elastic plateswith definite extended surfaces in contact with a mouthpiece arranged to concentrate the sound-waves upon the non-con tacting portions of the electrodes, and to vary the pressure between them.

5. In atelephone-transmitter, the combination of two electrodes consisting of broad elastic plates having definite invariable extended surfaces in contact with each other.

6. In a telephone-transmitter, the combination of an electrode consisting of a broad elastic plate having a definite invariable ex tended surface adapted to make a variable electrical contact with a second electrode of broad surface of im perfect conducting material.

V. H. EOKERT.

Witnesses:

W. B. VANSIZE, WM. ARNOUX.