US1330391A - Telephone-transmitter - Google Patents

Description

Patented Feb. 10; 1920.

,Vw p w r 0M 4 Fill A. P. PINKLER. TELEPHONE TRANSMITTER. APPLICATION FILED MAR. 2, 1911. 1,330,391.

z y rmw .UNITED STATES PATENT orrroE.

ARTHUR P. PINKLER, OF RIDGEFIELD, NEW JERSEY, ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

TELEPHONE-TRANSMITTER.

Specification of Illetters Patent. Patented Feb, 10, 1920. I

Application filed March 2, 1917; Serial No. 151,998.

To all whom it may concern:

Be it known that I, ARTHUR P. PINKLER, a citizen of the United States, residingat Ridgefield, in the county of Bergen and State of New Jersey, have invented certain new and useful Improvements in Telephone-Transmitters, of which the following is a full, clear,concise, and exact description.

This invention relates to telephone transmitters, and in particular it relates to an improved type of microphonic element or transmitter button wherein comminuted material, such as granular carbon, is used as the medium of variable resistance,

Its object is .the construction of the current in the granular material to a path so located with respect to the fixed and movable electrodes of the button that the current therein will be subjected to a maximum variation, under the influence of electrode motion, without the use of small electrode surfaces and the burning difficulties inherent in such use.

To this end, the invention, as applied to the usual cylindrical type of transmitter button, provides, on the wall of the carbon chamber, an inwardly projecting flange or rib, which, being insulated from the granular material, constricts the central current path in the button to an opening or channel whose cross-sectional area is less than the area of either the front or rear electrodes. The invention, therefore, while presenting in general the advantages of construction and high transmittin efliciency of the transmitter of Palmer atent No. 1,132,613, presents an improvement over that construction in that to obtain the required concentration of the current, it is no-longer necessary to employ a small electrode surface for the rear or stationary elect de. 4

T e invention will be more clearly understood by reference to the accompanylng drawings, inwh-ich Figure 1 shows t e transmitter of this invention in partia cross-section; and Fig. 2 shows in extended form the general construction of'the transmitter button or microphone element.

Referring to the drawing, 3 is a transmitter casing having a front plate 4 threaded to receive the usual transmitter mouthpiece 5. The front plate 4 also carries the bridge member 6 in which the microphone element or transmitter button 7 is adjustably supported. A damping spring 8 is also carried by the bridge 6, and serves to hold the movable electrode member 9 and the diaphragm 10 against the front plate 4. The dampin spring and diaphragm construction wilfibe more clearly understood by reference to Scribner Patent No. 1,050,304.

Referrin in detail to the construction of the microp one element or transmitter button which is the subject of this invention, 11 is a cup-shaped member having a shank '12 for attachment to the bridge 6 in the usual'manner. .The member 11 carries the rear or stationary electrode 13 of the transmitter, and is threaded to receive a'collar or annular member 14. This member 14 may be of insulating material, or it may be of metal with the inner surface coated with an insulating japan or other insulating coating. It has an inner annular projection or flange 15, preferably of V -shaped crosssection. The front electrode member 9 carries the usual flexible annulus 16 of mica or other suitable material, and forms the front closure for the button chamber, being held to the member 14 by the usual threaded ring 17. In the construction as shown the flange 15 is seen to project into the granular mass beyond theperipheries of both the front and rear electrodes. This has the effect of increasing the current path between the peripheries of the electrodes, and there fore serves to eliminate the path of low resistance and consequent high. current density which obtained in the transmitter of White Patent No. 485,311. This low resistance path at the baseof the carbon chamber has been found to have a rather'serious shunting effect on the active current path in the button, and to introduce a transmission loss. The present invention, while retaining all of the benefits derived from the large electrode surfaces of the White transmitter, restricts the current in the transmitter button to the central part of the granu: lar mass, thereby eliminating the shunting effect of the low resistance path through the button and'connning the current flow to that part of the granular mass which is subjected to the maximum agitationdue to sound waves impinging on the diaphragm 10.

What is claimed is:

. 1. In a, telephone transmitter, an elec-- trode chamber, two electrodes spaced apart v Within said chamber, comminuted material I trally restricted.

v 2. In a telephone transmitter, an electrode chamber, two electrodes spaced apart in said chamber, comminuted material be- 10 tween said electrodes, and an annular projection of V-shaped cross-section on the Wall of said chamber, and intermediate said electrodes for restricting the current flow therebetween to a path Whose central crosssectional area is less than the area of either 15 of said electrodes.

In Witness whereof, I hereunto subscribe my'name this 1st day of March A. D., 1917.

ARTHUR P. PINKLER.

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