US1132613A - Telephone-transmitter. - Google Patents

Description

J. c. R. PALMER. TELEPHONE TRANSMITTER. APPLICATION YI'LED APR. 15, 1912 Patented 'Mar'. 23; 11915.

Fig. 2. I

Wbnesses;

MVenZc? UNITED STATES PATENT OFFICE.

JOEL C. B. PALMER, OF BROOKLYN, NEW YORK, ASSIGNOR TO WESTERN ELECTRIC COMPANY, OF NEW YORK, N. Y., A CORPORATION OF ILLINOIS.

TELEPHONE-TRANSMITTER.

Specification of Letters Patent.

Patented Mar. 23, 1915.

Application filed April 15, 1912. Serial No. 690,844.

To all whom it may concern:

Be it known that I, Jonn C. R. PALMER, citizen of the United States, residing at Brooklyn, in the county of Kings and State of New York, have invented a certain new and useful Improvement in Telephone- Transmitters, of which the following is a full, clear, concise, and exact description.

This invention relates to telephone transmitters, and has for its object to provide a transmitter structure in which the detrimental effect, due to an inactive mass of granular carbon or other comminuted material, is eliminated, and the transmitting qualities otherwise improved.

In the commonly known type of SOlldback transmitter employing comminuted material as a resistance-varying medium,

there has been a portion of the comminuted resistance-varying material which is practically inactive due to the fact that it has settled in the base of the button chamber and is very slightly agitated by the movement of the electrodes. This mass is, therefore, of relatively low resistance and forms a shunt to the path which is actually subject to variation. In accordance with this invention the detrimental feature of this shunt is obviated by so shaping the electrode chamber and adjusting the sizes of the electrodes that the percentage of the inactive material in the button is very small compared to the total amount, and is restricted to an area such that no portion of it is in contact with one of the electrodes, and any current which has a path through such inact a material must pass also through the material undergoing the maximum agitation. The structure preferably employed for accomplishing this result comprises a chamber, the wall of which is sloped or tapered to form the frustum of a cone and has located in the smaller end thereof an electrode of the same diameter as said smaller end. Located in the opposite side of said chamber is a second electrode having a larger area than the area of the first electrode exposed to the comminuted material in the chamber, the exposed area of the second electrode being so related to the chamber that the small amount of inactive material is restricted to a small area at the margin of said larger electrode, wlf 2h area is a greater distance from the smaller electrode than is any point on the exposed surface of the ele "'ode of larger area. The larger electrode may be formed of rigid material and secured to a flexible diaphragm of insulating material, or said electrode may be formed of flexible metal,

such as gold, of sufficient area to cover-the front of the chamber and have its inner surface near the margin thereof covered with insulating material to expose only a portion thereof to the comminuted material, the exposed area in both forms being practically the same. Any advantage in either of the structures, however, is probably in favor of the electrode of rigid material inasmuch as in the case of the electrode of rigid material the agitation is substantially uniform throughout the surface of said electrode, whereas in the use of the flexible electrode the maximum disturbance occurs in the central portion of the chamber and the amount of action decreases rapidly from the center outwardly toward the margin of the electrode.

Another feature of this invention relates to a structural detail whereby the minimum number of parts are used for constructing the button, and this feature consists in hollowing out the metal button supporting the electrodes to the shape of the chamber desired and applying a coating of suitable insulating material thereto, thus avoiding the use of a specially formed insulating member for the wall of the chamber, the result being to both cheapen and improve the structure.

In the drawings in which this invention is illustrated with electrodes of rigid material-Figure 1 is a sectional elevation of a transmitter embodying the invention; and Fig. 2 is a view of the transmitter parts of the invention separated and in position for assembly.

In Fig. 1 of the drawings, 5 designates the usual mouthpiece secured in a screwthreaded opening in a face plate 6. Secured to the rear of this face plate 6 is a metal bridge piece 7 provided with a centrally located aperture 8 through which is a clamping ring 12 adapted to press against of the smaller electrode 24 to the coma washer 13 of insulating material surminuted material beyond the margin of the rounding said block 9 and fitted into a relarger electrode 23 is greater than the discess 14 of the inner face of the bridge piece. tance from any point of said smaller elec- The chamber for the electrodes and comtrode 24 to the larger or movable electrode 70 minuted material is as follows: A metal cup 23. Thus it is evident that any current hav- 18 having a stem 19 thereon which extends ing a path through the comparatively inthrough an opening in the block 9 is proactive material beyond the margin of the vided with a sloping or tapering inner wall larger electrode must also pass through the 20 which is the shape of the frustum of a active material between the two electrodes, cone. The cup is provided with exterior thus undergoing the maximum change and screw-threads adapted to receive a metal avoiding the shunting of the active path. clamping ring 21 between which and the he feature of applying the insulating edge of the cup is clamped a mica diamaterial directly to the wall of the metal 15.' phragm 22 to which is secured a carbon elec chamber has advantages over prior forms of trode button 23. Located upon the opposite buttons in that it avoids the use of extra side of the cup is a second carbon electrode pl e parts ch s insulating strips which 24 secured to a metal disk 25 having a were necessary formerly when the chamber screw-threaded stem 26 engaging a screwwas formed In metal and the extra parts 20 threaded aperture in the stem 19 of the cup necessary for retaining the insulating strips 18. As shown, the electrode 24 is the same d mp ting the terminal connections to diameter as the smaller diameter of the cup the electrodes. wall 20, and is fitted into said cup wall so I 1mm that the exposed face of the said electrode A ph ne transmitter having an 25 i fl h ith th d f th cup 11 Th electrode chamber with a tapered we 1, an electrode 23 is larger in diameter than the electrode at one end of Said chamber, a electrode 24 but not so large as the largest d electrode rg than the first at the o diameter of the conical chamber. The wall Poslte end of Said h mber and having a iiiof th h b i t d as h w t 15 ameter less than the largest diameter of 80 with an insulating compound of any sui t- Sald chamberable form which is applied in a liquid state A telephone transmitter a ing an and subsequently hardened upon the wall. t ode chamber with a tapered wall, a S d t th i di k 23 i a t d 30 th stationary electrode located at the smaller outer end of which is provided with an insuend o id m r, a closure for the larger 35 l ti k b 31 i a t, ith a i end of said chamber, and an electrode car- 0 dentation 32 in a metal diaphragm 33 restried by said closure having an area larger ing against a strip 34 of insulation whi h than the area of said stationary electrode bears against the inner face of the face plate d maller than the total area of said earing against a collar 35 on the stud o r 40 30 is a damping spring 38 the outer end of 3. A telephone transmitter having an which is attached to the inner face of the electrode chamber with a tapered wall, combridge piece 7. The damping spring 38 is minuted material in said chamber,- a stainsulated from the bridge piece 7 but is in tionary electrode located at the smaller end electrical connection with a terminal block of said chamber a closure for the larger end 45 40 located upon the opposite face of said of said chamber, said closure presenting a bridg'e iece 7 but insulated therefrom The central conducting surface and a peripheral block 0 constitutes the terminal of the non-conducting surface to said commmuted transmitter with which the movable elecmaterial, said conducting surface having an trode 23 is connected. The terminal for area greater than the area of said stationary 0 the stationary electrode 24, if the transmitelectrode.

ter is to be used as an insulated transmitter, 4. A telephone transmitter havin an is connected with a binding screw 43 secured electrode chamber the shape of the frustum in the member 10 or if the instrument is to of a cone, an electrode of the same diamebe grounded, a ground Wire 44 will be led ter as the smaller end of said chamber se- 55 from the binding screw 43 along the bridge cured therein, and a movable electrode of piece 7 and attached at its opposite end to rigid material located upon the opposite a clamping screw 45. In this case, a bell side of said chamber, said movable electrode 48 inclosing the transmitter parts and being of greater diameter than the firstadapted for connection with a desk stand mentioned electrode and of less diameter 6 or other suitable subscriber set. will be than the largest diameter of said chamber. grounded. 5. A telephone transmitter having an By referring to the drawing it will be electrode chamber with a, tapered wall, noted that the relative sizes of the two eleccomminuted material in said chamber, an trodes 23 and 24 and the slope of the wall electrode at the smaller end of said cham- 6 20 is such that the distance from any point her, a second electrode located in the opposite end of said chamber, said second electrode having exposed to the comminuted material in the chamber an area greater than the area of said first-mentioned electrode but less than the area of the larger end of said chamber.

6. A telephone transmitter having an electrode chamber with a tapered side wall, comminuted material in said chamber, an electrode located at the smaller end of said chamber, a movable electrode of larger diameter at the'opposite end of said chamber, said larger diameter electrode having a conductive area exposed to said comminuted material of less diameter than the largest diameter of said electrode chamber.

7. A telephone transmitter having an electrode chamber with a tapered wall, comminuted material in said chamber, a sta- JOEL C. R. PALMER.

\Vitnesses:

G. M. CAMPBELL, W. F.- HOFFMAN.

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