US357452A - Telephone-transmitter - Google Patents

Description

(No Model.)

P. BLAKE.

TELEPHONE TRANSMITTER. No. 357,452. Patented Feb. 8, 1887.-

N. PETERS. Plmwuxho n her. Washington D. C.

UNITED STATES PATENT @FFiCEO FRANCIS BLAKE, OF VVES'ION, ASSIGNCR TO THE AMERICAN BELL TELE- PHONE COMPANY, OF BOSTON, MASSACHUSETTS.

TELEPHONE-TRANSMITTER.

SPECIFICATION forming part of Letters Patent No. 357,452, dated February 8 1887.

(No model.)

To all whmn it may concern-.-

Be it known that I, FRANCIS BLAKE, of Weston, in the county of Middlesex and State of Massachusetts, have invented certain Iniprovements in Telephone-Transmitters, of which the following is a specification.

My invention relates tothat class of battery-telephones which are popularlyknown as transmitters, and refers, especially, to the species wherein the resistance of a mass of granulatedconducting material inclosed in a chamber between two conducting-electrodes is varied by the vibrations of a horizontallymounted diaphragm or vibrating plate c011- stituting or supporting one of the said electrodes, the whole being included in the circuit of a voltaic battery. These variations develop the necessary and corresponding changes in the current of the said battery, and, passing to any suitable telephonereceiver conductively or inductively, included also in the same circuit, effect therein a reproduction of the sound which originally actuated the transmitting-diaphragm. In the practical operation of these transmittersit has been found very convenient to construct them in a compact and portable form which may be readily mounted upon a suitable support. It is also advantageous to so construct these instruments that the several elements or parts thereof may be interchangeable, whereby when any one is out of order it can be replaced with facility by another, dispensing with the necessity of changing the complete outfit, or even'of removing the ordinary adjustable supporting-arm.

In accordance with these views, the object of my invention is to meet the above requirements and to consolidate the operative parts of the transmitter into a simple combination of few elements readily attachable and detachable, perfectly interchangeable, and of such simplicity as to require no special degree of expertness in its care or management,while it shall at the same time be easy and economical in construction and repairs. These objects I achieve by the construction which I shall hereinafter describe; and to this end my invention consists, especially, in the peculiar shape of the different parts of the transmitter, and in a part of this invention, Figure 1 is avertical cross-section of a transmitter showingmy invention. Fig. 2 is a plan view of the inclosing-cap thereof. Figs. 3, 4, 5, and 6 are plan and cross-section views of details. Fig. 7 is a plan view of one form of pendulous or back electrode; and Fig. 8 is a crosssection (for purposes of comparison) of the construction employed tosome extent prior to my invention.

I will. first describe the latter construction.

In the construction shown in Fig. 8, which, as stated, has heretofore been experimentally adopted, the operative parts comprise the external metallic case, A, having an upward eX- tending circular flange, d, threaded internally near its edge, and having a central aperture in its base, which aperture expands into a speaking-tube or mouth-piece, B, the walls of which may be cast or otherwise madeintegral with the body of the case, as in Fig. 8, or which may be separately made and mechanically attached thereto, as in Fig. 1. An annular metal plate, 9, faced on its under side with insulating material a, and having also a central opening or aperture, is placed within the case and lies upon theinner surface of the base thereof, but is not in electrical connecform a seat for the flange of the pendent electrode E, which projects downwardly into the ring, and when complete and ready for operation into the granulated material. An annular plate, 7:, closed at its lower side, with the exception of a central erforation, hasa shoulder cuton theinnersurface oftheportion surrounding the said perforation, upon which shoulder the diaphragm is supported, and which aids in forming below the diaphragm an air-space or vocalizing chamber. This plate has a flanged edge threaded with a female screw, and after the disk of platinum foil constituting the vibrating diaphragm is placed upon the flat shoulder cut therein the non-conducting ring F is screwed down thereon, clamping the edge thereof. The pendent electrode is then seated in the countersink, the granulated material filled in, and the inelosing cap or cover D, which has its flange threaded oirboth outside and inside surfaces, is screwed down upon the insulatingring, as shown, to hold the electrode in place, the inner thread being adapted to engage with the screw on the outside of the insulating-ring,- while the outer thread is adapted to engage with a female screw cut on the inner surface of the flange d of the metal frame or external case A. The whole, by means of the external thread on the outer side of the cap-flange, may then be attached to the standard transmitter frame or holder, the pendent electrode being connected with the circuit through the cap, case,and supportingarm. This construction hasbecn found unsatisfactory in some respects, it is comparatively costly and intricate, requires considerable skill and a high class of workmanship in manufacture, while the number and necessary fineness of the screw-threads is disadvantageous, and even with the greatest care it is a fact that the threads frequently strip, especially that one which is cut on the outside of the insulatingring. Moreover, it is most essential that the fragile platinum diaphragm shall be kept free from wrinkling, and it has been found that the action of screwing the parts together is apt to wrinkle and otherwise damage the same. The construction I have devised is, on the contrary, severely simple, very cheap, and is held together solely by machine-screws.

I adopt the same general form of outer case, A, and mouth-piece B. The inclosing-case is bored out true, and has a horizontal flange, F, atthe edge of the cavity. A bed-plate, G, (shown in detail in Figs. 3 and 4,) is provided, consisting of a circular perforated metal baseplate, 71, with a shoulder, g, and an upwardlyprojecting flange, t, at its outer edge. A binding-screw, 7:, forming one of the transmitterterniinals, is attached to the plate, and a nonconducting partition, 2, is aiiixed to the lower face of the said plate for the purpose of insulating it from the inclosing-case. The platinum-foil diaphragm i is placed in this bedplate and seated upon the shoulder g, the v0- calizing-chambcr being thus formed between lapping the same.

the said diaphragm and the lower part, h, of the base-plate, the circular perforation of the said plate being the inner termination of the mouthpiece or speaking-tube. I provide next a non-conducting ring, f, formed as shown in Figs. 5 and 6, having a shoulder, in, turned to fit snugly in the flange t of the plate G, and being also countersunk atl to form a seat for the pendent electrode E. The lower edge of this ring is inserted in .the cavity of the plate G and clamps the edge of the diaphragm without subjecting the same to the twisting or distorting motion inseparable from a serewcoir nection. The elect-rode E, of any customary or suitable construction, may then be inserted, its edge lying in the seat Z, provided therefor. The variable resistance material being new filled in a manner well understood, the entire appliance, as a whole, may be placed in the inclosing case, the binding screw passing through the hole at one side of the lloor there of, but being insulated therefrom by partition 2. I finally provide a cap-piece, J, fitted'to the external ease, and having a flange, m, over- This cap makes contact with the electrode E and connects the same electrically with the metal case and supporting-arm, and through the said arm with the electric circuit. It is secured to the flat flange F of the case by any desired number of machine-screwsj. I have shown three as being both convenientand symmetrical. Small bolts and nuts may of, course bealternately used,

The outer peripheral boundary of the insulating-ringf, which forms the non-conducting wall of the inner chamber, is turned to fit exactly the bore of the external case, and it will be seen that by this construction a compact instrument is very economically furnished, which possesses the several advantages I have hereinbefore described.

I do not desire to claim herein any feature relative to the form, character, or position of the electrodes, or the combination of the electrodes with the resistance-varying medium, as I am aware that these features are not new. The essence of my invention lies in the construction of a skeleton transmitter, the several parts of which are extremely simple, accessible, economical, and easily taken apart and put together, the whole being held in place, when put together, by a small number of machine screws or bolts and nuts.

I claiml. The combination, substantially as hereinbefore described, in a telephone-transmitter, of the flanged external case and mouth-piece attached thereto, the diaphragm-seat mounted therein, but insulated therefrom, the non-conducting ring fitted to the innersurface of the inclosing-case, surmounting the said diaphragmseat and adapted to clamp the diaphragm, and the cap-piece attachable to the external case and adapted to hold the several elements to gether by means of machine-screws, as specified.

2. In a telephone-transmitter of the class herein specified, the metal external case, the insulated diaphragm-seat with circuit-terminal attached thereto, the vibrating diaphragm, the non-conducting clamping-ring adapted to fit within the inclosing-case, and also to the insulated diaphragm-seat, the pendent or fixed electrode mounted upon the upper edge of the said non-conducting ring, and the surmounting cap in contact with the said electrode and attached to the metal inclosing-case by machine-screws or their equivalents, whereby the parts are securely held in place, and whereby the fixed electrode is electrically included through the inclosing-case and support in the voltaic circuit, substantially as described.

3. The combination, in a telephone-transmitter, of the shouldered diaphragmseat, the diaphragm mounted therein, and the non-c0nducting ring accurately fitting the upwardlyprojecting flange of said diaphragm-seat and adapted to clamp the edge of said diaphragm and to hold the same in place, and to serve also as the non-conducting side wall of the 0perating-chamber, as specified herein.

4. In a telephone-transmitter of the class hereinbefore described, the flanged external case, A, and mouth-piece B, combined with the surmounting cap-piece J, attached to the flange of the said case by the machine-screws j, or their equivalent, as herein specified.

5. The herein-described skeleton transmitter, comprising the external flanged metal case with mouth-piece attached to the base thereof, the diaphragm-seat adapted to be in the floor of the metal case, but insulated therefrom, the non-conducting ring or gland fitted inthe' external case and adapted to clamp the dia-

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