US844635A - Carbon-ball transmitter. - Google Patents

Description

No. 844,635. PATENTED FEB. 19, 1907. K. M. TURNER & N. W. JOHNSTON.

CARBON BALL TRANSMITTER Jam; o JAH #ilk-74W# TE STATES PATET OFFIOE.

KELLEY M. TURNER, OF NEW YORK, AND NORTON W. JOHNSTON, OF CHAP- PAQUA, NEW YORK, ASSIGNORS, BY MESNE ASSIGNMENTS, TO GEN- ERAL ACOUSTIC COMPANY, A CORPORATION OF NEW YORK.

CARBON-BALL TRANSNHTTE.

Specification of Letters Patent.

Patented Feb. 19` 1907.

Original application filed September l8, 1905, Serial No. 277,61 6. Divided and this application filed September 8, 1905- Serial No. 277,615.

To 11,27/ whom, it may concern.: Be it known that we, KELLEY M. TURNER and NORTON W. JOHNSTON, citizens of the United States, residing, respectively, at the city of New York, county of New Ork, and State of New York, and at Chappaqua, county of Westchester, and State of New York, have invented certain new and useful Improvements in Carbon-Ball Transmitters, io of which the following is a full, clear, and exact description.

Our invention relates to carbon-ball transmitters. In our companion application, Serial No. i5 277,616, filed herewith, we have particularly described the features of a transmitter which is adapted to contain carbon balls as the operative element. In the present divisional case. we desire to particularly describe and zo claim the construction and arrangement of the carbon-ball element per se.

Carbon balls have hitherto been used in telephone-transmitters; but so far as we are aware their use has been entirely abandoned in all modern practical telephone-work. The reason for this abandonment was on account of the inertia of the carbon masses, which were constrained to take higher rates of vibration than it was possible for them to at- 3o tain under the influence of a transmitter-diaphragm. W hen balls of any ordinary size, such as have always been employed, were used, the vibrations of the diaphragm caused the balls to be knocked back and forth en- 3 5 tirely out of rhythm with the diaphragm, so

that the electrical pulsations instead of corresponding with the sound are largely the result of the impact of the heavy balls against the diaphragm in their independent move- 4o ment. In other Words, as the diaphragm vibrates the heavy balls acquire suoli an inertia that they wholly break contact therewith and in returning to position strike the diaphragmsurface with such a hard blow as to produce too great a contact and obviously one having no relation to the sound transmitted. This defect is known as cracking or frying and is quite intolerable in practice. In order to overcome the defect, suoli balls have 5o been abandoned and pulverized oi granulated carbon substituted therefor, which is free from the above defect, although it is not pack hard and is not very sensitive. The

production of an exceedingly sensitive transniitter is a great desideratum in the tolephone art,-particularly for long-distance work. Such a transmitter would also be advantageous in local work, since it would 'avoid the necessity of placing the lips closely 6o thereto, which is obnoxious from a sanitary standpoint. By the present invention we provide such a transmitter.

Our invention consists in the construction, combination, location, and arrangement of parts, all as will be more fully hereinafter set forth, as shown in the accompanying drawings, and finally particularly pointed out in the appended claims.

The drawing shows a 0'ready-enlarged sec- 7o tional view of a carbonall transmitter embodying the principles of our invention.

Broadly stated, our invention consists in making and using carbon balls of exceedinglyreduced'diameter, amounting to three 75 or four times as small in diameter and from twenty-seven to eighty-one times as small in mass as those heretofore used. The effect of such a marked reduction in the size of the balls is manifold and leads to the most sur- 8o prisine' results in practice. By virtue of the exceedingly-reduced inertia each ball can attain a proportionately higher rate of vibration and in practice a vbration which accords with any ordinary tone of speech used in telephone transmission. Also by virtue of the reduced inertia there is no hammer effect of the balls against the diaphravm when returning thereagainst to produce the objectionable frying and cracking el'l'ect hereto- 9o fore always incident to the use of balls. By virtue of the reduced size the number of points of contact is increased as the cube of the diameter, with a proportionate increase in sensitiveness and e'l'liciency. At. the same 95 time there is retained all thc advantawes which are obviously attendant to looseymounted balls-namely, extreme mobility and uniform contact through out the mass which the balls make on account of their roo symmetrical contour.

Referring to the drawing, which is drawn to a greatly-enlarged scale in ordcr that the sha ie of the individual balls may be possible of illustration in somewhat near the proper an advantageous material, since it is apt to 1 relative size thereof, 1 designates a carbon block having recesses 2 in the face thereof, which we preferably form of hemispherical section, and polished interiorly in order to obtain more efficient contact and to enable greater mobility of the balls. A convenient arrangement is to make the block 1 circular and to. arrange the recesses 2 annularly around the face with an additional cavity3 at the center.

4 indicates a base-plate into which the block l is inset as described in our, companion applicationF above referred to.

5 designates the carbon diaphragm, which is supported in exceedingly intimate roximity to, but not actually touching, the lock 1, as also set forth in the above case.. The arrangement is such that the diaphragm 5 does not vibrate sufficiently vto quite touch thee block 1 under any ordinary vibrations incident to its use in telephone-work.

Within the recesses 2 We place the carbon balls 6, so as to substantially two-thirds fill each cavity formed between such recesses and the diaphragm 5. `The size of these balls approximate the characteristics of very fine sand, they being, in fact, from twotenths to five-tenths of'a millimeter in diameter.

among themselves with every vibration oi the dia hragm. They do not pack together in use, ut retain their mobility and secure a multitude of contact-points, and have masses whose inertia is so small as to accommodate any periodicity of diaphragm vibration.

Wcv do not, of course, desire to be restricted to the exact size of the balls which These balls lie loosely in their containing-recesses and -move about freelyl aliases we employ, it being merely essential to use a size whose inertia is at least ten or twenty times as small as the forms heretofore used, it being evident that every size of ball has its own periodicity'ol vibration, and it is merely necessary to go beyond the limits of vibration of ordinary speech. The transmitter will work eiciently and avoid frying, cracking, and snapping for any size smaller than the above limit.

What we claim is- 1. In a telephonie transmitter, a block having cavities, a carbon diaphragm in intimate juxtaposition thereto, and carbon balls contained between said dia hragin' and said block and loosely collected 1n said cavities, said balls having a maximum diameter of iive-tenths of a millimeter, whereby their natural period of vibration is greater than the period of vibration of ordinary human speech.

2. In a telephonie transmitter, a block having a series of hemispherical cavities polished on their interior faces, each cavity being substantially two-thirds filled with carbon balls loosely resting against the diaphragm, each carbon ball being of a diam- ',eter of from substantially two-tenths to fivetenths of a millimeter, whereby the balls may take a periodicity of vibration which accords with that of the diaphragm.

In witness whereof we subscribe oursignatures'in the resence of two Witnesses. ELLEY M. TURNER.

NORTON W. JOHNSTON.

Witnesses:

ALFRED W..PRocroR, FRANK S. OBER.

Images