US1274035A - Differential microphone. - Google Patents

Description

(P. 1. HACKETT. I DIFFERENTIAL MICROPHONE. APPLICATION FILED bCT. 23. I916.

1,274,035. I Patented July-30,1918.

Inna/7 6 7 cured. A'cone deflector '7 is integral 1 the said mouth piece 6. v A series of per U ITED STATES PATENT oEEIoE.

PAUL J. AoKETnor sEATTLE, ASHINGTON, AssIerNoR TouNIvE nsAL HIGH POWER TELEPHONE COMPANY, or KING COUNTY, WASHINGTON.

DIFFERENTIAL MICROPHONE.

. Specification of Letters Patent.

Patented July 30, 1918.

Epplication filed October 23, 1916. Serial No. 127,109.

To all whom it may concern:

Be it known that I, PAUL J. HAGKETT, a citizen of the United States, and a resident of Seattle, in the county of King and State of ashington have invented certain new and useful Improvements in Differential Microphones, of which the following is ra full, true, and exact specification.

My invention relates to improvements in differential micropl'iones and has for its principal object to improve upon the construction of microphones and carbon cups as illustrated in my previous application, Serial No. 68,109, filed December 22nd, 1915, in that a carbon cup is provided which is non-packing, airtight and therefore does not deteriorate. Another object of my de- Vice'is to provide a simple and novel construction which embodies a metallic diaphragm having carbon cups adjustably secured oneon each side thereof. In microphones for high power work attempts have been made to use carbon diaphragms but the excessive breakage in thin carbon diaphragms of relatively large diameter. has

prevented their extensive use. The usual carbon cups give serious trouble from packing of the carbon granules, due to excessive heat, absorption of moisture and lack offacilities for expansion. -The above disadvantages have been overcome in my device. Other objects Will appear as my invention is more fully explained in the following specifications, illustrated in the accompanying drawing and pointed out in the appended claims. I a

In the drawings Figure 1 is a plan view of my device. Fig. 2 is a central cross section. of same. Fig. 3 is an enlarged cross sectional View ofone of my carbon cups.

Referring more particularly to the drawings, numeral 1 indicates a diaphragm housing which has an annularring 2 integral therewith. A metallic diaphragm 3 which is housed by a felt ring *1 rests within ring 2 and against housing 1. The diaphragn 3 may be held in place by any approved cl-z ping means. The upper portion of hodsing 1 is provided with a threaded mouth piece ring 5 within which the mouth piece is-seith housing 1 and is centrally located within orations 8 are cut in the housing between the cone deflector 7 and the mouth piece 6. A

cylindricalshell 9 extends downwardly-from housing 1 to a point close to diaphragm'3 and is of such diameter as to lie within the circle of holes 8 A bridge 10 is secured toring 2 and crosses 'the'draphragm diametri cally. A clamp block 11 is mounted uponbridge 10 and is insulated therefrom A pair of similar carboncups are mounted one on either side of diaphragm 3. One of the carbon cups fits within the cylindrical shell 9. Each of the cups is provided with a stem 12 one of which fits slida bly within a cored opening' 18 in deflector 7 while-the other passes slidably through bridge 10 and block- 11. Each carbon cup mcludes a main cup 1a which is integral with ste n 12 andwhich is threaded internally. A carbon disk 15 is held in the bottom of cup 14 byme Y s of a threaded nipple 16 which screws wit in cup 14. Nipple 16 extends beyond the open end of cup 14 and receives a threaded flange 17. A mica disk 18 'is'clamped between the nipple and the threaded flange 17 .11 copper plated carbon disk 19 is' secured against the inside of mica diaphragm 18 by means of a threaded rod 20 and a button 21. The outer ends of rods 20 screw into a common nut 22 which is .used to connect the cups and-to clamp the diaphragm 3 between the nut and one of the buttons 21. The space within the carbon cups adjacent the inner surface of nipple 16 and the mica disk 18. I fill with fiufiy asbestos which is held in place by small fragments and small threads being clamped between the ends of the nipple l6 and the carbon disk 15 and diaphragm 18. The remaining space within the cup is filled with granular carbon, The presence of the'.. flufl'y asbestos prevents packing of the carand scope of the invention, and I therefore desire to avoid being limited to the exact form shown and described. i

Having described my inv claim as nevviand dee're to t ters Patent, -is

1. The combination in a microphone which includes a dia )hragm ith a resilient lDSFr lating ring about its periphery and carbon cups (llSPOSBLl on opposite sides thereof, the movable electrodes of Which are fixed to said diaphragm, of means for holding said diaphragm and cups in an ope ative position said means including a face plate threaded to receive a mouth piece, said face plate supporting the said diaphragm at its periphery, a conical shaped piece recessed to receive one of said cups disposed at the center of said faceplate, there being apertures through said face plate disposed about the base of said conical shaped piece, said apertures communicating With the said mouth piece and being adjacent the diaphragm, and a bridge attached to the back of said race plate With an insulating lug thereon and bored out to receive another of said cups.

2. In a 'niicrophonc having a pair of similar cups containing granules of c-r;=n luctive mate 'ial, a movable diaphragm attached to said cups in common, the combination in each of said cups of an internally threaded main cup having a stem, a polished carbon disk Within the bottom of said internally threaded main cup, a threaded nipple within said main cup and extending beyond the end thereofla mica diaphragmadjacent the outer end of said nipple, said mica diaphragm supporting a movable electrode, said movable electrode including a carbon dish polished on its face and bored through the center to receive a stud Whose head is countersunk into the polished sln'ir'ace of the last mentioned disk, said, stud passing through the said mica diaphragm and screwing through a back plate forming a support for the last mentioned carbon disk, and the other surfaces of said carbon disk being electro-plated, a threaded flange screwed on the outer end of said nipple and against said mica diaphragm, and a finfiy asbestos packing ring Within said nipple and adjacent said mica diaphragm, whereby the grani'dar conductive material contained Within the cup is allowed to expand and packing is prevented. K

' PAUL J. HACKETT.

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