USRE13035E - Telephone-transmitter - Google Patents

Description

- w, W. DEAN; TELEPHONE TRANSMITTER. nruoumn his Inn, 1909'.

'Reisued Now-2,1909.

ZSKEETS-SHEET 1.

2220f? jOR Jar veloped in man} commereiall UNITED STATES: irin rnntr orr on. j

WILLIAM W.DEAN, or ELYRIA,

onto, ASSIGNOR TO 'rr'nn DEAN ELECTRIC COMPANY, A conroaa'rron or cure; I

TELEPHONE-TRANSMITTER.

Specification of Reissued Letters Patent. Reissued NOV. 2,1909- Oflginal No; 823,768, dated June 19, 1908, Serial no. 224,299. Application for reissue. filed May 17,1909.

semi No. 496,680.

To all whom it may concern:

Be it known that I, WILLIAM W. DEAN, a citizen of the United States, residing at Elyria, in the'count'yof Lorain and State of Ohio, have invented certain new and useful Improvements in Telephone-Transmitters, of which the following is a specification, reierence being had therein to the accompanying drawings.

My invention relates to telephone-transmitters, and more particularly 'to microphones in which granular or fin'ely-divided material, such as powdered carbon, is-used as the resistancewarying medium. It has for its object theproduction of an instrument'of this class in which the'parts shall be easy to assemble and adjust, with cient when assembled and adjusted.

The highest type of granular transmitter known in the art to-day is that having a separate resistance-chamber. or button containing the electrodes and the granular material supported in roximity to the diaphragm which is usua ly directly connected to one of the electrodes, while the other is ri idly fixed, bein o ."the instrument fiy means of a bridge or its equivalent. This type .has' been deforms and is widely used 11 spite of this it is subject to certainrawbacks and defects inherent in the general design which prevent the attainment of'full eflicienc I have discovered some of these de ects and in the design presented herewith have removed them, with the result that my im IOVQd transmitter is not only of ver high e ciency in individual instances, as we 1 as eas. to assemble and adjust, but its highlflei ciency and the adjustments are'uniform all instruments of the type. v

, One defect inherent inlthe transmitters heretofore. used is the attachment of the diaphragm to the frontelectrodethrough a cent-raland very small-portion of its superficial'area. While the' greatest am litude of vibrationltlieoretically,exists at t is point, there is never asuflicient area of connection elcctr e back ther diaphragniot nib attached to the frame stantially the area of the electrode. Another defect is in the positive connections of both electrodes. In caseiof a very small var'iationgin drilling or assembling or ,in the punch that produces the central-opening in the diaphragm the arts will not aline perfectly, and as the separately, with itstwo stems presumably perfectly alined, there is a final slight distortion of the auxiliary diaphragm which creates a normal compression strain on one side of the chamber and the vdia hragm and a tension strain on the other. he result is a drop in the individual instrument and lack of-uniformity in the type. Another defect is the fixed character of the vordinary.

containing-cup, which permits the-granules therein to pack-- or .to be packed. It a well-knownia'ct tha't in the best solidback transmitters a the carbon may be pro uced-byplacingthe lips to the mouth-piece and exhausting the air from in front of the dia hragm. 'The latter bucklesforward, the car on drops into. a mass, and When the diaphragm through its own resilience goes backlnto normal position the carbon is compressedinto' almost solidity. It is impossible topurposely pack my instrument and practically impossible to pack it through continued use, asI cause the containin '-cup' to move with the diaphragm, but 0 not fasten it thereto. i Any orced movement of the diaphragm leaves the cup behind, therefore, while ordinary packin is prevented by the constant agitation 0 the mass of rariules. Another defeet is in the lack ot proper tensionof the diaphragm. In a free diaphragm supported outside skin, its resilience depending upon this phenomenonf In the dead space there is no-resilience. Thediaphragm is dead andthe' traveltlirough that space, twice for each vibration, is equivalentto'lpst motion, so'-far-- a's'aictivity is concerned; This is partly overcome 'bythe'welhknewn damper springs;

utton is assembled acked. condition ofbut these are not symmetrically placed, and

their use is entirely. without any ,understanding of the principle I have discovered. I remedy this defect by puttin the center of the diaphragm under a strain symmetrical: at all tunes and useful ma secondary function, of maintaining contact between the electrode-cup and the'diaphragm. Other defects might be" pointed out; but these are many of the apparent, and the method of overcoming them will also be apparent from .cannot get outof'alineme'nt. Hence adj 11stments'are uniform.- Slight inequalities-in the thickness of diaphragms are also taken up by the springs in adjusting, and the instrument is ca able'of a very fine adjustment, with big efliciency and great consequent sensitiveness.

My, invention isillustrated in the accmnpanying. drawings, in which I ,F1-gu'1e l-lsa sectional view 'of a' granular transmitter embodying; my imprm'ements.

Fig. 2 is a similar "iew of a. modified form thereof, showing a preferred arrangement of the contact-springsmnd connections; and

3 "Fig. 3 is a detail view of thebridge and springs shown in Fig. 9..

In Fig. 1, A is a circular front plate. usually a casting, centrally apertured and screw-threaded to receive the mouthpiece A. This is preferably of hard rubber and is providedwvith the perforated septum 0, adapted to protect the diaphragm of the instrument. The plate A upon its rear side is provided withan annular face a to receive the diaphragm D, and in front of the diaphragm it is slightly recessed,,as-at 11*, to form a sound-chamber. Around the periphery of the plate I provide the rearwardly-extending flange a and the surroundin bead (0", Iflxtcndingfrom side to side and secured at opposite sides to the flange (f is the bridge B. to which the resistance-button is connected. Extending about and inclosmg the bridge and the working ,parts of the instrument theshell .V. which takes overand is secured to the flange o and abuts against the beadathereby producing a ueiltfinish. 'This shell has its'ccntrz'xl portion flattencd. asshown. and provided with suitable apertures, so that it may be secured to the end. of a hollow Sll.])l)0ltl11gtllfl\1 the conductorsv from whiclrinay pass into the shell and bficured to the respective circuitterniil'lals of the instrument. Between the ingparts ofthe transmitter. I These cons ist of the front and back electrodes E and E,

'clgeQB andthe diaphragm l) li'ethe workelectrode E is secured directly to the im'ie'r circular wall of the cup, while the rear electrode E 1s carried upon a-stem c, secured in the stud e, whichiu turn is rigidly held in the bridge. For the purpose of securing this studfirmly and in proper alinemcnt the bridge is provided with a raised boss. I). which may be: integral therewith, but is shown as a. separate piece secured thereto. This boss is centrally drilled to receive the stud and carries a set-screw b, by which it may be locked rigidly in position when adj usted. The electrodes are metal plates with polished hard carbon faces, and between them I dispose granular material, such as carbon in the usual manner; In order to close the casing surrounding the electrodes and also to add to the resilience of the vibrating partsyI provide the auxiliary diaphragm F which I preferably form of mica or other insulating material not readily affectedby heat and of elastic nature. This is in the shape of a perforated disk slipped upon the-stem 'e and firmly clamped between the electrode-plate E and the Hat head of the stud e. The disk extends out around the electrode and overliesthe peripheral flange.

Y scrcwsor rivets.- In' Fig. 1 I have shown the flange and ring riveted together, and in F g. 2 I'have shown the ring threaded and screwed on the flange. The cup C rests with its bottom against the'diaphragin I), being. maintained in intimate contact thcrcuuth by means of springs S S, secured to and extending out from the'flange a and having their inner ends respectively raised upon opposite sides of the ring I usually insulate these springs from the flange a using them as a part of the circuit. for the instrument for making electrical connectionwvith thecup, and thereby one ofthe electrodes. and I may increase or decrease their tension by changing I somewhattheir degree of curvature) They are preferably made of rather stitt' spring metal, such as German silver, and I prefer to make the cup C and the ring 7 of aluminum, so that little is to befearcd from corrosion. In. assembling this instrument the diaphragm is insulated by the soft-rubber band (I, which is sprung around its pcriplicry and is held in'.place by the usual side springs. (Not shown in-' Fig. 1.) The separate damper-springs commonly .used with" thistyp'e oftransformcr I find ;1 do not 'need. the-springs S. performing their function perfectly. I11.-fa(:t,.tl1e damping action of the springs B being s 'mnwtrical and communicated to -the diaphraginovcr a suitable central area is much superiorto that of the. ordinary springs. andfrom this springs a part of the superiority of my in;-

strumentmA-fter the diaphragm is in place the cup Oheld against it by the springs Sand the bridge B, secured to its flange,

; terminals.

enable self-induction in the circuits it is] the correct normal relative positions of the parts are deciently apparentfrom the illustration and description. "The cup Cis not supported 1 upon the diaphragm, noris it positively connected thereto, yet the springs S maintain a sufliciently intimate contact and a heavy enough" pressure to insure most excellent transmission of the vibratory motions of, the dia hragm to the cup and its movable electro e E. It will be observed that the parts are self-centering, that the carbon granules in thecup C are constantly agitated to prevent their packing, and that no abnormal or violent movements of the diaphragm will afiect or the reason that the cup C or its contents, the movements of the cup are limited by the mica disk F, as well as by its own inertia, the latter, however, being small.

In Fig. 2 I have shown a similar construction, with the exception that all circuit connections are insulated from the bridge or the shell of the transmitter. This is a point of some importance in a transmitter to be used in common battery systems, as it is nowcommon to employ potential differences of forty to fift%vvolts between the central-office ith such voltages and considauite possible to obtain annoying shocks in me use of a telephone-as, for instance, by

gasping the transmitter-shell with one n and touching the switch-hook with the other if both are uninsulated as regards the main circuit. By the construction shown in Figs. 2and 3, however,-I do away with all danger of shocks. In these figures the working partsare all the same as described in connection with Fig. 1. Instead of having i the bridge by the springs S extend from the side flange, however, I make these springs in one integral U-shaped piece and secure them-beneath a hushed screw-bolt and nut s s, the construction being such that a strong mechanical connection is produced, as wel as a thoroughly insulated binding-post.

The central boss I) is in this case carried upon a plate I), separated from the bridge post a is a sheet of insulating material, such but attached thereto by the hushed screws b and 1). Between the plate and the bridge and extending also beneath the insulated as hard'rubber, b". The central boss 1) lies in an opening b in the bridge large enough to give a that an accidental contact'in assembling is impossi le. The circuit of the instrument as thus constructed mm the screw 8, double ring S, screw-ring f, flange 0, cup C, electrode E, through the anular carbon to electrode E, throught e stem 6 and the learance all around the boss, so

} stud e' to the boss I) and plateb and out; .I All the vparts included in this circuit are intermined by moving the stud e in the boss 6, p and the adjustment is then rendered'perma- 'nent by setting up the screw 1). The opera ation of this form of transmitter is sufli- 5 sulated, so that the line has absolutely no connectionwith the shell of the instrument.

i tween the diaphragm and the vibrating cup.

The second and third objections are obv1-- I ated by makingthe parts self-centering and l by disconnecting the cupfrom the diaphragm entirely. The-fourth defect is re- 1 moved by supplying. .thetension-springs S, which do awaywith thedead-point. in vibration of the diaphragm.

My transmitter has many advantages not herein specifically mentioned and which become apparent upon considering the method of construction.

I am aware that many changes may be made in matters of detail without sacrificing these advantages as long as the principal it is therefore to be understood that all such changes and modifications are contemplated by me as fully within the scope and perview of my invention.

Having thus described my inventionfivhat I claim, and desire by Letters Patent, is-

1. In a telephone transmitter, a vibrating diaphragm, an independently supported cup resting with its bottom against the diaphragm, the other parts of. the =cup being .i'ree from the diaphragm, an electrode supported by said cup, springs pressing said cup against said diaphragm, a second electrode independently and rigidly fixed with respect to the first and granular conducting material between the electrodes in the cup.

diaphragm, having its edges turned over at an angle to its sides and resting with its bottom against said diaphragm, the cup being otherwise springs pressing the cup against the diaits edges secured to the turned over edges 0 of said cup, an electrode in the bottom of said cup, a second electrode rigidly and independently fixed with respect to the first and Having thus described my invention, it

2. In a telephone transmitter, a.vibrating' 3. In a telephone transmitter, a vibrating an independently supported cup phragm, a supplemental diaphragm having the cup and forming a closure for the mouth overcome'by, the large area of contact be features of the invention are attained, and

springs pressing the cupagainstfree from engagement with said diaphragm,

diaphragm,- a seeon 10 granular conducting material between the electrodes. y a V a 4. In a telephone transmitter, an integral diaphragm, a cup resting with its bottom against and behind the rear surface of said diaphragm and; otherwise free of the diaphragm an electrode in the bottom of said cup, springs pressi the cup against said sup orted independently of said first electro e and granular conducting material between the electrodes in the cup. 1

5. In a telephone transmitter, an integral vibrating-diaphragm, 'a-eup havingits bottom engaging the rear surface of said diaelectrode insaid cup phrag-m and having its edges; turned over but not engaging said diaphragm, asnpple;

mental diaphragm engaging the turned over edge of the'diaphra'gm, springs pressin the cup against the diaphragm, an ,electro e in said cup, a. second electrede rigidly fixed 7.

independently of said first electrode and granular conducting material between said electrodes in said cup.

In testimon whereof I aflix my signature 25 in presence 0 two witnesses.

I Witnesses A. D. '1. LIBBY, C. A, SEVER OOL.

WILLIAM W. DEANQ

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