US1303183A - Henry c - Google Patents

Description

UNiTED sTATEs PATENT OFFICE. Y

HENRY C. EGERTON, OF PASSAIC, NEW JERSEY, ASSIGNOR T0 WESTRN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION 0F' NEW YORK.

PiroNoenAPH-Titnirsnrrrnn.

y* Specification ofLctters Patent.

Patented May 6, 1919i Application mea Maren 13,191'6. seriaiNo. 83,869.

To all whom t may concern.'

Be it known that I, HENRY C.. EGERTON, a citizen of the- United States, residing at Passaic, in the county of Passaic and State of New Jersey, have invented certain new and useful Improvements in Phonograph-Trans' mitters, of which 4the followin is a full,

\ clear concise, and eXact description.

This invention relates to phonograph transmitters, andl more particularly to transmitters wherein currents generated in anelectromagnetic system bythe vibrations of a tracing stylus act in a telephone receiver to. produce speech or other sounds present, as recorded on a phonograph record.

One object of this invention is to provide a highly efficient magneto-inductive current generating system of this character, in which the effective movements of the tracing stylus are of greater amplitude .than the resulting movements of the armature in the magnetoiiiductive system. v

Another obj ect. of this inve tion is to pro-v vide an improved phonogri h. transmitter adapted to be assembled in a small symmetrically formedinclosing case of such convenient shape and size as best adapted to withstand the handling to which phonograph transmitters are necessarily subjected, and to better meet and perform the service operations for which they are intended.

A further object of this invention is to provide an improved phonograph transmitter which may be interchangeably positioned to reproduce sound vibrations from either a socalled vertically grooved record or a transversely grooved record.

In accordance with @this invention a magnetoinductive system, comprising a plurality of pole members, magnetizing coils, and T current' reproducing coils, is provided with an armature of a relatively considerable mass. The armaturerests centrally on one of the pole members, and is adapted to eXecute a rocking motion of limited amplitude in the magnetic' circuit/zone of ythe several pole members, in response to vibrations transmitted thereto by means of a motion reducing leverage system interposed between the tracing' stylus and the `armature. Cuirrents correspondingly varying in strength and direction are therebyinduce'd in the cur rent reproducing coils. Therefore a telephone receiver included `in a circuit with these coils will be operated to repeat the tones represented by the groove on the phonograph record.

In the accompanying drawing, Figure 1 represents, partially in perspective, a side, sectional view of a completely assembled transmitter. Fig. 2 is a similar view showing the transmitter turned one-quarter o'r ninety degrees to the l left of the .position shown in Fig. 1. Fig. 3 is a diagram of the circuit and vconnections of the magneto-inductive system of this transmitter. Fig. 4 shows, on an enlarged scale, atransversely cut groove of a phonograph record, which is the'style of record adapted to'be traced when the trans'- initter stylus is in the position shown in Fig. 1, and Fig. 5 shows a'vertically outl grooye 4of a phonograph record, which is the style of record adapted to be traced when the transv`with that shown in Fig. 2.A

Referring tothe drawing, the reference numeral 1 indicates a casing suitable for mitter stylus is in a position. corresponding inclosing the work-ing parts of the transmitter and also serving as a support for these enter and close the lower end of the casing 1, is attached to the magnetic frame by means of the brackets 9. The diameter of the disk -6 is also less than the inside .diameter of the casing 1; therefore the magnetic system of the transmitter is completely inserted' in the casing 1, in whichV position the disk 6 rests against the inside'surface of the end section of the casing, and the diskS enters and seals the mouth of the casing chamber. An opening 10, centrally located in the upper end portion ofthe' casing 1, serves as a `port through which the `necessary exterior conductors enter the transmitter. A slotted opening 11, locatedat a uniform radial distance from theport 10, extends through a. section ofthe end portion of the .casing 1. A screw-threaded bore extending through the disk 6, and into the frame extension 7, is located in alinement with the slot 11, land.

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therethrough receives a threaded screw 12. The flange or head of this screw is of sufficient diameterto overlap the edges of the shifted to and clamped in either the position shown in Fig. 1, or the position shown in Fig. 2. It Will be understood that this onequarter rotative shifting of the transmitter assembly takes place within the casingy 1 which remains in the position shown in Fig. 1 with respect to the supporting arm 2 and U member 4. In Fig. 2 the casing 1 is shown shifted one-quarter to the-left merely for convenience in showing the manner in which the U member 4 is connected thereto.

In describing that portion offthe transmitter assembly which pertains more particularly to the moving or vibrating parts thereof, a bridge member 14 in the form of a spider is rigidly clamped between nuts 15 carried by four screw-threaded studs 16 which project from and are supported by the disk 8. vA pic-ce of suitable resilient or damping material 17 resting in the bridge member 14, presses a rocking plate 18, having sluitable bearing slots, against the knife-edged ends of two studs 19 carried by the disk 8. The bearing studs 19 engage .the rocking plate 18 near its ends, and in the side view of this assembly, as shown in Fig. 1, are located behind and in alinement with the screw threaded studs16 and therefore do not appear in this view. A bore extending through the rocking member 18 continues upwardly into the extension 20 of this member, and a bore of. great-er caliber in alinement therewith through the bridge A14, and the damping material 17 permits the shank of a stylus 21 to be inserted therein. The caliber of the bore through 14 and 17 gives entire clearance for the shank of the stylus 21, while the bore through 18 and 20 is of a caliber into which lthe stylus 21 is adapted to form a suitable fit. A set screw 22 carried by an enlarged base portion of the extension 20 and located at substantially the axis of rotation of vthe plate 18 serves to secure the stylus 21 rigidly to this plate. By locating'thescrew 22 at substantially the axis of rotation of the plate 18 and extending the stylus across this axis the movement 'of inertia. of this portion of the lever system is materially reduced. A bore `23, extending centrally through the disk 8, is of a caliber suiiiciently large to permit clearance for the member 20, which extends therethrough into the casing 1. A section of spring wire 24 serves to form a meclranical connection between the member 20 and an extension member 25 of an armature 26, the wire 24 being' rigidly connected to each of the members so joined. The armaon the ole member 28. Two curved s Jrino's' 32, rigidly attached to the bridge membert). are adapted to rest on rthe spool heads of magnet poles 27 and 28, and exert pressure to retain the spools in position.

In the magnetic system, the windings 38 and 34 connect to a suitable source of uni-' directional current (not. shown) and serve to magnetize the pole members 27 and 29. The resulting magnetic iux completes circuit through the armature 26 and the common pole member 28 located midway between and acting magnetically differential with respect to the two pole members 27 and 29. T he windings 35 and 86 respectively associated with the poles 27 and 29 represent the current reproducing coils, and when connected with a telephone receiver circuit (not shown), generate currents therein which correspond in strength and direction with the amplitude, rapidity and direction of movement of the armature 26, all in a well-known manner. Suitable terminals 37, 38, 39 and 40 are provided for terminating the windings 33, 34, 35 and 36, and for convenience in connecting the exterior conductors thereto.

In describing the operations which take place in transmitting vibrations from the stylus 21 to the armature 26, let it be assumed that a phonograph record grooved as shown in Fig. 5 is traveling from left to right and in proper Contact with the stylus 21, the transmitter being held in the position shown in Fig. 2. The vertically formed indentations of the record-groove cause the stylus to be vibrated in a direction parallel to the direction in which tthe record is mov-- ing. Accordingly, the plate 18 rocks to and fro on the knife-edged bearings of the studs 19, and by means of the extension 20, alternate push and pull stresses are applied longitudinally to the spring wire member 24, which in turn sets up reciprocating or rocking movements of the armature 26. These movements of the tracing stylus 21 represent the tones which it is desired to reproduce.l and as the spring member 24 is of such proportions as not to be appreciably flexed or buckled when push stresses are applied thereto longitudinally, it will be apparentthat the effective vibrations are transmitted 'from the stylus 21 to the armature 26 over connections in whichelastic losses are prae-v tically avoided. In case the stylus is caused to vibrate in a direction at right angles to the travel of the record, 'however,'s'uch vibrations, provided they are not absorbed by the damping material 17, produce'transverse stresses on the spring member 24:, which is suiiiciently flexible to yield thereto.' Accordingly these transverse vibrations are absorbed and not transmitted to the armature 26. This feature results in eliminating such .vibrations as do no-t form a part of the ltrue phonograph record, thereby materially improving the distinctness and tone quality of the soundsreproduced in the telephone receiver.

From the foregoing description in connection with the vertically groved record, it will be apparent that when the transmitter is positioned as shown in Fig. l and a transversely -grooved record similar to that shown in Fig'. i is traced, the effective lateral vibrations of the stylus 21 will be transmittedl to the armature 26 and any vertical vibrations will be absorbed by the spring24. l

In lthe matter of connecting the stylus 21 to the rocking plate 18, it will be noted that the set screw 22 and the enlarged portion of the extension 20 into which it is threaded, are practically in alinement with the bearing point present between the rocking plate 18, and the knife-edged bearing studs 19. This feature reduces toa minimum the inertia eect ofthe set screw 2v2, thereby materially increasing the effectiveness of the transmitter.

A further advantage of the present invention relates to the double motion reducing leyerage system, the first of which-is present w1th the rocking plate 18 whereby the point of the stylus 21, in tracing arecord, moves a greater distance than the resulting movement at a point on the extension 20 at which the spring 24 is attached; the second motion reducing system being present withl the ar- I mature extension member 25 which reduces ,at the point o f the stylus 21. This eature. has an appreclable effect in overcoming thethe amplitude of the movement transmitted thereto by the spring member 24. Accordingly, the movement of thearmature l26 is considerably less than the initial movement inertia and any momentum tendency of the necessarily heavyv armature, and results'in a considerable gain in the articulation and quality of tone reproduced. A further advantage of this double-levering system,

which acts accumulatively, is to make 1t possible to condense the assembly of the transmitter and inclose it in a. casing 'of relatively midget proportions, as shown and desorfibed. In order to protect the transmitter whereby said armatureis moved less than vsaid stylus upon movement of the latter.

2. In a compact phonograph transmitter, a stylus, a magnet, an inductive current circuit for said magnet, an armature for'said magnet, ,a plurality of compact motion-reducing leverage systems for connecting said stylus withisaid armature whereby said ar,-

mature is moved less than said stylus on movement of the latter, and a compact cas; ing adapted to inclose and support the com-l pletely assembled parts of said 'transmitterll 3. In a phonograph transmitter, means, for generating electric currents, a stylusg means for transmitting vibrations from said stylus to said current-generating means, a casing adap-ted to inclose and support said transmitter, means for assembling said' transmitter independently of said casing, '95 4 and means for changing the position of sald transmitter withinsaid casing to adapt said `transmitter to trace either a vertically 'grooved record or a transversely groove'd record. I

.4. In a phonograph transmitter, a stylus, a plurality of magnet poles,'current inductive circuits for said ma'gret poles, anarmature for said magnet poles adapted to be operated by said stylus, and a central tra-nsverse ridge formedon the face of said armature adapted to seat on one of said magnet poles and permit said armature to execute a rocking motion thereon'in the iiuX zoneof said magnet poles.

5. Ina phonograph transmitter, amagneto current-generating system, `a stylus, a plurality of motion-reducing systems adapt-ed to transmit vibrations from said stylus to said magnetic system whereby vibrations' transmitted to said magnetic system by movement of said stylus are of smaller amplitude than corresponding vibrations of said stylus, and resilient dampingmaterial adaptedto retain the working parts of said transmitter in their respective operating positions. f

In witness whereof I hereunto subscribe 'my name this 10th day of March, A. D. 1916..

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