US1602824A - Telephone receiver - Google Patents

Description

Oct.. 12 1926.

L. L `JONES TELEPHONE RECEIVER Z.. fw

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BY l v MfWMMTToRNEx/c zov Patented @et l2, lg.

L. JONES, OF NEW" YORK, N. Y., SSIGNOR TO POWERFONE COMPANY, 0F NEW i RK, Y., A PARTHERSHISP COMPOSED JNES, AND ALLEN D. GARDWELL.

F WILLIAM DUBILIER, LESTER L.

' TELEPHONE RECEIVIEJR.

application mea may a, ie'aav serial iro. 557,838.

The invention relates to an instrument for transforming electrical impulses into sound waves, such as telephone receivers `and the like,.and the features of the invention, although of quite general application, are particularlyuseful in connection with receivers "operating with substantial amounts of power, and adapted to produce sound wavesv of large volume.-

One object of the invention is to provide a receiver of the above type wherein the magnetic circuitsare so related aswto -be highly sensitive tochanges in electrical impulses impressed thereon, whereby the sound wave generating diaphragm which is operated by changes in the magnetic circuit. may lbev caused to produce distinctly and sharply the sound waves corresponding to different electrical impulses.

Another object is to construct the instrument so as to permit the armature vwhich operates the sound-producing diaphragm,

to be intimately related to the pole pieces vof the magnets with which it cooperates, and yet without danger that thev slight spacing betweenV such armature .and the pole pieces will be likely to cause stickingof the armature between or against the same. It is also desired to employ a magnet structure ,which will decrease the length of the armature iuX path by permitting the pole pieces which influence such armature, to be set very closetogether.'

'The invention also aims to enable the use in receivers of the above character of diaphragms whichV are exceedingly thin, flex`- ible and of, light weight, and therefore capable of responding sensitively to changes vin the magnetic field, but under. such -conditions that a large gap need not be em ployed in connection with the diaphragm to insure that the impulses are transmitted to. a relatively large area thereof, or to prevent sticking against' thegpole pieces.

Another object is 4tosegregate,4 .soto speak, the variable magneticcircuit of the receiver froin'the .constant magnetic circuit thereof so as to enable each of such circuits .to react eihciently upon the'diaphragm, and `eliminate losses which might-occur .due to interaction between such circuits.

Another Objectis to provide a receiver wherein a sound-'producing diaphragm and an armature. for actuating same are so combined and related to the magnetic circuits of the receiver that the magnetic forces` will produce a maximum effect upon the diaphragm. A y

c The invention also aims to permit energy transfers from the soundproducing .diaphragm t'o the surrounding air without the generation of objectionable resonance tones,

by employing a diaphragm which 'communi Cates with the outer-'air through an opening of relatively large area. y

Further objects and advantages of the invention will be in part obvious and in part speciiically pointed out in the description hereinafter contained, which, taken incon- Y ing operatively related to the parts of the receiver which appear in Figs. l to E.v

Fig. 5 is a diagrammatic view illustrating a mo'dication of certain features of the invention. I

Referring to the drawings, a telephone receiver is illustrated 'having a permanent magnetic circuit embodyingga magnetl,

-which may be of any convenient shape, and

which in the present instance is shown as of the horseshoe type, having Vpoles 2 `and 3, between which are located pole pieces/t vand 5 lwhich will .belmore Ifully described hereinafter. In the' illustrated embodiment of the invention the-magneto motive .force of the above-mentioned magnetic circuit is obtained entirely from the ermanent magnet l, which ispreferably otp relatively large power, whereby. the flux emanating therefrom constitutes a relatively large fraction of thetotal ux which influences the soundproducing diaphragmof the receiver.

In connection with the above-mentioned magnetic circuitthere is employed a variable magnetic circuit, which in the present yform is made up of leg 6 integral with the pole ico piece previously described, and extending across the inne'r face of pole piece 3 of the l permanent magnet, and a further magnetic permanent or constant-magnetic circuit, and, the variable or branch ,magnetic circuit' which is affected by `coil 9. This last-mentioned circuit is later referred to as being in parallel with the permanent or Aconstant magnetic circuit, since permanent flux passes, for example, from pole 2 to pole pieces 4 and 7, and across gap 10 to pole piece 5 and pole 3; it should be noted however that the above arrangement also provides a parallel path for the permanent fiux which includes elements 2, 4,7, 8, 6 and 3 and in a parallel path 7, 8--14, 6, 3.

The magnetic system is so arranged as to maintain substantially constant iux in the magnetic circuit, comprising magnet 1, by including a portion of relatively hi'gh reluctance in such circuit, which is in series with pole pieces 5 and 7, and' the variable magnetic circuit. As shown in Fig. 1, thisA portion of high reluctance takes the form of a flux-limiting gap 11 interposed between the ole pieces 4 and 5, which gaplimits the totalD amount of flux passing through the permanent magnetic circuit, and xes the I amount of permanent flux passing across the ga 11, regardless of the changesl in the variab e ma netic circuit which are produced by coil)r 9.

The provision of a high reluctance portion such as gap 11, in the permanent magnetic circuit, opposes any tendency of the iuX from the variable magnetic circuit passing around through permanent magnet 1, whereby hysteresis and eddy current losses are avoided in the magnet 1, due either to changes inthe permanent fiux, or thepassage of flux therethrough which is generated by coil 9. Thus with circuits of the above nature the pole pieces 5 and 7 and the ele-l ments 6 and Smay be laminated as indicated in Fig. 2, to cut down the losses in the variable magnetic circuit, but the permanent magnetic circuit, which may not be very readily constructed of laminatedv pieces, will not vcause increased losses due to flux variations therein.

. Fig. 5 illustrates a modication of this idea, wherein a permanent magnet 1I1 is provided with `poles `2a and 3, and pole pieces 7n and 4 carrying f1uX-varying coils 9El and 9, which are mounted on the poles 2a and 3"' respectively, together with legs 82L and 6*1 extending between the poles 2a and 3a to provide a shunt path for the variable magnetic flux produced byy coils 9cl and 9". In this instance the flux passing around through magnet 1a is limited by means of short circuited loops 12 and 13 of copper or the like enclosing the poles 2a and 3a, which members 12 and 13 oppose the passage of variable ilux around through the magnet 1.

.Referring again to the embodiment of the invention illustrated in Figs. 1 to 3, the variable magnetic circuit is also provided with a portion of high reluctance, such as air gap 14, in the present instance interposed between the legs 6 and 8 previously described, to balance the iux passing through the permanent magnetic-circuit, and to insurethat a proper proportion thereof will pass across the gap l()V between pole pieces 7 and 5.

"It is obvious that the short-circuiting means such as the loops 12 and 130i1 copper or the like, shown in Figure 5, may be applied to the embodiment of the invention illustrated in Figures 1 to 3. Here the shortcircuiting loops may consist of rcopper or the like arranged in the position shown in Figures 1 and 2 and indicated by the numerals 12u.

It will be noted that coil 9, being located in theshunt part of the variable circuit, has no effect upon the permanent flux which passes across the gap 11, but serves to divert a variable portion of the per* manent fiuX through gaps 10 and furthermore this coil being located in the shunt part of such circuit does not require a spacing be- 'tween the pole pieces 5 and 7 conforming to theldimensions of thecoil. In other words the pole pieces 5 and 7 may be set very close together, so as to reduce the reluctance of armature 15 and its weight, as contrasted to a structure, for examp e, as illustrated in Fig. 5, where thepole pieces 4 and 7l1 are spaced a distancecqual to or greater than the diameter of one of coils 9a or 9b.

The disposition of the coil 9a in the shunt partof the variable magnetic circuit also avoids thenecessity of employing two coils of this nature, as has oftembeen done.

In the illustrated embodiment of the invention a separate armature 15 is disposed adjacent the pole pieces 5 and 7 and connected to the diaphragm 16 (Fig. 1) to move the latter in accordance with the variations in flux between pole pieces 5 and 7. The armature 15 is enabled to be spaced viery slightly from the pole pieces, as hereinafter described in greater detail, andas such pole pieces are set very close together, the length and reluctance of the armature, are very small. For example, the armature air gap may be ten thousandths of an inch, and the Lacasse distance betweenfadjacent surfaces of the polepieces and 7 need not be greater than sixty thousandths of an inch with; the armas.

mensions so related to the magnetic forces acting thereon that the ratio vofmagneticpull tothe weight of the armature may be substantially at a maximum. The condition is substantially satisiied by the lequation lL= 1/ 8 l M G, where L is the dimension of Athe armature in the directionwof the flux, T the thickness of the armature,l\ the permeability of the armature, and G the normal distance between the armature and the pole pieces. Thus the magnetic lux passing through the armature will be relatively large, while the mass or weight of the armature is relatively small, resulting in the ap'- plication of efficient forces to the diaphragm 1G to influence the same. f

The pole pieces 5 and l7 are also preferably so shaped and related to the remainder of the magnetic structure' as to concentrate the iiux between the polepieees, in the region of the armature 15.. As shown, the surface 5al of the pole piece 5, which opposes pole piece 7, is beveled back, or tapered toward the Y armature, while the surface/f7? ofthe pole piece 7 is also cutaway to Adirect the major portion of the lux in pole 'piece 7, through f the opposite portion of such pole'piec'e which '35 is adjacent'the armature.' As appearsin l Fig. 1, the cross sectional area ofthe pole pieces 5 and 7 furthermore preferably is made relatively small, with respect to thev remaining magnetic parts of the magnetic circuits including such pole pieces, whereby the flux density in the pole piecesis relatively greater or more concentrated. It is also preferred toemploy a diaphragm 16, the effective weight in motion of which is substantially equal to the weight of the armature. If a heavier 'diaphragm is employed the motionimparted thereto when the armature is actuated by the magnetic forces, is relatively small, while if the diaphragm is too light, the forces of the magnetic pull are transmitted onlyto a relatively small fraction of the area thereof.

In order to permit the -use of a very small air gap between the armature 15 and the pole pieces. 5 and 7, without danger of the armaturesnapping over against or sticking to the pole pieces, -it is also preferred to apply .external forces to the armature 1.5, urging the same in the direction ofthe magnetic"A pull. In the present instance, the armature is connected to diaphragin 16 at its intermediate portion, and suitable means. such as metallic threads '16a (Figs2 and 3) are afxed to the ends of the armature and placed 05 under tension as bysuitable binding'scr'ews 17. Then the screws 17 are tightened up to apply tension to the threads 16a, the armar,

ture 15 is pulled toward the pole pieces, and the diaphragm 16 is flexed as indicated in Fig. l. Threads lliejin the plane of the' gap when the armature touches the poles .so'

that they no longer urgel armature towards A l pole. i The combination of this rapidlydisappearing gap closing force with the dia'- phragm reaction, presents a rapidly 'increaslng resistance to further flexure, thus coun- 'teracting the tendency of the increased magnetic pull as the armature approaches the pole pieces, to stick the armature against the same. Preferably the forces exerted by the threads l upon the armature when the ar,-

'mature is inits operating position are greater than the maximum magnetic pull which may be imposed-upon the same for any ar mature gap length, to insure vthe maintenance of 'the air gap between the armature and the pole pieces under all conditions..

Where an armature spaced from both pole pieces is employed, as in the case of the'illustratedl embodiment, it is preferred to so connect the armature to the diaphragm'l as to permit equalization of forces Vapplied thereto by the threads or members 16a. In the present instance, a hooked rod 18, fixed to' the diaphragm, engages with a bridle 19, having its end fastened to the armaturein Such manner that the stresses, imposed upon vthe opposite ends ofthe armature by threads 1621 become balanced, to 'provide against one end of the armature snapping-over against its corresponding pole piece due to unequal stress distribution.

The initial lexure of diaphragm 16 asy above described, also permits the eliicient vuse of a large diaphragm, 'which diaphragm may yet be fvery thin, and' therefore flexible and sensitive, and of4 lightweight. If athin and flexible diaphragm -be employed eol under ordinarycircumstances, since the diaphragm yields readily,` a large' airfgap might have to be 'employed to .prevent the diaphragm or its armature'from snapping over or sticking to the. pole pieces, and further-- more the flexibility of the diaphragm might bring about the result that the magnetic attraction .of the armature would affect only 'a' relatively small part of the area of the'diaphragm. But if the diaphragm be initially flexed, a very small air gap nevertheless may beV employed as above described, and

the tension upon the material of .the'dia-A phragm insures that the magnetic forces will be transmittedover the major portion izo of its area. .The diaphragm may beco'- structed of very thin steel, and the invention 'also makes possible the use of readily stretchable materials such as paper, or hide,

sincethe tension on the diaphragm makes it taut to a much greater extent than would be possible merely by magnetic pull. Thus occur if a very thin. iexible diaphragm were.

the higher tones (those above two thousand cycles) are vnot lost, which otherwise might used.

lAs isillustrated in Fig. 4, the magnet structure-and diaphragm may be mounted within a suitable casin 20, the edges of the diaphragm being held etween the adjacent wall of-the casing and a ring 21 overlyingA the same. The diaphragm 16 is also preferably placed in communication with the outer air either directly or through a horn or the like 22, having an opening substantially equal in area to the area of the diaphragm; thus resonance chambers are avoided, permitting the energy of the diaphragm lto be transferred to the .surrounding air without the generation of resonance tones.

While aspecific embodiment has been disclosed, it will be obvious that many changes may be made therein without departing from the principle of the invention, as de- `fined in the appended claims.

motive force, a branch magnetic circuit in parallel therewith, a sound reproducing diaphragm, said circuits having pole pieces 4adapted to influence said diaphragm, and a coil inductvely related to said branch circuit, said branch circuit having portions of high reluctance at its opposite ends separating the saine from the first-mentioned circuit.

3. A telephone receiver comprising a sound reproducing diaphragm, a magnetic circuit, and a branch circuit in parallel therewith, said circuits having pole pieces' to influence said diaphragm, the branch 'circuit including portions of high reluctance separating it from the first mentioned-circuit.

4. A telephone receiver comprising a sound `reproducing diaphragm, a magnetic circuit, a branch circuit in parallel there with, said cicuits having pole pieces to influence said diaphragm, the branch circuit having portions of high reluctance separating it 'from' the rst mentioned circuit, and means forvarying the eiiect of the branch circuit.

5. A telephone receiver com rising a magnetic circuit of predetermine magnetic motive force, a branch'.inagnetic circuit in incassa.

parallel therewith, a soundreproducing diaphragm, said circuits having pole pieces adapted to infiuence said diaphragm, and a coil inductvely related to said branch cirphragm, said circuits having pole pieces adapted to influence said diaphragm, and a coil inductvely related to said branch circuit, said irst-mentioned circuit having an air gap therein in series with said branch circuit. v

7. A 1 telephone receiver comprising a magnetic circuit of predetermined magnetic motive force, a branch magnetic circuit,l in parallel therewith, a sound reproducing diaphragm, said circuits having pole pieces adapted to influence said diaphragm, a coil inductvely related to branch circuit, said first-mentioned circuit including a portion of relatively high reluctance in series with said branch circuit, and the branch circuit also having a portion of relatively high reluctance therein..

8. A telephone receiver comprising a magnetic circuit, and a branch circuit in parallel therewith', a sound reproducing diaphragm, said circuits having pole pieces to inuence said diaphragm, and said first circuit having a portion of relatively high reluctance in series with the branch circuit.

9. A telephone receiver comprising a flexible diaphragm, pole pieces adapted to in- 1iiuence the same, and balancing means for exerting a force additional to the magnetic pull from the pole pieces tending to flex said diaphragm in the direction of the magnetic pull, said means exertin a force on the diaphragm greater than t e maximum magnetic pull.v

10. A telephone receiver comprising a l flexiblev diaphragm, an armature connected thereto, pole pieces adapted to influence said armature, and balancing. means to exert a force additional to the magnetic pull from the pole pieces tending to urge said armature inthe direction of the magnetic v pull, said means exerting a force on the diaphragm greater thanthe maximum magnetic pull.

11. Atelephone receiver comprising a iiexible diaphragm, an armature connected thereto, said diaphragm and armature being substantially equal in weight, and pole pieces adapted to influence said armature.

12. A telephone receiver comprising a iiexible diaphragm, an armature connected thereto, said diaphragm and armature being substantially e ual in weight, pole pieces adapted to in u'ence said armature, and

means additional to the magnetic pullgfrornit i the pole pieces for urging said armatireii the direction of themagnetic pull to flex the diaphragm, said means exerting a force larger than the maximum magnetic pull.

13. A telephone receiver comprising a iexible diaphragm, an armature connected thereto, pole pieces adapted to intluence said armature, said armature having dimensions so related to the magnetic eld passing through the pole pieces4 as to produce substantially a maximum ratio of magnetic force to the weight of the armature.

14. A telephone receiver comprising a magnetic circuit of predetermined magneto motive force, a branch magneticcircuit in parallel therewith, said first-mentioned circuit having pole pieces adapted to iniuence a iaphragrrn and an armature adjacent sai having a pole disposed adjacent said armature and being separated at a point remote from said armature by a portion ofhigh reluctance from the lrst circuit.

15. A telephone receiver comprising a magnetic circuit of motive force, a branch magnetic circuit in parallel therewith, said rst-mentioned circuit having pole pieces adapted'toA influence a diaphragm, and an armature adjacent saidpole pieces, said branch circuit' having a pole in pointrremote from said armature by a portion of high reluctance from the iirst-mentioned circuit, said pole pieces being small in cross section when compared to the remaining portions of the magnetic circuit associated therewith.

16. A telephone receiver comprising a magnetic circuit of substantially constant magneto-motive force, a variable'magnetic circuit in parallel therewith, said circuits pole'pieces, said branch circuit also predetermined magnetol larmature spaced therefrom,

proximity to the armature, andn being separated at a having pole pieces in common, and an armature adjacent said pole pieces, said pole pieces being spaced a distance not greater than the order of three times the length of the arma-ture air gap.

17. A telephone receiver comprising a source of magneto motive force, pole pieces of opposite polarity in adjacent positions, an armature in proximity to said pole pieces, and an additional pole piece having one extremity located between the firstnamed pole pieces, and havingits opposite extremity .separated from one of said firstnamed pole pieces by a gap of relatively high reluctance.

18. A telephone receiver comprising a source of magneto motive force, pole pieces of opposite polarity in adjacent positions, an armature in proximity to said pole pieces, an additional pole ,piece having one end adjacent the first-named pole pieces, and having its opposite end separated from one ofsaid pole pieces by a gap of relatively high reluctance, and a closed conductor of relatively low resistance mounted on one of said pole pieces.

19. telephone receiver comprising a magnetic circuit with operating poles, an

members urging the armature towards the poles but not in contact therewith, a diaphragm, a connection between the armature and the diaphragm adjusted to strongly tense the diaphragm and to pull the armature away from the pole pieces, the tension in said connection being greater than the maximum magnetic pull on the armature. In testimony .that I claim the foregoing, I have hereunto set my hand this 18th day of April, 1922.

LESTER L.` JONES.

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