US1934857A - Phonograph pick up - Google Patents

Description

Nov. 14, 1933.

w. H. HuT'n-:R 1,934,857

PHONOGRAPH PICK-UP Filed Oct. 13, 1930 3 Sheets-Sheet l Nov. 14, 1933.

W. H. HUTTER PHoNoGaAPH PICK-UP Filed Oct. 13', 1930 y 3 Sheets-Sheet 2 Nov. 14, 1933. w H. HUTTER 1,934,857

PHONOGRAPH PICK-UP Filed 001.. l5, 1930 3 Sheets-Sheet 3 Patented'Nov. 14, 1933' Y vPHONOGRAPH PICK William YllI. l Hu'tter, Racine,A Wis., assignor to Webster Electric Company, -Racine, Wis., a .fcorporationof Wisconsin Y' n; Application'Qctober 13, V1930. Serial No. 488,243 I s Claims.- (Cl.-1797100.41)

This inventionrelates-in general to reproducing devices or p'honographs and has more particular reference to a phonograph pickup for translating mechanical movements into electrical impulses which may subsequently beV reproduced by the phonograph. w v

A primarypbject of thenvention is the .provisionof an improved phonograph pickup or translating device for use in sound reproducing devices f110- or phonographs- An important object ofy the invention is the provision of such a phonograph pickup ortranslating device including a generating assembly havf ing an adjustable gap between the pole pieces and 15, the armature.

Another important object ofthe present' invention is the provision of a novel rphonograph pick-V up having a vibratorymember so pivoted between magneticpole pieces that the movement of said 29 member isaccurately andeflicientlyvconverted which are so designed, and lassembled that the 1 mean magnetic path will beofjminimum length. Y

A further important object ofthe present invention is the provision of azyoke assembly for electrical phonograph pickupswhich is'piovided with polepieces of such shape as to provide a fulcrum for cam levers `movably secured to the pole pieces and adapted to adjust resilient members l carried by the pole pieces whereby to adjust the pressure on the armaturearranged.betWeensad pole pieces. A i f' OtherA objects andV advantages will appear'more fully from the following description and from the accompanyingdrawings, in which similar characters of referenceindicate similar parts throughout the. several views. j. f' y t In thedrawingsz-l Y Fig. 1 is a side view of ar phonograph pickup or translating device embodyingfeatures. of the iniy 'vention; f Y Fig. 2 is afront elevation ofthe phonograph pickup shown in Fig. 1-, withparts brokenr away;

Fig. 3 is a longitudinal-'section taken substantiallyon the line 3-,3 of Fig. 2 ;y Fig.- 4 is a horizontal section taken substantially on the line 4 4 ci Fig. 3;

Fig. 5 is a section taken substantially onthe line 5,-5 of Fig. 3;V f I Fig. 6 a sectionftaken substantially on Vthe line-6 6 of Fig.4; 4.

Ya pivotal mountingfor'a vibratory member or Fig.- 7 is an enlarged perspective view of a lever member for adjusting the pressure on the armature of the phonograph pickup shown-in Fig. 8 is an enlarged perspective view of a portion Vof the yoke employed in the translating device of the invention-and Vshows certain assembly details; Y

Fig. 9 is an enlarged perspective Yviewof the vibratory member employed inthe translating device oi the invention; Y

Fig. 1 0 is a perspective viewrof a portion of the yoke employed to bridge the magnet of the novel phonograph pickup,vand

--Fig. 11 is aperspective view oi a resilient mem- 70.

c ber used to mountv thearmature of Fig. 9.v i

The present invention contemplates briefiy an improved translating device or phonograph pickup of the electrofmagnetic type which is provided with a YyokeA surrounding .and carrying a generator coil and extending between or bridging the poles of amagnet. This yoke comprises pole pieces carrying non-magnetic members for adjustably spacing the pole pieces and for vproviding armature extending through the coil to vary the gap between the pole pieces at the opposite sides of the coil; the pivotal axis of the armature be ing between the two gaps at the opposite ends of thecoiLf r85 Thisfvibratory member or armature is actuated .bythe stylus or needle of the phonograph in playg V'ing' af record and reciprocates between the pole vpieces atthe-oppositesides of the coil. This vibrationor reciprocation ofY the armature Varies thereluctance of the magnetic vcircuit whichY inducesfV a "current l in the generator coil correlated .to the "mechanical movements of Lthe needle or I stylus fproduced'by therecord. These variations in` current may beamplied and'converted into 95 soundwaves in a wellknownmanner.

To accomplish the foregoing objects a casing 1 5 comprising a base or mounting plate 16 and a cover member 17 is secured at an end of a tubular Y arm ortone arm 1 8' by means of mounting-screws 19 and encloses a generating. assembly', generally designatedbythe reference `character 21. The casing maybe made of any suitable non-.magnetic material such as aluminiun.y

The generating assembly21 includes a U-shaped magnet 22,- preferably of the permanent magnet type .mounted on the base, plate 16 by means of a strap or tie plate 23and a screw 24 threading vintothe plate 16.` The strapj23 is provided with taining screw 25 threads to hold the cover member 17 to the plate 16. A magnetic yoke generally designated by the reference numeral 26 surrounding a generating 'coil 27 provides with the coil a unitary assembly extending or bridging between the poles of the magnet 22. This unitary assembly is secured to the base plate 16 by means of through bolts or studs 28 and nuts 29 arranged at each end of the yoke 26 to hold it adjacent the poles of the magnet.

The coil 27 is illustrated, particularly in Figs. 1 and 5, as being or" greater diameter than the width of the yoke 26 and extends beyond the yoke laterally into a recess 3l provided. in thevbase plate`16 for that purpose. A terminal block or strip 32 is mounted on a stud 33 integral with the base plate 16 by means of a screw 34.*and carries a plurality of terminals 35'connected to the coil 27 by conductors 36. The terminals 8,5 may be connected by conductors 37 in the tubular arm 18 to a suitable amplifying device the output of which is converted into sound waves'.

Thelmagnetic yoke 26 Vis constructed and assembled as shown in Figs. 5 and 8 to provide magnetic pole pieces 38 and 89 which are substantially U-shaped to accommodate the coil 27 and to provide a mean magnetic path of minimum length. The pole piece 38 comprises a side member 41 spaced apart from a side member 42, the side members 41 and 42 being connected by an integral end piece 43 to provide a short magnetic path between the side members which extend therefrom at a pole of the magnet 22 to substantiallycentrally of`r the coil 27, the side members 41 and 42 being reduced in width to provide pole tips 44 and 45respectively at opposite ends of the coil, and a shoulder 46. In like manner the pole piece 39-is providedfwith side members 47 and 48 kand an integral end piece 49. 'These side members are constructed with pole tips 51 and 52 and shoulder-53 respectively corresponding to the pole tips 44 and' 45 and the shoulder 46. y f

Non-magnetic members 54, shown more particularly in Figs. 8 and 19 of any suitable shape such as channel-shaped, are formed withspaced sides 55 which are receivable in alignedslots 56 in opposite sides of the pole pieces A38 and 39 to hold the pole pieces in such an' adjustable position as to provide a small adjustable space or gap between pole tips 44 and 51 and a larger adjustable gap or space between pole tips 45 and 52. The screws 28, passing through aligned slots 57 at each end of each member 54 and the holes 58 and 59 in the pole pieces 38 and 39 respectively hold the yoke assembly in assembled relation adjacent the poles of the magnet 22.V The slots 57 at the ends of thenon-magnetic members 54` extend longitudinally of.` the members 54 and permit adjustment of the pole pieces to vary the distance or gap between pole-tips44 and 51 and the gap between pole tips A45 and52 to adapt the generating unit to various magnetic and playing conditions.

The face of each'channel member`54 is cut away or apertured as' at 61 to accommodate the coil 27 having a larger diameter than the width of the pole pieces. These channel members serve as a mounting for a vibratory member or armaor spring 65 having a knife edge 66 which engages a side 67 of an aperture 68 in the armature tips 45`and 52 and to permit the adjustment of the pole pieces 38 and 89. The coil has its end 72 grooved as at 73 to accommodate the grooved portions of channelvmembers 54 for this purpose.

At one end of the armature 62, a rectangular projection or lug 74 extends beyond the sides of the pole-pieces l38 and '39 and is provided With a bushing 75 to separate the armature from the cover member 17. This projection registers with a slot or opening 76 in the cover member through which-,a needle or stylus 77, held therein by a retaining screw 78, projects forengaging and playing a record.Y This.k end of thearmature. substantially lls the larger. gapbetween the pole tips r45 and 52. The other end of the. armature is reduced in thickness as at 79 andfis4 adapted .to reciprocate between lpole tips-44.and.51 .as-.the armature vibrates orreciprocates about its pivot.

The grooves 64 in the channelmembers; 54 are located midway between the pole pieces 88 and 39 and have a depth sufficient to establish the axis of the pivot of the armature between the gaps formed by the pairs of spaced pole tips. This' arrangement of the armature pivot between the .air gaps and theconstruction of pole Apieces 38 and 39 to provide short magnetic paths magnet.

The reluctance of the air gaps between the reduced end of the armatureand the pole tips 44and 51 and between theopposite end of the armature and the pole tips 45 and 52 will vary as the armature vibrates. As the end 79 of the armature approaches nearer the pole tip 44, the reluctancethroughthis pole tip, armature 62, and the pole tip, 52 will be decreased and the reluctance through-the pole tip 45, armature 62, and the pole tip 51, will increase, thereby permitting the magneto-motive force of the magnet to impress a flux upwardly through the. armature Vas Viewed in Fig. 5. A flux having a direction downwardly through the armature is set up in the magnetic Vcircuit as the armature moves in the opposite direction. This vibration of the armature producesacorresponding variation in the flux in the armature, which induces a current in the coil 27, the wave form of which bears a denite relation to the vibrations of the armatureor -the' needle 77 carried thereby.

Thus pole pieces 38 and 39, the coil 27,'and the 14 armature -62 vare assembled as a unit by means of the channel shaped members 54-and the resilient member-65 which pivotally support the armature on an axis between the gaps formed` by the pole pieces. This unit may bemounted on the plate 16 by the studs 28' and Vthel nuts 29 for testing and removed foradjustment of the gaps between the pole tips and' the'v armature. These gaps between the poletips andthe armature at opposite ends of the coilv27 are adjust- 150 pieces along the channel sidesjvengaging'fin sof the-slots 56 of the pole ipieces.' v.Whenthe gaps have-been adjustedto suit the magnetic circuitv and to provide a desired tone'or to suit anyv desired magnetic or playing. condition .the screws 71 may be Vtightened and the .unit again mounted on the plate 16 by the studs 28and thenuts 29. The `knife edge support-for the armature 62 makes an efficient damping means possible for the armature and thereby `permits the use of the resilient member to provide a yieldable and substantially motionless bearing for the armature of this novel adjustable unit or yoke. This damping of the armature 62 isaccomplished by resilient material 82 in slots 81 which are vformed in the adjacent ends of the pole tips 44 and 5l by a round tool to provide a circular section whereby to prevent the 'resilient material 82 from working out sidewise. This resilient material 82 engages the free end 79 of the armature to maintain the armature in the normal position centrally of the gap between the pole tips 44 and 51.

Each side member 41 and 47 carries a lever 83, see Fig. 7, having a handle 84 accessible when the cover member -17 is'removed to adjust the pressure-exerted against the armature by the resilient material 82. These levers 83 are carried on the pole pieces v38 and 39 by mounting screws 85 engaged by cam slots 86 for guiding a I dependingfinger or lug 87 extendinginto each slot 81 for engagement with the resilient material 82, to vary the pressure exerted Vthereby against the end 79-of1 the armature. The movement of the lever 83 Yis accomplished about a depending lug 88 fulcruming against the shoulders 46 and 53. y

VThe pole tips 44 and51 attract the armature in accordance with its proximity to a vpole tip, but the resilient material82 applies a force tending to return the armature 62 to its central position, which also increases; with the proximity of the armature to a pole tip so that the magnetic attraction ofthe larmature is counterbalanced by the resilient material and therefore willl not eifect the movement of the armature.'

In operation the stylus or needle is vibrated in playing a record. This vibration of the stylusr is transferred or communicated to Ythe armature 62, causing the reduced end '79 to reciprocate vbetween the pole tips 44 and 51 andthe lother end ofthe armature to reciprocate between pole tips 45 and 52. The magnet 22 sets up a magneto-motive force between the pole pieces -38 and 39. The ilux rproduced by this magnetomotive force is reversed in ydirection each time the reduced end 79 of the armature passes its central position, thereby inducing a current in the coil 27, correlated to the 4movement yof the armature G2 or the'needle 'T7/.carried thereby. This current may then be `amplified and converted into sound by any'suit'able means; i

A feature of the present invention is the -adjustable air gaps betweenth'e pairs of.l pole tipsV whereby to vary the reluctance of the magnetic circuits for magnets having variable or different magneto-motive forces, and for ampliers or phonographs having different characteristics.

While I have illustrated and described a specic embodiment of my invention, many modications may be made without departingV from the spirit of the invention, and `I do not wish to f be limited to the precise details set forth but f desireto -avail myself iof all changes within the scopeofgthe appendedclaims l Y Y. VLHavingjthus'fdescribed my invention, what I claimv-is/,new and desire tosecure by Letters Patent of the vUnited Statesis: Y I

1. YAA phonograph pickup comprising a magnet p having adjustably spacedl pole piecesprovided with corresponding slots extendinglongitudinally of said pole pieces, a coil carried by said .pole pieces, a movable armature passing through rsaid coil and between said pole pieces,rand a mount-` ing means for said armature carried in said corresponding slots.

. 2. A phonograph pickup comprising a magnet having Vadjacently disposed pole pieces pro-f ided with corresponding slotsat opposite sides of said pole pieces, a coil carried by said polev pieces, non-magnetic members slidably arranged in said slots and bridging between said pole ,v

pieces, and a `movable armature betweenv said pole Vpieces pivotally engaging said members at one side of said coil, and having a portion extending through said coil whereby to provide unequal variations in the magnetic reluctance between said armature and said pole pieces at op-` posite sides of said coil.

3. A phonograph pickup comprising a magnet,

a coil, a yoke bridging the ends of the magnet and surrounding the coil, said yoke including a pair of adjustable pole pieces having a plurality of aligned slots, and a plurality of non-magnetic` members engaging in said slots and holding the ends of said pole pieces in spaced relation, and a vibratory armature pivotally mounted on the non-magnetic members inwardly ofthe surface ofthe pole piecesVV on one side of said coil' and extending into the gap between the pole pieces on the other side'of said coilwhereby to induce a currentin said coil.

responding sidesa'pair of U-shaped magnetic members having aligned slots carrying said non-y magnetic members, said magnetic members beingv held in` adjustable spaced relation thereby and extending from centrally of the coil over Ythe lateral sides of said coil to centrally of the other side -of said coil, and providing adjustable gaps between the ends of said magnetic members, and an'A armature having av knife edge support car'- U riedfin the aligned grooves of said non-magnetic membersbetween said gaps, said armature-extending through said coil andvhaving its ends reciprocable in said gaps.

6. A phonographpickup comprising' a 'coiL-aV pair of pole pieces ateach end of said coil having gaps therebetween, a magnet associated with said polepieces, an armature extending through the gaps between the pole pieces and having a plurality of knife edges a plurality Vof channel members having grooves therein carrying said armature and said pole pieces, the pivot point of said armature being between the pairs of. pole pieces at-the end of said-coil, said pole pieces lbeing adjustable with respect to said'channel members to adjust the gap between said pole pieces, and means for moving the` armature about its pivot to generatefa current in said coil. f

'7;v A- phonograph pickup comprising` a magnet and a unitary generating assembly bridging between the poles of said magnet and including a eoiLcOmplementary bifurcated pole pieces adjustably assembled about said coil and a dampened vibratory member having a pivotal mount-

Images