US1817021A - Electric pick-up - Google Patents

Description

Aug. 4, 1931. w. H. sci-"MPF 1,817,021

ELECTRIC PICK-UP Filed Sept. 20. 1929 ENTOR ATTORN EY Patented Aug. 4, 1931 PATENTl OFFICE. f

XVALTER H. SGI-"IIM-PF; OF TLEDO, OHIO* ELECTRIC PICKvUP Application filed' September 20, 1929.- SerialA No. 393,920.

The present invent-ion relates to` electric pickups for use with phonograph records and the like, adapted to generate electric currents in accordance with the vibratory a movements cfa stylus traveling inthe record groove. f

` The present invention contemplatesv an electric pickup providedl with -a' current generatin Y coil stationar ma0net s stem andi lo vibratory stylus and"operativeparts so ar-- rangedl that the form-fof the current wave generated therebyy will reproduce with-ex cellent fidelity, the form of the record groove by which the stylus isoperated.

yThe present invention contemplatesfan im;- proved electric pickup havingl excellent tracking qualities and desiredA fidel-ity over a-widerange of frequencies s0 that the picky up willl reproduce not onlythe lownotes but ing' according to the movement of the-stylus,

whereby all the flux variations in the core l take place atcoinparatively low intensity, 0 thereby avoiding the effects of, saturationI present where the magnet systememploysj a more or lessy saturated core The pickup is accordingly so designed that a yvibiratory armature in the ieldi of the magth'fnormally balanced flux relation in the core to induce flux-therein and thereby^generate undu'latory' currents.

The present invention also contemplates the design ofen electric pickup inlsuch ai manner-thatthe partsfniay be readily assem@ bled'andv adjustedfand yetbe held in postV tionby rugged parts so that therer is little f likelihood of thede'vic'eA requiring attention 5 once itis adjusted. j I

The present v'invention also` contemplates an electric piclrup` wherein adjustable resilientstops offering no appreciable resistance to thevbration of the bar hold the stylus in position. so' as' prevent-itis net and outside thefcoilis caused to-,distiirb striking the pole tips or being attracted too close to one ofthem.

The presentk application relates to Acertainimpi-'ovements over-the forms shown in my prior application 153,5965v filed December 9; i926. l A

rlhe accompanying drawings show, for` purposesof'illustrating the presentl invention, one embodiment in which the invention may take form, together -with several modi# iications of certain parts, it l'ieing'l under,z stoodthat the drawings are illustrative ofr the invention rat-hier than limiting the'saine;

In the drawings:

Figure l is a front view of'thepick-up, withy the cover removed; y y

Figure 2 is a central section on the line 2 2 of Figure l;

Figure 3 is an enlarged view taken in the same direction as Figure l, but showing a; slight modification;

' Figure 4l is a fragmentary section on: thel line 4-4 of Figure 2 looking-in the direc, tion of the arrow;

Figure 5y is a section onthe line v5&5 of' Figure l looking in the directionA of the arrow;

Figure 6v is a side elevational Viewv ofthe pickup showingit in position overa record;

Figures 7 andA 7a are enlarged front and' sectional views showing a modified arrangement of vibratory stylus bar and pole pieces;

Figure Sis a` fragmentary view illustratiing a modified form of core;

Figure 9 is a view similar to Figure 8'-y showing a still further modified form of'core and vibratory armature; and v Figure lOis a view similar to Figure 3*Y showing a modiiied forinof resilient'stop for thev vibratory stylus bar.

The electric pickup is mounted on aA swingJ ingreproducer support 10 ot kmore onlessr` conventional shape so that the reproducen canx move back l"and iort'hfovery the surfaceof the' phonograph or other' form of disc record. It'A Wilhoflcourse, be understood that the piekupmay be mounted on anysuit-y able form of support to have it coo( rate y with the record grooves of disc orcy ingiere' recoins or other' types caf-records hearing impressions adapted to actuate a reproducer stylus.

As more clearly shown in Figure 2, the supporting arm lO is secured to a supporting plate 11, and this plate carries a ixed base or support 12 on which are mounted the magnet, the core, the coil and the vibratory stylus bar. as shown" in detail in Figures 1 to 'inclusive. v The stylus is indicated at 13. It is clamped in place in a stylus bar 14 by a clamping screw 15. The stylus bar has laterally extending bearing members or pintles indicated at 16 which are provided with ball receivarmature members 22 and 230i soft iron.

The stylus bar is made of a non-magnetic material, preferably of light weight material such as an aluminum alloy. rThe stylus bar is here shown as being provided with resilient sponge rubber pads 24 covered with thin metal plates l25. Adjustingscrews 2G are threaded through the side walls 27 of the support or' base 12 and are adjusted against these resilient pads so as to hold the stylus bar in a neutral position and prevent chat tering. The adjusting screws 26 may be placed above the pivot, as shown in Fig. 1, or below the pivot, as shown in Fig. 3. They are locked in place by lock nuts 28.

The magnet for the lpickup is indicated at 30 and is here shown in the form of a horseshoe magnethaving poles located at31 and 32. Pole pieces or tips 33 and 34 are secured'on the support 12 by screws indicated at 35. These pole tips are spaced apart to provide a gap slightly greater than the width of the movable armature and are so shaped that the larmature projects above the pole tips as will be clear from Figures 1 and 3. -AlThe magnet is clamped in place by'a bridging strap 36, secured to the support 12- by bolts l37 lthreaded into a bridge38 in the supporting base 12. j Y

The upper end of the supporting base 12 isv'providcd vwith a forward extension orv is clamped vin place by a screw 43 threaded into-the Jforward extension 39. The core 41 carries; a coil 44, this coil being preferably" aprev\`zoundV coil shaped toiit between the bridging members 38 and 39.7Y The coil iS slipped in place between the bridging members and the core passed through the opening in the coil to secure it in place and is then secured in adjusted position by the screw 43. The coil has leads 45, 46 adapted to be secur- L ed to binding posts 47 carried in the upper end of the support 12. These binding posts are'connected to wires 48 passing out through the reproducer support 10.

The lower end or tip of the core 41 is notched as indicated yat 50. The width of this notch is substantially the same as the spacing between the pole tips 33 and 34. The armature members22 and 23 extend into this notch but do not Contact with the tip of the core. The tip of this core is spaced a substantial distance from the pole tips 33 and 34 so that Va negligible amount of magnetic flux will Vbe induced in the core, most of the flux passing directly across the air gap and across the armature.

In assembling the device, the stylus bar and associated parts are secured in place, the pole tips being mounted on the base. 'Ihe coil may vthen be inserted in place and the core secured in position after which the magnet may be slid into place by being passed down alongside the support 12 and secured by the bridging strap 36, The device is closed and covered by a protecting cover plate 52 which may be held in place by nuts 53 threaded onto the endsv of the studs 37.

In the form of construction shown in Figure 7 and 7a, the vibratory stylus bar is designed to be much shorter than the form shown in Figure 1. Here the needle or stylus 71 is'secured in place lby a clamping screw72 above the axisA 73 about which the stylus bar vibrates. The stylus bar is provided with armature members 74 carried between pole pieces 75 and 7 6 similar to the pole pieces 33 and 34. The armature vibrates adjacent to core 77 similar to the core (41.. In order to concentrate the magnetic field in the gap, the lower edges of the pole tips 75 and 76 arevrounded or beveled as indicated. The adjustable stop screws 78 are similar to the clamp screws 26 but in this figure the resilient connection is in the form of springs 79 which surround pins 79 carried by the stylus bar and which enter recesses 79 in thevsupport 12. v

The stylus bar is mounted on ball bearings as indicated, and in both these forms of construction, the pivot is located approximately midway between the needle point and the armature so as to obtain a 1 to 1 relation. y

In the form of construction shown in Figure 8,' the parts may be the same as shown in Figures 1 toI3 except that as here shown the core 81 is .cut awayv to provide a long gap 82 thereby making a somewhatv longer path for magnetic flux escaping and leaking from the pole tips into thev core.

CII

' free kfrom restraint.

armature.

' In the form of construction shown in Figure9, the armature member 91 1s indicated as being in the formv of a single piece of soft iron suitably secured to the vibratory stylus bar. rIhis single vpiece of magnetic material beingcarried midwayy between the pole't-ips receives induced magnetism of both poles 4and has a neutral'zone through the middle o-f its mass. It acts as a two piece Here the pole tips are brought much closer together and the core 92 has a much narrower gap 93. n

vInthe form of construction indicated in Figure l0, the movable stylus bar is of the type shown in Figure l and the same reference characters are employed. Instead, however, of having the adjusting screws bear directly on the plates 25 surrounding the sponge rubber pads, additional resilient stops are provided in the form of cups 95 slidably carried in drillings 96 and urged toward the stylus bar by springs 97 held in place by screws` 98.

In the various forms of construction herein shown, the stylus bar is adjusted to normally lie-substantially centrally between the pole' tips and hence the iron armature members carried thereby are substantially equally magnetized and of opposite polarity. In theA case of the one piece armature of Figure 9,I the opposite halvesofthis piece act as separate and distinct magnets of equal intensity and opposite polarity. When the armature is in the neutral position, a

vnegligible amount of iuX is created lengthwise of the core, but as soon as it is moved in either direction, the flux in the core is redistributed thereby generating a current in the coil which may be amplified and employed in the usual manner.

So far as the ear is able to detect, the devices made with he magnetic arrangement shown in Figures l, 8 and 9 lall operate in substantially the same manner and give excellent reproductions of phonograph records.V So far as the ear is concerned there appears to be no difference in the quality of the music or speech produced by either of these arrangements.

The arrangement provided in Figure 7, however, will give better reproductions of highery pitched notes owing to the much smallermass of moving parts.

In all these forms of construction, it will be noted that'the armature is substantially It is able to move without being impededk by stiff springs. The stop means provided offer practically no resistance to the vibration' of the armature.A As the iron inthe coil is operating at exceedingly low density, ux variation willV be far more faithful than. in forms of construction in which thecore is at all times operating under comparatively high .thin density..

The placing of the coil and core between the sides of the magnet is a very convenient and compact arrangement and economizes spaces and produces a nice balance over the needle. The position of the magnet relative to the core and coil seems, however, to have little effect on the quality of the reproduction. If one pole is held adjacent a pole piece, weaker currents of excellent quality but less value are produced.

It is obvious that the invention may be embodied in many forms and constructions, and I wish it to be understood that the particular forms shown are but a few of many forms. Various modifications and changes being possible, I do not limit myself in any way with respect thereto.

That is claimed is:

l. An electric pickup for phonograph records and the like comprising, a stationary magnet system having fiXed, spaced apart poles, a stylus operated vibratory member havin()i magnetizable material carried between the poles but out of contact therewith, a coil, and a magnet-izable core in the coil, the core and coil being housed within the magnet of the magnet system with the tip of the core adjacent the vibratory magnetizable material and out of contact therewith.

2. An electric pickup for phonograph records and the like, comprising, a stationary magnet system including a horseshoe magnet and having fixed, spaced apart poles, a vibratory armature member having magnetizable material carried between the poles but out of contact therewith and rigidly connected to a stylus to be actuated thereby between the poles, a coil, and a magnetizable core in the coil, the tip of the core being adjacent the vibratory magnetizable material and out of contact therewith, the core being disposed relative to the magnet system such that it normally receives substantially no iux therefrom.

3. An electrical pickup for phonograph records and the like, comprising a stationary magnet system having fixed, spaced apart poles, a stylus fastened to a stylus carrier, a support on which the stylus carrier is pivotally mounted, the stylus carrier being provided with a magnetizable armature disposed between the poles and adapted to be vibrated back and forth in the air gap, a magnetizable core adjacent the armature and adapted to receive a varying flux according to the position of the armature, and

a Vcurrent generating coil wound about the' core.

4;. An electrical pickup for phonograph records and the like, comprising a stationary magnet system having fixed, spaced apart poles, a stylus fastened to a stylus carrier, a support on which the stylus carrier is pivotally mounted, the stylus carrier being provided with a magnetizable armature disposed between the poles and adapted to be vibrated back and forth in the air gap, a magnetizable core adjacent the armature and adapted to receive a varying iuX according to the position of the armature, and

a current generating coil wound about the core, the core and coil'being housed within the magnet system parts with the core lin the neutral zone thereof.

5. An electrical pickup for phonograph records and the like, comprising a stationary magnet system having pole tips spaced apart to provide a narrow air gap, a stationary core having one end adjacent the pole tips, an armature providedv with magnetizable material disposed in the air gap and being close to the poles and the tip of the core, a pivotal mounting for the armatureY to permit it to move back and forth in the air gap, a stylus bar rigidly connected to the armature and to a stylus, the pivotal mounting being substantially equidist'ant -from the armature and stylus, and a coil about the core in whichl currents are generated by vibrations imparted to the stylus.

6. An electrical pickup for phonograph records and the like, comprising a current generating coil, a core for the coil, and a stylus bar carrying a vibratory armature movable relative to the end of the core and relative to fixed magnet poles to vary the flux through the core, the core normally receiving substantially no magnetic iiuX from the magnet poles, and a stylus for vibrating the armature.y .Y Y

7. An electrical pickup for phonograph records and the like, comprising a current generating coil wound about a magnetizable core, a magnetic system including a vibratory armature 'operable by and directly connected with a stylus to generate currents in the coil, means for pivotally supporting the stylus and armature so that they aremovable in either' direction from a neutral point with equal facility, and resilient means to hold the armature out of contact with the stationary parts of the magnet system.

A8. An electrical pickup for phonograph records and the like, comprising a vcurrent generating coil wound about a core, a magnetic system including a vibratory armature operable by and directly connected with a stylus to generate currents in the coil, means l for pivotally supporting the stylus and armature so that they are movable in either direction from a neutral point with equal facility, and resilient means to hold the armature out of contact with the stationary parts of the magnet system, the core and coil being mounted inside the magnet of the magnet system with the core substantiallyA in the neutral zone of the same.

9. An electrical pickup for phonograph records and the like, comprising a support,

a permanent magnet carried thereby', thek magnet having spaced pole tips adapted to accommodate an armature, a 'coil mounted between the side members of the magnet and having a corecadjacent the pole tips and in the neutral zone of the magnet, and a stylus operated vibratory armature operating in the gap kbetween the pole tips and in the gap between the pole tips and the core tip, and acting to vary the flux distribution in the core according to the position of the armature in the gap. V

10. An electrical pickup for phonograph records and the like, comprising a support, a permanent magnet carried thereby, the magnet having spaced pole tips adapted to accommodate an armature, a coil mounted between the side members of the magnet and havingV a core adjacent the pole tips and in the neutral zone of the magnet, and a stylus operated vibratory armature operating in the gap between the pole tips and in the gap between the pole tips and the core tip, and acting to vary the flux distributionv in the core according to the position of the armature in the gap, the gaps between the pole tips and core tip being greater than the gaps between the pole tips and the armature.

l1. An electrical rpickup for phonograph records and the like, comprising a stationary magnet, a current generating coil wound about a fixed core, the core and coil being mounted between the side members of the magnet, and a stylus operated vibratory armature in the magnet field and adjacent the core, the core normally receiving no flux from the magnet but receivingV varying flux according'to the position of the armature when operated by the stylus whereby currents are generated in the coil. f

12. An electrical pickup for phonograph records and the like, comprisingja support, a magnet carried thereby, pole pieces for the magnet separated to accommodate an armature, a stylus bar carrying a stylus at one end and an armature at the other end, the support having bearings for the stylus bar to carry the armature in the gap Vand permit it to move longitudinally of the gap,

a magnetizable core close to the armature and adapted to be magnetized according to the position of the armature, and a current generating coil about the core. y

-13. An electrical pickup for phonograph records and the like, Vcomprisinga support,

a magnet carried thereby, pole pieces for' the magnet separated to accommodate an armature, a stylus bar carrying a stylus at one end and an armature at'the other end, the support having bearings for the stylus bar to carry the armature in the gap and permit it to move longitudinally of the gap, a magnetizable core close to the armature and adapted to be magnetized according to the position of the armature, a current generating coil .about the core, and adjustable yieldable stops engageable with the stylus bar and acting to keep the armature out of contact with the magnet.

14. An electrical pickup for phonograph records and the like, comprising a support, a stylus bar pivoted therein, a stylus carried by one end oli the bar and an arma ture at the other end, a magnet carried by the support and having pole pieces close to the armature and on opposite sides thereof, a coil carried by the support, a stationary core in the coil, the tip of the 'core having a gap to receive the armature, and resilient stop means to hold the armature spaced from the core tip and pole tips whereby substantially no tlux is'induced lengthwise of the core.

l5, An electrical pickup for phonograph records and the like, comprising a support, a stylus bar pivoted therein, a stylus carried by one end of the bar and an armature at the other end, the stylus and armat'ure being substantially equidistant from the pivot point, a magnet carried by the support and having pole pieces close to the armature and on opposite sides thereof, a coil carried by the support, a stationary core in lthe coil, the tip of the core having a gap to receive the armature, and resilient stop means to hold the armature spaced from the core tip and pole tips whereby substantially no flux is induced lengthwise of the core.

16. An electrical pickup for phonograph records and the like, having a magnet with closely spaced pole tips, Va vibratory arma ture therebetween, a coil housed within the magnet and having a magnetizable core projecting therefrom with its tip adjacent the armature.

17 An electrical pickup for phonograph records and the like, comprising a support having a bearing at the lower end, a stylus bar pivoted in the bearing for vibration about one iixed axis, a stylus carried at one end of the bar and an armature at the other end, a magnet carried by the support and having pole tips close to the armature and on opposite sides thereof, the armature being movable in the air gap to Change the flux distribution between the pole tips and projecting beyond the pole tips, a stationary coil carried by the support, and a stationary core 'forthe coil, the end of the core being disposed adjacent the armature and substantially spaced from the pole tips, whereby substantially no flux is induced lengthwise of the core when the armature is in neutral position.

18. An electrical pickup for phonograph records and the like, comprising a support having a bearing at the lower end, a stylus bar pivoted in the bearing for vibration about one fixed axis, a stylus carried at one end of the bar'f'and an armature at the other end, a magnet carried by the support and having pole tips close to the armature and on opposite sides thereof, the lines of flux between the poles being in the direction of motion of the armature, J`he armature being movable in the air gap to vary its distance from the pole tips whereby one pole or the other predominates, the armature projecting i `beyond the pole tips, a stationary coil carried by the support, and a stationary core or the coil, the end ot the core being disposed adjacent the armature and substan tially spaced from the pole tips, whereby ture and on opposite sides thereof, the armature being movable inthe air gap to change the flux distribution between the poley tips and projecting beyond'the pole tips, a stationary coil carried by the support, anda stationary core for the coil, the end of the core being disposed adjacent vthe armature and substantially spaced from the pole tips,

whereby substantially no flux is induced lengthwise of the core when the armature is in neutral position, the coil and corebeing mounted between the sides of the horseshoe magnet. 'i

20. An electrical!pickup for phonograph records and the like, comprising a support having a bearing at the lower end, a stylus bar pivoted in the bearing for vibration about one fixed axis, a stylus carried at one end ofthe bar and an armature at the other end, a horseshoe magnet carried by the support and having pole tips close to the armature and on opposite sides thereof, the armature being movable'in the air gap to change the flux distribution between the pole tips and projecting beyond the pole tips, a stationary coil carried by the support, and a stationary core for the coil, the end of the core being disposed adjacent the armature and substantially spaced from the pole tips, whereby substantially no flux is induced lengthwise of the core when the armature is in neutral position, the coil and core being mounted between the sides of the horseshoe magnet, and with the axis of the coil substantially in line with the axis of the stylus bar.

2l. An electrical pickup for phonograph records and the like, comprising a support having a bearing at the lower end, a stylus iis bar pivoted inthe bearing for vibration about one fixed axis, a stylus carried' at one Vend of the bar and an armatureat the other end, a magnet carried by the support and having pole tips close to the armature and on opposite sides thereof, the armature being movable in the air gap to vary its distance from the pole tips and projecting beyond the pole tips, a stationary coil carried by the support, a stationarycore for the coil,

the end of the core being disposed adjacent thel armature and substantially spaced from the pole tips, whereby substantially no flux is induced lengthvviseof the core When the armature is in neutral position, and adjustable, yieldable stops cooperating with the stylus bar to prevent contact of the armature with the pole tips.

V22. An electrical pickup Jfor phonograph records and the like, comprising a support vhaving a bearing at the lower end, a stylus bar pivoted in the bearing for vibration about one iixed axis, a stylus carried at one end of the bar andan armature at the other end, a magnet carried by the support and having pole tips close to the armature and onopposite sides thereof, the armature beingmovable in the air gap to vary its distance from the pole tips and projecting beyond, the pole tips, a stationary coil carried by the support, a stationary core for the coil,

the end of the core being disposed adjacent` the armature and having a longitudinally extending armature receiving slot, the core being substantially spaced from the pole tips, whereby substantially no flux is induced lengthwise of the core When the armalture, is in neutral position. f

23.. An electrical pickup adapted for use Withlateralcutphonograph records and the like, comprising a support, a stylus bar pivoted therein to move back and forth under the Lcontrol of the record groove, an armature carried by the Vbar opposite the pivot and partalring of lateral motion of .sound character, a stationary core and current generating coil the axis of Which are approximately in line With the axis of the stylus bar, and aV magnet system having poles o n opposite sides of the armature.

a Y WA LTER H. SCHIMPF.

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