US1779247A

US1779247A - Phonograph pick-up

Info

Publication number: US1779247A
Application number: US359203A
Authority: US
Inventors: Oliver B Parker
Original assignee: PACENT ELECTRIC Co Inc
Current assignee: PACENT ELECTRIC Co Inc; PACENT ELECTRIC COMPANY Inc
Priority date: 1929-04-30
Filing date: 1929-04-30
Publication date: 1930-10-21
Anticipated expiration: 1947-10-21

Description

Oct. 21, 1930. PARKER 1,779,247

PHONOGRAPH PI CKUP Filed April 50, 1929 ll QB;

INVEN A r 2m AT ORNEY Patented 21, I

UNITED STATES PATENT; OFFICE OLIVER B. P OI mzw YORK, N. Y., ASSIGNOB 1'0 PAOEN'I. ELECTRIC comm,

1170., ].NEW- YORK, ll. Y., A CORPORATION 0! NEW YORK.

moxoemn rIcx-ur Application mama so,

This invention-relates to the construction of pickups for electric phonograph reproduction.

Special objects of the invention are to provide a simple, practical, inexpensive device of the character mentioned, which can be readily assembled and adjusted for proper operation, which will be particularlyefiicient in its operation and which will be sensitive and [o powerful in its action and free of chatter and surface noises.

The various novel features of construction, combinations and relations of parts by which the foregoing and other desirable objects are 5 attained will be clear from the followin specifications. 7 v p The drawing accompanying and forming part of the specification illustrates certain practical commercial embodiments of the in- 0 vention, but the structure may be modified as regards the present disclosure without departure from the true spirit and broad scope of the invention.

Fig. 1 is a broken vertical-sectional view 5 of one form of the invention; Fig. 2 is a vertical sectional view at right angles to that of Fig. 1, as on line 2-2 of Fig. 1; Fig. 3 is a bottom plan view of the combined pole piece, coil and-armature unit as detached from the magnet; Fig. 4 is a top plan view with the casing appearing in section as on substantially the plane of line 4-4 of Fig. 1; Figs. 5 and 6 are broken part sectional detail views of the armature and pole construction with i the means for adjustably centering and cushioning the armature between the pole tips; Fig. 7 is a combined end and large view of a modified form of the armature cushioning means. I

The pickup disclosed is of the electromag netic type, embodying a magnet 8 carrying opposed U-shaped or C-

shaped pole pieces

9 and 10 with which cooperates an armature 11 vibrated by the record engaging needle 12, said armature being surrounded by the coil 13.

Pole pieces, armature and coil form together a single unit as indicated in Fig.. 3, which can be made up with the parts in properly associated relation and then be mounted 1989. Serial 1T0. 858,208. 7

'upon the arms of the magnet. To enable this result, the pole pieces are shown as secured together at the top by a fiat ring 14 of nonmagnetic material fastened to the upper arms of the pole pieces by screw studs 15 and nuts 16 and at the bottom by a thin resilient strip 17 of bakelite or the like fastened to the lower arms of the pole pieces by screws 18. These connections at opposite sides of the pole pieces hold the latter definitely and positlvely spaced, ready for'attachment to the ma net. The lower pole spacing member 17 is utilized in the present disclosure'as a resilient support for the armature, which latter is indicated in the form of a magnetic stud riveted at its lower end at 19.to the center of the bakelite strip in position with the upper flattened end or blade 20 of the armature dis- I .posed between the upper tapered tips 21 of the pole pieces. The armature stud is indicated as hollow in its lower portion to receive the needle and also to reduce its inertia and as having a seat above the bakelite strip for the needle clamping screw 22. The coil is indicated as ositioned in the hollows of the opposed U- aped pole pieces and as positively held by spring armed clamps 23 out of eneral U- hape secured on the upper ends 0 the screws 15 by the nuts 24 and having their down-turned ends engaging the rim of the coil at 25 at four substantially equi-distant points, so as to definitely locate and hold the coil Where it belongs, secure from shifting or rattling.

In addition to formin a resilient support, the bakelite mount intro uces a certain desirable damping effect on the armature. To eliminate any possibility of the armature striking the pole tips and to provide for definite adjustment and centering of the armature in the magnetic gap, two small levers 26. are shown pivotally and adjustably held on the mounting ring- 14 by screws 27 beneath a cross-clamppiece 28, said levers having arms 29 at their inner end extending down to opposite sides of the armature blade, Figs. 5 and 6. If sufliciently resilient, these arms may directly engage the armature, but they are shown as exerting control over the armature through the interposed elastic pads or blocks i pressed against the opposite faces of the armature blade. As their, purpose is primarily a centering function, the arms 29 and ads may be relatively narrow as indicated in Figs. 5 and 6 and the same may be located n free space in notches 31 provided in the ends of the pole pieces.

Because of the control afforded by the poduced to a minimum, the armature being adjusted to an intermediate central position between the pole tips by setting the levers to press the armature one way or the other to establish it in a centralized position. The cross-plate 28 exerts a clamping effect on both levers and may be utilized to temporarily retain the levers in adjusted relation before the screws 27 are tightened finally. This plate also prevents the levers from turning under the rotational force of the screws as the screws are being set up tight. By means of these levers, the armature may be shifted in the gap one way or the other and the cushioning or damping effect may be Varied by setting up the levers to exert more or less pressure against the sides of the armature. These various adjustments and the assembly of the parts can all be completed before attachment to themagnet. Thus, the pole pieces may be secured together at top and bottom in their properly spaced relation with the coil held in position therebetween and the levers set to position and hold the armature in its proper relation, all as a single complete finished unit, which unit may then be attached as such to the magnet. In the construction illustrated, this attachment is effected by screws 32 extending from the back through clear passages 33 in the arms of the magnet into screw seats 34 formed in the pole pieces which are flatly engaged over the outer face of the magnet. These same screws are shown utilized to fasten the case of the device together by being extended through the back wall 35 of the case 36 and through the upturned flange 37 of the removable bottom section 38 of the case, said flange being slotted up the back as indicated at 39 to enable this bottom section to be slipped into and out of position. A sheet of insulating material 40 is shown interposed between the back of the magnet and the flan e 37 of the bottom piece, this insulation eing pierced for the passage of the screws and carrying the terminals 41 for the coil. This sheet of insulation is shown as of substantially the same thickness as the flan ge 37 and is indicated as doubled back upon itself at the top at 42 in Fig. 1 to provide an extra thickness at the top equivalent to the thickness provided by the flange 37 at the bottom, so that in tightening the screws 32, the magnet structure will be pulled straight back against the back of the case. The body of the case is indicated as a single piece of sheet metal pressed into a cup-shaped form and arranged in inverted relation, the bottom piece 38 being shown as forced up into the open end of the cup-shaped shell and held by its flange, being gripped between the back of the insulatingbase and the back wall of the case. For supporting the -case, the bracket arm 43 is shown in the form of a casting riveted to the nel form, to carry the conducting cord 45 t0 the terminals 41 of the coil.

As shown in Fig. 4, the positioning levers 26 are pivoted intermediate their ends on the screws 27 so that the outer ends of these levers may be used as handles for adjusting the levers to the desired relations. These adjustments may be made before the coil unit is mounted on the magnet or after the so-called coil unit has been applied to the magnet as in Fig. 4. The pressure of the positioning levers against the armature may be as light, or as heavy as desired, and this pressure, even though light, is ordinarily sufficient to hold the rubber or other resilient pads in position against the armature blade, said pads having a tendency to bulge or spread over the upper corner edges of the armature blade as indicated in Fig. 5. If desired, however, the pads may be positively affixed to the levers or to the armature by the use of cement or other securing means. In the embodiment illustrated in Fig. 7, the pads are incorporated in a single short piece of rubber 3O squeezed into a slot 46 in the upper edge of the armature blade, so as to bloom out the ends of the same into pads engaged by the arms 29 of the levers.

To allow full freedom of action of the armature, the bakelite-like supporting strip is shown as having portions removed at 47 at opposite sides of the intermediate portion, Fig. 3, leaving only a transverse bridge portion 48 carrying the armature, which bridge portion is further indicated as narrowed at 49 on opposite sides of the armature rivet 19', so that the same can flex freely under the rocking action of the armature. The pole pieces are indicated in Figs. 2 and 3 as cut ack at 50, behind the cut-outs 47 and the bridge portion 48 of the bakelite support, so as to not interfere in any way with the flexure of the bakelite.

The device constructed as disclosed, is particularly small and compact, and at the same time the electrical efliciency is high. The pole pieces rest fiat against the front face of the magnet, attaining a maximum area of contact, without adding to the length of the magnet structure. The flat resilient mounting plate forthe armature does not add appreciably to the length of, the magnet structure and it provides a support for the armature which while solid enough to hold the armature properly located between the pole tips, is sufficiently resilient in the plane of rocking movement of the armature to pro- I back of the case at 44 and of hollow or chan- I sitioning arms, the magnetic gap may be re- 7 vide the desired sensitivity and maximum response. The coil is firmly and positively located in the open spaces of the polepicces and the devices for centering the armature and providing the desired tensionon the same are located above the pole pieces, so as not to increase the overall dimensions of the device. The ring and the armature mounting strip form spacers and clamp devices for definitely locating the pole pieces in cooperating relation, irrespective and independently of the means for finally securing the pole pieces to the magnet.

The pole pieces usually are of soft magnetic iron, so the screw seats 34 may be readily formed therein. The holes 33 in the magnet arms may be punched or otherwise formed before the magnet is hardened and preferably are over-size, so that the screws will pass freely therethrough into the seats provided in the pole pieces. This construction, it will be seen does away with any need for clamps to secure the pole pieces to the magnet, the two screws 32 serving to firmly and positively fix the pole pieces in fiat engagement .on the face -of the magnet.

Because of the character of the metal, the seats for the screw studs 15 and the seats for the screws 18 may be readily formed in the upper and lower arms of the generally C-shaped pole pieces. Only the front of the magnet and the back of the pole pieces need be faced as these are the only contacting parts and as these meeting faces are broad and flat, good magnetic joints are assured.

Both the coil and the armature positioning'arms or levers 23 and- 26 may be of sheet metal and may be sufficiently resilient to exert a spring tensioning efii'ect. They also may be bendable so that in case of necessity. they may be deformed one way or the other to exert a proper positioning and holding effect.

By fixing the resilient pads, as by cement or the employment of mechanical positioning means, as in Fig. 7, creeping of the rubber is prevented and hence the possibility of an unintentional change in adjustment in this cause is overcome. he coil may be fixed in its adjusted position in the pole pieces by securing means such as the .screws shown at 55 in Figs. 2 and 3 extending up through the lower ends of the pole pieces into clamping engagement with the underside of the coil spool.

In place of or in addition to securing the armature to the resilient bakelite support by riveting, the armature may be fastened on this support by a bakelite cement or the like.

What is claimed is:

1. Apparatus of the character disclosed, COmfPIISIIIf a magnet having spaced arms per orate through from front to back for the-free passage of securing screws, pole pieces faced to closely fit over the front face of said magnet and having screw seats in line with the screw passages in the magnet, securing screws extending freely through said passages from the back of the magnet and engaged in the screw seats in the pole pieces to thereby bind said pole pieces in close fitting supported engagement on the face of the magnet, said pole pieces having other screw seat-s, a bridge piece for rigidly spacing said pole pieces, screws engaged with said other screw seats and fastening said other bridge piece and pole pieces together as a unit independently of the screws fastening the pole pieces to the magnet arms, an armature element supported in cooperative relation to said pole pieces and a coil operatively associated with said armature.

2. In apparatus of the character disclosed, a magnet having spaced arms perforated for free passage of securing screws, pole pieces faced to fit the front face of the'magnet arms and having screw seats'therein in line with the perforations in the magnet arms, said pole pieces having screw seats in the top and bottom sides of the same, screws engaged in said top and bottom screw seats, a rigid spacing member for the pole pieces held by the screws at one side of the pole pieces, an armature mount held by the screws at the other side of said pole pieces and securing screws extending freely through the magclosed, a magnet having spaced arms perforated for free passage of securing screws, pole pieces engaged over the face of said magnet arms and having screw seats in line with said screw passages, securing screws extending from the back of the magnet through said passagesin the screw seats into the pole pieces, said pole pieces having screw seats in the lower sides of the same, a strip of resilient material, screws fastening said strip to the pole pieces and engaged in the screw seats in the lower sides of said pole pieces and an armature member mounted on said resilient strip and cooperatively associated with the pole pieces.

4. In apparatus of the character disclosed, a magnet having substantially C-shaped pole pieces, a coil disposed in the hollows of said substantially C-shaped pole pieces, .an arm overstanding said coil and having angularly turned ends embracing the edge of the coil to definitely position the latter in the pole pieces and an armature element .associated with the pole pieces.

5. In apparatus of the character disclosed, a magnet having substantially C-shaped pole pieces, a coil disposed in the hollows of said substantially C-shaped pole pieces, arms overstanding said 0011 and having angularly turned ends embracing the edge portion of the coil to definitely position the latter in the pole pieces and an armature mounted in cooperative relation to the pole pieces and coil.

6. In apparatus of the character disclosed, a magnet having substantially C-shaped pole pieces, a coil disposed .in the hollows of said substantially C-shaped pole pieces and positioning arms for said coil having angularly turned bendable port-ions engaged with the rim of the coil.

7. In apparatus of the character disclosed, a magnet having pole pieces, a connecting member secured to said pole pieces, a coil associated with said pole pieces, positioning means for said coil arranged on said connecting member, an armature associated with said pole pieces and positioning means for said argiature also arranged on the connecting mem- 8. In apparatus of the character disclosed, a magnet having pole pieces, a spacing ring mounted on said pole pieces, a coil associated with the pole pieces, coil positioning arms above the mounting ring, armature positioning means on the mounting ring and an armature associated with the pole pieces and posi-' tioned by said armature positioning means.

9. In combination with a magnet having spaced poles, an armature supported in 0- operative relation to said poles, levers pivoted to one side of said armature mounted for swinging movement, the ends of said levers being positioned for travel in such pivotal movement toward and away fromopposite sides of said armature and clamp means for securing said levers in variably adjusted relations.

10. In combination with a magnet having spaced poles, an armature supported in cooperat1ve rel ation to said poles, levers mounted for swinging movement toward and away I from 0 posite sides of said armature, clamp means or securing said levers in variably adjusted relations, including screws on which the levers are pivotally mountedand a crossclamping plate held by said screws against the levers.

11. In combination with a magnet having pole pieces, an armature supported in cooperative relation to said pole pieces and an armature positioning lever pivoted intermediate its ends on a center positioned to one side of the armature, the inner endof said lever having a resilient connection with the armature and the outerend of said lever projecting away from the armaturev for enabling adjustment of the lever at a'point to one side of and'removed from the armature and means for securing'the lever in variously adjusted relations.-

12. In combination, a magnethaving pole pieces, a strip of resilient insulating material porting section between the slots in position to cooperate with the pole pieces.

13. As a new article of manufacture, an armature mount for phonograph pickups, comprising a flat resilient strip of insulating material slotted transversely to leave a resilient bridging portion having narrowed neck portions at opposite sides of the intermediate section of the same. i

14. As a new article of manufacture, an armature construction for electric phonograph pickups, comprising a strip of phenol condensation product and an armature stud fixedly secured to the intermediate portion of said strip, projecting from one face of the same and having a stylus socket exposed on the opposite face of the strip. v

15. As a new article of manufacture, a strip of phenol condensation product, transversely slot-ted .to opposite sides of an intermediate portion and an armature element rigidly secured in projecting relation on said intermediate portion.

16. In apparatus of the character disclosed,

v a magnet having pole pieces, a spacing ring