US2275404A - Phonograph drive - Google Patents

Description

|`=. D. BANNANG PHONOGRAPH DRIVE March 1o, 1942.

Filed Dec. 23, 1939 4 l N VE N TO l2., Fre/HM 50M/f7 AT T C KNEY vthan in the grooves adjacent the center of Patented Main/10,1942

2,275,404 t t PHONOGRAPH DRIVE.

Frederick D. Banning, Los Angeles, Calif., assignor, by mesne assignments, to Memovox, Inc.,

Beverly Hls, Calif., a corporationof Ohio Application December 23, 1939, Serial No. 310,853 t (ci. 74-393) 8 Claims.

This invention relates' to transmission mechanism adapted'to connectI a phonograph turntable with a source of power for rotating the table.

In records ot the so-called disc type, the sound track or groove carrying the record extends in a helical path from near the periphery A ducing or recordin head is moved over the record in a generally r dial direction to permit the stylus to follow or form the groove.l With a constant Aspeed of rotation for the record disc, the linear speed at which the record surface passes the needle or stylus is constantly changing,- being two to three or more time'sas great in the grooves adjacent the periphery of the record the record. l

The linear speed of the outer grooves may thus be much greater than is suitable vfor successful recording or reproduction, and in fact so great as to impose an undesirable load on the record material. On the other hand, the linear .speed of the grooves adjacent the center, may be lower than that suitable for the best results in recording and reproduction, and inl fact the nearness with which the recording may be carried to the center of the record is denitely limited by this reduction in surface velocity.

With certain types of record materials, it is quite essential to maintain the linear velocity of the record groove below certain limits; hence it has been proposedl to arrange the driving mechaof the record to near its center. and the reproso thatthe speed ofthe turntable will change progressively at a constant rate.

`It is a further object of this invention to provide such a mechanism having means for causing the stylus head to move across the record f at a desired rate.

It is still another object of this-invention to 'provide a mechanism embodying means for maintaining the stylus head in correct position at anyv times with respect to the instantaneous "ratio of the transmission; in other words, to ensure that the turntable will rotate at the proper speed with respect to the position of the stylus.

, In using a phonograph;- either for recording or reproduction purposes, it is frequently necessary to back-space or move the stylus head back from some point on'the record, possibly the termination of the recording, either for a. short distance as to hear the last few words or bars of'the' recording, or possibly the entire way to the beginning,` as in a repeater; 'or as in preparation `forl a succeeding record carrying member.

It is a further object of this invention to provide a mechanism giving a quick and convenient means for accomplishing such back spacing.

It may also sometimes-be desirable to advance the stylus head, while it isiifted oir the record,

nism for the turntable so that the latter revolves at a `constantly varying speed, dependent upon,

the position of the head carrying the stylus, so

that the record groove passes under the stylus at the same velocity, regardless of whether the head is near the periphery oi the record or near its center. v

Such an arrangement not only permits the use of record material which would otherwise not be useable, but also t gives greatly improved recordation and reproduction. Further in any case it permitsthe use of larger diameter records since the peripheral speed does'not reach prohibitive limits, and it likewise permits the carrying of the groove much nearer the record center. since the velocity is maintained at the proper ilgure', thus materially increasing the capacity of the record.

It is a principal object of this'invention to provide an improved form of transmission mecha'- nism for connecting a phonograph turntable to a source of power, operating at a' constant speed,

toward the end of the record carrying member at a more rapid' rate than normal, as when it is desired to skip a portion of the record or leave a blank space.

It is a still further vobject of this invention to provide a mechanism incorporating means for imparting such an advance to the head.

It is stilllanother object of this invention to provide means for readily controlling the back spacing and advance of the stylus.

It is a still further object of the invention to provide aback spacing arrangement with whichl it is possible to backl space for only a part ofa groove o n the record.

`'I'his invention possesses many other advantages/and has other objects which may be made more easily apparent from a considera-tion of one embodiment of the invention. For-this purpose there is shown a form in the drawing accom- 'panying and forming part of the present speci- In the drawing:

Figure 1 is a sectional view, largely diagrammatic, illustrating the transmission arranged to drive a turntable;

Fig. 2 is a detail section as seen on plane of Fig. 1;

Fig. 3 is an end view on an enlarged scale of one of the clutches used in the transmission;

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stylus head which may be either a reproducing' head or a recordinghead, or a combination head, is supported on suitable guides so as to move across the table 5 in a generally radial direction. Means are provided for so moving this head, as will presently appear.

Transmission mechanism 9 includes rollers II and I2 which are rotatably supported on frame 1, and have non-parallel or diverging axes. One

of these rollers, as I I, is tapered or conical, while the other roller I2 is shown as cylindrical. The

lower roller I2 is arranged to be driven by motor 8, through connections to be presently described; the upper or conical roller I I is arranged to drive the turntable 5. Operatively connecting roller II with roller I2 is a friction roller or idler I3. Means are provided for moving this roller and at the same time maintaining it in contact with rollers II and I2. Since one of these, II, has a progressively changing diameter,l the speed ratio between rolls II and I2 will be dependent upon the position of idler I3 between them, the speed ratio changing as the position of the idler changes. Thus the speed 'of the table 5 will vary as idler I3 is moved, and by providing suitable connections between the idler and the stylushead so that the head will move toward the outside of the record as the idler moves to decrease the speed of the turntable, and by suitable proportioning of the various parts, the rate at which the record groove passes the stylus can be maintained constant for all positions of the stylus.

With this general picture in mind, the details of the mechanism can be set forth. The. motor 8 is suitably supported with relation to frame 1 and is provided withpa worm 20 secured to its shaft 2|, worm 20 engaging a worm wheel 22 secured on shaft 23. Shaft 23 adjacent worm wheel 22 is rotatably supported in a downwardly extending arm 24 of frame 1, the other end of shaft 23 having slidably secured thereon, one` member 25 of a jaw clutch 26. Clutch memberv 25 has a hub 21 rotatably supported in a downwardly extending arm 28 of frame 1. Hub 21 in turn supports the right hand end of shaft 23. Roller I2 has the other member 29 of clutch 26 xed to its right hand end. Roller I2 is carried on shaft 23 and is freely rotatable thereon, unless coupled to the shaft by clutch 26.

Clutch member 25, slidably mounted on the en'd of shaft 23 is restrained vagainst rotation with respectthereto bya diametrically arranged pin 38. Pin 39 is Vsecured in shaft 23 and engages slots 3I formed at diametrically oppositev portions of hub 21. Apair of springs, one of which is shown at 32,' extend between pin 38 and member 25, and are effective to urge member-25 toward the left along the shaft and into engagement with clutch member 29 on roller I2. Thus,

roller I2 is normally in driving engagement with shaft 23 and motor 8.

As a convenient means of disengaging clutch 26, an electromagnet 33 is provided. When-magnet 33 is energized, clutch member 25 is attracted to the right, and out of engagement with the cooperating member 29. Thus, roller I 2V is no longer driven by shaft 23, but is free to rotate thereon.

Secured on shaft 23 adjacent worm gear 22 is a spur gear 35 meshing with a. larger spur gear 36, rotatably mounted on worm shaft 31. Gear 36 has one member 38 of a clutch 39 secured thereto. The other member of clutch 39 is slidably secured onv shaft 31 by means of a pin 4I engaging slots 42 'in member 40. Member 40 is thus in driving relation with shaft 31 and is urged intoy engagement with member 38 by hairpin springs 43. Thus, shaft 31 is normally in driving engagement with gear 36, and hence motor 8. An electromagnet M is provided to pull 'member 40 to the left when energized, thus disengaging this member and freeing the shaft 31 from driving engagement with gear 36 and permitting gear 36 to revolve freely on the shaft.

The arrangement of clutch 39 is similar in all respects to that of clutch 26, and is shown in` detail in Figs. 3 and 4.'v

Idler I3 is mounted on and threadedly engages the threaded portion46 of shaft 31, but is freely rotatable with respect thereto in response to force exerted by rollers II and I2. Idler I3 may conveniently include a hub 41 of metal or other suitable material with a friction facing 48 of leather, rubber or other suitablematerial engaging the rollers.

Roller II is secured on shaft 50 which is rotatably supported in arms 24 and 28 of frame 1 Oneend of shaft' 50 carries a skew gear 5I which meshes with a cooperating skew gear 52 carried by a short vertical shaft 53 rotatably supported in frame 1. Shaft 53 also carries a friction wheel 54 which engages an annular flange 55 on the underside of turntable 5. By this `means, roller II is in driving relation with turn- With clutches 26 and v35| each engaged and motor 8 operating to drive roller` I2 in the direction indicated by arrow 51, roller I I will be driven in the same direction by means of idler I3, the relative rates of rotation of the rollers II, I2 depending on the position of the idler I3. The rotation of idler I3 on the worm 46, will cause the f idler to travel axially along worm v46, the speed' and direction of the movement depending on the rate and direction of the rotation of the worm 46 with respect to idler I3 as wellas on the pitch and direction of the threads of the worm.

As shown, worm 46 has right hand threads and rotates at a less speed than idler I3, since the ratio between gears 35 and 36 is less than the ratiol between roller I2and idler I3. Thus idler I3 and shaft 46 rotate in the same direction but the idler rotates faster than the shaft. Hence, theA idler structure I3 moves -slowly to the left as a result of the Vaction of the threads. This movement results in the idler contacting a continuously larger portion of roller II resulting in increased speed reduction and a decrease in the speedof turntable 5. v

To correspond with this decreasing turntable speed, the stylus head should of course be moving toward the periphery' of the table.

Such

movement can be conveniently supplied to the stylus head 100 by connecting it with an arm 60 (Fig. 2) carryinga fork 6| adapted to be confined between flanges 62, 63 formed on hub 41 of the idler structure I3. y

With the mechanism operating as shown and described, the stylus head travels toward the periphery of the record or to the -left (Fig. 1), and the speed of the table 5 decreases. However, roller II can be driven inthe opposite direction equally as well, in which casethe stylus head |00 would travell to the right, or toward the center of the record, and the speed ofthe table would increase.

' If now clutch 26 is disengaged, as by energizing magnet 33, rollerv I2 will not be 'drivenby the shaft 23'and will be restrained -by a small friction'brake 65 which may be a piece of felt secured to arm 24 of frame 1 and continuously engages the surface of the roller. The roller II will not entirely stop, however, as will presently appear. Worm 46 will lcontinue to rotate, and

since idler I3 is no longer' being driven, it will now be urged to the right, orina back-spacing direction, by the threads of Worm 46. If roller |'2 was. held against rotation it would be neces# 85 adapted to engage contact v13, while memberv 80 carries contacts 86 and 81 adapted respectively to engage contacts 12 and 14. A compression sary for the surface of idler I3 to` slide in an axial direction along the surfaces of rollers I2 and II. On the other hand ifroller I2 was free to rotate, the idler I3 would probably be carried around by worm 46 without relative rotation between them, and the idler I3 would not move along the Worm at all.

By placing the restraint 65 on roller I2, idler I3 is prevented from turning with the worm 46, thus ensuring that the idler will be moved to the right. At the same time, since roller I2 is capable of restrained rotation, idler I3 is not compelled to slide on its surface, but turns slowly due to the friction between the idler I3 andthe worm 46. This turning imparts a corresponding slow rotation to rollers II and I2, so that idler I3 describes a spiral on the surface of the rollers. It will be plain that the back spacing movement of the idler structure I3 and connected parts is much more rapid than its movement in a forward direction. Due to the continued rotation of the turntable, it is possible to back space the stylus for less than one groove or complete -revolution oi' the table.

If it is desired to move the stylus head rapidly in the direction of advance, clutch 39 is disengaged, clutch 26 remaining in engagement. This causes worm 46 to stop rotating. Ihe idler I3 due to its rotation imparted by roller I I', will then move rapidly to the left along the worm. Here again the turntable will continue to rotate, making possible an advance of a fraction of a groove.

The operation of the phonograph maybe conveniently controlled by a push button type of switch 10, diagrammatically shown vin Fig. 1. 'I'his switch may comprise a block of insulating material 1I supporting three stationary contacts 12, 13 and 14. The middle one 13 of these contacts is connected by a lead 15 to one terminal of the motor 8; contact v12 is connected' to one terminal of the electromagnet 44j by lead 16,

while contact 14 is connected to one terminal of electromagnet 33 by lead 11. Slidable'in 'avcentral bore 18 in switch block 1I is a plunger 19, having a tiltable member 80 pinned at its upper end. Plunger 19 and member 80 are of conducting material, and are electrically `connected to.-

gether. They are connected to one terminal of the idler is caused to rotate on said member and l 88 normally maintains all contacts out of engagement. If member is manipulated so as to push vplunger 19 down without tilting member 80, contacts 13,. only will be engaged. This Will energize motor 8 and leave clutches 83 and 44 in engagement. Thus, as previously described, turntable -5 will be driven at `a progressively changing speed and the stylus head will follow the sound groove across the record. If now, while maintaining plunger 19 pressed in, member 80 is tilted to the right about its pivot, causing contact 81 to engage contact 14, electromagnet 33 will be energized in addition to motor 8, caus-v ing clutch 26 to be disengaged and the stylus head to back space, as previously described. -On the other hand, if member 80 is tilted to the left, contactv 86 will engage contact 12, energizing magnet 44 and disengaging clutch 39. 'This causes the stylus head to advance rapidly as previously set forth. The switch is so arranged that contacts 12-86 and 14-81 can not be engaged simultaneously. l

What is claimedis:

1. In a variable ratio transmission, a pair of rollers having diverging axes, anidler engaging the surfaces of said rollers andA forming-a driving connection between the rollers, means to drive one of said rollers, means whereby the other' roller is operatively connected to a load, and i other roller is operatively -connected'to a load,

means, rotatably supporting the. idler including a threaded member, the idler threadedly engaging said memberand being coaxial therewith,

said member being so located that the idler isV always in contact with the rollers, and whereby to travel along its axis.

3. In al variable ratio transmission, a pair of rollers having diverging axes, an idler engaging the surfaces of said rollers and forming a driving connection between the rollers, means to drive one of said rollers, vmeans whereby the other roller is operatively connected to a load,

means, rotatably supporting the idler, including a-threaded member, the idler' threadedly engag= ing said member and being coaxial therewith,

'said member being so .located that the idler is always in contact with the rollers, means to cause relative rotation between the idler and said mem'- ber, and means whereby said relative rotation may be optionally in either direction to cause the travel of the idler along its axis to be reversed.

4. In a variable ratio transmission, a pair of rollers having diverging axes, an idler engaging the surfaces of said rollersand forming a driving'connection between the rollers, means to a source of current 8| as by ground connections 75 drive one of said rollers, means whereby the other roller is operatively connected to a load, means. rotatably supporting the `idler including a rate of rotation of'the idler with respect to the member, whereby the rate of movement ofthe idler along the member may be varied.

5. In a variable-ratio transmission including "a pair of rollers, one of said rollers being tapered,

one of said rollers being operatively connected to a load, the other roller being eonnectedto a source of power, a threaded member, means r'otatably supporting said member, means whereby said member is driven by said source of power, an idler structure threadedly engaging said member and rotatably supported thereby, saidstructure having a surface frictionally engaging the rollersurfaces and coaxial with the member,

the speed of rotation of the threaded member being different from the speed of rotation of the idler, whereby the idler is caused to move along said member, and means to alter the speed of the driven roller whereby the speed of rotation of the idler with respect to the member is altered and the rate of movementxof the idler structure is changed.

6. In a Variable ratio transmission including a pair of rollers, one of said rollers being tapered,

one of said rollers being operatively connected to a load, the other roller being connected to a source of power, a threaded member, means rotatably supporting said member, means whereby said member is driven by said source of power, an idler structure threadedly engaging said member and rotatably supported thereby, said structure having a surface frictionally engaging the roller surfaces and coaxial with the member, the

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speed of rotation of the threaded member being normally less than' the speed of rotation of the idler, whereby the idler is caused to move along said member, and lmeans to reduce the speed of the idler below that of the member whereby the direction of its movement along the member is reversed. Y

'7. In a variable ratio transmission including a pair of rollers, one of said rollers being tapered, one of said rollers being operatively connected to a load, the other roller being connected'to a source of power, a threaded member, means rotatably supporting said member, means whereby said member is driven by said source of power, an idler structure threadedly engaging said member and rotatably supported thereby, said structure having a surface frictionally engaging the roller surfaces and coaxial with the member, the

speed of rotation of the threaded member being normally less than the, speed of rotation of the idler, whereby the idler is caused to move along said member, vand means to reduce the speed of said member, whereby the rate of movement of the idler therealong due to its rotation is increased.

8. A variable ratio transmission connectinga load with a source of power, said transmission including a pair of rollers, one of which has a surface of varying diameter, the other having a surface of constant diameter, and an idler, adapted to form a driving connection between the rollers, the ratio of said transmission depending on the axial position of said idler, means to alter the position `of the idler, and means forming a connection between the idler and the head, wherebythe position of the head with respect to the turntable is altered in response to movement of the idler.

FREDERICK D. BANNIN G.

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