US2085162A - Sound recording and reproducing mechanism - Google Patents

Description

June 29, 1937. c. w. LARNER 2,085,162

SOUND RECORDING AND REPRODUCING MECHANISM Filed Jan. 5, 1934 10 Sheets-Sheet l INVENTOR.

June 29, 1937. C. W. LARNER souun RECORDING AND REPRODUCING'MECHANISM Fild Jan. ,5, 1934 10 Sheets-Sheet 2 'INVENTOR,

June 29, 1937. c. w. LARNER SOUND RECORDING AND REPRODUCING MECHANISM Filed Jan. 5, 1934 10 Sheets-Sheet 4 N V EN TOR. MQ'RW A TTORNEY.

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June 29, 1937. c. w. LARNER 2,035,152

SOUND RECORDING AND REPRODUCING MECHANISM Filed Jan. 5, 1934 1O Sheets-Sheet 7 Bmy 53:.

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c. W. LARNER SOUND RECORDING AND REPRODUCING MECHANISM Filed Jan. 5, 1934 10 Sheets-Sheet 8 INVENTOR.

June 29, 1937. c. w, LARNER 2,085,162

SOUND RECORDING AND REPRODUCING MECHANISM Filed Jan. 5, 1954 10 Sheets-Sheet 9 &

INVENTOR.

June 29, C. W. LARNER SOUND RECORDING AND REPRODUCING MECHANISM Filed Jan. 5, 1954 10 Sheets-Sheet 10 IN VEN TOR.

Patented June 29, 1937 UNITED STATES SOUND RECORDING AND REPRODUCING MECHANISM Chester W. Larner, Philadelphia, Pa.

Application January 5, 1934, Serial No. 705,314

20 Claims.

In the art of sound recording and reproducing mechanism, one of the most important problems has been that of increasing the capacity and playing time of disc records. In this respect the only improvement which has been adopted commercially has been accomplished by reducing the R. P. M. of the records. This necessitates reducing the minimum speed of the needle in the groove of the record and it is impossible to accomplish much in this way without resulting in a deterioration in the quality of reproduction. The minimum speed of travel of the needle in the groove is the determining factor in this problem and it is obvious that, if the record is rotated at constant R. P. M., the speed of the needle in the groove will be at all times higher than necessary until the needle has reached the final and innermost groove, assuming that the needle starts in the outermost groove, as is usual.

Hence it is clear that the capacity of a record can be increased to a maximum only by arranging a variable speed drive such as to effect a constant speed of the needle in the groove,

this speed being the minimum which will give a reproduction of'satisfactory quality. A 12" record operating at constant needle speed will play about twice as long as at constant R. P. M.

However, all records so far produced have been of the constant R. P. M. type and there are im- 30 mense quantities of these records in the hands of the public so that any type of reproducing machine to be generally accepted must be capable of playing the existing constant R. P. M. records as well as constant needle speed records;

" One object of my invention is to provide a compact and dependable mechanism for recording and reproducing disc sound records at a constant speed of the needle in the groove.

Another object of my invention is to provide a W mechanism capable of recording and reproducing disc sound records at a constant needle speed and also at a constant R. P. M.

' Another object is to provide a mechanism of Fig. 3 is a fragmentary cross-sectional side view of Fig. 2.

Fig. 4 is a view in elevation of an alternate arrangement of the mechanism shown in Fig. 2.

Fig. 5 is a fragmentary cross-sectional side 5 view of Fig. 4.

Fig. 6 shows three views of the driving pinion and shifting block of Fig. 1.

Fig. 7 is a cross-sectional elevation of a sound recording and reproducing mechanism utilizing 10 a spiral gear of the conical worm type.

Fig. 8 is a cross-sectional plan of Fig. 7 taken substantially on the line 88 showing the worm track as if it were circular instead of spiral in order to simplify the drawings. 15

Fig. 9 is a cross-sectional elevation of a sound recording and reproducing mechanism utilizing a spiral gear of the conical spur gear type.

Fig. 10 is a cross-sectional plan of Fig. 9 on the line Ill-Ill with the spiral gear omitted.

Fig. 11 is a cross-sectional elevation of a modification of Fig. 1 showing a method of automatically resetting the spiral gear to the proper starting position.

Fig. 12 shows a modification of the resetting cams or nuts of Fig. 11.

Fig. 13 is a cross-section on line I3l3 of Fig. 11 and shows a modified detail of the resetting cams or nuts.

Fig. 14 is a diagrammatic representation of the spiral gear track used in Fig. 1.

Fig. 15 shows a modification of Fig. 14.

Fig. 16 shows radial and circumferential crosssections through the spiral gear track of Fig. 14.

Fig. 1'7 shows a cross-section in elevation of an arrangement similar to Fig. 1 illustrating a method of using a spiral gear track in combination with two circular gear tracks for playing two sets of constant R. P. M. records recorded at .=diflerent speeds. It alsoshows an alternative method 01' playing the two sets of constant R. P. M. records by means of a gearshift and an electrical means of resetting the spiral gear at the proper starting point. Fig. 18 shows the electrical circuit for control- 5 ling a motor drive in combination with the electrical resetting means of Fig. 17. v

Fig. 1 shows one form of my invention. The mechanism is contained in a circular housing I fitting into the top board 2 of the case in which it is mounted. The housing I has radial ribs 3 which support the bearings 4 and 5 for the shaft 6 which drives the turntable l which carries the record 8.

The disc 9 is rotatably mounted on shaft 6 and runs on the rollers I0 of which three or more are provided, supported by the ribs 3 or in any other convenient manner. A spiral rack or groove provided with gear teeth I I is cut or impressed in the lower face of 9 and these teeth mesh with a gear pinion I2 on the shaft l3. Shaft I3 is driven by a worm wheel I4 which is in turn driven by a worm I5. Worm I5 is driven directly or through intermediate gearing by a constant speed electric motor as is-customary in the art. Disc 9 has a cover I6 provided with a knob I! located opposite the beginning of the outer groove of the spiral track. Knob I8 is in line with the axis of pinion I2 and when knobs I I and I8 are togethen'or approximately so, the spiral gear track is in proper position to begin playing a record.

The outer circumference of disc 9 is provided with gear teeth meshing with pinion I9 driving countershaft 20 which, by means of sprocket 2|, chain 22 and sprocket 23,'drives shaft Gand turntable I. The proper gear ratio between disc 9 and turntable I depends upon the size of 9 relative to I and. the ratio between the radial pitch of the spiral gear and that of the grooves on the record. In Fig. 1, A, B, C and D are the radial distances, respectively, of the outermost groove on the record, the innermost groove on the record, the pitch line of the outermost spiral gear track and the pitch line of the innermost gear track and if A C and B=D, then the gear ratio equals the pitch ratio. In other words, if the pitch of the grooves on the record is 0.01" and the pitch of the spiral gear is 0.25", then the'gear ratio is 25:1. Fig. 17 illustrates the case where 21:6 and B=D.

In order to effect a constant speed of the needle in the groove, the relation A:C=B:D must be maintained but if ,A is notequal to C the gear ratio is no longer equal to the pitch ratio. This is the case in Fig. 1.

Suppose C'=0.8A. Then the gear ratio must be If the gear pitch is also reduced proportionately so that the number of gear tracks is unchanged, the gear ratio will remain unchanged.

The spiral gear track and the groove on the record are both true spirals and hence if the relation A:C ='B:D is maintained so that the pinion I2 will be at radius D when the-needle reaches radius B, it follows that travel of the needle in the groove will have the same characteristics as the travel of the pinion I2 in the spiral gear. Pinion I2, being driven by a constant speed motor, rolls around the spiral gear track at constant speed and therefore the needle travels at constant speed i. the groove of the record. I

The general relations, mathematically expressed are as follows:

Assuming A:C'=B:D I

Let m=radial pitch of needle groove on record.

n=radial pitch of spiral gear track. t==linear speed of needle in groove. v=peripheral speed of pitch circle of pinion I2. Then :2 A t 51 6 v In connection with the several disclosures of this invention, it is necessary tov consider at least three types of disc records, hereinafter referred to as X, Y and Z.

Type X is the 78 R. P. M. record which has been made for many years. This record has a minimum needle speed of about 1000 inches per minute.

Type Y is the more recent 33% R. P. M. record which has a minimum needle speed of about 500 inches per minute.

Type Z is a proposed type of record to be made at a constant needle speed which would be the minimum needle speed suitable for good sound reproduction. Under present conditions this would probably be the same as for Type Y, namely, about 500 inches per minute.

To play a Z record on the mechanism of Fig. 1 the pinion I2 is set inthe position shown by means hereafter described. The driving motor is started and the needle set in the outer groove of the record. The pinion I 2 is slidably mounted on shaft I3 and driven by key 24. As it rotates, the pinion is fed toward the center of disc 9 by the spiral groove I I into which it is meshed and it is which engages the pinion by means of a forked end provided with pins which fit into grooves 21 on each side of a square collar 28 which is rotatably associated with pinion I2 as shown in Fig. 6. It will be noted that one face of pinion I2 has a convex form to fit the concave outer periphery of the spiral track in which it runs. As already explained, the rotation of pinion I 2 in spiral track I I rotates the record 8 at a uniformly accelerated speed and maintains a constant speed of the speed of rotation which would give a minimum needle speed approximately the same asthe constant needle speed used for Type Z records. Thus the position of circular track 29 would naturally coincide with the inner end of track II.

This arrangement is better illustrated in Fig. 14, wherein the heavy lines and blackened areas indicate partitions separating the gear tracks. This figure is diagrammatic and shows the gear track viewed from below.

The partition between II .and 29 gradually tapers until it ends at 30. The space. 3| is conmon to both I I and 29 and is long enough to permit pinion I2 to shift from II to 29 as a result of the tension of spring 25. This change therefore occurs automatically and pinion I2 will continue to run in track 29 until it is manually track 29 which is the same as the pitch of II.

The teeth of pinion I2 must be loose enough to rod 46 to lever 41.

to the radial pitch minus the thickness of the partition, is machined in the face of disc 9. A gear rack 35 is then made in sections of convenient length to fit into the spiral groove and it is bent into spiral form and fastened in place at suitable intervals by rivets 36. The teeth of rack 35 and pinion I2 should be sufficiently rounded or pointed so they will fall into mesh readily and the partition 34 should extend somewhat beyond the rack 35 so that the pinion l2 cannot move radially even though it fails to mesh with rack 35. It will then be in position to mesh as soon as pinion I2 starts to turn. I

To reset pinion l2 for playing another Z record, the first operation is to push down button 31 on rod 38, depressing'one end of lever 39 which is pivoted in a bearing'4ll mounted on the bottom 4| of the phonograph case. This lifts the pivot bearing 42 which in turn lifts shaft 6 and disc 9 'sufficiently to clear pinion I 2. Then, while holding down button 31 with one hand, the resetting lever which operates lever 26 is thrown over with the other hand, shifting pinion 12 to the starting position as shown in Fig. 1. Button 31 is then released, dropping disc 9 and locking pinion I2 in position shown in Fig. 1.

The mechanism which operates "lever 26 is shown in Figs. 2, 3, 4 and 5. The rocker shaft 43 carried in bearings 44 and keyed to lever 26 is also keyed to a lever 45 which is connected by Lever 41 is keyed to rocker shafts 48 (Figs. 2 and 3) .which is in turn keyed to lever 49. When lever 49 is thrown to the left, pinion I2 is set at the starting point; when thrown to the right pinion l2 goes to the position shown in broken lines, Fig. 1. This is the position for playing Y records Lever 49 swings automatically from left to right during the playing of. a Z record. It also swings automatically from left to right whenever button 31 is pressed down because, whenever pinion I2 is released by the lifting-of disc 9, the tension of spring 25 throws it over.

Obviously to set pinion l2 to play a Y record it is necessary merely to press down button 31 and release it. After playing a Y record no resetting is necessary to play another Y record.

. In resetting to play Z records, it is also necessaryto turn disc 9 until knobs I1 and I8 are opposite, or approximately $0.. This brings pinion l2 into mesh with the beginning of the spiral groove lever 52 so that 52 may slip up and down in it' and when 52 is thrown one way or the other, shaft 56 is rotated. On the end of 52 is a cam 53 which engages a cam 54 on the end of a pin 55. When 52 is pushed down through 5|, 53 pushes against 54, pushing 55 down against the end of lever 39 and raising disc 9. This unlocks pinion l2 and lever 52 may be thrown to a new position. The lower face of cam 53 is shaped to conform to a radius struck from the center of shaft 56 when the cam is depressed to the lower position indicated in dotted lines. In this way, after lever 52 has been pushed down, the cam 53 countershaft 69, pinion I0 and gear H.

'plained in connection with Fig. 1.

which it engages is constant.

has no further effect on cam 54 when lever 52 is swung from one position to another.

An alternative shifting arrangement is shown in broken lines in Fig. 2 where the lever 56 is keyed to a prolongation of shaft 43, bringing lever 56 into the'same plane in which lever 49 is shown by Fig. -3.

Figs. '7 and 8 show another embodiment of my invention which utilizes a different form of spiral gear. The cylindrical housing 51 has radial ribs 58 which support bearing 59 and two generally circular parallel flanges 66 and GI, both of which are provided with projections 62 to guide the worm bearings 63. The latter are of rectangular cross-section, made in halves to permit introduction of the worm shaft 64 and finished to fit slidably between flanges 60 and 6| Shaft 65 which drives turntable 1 is itself driven by sprocket 66, chain 61, sprocket 68, Gear H rotates in bearing 12 which is connected to flange 13 by ribs 14. Flanges 6| and 13 are rigidlyconnected together. Shaft 65 rotates freely in a tubular shaft 15 which is keyed to gear ll. Sprocket 66 is non-slidably mounted on shaft 65 and the weight of both shafts and connected parts is carried on pivot bearing 16.

The spiral gear 11 is of conical form having worm teeth 18 out around its periphery in a spiral track which terminates at the small end of the cone in circular track 19. The track is cut by a cutter, having the same form as the worm 80, which is held in the same position relative to the cone as the worm and is fed axially of the cone at the proper rate while the cone is rotated at the proper rate. The track is cut to the depth of the radius of the worm so that, when the worm is engaged, it locks 11 against axial movement.

' Gear track 19 is used for playing Y records and 18 is used for Z records. The gear ratios are determined according to the principles ex- Spiral gear "is keyed to shaft 15 so as to permit axial movement of 11. Worm 86, which rotates in bearings 63, is driven by shaft 64. Shaft 64 is connected to the shaft of wormwheel l4 by a universal joint 95 so that shaft 64 and worm 80 can swing in a horizontal plane. Worm 86 is driven at constant R. P. M. and hence the peripheral speed of the spiral gear Bearings 63 are connected by a T-frame 8| which extends through an opening in 51 and engages with a lever which pivots at a bearing 83 and extends upward through an opening in 2 so that it may be manually operated, the same as lever 49 of Fig. 2. When lever 82 is swung on the pivot 83, lever BI swings with it, thus causing worm 80 to approach or ,recede from the spiral gear ,track. Spring 64 holds the worm in engagement with the gear when not under control of lever 82.

To play Z records, the worm is set in the gear track at the large end of the cone. The motor is started and gear 11 is rotated. Inasmuch as the turntable is running at constant R. P. M.,

suitable for playing Y records. Gear [1 drives gear H by means of key 86 in shaft 15, which is common to both.

To reset the spiral gear for playing Z records,

lever 82 is thrown to the left thus withdrawing worm 88 radially to a distance sufiicient to clear the largest diameter of gear I1. Button 81 is then pressed down, shifting gear TI to the position where worm 88 is opposite the beginning of the spiral track at the large end of 11. This is the position shown in Fig. 7. Lever 82 is then released and spring 84 throws worm 88 into engagement with gear TI and locks TI against vertical movement so that button 81 may be released.

Button 81 operates to shift gear 'I'I through rod 88, lever 89 and block 98 which is ro-tatably but not axially movable on-'gear Il. Lever 89is made of two spaced bars to straddle shaft 89. It works on a fulcrum 9I which is supported from housing 51. It is connected at one end to rod 88 and spring 85, and at the other end it has a yoke 92 which straddles block 98 and is connected to it by pins 93 which slide in grooves 94. By this means lever 89 is capable of raising and lowering gear 11, at the same time leaving it free to rotate.

To reset the gearing to play Y records it is only necessary to throw lever 82 to the left and then release it. The tension of spring will automatically shift gear 11 so that the worm 88 will fall into engagement with track I9. To continue playing Y records no resetting is necessary.

Figs. 9 and. 10 show another embodiment of my invention which utilizes a spiral gear of conicalform which engages a spur gear instead of a worm, as illustrated in Figs. 7 and 8. In this case the spiral gear has no vertical movement, the shift being accomplished by two motions of the driving pinion, one vertical by depressing a button and the other radial by swinging a. lover.

The housing 95 has ribs 98 and 96' which support bearing 91. Bearing 91 contains the lower end of shaft 98 which drives turntable I. The weight of shaft 98 and connected parts is carried on pivot 99. Shaft 98 is driven by sprocket I88, chain I8I, sprocket I82, countershaft I83 and pinion I84. Pinion I84 is driven by gear I85 which is keyed to a tubular shaft I86 which revolves on shaft 98 and guides the upper end of 98. Gear I85 runs on three or more rollers I8 which are supported from the housing 95 in any suitable way. These rollers maintain gear I85 in proper alignment.

Spiral gear I 88 abuts against gear I85 and drives it by means of key I8'I which is common to both. Gear I88 is of conical form having a spiral gear on its periphery as shown. This gear may be formed by cutting spiral steps in the surface of the cone and wrapping a gear rack around the steps, fastened in place by rivets or other suitable means. In that case the teeth I89 make a slight angle with the teeth of the driving pinion II8 but-the latter are made sufficiently loose so that this discrepancy is immaterial. The spiral track I89 ends in a circular track III which is used for playing Y records.

The relations governing ratios of gearing between I 88 and I, which were explained in connection with Fig. 1, apply in this case also.

Pinion II8 is driven by shaft II2 through a pair of bevel gears H3 and H4. Shaft H2 is driven by shaft I I5 through a pair of bevel gears Band III. Swinging arm II8, having brackets and bearings at each end, supports pinion II8, bevel gears II3, I I4, H6 and Ill, and shaft H2 in proper relation to each other. freely on shaft II5, permitting pinion II8 to approach or recede from gear I88 in a radial di- Arm II8 swings rection. This motion is accomplished by means of a projecting lug II9 on arm II8. Lug II9 passes through a slot in lever I28 so that, when leverv I28 is swung on its pivot 22I, arm II8 swings as indicated in Fig. 10. Spring I2I, connecting arm II8 to the opposite side of housing 95, holds pinion II8 in engagement with the gear track on gear I88 except when it is displaced by swinging lever I28.-

Arm II8 is also slidable vertically on shaft II5 to permit pinion I I8 to work up and down on gear I 88. Bevel gear I I! has a key in its bore which slides in the keyway I22 so that I" is driven by shaft I I5 in'all positions. Shaft II 5 is driven at constant speed by a constant speed motorthrough worm shaft I5 and worm wheel M. The lower end of bearing I23 on the end of arm H8 is provided with a shifting block I24, similar in design to 28 of Fig. 6, which engages pins I25 in the forked end of lever I26, which thus serves to raise and lower arm II8. Arm II8 is automatically urged upward by the tension of spring I27 acting on lever I26. In order to lower arm II8, button I28 on rod I29 is pressed down. Rod I29 is connected to lever I39 which engages one end of lever I28. The fulcrum I3I of lever I26 is supported by rib 96 and the fulcrum I32 of lever I38 is supported by bearings I33.

To play Z records, lever I 28 is swung in the proper direction-t0 release pinion II8 from engagement with gear I88. Spring I21 then acts upon lever I28 toraise arm II8 until bearing I38 strikes against bearing I35. This brings pinion II8 opposite the beginning of the gear track on I88. Lever I28 is then released and spring I 2| brirgs pinion II8 into engagement with gear I88. The motor is then started and. pinion II 8 rotates I88, being fed downward by the spiral shoulder I36 until it runs onto the circular track I I I. When it is in track III it is set to play Y records.

If the pinion is in anyposition above track III and it is desired to play Y records, button I28 is pressed 'down and inward against spring I31 until collar I38 latches under lug I39. This sets pinion I I8 in track II I and holds it there. To reset for playing Z records after playing Y records collar I38 must be unlatched, otherwise spring I21 will be ineffective.

In respect to all three arrangements shown in Figs. 1, .7 and 9, it will be noted that the housing containing most of the mechanism can be withdrawn through the opening in the. top of the case by disconnecting only a few parts. This is a great convenience in case of repairs.

Also in each case the Working parts are readily accessible for lubrication, cleaning and adjustment. The turntable I can be removed in each case by unscrewing cap I36 which centers the record. 'In Fig. 1, the dustcover I8 with gear 9 attached can then he slipped off shaft 6 and removed. This leaves practically all of the mechanism exposed. Similarly, in Fig. '7, dustcover I8 with gear II attached may be removed 'and, in Fig. 9, dustcover I8 with gear I85 attached may be removed.

In the foregoing description of the spiral gears, methods have been described for providing machine finished teeth.' This is not necessary except in the case of Fig. 7. 'In Figs. 1 and 9 the gears can be made by various well known methods for accurate casting or diestamping in a variety of materials. Extreme accuracy is unnecessary inasmuch as the teeth must fit loosely with the driving pinion. If light materials are used, it. may be necessary to add weight to the dustcover I6 in the cases of Figs. -1 and 9 to hold the gears properly meshed. This is particularly true of Fig. 1 when pinion I2 tends to lift gear 9.

In none of the figures has any attempt been made to show' the connections to the motor because they would vary withthe speed of the motor and its location. These connections are familiar to those informed in the art.

Also various combinations of gearing may be utilized to connect the spiral gear to the turntable shaft, provided the combination effects the proper gear ratio. Thus, for example, the sprockets might be replaced with spur gears and an idler'gear placed between them, in this way dispensing with the chain.

In the recording and playing of Z records, it is not necessary to start the needle at the outer edge of the record and feed it toward the center. In Fig. 1, for example, the needle may start at radius B and stop at radius A, or thereabouts, depending on the length of the record. In that event, however, the pinion I2 must move in the same direction, starting at radius D and moving toward radius C. This would, of course, necessitate some changes in the shifting mechanism. Spring 25 would have to act in the opposite direction in order to start pinion I2 out of the circular track 29 and into the spiral track I I. Also it would be necessary to provide a means of locking pinion I2 in track 29 for playing Y records. Various means of accomplishing these results will be obvious to those skilled in the art.

Resetting the spiraLgearF-In recording and reproducing Z records, it is desirable that the driving gear or pinion should be started at the beginning of the spiral gear track, or approximately so. If a recgrd is made in this way and, when being played, the gear is started at some other point in the spiral track, the speed of, the needle in the groove will not be the same as the speed at which it was recorded- Some deviation in this respect is permissible without aflecting the quality of reproduction but not very much. 4

In all of the arrangements shown, thestationary knob I8 and the knob I1, which rotates with the spiral ,gear, are so located that, when they are in juxtaposition, the driving gear or pinion is set to enter or mesh at or near the beginning of the spiral gear track. Thisstarts the spiral gear and the needle in the proper relation to each other. However, the playing length of records differs and therefore it is impossible to arrange to have knob I1 stop opposite knob I8 when the driving motor is stopped at the end of the record. It is therefore necessary, when preparing to play a Z record, to reset the spiral gear so that knobs I1 and I8 are opposite, or approximately so. Precision in this respect is unnecessary. For example, if playing 12" records with A=C' and knob I1 should be 3 inches away from knob I8, the result would be that the spiral gear would be about of a revolution away from its correct position. Assuming a gear ratio of 25:1 this would mean that the record would have made about 2 revolutions while the knob I1 was moving 3 inches beyond knob I8 and therefore if the needle is started in the outer groove of the record when I1 is 3 inches beyond I8, the needle will be two grooves farther from the center of the record than it should be. This discrepancy would have no appreciable effect on the quality of sound reproduction. To play constant R. P. M. records X and Y the driving gear or pinion is not using the spiral track and hence with them no resetting of the spiral gear is necessary. It is necessary only with Z records.

The spiral gear of Figs. 1, 7 and 9 may be reset by hand. Pinions I9, 10 and I04 are not keyed to the countersha'ft. The latter is driven by a so-called free-wheeling clutch I40 of well known construction which permits the pinion to turn freely in the reverse direction. It is therefore possible to turn the spiral gear backward by hand until knobs I1 and I8 are opposite. This is, of course, done with the spiral gear disengaged from the gear which drives it.

Another method of resetting is illustrated diagrammatically in Fig. where the heavy lines and blackened areas represent partitions separating the gear tracks of a spiral gear similar to 9 of Fig. 1; In Fig. 15 a circular track MI is added surrounding the spiral track II with a partition I42 between them. Partition I42 is .cut away at the beginning of spiral track II sufficiently to allow pinion I2 to shift from track I4I to track II as soon as it reaches the opening I43. This is efiected by the tension of spring 25.

When starting to play a Z record, pinion I2 is meshed in track MI and the driving motor started but the needle is not applied to the record until knobs I1 and I8 are opposite. Knob I1 is opposite the center of space I43 and hence the position of the needle on the record and the position of pinion I2 in spiral groove H have the proper relationship.

Fig. 11 shows a means of resetting the spiral gear automatically during the operation of lifting it preparatory to resetting pinion, I2. The shaft I44, which drives turntable '1, passes through a tubular shaft I45 which is keyed to spiral gear 9 and rotates with it. A collar or nut I46 having a helical face-I41 is fixed on shaft ,I45. The helix has a steep pitch and makes one revolution. beginning and ending at the verticalface I48 which projects radially from shaft I45. Nut I46 turns with spiral gear 9. A similar nut. I49, having a vertical face I50 and helical face I5I, complementary to I41 and I48 of nut I46, is slidably mounted on shaft I45 but is held from turning by the double lev'er I52 which is used to raise and lower it. The vertical faces I48 and I50 are in alignment when knobs I1 and I8 are together.

To reset the spiral gear with this mechanism,

button 31 is pushed down lifting nut I49 by means of rod I53 provided with a pin I54 which engages levers I52 which are slidably fulcrumed by a bridge I55 supported between ribs I56. When face I5I of nut I49 engages face I41 of nut I46, the first eifect is to lift nut I46 which in turn lifts shaft I45 and spiral gear 9 until the top of nut I46 engages the bottom of bearing I51. This disengages pinion I2 from the spiral gear track. The helical faces I41 and I5I, if well lubricated, thenhave a tendency to turn on each other but, since nut I49 cannot turn, all of the motion is imparted to nut I46 which turns until face I48 comes against I50. Spiral gear 9 turns with nut I46, the helix being so formed as to produce rotation of 9 in the reverse direction so that clutch I40 does not drive countershaft 20, as previously explained. After I48 and I50 come together, rotation is, of course, checked and knobs I1 and I8 are together. Button 31 is then released and spring I51 returns nut I 49 to the position shown in Fig. 11, spiral gear 9 dropping into mesh with pinion I2.

Fig. 12 shows an alternative arrangement o the two nuts wherein a wheel I58 is used, projecting slightly below the helical surface of nut I46. This wheel rides around the helix of nut I49, preventing the two surfaces from touching and reducing the frictional resistance materially. It is desirable to minimize friction because otherwise the pitch of the helix must be very steep Which makes the nuts long and increases the vertical space occupied by the mechanism. The friction is greatest when the two helixes lap only slightly as would be the case in Fig. 11if the face I48 were turned slightly to the left from the position shown. To overcome this difiiculty a spring I59 is attachedto one of the ribs I56 so as to be deflected by a pin I60 in nut I46 as the latter passes the position shown in Fig. 11. If nut I46 stops while still engaged with spring I59. the latter will start nut I46 rotating in the reverse direction when button 31 is depressed and the pitch of the helix will continue the motion.

Figs. 17 and 18 show a method of resetting the spiral gear by means of the electric motor drive. A slip ring I60 with two contact brushes lI6I and I62 is attached to dust cover I63 with insulation I 64 as shown. Slip ring I60 is provided with an insert of insulating material I65 which breaks the circuit through the ring when it covers brush I6I. I

Fig. 18 shows a diagram of the electrical circuits for controlling the mechanism of Fig. 17. The motor I66 which drives shaft I (Figs. 1, 7, 8, 9 and is connected to the source of current through two circuits, one controlled by the switch I61 and the other controlled by the slip ring I60. Switch I61 is the usualform of starting switch and is located adjacent the record turntable so that, when the needle reaches the last groove onjthe record, the needle arm opens switch I61. Opening switch I61, however, does not stop the motor since current continues to fiow through the slip ring until the insulated gap I65 blanks brush I6I. The motor then'stops.

Line S-S passes through knobs I1 and I8 and locates the properstarting position of the spiral Insulation I65 and brush I6I should be gear. so placed in respect to each other that, allowing for the over-run I69 after current is cut off from the motor, the line S S will pass through both knobs I1 and I8, or approximately so. This leaves the spiral gear set in the proper position .for playing a new record.

I6I will not stop the motor as long as switch I61 is closed, as it is during the playing of a record,

It is undesirable that the record should continue to revolve after the needle reaches the last groove and while the spiral gear is turning around to its starting position because this would cause an unpleasant scratching sound. It is, therefore, desirable to use the customary friction brake acting on turntable I which is set by the needle arm at the same time it opens switch. I61. The use of this brake is made possible by mounting pinion I69 rotatably on countershaft I10 and driving the latterby means of a friction clutch so adjusted that it is tight enough to drive turntable I when there is no resistance except the drag-of the needle on the record but not tight enough to drive it when the brake is set by the 7 needle arm. Turntable I then stops at the end of the record but the spiral gear continues to run until knobs I1 and I8 come together.

The friction clutch consists of a driving element I1I keyed to countershaft I10 and held radius B and ending in a circular track I80. -Anothercircular track I11 is provided at radius E.

Track I16 is used with Z records, track I80 with Y records and track I11 with X records. The mechanism for shiftingpinion I2 must be modified to provide for setting the pinion in the three starting positions. countershaft I10 drives shaft I19 as shown in Fig. 1.

The other method dispenses with track I11 and substitutes an additional chain drive for I19. The sprockets 216 and IN are rotatably mounted on shaft I10 and are provided with clutch teeth which will mesh with the teeth on collar I83.

To play Y or Z records, lever I 84 is thrown to the position shown. Lever I85 takes the position shown, due to the pressure ofspring I86, and block I83, which is driven by shaft I10 through a feather key, comes into engagement with sprocket 216, thus driving shaft I19 through chain 211 and sprocket I18. The gear ratio between sprockets 216 and I18 is suitable for Y and Z records.

To play X records, lever I84 is thrown to the right against stop I81, forcing block I83 down into engagement with sprocket NH and releasing sprocket 216. Shaft I10 then drives shaft I19 through sprocket I8I, chain I 82 and sprocket I18. The gear ratio between I8I and I18 is suitable for playing X records.

In both cases, the mechanism for'resetting pinion I2 may be similar to that for Fig. 1 and the spiral gear may be reset by hand, by means of the outer circular groove or electrically, all these methods having been previously described.-

In the foregoing desciption, it has been stated that the radius D is the radius of'the end of the spiral gear track for playing Z records and also the radius of the circular gear track for playing Y records. This, of course, assumes that. the spiral gear track continues in to that radius and merges with the circular track.

In practice that is impossible for two reasons as will be evident from Fig. 14. In the first place,

' after pinion I2 passes the end of partition 34 at 30, spring 25 pulls it into track 29. The blackened area 260 represents the continuation of the spiral track II which has been filled in by a solid partition because it cannot be utilized.

Second, even if it were possible to hold pinion I2 in the spiral path for a complete turn from point 30 back to point 30, as, forexampl'e, by reversing the pull of spring 25, the effect would be the same as it is with the arrangement shown in Fig. 14. This is due to the fact that from point 30 onward the teeth in the spiral track would have to be radial extensions of the teeth in the circular track and, therefore thesrotative speed of gear 9 would be the same whether pinion I2 were working in the blackened area 200 or in track 29.

It is undesirable to utilize the track beyond point 30 for playing Z records'on account of the speed. change which occurs at this point, as previously explained. The best arrangement is to make the needle speed of Z records equal to the minimum needle speed of Y records and not record on the Z records beyond the point which would correspond to point 30 on the spiral gear.

It will be obvious to those skilled in the art that various changes may be made in the app-aratus herein described without departing from the spirit of the invention as set forth in the accompanying claims. No attempt has been made to show the needle used in connection with the disk records, the arm which holds the needle, the brake which stops the turntable or the mechanism by means of which the needle arm opens the starting switch to stop the motor at the end of the record. All of these devices and apparatus are too well known in the art to require illustration or description.

I claim:-

1. In a mechanism for'rotating a sound recording or reproducing disk, the combination of a turntable non-rotatably mounted on a shaft, a spiral gear rotatably mounted on said shaft, a constant-speed gear for driving said spiral gear, and gear mechanism whereby said spiral gear drives said shaft and rotates said turntable at a uniformly increasing or decreasing angular velocity.

2. In a mechanism for rotating a sound recording or reproducing disk, the combination of a turntable non-rotatably mounted on a shaft, a gear element rotatably mounted on said shaft and having a spiral gear track and a circular gear track, a constant-speed driving gear arranged to mesh alternatively in either of said gear tracks, and gear mechanism whereby said gear element drives said shaft and rotates said turntable at a constant angular velocity or at a uniformly increasing or decreasing angular velocity.

3. In a mechanism for rotating a sound recording or reproducing disk in contact with a needle, the combination of a turntable non-rotatably mounted on a shaft, a gear element rotatably mounted on said shaft and having a spiral gear track and a circular-gear track, a constant-speed driving gear arranged to mesh alternatively in either of said gear tracks, and gear mechanism whereby said gear element drives said shaft and rotates said turntable at a constant angular velocity. or at a variable angular velocity, said last named velocity being such as to maintain a constant linear velocity of the disk relative to the needle.

4. In a mechanism for rotating a sound recording or reproducing disk in contact with a needle, the combination of a turntable non-rotatably mounted on a shaft, a spiral gear rotatably mounted on said shaft, a constant-speed gear for driving said spiral gear, and gear mechanism whereby said spiral gear drives said shaft and rotates said turntable at a variable angular Velocity such as to maintain a constant linear travel of the disk relative to the needle.

5. In a mechanism for rotating a sound recording or reproducing disk in contact with a needle, the combination of a turntable to support the disk, a-constant-speed driving gear, gear mecha nism for transmitting the movement of said driving gear to said turntable to rotate it at a constant angular velocity, gear mechanism for transmitting the movement of said driving gear to said turntable to rotate it at a variable angular velocity such as to maintain a constant linear travel of the disk relative to the needle, and selective means for causing either of said gear mechanisms to become operative.

6. The combination of claim 5 further characterized in that the second named gear mechanism includes a spiral gear.

7. The combination of claim 5 further characterized in that the second named gear mechanism includes a spiral gear which is mounted concentrically in relation to the turntable and which rotates at a lower speed than that of the tumtable.

8. The combination of claim 5 further characterized in that said first named gear mechanism includes a circular gear track and said second named gear mechanism includes a spiral gear track one end of which merges into the circular gear track.

9. In a mechanism for rotating a sound recording or reproducing disk, the combination of a turntable, a constant-speed driving gear, a driven gear having a circular gear track and a spiral gear track, selective means for meshing said driving gear in either of said gear tracks, and means including gearing whereby said driven gear effects rotation of said-turntable.

10. In a gear transmission; the combination of a constant-speed driving gear; a driven gear provided with a circular gear track and a spiral gear track, said circular track being adapted to effect rotation of said driven gear at a constant angular velocity and said spiral track being adapted to effect rotation of said driven gear at a variable angular velocity; and selective means for positioning said driving gear to mesh in either of said gear tracks.

11. In a gear transmission; the combination of a constant-speed driving gear; a driven gear provided with a circular gear track and a spiral gear track, said circular track being adapted to eifect'rotation of said driven gear at a constant angular velocity and said spiral track I being adapted to effect rotation of said driven gear at'a variable angular velocity; means for disengaging said driving gear from said gear tracks; and selective means for positioning said driving gear to mesh in either of said gear tracks.

12. In a mechanism for rotating a sound recording or reproducing disk, the combination of a turntable, a spiral gear provided with a toothed track and connected by gearing to said turntable, a constant-speed gear for driving said spiral gear, meanslfor positioning said driving gear to engage said spiral gear, and means for positioning said spiral gear to engage said driving gear at a predetermined point in said track.

13. The combination of claim 12 further characterized in that the last named means. has provision for being manually operated.

14. The combination of claim 12 further characterized in that the last named means has provision for being electrically operated.

15. In a mechanism for rotating a sound recording or reproducing disk, the combination of a housing, a turntable non-rotatably mounted on a shaft, a gear disk rotatably mounted on said shaft and provided with a spiral gear track on one face and gear teeth around its periphery, a constant-speed motor driving a shaft positioned radially of said gear disk and parallel to said face thereof, a pinion slidably and non-rotatably mounted on said last named shaft and adapted to engage saidspiral gear track, gear mechanism whereby, said gear disk drives said first named shaft to rotate said turntable, means for maintaining said gear disk in alignment relative to said pinion, means for disengaging said pinion from said spiral gear track, and means for shifting said pinion radially of said gear disk.

16. The combination of claim 15 further characterized by the provision of means for rotating said gear disk independently of said turntable and said pinion.

17. The combination of claim 15 further characterized by the provision of means including said pinion for rotating said gear disk independently of said turntable.

18. The combination of claim 15 further characterized in that said motor is energized by means of two electrical circuits, one of said circuits being controlled by a switch and the other being controlled by a slip-ring connected to said gear disk, said slip-ring being provided with two brushes and having an insulating inset so positioned as to contact with one of said brushes at a predetermined point during the rotation of said slip-ring thereby breaking said. second named circuit. i

19. In a mechanism for rotating a sound recording or reproducing disk; the combination of 5 gear track adapted to effect rotation of said driven gear at a constant angular velocity, gear mechanism connecting said driven gear to said turntable and adapted to rotate saidturntable at either of two predetermined constant angular 15 velocities, and selective means for effecting rotation of said turntable at either of said predetermined constant angular velocities.

20. The combination of claim 19 further characterized in that said driven gear is provided with 20 two circular gear tracks, thereby being adapted to efiect rotation of said driven gear at either of two predetermined constant angular velocities.

CHESTER W. LARNER.

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