US2509811A - Tone arm control mechanism - Google Patents

Description

May 30,, WU

Filed May 25, 1945 C. B. DALE TONE ARM CONTROL MECHANISM 6 Sheets-Sheet l M S I N A H m ML mm T Em .0 m E N 0 T May 311, 1950 Filed May 25, 1945 may 3U 19% c. B. DALE ZfiW M TONE ARM CONTROL MECHANISM Filed. May 25,, 1945 s Sheets-Sheet &

y 39% c. B. DALE 509,11

TONE ARM common. MECHANISM Filed. May 25, 1945 6 Sheets-Sheet 4 m I: w 2 AK May 30, MO c. B. DALE 2,@ M

TONE ARM CONTROL MECHANISM Filed May 25, 1945 6 Sheets-Sheet 5 M S I N A H m W 0 D R .T Em .0 m A E N 0 T may 3%, 1959 Filed May 25, 1945 Patented May 30, 1956 UNITED STATES PATENT OFFICE TONE ABM CONTROL MECHANISM Colin 13. Dale, Oak Park, Ill., assignor to Webster- Chicago Corporation, Chicago, 111., a corporation of Illinois 13 Claims.

During a number of years the time of many men has been devoted to inventing and designing automatic record changers for phonographs in an effort to make them thoroughly reliable, simple to manufacture, and to provide various special features.

The present invention is believed to provide a simplicity never before approached with equal dependability and performance characteristics and also to provide even greater dependability than that which has heretofore been considered excellent.

Another advantage of the present invention is the extreme ease with which the tone arm swings even when it is operating the mechanism which controls the starting of a record changing cycle. This would always be important from the standpoint of reducing wear on the records, but with the trend toward lighter pick-ups, it is increasingly important. As the pick-ups become extremely light, their ability to stay down in the sound groove to exert a lateral thrust becomes less. According to the present invention, the tone arm swings with such extreme ease that there is room for almost immeasurable improvement in reducing the weight of the pick-up. Of course, any reduction in the weight of the pickup greatly reduces the wear on the records.

One of the features of the present invention which has greatly contributed toward the lightness of tone arm action is the reduction in size of the various cycle controlling parts and the balancing and mounting thereof in such a way that they may be moved with extreme case.

One feature which contributes greatly toward the simplification of the apparatus is using a single lever for first raising a tone arm and then turning it. This involves a double-acting cam as well as a doubly pivoted lever so that the cam first tilts the lever about a horizontal axis to raise the tone arm and then swings it about a vertical axis to swing the tone arm. Another important contribution towards simplicity is in varying the set-down position of the tone arm between the correct positions for or 12 inch records by simply shifting the bias of the cam follower or lever which swings the tone arm so that it is biased against an inside cam surface for one position and an outside cam surface for the other position.

It is easy to provide sufficient manufacturing accuracy so that the two different cam surfaces will space the two set-down positions the proper distance apart for the two record sizes. It is not practical, however, to position the parts with respect to one another with exact uniformity in successive machines. It is, therefore, necessary to adjust the tone arm position even though one adjustment may be made for both sizes of records at once. According to the present invention, however, the one necessary adjustment is greatly facilitated by providing the means for this adjustment in the tone arm for the greatest accessibility and so that the operator can see the effect the adjustment makes.

According to another feature of the invention the feeding of two records at once is reliably prevented by a special and simple construction of the spindle which nevertheless permits the played records to be withdrawn readily without removing the spindle. One form of this spindle will even permit the intermixing of ordinary records and records which are only half as thick as these records.

Additional objects and advantages of the invention will be apparent from the description and from the drawings; in which Figure 1 is a plan view of the form of the invention chosen in the illustration;

Fig. 2 is a perspective View of the push-off assembly;

Fig. 3 is a vertical sectional view, enlarged, taken approximately on line 3--3 of Fig. 1;

Fig. i is a horizontal sectional view looking upwardly approximately on the line i4 of Fig. 3;

Fig. 5 is a horizontal sectional View showing the structure which is below the turntable and taken approximately on the line 5-5 of Fig. 3;

Fig. 6 is a perspective View of the main control cam disc;

Fig. 7 is a sectional view taken approximately on the line 'l-'l of Fig. 3 and showing particularly the underface of the driving wheel for the control cam;

Fig. 8 is a fragmentary detail View showin the clutch dog in engaged position;

Fig. 9 is a fragmentary vertical sectional view, enlarged, taken approximately on the line 9- of Fig. 1;

Fig. 10 is a perspective detail view showing the tone arm control lever and the double pivoting thereof;

Fig. 11 is a perspective detail view, partly broken away, of the tone arm mounting, showing at the top thereof the eccentric adjustment screw for adjusting the set down positions of the tone arm;

Fig. 12 is a perspective view of the cycle-starting trigger;

Fig. 13 is a fragmentary vertical sectional view, enlarged, taken approximately on the line I3-l3 of Fig. 1;

Fig. 14 is a fragmentary vertical sectional view corresponding to part of Fig. 13 but showing one of the records being pushed off of the supporting shoulder on the spindle;

Fig. 15 is a view corresponding to Fig. 14, but showing the played records being lifted ofi" of the spindle; and

Fig. 16 is a view corresponding to Fig. 14, but showing a modification of the invention for nesses. e

Although the law requires a full and exact description, such as that which follows, of at least one form of the invention it is, of course, the purpose of a patent to cover eachnew inventive concept therein no matter how it may later be disguised by variations in former additions of further improvements; and the appended claims are intended to accomplish this purpose by particularly pointing out the parts, improvements, or combinations in which the inventive concepts arejfound.

In the illustrated form the invention includes a platform 25 having a circular depression 2'! within which is located a turntable 28 driven by friction drive wheel 30 which in turn is driven by a collar}! on a motor32, v As seen in Fig. 3, the motor may be suspended below the platform 25. The motor and associated parts arepreferably carried by a separate plate 33, asseen in Fig. 5, to permit their removal as an assembly. Drive wheel 38 is carried by a floating plate 3 3 which is spring urged in a. direction to wedge the drive wheel 30 between collar 3| and the flange of turntable 23. V 7 v The turntable 28 rests on a gear and bearing member 35 (Fig. 13) which rotates about a stationary bushing 36 whichprojects upwardly from a bearingblock 31, a bearing washer 38 preferably being interposed between the bearing block 31 and the thrust hub 39 of gear and caring member 35.

Spindle A stationary spindle ii extends downwardly through bushing 36 and through a bottom plate =32 with which it has a non-circular interlock fit to prevent turning of the spindle. A cotter pin it normally prevents removal of the spindle ii. One of the advantages of the present invention is that records and even the turntable can be removed without removing the spindle, even though the spindle is provided with a latch which contributes to the thoroughly reliable sequential dropping of the records. 7

As seen in Fig. 13, the records yetto-be dropped rest on a shoulder 46 of the spindle which preferably is curved to the shape shown. The edge of the lower record rests on one shelf 4'5 of an elongated pusher or push-off plate 48 at the lower edge of the slightly tilted records. If desired therecords may be held "against the shelf 4'! by a conventional light pivoted weight not shown. The push-off plate 48 is moved inwardly so that a push-off shoulder 49 rising from the shelf :3! pushes the lower record R off of the spindle shoulder 46 so that the record drops down along the spindle, the pusher shelf 4'! immediately being retracted out of the way- For dependability of feeding only one record, it is desirable that the second record R. be restrained against being moved with the" bottom record R due to friction between the two.

According to the present invention, therecord R is reliably restrained by a latchl which, however, oifers ino materialiopposition to the upward movement ofthe records when they have been played. 'The latch 5! slides within a slot 52 the spindle,'being restrained and guided therein by a'pin 53 whichextends through a slot 54 in the latch 5|. A record which bears against the side face .55 of the latch will be effectively restrained against lateral movement since no amount of lateral pressure against this side face will displace.the latch. However, in

thecase of lifting fromtheturntab-le the records which have been played, the upwardly moving record will strike the bottom face El of the latch 5% with the result that the latch will readily yield upwardly to the position shown in Fig. 15, so that the records may freely pass upwardly past the latch. The shaping of the slot is such as to serve as a cam to swing the latch to a position within the body of the spindle.

To prevent damage to the bottom record of a stack dropping onto the spindle shoulder 46, when a previous bottom record has just been released therefrom, re'siliencyis preferably providedin the path of transmitting the shock load. For. this purpose, the. spin'dle'with itsjnormal load is supported by spring'55, which yields upon the impact to allow the spindleto'move downward slightly.

Intermix-ed records of different thicknesses From, Fig. 14, it will be seen that ifrecords'of only half the thickness ofv those shown were 'played two records might slide underthe latch 5i. Of course if only such thin records were to be played, the latch 5! could be redesigned to extend down far enough to let only one thin record pass thereunder. If that were the case, however, the thick record would not get under the latch 5i. I

Sometimes it is very'desirable to 'intermix thin and thick records. The spindle of Figs. l3 to 15 lends itself readily, to solving this problem engaging it to restrain this record if it is not being directlypushed by the push-off shoulder When the lower record R is a thin record, the secondrecord B. may initially strike the latch 5! on its lower face 5i but it will, nevertheless, be restrained by the latch 5!. It will be understood that it does not take much force to restrain the second record R because if there are several records on top of it so as to produce considerable friction between it and the; bottom record R, these upper records will also produce friction on the upper surface of the second record R helping to restrain it. To ensure sufficient resistance even when there are burrs or the like tending to slide thesecond record, a fine rspring Bl! may be provided urging the latch 51 shoulder 49 should be slightly less than the thickness of a thin record so that it will never strike the upper of two thin records.

Push-017 host The push-offhead or plate 48 is part of apushoifpost assembly seen best in Fig. 2. This post comprises a sleeve 6! mounted fast on a rod 62 which extends downwardly through a flange 63 and a base 64 of a bell crank lever 65. The pushofi plate 48 is carried fast at the upper end of the post sleeve 61. As seen in Fig. 13, the bell crank lever 65 is pivoted by a pin 66 to a bracket 9i carried by the bottom plate 42; thus the entire push-01f assembly is pivoted on the pin 66.

The assembly is urged toward the position shown in Fig. 13 by a spring 68. A cam follower roller 69 (Fig. 2) is carried at the end of bell crank lever 65 to engage a cam track H on main control cam preferably in the form of cam disk 12 which at the proper time pivots the push-off post assembly to push a record R off of the spindle shoulder 46 on the spindle.

To accommodate records of different diameter the elongated push-off plate 48 extends further from the sleeve GI in one direction than the other and, when rotated with the sleeve BI, will present to the records either the push-off shoulder 49 at one end of the plate or a second push-off shoulder 49 rising from the shelf M at the opposite end of the plate. The plate 48 is held in the position to which it is turned by the force of a spring it through interaction of the sleeve BI with a cam collar I4.

Drive of control cam disk As previously indicated the turntable 28 is driven by the motor 32 and in turn drives gear 35 (Fig. 13). Gear 35 in turn meshes with pinion I6 which is fast on a shaft T1 to which a pinion 19 is also pinned. The pinion I8 meshes with a gear I9 which rotates freely on shaft or post 9|. The gear 19 carries a driving disk 92 which at appropriate times is drivingly engaged with the control cam disk 12.

The driving engagement or clutching is accomplished by means of a clutch dog 83 which, as seen best in Fig. 8, is pivotally carried at 83 by control cam disk 12 and is so balanced as to be biased toward the position shown in Fig. 8 in which the tip 84 of the dog 83 enters one of the notches 86 in the bottom of driving disk 82. The arrangement of these notches is seen best in Fig.7.

The clutch member or dog 83 is normally restrained from assuming the position shown in Fig. 8 by the tip 81 (Fig. 4) of trigger or cycle control plate 98, seen best in Fig. 12.

The trigger 89 is pivoted on a post 99 and it is shaped with a downward extension 9i having a Actuation of clutch dog Since the driving disk 82 is rotating constantly,

it follows that immediately upon removal of the trigger 88 from above the tip 84 of the dog 83, the tip 84 will enter a notch 86, thereby engaging the control cam disk 12 to the driving disk 82 so that the control cam disk starts to rotate. At the end of one revolution the dog 83 will pass under the tip 8'! of trigger 98 which will tilt the dog back to the position shown in Fig. 3 so that the driving engagement through the dog 83 will be broken and the control cam disk 12 will cease rotating. Its position of rest will be determined by the coaction between the cam follower roller 69 and a shallow depression 94, seen in Fig. 6. The control disk will remain stationary until the trigger 88 is again removed from dog 83.

The trigger 88 may be moved manually by operation of manual control lever 96 or automatically by tone arm 9'1.

Automatic operation According to conventional practice, the record changing cycle is initiated at the end of the playing of one record by the more rapid swinging of the tone arm as a result of the special shaping of the needle track on the record. The tone arm 9? is mounted on a tone arm spindle 99 (Fig. 9) which rotates as the tone arm swings. Pivotal'ly mounted on the tone arm spindle 98 is a. trip finger 99. This trip finger rests on the peripheral rim of a bushing Ifll fast on the tone arm spindle 98 and is pressed against the bushing with a predetermined pressure by a weak spring I92.

As the tone arm 97 approaches the end of the record, the trip finger 99 moves slowly against a trip lug I93 (Figs. 3 and 4) turned down from trigger B8. Continued movement of the tone arm pivots the trigger 88 slowly in a direction to swing its tip 31 from above the clutch dog 83. While the needle is in the playing portion of the needle groove of the record, however, the trigger 88 never completes the tripping movement, because it is frequently kicked back to its starting position by return lugs I94 on driving disk 82, which strike a return flange I96 turned up from trigger 98.

The spacing between the return lugs I94 is such that when the needle enters the steeper part of the needle groove after the playing portion of the groove, there will be time, with this increased speed of movement, for the trip finger 99 to swing the trigger 88 out from over the dog tip 8d of the dog 83 so as to release the dog to engage the driving disk 92.

Tone arm control According to conventional practice, but in a novel manner, the tone arm spindle 98 is so connected to the tone arm that raising the spindle will raise the tone arm from the record, and rotating the spindle will swing the tone arm. According to the present invention, both of these movements are controlled by a single groove on the control cam disk "I2. A disk I98 is rigidly carried by the tone arm spindle 98 and in fact may be integral with the bushing IUI. The disk I93 is provided With a depending skirt IIII9 having in its lower edge a notch III. A knife edge II2 carried by a lever II3 may be raised to engage the engagement surface on the bottom of the skirt I99 and raise the tone arm spindle 9B and hence the tone arm. The knife-edge II2 may be swung so that by friction or by engagement with notch I I I it will rotate the tone arm spindle 98, and hence, swing the tone arm. In order to accomplish this two-way movement of the knifeedge M2, the lever [I3 is doubly pivoted as seen best in Fig. 10. Pivoting about a horizontal axis is obtained by pin Iii which passes through the large flange H9 formed on lever H3 and through a bracket Ill. The full height of the flange IIS bears against the smooth face of the bracket II! for stability and a washer II8 may be positioned under the head of pin II4. If desired, the pin H4 may be in the form of a screw to facilitate a snug adjustment of the pivotal action of the lever H3, and the washer IIB may be resilient if desired. 7

The bracket II! is provided. with; upper; and lower flangesd I9..and:'I.-2 I;which are'pivoted to a. post .I 22ythus providingrpivoting.aboutavertical axis.

The lever I Iii-carries. a, cam.-follower.pin.-..|23 which is pressediby. spring IZA-zagainst the .under surface of control cam disk 12.: .Theham-iollower I 23 rides in a cam groove, I 260i control disk 72. The base of this groove (the axially facing wall) is shaped to press-the cam-followen I23-down wardlyat the proper time, thus raising the knifeedgel l2g which--in-=turn raises the tone-arm control=unitor--spindle unit (including-disk I68 and spindle=98 to raise the tone arm.

When thetonearmhas been raised,-one of the side walls oi the camgroove I 26' cooperates with the cam-followen pin. I23-to :pivot the-lever H3 aboutethe: post I22; thus swinging theknife-edge -I l Z-Which in turn swings the-tone arm.

Control for different recordsizes After. the: tonearmis swungout from cover. the recordwhich has been played vand another record has beendroppedthereon, thetone armjis swung into a .position. over the starting groove. over the new record.-.and..is lowered. .to setvthe needle on the starting-.groove-of. the record. The set-clown position. is, of courSe..-: difierent for the different sizes ofxrecord. Accordingtothe resent invention, the control iormonev set-down. position. or the. other is. provided; in an. exceptionally simple manner; by pressing the cam-followeppin. I23 againstthe outer wall .of cam groove IQiiior smaller. records. such. as. the common inch records and pressing-it. against .theinner wall of the .cam. groove I26. :for.largerecordssuch as .the commonlZinchrecords... The lever II tmay be biasedby leaf. spring I2lpt0 press .the. cam-fol lower pin I.2.3.z-in either direction.

The direction.lof biasrof. the leaf. spring.- I21 is controlled by turning the pusheofilpostsleeve BI as described under the heading Push-on post. The rods 62 (Figs. 2 and 13) rotates with the r push-off -p1ate 48L- East on the. bottom of therod :62 .is the collar I3I' carrying -acrank-arm I32; As-seen best in :Fig. 4, the crank arm I 32- is linked to leaf spring I2]. in any suitable' manner as by wire link I33. The l-inkshouldibe so-shaped as to be able either to push orpullthe leaf-spring I21." With-the .partsin position, as shown in Fig. 4; the link I331 would pull the spring I21 so as to-press the camefo'llower: pin l23-against the inner wall ofthecamgroove 125'. Withthecrank arm: J32. turned. in the opposite direction (by virtueof turningthe :push-ofi plate48-for smaller records), the :link I33Lwould pull the spring I255 so asuto press the cam-.iollowerxpin I23 against the outer wall .ofzcaxn-groove l The parts-mayme soconstructed as to permit the. turning of .the pusheoffa plate 48 .in either directionifrom .eitherqposition. In the illustrated .form. of .-.the .invention; however, ittis normally limited to 1l'80inmovement by stops I36 (Figs; 1

a and 3) carried; by theplatformiiand positioned to :engagea pin. it'lscarriedib'y thesleeve 5i.

Thus-it is seen thati-when the record. changing cycle starts; the base surface of the cam groove 25 pnshesuthe-cam follower pin I 23 downwardly toraise the knife-edge. H 2 and through it raise the tone arm.. Thereafter a side wall of the cam groove; I25 causesthecam=follower pin I23 to shift laterally thereby: swinging, the knife-edge I .I 2 horizontally: and thereby swinging the tone armto the position out-10f theway oftheerecord to be dropped. Then the camefollower; pin,,I2-'i at its top, a U-shaped bracket MI.

8, following the same.. sid'e.-' wall ofi lcam'u'grooverl 25; will swing the knife-edge H2; intheaopposite direction to move .thetone. arm .91 to the proper set-down: position depending. on the size .ofrecord being. played, and. for which .the'push-off plate .48. is adjusted.

Adjustment of set-down positions The spacing between the two set-.downpositions'is controlled quite accurately by the width of the cam groove IZtat the appropriate point and the diameter of the cam-followerpin (I23. These parts can beformedquite accurately in manufacture; so that thespacing between .twO set-down positions will be s-ufiiciently accurate; *Zowever, it is not practicalto make all-the associated parts with-such uniformity as toa-voidall adjustment of theset-down tonearm position;- With the spacing correct, one, adjustment will take care of both positions.

According to thepresent invention. this one ad-v justment can be made in the tone arm' itself or at the head of the tone arm spindle so that the ad-. justing screw is readily accessible and the posi+ tion of the tone arm can beobserved while the adjustment is being made. The mounting of. the tone arm which. provides this adjustment is best seen in Figs. 9 and 11.

The tone arm spindle .,98,.carries..fast: thereon, To; this bracket is pivoted'an inverted U-shaped bracket I42; The legs of:this.braoket.. I42 are resilient .to permit its removalirom bracket I4:I,:the pivots beingstub pins carried by-either bracket. 'The invertedbracket: I 425. has a hookzlflfrigidly-secured thereto, the upper. portion I of. which forms a base plate I4 3. The tone arm .9'llhas a mount:- ing plate M8 pivotally secured to the base. plate I44 as by a rivet I41. The angular positionof the mounting plate I 46 onthe base plate I .44 is determined by an eccentric pirrI lB whichiseccentricallypivoted inbaseplate I44; The; pin I48 is provided: with a screw-driverslotto which access may behad throughahole I49. in thetone armB'I. Turning the'pin lllflywillvsimultaneously adjust both positions of the tone arm 91.

A cleat I5I is formedyon-plate vHl land-extends through a slot I52, being turneddownato. bear against the upper surface. of mounting plateal 46 to hold the mounting plate, firmly: against. base plate I44.

The mounting plate I46 is preferablyfmounted on-the tone armv 9] by rubber grommets I154 'to stop the transmission of-vibrations;

A shield.- Ifit is desirably .yproVidGdTforr:ornar mental reasons andto protect the working parts from tampering.

A bracket I57 mounted on platformlfrextends into shield I 56 and'is positioned :to be engaged by hook I43 when the tone -arm spindlea98aisi raised. This operates to tilt the tone arm 911.?

When the tone arm swings in the raised position, the hookarm slides on the bracket I51.

When the needle is restingon the record; the hook" I 43, and the bracket I51. are -.out.of contact. Hence'the weight of the tone arm is carried. by the needle: and by the pivot pins..I 59b'y.which:the inverted bracket I42Iis pivoted to the bracket 1.51. The axis of these pivot pins preferably intersects the axis of the ,tone-arm spindle 98. Thus the tone arm spindle has-no lateral. thrustexerted uponitby the weightof the. tone =arm \vhenithe record is being played' This makes possiblea very simple and almost frictionless mounting'of the, tone armspindle 98.

The tone arm spindle 98 is pivoted at its upper end directly at the platform 25 and at its lower end by a fixed stirrup or bracket I BI which is ri idly secured to the bottom plate 42. During the play of a record, the platform 25 and stirrup I6I merely serve as guides for the shaft 93, exerting substantially no thrust thereon.

At its lower end, the spindle 98 is conically shaped and its point rests on the bottom plate 42, the point forming a, pivot and being very slightly rounded in accordance with good pivot practice. Since the load is carried entirely by the small pivot the frictional torque is extremely low.

Manual control lever As seen best in Fig. 4, the manual control lever 96 is slidably and pivotally mounted on the underside of the platform 25 by means of a slot I63 in lever 96 through which a pin I64 extends. The outer end of the control lever 96 carries a knob I66 (Fig. l) which projects upwardly through a T-shaped slot I61 on the platform 25. The T- shaped slot I61 permits moving the knob I66 in three directions from an intermediate point.

When the knob I56 is at the right hand end of the slot I61 as viewed in Fig. l, the motor 32 is turned off. Moving the knob toward the center of the slot starts the motor. This is accomplished by a switch control lug I68, which, when the switch is off, lies between the arms of a switch lever I69 forming 'part of switch I1I. When the knob I66 is moved to the left from the right hand end of the slot I51, the lug I58 engages the right hand arm of switch lever I69 and actuates the switch to the on or closed position, thus starting the motor. When the knob I66 is moved to the right hand end of the slot I61, the lug I68 engages the left arm of the forked switch lever I69 and actuates the switch to the off position, stopping the motor.

Manual play For the manual play of records it is desirable to prevent the actuation of the cycle starting mechanism. This is accomplished by moving the knob I66 inwardly into the center leg of the slot I61. In Fig. 4 the manual control lever 99 is shown in the position which it then assumes. Here it is seen that an arm I12 of control lever 95 engages an upturned lug I13 on the trigger 98 thus preventing this trigger from being moved to the cycle-starting position.

Manual cycle-starting In the automatic play of records it is desirable to start the record changing cycle manually either for dropping the first record, or occasionally, for rejecting a record which has been started. This is accomplished by merely shifting the knob I66 to the extreme left in slot I61 and releasing it. The leftward shift brings a spring finger I14 which is carried by manual control lever 96 against the side of lug I13 on the trigger 88, thus actuating the trigger to the cycle-starting position. In other words it pivots the trigger 88 so as to draw the tip I31 thereof out from over the clutch dog 33, allowing the latter to engage the driving disk 82 to drive the control cam disk 12.

Further details The bottom plate 42 is supported from the platform '25 by posts Ill and 89 previously mentioned and such additional posts I15 and I11 as may be desired.

The post I11 serves as a stop for limiting the 10 movement of the tone arm, this post extending through a notch in the disk I98.

The post I11 also serves as a stop for the movement of the trip finger 99, this trip finger being provided with a lug I18 which engages the post. The lug I18 is so positioned that it will normally strike post I11 before the tone arm reaches the end of its outward movement. This positions the trip finger 99 with respect to the tone arm so that it will come to bear on the lug I63 at the proper time.

The trip arm 99 preferably does not engage the lug I03 until near the end of the record. This leaves the tone arm moving with entire freedom during most of the play of the record. One of the advantages of the present invention is the almost frictionless nature of the tone arm movement. The friction is so slight that if the needle is rested on a smooth surface on the turntable, near the periphery thereof, the slight torque exerted thereby about the tone-arm spindle will cause the tone arm to swing inwardly, if the turntable is rotated forwardly, and outwardly, if the turntable is rotated rearwardly. However, even after the trip finger 99 strikes the lug H13, the friction is extremely low since the trigger 88 is so light and well balanced as to offer very little inertia or resistance. The slight thrust of the clutch dog 83' on the trigger is parallel to the axis of rotation of the trigger so that the thrust does not directly oppose movement of the trigger or necessitate compensating rotative forces. It has been found possible to have the trigger consistently yield with a side pressure exerted by the record groove of less than {g the side pressure required by the methods of control heretofore commonly used.

General operation To play a series of records automatically, the records are slipped onto the spindle II and rested on the shoulder 35 thereof, the edge of the bottom record resting on the shelf 31 (or shelf 41*) of the push-off head 58. The control knob I65 is then shifted to the lefthand end of slot I62. This swings control lever 96 so that it trips the switch lever I69 to the on position to start the motor and moves spring finger I14 carried by the lever 96 against lug I13 of trigger 88, allowing clutch dog 83 to engage the main control cam disk 12 to the drive disk 82.

The control cam disk 1.2 tilts the lever I It: about a vertical axis and swings it about a horizontal axis to first raise and then swing the tone arm and then lower it to the starting position on the record. In the meantime the first record to be played has been dropped onto the turntable by being pushed off of the spindle shoulder 16 by the push-off head 68 which was actuated by cam disk 12 operating on bell crank lever 65. The set-down position of the tone arm 91 is determined according to the setting of the push-off head, 48 for large or small records. In one case the link I 33 pushes the spring I21 so that the cam follower. I23 bears on the outside wall of cam groove I25. .Both cam walls are preferably shaped to start and stop the tone arm smoothly.

At the end of the record changing cycle the dog 83 glides under the trigger 8B which disengages it so that the record changing parts come to rest.

After approximately each revolution of the turntable one of the return lugs Ill l presses the return finger I95 on trigger 88 and nudges it to 15 the position shown in Fig. 4, in which position it is -restraining the clutch 'dog 83 'from'assuming its engaging position. However, when the playing-of the recordhas been 'finishedand the needle runs into the steep portion of the needle groove at theend of the record, the resulting increased drive .the control cam disk 12 therewith, thus again starting the record-changing cycle of record-changing parts. "For manual play of a record, the records may be. placed manually on the turntable and the control knob 1E6 maybe moved to the central leg of the'T slot 857, thus locking the restraining plate 58 in. its'restraining position so that the recordchanging parts will not be actuated. The tone arm may then be placed on the record by hand. To turnoff the motor the control knob N56 is moved to the righthand end of slot [6]. The tone arm is lifted from the record by hand. The record or records may be removed by simply lifting them off of the turntable since the latch 51, which prevents the dropping of more than one record at a time by the push-off head, oifers'no resistance tothe removal of the records from the spindle.

Until the control knob N56 is moved to the end of .theslot Hi1, the last record will be played over and over, but if desired, automatic shut-off means may be provided.

I claim:

1. Tone arm swinging means for record-changing apparatus and the like including a tone arm, means for mounting the same to'permit the tone arm .to swing vertically and horizontally; a cam having a single cam groove forming inner and outer. walls, a follower in the groove, spring means to bias the follower optionally against the" inner orouter wallby setting another part of the apparatus for large or small records, and means controlled by the follower for swinging .thetone .arm to the proper set-down position for large .or small records.

2.. Tonearm swinging means for record-changing apparatus and the likeincluding a tone arm,

means for mounting the same to-permit the tone arm to swing vertically and horizontally,a cam having .a single cam groove forming inner and outer walls, .-a follower in the groove, a spring connected to the follower, means connected to the spring and .movable, in opposite directions to cause the spring. to bias the follower optionally againstjthe inner or outer wall,.and means controllediby the follower for swinging the tone arm to .the proper set-down position for large or small spindle to form two arms, one arm being engageable with the tone arm spindle unit for raising and lowering the spindle and for rotating the same, a camfollowercarried by the otherarm of the lever, and a cam having cam surfaces-arranged-to engagethe cam followerand positioned -';zforiswinging 'the'lever'ivertically and: horizontally to imp artrsaid movements to'thetone arm-spindle.

- 4. Arizona arm control apparatusEforautomatic record *changers and :the like, including :a' tone arm vspindle 'unit comprising a'vertical spindle :and'a tone arm pivoted to the spindleiforvertical movement on a1ho'rirontal axis, jmeans for -mounting the spindle for vertical axial and horizontal rotative movements, a leverfulcrumedintermediatelyofiits ends-on approximately vertical and horizontal pivots at a point spaced from the said spindle to form two arms, one ofthe arms being engageable with the tonexarm'unit for raising and lowering the spindle and for rotating the same, a cam follower carried by the other :arm of the lever,:a cam havin'gtcam surfaces 'arranged toengage the cam follower and positioned for swinging-the lever vertically and horizontally 'to impart said movements to the 'tone 'arm spin- :dle, andimeans located in the path of the-tone :arm andenga'geable'with the-same for swinging theitone arm upwardly when the spindle'israised'. 5. Atone arm'control apparatus forsautomatic record changers and the like, including awtone arm spindle unit comprising a vertical spindle, :a tone arm mounted on the'spindlasmeansfor mounting the spindle for vertical axial and horizontalrotative movements, a lever fulcrumed'intermediately: of its'ends on approximately vertical and horizontal pivots'at a point spaced from the spindleto'form; two arms-one of thearms being radially spaced from the spindle and having a portion engaging the tone arm spindle unit and movable to-rotate the: same and alsdforraising and lowering the spindle, a-cam follower carried by the-other arm of the lever, and a cam having surfaces arranged-to engage thecamfollower'and .positioned for swinging the lever vertically and horizontallyto'impart said movements-tothetone arm spindle. 7

6. A. tone arm control apparatus for automatic record changers and the like, including a tone armspindleunit comprising a vertical-spindle and'a tone arm'pivotally mounted on the spindle for vertical movement ona horizontal axis; means for mounting the. spindle for axial and 'rotative :rnovements, a lever. fulcrumed' intermediately of its' ends-xon'approximately vertical and horizontal 'pivotsat'apoint spaced from the spindleto form two arms, one of the. arms having a portionvradia-llyspaced from the spindle and -engageable with the tone arm spindle unit -forrraising and lowering the spindle and for rotating the same. a cam follower carried by the other arm of the lever, ,a.camhaving .cam surfacesarrangedto engage the cam follower and .positionedfor swinging saidlever vertically andrhorizontally to impart said movements to the tone arm spindle, and means located in the path of the tone arm and engageable with the same for swinging the tone arm upwardly on the spindle when the spindle is raised.

7; Atone arm controlapparatusfor automatic record changers and the like, including a tone arm spindle unit comprising a vertical spindle and a tone arm mounted on the spindle,.means for mounting the. spindle for axial and rotative movements, a lever'fulcrumed intermediatelyof its ends on approximately vertical and horizontal pivots at a point: spaced from the spindle to form two arms, one of the arms being engageable with the tone arm spindleunit and movable verticallyand horizontally for raising and"lower-' ing the spindle and for rotating the same, acam follower carried by the other armof the lever, and a cam-including a :cam track'consistingof a single continuous groove receiving the cam follower and having inner and outer walls presenting cam surfaces for engaging the follower for swinging the lever horizontally in opposite directions, said cam track also including a bottom cam surface for engaging the cam follower for swinging the lever vertically to raise and lower the spindle.

8. A tone arm control apparatus for automatic record changers and the like, including a tone arm spindle unit comprising a vertical spindle and a tone arm mounted on the spindle, means for mounting the spindle for axial and rotative movements, a lever fulcrumed intermediately of its ends on approximately vertical and horizontal pivots at a point spaced from the spindle to form two arms, one of the arms being engageable with the tone arm spindle unit for raising and lowering the spindle and for rotating the same, a cam follower carried by the other arm of the lever, and a cam having a cam track consisting of a single continuous groove including variations in two transverse directions, the variations in one direction moving the cam follower and said lever in a direction to raise and lower the spindle and the other variations moving the cam follower and the lever in a direction to rotate the spindle for swinging the tone arm horizontally in opposite directions.

9. A tone arm control apparatus for automatic record changers and the like, including a tone arm spindle unit comprising a vertical spindle and a tone arm pivotally mounted on the spindle for vertical movement on a horizontal axis, means for mounting the spindle for axial and rotative movements, a lever fulcrumed intermediately of its ends on approximately vertical and horizontal pivots at a point spaced from the spindle to form two arms, one of the arms being engageable with the tone arm spindle unit for raising and lowering the spindle and for rotating the same, a cam follower carried by the other arm of the lever, a cam having a cam track consisting of a single continuous groove including variations in two transverse directions, the variations in one direction moving the cam follower and the lever in a direction to raise and lower the spindle and the other variations moving the cam follower and the lever in a direction to rotate the spindle and swing the tone arm horizontally in opposite directions, and means located in the path of the tone arm and engageable with the same for swinging the tone arm upwardly on the spindle when the spindle is raised.

10. A tone arm control apparatus for automatic record changers and the like, including a tone arm spindle unit comprising a vertical spindle and a tone arm mounted on the spindle, means for mounting the spindle for axial and rotative movements, a lever fulcrumed intermediately of its ends on approximately vertical and horizontal pivots at a point spaced from said spindle to form two arms, one of the arms being engageable with the tone arm spindle unit for raising and lowering the spindle and for rotating the same, a cam follower carried by the other arm of the lever, and a cam having cam surfaces arranged to engage the cam follower and positioned for imparting said movements to the lever.

11. A tone arm control apparatus for automatic record changers and the like, including a tone arm spindle unit comprising a vertical spindle and a tone arm mounted on the spindle, means for mounting the spindle for axial and rotative movements, 2. horizontal disc mounted on the spindle and having a peripheral edge radially spaced from the spindle and provided with a notch, a lever fulcrumed intermediately of its ends on approximately vertical and horizontal pivots at a point spaced from said spindle to form two arms, one of the arms being engageable with the horizontal disc and with the notch thereof for raising and lowering the spindle and for rotating the same, a cam follower carried by the other arm of the lever, and a cam having cam faces arranged to engage the follower and positioned to impart to the lever said vertical and horizontal movements for actuating said disc.

12. A tone arm control apparatus for automatic record changers and the like, including a tone arm spindle unit comprising a vertical spindle, and a tone arm mounted on the spindle, means for mounting the spindle for axial and rotative movements, a lever fulcrumed intermediately of its ends on approximately vertical and horizontal pivots at a point spaced from the spindle to form two arms, one of the arms being engageable with the tone arm spindle unit for raising and lowering the spindle and for rotating the same, a cam follower carried by the other arm of the lever, a cam having a single continuous cam groove receiving the follower and forming inner and outer walls provided with variations for moving the follower and for rotating the spindle and the lever for swinging the tone arm horizontally, said groove being also provided with a cam surface for engaging the follower to swing the lever vertically and raise and lower the spindle, and means to bias the follower optionally against the outer or inner wall of the cam groove for large or small records.

13. A tone arm control apparatus for automatic record changers and the like, including a tone arm spindle unit comprising a vertical spindle, a bracket pivoted to the spindle for swinging movement on a horizontal axis, a tone arm carried by the bracket and pivoted to the same for transverse pivotal adjustment with respect to the bracket, and an eccentric device mounted on the bracket and engaging the tone arm for adjusting the tone arm laterally with respect to the bracket and for securing the tone arm in its adjustment.

COLIN B. DALE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,847,400 Kincannon Mar. 1,1932 1,970,691 Collison et a1 Aug. 21, 1934 2,082,261 Runyan June 1,1937 2,235,693 Wells Mar. 18, 1941 2,287,726 Cranmer June 23, 1942 2,339,981 Cranmer et al Jan. 25, 1944 2,352,331 Leline June 27, 1944 2,374,080 Dale Apr. 17, 1945 2,387,916 Knox et al Oct. 30,. 1945 2,402,150 Dale June 18, 1946 FOREIGN PATENTS Number Country Date 176,397 Great Britain Feb. 28, 1922 399,172 Great Britain Sept. 25, 1933 588,675 Germany Nov. 23, 1933 166,534 Switzerland Mar. 16, 1934 477,325 Great Britain Dec. 24, 1937

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