US2488260A - Tone arm control for records of different diameters - Google Patents

Description

Nov. 15, 1949 E. ASCOLJ 2,488,260

TONE ARM CONTROL FOR RECORDS OF DIFFERENT DIAMETERS Filed June 17, 1946 //1/l EJV Toe,

' 5/3 20 fisczu Patented Nov. 15, 1949 TONE ARM CONTROL FOR RECORDS OF DIFFERENT DIAMETERS Enzo Ascoli, Sainte-Croix, Switzerland, assignor (Paillard A. G., Paillard to Paillard S. A. Limited) Application June 17, 1946, Serial No. 677,246 In Switzerland March 21, 1946 '7 Claims. 1

In talking machines provided with a mechanism for changing discs automatically, the arm of the pick-up is actuated, after the audition of a disc, by actuating members producing its vertical and horizontal movements according to a determined cycle. The various phases of this cycle are:

1. Lifting of the arm of the pick-up.

2. Pivoting of the arm of the pick-up about a vertical axis in order to withdraw it from the path traversed by a disc falling on to the turntable.

3. Pivoting of the arm about a vertical axis in the opposite direction for bringing the needle of the pick-up above the start of the disc to be played.

4. Lowering of the arm of the pick-up.

It will be evident that the amplitude of the stroke of entry of the arm (movement mentioned under Number 3) is a function of the diameter of the disc to be played and must be defined very exactly in order to avoid deterioration of the disc or of the pick-up.

In fact if this stroke is too large the needle of the pick-up comes, during the lowering of the arm, into contact with the part of the disc carrying the record and the start of this is lost for the listener. On the contrary when this stroke is too short, the needle of the pick-up may escape the outer edge of the disc which is liable to cause a deterioration of the pick-up.

In known devices for controlling the cycle of movements of the arm of the pick-up, the actuating member producing the entry of the arm is generally formed by a cam on which slides a pusher connected mechanically to the pick-up arm. It will be evident that the angular stopping position of the pick-up, which is a function of the lift of the pusher produced by the cam, is subjected to unsettled actions due to clearances and inaccuracies in mounting of the various members which connect the said pusher mechanically to the pick-up arm. But the inaccuracy which may be tolerated for the angular position of the arm is extremely restricted as the diameter of the recorded portion is variable from one disc to another and the external diameter of the disc also varies from one disc to another. It thus follows that known devices require 1. Very great precision in the parts connecting the control cam to the pick-up arm.

2. Efiecting adjustments in the mounting for 2 adjusting the angular stopping position of the arm.

Finally, after a predetermined duration of operation, as the clearances increase the precision of the position of the arm is no longer ensured.

My invention has for its subject a device for controlling the movements of the pick-up arm of a talking machine having a disc turntable and provided with a mechanism for changing the discs automatically.

This device is distinguished from known devices by the fact that it is provided with a member pivoting about a vertical shaft connected mechanically to the pick-up arm, this member co-operating with two actuating members pivoted co-axially to the latter and of which the first, connected mechanically to a member for controlling the horizontal movements of the arm carrying the pick-up, acts against the action of the second of these members which is subjected to the action of a spring tending to move the pick-up arm in the direction of the centre of the disc turntable, a stop, adjustable in position, being provided for defining the angular stop position of the said second actuating member and thus producing the stopping of the movement of the pick-up arm in an angular position corresponding with the beginning of a disc to be played resting on the disc turntable.

Another object of my invention concerns, in combination with a pick-up arm of a talking machine having a disc turntable and mechanism for changing discs automatically, a device for controlling the movements of said pick-up arm comprising a member pivoting about a vertical axis and connected mechanically to said pick-up arm, two actuating members pivoted co-axially with said first member, said actuating members cooperating with said first member, a second member adapted to control the movements of said pick-up arm, said second member being connected mechanically to one of said actuating members, means for applying a torque to the other of said actuating members tending to move said pick-up arm in the direction of the centre of the said disc turntable, the first of said actuating members being moved against the action of the second of said actuating members, and an adjustable stop, said stop being adapted to define the angular stopping position of said second actuating meme cam on the first of said actuating members, and;

transmission members between said cam and said pick-up arm, said cam and transmission members serving to produce the vertical movements of said pick-up arm, a sleeve moving about a" vertical axis, said actuating members being pivotally mounted on said sleeve, said transmission members including a pivotally mounted bell crank lever, a pusher passing freely throughzsai'clgsleeve.

and a supporting member at the upper end of said pusher, one arm of said bell crank lever" co-operating with said cam and the other arm of said bearing member ongsa-idpick-uprarmsaid bear-- ing member co-operating with said supporting member, said bearing member and said supportingmember being; so: arranged relatively to the vertical pivotalaxis of said. pick-up armand theirnature and size are so selected as to create. a fric.-- tion resistance torque which is sufiicient to'oppose relative movement between said bearing and sup-- porting members underthe action of a torque created'by the inertia of the said pick-up arm when its horizontal movement-ceases and by reason of the weight of the said pick-uparm' when the-pivotal axis-ofi the latter is out of the'vertical.

One form'of construction of. the' device forming the subject of my invention is shown in perspective viewdiagrammatically and by way of example: the: accompanying drawing, wherein:

Fig. 1- isa perspective view of the-device, the members ofthe latter being inthe normal position, that is to say inthepositionwhich they cupy during the-audition: of a disc.

Fig. 2 is a perspective view of the device, the members ofthe latter being shown inthe'position whichthey occupy at themoment ofreversing the-horizontal oscillatorymovement of ti e pickup-arm;

In the formof construction shown, the arm. I of the pickup is'hinged toahorizontal shaft 2. The latter iscarriedabya support 3 securedto a sleeve t turning in a bearing (not shown) provided' inthe framework ofthe talking machine. The: sleeve 4 turns about'a vertical axis and carries a crank 6 of which the pinlis subjected to the action of two actuating members 8 and 9 pivoted freely on the sleeve 5. The; first 8 of these members is connected mechanically by a link; l-llr to amember for controlling the movementsofthe pick-up-arm. The control member isrformedby'a disc" H- carrying a'pin l2 and driven by ashaft l6: Thelatter is set in'rotat-ion at the end: of the audition of a disc-for the duration of' the cycle of operations necessary for changing a disc by'known means not shown. The complete cycle of operations is controlled during a single completerevolution of the shaft 56.

The. second actuating'member's is subjected to the action ofaspring'ls which tends toproduce amovement: of the Y pick-up arm in the direction of-zth-ecentre of: the disc turntable (not shown). The secondfactuating'member9 carries a pin I4 adapted: to; cor-operate with" a stop It; adjustable in position, so as to define the angular stopping position of the arm for which the needle of the pick-up is located above the beginning of the disc to be played located on the disc turntable.

The stop I5 is formed by a plate having three notches l1, l8, l9 and secured rigidly to a shaft 5 pivoted in the framework of the talking machine. To this shaft is also secured an actuating member (not shown) enabling one of the three notches to be brought into the pathv of the pin it. The notch ll defines the position. of" the actuating member 9 for which the pick-up arm is located above a standard rest support (not shown). The notch l3 defines a position of the member 9 for which'theneedleof the pick-up is located above the-beginning of a disc of large diameter placed on the disc turntable. Finally the notch l9 defines a positionjot, the member 9 for which the needle of ther-pickup is located above the beginningof a discof small diameter placed on the 'disctur'ntable. The operating member, secured to the shaft 5 may be actuated either manually or automatically by a known feeler device which detects the diameter ofi a disc to be played.

The'verticalamovements of the pick-up arm are controlled by a cam- Z l on the actuating member. 8-. A roller 22. pivoted; to the end of one of the armsofa lever 23-oscillating on a: shaft, co-oper-- ates with the'profile of the cam-'21. The second, arm of'theilever: 23 acts on a; pusher 25 sliding; in the interior of the sleeve 4 and passing completely therethrough-.. To: the upper end' of the pusher emerging from the-sleeve 4; is securedan arm 25 having a bentv nose 2 and on which rests the arm I carrying the pick-up" by means of a bearing surface 20;. A lug; 28; secured to the pusher 25 and provided withan openingZQ-With rotation of the shaft l5 for the duration of the complete cycle of operations necessary for theautomatic changing of a 'disc'.

Of thiscycle of operation only the movements imparted to the pickup'willbe described here-- inatter.

The shaft l-6-being inrotation in the direction ofthe arrow'A,.the pin lZ-whichoccupies theposition shown in Fig. 1 (-stopposition during the audition of. a disc) 'moves'up to the diametrically opposite position; shown in. Fig. 2. During this movement the link. I-U- actuates the member 8 and the cam 2+ in'a counter-clockwise direction from the position shown-in Fig; 1. The ramp of the cam 2-! produces the'lifting of the pickup: arm by means of the oscillating. lever 23- and the pusher 25: During the operation the angular position of the. arm l relatively to its pivotal axis" with'the pin 1* and repels the latter, thusproduc-' ing a pivoting of the arm=carrying the pick-up on' itsvertical axis in acounterclockwise direction and moving the: pick-up away from the axis of rotation-of the disc turntable. During this-angular movement, the pin I comes into contact with the actuating member 9 and repels it against the action of its spring I3. The amplitude of the angular movement of the actuating member 8 is determined by the radius of the circle on which the pin I2 moves. When the latter is in the position shown in Fig. 2, the pick-up is disengaged completely from the disc placed on the disc turntable, that is to say that it is out of the path traversed by a disc falling on to the disc turntable. As the shaft I6 continues its rotation, the link I is moved in the reverse direction and actuates the member 8 and the cam 2! in a clockwise direction. As the whole part a of the cam 2| is circular, the pick-up arm remains in its raised position during the whole of the first part of its angular movement. On the contrary as the member 8 is retracted, the spring I3 expands and moves angularly the member 9 which actuates the pin 1 and holds it in engagement with the member 8. When the pin I4 comes into engagement with one of the notches of the stop I5, the actuation of the sleeve 4, by the member 9, ceases and the member 8, alone continuing its movement, leaves and completely releases the pin 1 from its mechanical connection connecting it to the member for controlling the horizontal movements of the arm I. When finally the roller '22 reaches the non-circular part b of the cam 2I,

the lever 23 oscillates on its axis 24. The pickup arm is lowered under the action of gravity whilst repelling the pusher 25. When the needle (not shown) of the pick-up comes into contact with the surface of .the disc to be played placed on the disc turntable, the pusher 25 continuing its movement under the influence of gravity, the nose 2? moves away from the pick-up arm so that the mechanical connection, connecting this to its member for controlling its vertical movements, is

interrupted. From this moment the pick-up arm is thus entirely free and the pick-up can follow the movements imparted thereto by the track traced on the disc.

From the foregoing it will be seen that the amplitude of the incoming stroke of the pick-up arm and its angular stop position above the beginning of the disc to be played, is exactly defined by the stop I5. This position is maintained during the lowering of the arm by reason of the resistance torque produced by the friction between the bearing surface 20 secured to the arm I and that of the nose 21. It is possible to select the nature of its surfaces, their dimensions and their arrangements relatively to the vertical pivotal axis of the arm I, in such a manner that the resisting torque is sufficient for opposing the forces of inertia and balancing the arm when the pivotal axis of the latter is out of the vertical.

It will be understood that the members and elements of the device here described by way of example and with reference to the accompanying drawing may be replaced directly by their equivalents. For example it is possible, for reducing the torque necessary for producing the horizontal movements of the arm I, to cause the pusher 25 to pivot in synchronism with the arm I by securing the pin 39, for example, to the actuating member 9. As the latter is in contact with the stop I5 during the lowering of the arm I it defines the angular position of the nose ZI during this movement of the arm So that the angular position of the latter is held by the resisting torque which is opposed by the friction of the bearing surface 20 of the arm I resting on the nose 21 against all relative movements between the latter and the arm I. V v

In spite of its great simplicity the device described allows of obtaining a precise control of the movements of the pick-up arm and further has the advantage of defining in a very precise manner the angular position which the pick-up arm should occupy so that the needle of this comes into contact with the beginning of the disc to be played placed on the disc turntable.

The necessary torque for causing the pick-up to enter is no longer furnished by the expansion of the spring I3 but by the said friction clutch. In this modified form of construction the operation of the device is similar to that described with reference to the accompanying diagrammatic drawing, the pick-up arm being also subjected to a torque tending to move it towards the centre of the disc turntable.

I claim:

1. In a talking machine having a disc turntable and a mechanism for changing the disc automatically, the combination with a pickup arm, of a device comprising, means supporting the pickup arm in a. horizontal position and providing a horizontal pivot for the pickup arm to permit same to swing upwardly and mounted for rotation about a vertical axis, a crank rigid with the supporting means, a pair of actuating members rotatably mounted for engagement with the crank, one of the actuating members carrying a cam, a link connected at one end to the cam carrying actuating member, a control member rotatably mounted and pivotally connected to the other end of the link, yieldable means engaging the other of the actuating members and urging the free end of the pickup arm toward the center of the turntable, an adjustable stop rotatably mounted and engageable in three difierent positions with the other actuating member and thereby defining a corresponding number of limiting positions of the other actuating member, a member movable Vertically and in lowered position having its upper end disengaged from the pickup arm but in raised position frictionally engaging same to prevent relative rotation thereof, fixed means slidingly engaged by the vertically movable means to prevent rotation thereof, and means coacting with the cam of the first actuating means and operable thereby and engaging and lifting the vertically movable member to swing the pickup arm about its horizontal pivot.

2. The combination according to claim 1 and wherein the supporting means includes a sleeve receiving the vertically movable member.

3. The combination according to claim 1 and wherein the crank includes a pin engageable by the actuating members.

4. The combination according to claim 1 and wherein the control member includes a disc providing a pivot for the link.

5. The combination according to claim 1 and wherein the other actuating member is provided with a pin and the stop has three notches for the pm.

6. The combination according to claim 1 and wherein the vertically movable member is guided by the supporting means and carries at its upper end an arm having a bent nose engaging a bearing surface on the pickup arm.

'7. The combination according to claim 1 and wherein the lifting means is a bell crank.

ENZO ASCOLI.

(References on following page) iBE E E CE CITED T fol owin ve nces are of record in the file of this patent: :0,

UNITED 'ISTATES PATENTS 5 e Date gig gos 1,357,602 Welch z r v Nov. 2, 1.920 460,502 f 1,406,607 Brooks et a1. Feb. 14,1922 1,406,608 Brooks etnal Feb. 14, 1922 Name Date Wr gh -.-.-v--r---.--.- p 1, 1940 011m T-V-- N v. 25, 19

.FQREIGN :RATENTS Country Date Great Britain Aug. 22, 1929 Grea'tfBritain Jan. 28, 1937 Australia. Mar, 24,1944

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