US3516677A - Pickup-arm control in automatic record-playing devices - Google Patents

Pickup-arm control in automatic record-playing devices Download PDF

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Publication number
US3516677A
US3516677A US743518A US3516677DA US3516677A US 3516677 A US3516677 A US 3516677A US 743518 A US743518 A US 743518A US 3516677D A US3516677D A US 3516677DA US 3516677 A US3516677 A US 3516677A
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United States
Prior art keywords
pickup
pin
link
movement
arm
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Expired - Lifetime
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US743518A
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English (en)
Inventor
Edward Thomas Humby
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Plessey Co Ltd
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Plessey Co Ltd
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Publication date
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    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B3/00—Recording by mechanical cutting, deforming or pressing, e.g. of grooves or pits; Reproducing by mechanical sensing; Record carriers therefor
    • G11B3/02—Arrangements of heads
    • G11B3/08—Raising, lowering, traversing otherwise than for transducing, arresting, or holding-up heads against record carriers

Definitions

  • a fixed abutment stem and an edge-cam portion of the link co-operate to deect the link about its pivot to disengage the step of the first edge portion from the pin to stop the outward drive of the arm while permitting it to be moved further outwardly when the outwardly moving pickup arm reaches a predetermined position and to cause the step of the second edge portion to strike the pin and propel it, during the subsequent return stroke, in the direction producing inward movement of the arm, said lastmentioned step being so inclined to the direction of movement of the coupling pin as to be moved out of engagement with the pin by reaction forces when the pin is prevented from further movement in this direction, a further fixed abutment and a further edge-cam portion being provided for defiecting, at the end of the return stroke, the link to a position of readiness to re-engage the step of the first edge portion during the forward stroke of a subsequent record-changing cycle.
  • This invention relates to automatic record-changer mechanisms of the kind in which a cam member, arranged to perform a single revolution for each record-changing operation, is employed to produce for each revolution of the cam mem'ber a single reciprocatory movement of a drive plate or equivalent member (hereinafter called drive plate), to which a member participating in the inward and outward movement of the pickup arm, hereinafter called the pickup plate, is arranged, after the termination of the playing of a record, to be coupled during movement of the drive plate in one direction-after the pickup has been lifted from the record, for example by the co-operation of a cam surface on the drive plate with an arm-lifting pin-until the arm has moved clear of the area of the largest record for which the player is intended, and also during a part of the subsequent opposite movement of the drive plate so that after a lapse of time in which a new record is arranged to be deposited on the turntable and in appropriate cases has effected the selection of a stylusdeposi
  • the still raised pickup arm is moved towards the centre of Y the record turntable until the stylus depositing position determined by the selection has been reached, whereafter the coupling means permit continuation of the movement of the drive-plate without further movement of the arm.
  • the pickup stylus By the time the pickup stylus has been actually deposited Mice on the record, it should .be free to follow the record groove with a minimum of resistance.
  • the length of the slot was so chosen that, when at the end of the outward movement of the arm, the member movable with the arm struck an abutment provided for the purpose, the pin was forced into the narrow portion of the slot and became frictionally clamped therein due to the above-mentioned resilience.
  • this friction was suicient to move the arm inwardly until its inward movement was terminated by a selector stop determining the selected stylus-depositing position, whereafter further movement of the drive plate in the last-mentioned direction moved the link relative to the coupling pin, causing the latter to leave the narrow portion of the slot and enter a wider portion, in which it was free to move without appreciable resistance.
  • the present invention has for an object to provide an improved mechanism for coupling the pickup plate to the drive plate, which permits the frictional coupling causing outward movement of the pickup plate to be terminated and the frictional coupling causing inward movement of the pickup plate to be initiated without relying on a stop arresting the outward movement of the pickup arm.
  • a link for coupling the pickup plate to the drive plate is connected to the drive plate by a friction-loaded pivot connection and has a plurality of cam-edge portions facing opposite sides of its radial length including a first, and an oppositely facing second stop-like portion for respective co-operation with a pin or pins projecting from the pickup plate, the one portion during the first part of that stroke of the drive plate which serves to move the pickup arm clear of the turntable, and the other portion during the return stroke of the drive plate, a third steplike portion facing in the same direction as the first and arranged to co-operate with an abutment which is stationary, at least relative to a stationary plane perpendicular to the pivot axis of the link, to produce movement of the link about its frictional pivot connection to disengage said first step-like portion from its associated pin, and further cam-edge portions respectively co-operating with stationary abutments for guiding the first step into cooperation with its associated pin during the first
  • the pickup plate is coupled to the drive plate by a flat link provided with a plurality of edge-cam surfaces and connected to the drive plate by a pivot subject to controlled friction,.one of said edge-cam surfaces forming a first step against which during the outward movement of the pickup arm a pin or like abutment, hereinafter called pin, of the pickup plate rests, and another edge-cam surface forming a second step which co-operates with an effectively stationary abutment member in such manner as to produce, at a predetermined point of the outward movement of the pickup plate, pivotal movement of the link member about its frictional pivot in such manner as to cause the said first step to clear the said pin so that further movement of the drive plate in the same direction will produce no further outward movement of the pickup arm, and a further edge-cam surface of said link forming a third step, this third step being so arranged, and the link itself being so guided by a further edge cam surface and also cooperating with a stationary abutment member, that during the return movement
  • the rst and third step-cam surfaces are provided on opposite edges of an elongated opening in the link, and a single pin extending from the pickup plate is arranged to co-operate successively with the first and third step surfaces of the cam.
  • the cam surfaces forming the second step which produces disengagement of the first step from its associated pin, is arranged on the outer edge of the link at that side to which the rst step faces, and this second step preferably co-operates with an end portion of the arm-lifting pin. It will be appreciated that during the time of this co-operation the pickup arm is always lifted so that only a short end portion of the lifting pin is required to be clear for cooperation With said second step, while the remainder of the projecting length of the lifting pin may, for example, be encircled by a thrust spring ensuring contact of the end of the lifting pin with the lifting cam, which latter preferably forms part ofthe drive plate.
  • FIG. l illustrates one embodiment of the invention and is a somewhat diagrammatic underneath perspective view of the relevant parts of a record changer, in which the elements of the record changer mechanism not directly participating in the operation of the invention have been omitted in order to facilitate understanding of the invention, and
  • FIG. 2 is a plan view of a practical form of link plate.
  • a turntable 2 is accommodated in a depression of a record-changer base plate 1 and is rotatable about its axis 2n.
  • a so-called cycling cam 3 is arranged to perform a single revolution at the end of each playing cycle.
  • a so-called drive plate 4 is pivoted to the base plate for movement about a pivot axis 5 and is actuated, to perform a reciprocation for each revolution of the cycling cam, by a roller 6 which is rotatable about a pin 7 on the drive plate, and which co-operates with a track 3a of the cam 3.
  • a pickup arm 8 is movable jointly with a plate 10 which is arranged at the underside of the base plate and is hereinafter referred-to as pickup plate, about a pivot 9 in the base plate 1.
  • a circumferential portion of the pickup plate is formed with a number of sawteeth or stop 11, and a selector stop 12 is arranged to be automatically set in such manner by each record as it moves to the turntable as to render one or another of the teeth 11 effective to terminate the inward movement of the pickup arm 8 during the arm-positioning movement, according to the diameter of the record.
  • An arm-lifting pin 13 is slidably mounted in the base plate 1 at a short distance from the arm pivot axis 9, and the pickup plate 10 has an aperture 10a, through which the pin 13 passes to engage a face-cam portion 14 forming part of the drive plate 4 and having, in a known manner, a ramp 14a which, at the beginning of the stroke of the drive plate serving to move the pickup arm away from the turntable centre, causes the pin 13 and thus the arm 8 to be raised, while the remainder of the face-cam portion 14 is flat to maintain the arm in the raised position during both the outward and inward lateral swinging movements of the pickup arm, that is until the drive plate 4 during its return stroke approaches its illustrated position of rest, in which the pickup arm is free to follow the track of the record groove.
  • the pickup plate 10 In order to produce requisite inward and outward movements of the pickup arm in accordance with the movement of the drive plate 4, the pickup plate 10 carries a coupling pin 15 which projects into a shaped elongated aperture or slot 17 of a at coupling link 18.
  • This link which is also shown in FIG. 2, is carried by the drive plate 4, to which it is connected by a friction -pivot 19, 19a.
  • the edges of the slot 17, as well as the outer lateral edges of the link 18, are formed with cam portions for respective co-operation with the coupling pin 15, with the end portion of the arm-lifting pin 13, and with one or the other of two guide stems 20 and 21 in a manner which will now be described in more detail.
  • the position of the parts as illustrated in FIG. l approximately corresponds to the rest position of the mechanism, that is to say to the position it assumes during the actual play of the record, when the cam 3, and accordingly also the drive plate 4, is stationary with the pin 13 allowed by the cam portion 14 to assume its lowermost position and with the cam-following roller 6 resting, under the action on the drive plate 4 of a spring 22, on the apex of the track in the cycling cam 3.
  • the cycling cam is, in a known manner, coupled to the turntable to perfrom one revolution.
  • edge portion 23 of the coupling link Once the edge portion 23 of the coupling link has made contact with the stem 20, further movement of the drive plate in the same direction will cause this edge portion 23 to slide along the stem 20, thereby producing gradual clockwise pivotal movement of the link in the friction pivot 19.
  • the edge portion 23 and the opening 17 are so shaped and so arranged relative to each other that the resulting movement of the coupling link 18 will cause the pin 15 to strike a step-like surface portion 24 at the left-hand side of the slot 17, and the inclination of this portion to its direction of movement is so arranged that the surface portion 24 will act on the pin 15 to swing the pickup arm 8 outwardly away from the centre of the turntable.
  • step portion 25 at the left-hand edge of the link 18 comes into engagement with the circumference of the lifting pin 13. Since this pin is only movable in an up and down direction, it acts on the step portion 25 as a fixed abutment and will, in sliding along the step portion 25, cause the link 18 to swing sharply in a clockwise direction about the friction pivot 19. As a result its step-like surface portion 24 will move out of engagement with the coupling pin 15 of the pickup plate and thus terminate the outward movement of the pickup arm.
  • the disposition of the step 29 is such relative to the direction in which the pin 15 can move about the pivot 9, that the step 29 will carry the pin with it and thus Imove the pickup arm plate 10, to which the pin 15 is fixed, in an anti-clockwise position to move the pickup arm 18 towards the centre of the turntable until the appropriate pickup put-down position, selected by the stop 12, is reached and the stop 12 prevents the pickup plate 10 from further pivotal movement.
  • the pin 15 will then remain stationary, and the cam surface 29 will slide along the pin 15, moving the link 18 in an anti-clockwise direction about the pivot 19, 19a overcoming the friction of the latter, until the pin 15 reaches the inner end of the ⁇ step surface 29, where the shape of the opening 17 allows the link 18 to move into contact with the guide stem 21.
  • the guide stem 21 co-operates with an edge portion 30 of the coupling link 18 to return the link 18 to its illustrated position, in which the pin 15 is clear by appreciable distances from both edges of the opening 17, before the ramp 14a on portion 14 of the drive plate 4 reaches the lifting pin 13 to allow the pickup stylus to be deposited in the record groove. It will be seen that when this takes place, there is no mechanical connection between the pickup plate 10 and the coupling link 18; during the actual play of the record the pickup arm is therefore completely free to follow the record groove with a minimum of resistance.
  • the surfaces which cooperate with the pickup arm plate may be arranged at the outer edges of the coupling link, the two outer edges being arranged to co-operate respectively with two separate coupling pins.
  • either different portions of the outer surfaces, or edge surfaces of an opening in the coupling link may be employed to control the pivotal movement of the coupling link relative to the drive plate 4.
  • a single guide stem may be used to perform the function of both stems 20 and 21.
  • an automatic record-changer mechanism having a mounting structure provided with means for supporting a turntable for rotation about a vertical turntable axis, a cycling wheel arranged to perform a single revolution for each record-changing cycle, a drive plate coupled to the cycling wheel to perform, during each revolution of the wheel, a single reciprocatory pivotal movement about a vertical axis, a pickup arm mounted for horizontal inward and outward movement towards and away from the turntable axis and for vertical raising and lowering movement, a pickup plate mounted to participate in the inward and outward horizontal movement of the pickup arm, and arm-raising and lowering means operative to raise the pickup arm during an initial portion of the forward stroke of the drive plate, then maintaining it raised during the remainder of the forward stroke and an adjoining initial part of the return stroke, and allowing it to descend and remain lowered during a nal part of the return stroke of the drive plate: the combination comprising coupling-pin means on the pick-up arm plate, a coupling link for co-operation with said coupling-pin means, a pivot
  • An automatic record changer as claimed in claim 3 including a pickup-lifting pin guided in the mounting structure for up-and-down movement while being prevented from transverse movement, said pick-up-lifting pin being arranged to form abutment means for co-operation With References Cited Said rSt Cam-edge pOItOn. UNITED STATES PATENTS 5.
  • the coupling link is formed with a guideedge 3,243,188 3/1966 Caddy 274-10 th"t'l fh t d t th d' uS e H11 la Part 0 te Ouwar movemen of e rive 2,939,464 6/1960 Guest n 274-40 plate to keep said rst and second edge portions clear of the coupling pin means until said raising and lowering means have raised the arm from its playing position.

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US743518A 1967-07-14 1968-07-09 Pickup-arm control in automatic record-playing devices Expired - Lifetime US3516677A (en)

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Application Number Priority Date Filing Date Title
GB3257467 1967-07-14

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US3516677A true US3516677A (en) 1970-06-23

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GB (1) GB1227745A (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9741328B2 (en) * 2015-01-14 2017-08-22 Daniel J. Howington Apparatus for varying the pitch of audible tones driven by a turntable

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2939464A (en) * 1957-05-15 1960-06-07 Birmingham Sound Reproducers Sound reproducing apparatus
US3174754A (en) * 1960-12-23 1965-03-23 Zenith Radio Corp Tone arm brake assembly
US3189352A (en) * 1961-12-05 1965-06-15 Gen Electric Anti-skate device
US3243188A (en) * 1960-12-20 1966-03-29 Garrard Eng & Mfg Co Ltd Record changing mechanism

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2939464A (en) * 1957-05-15 1960-06-07 Birmingham Sound Reproducers Sound reproducing apparatus
US3243188A (en) * 1960-12-20 1966-03-29 Garrard Eng & Mfg Co Ltd Record changing mechanism
US3174754A (en) * 1960-12-23 1965-03-23 Zenith Radio Corp Tone arm brake assembly
US3189352A (en) * 1961-12-05 1965-06-15 Gen Electric Anti-skate device

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9741328B2 (en) * 2015-01-14 2017-08-22 Daniel J. Howington Apparatus for varying the pitch of audible tones driven by a turntable

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