Patent GB-672634-A (GB)
Title: Improvements in automatic phonograph record playing mechanisms
IPC: G11B17/14
Filed: 1950-03-30
Abstract: 672,634. Automatic gramophones. RADIO CORPORATION OF AMERICA. March 30, 1950. [March 31, 1949] No. 8011/50. Class 40 (ii). In an automatic gramophone, records, having an extra large centre aperture, are supported on a large diameter centre post which revolves with the turntable and houses retractable shelf and separator elements which perform a complete cycle of operations during one revolution of the .turntable, the turntable and the records being designed to rotate at an angular velocity of the order of 45 revolutions per minute. The shelf elements 57, Fig. 2, and separator elements 58 are controlled by geared planetary wheels 79 freely mounted on studs 81 and rotatable by means of a gear wheel 71 on a central shaft 76. The shelf elements 57 have square openings into which eccentric ends of the planetary wheels 79 project in order that the shelf elements 57 may be retracted, ample clearance being provided to allow the shelf elements to be forced back against the pressure of a spring 89 when records are being withdrawn from the centre post. The separator elements are eccentric in shape and are secured on the squared ends at the top of the planetary wheels 79. The shelf elements 57 and separator elements 58 are arranged such that when the shaft 76 is rotated relative to the centre post 62 the shelf elements are extended when the separator elements are retracted, and vice versa. The lower end of the shaft 76 is fitted with a star wheel 73, which may be engaged by the end 156, Fig. 9, of a spring loaded threearmed lever 151 pivoted at a point 37. During the playing of a record the star wheel is not engaged and the shaft 76 is free to rotate with the centre post 62 so that the planetary wheels 79 are not rotated on the studs 81. When the stylus enters the run-off groove of the record, a spring loaded lever 110, Figs. 12 and 13, on the ends of an arm 101 secured to the pick-up arm shaft pushes the turned down end 137, Fig. 9, of a trip member 134 pivoted about a point 135 so that the, trip member is rotated counterclockwise and an upstanding lug 148 thereon is moved into the path of a tripping boss 147 on the underside of the turntable. The trip member 134 is thereby rotated a further amount in the counterclockwise directtion, and a downwardly projecting pin 149 on the trip member engages the surface 150 of the lever 151 and rotates it clockwise so that a pin 38 thereon engages one end of a lever 105 whose opposite end engages a depending pin 104 on the pick-up arm and lifts the stylus from the record. At the same time, a cam follower 152 on the lever 151 is controlled by the cam surface 67. Further clockwise movement of the lever 151 is thereby effected, whereby the trip member 134 is restored to its original position by a projection 155, and the pick-up arm is swung outwardly by the engagement of a projection 118, on the lever 151, with a stud 115 on the arm 101. At the same time the end 156 of the lever 151 engages the star wheel 73, to arrest the movement of the shaft 76 and alternately retract the shelf and separator elements to release a record from the stack on to the turntable. The increasing radius of the cam surface 67 at this stage causes the lever 151 to move counterclockwise so that a spring loaded lever 117 is permitted to move the pick-up arm inwards by pressure on the stud 115 until the other end of the lever 117 is arrested by a stop 126 corresponding to the starting diameter of the records. Further rotation of the cam surface permits the lever 151. and lever 105 to rotate counterclockwise so that the pick-up is lowered on to the record, after which the follower 152 emerges from the gap in the cam surface 67 and the automatic cycle is completed. The automatic cycle may be initiated, when it is required to reject a record, by pressing a push-button 59 which moves a slide 140 to operate the trip member 134. During the automatic cycle the pick-up is muted by the closing of switch 159. Pressure of the stylus on the record is reduced by the use of a coiled tension spring 102 attached to the rear end of the pick-up arm. A dash pot 165, Fig. 11a (not shown), may also be provided coupled to one end of the lever 105 to provide a damping effect while the tone arm is being lifted or lowered. The turntable is driven by means of a friction gearing 48, 61 which effects driving connection between a motor shaft 47 and the inside of the rim 52 of the turntable.