Patent GB-632828-A (GB)
Title: Improvements in or relating to record changing mechanism for gramophones
IPC: G11B17/16
Filed: 1947-06-27
Abstract: 632,828. Automatic gramophones. FORTUNE, H. J., MORTIMER, E. W., and GARRARD ENGINEERING & MANUFACTURING CO., Ltd. June 27, 1947, No. 17002. [Class 40 (ii)] In a record-changing mechanism of the type in which records are supported at the centre on an offset position of a centre post and at the edge by a platform with displacing means, and the pick-up arm movements are controlled by a rotary cam device 10 having an interrupted gear-wheel 12 in which interruption the driving pinion 7 may idle while a record is being played, means are provided for moving the gear-wheel 12 into engagement with the pinion 7 comprising an impulse lever 14 which moves into contact with a pin 17 on said gear-wheel 12 when released from a cocked position in which it is held by a trip-lever 20, said trip-lever being released by a pick-up lever 22 when the stylus engages an eccentric or unidirectional run-out groove. The end 18 of the impulse lever 14 is held back, against the tension of a spring 16, prior to an automatic cycle by a detent 19 in the trip-lever 20 which is urged in a clockwise direction by a spring 21. When the stylus enters the run-out groove of the record the triplever 20 is moved counter-clockwise to release the impulse .lever 14 by means of a spring- loaded pawl 26 or roller 29 on the pick-up lever 22, according to whether the run-out groove is eccentric or unidirectional, respectively. The heel of the arm 15 of the impulse lever 14 then comes into contact with the pin 17 on the gearwheel 12 which is rotated a small amount and engages the driving pinion 7. The horizontal movements of the pick-up arm are controlled by the lever 54 having a roller 53 engaging the surfaces of a cam 51. At the conclusion of the automatic cycle when the stylus rests in the run-in groove of the next record, the pin 17 encounters the toe of the arm 15 of the impulse lever 14 and re-cocks said lever with the triplever 20. When the pin 17 has moved clear of the heel of the arm 15 the interruption in the gear-wheel 12 coincides with the position of the pinion 7 and rotation of the gear-wheel ceases. At this point the roller 53 rests on the part 15a of the cam 51. When a new automatic cycle is commenced and no records remain on the stack, an arm 72, Fig. 6, which normally rests on the surface of the uppermost record of the stack, is held downward by a spring 74 so that a lever 75 is lifted and, by means of a detent 76, retains the end of the lever 54 as the roller 53 passes over the raised part 51e of the cam 51 so that continued rotation brings the roller 53 on to the cam 52. As the roller 53 comes into contact with the raised part 52a, the pick-up arm is swung outwardly to its extreme position over the rest and lowered thereon, and the other end of lever 54 presses the end 58, Fig. 5 (not shown), of a lever 59 to release the switchretaining detent member 42, Fig. 4. To restart the machine after a new set of records has been placed in position, or when a single record is placed on the turntable, the starting lever 31 is moved clockwise, whereupon the switch lever 37 is re-cocked and the lever 35 moved to unlatch the impulse lever 14 from the trip-lever 20, and so initiate an automatic cycle. In a similar manner, operation of the starting lever 31 during playing of a record will initiate a fresh cycle, so that the next record, if any are left on the stack, is lowered for playing. The starting position of the stylus, according to whether 12 inch or 10 inch records are in use, is determined by the position of a lever 89, Fig. 11, pivotally mounted on the pick-up lever 22, the position of said lever 89 being determined by a hand lever 81, link 84, and a bell-crank 85 having a pin 86 which engages the surface 87 or 88 on the lever 89 according to whether 12 inch or 10 inch records, respectively, are being used. The pick-up arm is lifted and lowered by a cam surface on the underside of the gear-wheel 12, as illustrated in Figs. 1 and 9 (not shown).