Patent GB-976258-A (GB)
Title: Improvements relating to automatic record changing gramophones
Inventor: GRANBY PETER HUGH
IPC: G11B17/02
Filed: 1962-08-31
Abstract: 976, 258. Automatic record changing gramophones. MAGNAVOX ELECTRONICS CO. Ltd. May 22, 1963 [Aug. 31, 1962], No. 33557/62. Heading G5R. In an automatic record changing gramophone including a cam disc which is driven through one full revolution in each change cycle from a friction driving roller driven by the motor or the edge of the turntable and which controls the change mechanism, a follower roller carried by a linkage which also carries the friction driving roller, is spring urged against the periphery of the cam disc and upon completion of the change cycle enters a recess in the periphery, this movement rocking the linkage to move the friction roller out of engagement with the motor spindle or the turntable to disconnect the drive to the cam disc. Fig. 2 shows the mechanism during a change cycle while the cam disc 7 is driven by a follower gear wheel 13 which is driven from the motor spindle 3 through pulleys 9 and 11 and gear 12. The follower gear wheel 13 and the friction driving roller 8 are carried by the ends of bell crank levers 14 and 17 which are connected by a pivotal link 16 and spring biased in the direction of arrow 19. When the cam disc 7 completes one rotation the follower gear wheel 13 enters the recess 20 and rocks the linkage so that the friction driving roller 8 is moved out of engagement with the motor spindle 3. Just before the follower gear wheel 13 enters the recess 20 a downwardly projecting peg (not shown) on the cam disc 7 engages a plate (not shown) and forces the plate to move and compress a helically coiled compression spring. This peg just moves over a top dead centre position in which the spring is fully compressed as the follower gear enters the recess; the cam is therefore urged to continue rotating under the action of the compression spring but is prevented from doing so by the engagement of an upwardly projecting peg 21 on the cam disc engaging one end of the arm of a bell crank lever 22. When lever 22 is moved to the position shown in Fig. 2, the compression spring starts the rotation of cam disc 7 so moving the follower gear 13 out of the recess and causing engagement of the drive from the motor spindle 3. The lever 22 carries at one end a friction plate 24 which frictionally engages the base 1 with two frictional ends 25 and also has a raised circular portion 26 which carries a striker arm 32. As the pick-up arm 6 moves inwardly it causes movement of a rod 30 which rotates friction plate 24 and striker arm 32, Whilst the gramophone is playing a record the striker arm 32 only rotates slowly and a lug 33 carried by the turntable is able to push the striker arm away from it without moving the plate 24. When the needle enters the runout groove at the centre of the record, the pick-up arm moves inwards more rapidly, the striker arm 32 engages the lug 33 fully, and bell crank lever 22 is rotated to allow a change cycle to begin. During a complete revolution of the cam disc 7 the pick-up arm 6 is withdrawn, a new record is dropped on to the turntable, and the pickup head is lowered on to the outer edge of the new record.