Patent GB-1197839-A (GB)
Title: Improvements in or relating to Phonograph Record Player Mechanisms.
IPC: G11B17/12
Filed: 1968-09-16
Abstract: 1,197,839. Record changer. V-M CORP. 16 Sept., 1968 [25 Sept., 1967], No. 43896/68. Heading G5R. In an automatic record changer for random sized records stacked on the centre spindle of a turntable of a record player, a motor energized via photo-electric means responsive to the pick-up arm position drives a cam wheel through one revolution during which it controls the record change process including stopping the turntable when a record is deposited thereon and de-energizing the turntable drive when the last record has been played and the pick-up arm deposited in its outer rest position. An arm 130 secured to the pick-up arm support 30 is provided with a shutter member 132, Fig. 5, which exposes a photo-cell 136 to light directed via prism 134 from source 133 as the pick-up enters the run out groove at the end of record play. The cell energizes a motor driving cam wheel 50. Follower 84 co-operating with concentric cam groove 58 moves off the raised portion 56 and the resulting pivoting of rocker arm 78 raises pick-up arm 18 via member 100 and push-rod 106 and also operates clutch 70 to bring an end of arm 68 into frictional engagement with pick-up arm support 30. The member 68 is provided at its opposite end with a follower 66 which co-operates with cam track 56 to move the pick-up arm in a horizontal plane-initially to an outer position until the lowermost record in the stack is lowered to a record size-sensing position. This latter action and the subsequent lowering of the record on to the turntable is controlled by a further follower 49 co-operating with cam track 48 on the other side of cam wheel 50. This follower is mounted at one end of a bellcrank lever 44 having its other end co-operating with a row of balls 38 which extend up the centre spindle of the turntable and control the position of a set of fingers supporting the lowermost record in the stack. When the record has been lowered to the sensing position the pick-up arm is swung inwardly by arm 68 under the control of cam track 56 to engage the record edge-further movement of the arm being accommodated by slip in the clutch coupling the arm to the pick-up arm support 30. Thereafter cam track 56 controls outward movement of the pick-up arm by a fixed amount and subsequent inward movement by a greater fixed amount which aligns the pick-up over the start groove of the record. Before this latter, inward movement cam track 48 controls the lowering of the record on to the turntable and the subsequent raising of the record support fingers to their initial position. Thereafter follower 84 in cam groove 58 moves slowly up ramp 97 to raised position 86 in which rocker arm 78 pivots to lower the pick-up on to the record and releases clutch 70 to free the pick-up arm support for playing the record. When the last record has been played the first inward movement of the pick-up arm is not halted by a record at the record-sensing position and the arm moves inwardly until arm 130 secured to the pick-up arm support engages an upturned position 222 on a gate 210 and pivots same into the position shown in Fig. 8, whereby follower 66 operating in track 56 is now diverted to track 256. As a result the pickup arm is swung outwardly to its rest position and is locked in this position. After initial energization of the photo-cell via shutter member 132 at the end of a record and the subsequent energization of the cam motor a follower 144 on arm 138 moves off a raised position 64B in a cam track 64 and its pivoting operates a further shutter 142 whereby the cell is directly energized from the light source 133 for the duration of the change cycle. The pivoting of this cam 138 at the end of the cycle following the playing of the last record also unlocks the pick-up arm, so that it can then be lowered by means of the raised portion 86 of cam groove 58 into its lowered rest position, and this movement also switches off the turntable drive motor. A further cam track 62 serves to control the operation of a brake which stops the turntable when a record is being deposited thereon and means are provided for extending the length of the shutter arm 132 which co-operates with the photo-cell when 7-inch records, which have run out grooves nearer the record centre, are played.