Patent GB-975993-A (GB)
Title: Improvements in or relating to automatic record changing gramophones
Inventor: GRANBY PETER HUGH
IPC: G11B17/16
Filed: 1962-07-31
Abstract: 975,993. Automatic record changing gramophones. MAGNAVOX ELECTRONICS CO. Ltd. June 10, 1963 [July 31, 1962], No. 29418/62. Heading G5R. In an automatic record changing gramophone in which a stack of records to be played is supported above the turntable and these records are dropped one at a time on to the turntable under the control of a change-cycle mechanism which also causes the pick-up arm to swing inwards and to be lowered on to a record which has just been dropped, the change cycle mechanism swings a pivoted member which carries with it, by a friction connection, a pick-up positioning member which acts on an arm which is rigidly connected to the pick-up arm so that the pick-up arm is swung inwards, movement of the pick-up arm continuing until the positioning member engages with a stop set by a gate mechanism in dependence upon the diameter of the last record dropped on to the turntable so that the stylus is lowered on to the edge of the record, after which the friction connection slips and the pivoted member continues to move by itself, the arm thus being freed so that the pick-up is free to move inwards independently of the positioning member whilst the record is played. In Fig. 1 a plate 11 is pivoted at 12 and guided by a pin (not shown) in a slot 16, the pin being surrounded by a spring (not shown) which presses plate 11 upwards and supports it. A record positioning plate 17 is attached to plate 11 by a pin 18 fixed to it and projecting through a slot 19 in plate 11. A similar pin 20 is attached to plate 11 and projects downwards through a slot 21 in plate 17, and the two plates are pressed together by springs (not shown) surrounding the pins. A pin 24 is rigidly fixed to an arm carried by the spindle to which the pick-up arm 27 is fixed, and is trapped between edge portions 22 and 23 of plates 11 and 17 respectively. During a change cycle, cam disc 9 rotates and causes plate 11 to rotate anti-clockwise, so rotating the pick-up arm until plate 17 is arrested by a step 28a, 29 or 30 engaging a stop (not shown in Fig. 1). Plate 11 continues rotating, the plate 17 slipping on it, and a push-rod (not shown) supporting the pick-up arm runs down an inclined surface 36 of the plate and lowers the pick-up on to the record. Friction between the push-rod and the pick-up arm prevents the latter rotating until it is lowered. When the stylus reaches the centre of the record an automatic trip mechanism starts cam disc 9 rotating again and the above operations are reversed to start a new changing cycle. The edge of pin 24 is bevelled so that forcible movement of the pick-up arm causes plate 11 to be depressed against its supporting spring. Gate mechanism. Fig. 3 shows the gate mechanism for adjusting the position of a stop member 34 which is engaged by the steps on plate 17. The stop member 34 is provided with a central slot 46 through which extends a pin 45 attached to the housing 44, and at its upper end carries a pin 49 which engages in a notched slot 50 formed in the wall of the housing; the member is biased upwards by a spring 47. A 7 inch record will not engage finger 54, and the stop member will remain in the position shown. A 10 inch or 12 inch record will depress the finger 54 sufficiently to allow the pin 49 to engage the step 52 or the end surface 50 respectively. When a record has been played the cam disc 9 (Fig. 1) causes member 57 to move to the left, causing stop member 34 to assume its uppermost position and allowing finger 54 to drop within the housing so that it offers no obstruction to the removal of records from the turntable. Further rotation of the cam disc causes member 57 to move downwards and restore stop member 34 and finger 54 to the positions shown. Operation of the cam disc. This may be as described in Specification 975,991. The cam disc 9 is located in the position shown in Fig. 1 by the engagement of a cam follower roller 38 in a recess 41 formed in the edge of the disc. To start the gramophone an arm 39 is moved manually to disengage the roller from the recess, and this movement is arranged to switch on the electric motor 4 and to bring the idler roller 1 into engagement with the spindle 5 so that the motor starts to rotate the disc and operate the change cycle. When the cam disc has rotated half a turn the roller 38 enters a recess 37 which is shallower than recess 41, and this causes pulley 1 to be disengaged but does not stop the motor 4. When the record has been played a trip mechanism (not shown) causes arm 39 to move so that the cam disc again moves through half a turn. If no further records are to be played the roller 38 then enters recess 41 and switches off the gramophone. If there is another record to be played, a plate 42 is held in the position shown by a trigger mechanism and prevents roller 38 entering recess 41. Manual operation. This is described in Specification 975,992. Rotation of a knob (not shown) causes a slide bar 61 to move to a first position where it switches on the electric motor 4 and, by means of a rod 78, depresses plate 11 and frees pin 24. The pick-up arm 27 is then free to be turned manually into the required position. The pick-up arm is supported just clear of the records by a push rod resting on the upper surface of plate 11. Movement of the slide bar to a second position depresses plate 11 still further, and so lowers the pick-up arm until the stylus rests on the record.