Patent GB-767884-A (GB)
Title: Improvements in or relating to gramophone record playing apparatus
IPC: G11B17/02
Filed: 1955-02-01
Abstract: 767,884. Gramophones. INDUSTRIES MUSICALES & ELECTRIQUES PATHE MARCONI. Feb. 1, 1955 [Feb. 8, 1954], No. 2968/55. Class 40 (2). In a gramophone record playing apparatus having a turntable speed control mechanism arranged to be set for playing a disc record at any of three different speeds as required by a particular record and a pick-up arm control mechanism arranged to operate in an automatic cycle in which on completion of the playing of a record the mechanism automatically lifts the pick-up arm 4a, moves it clear of the turntable 2 to permit delivery of the next record to be played and then moves the arm to a position corresponding to the commencement of the groove of such record, means are provided to modify so the automatic cycle at the highest and lowest of the three speed settings that the pick-up arm 4a after moving clear of the turntable 2 drops to its rest position instead of moving to commence playing another record, an automatic record-changing mechanism operating when the intermediate speed setting is used. By this invention the latter mechanism has only to operate at one speed and a desired interval between successive records is achieved. The pick-up arm control mechanism comprises a slide 4 carrying a ramp cam 4b, a lever 5 fixed to the pick-up arm supporting spindle 14, and a cam 3 rotatable about a pin 15 and having a pin 21 engageable by one limb 22b of a V-shaped spring 22 the other limb 22a of which is secured in a lever 13 pivotable on a pin 20 fixed to the mechanism cover panel 1. In operation, when the pick-up reaches the end of the record groove a connection not shown between the arm 5a of lever 5 moves the lever 13 clockwise to its broken line position and in so doing the blade 22b moves pin 21 to bring the edge of cam 3 into frictional driven engagement with the rotating spindle of turntable 2. Such engagement causes the slide 4 to move to the right, whereupon cam 4b causes the pick-up to be lifted from the record, a connection not shown between the arm 5a of lever 5 and the slide 4 rotates the spindle 14 to move the pick-up arm across the record to its rest position, and the arm 5b moves back a pawl 10 against the loading of a spring not shown, to the broken line position shown. On continued rotation of cam 3 the slide and pick-up arm commence a return swing, the latter to an extent determined by a notch in the pawl 10, and finally the cam 4b clears the spindle 14 to lower the pickup towards the commencement of the record groove. The means to modify this cycle comprise a pivotal arm 9 connected by a rod 8 to a lever 6 whose pivotal position on a shaft 19 is controlled by a knob not shown, which lever 6 through another rod 7 varies the turntable speed. When the speed control mechanism is set to 45 r.p.m. the arm 9 is in the full line position which results in the apparatus following the automatic cycle, but when set to 33 or 78 r.p.m. the arm 9 moves to the broken line position to render the pawl 10 inoperative which prevents the inward swing of the pick-up arm towards the record, and the arm is eventually lowered on to its rest, not shown, and thereby operates automatically the motor switch, not shown. The latter may also be operated through a connection, not shown, by the knob which controls lever 6. Playing may be interrupted manually by another control knob, not shown, mounted on shaft 19 and controlling a lever 11 attached to a spring-loaded rod 12 which may be moved to rock lever 13 clockwise to initiate engagement of cam 3 with the turntable spindle.