Device for supporting the pick-up arm in sound-reproducing apparatus, for example gramophones and pick-ups

摘要

846,099. Gramophones. STAAR, M. Oct. 22, 1956 [Aug. 14, 1950], No. 32140/56. Class 40 (2). A pick-up arm 3 is supported when out of operation by a part 8 of a rocking member 5 normally kept by a spring 9 in the Fig. 3 position, but which may be pivoted (about trunnions 6) by a downward thrust on the arm 3; this movement may be used (a) to cause a brush 26 to clean the sapphire 27 of the pickup ; (b) to bring the member 5 into the position of Figs. 5 and 6 wherein a spherical cap 7 locks the arm 3; (c) to disengage an idler roller 18 in the turntable drive; and (d) to open the driving motor circuit. (a) and (b). As shown, the spring 9, between a fixed lug 10 and a projection 12 on the part 5, has an over-centre action to snap the part 5 into its two end positions, but the locking function (b) may be omitted, the spring 9 then being replaced by a simple tension spring urging the part 5 into the Fig. 3 position. (c). When the part 5 is in the position of Figs. 5 and 6, the projection 12 engages an extension 19 of one arm of a toggle 20, 23, whereby the idler roller 18 mounted thereon is withdrawn, against a spring 24, from both the motor shaft 17 and the rim of the turntable 2. (d). Except when engaged by the projection 12 in the Fig. 3 position, a shaft 43, Fig. 6, cranked at 45, 46, is pulled by a spring 47 into the position shown, wherein a radial arm 44 engages a locking lever 38, pivoted at 39, to withdraw a catch 42 from the path of a button 37 on a bell-crank lever 34, 35 carrying a contact 33 engageable with spring contact leaves 31 controlling the motor circuit; in use, before the pick-up is placed on the record, its arm is moved outwards so that its lower arm 3SP1/SP rotates the bell-crank lever 34, 35 against the spring 40 to close the switch 31, 33; the spring 40 brings the catch 42 behind the button 37 to lock the switch " on "; at the end of playing the arm 3SP1/SP trips the catch 42 in a similar manner to the arm 44.