GB390750A - Improvements in or relating to the recording and reproduction of sound - Google Patents

Abstract

390,750. Gramophones. NYSTROM, C. W. 20, Ostra Torggatan, Karlstad, Sweden. Oct. 19, 1932, No.29251. Convention date, Oct. 19, 1931. [Class 40 (ii).] The arrangement described in Specification 385,807 for driving a turntable, so that the record is tracked by the recorder or reproducer at a constant speed, by a driven friction roll with peripheral ridges engaging a spirally grooved surface on the turntable or on a disc moving therewith, the driving roll being traversed radially by the grooved disc, is provided with means for disengaging the friction roll drive automatically at predetermined positions of the stylus in its traverse over the record. Transmission gear for moving the recorder or reproducer radially by, and in relation to, the radial movement of the friction roll is also provided. Figs. 1 and 2 show a turntable 61 connected with a disc 19 having a spiral groove on its underside engaged by a driven friction roll 27 slidable on a shaft 21 carried in a pivoted frame 23 which is supported with the roll 27 in contact with the disc 19 by a cam 47 acting through a spring 110. A bracket 63 movable with the roll 27 and carrying rollers 65, 65a riding on a rod 20 of the frame 23 is connected by links 83, 84 and an arm 85 with the vertical pivot 86 carrying the arm 90 and pick-up or recorder 91, which is thereby swung across the record as the roll traverses the disc 19. The record drive mav be arrested with the needle at various distances from the centre by means of a bell crank lever 71 pivoted on a slide 75 which is adjustable by a resilient arm 78 engaged in a notched plate 80. A roller 73 on one arm of the bell-crank extends under a bail 67 fixed to the spindle 68 of the cam 47, and a roller 74 on the other arm of the bellcrank extends into the path of the roller 65a on the bracket 63 and is engaged thereby after the predetermined traverse of the driving roll and the needle as set by the slide 75, thereby rocking the bell-crank and consequently the bail 67 and cam 47 so that the roll 27 is no longer supported in driving engagement. The Specification as open to inspection under Sect. 91 describes a modification in which the recorder or reproducer is traversed radially across the record by supporting it from a bracket which is moved along a guide rod by the sliding movement of the friction driving roll. This subject-matter does not appear in the Specification as accepted.