GB401751A - Improvements in or relating to sound reproducing devices - Google Patents

Abstract

401,751. Gramophones. ELECTRICAL RESEARCH PRODUCTS, Inc., 195, Broadway, New York, U.S.A.-(Assignees of Elmer, L. A., 102, Riggs Place, West Orange, New Jersey, U.S.A.) May 23, 1932, No. 14598. Convention date, July 22,1931. [Class 40 (ii).] The effect of extraneous vibrations and the lateral component of the friction drag between the stylus of a pick-up on a pivoted arm and the record groove is compensated for by designing the arm and counterweighting its pivoted end so that a pivot axis for the arm passes through the centre of percussion of the device about an axis through the stylus point parallel to that axis, and by arranging a spring between the arm and a stationary support so that it balances the drag component. This spring may also be adjusted to regulate the pressure of the stylus on the record, or a separate spring may be used for this purpose. In Fig. 2 the arm 13 carrying the pick-up 12 and mounted between horizontal pivots 14 carried by a vertical pivot is so designed and weighted at 16 that its centre of percussion with reference to the stylus is near the pivot 14. A spring 17 extending between a bracket 20 on the arm and a fixed bracket 19 is arranged so that it is parallel with the axis of the arm when this is tangential to the groove engaged by the stylus but exerts a turning action on the arm in other positions to compensate for the lateral drag. The fixed bracket may be adjustable vertically so as to regulate the pressure of the stylus on the record.