GB340225A - Improvements in or relating to gramophones - Google Patents

Abstract

340,225. Gramophones. COWEY, L. E., Archer Works, Kew Gardens, Surrey. Aug. 16, 1929, No. 32219/30. Divided on 340,006. [Class 40 (ii).] Returning sound-box to starting point.-Automatic mechanism for lifting a tone-arm 31 and returning it to starting position after playing a record comprises a rotary cam surface 43 adapted to engage a tappet plate 34 mounted on the tone-arm so as to lift the tappet plate and tonearm and swing them horizontally by frictional driving engagement with the tappet plate until the tone-arm is arrested at its starting position by an adjustable stop, after which the cam slips relatively to the tappet plate in order to lower the sound-box or pick-up. A rod 35, which is pivoted at its upper end to an arm 36 fixed to the pivoted part of the tonearm, is connected at its lower end to the tappet plate and this is attached by two pivoted links 37 to a bracket 38 on the sound conduit 32. A spring 40a, Fig. 4, acts on the links 47 to counter-balance the weight of the tone-arm. The cam 43 is fixed by arms 44 to a sleeve 42 on a shaft 15 which is driven from the gramophone motor 51 by gearing 54, 55, 56, and is capable of axial movement by means of a worm 71 on the shaft 15 and a worm wheel 72 carried by friction plates on the sound conduit 32. A clutch disposed between the sleeve 42 and a disc 57 fixed on the shaft 15 is automatically disengaged when the tone-arm starts its inward movement, and is re-engaged automatically when, at the end of playing, the inward movement of the tone-arm ceases and the shaft 15 is moved axially by the feeding action of the worm 71. The cam 43 then rotates and lifts the plate 34 and tone-arm and swings them outwardly by engagement with a shoulder 45 on the plate 34 until an arm 46 movable with the conduit 32 contacts with a pivotally-adjustable stop so as to cause the shoulder 45 to ride over the cam 43. Further rotation of the sleeve 42 lowers the cam 43 and allows the needle to engage the record. The actuating apparatus is mounted between frame plates 12, 13, and an arcuate opening provided in the upper plate 12 to accommodate the rod 35 is obscured by a plate 41 fixed to the bracket 38. The tone-arm 31 may be held in raised position by the engagement of a slidable latch 49 carried by the plate 46 with a collar 50 on the rod 35. The clutch between the shaft 15 and sleeve 42 may be operated as described in Specification 340,006, or by electromagnetic &c. means. The application of the invention to magazine gramophones is described in Specifications 339,973, and 340,006 [Class 40 (ii), Phonographs &c.].