Patent GB-204771-A (GB)
Title: Improvements in or relating to gramophones and the like
IPC: G11B3/095
Filed: 1922-07-04
Abstract: 204,771. Cotton, A., F. R. July 4, 1922. Returning sound-box to starting-point; raising, positioning, and lowering sound-boxes. - In a gramophone or the like, repeating-mechanism whereby the sound-box is raised and returned to a predetermined position comprises a bar travelling with the sound-box and adapted to be displaced, so as to lift it, by a blow delivered by a projection on the turntable. The projection acts upon a movable member carried by the bar, the blow occurring when the tone-arm has reached a position determined by the setting of the movable member upon the bar. In the construction shown, the tool-arm is supported upon a bridge b, and is provided with lugs a', d<1> forming bearings in which a bar e can rotate on a longitudinal axis. The bar carries at one end a cam f which is adjacent to the sound-box c but is normally out of contact therewith, and at the other end is a catch e<2> which can be engaged in either of two positions by a spring-controlled detent h, Fig. 3. On a part of the bar e that is preferably of square. section is a slidable carriage i, which carries a rubber-tyred roller k adapted to engage the rim of the turntable when the tone-arm brings. it into contact therewith, the point of engagement being varied according to the position of the carriage i on the bar e. This position is adjusted by means of a pinion operated by a knob i<2> and engaging rack teeth on the bar. The roller k carries two stop-pins k<1>, adapted to abut against a web i<4> on the carriage i, and also an arm k<2> which, when the roller is rotated by the turntable, advances a lever -arm i<5> into the path of a projection l on the turntable. The arm i<5> is pivoted on the web i', and normally hangs vertically. When the lever is struck by the part l, it causes the bar e to rotate axially, whereupon the cam f lifts the sound-box off the record, and the tone-arm is then swung back towards the starting-point, either by the force of the blow or by a spring (not shown) or a weight. An adjustable stop m, Fig. 3, determines the point to which the tone-arm is returned, the stop comprising a spring plunger adapted to slide in a cylindrical guide, in which it is adjustably clamped by an L-shaped lever m<2>. The detent h, which is pivoted on the lug a<1>, engages with the catch e<2> as shown in Fig. 3 when the bar e has been rotated, thus holding the soundbox raised: when the detent strikes the stop m, it is tripped and releases the catch, allowing the sound-box to fall on to the record. The descent is preferably checked by an eccentric f<2> which is pivoted on the cam f, and trails upon the record. The roller k is put out of balance, by suitably perforating it, so that it resumes its normal position when the arm i<5> escapes from the projection l. The projection l may be a roller mounted upon a pin, or may consist of a pivoted spring-controlled pawl. Instead of acting upon an arm i<5>, it may strike the base of the wheel k or a projection thereon. The bar e may be balanced, and provided with a crank arm upon which the stop m acts, the detent h being dispensed with in this case.