Patent GB-215252-A (GB)
Title: Automatic phonographs
IPC: G11B17/00
Filed: 1923-09-10
Abstract: 215,252. Daily, W. H. Sept. 10, 1923. Multiple machines; driving.-A multiple gramophone has a number of turntables, fixed in position, arranged in a circle, a single tone-arm and soundbox adapted to be swung round to each record in succession, and a rotating cam-device adapted to lift each turntable to bring it into engagement with the stylus of the sound-box. The turntables and other moving parts of the machine are driven by a single electric motor of the induction-meter type. Fig. 5 is a vertical section through the central sound column 7 leading from the tone-arm and the spindle 2 of one of the turntables 6. The rotor 22, 22<a> of the motor is mounted to rotate round the tube 7 and has a driving rim 34 adapted to engage and drive a friction wheel 2<a> on the spindle 2 when the spindle is raised by a cam device to the position shown. The rotor 22 drives a vertical shaft 16 carrying, at the top, a pinion 17 and a bevel pinion 16<1> adapted to drive respectively, through suitable gearing, a rotating plate 12 which carries round the tone-arm, and a rotating cam-device for elevating the turntables. A two-speed gear is provided between the rotor 22 and the shaft 16 so that either ten-inch or twelve-inch records can be played, the movements of the cam and the tone-arm being slower when the larger records are used. This two-speed mechanism comprises two spur wheels 16a, 24 constantly driven by the hub of the rotor 22 and loosely mounted on the shaft 16. One or other of the wheels is locked to the shaft by a sliding clutch 25. The tone-arm T, Figs. 1 and 2, is mounted on the top of the sound column 7 to rotate horizontally and also to move up and down about an axis 7a. Projecting downwardly from the tone-arm is a leg 8 which, when the tone-arm is being carried from one record to the next, rests on the rotating plate 12. To ensure that the tone-arm shall be stopped in the correct starting position for a new record, the leg 8 has a projection 10 adapted to engage one of four stops 40 carried by a plate 40a mounted beneath the rotating plate 12. The plate 40a can be angularly moved a limited amount to adjust the position of the stops for ten-inch or twelve-inch records. The cammechanism for raising the turntables comprises a rotating-sector 31, Figs. 5, 6 and 7, carrying a cam-rail 50 adapted to pass under the toe of the turntable spindle 2. The cam-rail 50 which is pivoted on a vertical pivot 51 a.t the front, is, as the sector 31 rotates, pressed outwards into the operative position by a fixed projection 53, Fig. 6, and is held out against the pull of a spring 52, until the tail escapes from a second projection 55a carried by an arm 55 which can be angularly adjusted to vary the position of the projection 53 to adjust for different lengths of records. When the tail of the cam slips off the projection 55a, the cam moves inwards and releases the spindle 2 so that the turntable drops and the tone-arm falls on the rotating plate 12 and is carried round to the next record. A' centrifugal governor with adjustable brake-pad is provided. As shown in Fig. 8, the pad 75 is carried by a pivoted member 76 controlled by a spring 77 and an adjusting screw 78.