High quality record turntable - uses hydrodynamic bearings and controlled speed drive with velocity feedback tachometer

摘要

The design consists of a turntable (1) with a large truncated cone shaped central projection which rests in a suitable bearing (2) separated from it by a film of low viscosity oil. Slots are cut in the central projection according to accepted hydrodynamic bearing design practice. At the circumference of the table a dust exluding configuration (3) and a drive arrangement (4, 5) are mounted. This consists of a toothed cylinder (4) driven by a coil (5) mounted on the chassis of the equipment (6). Two alternative forms of central hydrodynamic bearing are available both cylindrical rather than cone shaped. In one case the table drive is provided by a motor incorporated in the table, while a velocity feedback control circuit is driven from a tachogenerator again incorporated in the table. Alternatively a magnetically coupled digital velocity transducer may be used.