Finnegan, Henderson, Farabow & Garrett
Turntable apparatus
 Disclosed is a turntable apparatus which comprises a plurality of magnets provided on the inner surface of the turntable so as to be disposed in a state alternately opposite in polarity and a plurality of coils provided on a stationary substrate disposed to face said turntable, in a manner that the disposition of said plurality of coils is in corresponding relation to the disposition of said plurality of magnets, whereby said turntable is rotated by the electromagnetic force between said coils and magnets. There is provided on said stationary substrate position detecting means for detecting the electromagnetic position of the magnets relative to the coils. The output signals from said position detecting means vary in level with a magnetic field variation due to the rotation of the turntable. There is provided means for controlling supply of a DC current to each coil upon receipt of an output signal from said position detecting means thereby to cause a rotating magnetic field to be produced in the coils. Further, there is provided means for operatively comparing a specific reference voltage with that inductive voltage induced in the coil which is proportional to the rotation speed of the turntable, thereby to control supply of a current to the coil from a power source, thus to control the flow of current supplied from said power source to the coil, i.e., the rotation speed of the turntable. 
Tokyo Shibaura Electric Co., Ltd.
H G G
H02K G11B G11B
inventional inventional inventional
Masato Shigeo Terumoto Manabu
Nagata Fukui Watanabe Okamura