| 摘要 |
PURPOSE:To control two diameter axis-wise movements of a levitation plate by obtaining a signal which is proportional to a diameter axis-wise rotation angle of a levitation plate from a differential signal of output values between potential sensors and by controlling an excitation current of an electromagnetic coil based on the signal to change magnetic flux between a yoke part and the levitation plate. CONSTITUTION:A signal which is proportional to a diameter axis-wise rotation angle of an levitation plate 100 is obtained from a differential signal between outputs of two displacement sensors 203a, 203c on a diagonal line. An excitation current of an electromagnetic coil 303 connected to a quartered yoke part 302 is controlled based on the signal, and flux 311 between the yoke part 302 and the levitation plate 100 is changed to control two diameter axis-wise movements. The four yoke parts 302 form a pair of two yoke parts on a diagonal line, and energize the excitation coil 303 to produce magnetic flux in reverse direction each other. The magnetic flux 311 by the excitation coil 303 passes through the levitaiton plate 100, the yoke part 302, an electromagnetic core 304, a connecting yoke 305 and the levitation plate 100. |
