| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a rotational-speed control device for a motor capable of exactly and easily measuring an error in a rotational-angle detector assembled into a spindle device, and to provide a highly accurate static-pressure gas bearing spindle device of which the rotation is controlled by the control device. <P>SOLUTION: With a mark plate 21 having a plurality of detection marks provided on a rotating shaft 1 at uniform intervals in the circumferential direction, the rotational-angle detector 30 outputs a plurality of rotational-angle detection signals at intervals of uniform rotational angle during one turn of the motor 29 by the detector 24 provided on a fixed section 4. A reference signal generator 34 produces a reference signal of a fixed cycle. A feedback control computation device 35 produces a motor driving current command signal from the rotational-angle detection signal and the reference signal by computation. The rotational-speed control device 32 includes a constant-current driving signal generator 37 for generating a fixed constant-current driving signal not dependent on the rotational-speed detection signal, and a change-over switch 38 changes over a command signal to a power supply 36 between the motor driving current command signal and the constant-current driving signal. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
