| 摘要 |
<p>A spindle servo system for in an apparatus for recovering a signal from a track on the surface of a disc, wherein the signal includes a signal defining a time base, and the system includes optical system for directing a source beam of radiation to the track and for directing a modulated beam of radiation containing the signal to a signal recovery device for recovering the signal from the modulated beam, the spindle servo system comprising: a spindle motor for rotating the disc whereby relative motion between the disc and the source beam produces the modulated beam; a spindle tachometer including first and second tachometer elements coupled to the spindle motor, for producing first and second spindle tachometer signals, indicative of the actual angular rate of rotation of the spindle motor; a spindle reference signal generator for producing a spindle reference signal representing a desired angular rate of rotation of the spindle motor; a device for comparing each of the first and second spindle tachometer signals with the spindle reference signal, to produce first and second error signals representative of the detected differences therebetween; and an adder for summing together the first and second error signals to produce a spindle motor control signal for coupling to the spindle motor to produce the desired angular rate of rotation.</p> |
