| 摘要 |
<p>PURPOSE:To shorten the pull-in time of a phase servo and to improve the accuracy by detecting a phase difference between a regenerative CTL signal and an FG pulse signal by using a 3rd counter and correcting a phase comparison error to be generated in a phase circuit. CONSTITUTION:A phase error is included in a serrate wave output signal S16 based on a phase difference between the regenerative CTL signal S1 and the FG pulse signal S11. Then, the 3rd counter 73 is provided, and, for instance, a clock signal S60 as the clock signal of a microcomputer is started for counting at a rising point of the regenerative CTL signal S1, and when a counted value at the 1st rising point of the FG pulse signal S11 is held, a value V61 of this hold value S61 becomes a phase difference data between the regenerative CTL signal S1 and the FG pulse signal S11. Then, this value V61 is supplied to a calculation circuit 74 to be multiplied by a prescribed coefft. value K and followed by addition and subtraction with the serrate wave output signal S16, so that an error signal generated in a phase comparison stage can be eliminated.</p> |
