| 摘要 |
PURPOSE:To adjust a phase lock position automatically by fixing the delay amount of a variable delaying means until servo operation becomes stable so that a residual servo error is corrected. CONSTITUTION:When a phase reference signal S is inputted, the amount to be corrected is over a look at the contents of a phase detection counter 120 and set in a movement amount counter 145. Simultaneously, which direction the residual servo error is in is transferred to a movement direction flip-flop 146, and a correcting counter 147 forming a variable delay circuit counts up or down at the transfer time T1 by said movement amount. Then, the phase information in the phase detection counter 120 and the residual error information in a correcting counter 147 are processed at transfer time T2 by addition and subtraction to generate feedback information to a speed loop. At this time, the correcting counter 147 is stored with the contents of the residual error to be corrected, and once the correction is made, a phase-locked state having no phase error is entered instantaneously.
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