| 摘要 |
PROBLEM TO BE SOLVED: To highly reliably detect a servo sector by confirming whether on hot a servo pulse is generated in a prescribed period, e.g. an assert prohibition period of a servo signal or an assert leave period. SOLUTION: An expected value A is selected by selectors 403, 405, and a comparator 402 compares a count value of an increment counter 401 with the expected value A by the selectors 403, 405 while the increment counter 401 counts up, and when they agree, the increment counter 401 is reset, and the selector 405 is switched so as to select the expected value B. The comparator 402 informs an MPU the detection of 'missing of tooth' when the count value of the increment counter 401 coincides with the expected value B selected by the selector 405. A servo timing confirmation circuit 400 is provided related to respective index pulse 101, servo pulse 106 and servo gate 102 of a signal to be checked.
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