| 摘要 |
PURPOSE:To decode exactly positioning information even if a revolving speed of a disk is varied, by generating a sink enable signal from a PLL and inputting it to a sink data detecting circuit and a sink data omission coping circuit. CONSTITUTION:An area which can detect sink data by a decoder of a PLL7 is formed newly, and its sink-enable signal is applied as an enable signal to a comparator 11 of a sink data detecting circuit 1, and also used as an input logical condition of a monostable circuit 21 of a sink data omission coping circuit 2. The circuit 21 is operated only when sink data has been detected in a sink-enable period T5, and during the period of its pulse width T, a phase comparing output signal from the PLL7 can be fed back. Also, when a difference T4 between a phase comparing timing and a sink data detecting timing is made shorter than that of a conventional device, a servo positioning signal can be decoded, when a spindle rotates in a wider range. |
