| 摘要 |
<p>PURPOSE:To accurately discriminate a tracking state by outputting an acceleration command from an output part based on a tracking state value from 2nd and 3rd storage devices. CONSTITUTION:The tracking state is discriminated by a back tracking deciding device based on a control signal duty measurement value from a 1st storage device 52 and a phase reference signal from a head switching (HSW) signal reader 55, and either '1' in the case of the front tracking or '0' in the case of the back tracking is outputted to the 2nd storage device 57. When the tracking state value is supplied from the back tracking deciding device 56 to the 2nd storage device 57, its previously stored data is supplied to the 3rd storage device 58. The data of the 2nd storage device 57 and the data of the 3rd storage device 58 are compared with each other by an acceleration pulse generator, and upon coincidence, a decision is first made as to whether the state is the front tracking or the back tracking, and when it is the back tracking, the acceleration command is supplied from an output 24 to an acceleration pulse generator 3. By this method, the tracking state accurately is decided.</p> |
