| 摘要 |
PURPOSE: To quickly and exactly perform emergency check by discriminating the occurrence of an emergency state when either of discriminated result of incapable reading of an proper address or the rotating speed of a spindle motor out of a prescribed range is obtained. CONSTITUTION: The rotating information of a spindle motor 2 is obtained also as an FG pulse from a frequency generator 21 mounted on the motor 2. The width of the FG pulse inputted to an FG pulse detecting part 22 is reduced to a timeΔt, supplied to a system controller 11 and counted for every input ofΔt by means of a counter 11a inside. Emergency check is performed whether or not the valueΔt is within the allowable range of a required CLV rotation period. On the other hand, when the reading of address is not obtained after the normal rotation of the motor 2 is judged and the value of of an address reading timer 11b in the controller 11 is judged in the state without resetting the time counting operation. Namely, when the value is longer than the prescribed time, it is judged that the emergency state occurs.
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