1. Field of the Invention
This invention relates to an actuator unlocking apparatus and a method of releasing an actuator from magnetic attraction during power-on operation, in a disk storage apparatus. An actuator for moving a transducer head on a disk storage medium is locked by a magnetic locking apparatus to prevent the actuator and the disk storage medium from being damaged by unintentional movement of them when the disk storage apparatus is not powered. This invention relates to an improved method of and apparatus for releasing an actuator from magnetic locking apparatus at power-on operation.
2. Description of the Prior Art
In a disk storage apparatus, it is necessary to prevent an actuator (a voice coil motor (VCM), etc.) for moving a transducer head on a recording medium from moving due to external force and from damaging data on a recording surface and the actuator itself, by locking the actuator when the disk storage apparatus is not powered. In a small disk storage apparatus, the magnetic attraction of a permanent magnet is used to lock the actuator.
In this prior art configuration, owing to the magnetic attraction of -the permanent magnet, power is not consumed except when locking is released during a power-on operation. Further, in this configuration, the dimensions of the disk storage apparatus can be reduced because there is mechanically no movable part. Since the power of the actuator is used to unlock, a dedicated electric circuit for unlocking is not needed. Still further, in the configuration, component parts are merely the permanent magnet and its attaching members. Therefore, the configuration is generally adopted because of the advantage that the number of parts is small and a cost can be reduced. The present invention relates to an unlocking apparatus and method of a disk storage apparatus which unlocks an actuator from the permanent magnet.
In prior art, in order to release the actuator from the permanent magnet, positional information (servo information) written between a zone where the actuator is locked (parking zone) and a zone where data is recorded (data zone) on a disk recording medium is used and a seek operation is used for releasing. That is, during a releasing operation, a position of the actuator is detected by reading the positional information and the current which is supplied to the actuator is controlled. The actuator is surely released from the permanent magnet and moved to the data zone. The situation in which the releasing cannot be completed because of insufficient movement or in which the actuator collides with a crash stop due to the excess movement of the actuator is avoided by reading positional information on the disk.
However, the servo information written between the parking zone and the data zone on the disk medium may disappear due to the friction between the transducer head and the disk medium if the actuator is locked and released many times, because the parking zone is a zone on which the transducer head attached to the actuator slides when the rotational rate of the disk is below a predetermined value (contact start and stop). Once the servo information is lost, releasing cannot be completed because the positional information for the releasing cannot be obtained any more. In the prior art, there is therefore a problem in terms of reliability.