Emergency head retract system for magnetic disc drives - uses kinetic energy stored in rotating spindle mass to provide energy to unload heads during power failure

摘要

The drive system includes a disc having a magnetic surface and supported for rotation on a spindle. A motor for driving the spindle and a linear motor with a positioner coil for radially moving a head support structure along the disc surface. A circuit responsive to an emergency condition causes the linear motor positioner coil to retract the head support structure. The spindle motor is a rotating magnet DC motor. Kinetic energy stored in the rotating spindle mass is used to provide the energy required to unload the heads upon the occurrence of an emergency situation. Under emergency conditions, the spindle motor windings are switched directly to the linear motor positioner coil. The spindle motor then acts as a generator to supply the head retract energy.