Bistable magnetic/electromagnetic latch for disk file actuator

A bistable magnetic/electromagnetic latch sub-assembly for releasably latching a disk file actuator in order to park data transducer heads at a predetermined location of a data storage disk rotatably mounted to a base within a fixed disk data storage subsystem, the latch sub-assembly comprising:

• mounting flange means for mounting to the base in operative proximity to the disk file actuator,
• latch body means rotatably mounted to the mounting flange means, the latch body means including permanent magnet means and actuator engagement means,
• plural detent pin means fixed to the mounting flange means and limiting rotational displacement of the latch body means and for coacting with the permanent magnet means to hold the latch body means at a release detent position and also to hold the latch body means at an armed detent position wherein the actuator engagement means is positioned to engage and latch the actuator, and
• electrical coil means fixed to the mounting flange in operative proximity to the permanent magnet means for generating switching fluxes for switching the latch body means between the armed detent position and the release detent position in accordance with the direction of an intermittent actuation current flow through the electrical coil means.

A method for controlling a bistable latch for a disk file actuator within a disk drive following removal of power, the disk drive including a DC brushless spindle motor, comprising the steps of:

• rectifying an output from the DC brushless spindle motor to obtain a direct current,
• splitting the direct current into a first path and a second path,
• applying the first path to return the disk file actuator to a head landing position, and,
• applying the second path to actuate the bistable latch to move it to an armed position for latching the disk file actuator at the head landing position.