Monostable active latch for a disk drive actuator

Abstract

A monostable active latch apparatus is disclosed for use in a hard disk drive which has a housing, a rotating data storage disk and an actuator mounted in the housing. The actuator controllably positions a read/write head over a predetermined portion of the disk and includes a voice coil motor coil carried by a yoke portion of the actuator. The active latch uses a permanent magnet to bias an elongated rotatable latch arm into engagement with the actuator when the actuator is positioned in the landing zone. An electromagnet coil, positioned between the magnet and the magnetic return plates, when energized, counters this bias, permitting the latch arm to rotate, counterclockwise, out of engagement with the actuator. When the coil is deenergized, the permanent magnet provides a clockwise torque on the arm, raising the latch end of the latch arm to a first position out of the path of the actuator. When the coil is energized, the latch end of the latch arm is driven to a second position beneath the rear end of the actuator. If the coil is deenergized while the actuator is positioned in the landing zone of the disk, the latch end of the latch arm catches and latches the actuator, preventing further rotation of the actuator until the coil is again energized and the actuator moved away from the landing zone.