| 摘要 |
A latch assembly used for latching an actuator in a disc drive. The latch assembly comprises a coil assembly for selectively generating magnetic fields of alternating polarity in a pair of magnetically permeable plates. The plates are separated by a vertical gap which includes a coil, so that the passage of electrical current through the coil establishes magnetic polarities within the plates. Adjacent the coil assembly is a rocker assembly which is pivotable about a horizontal axis and comprises a latch arm and a coil arm, both of which extend in opposite directions from a central hinge portion. The distal end of the coil arm includes a permanent magnet which alternately detents between positions proximate to the plates of the coil assembly. The latch assembly latches the actuator by energizing the coil, which establishes a magnetic field in the plates that interacts with the magnetic field of the permanent magnet to move the coil arm proximate one of the plates, causing the rocker assembly to pivot so that the distal end of the latch arm latches the actuator. To unlatch the actuator, a current is applied to the coil to establish a magnetic field of opposite polarity, so that the coil arm moves to a position proximate the other one of the plates, causing the rocker assembly to pivot so that the latch arm moves out of the way of the actuator, allowing free movement of the actuator. The gap between the coil arm and the coil assembly when the actuator is latched is less than the gap between the coil arm and the coil assembly when the actuator is unlatched. The attraction between the permanent magnet and the plates is sufficient without application of the magnetic fields to maintain the orientation of the rocker assembly.
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