Recording/reproducing device having a bypassing pole electromagnetic

Abstract

A disk drive having an electromagnetically actuated latch mechanism for latching and unlatching the movable actuator of the disk drive. The electromagnetically actuated latch has a magnetic circuit structure including a two legged yoke which mounts a coil. A keeper forming part of a latch lever is pivotally mounted for rotation about an axis located beside the yoke structure. The keeper defines two air gaps with the yoke, a variable reluctance air gap with one leg and a substantially constant reluctance air gap with the other leg. A spring biases the latch lever to latched position. In the latched position of the latch lever, the torque couples acting on the latch lever due to flux coupling of the keeper at the variable reluctance gap and the substantially constant reluctance gap, produce torque couples acting in the same direction on the latch lever, minimizing the current requirement to move the latch lever from latched position to unlatch the actuator. This magnetic gap configuration in the magnetic circuit minimizes reluctance variations in the magnetic circuit and variations in the torque constant between the extremes of angular displacement of the keeper. Integration in a disk drive is accomplished employing increased angular displacement of the latch lever and shorter magnetic and latch moment arms.