Patent ID: 6429999
Filing Date: 2002-08-06
Classification: G11B

Abstract:
A hard disc drive assembly having a base plate, one or more hard discs rotatably mounted on the base plate for rotation about a spin axis, and an actuator assembly rotatably mounted adjacent each disc positioning a plurality of read/write heads over selectable radial positions on each disc, the drive assembly comprising:a boss on the base plate; an actuator arm pivotally supported from the base plate for rotation about an axis parallel to the spin axis, the arm carrying the heads at one end thereof and having a generally flat voice coil mounted at an opposite end thereof, the voice coil being wound about an axis parallel to the spin axis; an assembled unit including a voice coil magnet assembly comprising a bottom magnetic return plate having a generally flat upper surface lying in a plane normal to the spin axis, a top magnetic return plate spaced above the bottom magnetic return plate having a generally flat underside, and a pair of upper magnets mounted to the underside of the top return plate, each magnet having a generally flat plate shape, one of the magnets generating a magnetic field passing through the voice coil between the return plates in a first direction parallel to the spin axis and the other of the magnets generating a magnetic field passing through the voice coil in a second direction opposite to the first direction parallel to the spin axis, wherein the assembled unit is rotatably attached to the boss to sandwich the voice coil between the top return plate and the bottom return plate, wherein the top magnetic return plate and the bottom magnetic return plate are fastened together in the assembled unit prior to attachment of the assembled unit to the boss.