Patent ID: 6577474
Filing Date: 2003-06-10
Classification: G11B

Abstract:
A voice coil motor assembly in a head disc assembly of a disc drive, the head disc assembly having a base plate and a top cover enclosing a data storage disc rotatably mounted on a drive motor, and an actuator arm for transferring data to and from the disc; the voice coil motor comprising:a bottom pole attached to the base plate; a permanent magnet set including a pair of magnets with opposite polarity faces lying in a common plane between the bottom pole and the top cover for generating a magnetic field between the bottom pole and the top cover; a top pole connected to an outer surface within a recessed region of the top cover above the bottom pole for providing a return path for the magnetic field generated by the permanent magnet set, wherein the outer surface does not have an opening therethrough; and a voice coil attached to the actuator arm and positioned within the magnetic field between the bottom pole and the top cover.