Patent ID: 6549380
Filing Date: 2003-04-15
Classification: G11B,H02K

Abstract:
A disc drive having a data storage disc rotatably mounted on a base plate, an actuator mounted on the base plate adjacent the disc for moving a transducer over the disc, and a voice coil motor coupled to the actuator, the voice coil motor comprising:a voice coil; a first magnetically permeable plate; a permanent magnet pair coupled to the first magnetically permeable plate, the permanent magnet pair defining a magnetic planar surface and producing a magnetic flux; and a second magnetically permeable plate having a planar surface and a raised magnetically permeable plate portion protruding from the second plate planar surface, the raised plate portion defining a raised planar surface parallel to the second plate planar surface and opposite the magnetic planar surface and being formed of non-permanent magnetic material, wherein the second plate is positioned in spaced relation to the first plate forming an air gap between the raised planar surface and the magnetic planar surface through which the voice coil is free to move, the raised planar surface having a shape complimentary to a surface shape of the magnetic planar surface such that the magnetic flux passing across the air gap between the permanent magnet pair and the raised plate portion is substantially uniformly directed through the voice coil in a direction orthogonal to the magnetic planar surface.