Patent ID: 6713904
Filing Date: 2004-03-30
Classification: G11B,H02K

Abstract:
A voice coil actuator comprisinga core having an axis; a permanent magnet having a longitudinal axis, and positioned so that the longitudinal axis of the permanent magnet is substantially parallel to the axis of the core; a moving coil positioned to interact with the permanent magnet along the axis of the core; and a compensating coil positioned to interact with the moving coil, wherein a magneto-motive force in the compensating coil is controlled as a function of a position of the moving coil; wherein the compensating coil is positioned about the core; wherein the compensating coil extends along substantially the entire length of the core; and wherein the permanent magnet is positioned with respect to the core to define a cavity between the core and an end of the permanent magnet; and further wherein a second compensating coil is positioned in the cavity.