Patent ID: 7327054
Filing Date: 2008-02-05
Classification: H01F,H01L,H02K

Abstract:
1. A linear actuator for driving an actuation arm comprising: a magnetic field; a first coil that is controllably movable within the magnetic field by adjusting a current flowing through the first coil whereby to drive the actuation arm; a second coil that is movable with the first coil and configured such that a voltage is inducible in the second coil that is proportional to its velocity; a third coil that is configured to induce a transformer voltage that is opposite to a transformer voltage induced in the second coil when the first coil is carrying a current, wherein the third coil is stationary and is wound on a central yoke about which the first and second coils are arranged; and a controller device connected to the second coil for receiving feedback indicating the voltage induced in the second coil whereby a velocity of the actuation arm is determinable, wherein the controller device is further connected to the first coil and is operative to adjust the current flowing in the first coil based upon said feedback for controllably driving the actuation arm.