Patent ID: 6118613
Filing Date: 2000-09-12
Classification: G11B

Abstract:
An electromagnetic actuator drive circuit for controlling a drive current of an electromagnetic actuator in accordance with a signal from a signal source, a displacement of the electromagnetic actuator being displaced in accordance with the drive current, said drive circuit comprising:a drive-current control circuit for controlling the drive current of the electromagnetic actuator in accordance with the signal from the signal source;feedback control means for controlling the drive current by negative feedback of a terminal voltage of the electromagnetic actuator and by positive feedback of a terminal current of the electromagnetic actuator,said feedback control means includinga current detector detecting a terminal current of the electromagnetic actuator and outputting a voltage indicative of the terminal current, anda subtractive signal synthesizer operatively connected to said current detector, said subtractive signal synthesizer subtracting a terminal voltage of the electromagnetic actuator from the voltage indicative of the terminal current to produce a synthesized signal; anda first current source operatively connected to said subtractive signal synthesizer and converting the synthesized signal to a feedback signal,wherein the feedback signal is fed back into the drive current.