Patent ID: 6820020
Filing Date: 2004-11-16
Classification: G11B

Abstract:
A method of determining a magnitude of a sensing current to be supplied to an electromagnetic transducer, comprising:supplying an electric current of a first current value to the electromagnetic transducer; determining a physical quantity appearing in the electromagnetic transducer based on the electric current of the first current value; supplying an electric current of a second current value, different from the first current value, to the electromagnetic transducer; determining the physical quantity appearing in the electromagnetic transducer based on the electric current of the second current value; deriving a variation in temperature of the electromagnetic transducer based on the change in the physical quantity; determining the magnitude of the sensing current based on a derived variation in temperature of the electromagnetic transducer; deriving an expected lifetime of the electromagnetic transducer based on the variation in temperature when determining the magnitude of the sensing current; comparing the expected lifetime with a predetermined target upper limit lifetime; and adding an incremental value to a preceding second current value so as to set a new second current value if the expected lifetime takes a value exceeding the predetermined target upper limit lifetime.