Patent ID: 7239471

Claim:
A method of setting the amount of power application to a heater incorporated in a magnetoresistive head for use with a magnetic disk drive that comprises a magnetic disk for storing information; a magnetoresistive head, which includes a heater for controlling a flying height over the magnetic disk and writes information onto and reads information from the magnetic disk; an integrated circuit, which carries a read/write circuit for the magnetoresistive head and a power application circuit for applying power to said heater; and a control processor, wherein said integrated circuit includes a resistance measurement circuit for measuring the resistance of said magnetoresistive head, the method comprising: connecting to said magnetic disk drive a computer that stores the relationship between the amount of a resistance change in said magnetoresistive head and a temperature rise, the relationship between a temperature rise and the amount of magnetoresistive head protrusion, and a permissible temperature rise value for magnetoresistive head life optimization; causing said control processor to control said resistance measurement circuit in accordance with instructions from said computer, measure an initial resistance value of said magnetoresistive head, and output the measured value to said computer; starting to apply power to said heater, and causing said resistance measurement circuit to measure the resistance of said magnetoresistive head and output the measured resistance to said computer; causing said computer to calculate the amount of a resistance change in said magnetoresistive head from a resistance value prevailing after power application to said heater and from said initial resistance value; determining the amount of a temperature rise in said magnetoresistive head from the amount of said resistance change; determining the amount of protrusion of said magnetoresistive head from the amount of said temperature rise; judging whether a predetermined protrusion amount is reached by the amount of said protrusion; increasing the amount of power application to said heater when the amount of said protrusion is smaller than the predetermined protrusion amount; and storing, when the predetermined protrusion amount is reached by the amount of said protrusion, the prevailing amount of power application in said control processor as the amount of power application to said heater.