Disk drive calibrating bias signal for touchdown sensor

摘要

A disk drive is disclosed comprising a head actuated over a disk, the head comprising a touchdown sensor comprising a resistance. A bias signal is applied at a reference value to the touchdown sensor at a reference temperature, and a corresponding reference resistance of the touchdown sensor is measured. An operating value for the bias signal is generated based on a predetermined operating temperature of the touchdown sensor, the reference resistance, the reference temperature, and a thermal coefficient of resistance (TCR) of the touchdown sensor, wherein the TCR specifies a change in temperature of the touchdown sensor relative to a change in the resistance of the touchdown sensor.

主权项

1. A disk drive comprising:
a disk; a head actuated over the disk, the head comprising a touchdown sensor comprising a resistance; a fly height actuator; and control circuitry operable to:
apply a fly height control signal to the fly height actuator to control a fly height of the head;configure the fly height control signal to substantially zero and apply a bias signal at a reference value to the touchdown sensor at a reference temperature and measure a corresponding reference resistance of the touchdown sensor;estimate an operating resistance of the touchdown sensor at a predetermined operating temperature of the touchdown sensor based on the reference resistance, the reference temperature, and a thermal coefficient of resistance (TCR) of the touchdown sensor, wherein the TCR specifies a change in temperature of the touchdown sensor relative to a change in the resistance of the touchdown sensor; andconfigure the fly height control signal to achieve a target fly height of the head and generate an operating value for the bias signal by adjusting the bias signal until a measured interim resistance of the touchdown sensor substantially equals the operating resistance.