Disk drive comprising extended range head proximity sensor
View Patent ↗A disk drive is disclosed comprising a head actuated over a disk, and a fly height transducer operable to generate a fly height signal for the head. The disk drive further comprises control circuitry comprising a current sensor operable to detect a current flowing through the fly height transducer. The current sensor comprises a differential amplifier operable to amplify the current flowing through the fly height transducer over a first range using a first gain, and amplify the current flowing through the fly height transducer over a second range using a second gain less than the first gain, wherein at least part of the second range is different than the first range.
1. A disk drive comprising:
a disk;
a head actuated over the disk;
a tunneling sensor; and
control circuitry comprising a current sensor configured to detect a current flowing through the tunneling sensor, the control circuitry configured to:
detect a proximity of the head relative to the disk in response to the detected current flowing through the tunneling sensor; and
detect the head contacting the disk in response to the detected current flowing through the tunneling sensor,
wherein the current sensor:
operates at a first gain over a first range corresponding to a first fly height; and
operates at a second gain over a second range corresponding to a second fly height, wherein the second fly height is lower than the first fly height.
2. The disk drive as recited in claim 1 , wherein the tunneling sensor operates at a large resistance relative to a stimulus.
3. A method of operating a disk drive, the disk drive comprising a head actuated over a disk, and a tunneling sensor, the method comprising:
detecting a current flowing through the tunneling sensor;
detecting a proximity of the head relative to the disk in response to the detected current flowing through the tunneling sensor; and
detecting the head contacting the disk in response to the detected current flowing through the tunneling sensor,
wherein detecting the current flowing through the tunneling sensor comprises:
detecting the current at a first gain over a first range corresponding to a first fly height; and
detecting the current at a second gain over a second range corresponding to a second fly height, wherein the second fly height is lower than the first fly height.
4. The method as recited in claim 3 , wherein the tunneling sensor operates at a large resistance relative to a stimulus.