Methods and apparatus to detect surface characteristics on magnetic read/write heads

An apparatus for characterizing a hard disk drive, the hard disk drive comprising a magnetic disk and a head slider comprising read and write elements and a fly-height control for adjusting a clearance between the head slider and the magnetic disk, the apparatus comprising:

• a fly-height control circuit for applying a control signal to the fly-height control to adjust the clearance between the head slider and the magnetic disk;
• a read element sensing circuit for measuring an output of the read element;
• a touch-down detection circuit for providing a touch-down signal when a touch-down between the head slider and the magnetic disk occurs based on the measured output of the read element;
• and
• a controller circuit for receiving the touch-down signal from the touch-down detection circuit, and characterizing and providing an indication of the characterization of the hard disk drive based on the control signal applied to the fly-height control and on whether a touch-down has occurred.

A method of characterizing a hard disk drive, the hard disk drive comprising a magnetic disk and a head slider comprising read and write elements and a fly-height control for adjusting a clearance between the head slider and the magnetic disk, the method comprising:

• applying a control signal to the fly-height control to adjust the clearance between the head slider and the recording disk;
• measuring an output of the read element;
• determining if a touch-down between the head slider and the recording disk occurs based on the measured output of the read element;
• measuring the control signal to the fly-height control upon determining a touch-down between the head slider and the magnetic disk;
• and
• characterizing the hard disk drive based on the measured control signal to the fly-height control at the time of the detected touch-down between the head slider and the magnetic disk.