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Adjusting Fly-Height of MR Heads Based on Temperature and Pressure

IP.com Disclosure Number: IPCOM000015673D
Original Publication Date: 2002-May-02
Included in the Prior Art Database: 2003-Jun-20
Document File: 1 page(s) / 43K

Publishing Venue

IBM

Abstract

As Temperature increases, air density decreases, resulting in a decrease of the fly height of a MR Read/Write head. Likewise, with a decrease in Air Pressure, again a decrease in air density, within the drive platter enclosure the fly height also decreases. With the advent of high rotational speed drives (10K RPM and above) this decrease in fly height can result in a devastating head crash.

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Adjusting Fly-Height of MR Heads Based on Temperature and Pressure

As Temperature increases, air density decreases, resulting in a decrease of the fly height of a MR Read/Write head. Likewise, with a decrease in Air Pressure, again a decrease in air density, within the drive platter enclosure the fly height also decreases. With the advent of high rotational speed drives (10K RPM and above) this decrease in fly height can result in a devastating head crash.

This invention uses a thermistor to monitor the temperature and an air pressure transducer to monitor pressure, within the platter enclosure. This temperature/pressure information is fed to the microprocessor within the drive, which uses the temperature/pressure data to compensate fly height through a set of piezoelectric elements. The piezoelectric elements are mounted between the two opposing heads for each disk platter such that the opposing heads can be spread by the piezo element according to a table of empirically derived data. Thus, the processor within the drive obtains the current temperature and pressure data, this data then forms the address within a table of empirically derived voltage values, the voltage value that the given temperature and pressure map to, is then applied to the piezoelectric elements via a DAC, which provides for the adjustment in fly height.

Positioner Voice Coil

Comb Axle

Piezo Elements

Platters

Read/write Heads

Pressure Sensor

HDD Processor

Temperature Sensor

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