Seagate Technology Incorporated

Timothy A Madsen

Alex C Toy

Wei C Hsie

Nathan Curland

Daniel J O'Connor

Hua Liu

Michael Jon Roe

Lezlie A Hughes

Russell J Machelski

This invention presents a method and system for testing a disc drive head usable with a disc drive head testing device. The steps for this include determining an unknown electrical property of the head testing device. This is done by generating output signals at the output stage. The testing device property is then computed by solving for the unknown electrical property based on the output signals generated for each of the known test devices. For each disc drive head under test, the head is coupled to the input lead and exposed to a stored magnetic data pattern to generate a read signal at the input lead. The measured difference affects the generated read output signal. The read output signal is adjusted based on the testing device property and the measured property to compensate for differences in the measured property.

Method and apparatus for testing a magnetic head

A method of optimizing write current in a data storage system. The write current is optimized by measuring a bit error rate in the storage system as a function of the write current in the presence of background interference stress and adjacent track interference stress. An optimum write current level is determined as a function of the measured bit error rate.

Performance based write current optimization process

A DC offset voltage is added to the analog timing signal in a peak detection data recovery circuit to cancel the timing asymmetry from a magnetoresistive head signal. An AC timing asymmetry cancellation circuit uses a charge pump, buffer amplifier and resistor divider to produce the proper DC offset voltage automatically.

AC timing asymmetry reduction circuit including summing DC offset

A magnetoresistive sensor has an air bearing surface, first and second vertical contacts having contact edges generally perpendicular to the air bearing surface, a generally rectangular magnetoresistive region having a first edge that comprises part of the air bearing surface and a plurality of additional edges which do not comprise part of the air bearing surface, and a permanent magnet layer having a magnetization vector oriented at 45.degree. with respect to the air bearing surface, wherein the plurality of additional edges are generally within the permanent magnet layer. The magnetoresistive sensor provides a relatively square read sensitivity window because the sense current is maintained parallel to the air bearing surface throughout the magnetoresistive region. In addition, the sensor is lapping intolerant because the relative positions of the first and second vertical contacts and the magnetoresistive region do not change as the air bearing surface is lapped.

Vertical contact - canted magnet magnetoresistive sensor

A write circuit in a magnetic disc drive writes data to a magnetic disc based on a write signal received. The write circuit includes a magnetic write head, an H-switch, and a headroom assistance circuit. The headroom assistance circuit includes a voltage divider, a capacitor, and a charging circuit for charging and discharging the capacitor based on the write signals so that increased voltage appears across the magnetic recording write head during switching of the current polarity by the H-switch.

Capacitor assisted low voltage write circuit

A thin film magnetic read/write head deposited upon a magnetic substrate and including a shallow top pole take-off angle reduces leading and trailing undershoots in an isolated pulse signal. The undershoots are reduced by minimizing the magnetic discontinuities across the recording surface of the head, except for the recording gap.

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Bloomington, MN, United States of America

Timothy A Madsen