Maxtor Corporation

Seagate Technology Incorporated

Richard LeSage

David Scott McMurtrey

Steven W Meeks

Peter R Svendsen

William M Marvin, Jr

Duong Hong Nguyen

Lee Teng Boon

Tan Chin Kiong

W Craig Tomalty

Detection of head disk interference is provided by monitoring a hard disk drive characteristic related to disk rotation rate. A number of characteristics can indicate HDI. These include the magnitude of decreases in rotation rate, changes in the time-derivative (time-rates of change) of rotation rate or other changes in time-profiles of rotation rate, changes in spin motor current, differences between maximum and minimum values of spin motor current, changes in the time-derivative (time-rates of change) of spin motor current or other changes in time-profiles of spin motor current or combinations or indicators thereof. These approaches to detecting HDI provide several potential advantages. Detection of HDI can be achieved relatively early in a test or other procedure, can be performed relatively rapidly, can distinguish HDI from at least some other anomalies and can indicate the location and/or magnitude of HDI occurrences.

Head-disk interference detection using spin motor current

An adapter which allows two or more hard disk drives to conduct self-testing in a single test rack slot is provided. Testing can be individually controlled for the various HDDs in a slot. Peltier cell devices or other cooling or heating devices can be controlled to achieve individualized temperature control for HDDs in the test rack slot.

Test rack adapter for hard disk drive

A magneto-optical clock head is disclosed. The magneto-optical clock head allows a longitudinally recorded clock track to be read from a disk surface from a position outside of a head-disk assembly (HDA). The clock track has sections of alternating magnetization which define transitions. Importantly, the magneto-optical clock head is used to sense the transitions using the transverse Kerr effect, as opposed to the longitudinal Kerr effect as used in one prior technique. In one embodiment, the magneto-optical clock head includes a light source for generating a p-polarized beam which is aligned in such a manner that it strikes the clock track. A reflected beam is then produced which has an intensity that varies based upon the direction of the magnetization of the sections of alternating magnetization of the clock track due to the transverse Kerr effect. A detector is provided to detect the intensity variations in the reflected beam and to ultimately generate a clock signal which is provided to transducers to allow them to appropriately write servo information onto their respective disk surfaces. A method for optically reading a clock signal stored within a clock track which is written onto a disk surface that is located within a head disk assembly of a disk drive is also provided.

Method and apparatus for reading a clock track with a magneto-optical clock head using the transverse Kerr effect

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Longmont, CO, United States of America

Richard LeSage