Maxtor Corporation

Seagate Technology Incorporated

David Scott McMurtrey

Richard LeSage

Steven W Meeks

Brian P Rigney

Paul F Dunn

Peter R Svendsen

Jason Laks

William M Marvin, Jr

Richard Dennis Lesage

W Craig Tomalty

An apparatus is provided for writing reference patterns on a data storage disk of a disk drive. The disk is rotated by a spindle motor. A back EMF sense circuit generates a sequence of zero crossing signals from back EMF sensed on windings of the spindle motor over each revolution of the spindle motor. The sequence of zero crossing signals define a corresponding sequence of zero crossing periods of time between successive zero crossing signals. A Phase Locked Loop (PLL) circuit generates a timing signal in response to comparison of a feedback signal to the zero crossing signals. The PLL circuit also compensates for repeatable variation among the sequence of zero crossing periods over each revolution of the spindle motor so that the timing signal is substantially independent of the repeatable variation among the sequence of zero crossing periods. A recording pattern generator writes reference patterns on the disk in response to the timing signal as the disk is rotated by the spindle motor. Related methods of making a disk drive are also provided.

Writing reference patterns in a disk drive using back EMF based timing signals compensated for repeatable variation therein

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

The present disclosure is directed to systems and methods of rewriting defective tracks in a data storage device. In a particular embodiment, the method includes writing a servo pattern on a data storage surface having tracks, detecting a defective track, and rewriting information on the defective track. The method also includes failing a test when a number of defective tracks is greater than a threshold. The method also includes rewriting servo bursts.

System and method of rewriting data tracks

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

Provided is a disk drive with a disk and an actuator assembly on which a communication device is mounted for communication with the disk. Position information read from the disk is processed through a channel that generates an analog position error signal that is then converted to a digital position error signal by a first signal converter. Based on the digital position error signal, a controller determines whether realignment of the communication device with the disk is required. The operation of the first signal converter is only periodically required. When realignment is required, then a digital position control signal is generated by the controller and is then converted to an analog position control signal by a second signal converter, which shares circuitry with the first signal converter. Normally, the second signal converter is operating to realign the communication device. Therefore, the shared circuitry is normally operating as part of the second signal converter. Operation of the shared circuitry between the first signal converter and the second signal converter is switched by a switch controlled by the controller. Based on the analog position control signal, a servo system causes the actuator assembly to reposition the communication device for fine adjustment to maintain proper alignment with the disk.

Disk drive system which uses a common DAC for digital positioning

An apparatus and method for torque disturbance precompensation in a disk drive spindle motor includes an amplifier for providing current to the spindle motor in response to an input signal. A velocity detector determines the velocity of the motor, which is then compared to a predetermined velocity to generate an error signal. Compensator elements of the control loop develop an actuating signal from the error signal. The actuating signal is then summed with a torque correction value provided by a look-up table. The torque correction value precompensates the motor by causing the amplifier to provide an additional incremented current to the motor. The additional current corrects the torque disturbance resulting from the movement of the heads across the disk.

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Loveland, CO, United States of America

David Scott McMurtrey