Hitachi Global Storage Technologies Netherlands B.v.

Maxtor Corporation

Youping Deng

Lin Guo

Jing Zhang

Randall George Simmons

Wing Tsang Tang

Mike Wang

Christopher Dana Keener

Terry Farren

Huiping Yang

Jinsong Wang

A method and apparatus for detecting predetermined surface characteristics in head gimbal assemblies to improve hard disk drive reliability. The predetermined surface characteristics include head slider protrusions such as scratches or contamination that can cause damage to the head or disk in hard drives. By detecting these protrusions, those drives with an increased chance of failure can be removed from a test group, thereby increasing the quality and reliability of the remaining disk drives. The invention provides a method of detecting these protrusions that is a more practical option than using a scanning electron microscope (SEM) to inspect each head slider.

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

A triple track test for determining respective erase band widths associated with a read/write head involves writing first and second data tracks in each direction and at a certain distance from an origin, and erasing a track having a center at the origin. Based on a triple track test profile (3T) corresponding to the three tracks, a first distance is measured in one direction from the origin to one of the modified data tracks and a first erase band width is computed based thereon. The other side erase band width is computable similarly. A side erase amplitude loss measurement procedure, for determining the amount of signal amplitude lost by an adjacent track due to the respective erase bands, involves constructing a side-erase profile based on a composite of the 3T profile and a full-track profile, from which respective amplitude losses are computed for the respective erase bands.

Triple track test for side erase band width and side erase amplitude loss of a recording head

A method for testing a hard disk drive is described. The method includes determining a number of defects associated with a portion of recordable media associated with a hard disk drive. The method further includes comparing the number of determined defects to a threshold number of defects and provided the number of determined defects is greater than the threshold number of defects, determining that the portion of the disk comprises disk defects.

Media defect removal in disk drive head testing

A method for improving yields in manufacturing processes includes identifying parameters which affect performance at a subsequent step in the process, collecting data concerning individual performance parameters, creating a reference scale which correlates individual parameters with probability of failure at a subsequent step in the process, testing a manufactured unit to collect performance data concerning two or more of the individual parameters from a manufactured unit, comparing performance data concerning two or more of the individual parameters from the manufactured unit to the reference scale to assign probability of failure for each of the single performance parameters, calculating a Figure of Merit, and utilizing the Figure of Merit to sort or disposition units.

Yield/quality improvement using calculated failure rate derived from multiple component level parameters

The present invention is directed to utilizing the capabilities of multi-stage actuators in disk drives to do self servo writing on the disk surfaces, thereby avoiding the use of a servo track writer. In one embodiment, a crash stop that limits the range of motion of a primary actuator is used as an initial reference point for a secondary actuator associated with a first head to position the first head to write a first servo track on a first disk surface. The first servo track is subsequently used as a reference point for a secondary actuator associated with a second head to position the second head for writing one or more servo tracks on a second disk surface. One of these servo tracks on the second disk surface is then used as the reference point relative to which the primary and/or secondary actuator associated with the first head moves the first head to write one or more servo tracks on the first disk surface. This process of alternatingly using the servo tracks written by one head as the reference point relative to which the primary and/or secondary actuators move the other head to write further servo tracks is repeated until all of the desired servo tracks are written.

Disk drive with self servo writing capability

The present invention is directed to utilizing the capabilities of multi-stage actuators in disk drives to write servo tracks that have a variable number of tracks-per-inch (TPI) from head to head, thereby improving both the performance of the drive and manufacturing yields. An appropriate TPI for a particular head has been found to depend on a number of factors that vary from head to head. Consequently, the initial step is to determine an appropriate TPI for at least one of the heads or, more preferably, all of the heads in the drive. The determination typically involves measurements such as read and write width measurements and off-track performance tests for the relevant heads. Once an appropriate TPI format has been determined, the servo tracks are written according to the TPI formats using either a servo track writer or self servo track writing.

Disk drive with variable TPI servo tracks

The present invention is directed to a disk drive that utilizes a multi-stage actuator associated with two or more heads that are each associated with a separate disk surface to realize high speed data transfers. In one embodiment, the multi-stage actuator is used to simultaneously transfer portions of a data file between the heads and the associated disk surfaces and to perform simultaneous seek operations for the heads between data transfer operations. In another embodiment, the multi-stage actuator is used to alternatingly transfer portions of a data file between the heads and the associated disk surfaces and to perform alternating seek operations for the heads such that one head is transferring data while another head is performing a seek operation.

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Sunnyvale, CA, United States of America

Youping Deng