Patterned media magnetic recording disk drive with write clock phase adjustment for write head track misregistration
a magnetic recording disk and write clock technology, applied in the direction of magnetic recording, data recording, instruments, etc., can solve problems such as write errors on selected tracks
Active Publication Date: 2010-12-09
WESTERN DIGITAL TECH INC
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Benefits of technology
The invention is about a magnetic recording disk drive that compensates for misregistration of the write head. The drive has a read head and a write head, and there is a known offset between them. This offset causes the read head to align with one data track while the write head aligns with another track. As the disk rotates, the read head detects servo sectors and generates a position error signal to keep it on track. The read head also detects synchronization marks to control the write clock so that data can be written synchronized with the read head. The write head produces a magnetic write field within a write bubble, and if the write head is shifted, the center of a data island passes through the boundary of the write bubble sooner, causing an effective shift in the timing of when the center passes through. The disk drive compensates for this shift by adjusting the phase of the write clock. This adjustment uses a lookup table or an equation generated by a curve-fitting algorithm. The technical effect of the invention is to improve the accuracy of writing data on the disk drive.
Problems solved by technology
This may lead to write errors on the selected track.
Method used
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Embodiment Construction
[0018]FIG. 1 is a top view of a patterned-media disk drive 100 like that to which the present invention relates. The drive 100 has a housing or base 101 that supports an actuator 130 and a spindle motor (not shown) for rotating the patterned-media magnetic recording disk 10 about its center 13. The actuator 130 may be a voice coil motor (VCM) rotary actuator that has a rigid arm 134 and rotates about pivot 132 as shown by arrow 124. A head-suspension assembly includes a suspension 121 that has one end attached to the end of actuator arm 134 and a head carrier, such as an air-bearing slider 122, attached to the other end of suspension 121. The suspension 121 permits the head carrier 122 to be maintained very close to the surface of disk 10. The slider 122 supports the read / write or recording head 109. The recording head 109 is typically a combination of an inductive write head with a magnetoresistive read head (also called a read / write head) and is located on the trailing end or end ...
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| Property | Measurement | Unit |
|---|---|---|
| magnetic write field | aaaaa | aaaaa |
| phase | aaaaa | aaaaa |
| TMR phase | aaaaa | aaaaa |
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Abstract
A patterned-media magnetic recording disk drive has compensation for write head track misregistration (TMR) from the track centerline. As the disk rotates, the read head detects angularly spaced servo sectors and generates a position error signal (PES) which is used by the servo control system to maintain the read head on track. As the disk rotates, the read head also detects angularly spaced synchronization marks, which are used to control the write clock so that magnetization reversal of the magnetic write field from the write head is synchronized with the position of the data islands. If there is TMR of the write head, there will be an effective shift of A(p in the timing of when the center of the data islands pass through the write field. The disk drive includes write clock phase adjustment circuitry that correlates the PES with Δφ to compensate for TMR of the write head.
Description
BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]This invention relates generally to magnetic recording disk drives for use with patterned media, wherein each data bit is stored in a magnetically isolated block or island on the disk, and more particularly to such a disk drive with an improved clock for writing the data.[0003]2. Description of the Related Art[0004]Magnetic recording hard disk drives with patterned magnetic recording media have been proposed to increase the data density. In patterned media, the magnetic material on the disk is patterned into small isolated data blocks or islands arranged in concentric data tracks. Each island contains a single magnetic “bit” and is separated from neighboring islands by a nonmagnetic region. This is in contrast to conventional continuous media wherein a single “bit” is composed of multiple weakly-coupled neighboring magnetic grains that form a single magnetic domain and the bits are physically adjacent to one another. Pa...
Claims
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IPC IPC(8): G11B21/02
CPCB82Y10/00G11B5/743G11B5/59627
InventorALBRECHT, THOMAS R.SCHABES, MANFRED ERNST
OwnerWESTERN DIGITAL TECH INC