Patterned Media Disk Sync Marks for Head Offset Compensation
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Solution Overview
Problem
Magnetic recording hard disk drives with patterned media face challenges in writing data to tracks near zone boundaries due to effective radial offsets between the read and write heads, causing misalignment and differing write frequencies required for each zone.
Innovation Solution
The implementation of patterned-media disks with annular data zones featuring radially-directed synchronization marks that extend into nondata regions, allowing the read head to synchronize the write head with data islands despite radial offsets, and strategically placing annular nondata regions near zone perimeters to accommodate these offsets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If data zones are arranged with different angular frequencies to achieve approximately equal linear pitch across zones, then data density is improved, but write head synchronization becomes problematic near zone boundaries due to radial offsets between read and write heads
Solution Approach 1:
A nondata region is introduced as an intermediary zone between data zones, containing sync marks that extend radially across the nondata region. This mediator allows the read head to detect synchronization signals even when positioned in the nondata region, enabling the write head to maintain proper synchronization with data islands despite radial offsets that occur near zone boundaries
Solution Approach 2:
Sync marks are pre-positioned in the nondata regions adjacent to data zones before data writing operations commence. These预先 placed sync marks provide reference signals that enable the write head to establish and maintain correct timing and frequency synchronization before actual data writing begins in each zone
2Device complexity
If read head and write head are positioned on the same slider to reduce complexity, then device complexity is reduced, but effective radial offset causes misalignment near zone boundaries
Solution Approach 1:
The nondata region with extending sync marks serves as a mediator that bridges the radial offset between read and write heads. By detecting sync marks in the nondata region, the read head provides reference information that compensates for the radial misalignment, allowing synchronized operation of co-located read and write heads without requiring separate positioning mechanisms
Data Source
AI summary
A patterned-media magnetic recording disk has data islands arranged into concentric data tracks and the data tracks arranged into radially-spaced annular zones, with each zone having an inside-diameter (ID) perimeter and an outside-diameter (OD) perimeter and at least one annular nondata region near one of its perimeters. Each zone includes generally radially-directed synchronization (sync) marks that extend from the zone ID perimeter to the zone OD perimeter so as to extend into the annular nondata region or regions of the zone. In the disk drive that uses the patterned-media disks the read head and write head have an effective radial offset relative to one another, so the write head may be on a data track near a zone perimeter when the read head is located in a nondata region. The read head detects the sync marks that extend into the nondata region so that the write head can be synchronized with the data islands in the data track.