Bit Patterned Media Write Timing Synchronization
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Solution Overview
Problem
In disk drives with bit patterned media, the offset between the read head and write head creates inconsistencies in pattern regularity, making it challenging to synchronize the write signal with the patterns on the write track, as conventional solutions rely on look-up tables that require memory storage and reading processes.
Innovation Solution
The method involves positioning the read head at a read-write offset with respect to the write head, writing data on a write track, providing a timing offset between the write and servoing tracks, storing this offset in sync fields within servo sectors, and synchronizing the write signal using the read-back timing offset without memory storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If look-up tables are used to store timing offset information, then synchronization accuracy is improved, but memory storage requirements and access time increase
Solution Approach 1:
The patent extracts the timing offset information from the look-up table storage method and embeds it directly into the servo data structure on the disk medium. This allows the timing offset to be read directly during normal servo operations without requiring separate memory access, thereby eliminating the time penalty while preserving synchronization accuracy.
Solution Approach 2:
The patent merges the timing offset information with the existing servo sector data structure by storing it in the sync field. This consolidation allows the timing offset to be retrieved simultaneously with other servo information during regular track following operations, eliminating the need for separate memory access operations.
2Measurement precision
If look-up tables are used to store timing offset information, then synchronization accuracy is improved, but device complexity increases
Solution Approach 1:
The patent combines the timing offset storage with the existing servo sector structure on the disk. By utilizing the sync field that is already part of the servo data format, the system eliminates the need for separate look-up table memory structures, reducing device complexity while maintaining synchronization capability.
Solution Approach 2:
The servo sectors on the disk medium serve their own synchronization function by containing the timing offset information within their own structure. This self-contained approach eliminates the need for external memory storage and complex data retrieval mechanisms, simplifying the overall system architecture.
Data Source
AI summary
A system and method of establishing write timing in a disk drive using bit patterned media and a magnetic head with read-write offset in which servoing and writing occur on different tracks with timing offsets. Initially, the distance between the servoing and writing tracks is determined for each track/head position in accordance with head geometry and skew angle. The relative timing errors are then measured by iteratively writing data at timing offset increments to determine the optimal timing offset for the servoing/writing track pair, and then writing the offset to sync fields on the servoing tracks of the disk.