Hard Disk Write Timing with Sync Marks
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Solution Overview
Problem
Conventional hard disk drives face issues with accurately writing data onto patterned disks due to undesirable jitter and misalignment of data with magnetic dots, caused by the use of conventional sync fields for synchronizing the write clock, leading to weak magnetic fields and potential cross-talk with adjacent dots.
Innovation Solution
A hard disk drive with a patterned disk featuring data fields that include a sync field and multiple sync marks, where the write clock is synchronized by both the sync field and sync marks, allowing for re-synchronization during data writing and minimizing jitter and cross-talk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional sync field is used to synchronize the write clock, then the writing process can be maintained, but undesirable jitter and misalignment of data with magnetic dots occur
Solution Approach 1:
The sync field is segmented into multiple sync marks distributed throughout the data field. This segmentation allows for multiple synchronization points during the writing process, enabling the write clock to be continuously adjusted to maintain precise alignment with magnetic dots while reducing jitter.
Solution Approach 2:
The sync marks provide continuous feedback signals during the writing process. The controller uses these feedback signals to adjust the write clock in real-time, ensuring that data is written at the correct position on the magnetic dots and maintaining high alignment precision throughout the entire data field.
2Productivity
If the sync field is written with the data, then data storage is achieved, but proper alignment of data and dots cannot be guaranteed
Solution Approach 1:
The sync field is divided into multiple discrete sync marks scattered throughout the data field. This allows the data to be written continuously for high productivity while the sync marks provide periodic alignment references to maintain precision, resolving the trade-off between storage efficiency and alignment accuracy.
Solution Approach 2:
The sync marks are pre-positioned at specific locations within the data field before data writing begins. These pre-positioned sync marks serve as predetermined alignment references that guide the writing process, ensuring data is written at the correct positions without requiring post-writing adjustment.
3Speed
If data is written without proper synchronization, then writing speed can be maintained, but weak magnetic fields and cross-talk with adjacent dots occur
Solution Approach 1:
The sync marks provide continuous feedback during high-speed writing to adjust the write clock timing. This feedback mechanism ensures that even at high writing speeds, the magnetic fields are written with sufficient precision and strength to avoid cross-talk with adjacent dots, maintaining both speed and signal integrity.
Solution Approach 2:
The sync marks enable dynamic adjustment of writing parameters such as clock frequency and phase during the writing process. By changing these parameters in response to the sync mark positions, the system maintains optimal writing conditions that prevent weak magnetic fields and cross-talk while preserving high writing speed.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables accurate and aligned data writing onto patterned disks, reducing jitter and cross-talk, and allowing for efficient data storage by using smaller sync marks that do not significantly reduce the data storage area.
Implementation Method 1
The heads write and read information by magnetizing and sensing the magnetic fields of the disk
Implementation Method 2
The heads write and read information by magnetizing and sensing the magnetic fields of the disk
Data Source
AI summary
A hard disk drive with a patterned disk that has a plurality of data fields. Each data field includes a sync field and a plurality of sync marks. Data is written onto the patterned disk in accordance with a write clock. The write clock is generated and synchronized by the sync field and the sync marks. The sync marks are dispersed throughout the data field so that the write clock is resynchronized as data is written onto the field.