Patterned Media Servo Zones with Overlap Transitions
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Solution Overview
Problem
Existing servo writing techniques face challenges in writing servo data across servo zone boundaries on patterned magnetic disks, particularly in maintaining uniformity and compatibility with planarization constraints, which affects the alignment and accuracy of slider positioning over the disk.
Innovation Solution
The implementation of a zoned servo architecture with alternating series of concentric servo zones and overlap zones, where overlap zones are dual frequency zones or bootstrap zones, allowing for robust servo writing by accommodating varying servo frequencies and complying with planarization constraints through radial overlap lengths and extended sync patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a zoned servo architecture with alternating servo zones and overlap zones is implemented, then servo data writing accuracy across zone boundaries is improved, but device complexity increases due to dual frequency zones and bootstrap zones
Solution Approach 1:
The disk surface is segmented into multiple servo zones with different servo frequencies, separated by overlap zones. Each servo zone is independently configured with specific servo patterns, allowing precise control of servo data writing in different radial regions while maintaining overall system accuracy.
Solution Approach 2:
Overlap zones act as intermediary regions between adjacent servo zones of different frequencies. These zones contain both lower frequency and higher frequency servo patterns, serving as transition areas that enable accurate servo data writing when the write head moves between zones of different servo frequencies.
2Reliability
If radial overlap length is increased to accommodate RWO variations, then slider positioning reliability is improved, but data capacity is reduced due to loss of usable track space
Solution Approach 1:
The radial overlap length is not uniformly applied across the entire disk but is specifically configured in overlap zones where needed for transitioning between servo frequencies. This localized approach ensures reliable slider positioning during zone transitions while minimizing the impact on overall data capacity in non-overlap regions.
Solution Approach 2:
The servo frequency is dynamically adjusted based on the radial position of the write head. As the write head moves between servo zones, the system transitions between different servo frequencies, allowing optimal servo performance at each radial location while accommodating RWO variations without uniformly reducing data capacity.
3Quantity of substance
If servo frequency is increased to reduce circumferential width of servo sectors, then data capacity is improved, but manufacturing precision deteriorates due to planarization constraint violations
Solution Approach 1:
The disk is divided into multiple servo zones, each operating at a different servo frequency. This segmentation allows high servo frequencies to be used in outer regions where circumferential width is naturally smaller, while lower frequencies are used in inner regions, maintaining planarization compliance throughout without sacrificing overall data capacity.
Solution Approach 2:
The servo frequency parameter is changed across different radial zones rather than using a single frequency throughout. This parameter change allows the system to optimize data capacity in each zone while maintaining compliance with planarization constraints, as each zone's servo frequency is selected to match its specific geometric and manufacturing requirements.
Data Source
AI summary
Embodiments described herein provide for patterned media concentric zones with an alternating series of concentric servo zones and overlap zones. The overlap zones facilitate the writing of servo data between servo zones of different servo frequency. The overlap zones may be dual frequency zones. The dual frequency zones have a first set of overlap patterns with the substantially identical pattern as the bordering lower frequency servo zone and a second set of overlap patterns with the substantially identical pattern as the bordering higher frequency servo zone. A bootstrap zone can be included near the inner diameter to assist initial servo writing. Alternatively the overlap zones are bootstrap zones. Such bootstrap zones have both bootstrap patterns and overlap patterns, the overlap patterns have the substantially identical pattern as a bordering servo zone. Bootstrap patterns only require DC magnetization for servo operability.