Writable Servo Overlap Zones for Disc Memory Alignment
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Solution Overview
Problem
Data storage devices face challenges in efficiently writing user data near zone boundaries on disc storage media due to changes in servo data configurations and eccentricities between zones, leading to misalignment and reduced data integrity.
Innovation Solution
The implementation of writable servo overlap zones and adaptive algorithms that allow for efficient data writing in zipper regions by modulating servo sample rates and using virtual tracks that read servo data from multiple zones, thereby compensating for eccentricity and misalignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional servo data configurations are used with fixed zone boundaries, then servo patterns can be clearly defined within each zone, but misalignment and data integrity issues occur near zone boundaries due to eccentricities and servo pattern frequency changes
Solution Approach 1:
The disc storage medium is divided into multiple servo super zones with overlapping regions. Each servo super zone contains servo patterns with specific frequency characteristics, and the overlap zones allow the transducer head to read servo data from multiple zones simultaneously, enabling seamless transitions and maintaining alignment precision across zone boundaries.
Solution Approach 2:
The patent merges servo patterns from multiple servo super zones into overlap zones. The transducer head reads and combines servo data from adjacent zones during overlap regions, creating a unified servo reference that eliminates misalignment issues at zone boundaries and maintains data integrity throughout the transition regions.
2Ease of manufacture
If zone boundaries are clearly defined with distinct servo patterns, then servo data can be organized by zones, but unusable areas increase near zone boundaries requiring trimming operations
Solution Approach 1:
The patent implements dynamic servo sampling where the transducer head adaptively reads servo patterns from different zones based on its current position. During overlap zones, the system dynamically switches between or combines servo data from multiple zones, allowing full utilization of boundary regions and eliminating the need for static trimming of unusable areas.
Solution Approach 2:
The system changes servo pattern frequency parameters across different servo super zones. By modulating the servo sample rate and frequency characteristics in overlap zones, the patent enables the transducer head to accurately track and read servo data from multiple zones, converting previously unusable boundary regions into productive storage areas.
3Adaptability or versatility
If servo pattern frequency is changed between zones, then adaptive servo control can be achieved for different disc regions, but trajectory errors occur during zone transitions
Solution Approach 1:
The patent implements preliminary servo sampling before zone transitions occur. The transducer head begins reading servo patterns from the upcoming zone in advance during overlap regions, allowing the system to predict and compensate for frequency changes before they affect the main data writing operation, thereby maintaining trajectory accuracy during transitions.
Solution Approach 2:
The system uses feedback from servo pattern readings in overlap zones to continuously adjust the transducer head position and timing. By monitoring servo data from multiple zones and providing real-time feedback during transitions, the patent eliminates trajectory errors that would otherwise result from abrupt frequency changes between zones.
4Ease of operation
If fixed sgate timing is used for data writing, then writing operations are simple to control, but misalignment occurs near zone boundaries due to servo pattern timing variations
Solution Approach 1:
The patent implements dynamic sgate timing adjustment where the sequencer gate timing is adapted based on the transducer head's position relative to zone boundaries. During overlap zones, the system dynamically modifies sgate timing to account for servo pattern frequency changes, maintaining precise data writing alignment without requiring complex manual calibration.
Solution Approach 2:
The system changes sgate timing parameters in response to detected servo pattern frequency variations. By automatically adjusting the timing parameters during overlap zones based on real-time servo data analysis, the patent maintains writing precision across all disc regions while preserving the simplicity of automated control.
Data Source
AI summary
Systems and methods are disclosed for writable servo zone overlap regions on a disc memory. An apparatus may comprise a controller configured to determine a servo gate (sgate) timing for an overlap zone including servo patterns of a first servo super zone and a second servo super zone of a disc memory, the sgate timing based on servo pattern timing for the first servo super zone and the second servo super zone. The controller may initiate writing to the overlap zone based on the sgate timing. The controller may also reduce the impact of servo pattern frequency change between zones by calculating a trajectory error prior to the crossing, and providing 1/X of the trajectory error into a servo feedback loop for a following X servo sampling points.