Zone-Servo Disk Writing at Boundaries With Timing Correction
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Solution Overview
Problem
The existing disk devices with zone servo systems face challenges in improving format efficiency at zone boundary areas due to the mixture of servo patterns written at different frequencies, leading to inefficiencies in data storage capacity.
Innovation Solution
The disk device is configured to write one servo pattern at a boundary area and another servo pattern circumferentially shifted, with timing correction data generated to adjust write start timings, reducing the circumferential gaps between patterns and optimizing the format efficiency by using a controller to manage servo patterns and timing corrections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If servo patterns are written at different frequencies for different zones, then write frequency is optimized for each zone, but circumferential gaps increase at zone boundary areas
Solution Approach 1:
The controller performs preliminary timing correction by calculating and applying a timing correction amount before writing servo patterns at zone boundaries. This advance adjustment ensures that the write start timing of the second servo pattern is corrected to reduce circumferential gaps, allowing the system to maintain different write frequencies for different zones while minimizing the harmful gaps at boundaries.
2Adaptability or versatility
If mixture of servo patterns with different frequencies is written at zone boundary, then zone servo system functionality is maintained, but format efficiency decreases
Solution Approach 1:
The patent applies local quality by implementing timing correction specifically at zone boundary areas where the contradiction occurs, while maintaining different write frequencies for different zones. The controller calculates a timing correction amount based on the radial position and applies it only to servo patterns written at or near zone boundaries, allowing the system to maintain zone servo functionality while improving format efficiency locally at the problematic boundary regions.
3Productivity
If timing correction is applied to reduce circumferential gaps, then format efficiency improves, but device complexity increases
Solution Approach 1:
The controller changes the timing parameter of servo pattern writing by calculating and applying a timing correction amount. This parameter change allows the system to reduce circumferential gaps at zone boundaries while maintaining the overall zone servo structure. The timing correction is calculated based on the radial position and the difference in write frequencies between adjacent zones, providing a systematic way to improve format efficiency without requiring fundamental changes to the device architecture.
Data Source
AI summary
According to one embodiment, there is provided a disk device including a head, a disk medium and a controller. The disk medium includes multiple zones concentrically provided. The controller, when two servo patterns corresponding to two adjacent zones are written by the head on a track of a boundary area between the two adjacent zones of the multiple zones, generates timing correction data according to a radial position of the boundary area. The controller writes one servo pattern of the two servo patterns on the track of the boundary area. The controller writes the other servo pattern of the two servo patterns, at a position circumferentially shifted from the one servo pattern in the track of the boundary area, according to the timing correction data.