Magnetic Disk Head Position Correction via RRO Segmentation
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Solution Overview
Problem
Magnetic disk devices face challenges in accurately correcting head position due to repeatable runout (RRO) errors, which affect data recording and reading precision, particularly in maintaining track center alignment across the disk surface.
Innovation Solution
A magnetic disk device and method that involves acquiring correction data for RRO at multiple measurement positions based on linearity errors and Lissajous waveforms, using a controller to adjust head positioning through RRO learning units and position correctors, thereby improving servo positioning accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If RRO correction is performed at multiple measurement positions, then positioning accuracy is improved, but measurement and correction complexity increases
Solution Approach 1:
The patent divides the disk surface into multiple measurement positions in the radial direction and performs RRO correction separately at each position. By segmenting the correction process into discrete radial positions, the system achieves comprehensive coverage of RRO variations while maintaining manageable complexity through systematic processing of each segment.
Solution Approach 2:
The patent introduces interpolation in the radial dimension to extend correction from discrete measurement positions to continuous radial coverage. By measuring at specific radial positions and interpolating between them, the system achieves accurate correction across the entire radial dimension without requiring measurements at every possible position.
2Measurement precision
If measurement positions are appropriately set for RRO correction, then correction accuracy is improved, but setup and configuration complexity increases
Solution Approach 1:
The patent performs RRO measurement and correction setup during the manufacturing or initialization phase, before actual data operations. By pre-measuring RRO characteristics at multiple radial positions and establishing correction parameters in advance, the system eliminates the need for complex real-time configuration while ensuring high correction accuracy during normal operation.
Solution Approach 2:
The system automatically determines optimal measurement positions and performs interpolation calculations without requiring manual configuration. The correction mechanism self-adjusts based on pre-acquired RRO data, reducing operational complexity while maintaining high accuracy through automated position selection and interpolation.
Data Source
AI summary
According to one embodiment, a magnetic disk device includes a disk including a recording region including a servo sector, a head configured to write data to the disk and read data from the disk, and a controller configured to acquire a plurality of correction data for a repeatable runout of the recording region, the correction data respectively corresponding to a plurality of measurement positions set based on a first linearity error acquired by reading the servo sector, and to correct a position of the head based on the correction data.