Magnetic Disk Linearity Error Correction via Servo Data Segmentation
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Solution Overview
Problem
Magnetic disk devices face challenges in accurately correcting linearity errors caused by repeatable run out (RRO) errors, which affect the positioning of heads on disk surfaces, leading to inefficiencies in data reading and writing processes.
Innovation Solution
A magnetic disk device with a controller that demodulates servo data, divides it into regions, and performs linearity correction using parameters calculated from demodulation signals to adjust the head position, improving the accuracy of RRO corrections and reducing linearity errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If RRO correction is performed using interpolated data from multiple measurement positions, then head positioning accuracy is improved, but linearity errors increase
Solution Approach 1:
The patent divides the measurement range into multiple division regions and performs linearity correction independently in each region. By segmenting the correction process into radial regions and circumferential regions, the system can address linearity errors locally without compromising overall positioning accuracy. This segmentation allows for more precise correction parameters to be applied in each specific region, resolving the contradiction between interpolation accuracy and linearity errors.
Solution Approach 2:
The patent applies different correction parameters to different division regions based on their specific characteristics. Instead of using a uniform correction approach, the system calculates and applies region-specific correction values that account for local linearity variations. This local quality approach ensures that each region receives the appropriate correction level, improving overall positioning accuracy while maintaining linearity across the entire disk surface.
2Manufacturing precision
If linearity correction parameters are calculated for each division region, then linearity error correction is improved, but device complexity increases
Solution Approach 1:
The patent segments the correction calculation into manageable division regions, where each region has its own correction parameters. This segmentation reduces the overall complexity by breaking down the large-scale correction problem into smaller, more tractable sub-problems. Each division region can be processed independently, making the calculation more efficient and the device implementation more feasible.
Solution Approach 2:
The patent applies linearity correction to specific division regions rather than attempting to correct the entire disk surface uniformly. This partial action approach focuses computational resources on the most critical regions where linearity errors have the greatest impact on positioning accuracy, thereby reducing overall device complexity while maintaining effective correction where it matters most.
Data Source
AI summary
According to one embodiment, a magnetic disk device includes a disk including a recording region including servo sectors, a head configured to write data to the disk and read data from the disk, and a controller configured to demodulate a plurality of pieces of demodulation data from servo data read from servo sectors, divide the demodulation data into a plurality of pieces of division data corresponding to division regions, perform linearity correction corresponding to a plurality of pieces of division data in each of the division regions.