Magnetic Head Offset Correction for Write-Induced RRO Errors
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing magnetic disk apparatuses face challenges in accurately positioning the magnetic head due to repeatable run-out (RRO) errors, which worsen during write operations, leading to increased position errors and reduced storage capacity.
Innovation Solution
The apparatus employs a correction algorithm that adjusts the burst demodulated values during write operations to match those of non-write operations, using correction setting information to minimize RRO errors, thereby improving head positioning accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the magnetic disk apparatus uses conventional positioning methods, then the head can be positioned on tracks, but position errors increase during write operations due to RRO errors
Solution Approach 1:
The patent applies parameter changes by adjusting the burst demodulated values through correction algorithms. Specifically, the system changes the parameters of the servo data processing by applying correction values to the burst demodulated values, which modifies the positioning calculations to compensate for RRO errors that occur during write operations, thereby maintaining positioning accuracy despite the operational state changes
Solution Approach 2:
The patent implements feedback by using correction setting information that is generated based on the difference between write and non-write operation states. The system continuously compares the actual head position with the expected position and applies corrective feedback through the correction algorithm to minimize position errors, creating a closed-loop control system that adapts to operational conditions
2Productivity
If the magnetic disk apparatus performs write operations with conventional positioning, then data can be written, but storage capacity is reduced due to increased position errors
Solution Approach 1:
By changing the parameters of the positioning calculation through correction algorithms applied to burst demodulated values, the system maintains accurate head positioning during write operations. This allows the magnetic disk apparatus to utilize the full available storage capacity without needing to allocate extra space for positioning errors, thereby maximizing productivity
3Measurement precision
If the magnetic disk apparatus uses simple positioning methods, then the system complexity is low, but positioning accuracy deteriorates during write operations
Solution Approach 1:
The patent introduces an intermediary element in the form of correction setting information and correction algorithms that act as mediators between the simple burst demodulation process and the final positioning calculation. This intermediary layer processes the raw servo data to compensate for RRO errors without requiring complete redesign of the positioning system, thus improving accuracy while adding only moderate complexity
Solution Approach 2:
The system performs preliminary action by pre-calculating correction values and storing them as correction setting information. These correction values are computed in advance based on the difference between write and non-write operation characteristics, and then applied during actual operations to eliminate positioning errors without requiring complex real-time calculations
Data Source
AI summary
According to one embodiment, a controller of a magnetic disk apparatus operates in a first operation of writing to data regions on a magnetic disk of the magnetic disk apparatus while positioning a magnetic head. In the first operation, the controller demodulates burst patterns to obtain a first burst demodulated value set and corrects the first burst demodulated value set to obtain a second burst demodulated value set. The first burst demodulated value set is corrected on the basis of a correction algorithm using a first set value as an argument. The controller calculates, on the basis of the second burst demodulated value set, an offset amount of the magnetic head from one of servo tracks on the magnetic disk.