Magnetic Disk Head Positioning via Dual Read Head Error Correction
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Solution Overview
Problem
Magnetic disk devices face challenges in accurately detecting and correcting track pitch errors in Two-Dimensional Magnetic Recording systems, which affect the precision of head positioning and data reading/writing processes.
Innovation Solution
A magnetic disk device with a head assembly including a write head and two read heads, where the device detects track pitch errors using a method that involves writing a servo pattern based on correction values to correct these errors, allowing for precise head positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single read head is used to detect track pitch error, then the device complexity is low, but the measurement precision of track pitch error is insufficient
Solution Approach 1:
The read head is divided into two separate read heads (first read head and second read head) positioned at different radial locations. Each read head independently detects signals from different tracks, enabling more precise measurement of track pitch error through comparison of the detected signals.
Solution Approach 2:
A correction value is introduced as an intermediary element that compensates for track pitch errors. The correction value is calculated based on the difference in detected signals from the two read heads and is used to adjust the positioning of the write head, thereby eliminating the measurement precision limitation.
2Manufacturing precision
If traditional head positioning method is used, then the device complexity is low, but the manufacturing precision of track positioning is insufficient
Solution Approach 1:
The system implements a feedback mechanism where the signals detected by the two read heads are compared, and the difference is used to calculate a correction value. This correction value is fed back to adjust the position of the write head, creating a closed-loop control system that continuously improves positioning accuracy.
Solution Approach 2:
Before the write head performs the actual writing operation, the system预先 detects the track pitch error using the two read heads and calculates the correction value. This preliminary detection and correction process ensures that the write head is positioned with high precision before data writing begins.
3Reliability
If track pitch error is not corrected, then the processing time is short, but the reliability of data reading and writing is low
Solution Approach 1:
The system performs track pitch error detection and correction value calculation before the actual data reading and writing operations. By completing the correction process in advance, the system ensures high reliability of subsequent data operations without significantly increasing the overall processing time.
Solution Approach 2:
The system uses its own read heads to detect and measure the track pitch error, and then uses this information to self-correct the positioning. This self-service approach eliminates the need for external calibration equipment and reduces the time required for reliability improvement.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enhances the accuracy of read/write operations by effectively detecting and correcting track pitch errors, thereby improving data storage precision and reducing processing time.
Implementation Method 1
a write head configured to write data on the disk
Implementation Method 2
a first read head, and a second read head each configured to read data from the disk
Data Source
AI summary
According to one embodiment, a magnetic disk device includes a disk, a head including a write head configured to write data on the disk, a first read head, and a second read head each configured to read data from the disk, and a controller configured to detect a first error of each track pitch corresponding to each track of the disk on the basis of a first gap in a radial direction between the first read head and the second read head at each position in the radial direction of the disk, write a servo pattern on the disk on the basis of a first correction value used to correct the first error, and position the head on the basis of the servo pattern.