Magnetic Disk Read Head Positioning for Offset Compensation
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Solution Overview
Problem
Magnetic disk devices face challenges in accurately reading data due to offset issues between the write and read heads, leading to inefficiencies in data retrieval and potential errors.
Innovation Solution
A magnetic disk device is configured with a control unit that includes a read processing unit, a comparison unit, and a determination unit. This unit executes read processing by moving the read head to multiple radial positions, compares signal qualities, and determines an appropriate read position for optimal data reading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the read head is positioned at a fixed radial offset from the write head, then the device structure is simple, but reading accuracy deteriorates due to head offset variations
Solution Approach 1:
The patent implements dynamic adjustment of the read head's radial position based on the write head's position. The read head can be independently moved in the radial direction to match the optimal reading position for each track, rather than maintaining a fixed offset. This dynamic positioning resolves the contradiction by adapting the read head position to compensate for head offset variations, thereby improving reading accuracy without requiring complex permanent structural modifications
Solution Approach 2:
The system uses feedback from the write head's position information to control the read head's radial position. By monitoring the write head position and adjusting the read head accordingly, the system ensures accurate data reading despite variations in head alignment. This feedback mechanism allows the read head to automatically compensate for offset variations, improving reading accuracy while maintaining relatively simple device structure
2Measurement precision
If the read head is moved to multiple radial positions to find the optimal reading position, then reading accuracy is improved, but the time required for data retrieval increases
Solution Approach 1:
The system performs preliminary positioning of the read head to the expected optimal radial position based on the write head's position information before actual reading begins. This preliminary action uses the known relationship between write and read head positions to pre-position the read head, avoiding the need to search through multiple radial positions during data retrieval, thus improving reading accuracy while minimizing time loss
Solution Approach 2:
The patent replaces mechanical searching through multiple radial positions with a control-based positioning system. Instead of physically moving the read head through multiple positions to find the optimal one, the system uses control signals to directly position the read head at the calculated optimal position based on write head position data, thereby achieving accurate reading without time-consuming mechanical search
3Measurement precision
If the read head position is dynamically adjusted for each track, then reading accuracy is improved, but the control system complexity increases
Solution Approach 1:
The control system is designed to serve multiple functions: it tracks the write head position, calculates the optimal read head position, and controls the read head movement. By making the control system multi-functional, the patent avoids adding separate dedicated systems for each function, thereby improving reading accuracy through dynamic positioning while keeping the overall control system complexity manageable through functional integration
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
The solution enables efficient data reading by identifying the radial position that yields the highest signal quality, thereby improving data retrieval accuracy and reducing errors.
Implementation Method 1
a read head that reads data from the recording layer of the disk
Data Source
AI summary
According to one embodiment, a magnetic disk device includes a disk, a read head, and a control unit. The control unit includes a read processing unit that executes first read processing of moving the read head to n1 radial positions within a period in which the disk makes m1 rotations and reading the data of the track, a comparison unit that derives a first signal of highest quality, and a determination unit that determines a radial position at which the first signal of the highest quality is derived as a first appropriate read position. Where 1≤m1<n1.