Magnetic Head Fly Amount Control for Self-Servo Write Accuracy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In magnetic disk devices, accurately positioning the magnetic head for self-servo writes is challenging due to the absence of a positioning pattern on the recording surface, making it difficult to set the fly amount of the magnetic head to an appropriate state for accurate writing.
Innovation Solution
A magnetic disk device with a controller that detects optimal fly amounts and distributions, adjusts the magnetic head's protrusion, and moves it to specified positions to write spiral servo patterns, ensuring accurate positioning and fly height control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If touchdown processing is performed only at the innermost position, then the magnetic head can be positioned accurately at that location, but the fly amount cannot be set appropriately at other positions
Solution Approach 1:
The patent performs preliminary touchdown processing at the innermost position to establish a reference fly amount. This reference value is then used to determine appropriate fly amounts at other radial positions, enabling accurate positioning and fly height control across the entire disk without requiring touchdown at every position.
Solution Approach 2:
The patent changes the fly amount parameter dynamically based on the radial position of the magnetic head. By adjusting the fly amount according to the distance from the innermost position, the system maintains optimal spacing between the magnetic head and recording surface across different tracks.
2Ease of manufacture
If no positioning pattern exists on the recording surface, then the magnetic disk can be manufactured with simpler structure, but accurate positioning and tracking become difficult
Solution Approach 1:
The magnetic head uses its own position detection capabilities and the reference fly amount established during initial touchdown to autonomously position itself accurately at various radial positions without requiring external positioning patterns or markers on the disk surface.
Data Source
AI summary
According to one embodiment, a magnetic disk device detects a first optimal fly amount, estimates a first optimal fly amount distribution, obtains a movable distance and an optimal moving speed of a magnetic head, detects a second optimal fly amount, moves the magnetic head to a plurality of movement positions specified based on the movable distance and the optimal moving speed while sequentially positioning thereat, and writes a plurality of spiral servo patterns to a magnetic disk while controlling the amount of protrusion of the magnetic head so that the spacing between the magnetic head at each of the movement positions and the magnetic disk becomes the first and second optimal fly amounts.