Magnetic Disk Servo Pattern Recording via Flying Height Control
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Solution Overview
Problem
The existing manufacturing methods for magnetic disk devices face inefficiencies in accurately recording auxiliary servo patterns on blank magnetic disks due to deviations in estimated and actual reference flying height distributions, leading to poor quality spiral signals and increased recording time.
Innovation Solution
The method involves measuring and recording spiral signals on multiple recording surfaces while controlling flying height using estimated and measured distributions of reference flying heights, ensuring accurate positioning and reducing untracking errors by selecting non-adjacent magnetic heads for each surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the magnetic disk device records auxiliary servo patterns using estimated reference flying height distribution, then the recording process can be initiated, but the quality of spiral signals deteriorates due to deviation between estimated and actual flying height distributions
Solution Approach 1:
The patent applies preliminary action by measuring the actual reference flying height distribution before recording the auxiliary servo pattern. This measurement step is performed in advance to obtain accurate flying height data, which is then used to control the magnetic head clearance during spiral signal recording, ensuring high signal quality from the start.
Solution Approach 2:
The patent implements feedback by using the measured actual reference flying height distribution to adjust and control the magnetic head clearance during the recording process. The system continuously references the measured distribution to maintain optimal flying height, creating a closed-loop control mechanism that ensures accurate spiral signal recording.
2Ease of manufacture
If the magnetic disk device uses estimated reference flying height distribution for recording, then the process can proceed without additional measurements, but the recording time increases due to rework and adjustments
Solution Approach 1:
The patent performs the reference flying height measurement in advance before the recording process begins. This preliminary measurement ensures that accurate flying height data is available from the start, eliminating the need for time-consuming adjustments and rework during recording, thus reducing total recording time while maintaining process simplicity.
Solution Approach 2:
The patent prepares the accurate reference flying height distribution data beforehand to cushion against potential deviations during recording. By having the measured distribution ready in advance, the system prevents time loss that would occur from correcting flying height issues during the actual recording process.
3Device complexity
If adjacent magnetic heads are used for recording on multiple recording surfaces, then the device structure remains simple, but untracking errors increase due to positioning deviations
Solution Approach 1:
The patent applies segmentation by assigning non-adjacent magnetic heads to different recording surfaces. Specifically, magnetic heads are selected such that their positions are separated by at least one recording surface interval, effectively segmenting the head allocation to avoid consecutive heads being used on adjacent surfaces. This segmentation reduces positioning deviations and untracking errors while maintaining relatively simple device structure.
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 approach enhances the recording efficiency and quality of auxiliary servo patterns by minimizing untracking and optimizing the recording process, thereby improving the overall manufacturing efficiency of magnetic disk devices.
Implementation Method 1
recording a plurality of first spiral signals on a first recording surface by using a first magnetic head
Data Source
AI summary
According to an embodiment, a manufacturing method includes: estimating a distribution of an initial value of a clearance of a magnetic head on a first recording surface; and recording first spiral signals on the first recording surface while controlling a clearance using the distribution of the initial value of the estimated clearance. The manufacturing method includes measuring a distribution of an initial value of a clearance of a magnetic head on a second recording surface under positioning control using the first spiral signals recorded on the first recording surface. The manufacturing method includes recording the first spiral signals on the second recording surface while controlling a clearance using the distribution of the initial value of the measured clearance of the magnetic head on the second recording surface. The manufacturing method includes recording the second spiral signals on a third recording surface under positioning control using the first spiral signals recorded on the second recording surface.