Magnetic Head Flying Height Control to Prevent Disk Contact
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Solution Overview
Problem
In magnetic disk devices, achieving high recording density requires a narrow interval between the magnetic disk and the head, but this proximity risks damaging the magnetic head and reducing the device's lifespan due to potential contact.
Innovation Solution
A method and device that adjust the head flying height by using a heater near the head to control the interval, employing a controller to measure and calculate statistical variations in flying height, and adjust the head position based on predefined thresholds to prevent contact and optimize flying height.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the interval between the magnetic disk and the head is reduced to improve recording density, then the recording density is improved, but the risk of head-disk contact increases which may destroy the magnetic head and shorten device lifespan
Solution Approach 1:
The patent implements dynamic adjustment of head flying height through heater control. The system continuously monitors head-disk interval and adjusts the heater power to maintain optimal flying height, enabling the head to adapt to disk surface variations and preventing contact while maintaining narrow interval for high recording density
Solution Approach 2:
The patent employs a feedback control mechanism where the head-disk interval is measured and used to control heater power. The controller receives measurement data, calculates appropriate heater power levels, and adjusts heating accordingly to maintain safe flying height, creating a closed-loop system that prevents head-disk contact while enabling narrow interval operation
2Quantity of substance
If the head flying height is reduced to improve recording density, then the recording density is improved, but the magnetic head may be destroyed due to contact with the magnetic disk
Solution Approach 1:
The patent applies beforehand cushioning by using heater-induced thermal expansion to preemptively increase the head-disk interval when contact risk is detected. The heater creates a protective air bearing gap before contact can occur, cushioning the head from potential damage while maintaining operation at narrow intervals for high recording density
3Measurement precision
If statistical analysis of chronological data is used to detect head flying height variations, then the detection accuracy is improved, but the response time may be delayed due to data processing requirements
Solution Approach 1:
The patent applies partial action by calculating statistics only for recent chronological data within a predetermined time span rather than analyzing all historical data. This selective statistical analysis maintains sufficient detection accuracy for current flying height conditions while significantly reducing processing time and enabling faster response to head-disk interval variations
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 method allows for rapid and precise adjustment of head flying height, reducing the risk of contact and extending the device's lifespan by quickly detecting and responding to fluctuations in the head-disk interval.
Implementation Method 1
a heater provided near each of the heads... adjusting the head flying height
Data Source
AI summary
According to an embodiment, the method for adjusting a head flying height in a magnetic disk device including a disk, a head that writes or reads data along tracks of the disk, and a heater provided near the head includes: determining a threshold of the head flying height; calculating a statistic from the chronological data of the head flying height; and adjusting the head flying height if the statistic exceeds the threshold.