Thin-Film Magnetic Head Flying Height Control via Thermal Expansion
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Solution Overview
Problem
Existing magnetic disk drive apparatuses face challenges in controlling the flying height of thin-film magnetic heads due to changes in ambient temperature and atmospheric pressure, which requires additional components like pressure sensors and large-scale mechanisms, increasing costs and size while compromising recording and reproducing performance.
Innovation Solution
A method to measure and adjust the flying height of thin-film magnetic heads without using new components like atmospheric pressure sensors, by temporarily contacting the magnetic disk with the read head element, using the read head outputs to measure flying height, and adjusting it with a heating element based on temperature and power control, thereby compensating for environmental changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pressure sensors and large-scale mechanisms are used to control flying height changes due to atmospheric pressure, then flying height control accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The magnetic disk drive apparatus uses its own existing components (magnetic disk, read head element, heating element) to measure and control flying height without requiring external pressure sensors or complex mechanisms. The system leverages the natural interaction between the read head and magnetic disk during normal operation to obtain flying height information, making the system self-sufficient.
Solution Approach 2:
The magnetic disk serves dual purposes: as the recording medium and as a reference surface for flying height measurement. The read head element performs both data reading and flying height sensing. The heating element serves both thermal compensation and flying height adjustment functions. This multi-functionality eliminates the need for dedicated pressure sensing components.
2Reliability
If pressure sensors are installed to monitor atmospheric pressure changes, then flying height stability is improved, but cost increases
Solution Approach 1:
The system uses its own operational parameters (read head output signals during normal reading operations) to infer flying height changes caused by atmospheric pressure, eliminating the need for separate pressure sensors. The existing read head electronics are repurposed to serve dual functions: data reading and flying height monitoring.
Solution Approach 2:
The system monitors changes in the read head output signal characteristics (such as signal amplitude or timing) that correlate with flying height variations. By detecting parameter changes in the existing read head signals rather than introducing new sensing components, the system maintains reliability without increasing cost.
3Adaptability or versatility
If rotational frequency is changed to control flying height, then flying height adaptability is improved, but recording capacity and transfer speed are compromised
Solution Approach 1:
The control functions are segmented: the rotational frequency maintains its primary function for data storage capacity, while a separate heating element handles flying height adjustment. This segmentation allows independent optimization of recording performance and flying height stability without compromising either function.
Solution Approach 2:
Instead of changing rotational frequency to adjust flying height, the system uses thermal expansion parameters of the heating element to control head position. The heating element's dimensional changes with temperature provide a precise, independent mechanism for flying height adjustment that does not affect disk rotation or data transfer rates.
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 allows for stable and precise flying height control, ensuring excellent read and write operations independently of environmental conditions, without the need for additional sensors or large mechanisms, thus reducing costs and maintaining performance.
Implementation Method 1
providing a heating element in a thin-film magnetic head, and by causing a head element end to protrude toward a magnetic disk by the heat generated from the heating element
Implementation Method 2
reads data signals by receiving a signal magnetic field from the magnetic disk by using a magnetoresistive (MR) effect element
Implementation Method 3
writes data signals by applying a signal magnetic field to the magnetic disk by using an electromagnetic coil element
Data Source
AI summary
A method of measuring a flying height of a thin-film magnetic head, capable of measuring the flying height without using a new component, such as an atmospheric pressure sensor, which is adverse to a requirement of reduction in cost and size. The method of measuring a flying height includes causing a thin-film magnetic head including a read head element receiving a signal magnetic field from a magnetic disk to contact the rotating magnetic disk temporarily; and measuring a flying height of the thin-film magnetic head by measuring outputs from the read head element at a time of the contact and during flying of the thin-film magnetic head.