Magnetic Head Testing via Multi-Direction Magnetization
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Solution Overview
Problem
Conventional methods for testing the anti-high temperature performance of magnetic heads are limited in sensitivity and cannot effectively screen out defective heads without heating, especially when a heating element is not equipped, and fail to detect all defective heads using common magnetization.
Innovation Solution
Applying multiple magnetic fields with different intensities in various directions perpendicular to the air bearing surface and shielding layers to measure output parameter curves, allowing for the identification of defective magnetic heads without heating, using a method that includes applying first and second magnetic fields in specific directions and judging variations beyond allowable values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional common magnetization direction testing is used, then the testing process is simple and widely applicable, but the sensitivity for detecting anti-high temperature performance defects is insufficient
Solution Approach 1:
The testing method is segmented into three distinct magnetization directions: common magnetization direction (0° to ABS), perpendicular magnetization direction (90° to ABS), and intermediate magnetization direction (45° to ABS). Each direction targets different defect characteristics, with the perpendicular and intermediate directions specifically enhancing sensitivity to anti-high temperature performance defects that conventional methods miss.
Solution Approach 2:
The invention adds dimensional complexity by introducing multiple magnetization directions (0°, 45°, 90°) instead of relying solely on the conventional single direction. This multi-dimensional approach enables detection of defects that are invisible to conventional single-direction testing, particularly those related to thermal expansion and distortion under high temperature conditions.
2Reliability
If heating elements are equipped in magnetic heads for testing, then anti-high temperature performance can be tested under high temperature conditions, but the testing apparatus becomes more complex and not all heads have heating elements
Solution Approach 1:
The invention replaces the thermal field approach (heating elements and high temperature environments) with a magnetic field approach. By applying magnetic fields in multiple directions and analyzing output variations, the method indirectly detects thermal expansion and distortion characteristics without physically heating the magnetic head, thereby eliminating the need for heating elements and high temperature testing equipment.
Solution Approach 2:
The invention uses magnetic field response as an intermediary to detect thermal properties. Instead of directly measuring thermal expansion or distortion, the method measures the magnetic head's response to magnetization in different directions, which is affected by internal stress and structural integrity that would change under thermal conditions. This intermediary measurement approach achieves reliable anti-high temperature performance testing without direct thermal exposure.
3Measurement precision
If multiple magnetic fields in various directions are applied, then defective magnetic heads can be reliably detected without heating, but the testing process becomes more complex
Solution Approach 1:
The testing method employs periodic application of magnetic fields in three different directions (common, perpendicular, and intermediate) to the magnetic head. This periodic multi-directional magnetization allows comprehensive detection of defects by comparing output variations across different orientations, achieving high detection precision while maintaining systematic and repeatable testing procedures.
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 enables the reliable detection of defective magnetic heads with poor anti-high temperature performance at room temperature, improving testing precision and identifying heads that would otherwise go undetected by conventional methods, with a high success rate of over 75%.
Implementation Method 1
a magnetic field applying unit for repeating to apply a magnetic field with different intensities in a direction perpendicular to the shielding layers of the magnetic head
Implementation Method 2
the resistance of the MR element varies with the changes of an external magnetic field, which results in variation in the output of the MR read head
Data Source
AI summary
A method of testing anti-high temperature performance of a magnetic head comprises applying a second magnetic field with different intensities in a second direction and the changing first magnetic fields in a first direction, and measuring a plurality of second output parameter curves; and judging whether a variation that is beyond an allowable value is presented on the second output parameter curves, thereby screening out a defective magnetic head, therein the first direction is perpendicular to the air bearing surface of the magnetic head, and the second direction is perpendicular to the shielding layers of the magnetic head. The present invention can screen out defective magnetic heads that possess poor anti-high temperature performance without heating the magnetic head and with high precision.