Magnetic Tape Head Lapping Guide with Resistive Notch
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Solution Overview
Problem
Current methods for determining the target height of magnetic tape head elements lack real-time and cost-effective accuracy, leading to inefficiencies and increased scrap rates due to the reliance on resistance feedback equations with wide tolerance ranges, which are insufficient for precise machining requirements.
Innovation Solution
Incorporating a resistive transverse stripe with notches on an electrical lapping guide that measures resistance changes during material removal, allowing for precise control of the lapping process by discontinuing machining when resistance dramatically increases, indicating the target height is reached, thereby ensuring accurate machining within tight tolerance ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If resistance feedback equations are used to determine target height, then measurement can be performed, but measurement precision is insufficient due to wide tolerance ranges
Solution Approach 1:
The patent introduces an electrical lapping guide as an intermediary component between the measurement system and the tape head elements. The guide includes a resistive stripe with a notch that serves as a physical reference standard, mediating the measurement process to achieve higher precision than direct resistance feedback alone can provide.
Solution Approach 2:
The patent replaces the purely electrical resistance feedback measurement system with a hybrid system that incorporates mechanical reference features (the notch in the resistive stripe). This substitution of mechanical reference for electrical measurement enables tighter tolerance control.
2Productivity
If traditional lapping process is used, then manufacturing can proceed, but productivity is reduced due to increased scrap rates
Solution Approach 1:
The patent implements a feedback mechanism where resistance measurements are continuously monitored during the lapping process. When the resistance change indicates the lapping tool has reached the notch depth, the process automatically signals to stop, providing real-time feedback that prevents over-lapping and reduces scrap.
Solution Approach 2:
The notch is pre-formed in the resistive stripe at the exact target depth before lapping begins. This preliminary action establishes the precise stopping point in advance, eliminating the need for post-processing adjustments and reducing scrap from measurement errors.
3Stability of the object's composition
If electrical lapping guides are used on both sides, then balance control is improved, but device complexity increases
Solution Approach 1:
The patent employs asymmetric placement of electrical lapping guides on opposite sides of the tape head elements, with each guide independently positioned and measured. This asymmetric configuration enables differential measurement and control of lateral balance, detecting and correcting tilts or unevenness that symmetric arrangements would miss.
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 precise control of the lapping process, reducing scrap rates and improving the accuracy of magnetic tape head elements, allowing for narrower reader track widths and increased storage density with reduced data loss and failure rates.
Implementation Method 1
resistance is measured across the transverse stripe between the first and second leads, and a dramatic increase in resistance indicates that the material removal has reached the notch
Data Source
AI summary
An electrical lapping guide for a magnetic tape head is provided with a resistive transverse stripe with a longitudinal height affixed to a substrate. A pair of leads extend from the stripe with a notch formed therebetween. The notch has a height corresponding to a lapping target limit for associated tape head elements. During material removal of the transverse stripe and the tape head elements, resistance is measured across the stripe and a dramatic increase in resistance indicates that the material removal has reached the notch. A method for accurately machining a magnetic tape head is provided by depositing tape head elements and a resistive stripe with a notch on a substrate. Resistance is measured across leads on either side of the notch for discontinuing machining of the stripe due to a dramatic increase in resistance.