Thin-Film Magnetic Head Shield Layer Overlap Control
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Solution Overview
Problem
Conventional thin-film magnetic heads for perpendicular recording are susceptible to unintended writing due to external magnetic fields, leading to degradation of recorded signals, especially from sources like music players and cellular phones, as they lack effective shielding against external magnetic interference.
Innovation Solution
A magnetic recording/reproducing system with a thin-film magnetic head featuring a write shield layer and read shield layers positioned to prevent overlap until a maximum skew angle, ensuring that external magnetic fields do not cause signal degradation by focusing magnetic fields away from sensitive areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a write shield layer is added to reduce magnetic flux spread and enhance recording density, then recording density is improved, but the device becomes more susceptible to external magnetic fields causing unintended writing
Solution Approach 1:
A nonmagnetic layer is introduced as an intermediary between the write shield layer and external magnetic field sources. This nonmagnetic layer acts as a mediator that blocks external magnetic fields from reaching the write shield layer, thereby preventing unintended writing while preserving the write shield layer's function of concentrating magnetic flux for high-density recording.
Solution Approach 2:
The magnetic head structure is segmented into distinct functional layers: the write shield layer for flux concentration, the nonmagnetic layer for external field blocking, and the main magnetic pole layer for signal generation. This segmentation allows each layer to perform its specific function independently, resolving the contradiction between flux concentration and external field susceptibility.
2Manufacturing precision
If the write shield layer is positioned closer to the air bearing surface to improve flux concentration, then recording density increases, but the risk of external magnetic field interference increases
Solution Approach 1:
The nonmagnetic layer serves as a protective intermediary positioned between the write shield layer and external magnetic field sources. This allows the write shield layer to be optimally positioned for flux concentration without direct exposure to external magnetic fields, thereby maintaining both high recording density and data integrity.
Solution Approach 2:
The nonmagnetic layer is placed in advance as a protective barrier against external magnetic fields. This prior cushioning prevents harmful magnetic fields from reaching the sensitive write shield layer before interference can occur, ensuring reliable operation in environments with external magnetic sources.
3Device complexity
If conventional magnetic head structures are used without additional shielding layers, then device complexity is reduced, but unintended writing occurs due to external magnetic fields
Solution Approach 1:
A nonmagnetic layer is introduced as a simple intermediary element that effectively blocks external magnetic fields. This addition provides protection against unintended writing while maintaining relatively simple device complexity, as the nonmagnetic layer can be integrated into the existing magnetic head structure without requiring complex mechanical or electrical systems.
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 system effectively shields recorded signals from external magnetic interference, maintaining data integrity even under strong external magnetic fields, with track erasure rates exceeding 80% in non-overlapping configurations, compared to 50% when overlaps occur.
Implementation Method 1
a thin-film coil adapted to generate a magnetic flux, a magnetic pole layer that extends rearward from its surface opposite to said recording medium to generate a magnetic field on the basis of the magnetic flux generated at said thin-film coil
Implementation Method 2
a write shield layer for reducing the spread of a magnetic flux released off a main magnetic pole layer is used in combination with the main magnetic pole layer that extends in the direction orthogonal to the air bearing surface
Implementation Method 3
a magneto-resistive effect device, and an upper read shield layer and a lower read shield layer located below said upper read shield layer so as to magnetically shield off said device
Data Source
AI summary
The invention provides a magnetic recording/reproducing system constructed such that until the skew angle is past the maximum skew angle αmax, the edges of the write shield layer and the edges of the lower read shield layer do not overlap on the same track, so that upon application of an external magnetic field, the already written signals are kept back from degradation.