Asymmetric Shield Magnetic Head for Perpendicular Recording
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Solution Overview
Problem
Magnetic heads for perpendicular magnetic recording face challenges in suppressing wide-range adjacent track erase and reducing heat-induced protrusion, while maintaining precise bit pattern location and improving linear recording density.
Innovation Solution
A magnetic head design featuring a pole layer with adjacent end faces of the pole layer and shield separated by a gap layer, where the shield has portions forward and backward of the pole layer, allowing magnetic flux to be effectively managed to prevent unwanted magnetization and reduce heat-induced issues, with coils generating fields that pass through the pole layer and shield to enhance write characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the track width is reduced to achieve higher recording density, then linear recording density is improved, but write characteristics such as overwrite property suffer degradation
Solution Approach 1:
The patent applies local quality by creating an asymmetric shield structure where the backward extension length differs from the forward extension length. Specifically, the shield extends backward from the pole layer end face by a longer distance than it extends forward, creating different magnetic field control characteristics in different directions. This localized structural variation optimizes the magnetic field distribution at the track edges, improving overwrite capability while maintaining reduced track width for high recording density.
2Reliability
If a conventional shield structure is used, then adjacent track erase is suppressed, but wide-range adjacent track erase occurs due to skew
Solution Approach 1:
The patent applies asymmetry by designing the shield with unequal extension lengths in forward and backward directions from the pole layer end face. The backward extension length is specifically made longer than the forward extension length. This asymmetric configuration compensates for the skew effect in perpendicular magnetic recording, preventing wide-range adjacent track erase while maintaining precise bit pattern location even when the magnetic head position varies across tracks.
3Manufacturing precision
If the pole layer and shield are placed close together, then magnetic flux management is improved, but heat-induced protrusion increases
Solution Approach 1:
The patent applies segmentation by dividing the shield into two distinct portions: a forward extension portion and a backward extension portion, with the gap layer positioned between the pole layer and the shield. This segmented structure allows independent optimization of magnetic flux management (through close positioning) and thermal management (through the gap layer spacing), enabling the shield to be positioned close to the pole layer for flux efficiency while the gap layer mitigates heat-induced protrusion.
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 design effectively suppresses wide-range adjacent track erase, reduces heat-induced protrusion, and improves the precision of bit pattern location, thereby enhancing linear recording density and write characteristics.
Implementation Method 1
a first coil and a second coil which each generate a magnetic field corresponding to data to be written on the recording medium
Implementation Method 2
a pole layer having an end face located in the medium facing surface, allowing a magnetic flux corresponding to the field generated by each of the first and second coils to pass therethrough, and generating a write magnetic field
Implementation Method 3
the shield has a function of returning a magnetic flux that has been generated from the end face of the pole layer and has magnetized the recording medium
Data Source
AI summary
A magnetic head comprises a pole layer, a first coil, a second coil, and a shield. The shield incorporates: a first portion located backward of the pole layer along the direction of travel of a recording medium; a second portion located forward of the pole layer along the direction of travel of the recording medium; and two coupling portions. The first portion has an end face located in a medium facing surface. The two coupling portions couple the first and second portions to each other without touching the pole layer. Part of the first coil passes through a space surrounded by the pole layer and the first portion. Part of the second coil passes through a space surrounded by the pole layer and the second portion.