Perpendicular Magnetic Head Return Path Design
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Solution Overview
Problem
Magnetic heads for perpendicular magnetic recording face challenges in producing a sufficient write magnetic field while reducing the length of the magnetic path through the return path section, leading to potential magnetic flux leakage and adjacent track erasure due to skew issues.
Innovation Solution
The magnetic head design includes a coil with a first and second portion, a write shield, and return path sections made of magnetic materials, with a gap part of nonmagnetic material between the main pole and the write shield, optimizing the positioning and configuration to minimize magnetic flux direction changes and prevent leakage, ensuring a sufficient write magnetic field is maintained.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the length of the magnetic path through the return path section is reduced, then the write magnetic field strength is improved, but magnetic flux leakage increases causing adjacent track erasure
Solution Approach 1:
A nonmagnetic material layer is introduced as an intermediary between the main pole and the return path section. This intermediary layer controls and directs magnetic flux, preventing leakage while maintaining a short magnetic path length. The nonmagnetic material acts as a flux barrier that channels magnetic lines through the return path section efficiently without causing adjacent track erasure.
Solution Approach 2:
The magnetic head structure employs different material properties in different regions: the main pole uses magnetic material for flux generation, the nonmagnetic material layer provides flux direction control, and the return path section uses magnetic material for flux return. This local differentiation of material quality optimizes both write field strength and flux containment.
2Productivity
If the track width is reduced to achieve higher recording density, then the write head section size is reduced, but the skew-induced adjacent track erasure becomes more severe
Solution Approach 1:
The nonmagnetic material layer serves as a mediator that confines magnetic flux to the intended track area. By controlling flux direction and preventing lateral spread, this intermediary layer enables tighter track widths without the skew-induced erasure that would otherwise occur in narrower tracks.
Solution Approach 2:
The invention changes the magnetic path parameters by introducing the nonmagnetic material layer, which alters flux distribution and direction. This parameter change allows the system to operate at higher recording densities with reduced track widths while maintaining write integrity through improved flux containment.
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 configuration allows the main pole to produce a write magnetic field of sufficient magnitude while reducing the length of the magnetic path, effectively preventing adjacent track erasure and enhancing recording density.
Implementation Method 1
a coil that produces a magnetic field corresponding to data to be written on a recording medium
Implementation Method 2
a main pole that allows a magnetic flux corresponding to the magnetic field produced by the coil to pass, and produces a write magnetic field for writing the data on the recording medium
Implementation Method 3
The write shield and the one or more return path sections have the function of capturing a magnetic flux that is produced from the end face of the main pole and spreads in directions other than the direction perpendicular to the plane of a recording medium
Data Source
AI summary
A magnetic head includes a coil, a main pole, a write shield, and a return path section. The return path section is located forward of the main pole in a direction of travel of a recording medium to thereby define a space. The coil includes a first coil element and second coil elements extending to pass through the space. The second coil elements are located forward of the first coil element in the direction of travel of the recording medium. The return path section includes a first portion located such that the first coil element is interposed between the first portion and the medium facing surface, and a second portion located such that the second coil elements are interposed between the second portion and the medium facing surface.