Magnetic Head Pole Shield Configuration for Write Field
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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 connecting the write shield and the main pole, which affects recording density and write characteristics.
Innovation Solution
The magnetic head incorporates multiple coils and yoke layers made of magnetic materials, with specific configurations and orientations to allow magnetic flux to pass through the main pole effectively, including a first magnetic path on the front side and a second magnetic path on the rear side, enabling a sufficient write magnetic field despite a reduced length of the magnetic path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the magnetic path length connecting the write shield and main pole is reduced, then recording density is improved, but the write magnetic field magnitude decreases
Solution Approach 1:
The magnetic path is segmented into multiple sections with different magnetic reluctance characteristics. The write shield is connected to the main pole through a series of magnetic path sections, where each section has optimized dimensions to control magnetic flux distribution. This segmentation allows the overall magnetic path length to be reduced while maintaining sufficient write magnetic field magnitude through strategic placement of high-permeability magnetic materials in critical sections.
Solution Approach 2:
Different sections of the magnetic path are assigned different magnetic properties and dimensions. The write shield, main pole, and intermediate magnetic path sections have locally optimized characteristics such as permeability, cross-sectional area, and length. This local quality optimization ensures that magnetic flux is concentrated where needed to maintain write field strength while reducing the overall magnetic path length to improve recording density.
2Manufacturing precision
If the main pole width is reduced to achieve higher recording density, then linear recording density is improved, but overwrite capability deteriorates
Solution Approach 1:
The magnetic head structure transitions from a two-dimensional planar configuration to a three-dimensional stacked configuration. The write shield is positioned above or below the main pole in the vertical dimension, allowing magnetic flux to be concentrated in the track width direction while maintaining adequate field strength for overwriting. This dimensional change enables narrow track widths for high density while preserving overwrite capability through vertical magnetic flux concentration.
Solution Approach 2:
The magnetic head employs composite structures combining different magnetic materials with varying permeability and coercivity characteristics. The write shield and main pole are constructed from magnetic materials that optimize both field concentration for narrow tracks and field strength for overwriting. This composite material approach allows the system to achieve high linear recording density with narrow tracks while maintaining reliable overwrite capability.
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, preventing adjacent track erasure and enhancing recording density and write characteristics.
Implementation Method 1
first, second, and third coils produce magnetic fields corresponding to data to be written on a recording medium
Implementation Method 2
The main pole allows magnetic fluxes corresponding to the magnetic fields produced by the first, second, and third coils to pass, and produces a write magnetic field
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 the recording medium
Data Source
AI summary
A magnetic head includes first to third coils, a main pole, a write shield, first and second yoke layers, and first and second coupling parts. The first and second yoke layers are magnetically connected to the write shield. The first yoke layer is located on the leading side relative to the main pole, whereas the second yoke layer is located on the trailing side relative to the main pole. The first coupling part magnetically couples the main pole and the second yoke layer to each other. The second coupling part magnetically couples the first yoke layer and the second yoke layer to each other. The first coil is wound around the first coupling part, whereas the second and third coils are wound around the second coupling part.