Magnetic Head With Nonmagnetic Gap For Perpendicular Recording
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Solution Overview
Problem
Magnetic heads for perpendicular magnetic recording face challenges in preventing undesirable protrusion of the medium facing surface due to heat-generated expansion of magnetic layers and in reducing the magnetic path length of return path sections, which affects recording density and write characteristics.
Innovation Solution
The magnetic head design includes a write shield with a gap part made of nonmagnetic material between the main pole and the write shield, and return path sections made of magnetic material, with a yoke part and coupling layers to manage magnetic flux and prevent protrusion, allowing for efficient use of space and reduced magnetic path lengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the magnetic path length of return path sections is reduced to enhance recording density, then recording density is improved, but heat-generated expansion of magnetic layers causes undesirable protrusion of the medium facing surface
Solution Approach 1:
A nonmagnetic gap part is introduced as an intermediary element between the main pole and write shield. This gap part serves as a mediator that prevents magnetic flux leakage while isolating the magnetic layers from direct contact, thereby preventing heat-generated protrusion while maintaining reduced magnetic path length for high recording density
Solution Approach 2:
The return path section is segmented into distinct functional parts: magnetic material sections for flux conduction and a nonmagnetic gap part for isolation. This segmentation allows the magnetic path to be shortened for high density while the gap part prevents thermal expansion-induced protrusion by electrically and magnetically isolating the layers
2Ease of operation
If coil elements are positioned closer to the medium facing surface to improve write characteristics, then write characteristics are improved, but heat from coil elements causes expansion and protrusion of magnetic layers
Solution Approach 1:
The nonmagnetic gap part acts as a thermal intermediary that separates the coil elements from the magnetic layers. This allows the coil to be positioned close to the medium facing surface for improved write characteristics while the gap part provides thermal isolation, preventing heat-induced expansion and protrusion of the magnetic layers
3Manufacturing precision
If the track width of the write head unit is reduced to achieve higher recording density, then recording density is improved, but adjacent track erase increases due to skew
Solution Approach 1:
The harmful magnetic flux that would cause adjacent track erase is extracted and redirected through the write shield and return path section configuration. The write shield captures straying flux, and the return path section with gap part guides it back, preventing it from erasing adjacent tracks while allowing the track width to be reduced for high density
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 effectively prevents undesirable protrusion of the medium facing surface and reduces the magnetic path length, enhancing recording density and write characteristics by efficiently managing magnetic flux and heat distribution.
Implementation Method 1
a coil that produces a magnetic field corresponding to data to be written on the recording medium
Implementation Method 2
return path sections made of magnetic material, with a yoke part and coupling layers to manage magnetic flux
Implementation Method 3
gap part made of nonmagnetic material between the main pole and the write shield
Data Source
AI summary
A magnetic head includes a coil, a main pole, a gap part, a write shield, and a return path section. The return path section includes a yoke part with a first coupling layer connected to the write shield and a second coupling layer magnetically coupling the first coupling layer to the yoke part. The second coupling layer has an end face facing toward a medium facing surface and located away from the medium facing surface. The coil includes i) a first coil element disposed with the first coupling layer interposed between the medium facing surface and the first coil element and ii) a plurality of second coil elements aligned perpendicularly to the medium facing surface and disposed with the second coupling layer interposed between the medium facing surface and the second coil elements. The first coil element being interposed between the main pole and the second coil elements.