Magnetic Head Return Path Inclined Surface Design
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Solution Overview
Problem
Magnetic heads for perpendicular magnetic recording systems face issues with adjacent track erasure due to skew, leading to degradation in recording density and write characteristics, particularly caused by the configuration of return path sections and heat-induced expansion.
Innovation Solution
A magnetic head design featuring a first return path section with an inclined surface and a gap part between the main pole and the return path section, along with a nonmagnetic layer to suppress heat-induced changes, reduces exposure area and prevents magnetic field leakage, thereby preventing adjacent track erasure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a return path section is provided in a magnetic head for perpendicular magnetic recording, then adjacent track erasure is prevented and recording density is improved, but the return path section exposes a large area in the medium facing surface which causes magnetic field leakage and degrades write characteristics
Solution Approach 1:
The return path section is configured with an inclined surface instead of a vertical or flat surface. The inclined surface reduces the exposure area in the medium facing surface while maintaining the magnetic flux return path function. This curved/angled geometry minimizes the area from which magnetic field leakage can occur.
Solution Approach 2:
The return path section is positioned at a specific location farther from the substrate than the main pole, and only the necessary portion is exposed. The inclined surface design locally modifies the exposure characteristics to reduce magnetic field leakage in critical areas while maintaining functionality.
2Stability of the object's composition
If the return path section is located farther from the substrate than the main pole, then magnetic flux return path is improved, but heat-induced expansion affects the exposed area and causes adjacent track erasure
Solution Approach 1:
The inclined surface of the return path section reduces the exposure area compared to a vertical configuration. This reduced exposure area is less susceptible to heat-induced expansion effects, preventing the expansion from causing adjacent track erasure while maintaining the magnetic flux return path.
Solution Approach 2:
The inclined surface design preemptively reduces the exposure area to counteract the potential harmful effects of heat-induced expansion before it occurs. By minimizing the exposed area, the design prevents expansion-related adjacent track erasure.
3Reliability
If shields are added near the main pole to prevent adjacent track erasure, then recording density is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The return path section serves dual functions: it provides the magnetic flux return path and simultaneously acts as a shield to prevent adjacent track erasure. By integrating these two functions into a single structure, the design avoids adding separate shield components, thus reducing device complexity.
Solution Approach 2:
The return path section is merged with the shielding function. Instead of having separate return path and shield structures, the return path section is designed to perform both magnetic flux return and adjacent track protection, simplifying the overall head structure.
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 prevents adjacent track erasure and enhances recording density by reducing magnetic field leakage and heat-induced degradation, improving write and read characteristics.
Implementation Method 1
a coil, a main pole, a first return path section made of a magnetic material... The coil produces a magnetic field corresponding to data to be written on the recording medium. The main pole 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 2
The first return path section is magnetically connected to part of the main pole away from the medium facing surface... having the function of capturing a magnetic flux that is produced from the end face of the main pole and spreading in directions other than the direction perpendicular to the plane of the recording medium, so as to prevent the magnetic flux from reaching the recording medium. The one or more return path sections also have the function of allowing a magnetic flux that has been produced from the end face of the main pole and has magnetized the recording medium to flow back to the main pole
Data Source
AI summary
A magnetic head includes a main pole and a return path section located above a top surface of a substrate. The main pole has an end face located in a medium facing surface. The return path section is located on the front side in the direction of travel of a recording medium relative to the main pole and is farther from the top surface of the substrate than is the main pole. The return path section has: a front end face located on the front side of the main pole in the medium facing surface; and an inclined surface located on the front side and connected to the front end face. The inclined surface is not exposed in the medium facing surface. An angle greater than 90° is formed between the front end face and the inclined surface.