Perpendicular Magnetic Recording Head Side Shield Positioning
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In perpendicular magnetic recording systems, a high skew angle of the main pole relative to the track direction leads to side erase, where the side edge of the main pole inadvertently erases signals in adjacent tracks, and increasing guard band width to prevent this reduces track density, while existing side shields degrade the recording ability of the main pole.
Innovation Solution
A perpendicular magnetic recording head with a main pole and a side shield magnetically spaced in the cross-track direction, where the trailing edge of the side shield is positioned on the leading side of the main pole, and a return pole forms a closed magnetic circuit to reduce side erase without degrading the recording ability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the perpendicular write head is located over the inner or outer periphery of the magnetic disk, then the skew angle increases, but side erase occurs at the side edge of the main pole
Solution Approach 1:
A side shield is introduced as an intermediary component between the main pole and the adjacent track. The side shield is positioned at a predetermined distance from the main pole and extends along the trailing edge, intercepting and redirecting the magnetic flux that would otherwise cause side erase. This mediator structure allows the write head to operate at high skew angles without erasing adjacent tracks.
Solution Approach 2:
The harmful side erase effect is extracted and isolated by positioning the side shield at a specific distance from the main pole. The side shield captures the straying magnetic flux at its source and redirects it, effectively separating the main recording function from the harmful side erase effect. This extraction allows the main pole to focus on recording while the side shield handles the flux redirection.
2Reliability
If the guard band width between recording tracks is increased to avoid side erase, then side erase is prevented, but track density decreases
Solution Approach 1:
The side shield acts as a mediator that enables tighter track spacing by intercepting and redirecting magnetic flux before it can erode adjacent tracks. This allows guard bands to be minimized or eliminated while maintaining signal integrity, thereby increasing track density without sacrificing reliability.
Solution Approach 2:
The invention changes the magnetic flux distribution parameters by introducing the side shield at a optimized distance from the main pole. This parameter change in flux confinement allows tracks to be placed closer together while maintaining the same level of signal integrity protection that would otherwise require larger guard bands.
3Object-generated harmful factors
If a side shield is added to reduce side erase, then side erase is reduced, but recording ability of the main pole degrades
Solution Approach 1:
The side shield is designed with local quality optimization - it is positioned at a specific distance from the main pole and has a specific width and position along the trailing edge. This localized configuration ensures that the side shield only intercepts flux that would cause side erase, while leaving the central flux path to the main pole intact, thereby maintaining recording ability while reducing side erase.
Solution Approach 2:
The side shield performs a partial function - it only needs to intercept and redirect the portion of magnetic flux that strays toward adjacent tracks, rather than controlling all flux. This partial action is sufficient to reduce side erase while minimizing interference with the main pole's recording capability.
4Object-generated harmful factors
If the side shield is positioned closer to the main pole, then side erase is reduced more effectively, but recording ability degrades further
Solution Approach 1:
The invention optimizes the distance parameter between the side shield and main pole to achieve the best balance. By carefully selecting this parameter, the side shield can be positioned close enough to effectively reduce side erase, yet far enough to avoid degrading the recording ability and signal quality of the main pole.
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 inhibits side erase at the main pole's side edge, maintaining recording ability and enhancing track density by optimizing the SSW/PL ratio and bevel angle, thereby improving recording density without degrading signal quality.
Implementation Method 1
a side shield magnetically spaced from a main pole in a cross-track direction
Implementation Method 2
a return pole provided at a trailing side of the main pole to form a closed magnetic circuit
Data Source
AI summary
According to one embodiment, a perpendicular magnetic recording head includes a main pole which generates a recording magnetic field, a return pole which forms a closed magnetic circuit for the recording magnetic field, and a side shield magnetically spaced from the main pole in a cross-track direction in which a point on a trailing edge of the side shield which is closest to the main pole is positioned on a leading side of a trailing edge of the main pole.