Perpendicular Magnetic Recording Head Trailing Shield Design
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Solution Overview
Problem
In perpendicular magnetic recording systems, the generation of a magnetic field with reverse polarity can cause deterioration and deletion of existing recorded data, while attempts to enhance the magnetic field gradient lead to increased magnetic flux affecting adjacent tracks, necessitating a solution that maintains gradient steepness without generating reverse polarity fields.
Innovation Solution
A perpendicular magnetic recording head design featuring a main magnetic pole, an auxiliary magnetic pole, a trailing shield with a non-magnetic film, and side shields, where the trailing shield has a thinner film thickness on its trailing side, effectively suppressing the generation of magnetic fields with reverse polarity without deteriorating the magnetic field gradient.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the distance between the main pole and the medium is reduced to enhance magnetic field gradient, then the recording resolution and S/N ratio are improved, but the risk of contact between the main pole and the medium increases
Solution Approach 1:
A shield is introduced as an intermediary component between the main magnetic pole and the magnetic medium. This shield absorbs magnetic flux from adjacent tracks and prevents direct contact between the main pole and medium, thereby maintaining a steep magnetic field gradient for high-resolution recording while eliminating the contact risk through physical separation.
2Measurement precision
If shields are added to absorb magnetic flux and make the magnetic field gradient steeper, then the recording characteristics are improved, but magnetic flux may still affect adjacent tracks
Solution Approach 1:
A shield structure is positioned between the main magnetic pole and adjacent tracks to absorb stray magnetic flux. This intermediary component prevents magnetic flux from leaking into adjacent tracks while allowing the main pole to generate a steep magnetic field gradient for improved recording characteristics.
Solution Approach 2:
The shield is strategically positioned only in specific regions where magnetic flux leakage to adjacent tracks occurs. By applying the shielding function locally rather than uniformly, the design maintains steep magnetic field gradient where needed for recording while absorbing flux only in the directions that would affect adjacent tracks.
3Device complexity
If conventional longitudinal magnetic recording is used, then the system is simpler, but thermal fluctuation in magnetization prevents further increase in recording density
Solution Approach 1:
The patent transitions from longitudinal magnetic recording to perpendicular magnetic recording, representing a fundamental change in the orientation phase of magnetization. This phase transition enables higher recording densities by recording magnetization perpendicular to the disk surface, where thermal fluctuation effects are minimized and stability is improved.
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 prevents the deterioration or deletion of recorded data by controlling magnetic flux and maintaining a steep magnetic field gradient, enabling high-density and reliable magnetic recording.
Implementation Method 1
a trailing shield disposed on the trailing side of the main magnetic pole with a non-magnetic film placed in-between
Implementation Method 2
magnetizing signal is recorded with a magnetic monopole head in the perpendicular direction
Data Source
AI summary
Embodiments of the invention reduce generation of a magnetic field with a polarity reverse to that of the recording magnetic field, without deteriorating a gradient in the magnetic field. An embodiment of a magnetic disk device according to the present invention suppresses deviation and erase of already recorded data. In an embodiment, the perpendicular magnetic recording head includes the main magnetic pole, an auxiliary magnetic pole, a trailing shield disposed on the trailing side of the main magnetic pole with a non-magnetic film placed in-between, and side shields disposed on both the sides of the main magnetic pole in the direction of the track width with a non-magnetic film placed in-between. The trailing shield has on the trailing side a portion where film thickness is thinner on the trailing side than the thickness of its element in the height direction in its position facing the main magnetic pole. Adoption of this configuration allows suppression of generation of the magnetic field having a polarity reverse to that of the recording magnetic field, without deteriorating the magnetic field gradient. Also in the portion where the side shields face the main magnetic pole, the side shields have the portion where the film is thinned down in thickness.