Low-Recess Write Pole Coil Near Shield for Hard Disk Drives
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Solution Overview
Problem
Current magnetic recording technologies face challenges in achieving high areal data density and efficient write pole dynamics due to issues like dynamic front shield saturation and reduced magnetomotive force, which affect the performance of magnetic write poles in hard disk drives.
Innovation Solution
The implementation of a low-recess coil near the media-facing surface, in conjunction with a shield wire that generates a magnetic field opposite to the write pole's field, enhances the dynamic gradient and prevents front shield saturation, while optimizing the number and placement of writer coils to balance magnetic field orientation and reduce saturation risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional write pole configurations are used, then device simplicity is maintained, but dynamic gradient enhancement and prevention of front shield saturation are insufficient
Solution Approach 1:
The write pole assembly is segmented into multiple independent coils (first write coil, second write coil, third write coil) with distinct functions. The first and second coils are positioned at different depths to provide complementary magnetic field contributions, while the third coil is specifically positioned to enhance the dynamic gradient near the media-facing surface without causing front shield saturation.
Solution Approach 2:
Each coil is assigned a specific spatial location and functional role: the first coil provides baseline write field, the second coil enhances depth penetration, and the third coil specifically targets the media-facing surface region to enhance dynamic gradient. This localized functional differentiation optimizes performance while managing complexity.
2Productivity
If more write coils are added to enhance magnetic field control, then areal data density and write pole dynamics improve, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The three write coils are positioned asymmetrically at different depths and locations relative to the write pole and shield structure. This asymmetric arrangement allows each coil to target specific spatial regions optimally, achieving enhanced areal data density and write pole dynamics without requiring a symmetric but more numerous coil array.
Solution Approach 2:
The coils are distributed across the depth dimension (recess depth) in addition to lateral positioning. By utilizing the depth dimension strategically, the invention achieves three-dimensional magnetic field control that enhances areal data density without proportionally increasing the number of coils, as each depth level contributes differently to the overall write performance.
3Force
If coil current is increased to enhance magnetic field strength, then write performance improves, but front shield saturation occurs
Solution Approach 1:
The first and second write coils are positioned to establish a preliminary magnetic field that prepares the magnetic path before the third coil enhances the dynamic gradient. This staged approach allows the system to achieve strong write fields without immediately saturating the front shield, as the field buildup occurs in controlled stages through multiple coil contributions.
Solution Approach 2:
The third write coil acts as an intermediary element that specifically enhances the dynamic gradient in the media-facing region without directly contributing to the bulk magnetic field strength. This intermediary coil provides the necessary field enhancement for high-performance writing while its localized positioning prevents direct saturation of the front shield.
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 improves areal data density and high data rate performance by enhancing the magnetic gradient and write pole dynamics, reducing the risk of front shield saturation, and allowing for efficient operation at moderate currents.
Implementation Method 1
write coils that generate a first magnetic field during a switching event
Implementation Method 2
conductive element is disposed proximate the shield and configured to generate a second magnetic field opposite to the first magnetic field during the switching event
Data Source
AI summary
An apparatus includes a write pole magnetically coupled to write coils that generate a first magnetic field during a switching event. The apparatus includes a shield at a media-facing surface and proximate the write pole. A conductive element is disposed proximate the shield and configured to generate a second magnetic field opposite to the first magnetic field during the switching event. A selected one of the write coils is located adjacent the shield separate from others of the write coils.