Magnetic Storage Reader Bridge Aligning Shield Moments
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Solution Overview
Problem
The magnetic recording head in hard disk drives faces instability and reduced signal-to-noise ratio due to canting of side shields' magnetic moments, which affects the read signal and resolution of stored data bits.
Innovation Solution
A shielding structure with a bridge is introduced above the sensor stack, aligning the magnetic moments of side shields and maintaining a stable baseline bias, thereby reducing field canting and enhancing signal resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If side shields are used to isolate the magnetic sensor from magnetic flux from adjacent data bits, then signal resolution is improved, but magnetic moment canting in the side shields produces instability and reduces signal-to-noise ratio
Solution Approach 1:
A bridge structure is introduced as an intermediary element between the side shields and the sensor stack. This bridge aligns the magnetic moments of the side shields, preventing canting-induced instability while preserving the shielding effect. The bridge acts as a mediator that transmits and organizes magnetic flux, ensuring stable magnetic moment orientation in the side shields without compromising their isolating function.
Solution Approach 2:
The bridge structure modifies the magnetic flux distribution parameters by providing a preferred path for magnetic flux. This changes the magnetic moment orientation parameters of the side shields from canted/unstable states to aligned/stable states parallel to the disk surface, thereby improving signal stability while maintaining the shielding geometry that provides resolution.
2Stability of the object's composition
If side shields maintain oriented internal magnetic moment to provide baseline bias, then sensor stability is improved, but field canting occurs which affects read signal quality
Solution Approach 1:
The bridge serves as an intermediary that couples the side shields magnetically, enabling them to maintain stable oriented magnetic moments while preventing canting. The bridge transmits magnetic flux in a controlled manner, ensuring that the side shields' magnetic moments remain aligned parallel to the disk surface, thus providing stable baseline bias without degrading read signal quality.
3Reliability
If bridge structure is added to align magnetic moments of side shields, then signal-to-noise ratio is improved, but device complexity increases
Solution Approach 1:
The shielding structure is segmented into distinct functional components: side shields for isolation, a bridge for alignment, and a sensor stack for detection. This segmentation allows each component to be optimized independently - the side shields maintain their shielding geometry while the bridge provides the necessary magnetic moment alignment function, achieving improved signal-to-noise ratio through modular design.
Solution Approach 2:
The bridge structure performs multiple functions simultaneously: it aligns the magnetic moments of the side shields, provides a magnetic flux path, and stabilizes the baseline bias. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity while achieving improved signal-to-noise ratio.
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 proposed solution stabilizes the magnetic sensor stack, improving the signal-to-noise ratio and resolution of read signals from stored data bits by aligning the magnetic flux and reducing metastable states in the side shields.
Implementation Method 1
The bridge serves to align the magnetic flux along each of the side shield inner edges, potentially mitigating field canting in the side shields and providing the sensor stack with a more stable baseline bias
Implementation Method 2
The reader may be magnetic sensor that operates on magnetoresistance, such as a giant magnetoresistance (GMR) junction or a tunneling magnetoresistance (TMR) junction
Data Source
AI summary
A reader of a magnetic recording head includes a sensor stack, a first side shield and a second side shield disposed on opposite sides of the sensor stack in a cross-track dimension, and a bridge. The bridge is configured to align magnetic moments of the first side shield and the second side shield. The bridge is disposed above the sensor stack relative to a media-facing surface of the magnetic recording head and proximate to the first side shield and the second side shield.