Sloped Reader and Asymmetric Write Pole for Shingled Magnetic Recording
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Solution Overview
Problem
Shingled writing in magnetic recording technologies faces issues with transition curvature and skew of written tracks due to one-side squeeze and shape of the write pole, leading to signal-to-noise ratio (SNR) and bit error rate (BER) degradation.
Innovation Solution
A merged read/write structure is designed with a sloped reader and modified write pole to reduce transition curvature and skew, featuring a write pole with a trailing edge at an angle and a reader formed on a shallow slope relative to the substrate, along with asymmetrical and symmetrical write pole designs to compensate for relative skew between the reader and written tracks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional write pole design is used in shingled writing, then the write pole width can be maintained, but transition curvature and skew increase leading to SNR and BER degradation
Solution Approach 1:
The write pole is designed with an asymmetric shape where the trailing edge has different characteristics on each side. Specifically, the trailing edge includes a first corner and a second corner with different distances to the leading edge, creating an asymmetric field distribution that compensates for the one-side squeeze effect in shingled writing and reduces transition curvature
Solution Approach 2:
The write pole employs different geometric characteristics at different locations. The trailing edge has localized angular features with specific angles relative to the substrate, while the leading edge maintains a different configuration. This local differentiation allows optimization of the magnetic field distribution specifically at the track edges where squeezing occurs
2Device complexity
If the reader is formed perpendicular to the substrate, then the reader structure is simple, but relative skew between the reader and written tracks causes SNR degradation
Solution Approach 1:
The reader is formed with an asymmetric angular orientation relative to the substrate. The reader angle is specifically designed to match the transition angle of the written tracks, creating a symmetric alignment between the reader and the skewed transitions. This angular adjustment compensates for the relative skew caused by shingled writing
Solution Approach 2:
The reader formation process incorporates a change in the angular parameter from the conventional perpendicular (90 degrees) to a specific angle that matches the transition skew. This parameter adjustment optimizes the reader alignment with the written tracks while maintaining structural feasibility
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 solution effectively reduces transition curvature and skew in shingled writing, enhancing the signal-to-noise ratio (SNR) and bit error rate (BER) performance by aligning the reader with the written tracks, allowing for straighter transitions and improved writability.
Implementation Method 1
Shingled writing is a form of PMR (perpendicular magnetic recording)
Implementation Method 2
the reader may be formed at an angle with respect to a substrate to resolve the issue of relative skew between the reader and written tracks
Data Source
AI summary
A sloped reader is disclosed that reduces skew between reader and written transitions in shingled writing. The reader is formed between surfaces of S1 and S2 shields that are aligned parallel to the sloped reader. A PMR writer is described that straightens transition curvature and reduces signal-to-noise ratio in shingled writing. In one embodiment, a symmetrical writer with a bowed trailing edge where two corners have a greater pole height than a center portion may be used for either right corner or left corner shingled writing. In a second embodiment, an asymmetrical writer is formed with a straight and sloped trailing edge such that the write corner has a greater pole height than the opposite corner on the trailing edge. The bowed angle in the symmetrical writer and slope angle in the asymmetrical writer is between 5 and 45 degrees and preferably between 10 and 30 degrees.