Tape Head Skew Control for Side Erasure in Magnetic Recording
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Solution Overview
Problem
Magnetic tape drives face challenges in maintaining track pitch due to significant side erasure effects, which result in residual tracks being narrower than desired, affecting data reliability and increasing the complexity of achieving higher track densities.
Innovation Solution
The solution involves rotating the tape head at a non-zero angle relative to the tape motion direction, controlling the skew angle of the writer transducer to form acute angles with the trailing edge and residual tracks, thereby reducing the width of erase bands between shingled tracks, allowing for increased track width or reduced track pitch while maintaining data reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If shingled track writing is used to increase track density, then track pitch is reduced, but side erasure effects cause residual tracks to be narrower than desired, reducing data reliability
Solution Approach 1:
The write gap is designed with asymmetric pole notching where the leading edge pole has a different geometry than the trailing edge pole. This creates an asymmetric magnetic field distribution that reduces the fringing fields extending into adjacent tracks, thereby minimizing side erasure effects while maintaining tight track pitch
Solution Approach 2:
The pole pieces are selectively notched at specific locations (leading edge and trailing edge) to modify the local magnetic field characteristics. This localized modification of the write gap geometry targets the specific problem of fringing field extension into adjacent tracks without affecting the overall write field strength
2Stability of the object's composition
If tape tension is increased for active tape dimensional stability compensation, then track dimensional stability is improved, but tape breakage risk and head friction increase
Solution Approach 1:
The patent replaces the mechanical tape tensioning system with a magnetic field-based solution. By using asymmetric pole notching to control side erasure, the system eliminates the need for high tape tension, thereby reducing mechanical stress on the tape while maintaining track dimensional stability
Solution Approach 2:
The invention changes the magnetic field parameters through pole geometry modification rather than changing mechanical parameters like tape tension. This parameter change in the magnetic field distribution achieves the desired track stability without the harmful effects of increased mechanical tension
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 approach effectively reduces the width of erase bands, enabling a 33% increase in usable track width and improving the signal-to-noise ratio by +0.5 dB, facilitating higher track densities and data reliability.
Implementation Method 1
Data is written on the magnetic recording media by moving a magnetic recording transducer to a position over the media where the data is to be stored. The magnetic recording transducer then generates a magnetic field in a write bubble
Implementation Method 2
Side erasing or erasure, is a known phenomenon caused by fringing fields that spill out beyond the edge of the write gap of a ring writer beyond the trailing edge of the write bubble that defines the written track
Implementation Method 3
the tape head is rotated at a non-zero angle relative to the first linear direction of tape motion as the second linear track of data is being written, and a trailing edge of the writer transducer of the tape head writing the second linear track of data forms an acute angle with respect to a longitudinal edge of the second linear track
Data Source
AI summary
In one aspect of the present disclosure, the degree of side erasure occurring in neighboring tracks is controlled by controlling the skew angle of the tape head, relative to the longitudinal direction of motion of the tape past the head as a track is written. In one embodiment, the tape head is rotated relative to the longitudinal direction of tape travel, and the trailing edge of the tape head which forms an acute angle with the edge of a track being written, is used for writing tracks at a desired track pitch. Other aspects and advantages may be provided, depending upon the particular application.