Multitrack Servo Marks with Perpendicular and Longitudinal Fields
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Solution Overview
Problem
Current magnetic recording technologies are constrained by a one-dimensional system design, limiting areal density and drive performance due to the inability to effectively utilize the two-dimensional nature of magnetic recording media, particularly in sensing both perpendicular and longitudinal magnetic fields.
Innovation Solution
Implementing a multitrack servo system with readers that span multiple user data tracks to detect both perpendicular and longitudinal magnetic fields, allowing for improved position error detection, track-to-track phase error correction, and Gray code error correction using a combination of signals from multiple readers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a one-dimensional system design is used for magnetic recording, then the system complexity is reduced, but the areal density and drive performance are limited
Solution Approach 1:
The patent transitions from a one-dimensional sensing system to a two-dimensional sensing system by implementing readers that can detect both perpendicular and longitudinal magnetic field components. This dimensional expansion allows the system to utilize the full two-dimensional nature of magnetic recording media, thereby increasing areal density without proportionally increasing system complexity
2Measurement precision
If readers span multiple user data tracks to detect both perpendicular and longitudinal fields, then position error detection accuracy is improved, but the device complexity increases
Solution Approach 1:
The patent implements multi-functional readers that simultaneously perform multiple sensing functions: detecting perpendicular magnetic fields, detecting longitudinal magnetic fields, and generating position error signals. By consolidating these functions into unified readers that span multiple tracks, the system achieves high measurement precision without proportionally increasing device complexity
Solution Approach 2:
The patent uses the longitudinal magnetic field as an intermediary to enable more accurate position error detection. The longitudinal field sensing acts as a mediator that provides additional information about head position and orientation, allowing for improved precision without requiring separate dedicated sensing systems
3Loss of time
If multitrack servo sectors with crosstrack width spanning multiple user data tracks are used, then servo writing time is reduced, but the difficulty of detecting and measuring increases
Solution Approach 1:
The patent segments the servo sector into distinct functional regions including preamble fields, track ID fields, and burst fields, each with specific magnetic field patterns. This segmentation allows for efficient encoding that reduces servo writing time while providing structured patterns that facilitate accurate detection and measurement through the multitrack readers
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 enhances data storage efficiency, reduces servo writing time, and improves robustness by enabling the detection of errors and phase shifts, leading to increased areal density and better drive performance.
Implementation Method 1
The first reader provides a first signal based on detecting a total longitudinal field of the servo sector
Implementation Method 2
The second reader provides a second signal based on detecting a total perpendicular field of the servo sector
Data Source
AI summary
A servo sector on a disk is read via first and second readers that both span two or more user data tracks. The servo sector has a crosstrack width that spans the two or more user data tracks. The first reader provides a first signal based on detecting a total longitudinal field of the servo sector. The second reader provides a second signal based on detecting a total perpendicular field of the servo sector. A position error of the first and second readers is detected using. A value of the first signal can be used to detect a position error, detect a track-to-track phase error, and/or detect a Gray code error of a track ID field of the servo sector.