Write Bubble Modulation for Adjacent Track Interference in Magnetic Recording
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Solution Overview
Problem
In magnetic data recording systems, the mass of components like the slider and actuator causes delays in correcting the position of the write head, leading to potential data loss due to adjacent track interference when the head becomes offset from the desired data track.
Innovation Solution
A method is implemented to generate a position error signal and modulate the size of the write bubble based on this signal, allowing for instantaneous correction of the write head's position without moving physical components, thereby preventing data loss by reducing the write bubble's size when it encroaches on adjacent tracks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the slider and actuator components have mass for structural stability, then the system maintains mechanical strength and reliability, but the position correction of the write head becomes delayed when offset from the desired data track
Solution Approach 1:
The patent replaces the mechanical position correction system (actuator moving the slider) with a magnetic field-based solution. By modulating the write head bubble size dynamically, the system achieves instantaneous position correction without physical movement, eliminating the time delay inherent in mechanical systems while maintaining structural stability.
Solution Approach 2:
The patent changes the parameter of bubble size dynamically in response to head position offset. When the head is offset from the desired track, the bubble size is reduced to prevent adjacent track interference, and when centered, the bubble size is increased for normal writing operations. This parameter modulation enables instantaneous adaptation without mechanical movement.
2Ease of operation
If the write head maintains a fixed bubble size for simple control, then the system operation is straightforward, but adjacent track interference occurs when the head is offset from the desired data track
Solution Approach 1:
The patent transitions from a static bubble size to a dynamic bubble size that adapts to the head's position relative to the desired track. The bubble diameter is modulated in real-time based on position error signals, allowing the system to maintain simple control architecture while dynamically preventing adjacent track interference through size adjustment.
Solution Approach 2:
The patent applies preliminary anti-action by reducing the bubble size before actual writing occurs when the head is detected to be offset from the desired track. This preventive measure stops adjacent track interference before it can happen, rather than correcting it after the fact.
3Reliability
If the bubble size is reduced to prevent adjacent track interference, then data integrity is improved, but the writing capability on the intended track is reduced
Solution Approach 1:
The patent employs periodic modulation of the bubble size based on the head's position relative to the desired track. The bubble size is dynamically adjusted in a periodic manner - reduced when offset to prevent interference, and restored when centered to enable normal writing. This periodic action maintains both data integrity and writing capability across different operational states.
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 enables virtually instantaneous prevention of data loss by adjusting the write bubble's size without physical movement, ensuring accurate writing only on the intended track until the head is correctly aligned, thus enhancing data integrity and recording efficiency.
Implementation Method 1
An electrically conductive write coil induces a magnetic flux through the write coil. This results in a magnetic write field being emitted toward the adjacent magnetic medium
Implementation Method 2
A magnetoresistive sensor such as a GMR or TMR sensor can be employed for sensing magnetic fields from the rotating magnetic disk
Implementation Method 3
When the disk rotates, air adjacent to the disk moves along with the surface of the disk. The slider flies over the surface of the disk on a cushion of this moving air
Data Source
AI summary
A magnetic data recording system wherein the wherein adjacent track interference during writing is avoided by modulating the size of a write bubble on the magnetic media in response to a position error signal. If the position error signal indicates that the magnetic head is off-track, circuitry within the magnetic data recording system adjusts the size of the write bubble temporarily to prevent the write bubble from encroaching on a neighboring data track. This adjustment of the write bubble can be accomplished by adjusting power to the write head. Adjustment of the write bubble can also be achieved by adjusting power to a magnetic oscillator in a microwave assisted magnetic recording system (MAMR) or adjusting power to a heating element in a thermally assisted magnetic recording system.