Disk Drive Fly Height Reset via Touchdown Calibration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Magnetic entropy in disk drives leads to data errors due to the degradation of magnetic grain alignment over time, exacerbated by ambient temperature and adjacent track interference, resulting in unreliable magnetic field sensing and data loss.
Innovation Solution
Implementing a fly height control system that includes a touchdown operation, fly height calibration track, and verification track to adjust and validate the fly height control signal, using techniques such as harmonic ratio estimation and error correction codes to ensure accurate head positioning and data integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If magnetic grains are written to tracks for data storage, then data capacity is improved, but magnetic entropy and adjacent track interference cause degradation over time
Solution Approach 1:
The system performs preliminary actions by implementing predictive models that anticipate magnetic entropy accumulation and adjacent track interference effects before they cause data errors. The model predicts degradation patterns based on write operations and environmental conditions, allowing proactive data protection measures to be taken.
Solution Approach 2:
The patent applies beforehand cushioning by implementing error correction codes and predictive monitoring systems that cushion against future data loss. The system prepares compensation mechanisms in advance based on predicted magnetic degradation, preventing errors before they occur rather than reacting after data corruption happens.
2Adaptability or versatility
If ambient temperature increases, then operational flexibility is improved, but magnetic entropy increases causing faster grain alignment degradation
Solution Approach 1:
The system implements feedback mechanisms that continuously monitor environmental conditions including temperature, and adjust error correction and predictive model parameters accordingly. When temperature increases are detected, the system strengthens error correction measures and adjusts predictions to account for accelerated magnetic entropy accumulation.
Solution Approach 2:
The patent applies parameter changes by dynamically adjusting error correction code strength and predictive model parameters based on environmental conditions. When temperature or other environmental factors change, the system modifies operational parameters to maintain data integrity despite varying magnetic stability conditions.
3Productivity
If write operations are performed on target tracks, then data storage capability is improved, but adjacent track interference and wide area track erasure compound over time
Solution Approach 1:
The system extracts and isolates the harmful effects of adjacent track interference and wide area track erasure by using predictive models to identify affected tracks before writing operations. The model separates the target track data from predicted interference patterns, allowing pre-correction of data that will be written to tracks susceptible to ATI and WATER effects.
4Measurement precision
If fly height control signal is adjusted for calibration, then head positioning accuracy is improved, but calibration track degradation due to magnetic entropy reduces measurement precision
Solution Approach 1:
The system applies preliminary action by implementing predictive models that forecast calibration track degradation before it significantly impacts measurement precision. The model predicts when calibration tracks will suffer from magnetic entropy effects, allowing the system to perform recalibration or adjust measurement parameters proactively rather than waiting for precision to deteriorate.
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 fly height control system effectively maintains reliable head positioning and data integrity by compensating for environmental changes and magnetic interference, reducing the impact of magnetic entropy and adjacent track interference, thereby extending the lifespan of data storage.
Implementation Method 1
a read element of the head (e.g., a magnetoresistive element) transduces the magnetic field emanating from the disk surface into a read signal
Implementation Method 2
a current is applied to a write element of the head (e.g., a write coil) to create a magnetic field which magnetizes the surface of the disk by orienting the direction of magnetic grains
Implementation Method 3
The orientation of the grains exhibits hysteresis thereby generating their own magnetic field when the write magnetic field is removed
Data Source
AI summary
A disk drive is disclosed comprising a head actuated over a disk and a fly height actuator operable to control a fly height of the head in response to a fly height control signal. A touchdown operation is executed to set an operating fly height control signal by adjusting the fly height control signal until the head contacts the disk. A fly height calibration track is then read to set a fly height reference. When calibrating the operating fly height control signal, the fly height calibration track is read and the operating fly height control signal is adjusted in response to the fly height reference. When the adjusted operating fly height control signal is invalid, the touchdown operation is re-executed to reset the operating fly height control signal and then the fly height calibration track is read to reset the fly height reference.