Microactuator Fly Height Instability Detection During Load
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Solution Overview
Problem
Data storage devices face fly height instability issues during load operations due to manufacturing defects and transient conditions, which can lead to head-disk contact and damage, and existing technologies lack effective detection and corrective measures.
Innovation Solution
Incorporating a microactuator configured as a sensor to detect fly height instability through monitoring sensor signals, with control circuitry processing these signals to identify and correct instability by adjusting the load operation trajectory or disabling faulty heads, using wire-ORed and time-division multiplexed sensor signal evaluations, and verifying with additional signals like VCM current and spindle speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the head is launched from the ramp over the spinning disk surface during load operation, then the data storage device can access data tracks, but fly height instability occurs due to manufacturing defects and transient conditions
Solution Approach 1:
The system performs preliminary detection of fly height instability during the load operation by monitoring microactuator sensor signals before head-disk contact occurs. This allows the system to identify unstable heads proactively and take corrective action (modifying load trajectory or depopulating the head) to prevent damage, thus maintaining reliability while preserving productivity
Solution Approach 2:
The system uses feedback from microactuator sensor signals to continuously monitor head fly height during load operations. The control circuitry processes these signals to detect instability conditions and automatically adjusts the load operation trajectory or disables faulty heads, creating a closed-loop control system that resolves the contradiction between maintaining productive load operations and ensuring fly height stability
2Reliability
If microactuator sensor signals are monitored during load operation to detect fly height instability, then head-disk contact can be prevented, but device complexity increases due to additional sensing and control circuitry
Solution Approach 1:
The microactuator is configured to serve dual functions: it acts as both an actuator for head positioning and as a sensor for fly height detection. By utilizing the existing microactuator structure for sensing purposes, the system avoids adding separate dedicated sensor components, thereby reducing the increase in device complexity while still achieving reliable head-disk contact prevention
Solution Approach 2:
The microactuator serves itself by generating sensor signals that provide feedback about its own performance and the head's fly height condition. This self-service capability eliminates the need for external sensing mechanisms, reducing system complexity while maintaining the ability to detect and prevent fly height instability
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
Effectively detects and mitigates fly height instability, preventing head-disk contact and ensuring stable operations by modifying load trajectories or depopulating faulty heads, thereby enhancing data storage device reliability and longevity.
Implementation Method 1
a first microactuator configured to actuate a first head over a first disk surface... wherein the first microactuator is configured into a first sensor... and a first load operation is executed to load the first head over the first disk surface
Data Source
AI summary
A data storage device is disclosed comprising a first disk surface, a first head, and a first microactuator configured to actuate the first head over the first disk surface. The first microactuator is configured into a first sensor, and a first load operation is executed to load the first head over the first disk surface. A fly height instability of the first head is detected during the first load operation based on a first sensor signal generated by the first microactuator.