Disk Drive Head Ramp Detection Using Fly Height Sensor
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Solution Overview
Problem
Existing disk drive systems face issues with accurately determining the head's parked state and detecting the ramp location, leading to potential failures during host command execution and inefficient use of disk space due to malfunctions in control firmware and lack of precise ramp detection.
Innovation Solution
The implementation of a fly height actuator and control circuitry that decreases the head's fly height to detect when the head contacts the ramp by evaluating a fly height signal exceeding a threshold, utilizing temperature-sensitive sensors and calibration procedures to ensure accurate ramp detection and maximize usable disk space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If control firmware is used to maintain head state information, then head positioning control is achieved, but system reliability deteriorates due to potential firmware malfunctions
Solution Approach 1:
The system uses the fly height sensor to automatically detect head-ramp contact and generate signals that directly control the unload/park operations, eliminating the need for firmware to track head state. The physical system self-monitors its own position through the sensor, making the control firmware redundant for this specific function and thereby improving reliability.
2Device complexity
If ramp location is determined without precise detection, then device complexity is reduced, but manufacturing precision deteriorates due to inability to maximize usable disk space
Solution Approach 1:
The patent replaces complex mechanical positioning systems with a simple electrical sensor (fly height sensor) that electrically detects head-ramp contact. This sensor-based approach substitutes mechanical measurement methods with an electrical field-based detection method, achieving precise ramp location detection while keeping the system relatively simple.
3Duration of action of moving object
If fly height is not decreased for ramp detection, then head wear is reduced, but measurement precision deteriorates due to inability to detect ramp contact
Solution Approach 1:
The fly height sensor provides continuous feedback about the head's distance from the disk surface. During ramp detection, when the head contacts the ramp, the fly height signal changes, providing feedback that confirms ramp contact. This feedback mechanism enables precise detection while allowing the head to maintain appropriate fly height during normal operations, thus extending head service life.
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 solution enables reliable detection of the head's parked state and ramp location, preventing failures and maximizing disk space usage by accurately determining when the head contacts the ramp, thereby ensuring proper head positioning and data track alignment.
Implementation Method 1
utilizing temperature-sensitive sensors and calibration procedures to ensure accurate ramp detection
Data Source
AI summary
A disk drive is disclosed comprising a head actuated over a disk surface, the head comprising a temperature sensitive (TS) fly height sensor. The disk drive further comprises a ramp for parking the head, and control circuitry configured to process a fly height signal generated by the TS fly height sensor, wherein the fly height signal represents a fly height of the head over the disk, and detect whether the head is on the ramp in response to the fly height signal.