Displacement Sensor Offset Reduction via Charge Adjustment
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Solution Overview
Problem
Magnetic recording media in hard disk storage devices face performance issues due to noise and vibration, leading to random radial displacement and eccentricity, which affect read/write capabilities and signal-to-noise ratio.
Innovation Solution
A device with displacement measurement circuitry and charge adjuster circuitry is used to measure and compensate for ambient noise, allowing for accurate determination of both repetitive and non-repetitive run-out in rotating disks by forming an electric field and using oversampling to enhance signal resolution and remove noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the size and distance between magnetic elements are reduced to increase storage density, then the storage capacity increases, but the signal-to-noise ratio deteriorates and read/write performance decreases
Solution Approach 1:
The patent introduces an intermediary measurement system (displacement sensor with charge adjuster circuitry) that measures the position of the spin axis and compensates for runout effects. This intermediary measurement allows the system to distinguish between actual data signals and noise caused by mechanical imperfections, thereby maintaining signal-to-noise ratio even as magnetic elements are reduced in size
Solution Approach 2:
The patent implements a feedback mechanism where the displacement sensor continuously monitors spin axis position and the measured runout data is used to adjust the read/write head positioning or signal processing. This feedback loop compensates for the deteriorating signal quality by dynamically correcting for mechanical variations, enabling reliable reading of densely packed magnetic elements
2Productivity
If disk rotation speed is increased to improve data access speed, then productivity increases, but noise and vibration increase causing non-repetitive run-out and measurement difficulty
Solution Approach 1:
The patent replaces direct mechanical measurement methods with an electrical field-based displacement sensor that uses capacitive coupling to measure spin axis position. This substitution eliminates the need for physical contact or mechanical coupling, thereby avoiding the introduction of additional noise and vibration while enabling accurate measurement even at high rotation speeds
Solution Approach 2:
The patent employs periodic sampling of the displacement signal at specific phases of the disk rotation. By measuring at consistent rotational positions and using oversampling techniques, the system can distinguish between periodic runout (which repeats each rotation) and non-repetitive noise, thereby maintaining measurement accuracy despite increased vibration at higher rotation speeds
3Measurement precision
If ambient noise is measured and compensated for displacement measurement, then measurement precision improves, but device complexity increases due to additional circuitry
Solution Approach 1:
The patent combines the displacement measurement function and ambient noise measurement function into a single integrated sensor system. The same capacitive sensor elements are used to measure both the spin axis position and the ambient electrical noise, eliminating the need for separate measurement circuits and reducing overall device complexity while maintaining high measurement precision
Solution Approach 2:
The displacement sensor circuit is designed with multi-functionality, serving both as a primary displacement measurement device and as an ambient noise detector. The charge adjuster circuitry can operate in different modes to either measure displacement directly or to characterize ambient noise for subsequent compensation, thereby achieving dual functionality without requiring separate dedicated circuits for each function
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 improves the accuracy of displacement measurement by reducing ambient noise, enhancing the signal-to-noise ratio and compensating for offsets, thereby improving the performance and reliability of magnetic recording media.
Implementation Method 1
forming an electric field and using oversampling to enhance signal resolution
Implementation Method 2
The charge adjuster circuitry is configured to adjust sensors of the displacement measurement circuitry to reduce the measured offset
Data Source
AI summary
A device including a displacement measurement circuitry and a charge adjuster circuitry is disclosed. The displacement measurement circuitry may be configured to measure displacement associated with a rotating object. The charge adjuster circuitry is coupled to the displacement measurement circuitry. The charge adjuster circuitry is configured to measure an offset associated with ambient noise in the device over time. The charge adjuster circuitry is further configured to adjust sensors of the displacement measurement circuitry to reduce the measured offset.