Single-Ended Amplifier Idle-Channel Noise Offset for Haptic Sensing
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Solution Overview
Problem
Existing methods for sensing displacement in haptic transducers, such as Hall sensors, are costly and inefficient, leading to variations in vibration resonance due to sample-to-sample variations and aging, which affect the accuracy of haptic feedback in portable devices.
Innovation Solution
A system with a current-sensing circuit and a voltage-mode driver that creates a signal offset during idle channel mode to minimize noise, allowing for precise measurement of displacement and inductance, enabling accurate control of haptic transducers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Hall sensors are used to measure displacement, then measurement capability is provided, but cost increases and efficiency decreases
Solution Approach 1:
The patent replaces mechanical Hall sensors with an electrical measurement system that uses current sensing circuits and inductance measurement to determine displacement. The system measures the inductance of the voice coil motor, which changes with displacement, and uses this electrical parameter to calculate position without requiring physical sensors.
Solution Approach 2:
The patent introduces an intermediary measurement approach by using the electrical properties (inductance) of the voice coil motor as a mediator to infer displacement. Instead of directly measuring physical position with a sensor, the system measures electrical inductance changes that correlate with displacement, providing an indirect but effective measurement method.
2Measurement precision
If sample-to-sample variations and aging are not compensated, then device complexity is reduced, but vibration resonance accuracy deteriorates
Solution Approach 1:
The patent implements feedback by continuously measuring the inductance of the voice coil motor and using this information to compensate for variations in vibration resonance characteristics. The system monitors electrical parameters and adjusts control signals based on measured deviations, creating a closed-loop system that maintains accuracy despite aging and manufacturing variations.
Solution Approach 2:
The patent utilizes parameter changes in the electrical characteristics of the voice coil motor, specifically inductance, to track and compensate for displacement and resonance variations. By monitoring how electrical parameters change with position and aging, the system adapts its control to maintain accurate vibration resonance without requiring complex mechanical compensation mechanisms.
3Measurement precision
If idle channel noise is not minimized, then circuit complexity is reduced, but displacement measurement accuracy deteriorates
Solution Approach 1:
The patent extracts and separates the noise signal from the measurement signal by using dedicated idle channel noise minimization circuitry. The system identifies and removes noise components from the current sensing path, isolating the true displacement-related signals for accurate measurement while filtering out spurious noise that would otherwise corrupt the data.
Data Source
AI summary
In accordance with embodiments of the present disclosure, a system may include a driver configured to drive a load with a single-ended driving signal and a signal return path for the load, wherein the signal return path comprises a voltage-mode driver configured to create a signal offset during an idle channel mode of the system in order to minimize idle channel noise at the load.