Resonant MEMS Mirror Digital Parameter Estimation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Resonant systems, such as scanning laser projectors, face challenges in accurately estimating the position of resonating mirrors due to variations in component characteristics over time, temperature, and age, which limits image resolution.
Innovation Solution
The implementation of digital parameter estimation circuits, including a buffer, analog anti-aliasing filter, ADC, digital anti-aliasing filter, down-sampler, bandpass filter, up-sampler, and spectral replica filter, along with interpolating zero-crossing and peak amplitude estimators, reduces phase shifts and enhances estimation accuracy, allowing for increased image resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If analog parameter estimation circuits (filters, comparators, peak detectors) are used, then the circuit can estimate mirror position parameters, but manufacturing variations and environmental drifts limit the estimation accuracy and image resolution
Solution Approach 1:
The patent replaces analog electronic circuits with digital signal processing techniques. Specifically, it uses digital filtering (FIR/IIR filters), digital peak detection algorithms, and digital signal analysis to estimate mirror position parameters. This substitution eliminates the manufacturing variations and environmental drifts inherent in analog components while maintaining the ability to estimate oscillation amplitude, phase shift, and period with higher precision and stability
Solution Approach 2:
The patent changes the operating parameters of the estimation system by using digital signal processing with adjustable filter coefficients, sampling rates, and analysis algorithms. This allows dynamic adaptation to different operating conditions and resonance frequencies without being constrained by fixed analog component characteristics, thereby improving both measurement precision and reliability
2Measurement precision
If analog filters are used for signal processing, then the circuit can extract resonance parameters, but phase drift over temperature and frequency limits position estimation accuracy
Solution Approach 1:
The patent replaces analog filters with digital filtering techniques including FIR (Finite Impulse Response) and IIR (Infinite Impulse Response) filters implemented in software or digital signal processors. These digital filters provide stable frequency and phase responses that do not drift with temperature or manufacturing variations, enabling accurate resonance parameter extraction and mirror position estimation across varying environmental conditions
3Measurement precision
If analog comparators are used for peak detection, then the circuit can estimate oscillation parameters, but manufacturing variation and threshold drift limit estimation accuracy
Solution Approach 1:
The patent replaces analog comparators with digital signal processing algorithms for peak detection. The system digitizes the feedback signal and uses digital algorithms to identify oscillation peaks, measure amplitudes, and determine phase shifts. This eliminates sensitivity to comparator threshold drift and manufacturing variations, providing consistent and accurate parameter estimation
Solution Approach 2:
The patent creates a digital copy of the analog feedback signal through ADC (analog-to-digital conversion). This digital replica can be processed without the imperfections of analog components, allowing accurate parameter extraction while isolating the measurement process from manufacturing variations and environmental drifts affecting physical comparator circuits
4Measurement precision
If analog peak-detector circuits are used, then the circuit can detect oscillation amplitude, but aliasing and ripple problems reduce measurement accuracy
Solution Approach 1:
The patent replaces analog peak-detector circuits with digital signal processing techniques that include proper anti-aliasing filtering before ADC conversion and digital signal processing algorithms for amplitude measurement. This substitution eliminates aliasing errors and ripple effects inherent in analog peak detectors, providing accurate and stable oscillation amplitude measurements
Solution Approach 2:
The patent applies anti-aliasing filters before the ADC conversion stage to pre-process the signal and remove frequency components that would cause aliasing. This preliminary action prevents aliasing errors from occurring in the first place, ensuring accurate amplitude measurement without the need for complex correction algorithms
Data Source
AI summary
A resonant scanning mirror includes a sensor to provide position information. A parameter estimation circuit estimates parameters from the position information. The parameter estimation circuit includes wideband analog circuits that have poles far removed from the resonant frequency of the scanning mirror. The parameter estimation circuit also includes an analog-to-digital converter that samples at a high sample rate, and digital filters that exhibit near perfect linearity.