Electrical Mixer Calibration for Time-of-Flight Distance Measurement
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Solution Overview
Problem
Time-of-flight imaging systems face calibration challenges due to temperature-dependent and supply voltage-dependent delays in the illumination component, which introduce errors in distance measurements and require complex calibration procedures, especially when drift compensation is needed.
Innovation Solution
An on-chip electrical mixer is used to multiply and filter signals, providing a calibration signal that compensates for the delay drift, allowing for in-line regulation and reducing the complexity and cost compared to reference pixel-based methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If reference pixel-based methods are used for calibration, then measurement precision can be maintained, but device complexity and cost increase
Solution Approach 1:
The patent extracts the calibration function from the pixel array by using a dedicated electrical mixer circuit that receives the modulation signal and illumination signal separately. This separation allows calibration to be performed using simple electrical signal processing rather than requiring complex optical reference paths through the pixel array, thereby reducing device complexity while maintaining measurement precision.
Solution Approach 2:
The patent introduces an electrical mixer as an intermediary component that bridges the modulation signal and illumination signal. This mixer performs the correlation function in the electrical domain rather than requiring optical interference measurements, simplifying the calibration process and reducing the need for complex post-processing while maintaining accurate delay measurement capability.
2Measurement precision
If complex calibration procedures are implemented to compensate for temperature and voltage drift, then measurement precision is improved, but ease of operation deteriorates
Solution Approach 1:
The patent implements self-service calibration by having the electrical mixer continuously process the modulation signal and illumination signal to generate real-time delay measurements. The system automatically compensates for temperature and voltage drift without requiring manual calibration interventions, making the operation simple while maintaining high measurement precision through continuous adaptive calibration.
Solution Approach 2:
The patent performs preliminary calibration by having the electrical mixer continuously measure the delay between modulation and illumination signals before actual distance measurements are taken. This ongoing preliminary calibration ensures that drift compensation is already in effect when measurements are performed, simplifying operation while maintaining precision.
3Measurement precision
If post-processing is used for calibration, then measurement precision can be achieved, but loss of time increases
Solution Approach 1:
The patent maintains continuity of useful action by having the electrical mixer continuously process the modulation and illumination signals to generate real-time delay measurements. This continuous calibration process eliminates the need for separate post-processing steps, as the calibration data is generated and available immediately alongside the measurement data, thereby maintaining precision without time loss.
Solution Approach 2:
The patent performs calibration measurements preliminarily and concurrently with the main measurement process through the electrical mixer. The delay measurement is generated in real-time during signal acquisition rather than requiring subsequent processing, eliminating time loss while maintaining measurement precision.
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
The on-chip electrical mixer effectively compensates for delay drift, providing a calibration signal that can be used immediately, reducing the need for post-processing and enabling accurate distance measurements while simplifying the calibration process and reducing costs.
Implementation Method 1
multiply the electrical illumination signal and the modulation signal in order to form a mixed signal
Implementation Method 2
filter the mixed signal in order to form a filtered mixed signal
Data Source
AI summary
An imaging system may include a modulation component to provide a modulation signal. The imaging system may include an illumination component to receive the modulation signal and emit a modulated optical signal based on the modulation signal, and provide an electrical illumination signal. The electrical illumination signal may be an electrical representation of the modulated optical signal emitted by the illumination component. The imaging system may include an electrical mixer to receive the electrical illumination signal and the modulation signal, multiply the electrical illumination signal and the modulation signal in order to form a mixed signal, filter the mixed signal in order to form a filtered mixed signal, and output, based on the filtered mixed signal, a calibration signal associated with calibrating the imaging system.