ToF Sensing With CW and Coded Modulation for Ambiguity
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Solution Overview
Problem
Conventional Continuous Wave (CW) ToF sensing is plagued by distance ambiguities and stray light issues, while coded modulation (CM) approaches limit measurement range and increase exposure time, leading to motion blur and other disadvantages.
Innovation Solution
A method and apparatus that combines CW and CM measurements to determine distance values using a mapping function, incorporating error corrections to mitigate errors and adjust sensitivity, allowing for reduced measurement numbers and resolving distance ambiguities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional CW ToF sensing is used, then the measurement process is simple, but distance ambiguities and stray light issues occur
Solution Approach 1:
The patent combines CW and CM measurement approaches into a unified system. The processing circuit integrates results from both measurement types to determine final distance values, leveraging the simplicity of CW measurements while incorporating the ambiguity-resolution capability of CM measurements to eliminate distance ambiguities and stray light issues.
2Measurement precision
If conventional CM ToF sensing is used, then distance ambiguities are avoided, but measurement range is limited and exposure time increases
Solution Approach 1:
The patent merges CW and CM measurements to achieve a balance between exposure time and measurement accuracy. By combining the faster CW measurements with selective CM measurements, the system reduces overall exposure time compared to pure CM approaches while maintaining the ability to resolve distance ambiguities through the mapping function that processes both measurement types.
3Measurement precision
If conventional CM ToF sensing is used, then distance ambiguities are resolved, but motion blur increases
Solution Approach 1:
The patent combines CW and CM measurements where CW provides faster acquisition reducing motion blur, and CM provides ambiguity resolution. The processing circuit integrates both measurement types to produce final distance values that maintain image stability while resolving distance ambiguities, achieving both goals simultaneously through the synergistic combination of measurement approaches.
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 combined approach reduces the number of ToF measurements, minimizes erroneous reflections, and enhances measurement accuracy by compensating for errors, thus improving depth calculation and reducing exposure time limitations.
Implementation Method 1
Time-of-flight sensing using continuous wave and coded modulation measurements
Implementation Method 2
conventional four-phase Continuous Wave (CW) ToF sensing
Data Source
AI summary
A method for time-of-flight sensing is provided. The method includes for at least one pixel position performing at least one continuous wave measurement to obtain at least one first measurement value for the pixel position. Further, the method includes performing at least one coded modulation measurement to obtain at least one second measurement value for the pixel position. The method additionally includes determining an estimate of a distance value of the pixel position based on the at least one first measurement value and the at least one second measurement value using a mapping function.