Dual-Material ToF Image Sensor for Sunlight Noise Correction
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Solution Overview
Problem
Existing Time-of-Flight (ToF) systems are prone to interference from ambient light, particularly sunlight, which negatively impacts performance in outdoor environments due to high background noise and reduced signal-to-background noise ratio, especially when using germanium-based photodetectors.
Innovation Solution
Incorporating a dual-sensor architecture with primary sensors made from germanium-based materials for ToF measurement signals and secondary sensors made from silicon-based materials for background light detection, allowing for noise correction and improved accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If germanium-based photodetectors are used for ToF measurement, then sensitivity to infrared light is improved, but susceptibility to ambient light interference increases
Solution Approach 1:
The sensor array is segmented into multiple types of sensor elements: germanium-based photodetectors for ToF measurement and silicon-based photodetectors for background light detection. Each segment handles a specific function, allowing the system to distinguish between signal and noise by separating detection functions across different sensor types.
Solution Approach 2:
Silicon-based photodetectors act as intermediaries to detect ambient light levels. These secondary sensors measure the background noise component, which is then used to correct the measurements from the germanium-based primary sensors, effectively mediating the interference between the two sensor types.
2Device complexity
If single-sensor architecture is used, then device complexity is reduced, but noise correction capability is lost
Solution Approach 1:
Multiple sensor types (germanium-based and silicon-based photodetectors) are merged into a single integrated sensor array on one substrate. This combination allows the system to simultaneously perform ToF measurement and background noise detection, achieving noise correction capability without requiring separate devices.
Solution Approach 2:
The sensor array performs multiple functions: germanium-based photodetectors detect ToF signals while silicon-based photodetectors detect background light. This multi-functionality within a single integrated structure enables the system to correct for ambient light interference without adding separate external devices.
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 dual-sensor approach effectively mitigates the interference from sunlight, enhancing the accuracy and performance of ToF systems in outdoor conditions by correcting for background noise using secondary sensors.
Implementation Method 1
Each first sensor element includes a photodetector that includes a photovoltaic junction formed at least partially in a germanium-based material
Implementation Method 2
Each second sensor element includes a photodetector that includes a photovoltaic junction formed in a second material that includes silicon
Data Source
AI summary
An image sensor for a Time-of-Flight imaging system is disclosed that includes at least one primary sensor having a photodetector that includes a photovoltaic junction formed at least partially in a germanium-containing material that includes germanium at an atomic percentage greater than 50%, and at least one secondary sensor having a photodetector that includes a photovoltaic junction formed in a second material, such as a silicon-containing material, that includes germanium at an atomic percentage between 0% and 50%. The primary sensor may detect Time-of-Flight measurement signals and the secondary sensor may detect background light, such as sunlight, to correct for background light interference.