SPAD Array Image Sensor Chip Depth Measurement Noise Reduction
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Solution Overview
Problem
Single Photon Avalanche Diode (SPAD) detectors are overly sensitive to light and environmental noise, leading to inaccurate photon detection and high data output delays, especially when used for wide-range photon detection.
Innovation Solution
An image sensor chip architecture incorporating a SPAD array, Time-to-Digital Converter (TDC) module, and data processing circuit, where each image sensor unit determines photon detection based on multiple SPAD units and employs data compression to reduce output bandwidth and increase speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If SPAD detectors are used to detect weak light signals, then detection sensitivity is improved, but detection accuracy deteriorates due to excessive sensitivity to environmental noise
Solution Approach 1:
Multiple SPAD units are merged into image sensor units with shared decision circuits. The decision circuit combines photon detection results from multiple SPAD units using logical operations (AND/OR) to generate image-sensing signals, thereby reducing noise impact while maintaining sensitivity
Solution Approach 2:
The system implements feedback through decision circuits that process photon detection results from multiple SPAD units. The decision circuit uses logical operations to evaluate multiple detection results before generating the final image-sensing signal, providing a feedback mechanism to filter out erroneous noise detections
2Adaptability or versatility
If multiple SPAD units are used for wide-range photon detection, then detection coverage is improved, but data output delay worsens due to huge data volume
Solution Approach 1:
Multiple SPAD units within each image sensor unit share common decision circuits and TDC resources. This merging reduces the total number of independent data processing paths, thereby reducing overall data output volume and delay while maintaining wide detection coverage through the array of image sensor units
Solution Approach 2:
The decision circuit and TDC module are designed as multi-functional units that serve multiple SPAD units. Each decision circuit can process photon detection results from multiple SPAD units, and the TDC module generates time data for multiple image sensor units, reducing redundant circuitry and data processing overhead
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 solution enhances the accuracy of light detection for high-precision depth measurement while rapidly outputting measurement results, reducing erroneous noise interference and data output delays.
Implementation Method 1
Single Photon Avalanche Diode (SPAD) detectors are overly sensitive to light and environmental noise
Data Source
AI summary
An image sensor chip with depth information is provided. The image sensor chip includes an SPAD array, a time-to-digital converter module, a storage circuit, and a data processing circuit. The SPAD array includes a plurality of image sensor units, and each of the image sensor units includes a plurality of SPAD units and a decision circuit, wherein each of the SPAD units outputs a photon detection result within a scan period, and the decision circuit generates an image-sensing signal based on the photon detection results. The time-to-digital converter module generates a plurality of first time data in response to the image-sensing signals. The storage circuit stores the first time data temporarily. The data processing unit reads the first time data from the storage circuit and generates a plurality of second time data in response to the first time data.