Global Shutter Sensor Distance Detection via Overlapping Exposure
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Solution Overview
Problem
Global shutter image sensors face challenges in detecting short pulses of infrared light due to their short exposure times, which limits sensitivity and precision in distance measurement, especially in applications like automotive where picosecond exposure times are required.
Innovation Solution
The method involves emitting an optical pulse and using multiple detectors with overlapping or offset exposure times to capture the reflected pulse, allowing for improved precision in distance calculation by analyzing the detector signals from each sensor, even with short exposure times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a gated CMOS sensor uses tens of picoseconds exposure time to capture reflected infrared light, then the speed of light detection is achieved, but the sensitivity is limited due to short photon capture times and the sensor design becomes complex
Solution Approach 1:
The patent divides the detection process into multiple segments by using multiple detectors (first detector, n-th detector, m-th detector) each with different exposure durations. This segmentation allows the system to capture the reflected optical pulse at different time intervals, effectively resolving the contradiction between short exposure time and detection sensitivity by accumulating information from multiple temporal segments.
Solution Approach 2:
The patent employs periodic action through multiple detectors with staggered exposure windows. Each detector operates in a periodic manner with overlapping exposure durations, allowing the system to sample the reflected pulse multiple times across different time periods. This periodic sampling approach maintains the required speed while improving sensitivity through cumulative detection.
2Measurement precision
If multiple detectors with overlapping exposure durations are used, then the signal-to-noise ratio and measurement precision are improved, but the device complexity increases
Solution Approach 1:
The patent merges the functionality of multiple detectors with different exposure durations into a unified distance detection system. By combining the detector signals through signal processing, the system achieves improved measurement precision while managing device complexity through integrated architecture. The merging of multiple detection channels allows information fusion that enhances accuracy.
Solution Approach 2:
The patent implements multi-functionality by designing a detector array where each detector serves multiple purposes: individual distance measurement, signal averaging for noise reduction, and temporal sampling of the reflected pulse. This universal approach allows the same hardware configuration to address both precision requirements and complexity constraints through versatile detector utilization.
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
This approach enhances the accuracy of distance measurement by increasing the pattern samples and signal-to-noise ratio, enabling more precise detection of distances without shortening the exposure time, thus overcoming the limitations of short exposure times in global shutter sensors.
Implementation Method 1
receiving at a first detector a reflected optical pulse
Implementation Method 2
determining the distance of an object based on the first detector signal and the n-th detector signal
Data Source
AI summary
A method of detecting a distance, comprising emitting an optical pulse, receiving at a first detector a reflected optical pulse, from a first exposure start time to a first exposure finish time, generating a first detector signal, receiving at an n-th detector the reflected optical pulse, from an n-th exposure start time to an n-th exposure finish time, generating an n-th detector signal, wherein the first exposure start time begins before the n-th exposure start time and the first exposure finish time ends before the n-th exposure finish time and the first exposure duration partially overlaps the n-th exposure duration and determining the distance of an object based on the first detector signal and the n-th detector signal.