High Dynamic Range Image Sensor Blinking Light Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional high dynamic range image sensors struggle to reliably detect blinking light sources due to their limited ability to capture the full illumination range, especially in scenes with high contrast and pulsed light sources, often resulting in missed detection or incorrect detection of blinking light sources.
Innovation Solution
The proposed solution involves an image sensor with multiple photodiodes and a control circuit that acquires illumination values during different integration periods, with the second and third photodiodes having integration periods divided into separate sub-periods, allowing for improved detection of blinking light sources by increasing the chances of capturing the light source's on phase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a single long integration period is used to capture low illumination levels, then the dynamic range is improved, but blinking light sources are missed because the light source may be off during the entire integration period
Solution Approach 1:
The pixel is divided into multiple photodiodes (e.g., first photodiode with long integration period, second photodiode with short integration period) that simultaneously capture illumination at different exposure levels. This segmentation allows the system to capture both low illumination levels (dark areas) and high illumination levels (blinking light sources) within the same acquisition phase, resolving the contradiction between dynamic range and detection reliability.
Solution Approach 2:
The invention uses multiple integration periods with different durations (e.g., long integration period TL, medium integration period TM, short integration period TS) to sample the scene at different exposure levels. By using periodic acquisition phases with multiple integration periods, the system increases the probability of capturing blinking light sources in at least one of the integration periods, while maintaining the ability to capture dark areas with the long integration period.
2Illumination intensity
If multiple images with different exposure times are acquired successively to create high dynamic range image, then the dynamic range is improved, but the acquisition time increases and blinking light sources may be missed between acquisition phases
Solution Approach 1:
The invention merges multiple integration periods (long, medium, short) into a single simultaneous acquisition phase. All photodiodes integrate their respective exposure periods concurrently within one acquisition phase Tframe, eliminating the need for successive acquisitions. This reduces the total acquisition time while maintaining high dynamic range capability and improving detection of blinking light sources.
Solution Approach 2:
The system performs preliminary integration of different exposure periods within the same acquisition phase, preparing multiple exposure levels in parallel rather than sequentially. This preliminary action within a single frame allows the system to capture the full dynamic range without extending the acquisition time across multiple frames.
3Illumination intensity
If the integration period is extended to capture low illumination levels, then the dynamic range is improved, but the photodiode saturates during the integration period and cannot detect blinking light sources
Solution Approach 1:
Different photodiodes are assigned different integration period qualities tailored to their specific detection needs. The first photodiode uses a long integration period optimized for capturing low illumination levels, while the second photodiode uses a short integration period optimized for capturing high illumination levels without saturation. This local quality differentiation allows each photodiode to excel at its specific function, resolving the contradiction between dynamic range and detection precision.
Solution Approach 2:
The pixel is segmented into multiple photodiodes with different integration period characteristics. This segmentation allows the system to simultaneously maintain a long integration period for low illumination capture and a short integration period for high illumination capture, preventing saturation while preserving dynamic range capability.
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 reliability of detecting blinking light sources by ensuring that part of the light emitted during the acquisition phase contributes to the final output value, improving detection performance while maintaining a high dynamic range.
Implementation Method 1
each comprising a photodiode and a control circuit capable of delivering an output signal representative of the illumination level received by its photodiode
Data Source
AI summary
The present disclosure relates to an image sensor including: a plurality of pixels, each including a first photodiode coupled to a first capacitive charge storage node by a first transistor, and a second photodiode coupled to a second capacitive charge storage node by a second transistor; and a control circuit configured so as to, during a phase of acquisition of a value representative of the illumination level of a pixel: acquire a first output value representative of the illumination level received by the first photodiode during a first uninterrupted integration period; and acquire a second output value representative of the illumination level received by the second photodiode during a second integration period divided into a plurality of separate sub-periods.