Photon-Counting Image Sensor Flickering Light Detection
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Solution Overview
Problem
Conventional photon-counting image sensors lack the ability to detect flickering light sources and characterize their characteristics, such as presence and brightness changes, which can affect image capture and processing.
Innovation Solution
An image capture apparatus with a two-dimensionally arranged pixel area, each pixel equipped with a light-receiving circuit generating pulse signals and a counting circuit, along with a detection circuit that identifies flickering light sources based on pulse signal frequency, and a control circuit that integrates count values accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional photon-counting image sensors are used, then photon counting capability is achieved, but flickering light source detection capability is lost
Solution Approach 1:
The pixel array is divided into multiple pixel groups, with each group containing multiple pixels that share common signal lines. This segmentation allows independent processing of flickering detection at the group level while maintaining photon counting at the pixel level, resolving the contradiction between precise photon counting and flickering detection capability.
Solution Approach 2:
A flickering detection circuit is introduced as an intermediary component between the pixel array and the image processing unit. This circuit receives pulse signals from pixel groups and generates flickering detection signals, enabling flickering light source detection without interfering with the primary photon counting function of individual pixels.
2Productivity
If signal accumulation time is shortened, then image capture speed is improved, but influence of flickering light cannot be suppressed
Solution Approach 1:
The flickering detection circuit performs preliminary detection of flickering light sources using pulse signals from pixel groups before the main image capture process. By detecting flickering characteristics in advance and generating control signals, the system can suppress flickering influence during subsequent image capture even with short accumulation times.
Solution Approach 2:
The flickering detection circuit continuously monitors pulse signal characteristics from pixel groups and generates feedback control signals to the image processing unit. This feedback mechanism enables real-time suppression of flickering light influence during image capture, allowing short accumulation times while maintaining image quality.
3Measurement precision
If pixel-level processing is used, then image resolution is maintained, but processing complexity increases
Solution Approach 1:
The processing system is segmented into multiple functional levels: pixel-level photon counting, pixel group-level flickering detection, and image-level processing. This segmentation distributes computational complexity across different levels, maintaining image resolution through pixel-level data while reducing overall processing complexity through group-level aggregation and centralized flickering detection.
Solution Approach 2:
Multiple pixels are merged into pixel groups that share common signal lines and processing paths. This merging reduces the number of independent processing channels, thereby reducing overall processing complexity while preserving image resolution through the aggregated data from multiple pixels within each group.
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
Enables effective detection and characterization of flickering light sources, improving image capture by integrating count values to suppress the influence of flickering light, even when the signal accumulation time is shorter than the brightness change period.
Implementation Method 1
avalanche photodiodes (APD) to which a reverse bias voltage larger than a breakdown voltage is applied
Implementation Method 2
each of the pixels has a light-receiving circuit that outputs a pulse signal in response to incidence of a photon
Data Source
AI summary
An image capture apparatus comprising a plurality of pixels, each pixel having a light-receiving circuit that outputs a pulse signal in response to incidence of a photon and a counting circuit configured to count the pulse signal, is disclosed. The image capture apparatus further comprises a detection circuit that detects whether or not a flickering light source is present in a field of view, based on an output frequency of the pulse signal.