Event-Based Image Sensor Pixels for Dark Current Noise Correction
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Solution Overview
Problem
Asynchronous solid-state imaging elements, such as DVS, face challenges with dark current noise and offset noise, which degrade signal quality due to dark current and constant offset voltage generated in pixels, particularly in applications requiring fast image processing like traffic monitoring.
Innovation Solution
The implementation of open pixels to detect changes in incident light and light-blocked pixels to generate correction signals for noise removal, with the light-blocked pixels converting dark current to voltage signals and using quantizers to detect threshold changes, allowing for noise correction and improved signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If asynchronous solid-state imaging elements (DVS) are used to detect address events in real time, then the data generation speed and response time are significantly improved, but dark current noise and offset noise increase, degrading signal quality
Solution Approach 1:
The pixel array is divided into two distinct types: open pixels for detecting address events and light-blocked pixels for generating correction signals. This segmentation allows each pixel type to specialize in its function, enabling real-time event detection while separately generating noise correction data, thus resolving the contradiction between speed and signal quality
Solution Approach 2:
Light-blocked pixels act as an intermediary mechanism that generates correction signals representing noise characteristics. These correction signals mediate between the raw pixel signals and the final processed output, allowing noise removal without compromising the real-time detection capability of open pixels
2Reliability
If light-blocked pixels are added to generate correction signals, then signal quality is improved through noise removal, but device complexity increases
Solution Approach 1:
Different regions of the pixel array are assigned different functional qualities: open pixels have light-receiving structures optimized for event detection, while light-blocked pixels have light-blocking structures optimized for generating correction signals. This local differentiation achieves noise correction without requiring complete structural redesign of all pixels
Solution Approach 2:
Both open pixels and light-blocked pixels share common circuitry components such as photoelectric conversion elements and signal processing circuits. This multi-functionality allows the same basic structures to serve different purposes, reducing overall device complexity while still achieving noise correction functionality
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 configuration enhances signal quality by effectively removing dark current and offset noise from pixel signals, improving the detection accuracy and speed of address events in imaging devices.
Implementation Method 1
In the pixel, the photodiode sometimes outputs a current called a 'dark current' even when not receiving light
Data Source
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AI summary
The signal quality of a solid-state imaging element configured to detect address events is enhanced. The solid-state imaging element has open pixels and light-blocked pixels arrayed therein. In the solid-state imaging element, the open pixels each detect whether or not an amount of change in incident light amount exceeds a predetermined threshold, and output a detection signal indicating a result of the detection. On the other hand, in the solid-state imaging element, the light-blocked pixels each output a correction signal based on an amount of noise generated in the open pixels each configured to detect whether or not an amount of change in incident light amount exceeds the predetermined threshold and to output a detection signal indicating a result of the detection.