Multi-Photodetector Pixel for Extended Dynamic Range Imaging
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Solution Overview
Problem
Current imaging technologies face challenges in capturing images with high sensitivity and resolution over a wide dynamic range, as existing methods either introduce artifacts or impose significant cost and complexity, particularly as pixel sizes shrink.
Innovation Solution
The implementation of a multi-photodetector pixel configuration with independent control of charge accumulation and a gain capacitor, allowing for multiple integration times and charge binning, enabling a wide dynamic range within single image frames.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple images with different exposure times are acquired and combined, then dynamic range is extended, but image resolution and quality deteriorate due to artifacts
Solution Approach 1:
The pixel is segmented into multiple independent photodetectors (first and second photodetectors) within a single pixel unit, each capable of independent charge accumulation with different integration times. This segmentation allows simultaneous capture of different exposure data without requiring multiple separate images, thereby extending dynamic range while maintaining image resolution and avoiding artifacts from combining multiple images.
Solution Approach 2:
The invention adds a temporal dimension to the pixel structure by enabling different integration times for different photodetectors within the same pixel. This dimensional expansion allows the system to capture both bright and dark scene regions simultaneously in a single exposure cycle, achieving extended dynamic range without the quality degradation associated with multi-image combination methods.
2Productivity
If pixel sizes are reduced to increase array integration, then sensitivity and resolution deteriorate due to reduced signal output
Solution Approach 1:
The invention merges multiple photodetectors within a single pixel unit, allowing their signals to be combined through charge binning. This merging approach enables smaller pixel sizes to achieve the same or better sensitivity by combining the output of multiple photodetectors, thus maintaining measurement precision while increasing array integration and productivity.
Solution Approach 2:
Each pixel unit becomes multi-functional by incorporating multiple photodetectors that can operate independently or in combination. The pixel can function as multiple separate detectors for high-resolution imaging or merge their signals for enhanced sensitivity in low-light conditions, providing universal functionality that maintains sensitivity regardless of pixel size reduction.
3Adaptability or versatility
If multiple detectors are used to capture different exposure copies, then dynamic range is extended, but device complexity and cost increase
Solution Approach 1:
The pixel is segmented into multiple photodetectors that are integrated within a single pixel unit, eliminating the need for separate detector systems. This segmentation approach extends dynamic range while keeping device complexity low by incorporating multiple detectors in a unified, compact structure that can be manufactured using standard CMOS processes.
Solution Approach 2:
The invention merges multiple photodetectors and their associated readout circuits into a single integrated pixel unit, reducing overall device complexity. By combining multiple detectors and their control logic within one pixel, the system achieves extended dynamic range without requiring separate detector systems, thereby reducing complexity and cost.
4Adaptability or versatility
If comparator circuits are used for saturation detection and reset, then dynamic range is extended, but device complexity increases
Solution Approach 1:
The pixel circuit performs saturation detection and automatic reset functions through its inherent charge accumulation mechanism, eliminating the need for external comparator circuits. The photodetectors and associated circuits automatically detect saturation conditions and reset themselves, extending dynamic range while reducing device complexity by removing dedicated comparator components.
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 effectively captures images with a dynamic range of up to 10,000,000:1, improving image quality by handling high and low signal outputs simultaneously without introducing unwanted artifacts or excessive cost, suitable for various applications including surveillance and medical imaging.
Implementation Method 1
two or more photodiodes formed in the substrate that are configured to integrate charge generated due to incident light
Data Source
AI summary
An imaging system for capturing light over a wide dynamic range and method for operating the same are provided. In some aspects, the method includes positioning an imaging pixel to image a scene described by light signals that extend over a wide dynamic range, and selecting a different integration time for at least two photodiodes in the imaging pixel based on light signals received by the imaging pixel, wherein the photodiodes are coupled to a sense node, and each photodiode is controlled using a different transfer gate. The method also includes performing a readout of the imaging pixel using a readout circuit connected to the sense node, wherein a capacitance associated with the sense node is modified during the readout of the at least two photodiodes.