Global Shutter Pixel Dual Storage Architecture
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Solution Overview
Problem
Current global shutter pixel architectures face challenges in rapid image acquisition and are sensitive to parasitic light and dark current, leading to issues like blooming and temporal aliasing, especially in applications requiring quick ambient light detection and movement analysis.
Innovation Solution
A 10T pixel architecture with dual storage elements and independent readout capabilities, allowing for simultaneous exposure and independent storage and readout of two or more successive frames, reducing the impact of parasitic light and dark current through increased capacitance and separate reset of floating diffusion and photodiode nodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single storage element is used in each pixel for global shutter operation, then the pixel structure is simple, but the readout time becomes significantly longer than the exposure time, causing temporal delay between frames
Solution Approach 1:
The patent divides the single storage function into multiple storage elements (first and second storage elements) within each pixel. This segmentation allows simultaneous storage of multiple frames, enabling rapid sequential capture without temporal delay while maintaining simple pixel structure through systematic duplication of storage components.
2Productivity
If pixels are read out sequentially before the next signal can be acquired, then the readout process can be completed, but the readout time is significantly longer than the exposure time, preventing rapid image acquisition
Solution Approach 1:
The patent implements preliminary action by having pixels continuously capture and store multiple frames in advance using dual storage elements during the exposure period. This allows the sensor to be ready with pre-captured images, eliminating the temporal gap between exposure and readout, and enabling rapid image acquisition without waiting for sequential readout to complete.
3Manufacturing precision
If the exposure time is shortened to prevent motion blur, then motion blur is reduced, but the readout time remains significantly longer, creating a larger disparity between exposure and readout timing
Solution Approach 1:
The patent ensures continuity of useful action by maintaining continuous image capture through dual storage elements that allow overlapping exposure and readout operations. While one set of pixels is being read out, another set continues to expose and store frames, eliminating idle time and maintaining continuous productive operation regardless of exposure duration.
4Measurement precision
If a global shutter with simultaneous exposure is used, then motion detection accuracy is improved, but temporal aliasing occurs when structures move almost one complete cycle during the delay between frames
Solution Approach 1:
The patent applies dynamics by enabling flexible and independent control of exposure timing for different pixel groups. The system can dynamically adjust the timing of exposure and readout operations, allowing optimization of frame capture intervals to match the temporal frequency of moving objects, thereby preventing temporal aliasing while maintaining motion detection accuracy.
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 rapid acquisition of two images in less than 10 μs, reducing blooming and temporal aliasing, and improving sensitivity and accuracy for ambient light sensing and movement detection in machine vision applications.
Implementation Method 1
A 10T pixel architecture with dual storage elements and independent readout capabilities, allowing for simultaneous exposure and independent storage and readout of two or more successive frames
Data Source
AI summary
A sensor includes an array of pixels, and a global shutter configured to expose the array of pixels. Each pixel includes storage elements configured to independently store successive frames within a predetermined time period. Each storage element is configured to be independently read out.