Pixel Electron Exclusion Region Charge Transfer Optimization
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Solution Overview
Problem
Conventional pixels fail to accurately form images of moving objects with a wide dynamic range due to unclear relationships between photodiode shape and charge transfer time, and existing methods are either temperature-sensitive or inefficient in capturing moving objects.
Innovation Solution
A pixel design with an electron exclusion region within the photodiode region to reduce the width of the free electron passing region, allowing for optimized charge transfer time, combined with an imaging device and method that stores charge in multiple sections for different exposure times and illuminating conditions to form images with a wide dynamic range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the photodiode region shape is optimized to reduce charge transfer time, then charge transfer time is reduced, but the dynamic range and image accuracy for moving objects remain insufficient
Solution Approach 1:
The photodiode region is divided into multiple independent pixel units, each with its own photoelectric converting section and charge storage section. This segmentation allows parallel charge transfer operations across multiple pixels, reducing the effective charge transfer time while maintaining image quality through spatial distribution of the imaging function.
Solution Approach 2:
The imaging device employs periodic exposure operations with multiple charge storage sections that alternately accumulate charge during different time periods. By periodically switching between short-exposure and long-exposure accumulation, the system captures moving objects at different exposure moments, effectively reducing charge transfer time requirements while maintaining high image accuracy through temporal sampling.
2Ease of manufacture
If conventional pixels are used with standard photodiode shapes, then manufacturing is simpler, but charge transfer time is not optimized and image accuracy for moving objects deteriorates
Solution Approach 1:
The patent introduces an electron exclusion region with specific characteristics (different electron concentration or potential) within the photodiode region to create local quality variations. This localized modification optimizes the electric field distribution specifically in the charge transfer path, improving charge transfer efficiency and image accuracy without requiring complete redesign of the entire pixel structure, thus maintaining ease of manufacture.
Solution Approach 2:
The invention modifies specific parameters of the photodiode region, such as the electron concentration, potential distribution, or geometric dimensions of the photoelectric converting section and charge storage section. By changing these parameters locally within the pixel structure, the charge transfer time is optimized while maintaining compatibility with conventional manufacturing processes.
3Adaptability or versatility
If multiple charge storage sections are used with different exposure times, then wide dynamic range is achieved, but device complexity increases
Solution Approach 1:
Multiple charge storage sections are merged within a single pixel unit structure, sharing common elements such as the photoelectric converting section, readout circuitry, and control logic. This merging approach allows the pixel to achieve wide dynamic range through multiple exposure time accumulations while reducing overall device complexity by eliminating redundant components that would exist if separate pixels were used for each exposure time.
Solution Approach 2:
Each pixel unit is designed with multi-functionality, where the same photoelectric converting section can charge multiple charge storage sections with different exposure times. This universal design allows a single pixel structure to perform multiple imaging functions (short exposure, long exposure, different dynamic ranges) without requiring separate dedicated pixels for each function, thereby reducing device complexity.
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
The solution enables the formation of high-accuracy images of moving objects with a wide dynamic range by minimizing charge transfer time and utilizing differential charging operations across multiple charge storage sections.
Implementation Method 1
a photoelectric converting section which generates electrons when receiving light
Data Source
AI summary
A pixel is provided with a photodiode region which includes a photoelectric conversion portion for receiving light and generating electrons, and a charge storage portion for storing electric charge. The pixel is configured in such a manner that an electron exclusion region is provided in the photodiode region with the diameter of a circle having the maximum diameter among circles that can exist in the surface of a region through which electrons can pass in the photodiode region as the width of an electron passage region in the photodiode region, and the width of the electron passage region is smaller than when the electron exclusion region is not provided.