Pixel AD Conversion Circuit for Signal Range and Time Trade-off
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Solution Overview
Problem
Existing imaging systems face challenges in balancing the accuracy of converting photoelectric conversion signals with different viable signal ranges into digital signals while also shortening the time required for this conversion.
Innovation Solution
The imaging apparatus employs a configuration where signals from a subset of photoelectric conversion units are converted into digital signals in a shorter period than those from the full set, utilizing a microlens array and intra-pixel readout circuits with transfer MOS transistors, reset, and amplifier MOS transistors to manage signal charges and convert them efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If signals from all photoelectric conversion units are converted to digital signals with high accuracy, then conversion accuracy is improved, but conversion time increases
Solution Approach 1:
The patent divides the photoelectric conversion units into multiple groups (first photoelectric conversion units and second photoelectric conversion units) with different photoelectric conversion characteristics. Each group has its own signal charge storage region and transfer path, allowing independent readout and conversion. This segmentation enables parallel processing of signals from different groups, reducing overall conversion time while maintaining accuracy for each group's specific signal range.
Solution Approach 2:
The patent implements dynamic control of signal charge transfer timing for different photoelectric conversion unit groups. The transfer timing is optimized based on the specific viable signal range and photoelectric conversion characteristics of each group. This dynamic approach allows the system to adapt the conversion process to the actual signal characteristics, achieving both high accuracy and reduced conversion time by processing different groups at optimally timed intervals.
2Adaptability or versatility
If photoelectric conversion units with larger surface areas are used, then viable signal range is improved, but signal charge capacity for high-precision conversion is reduced
Solution Approach 1:
The patent assigns different photoelectric conversion characteristics (different surface areas) to different groups of photoelectric conversion units within the same pixel. The first photoelectric conversion units have one set of characteristics optimized for certain signal ranges, while the second photoelectric conversion units have different characteristics optimized for other signal ranges. This local differentiation of quality allows the system to handle diverse signal conditions with appropriate specialized units, achieving both wide viable signal range and high conversion accuracy for 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
This approach allows for accurate digital conversion of signals while reducing the overall conversion time, enhancing the system's efficiency and performance in handling signals with varying dynamic ranges.
Implementation Method 1
a first photodiode which performs photoelectric conversion on incident light and generates a first signal charge
Data Source
AI summary
An imaging apparatus, driving method of the imaging apparatus, and an imaging system, are provided, wherein pixels output at least two image signals with different viable signal ranges, and the pixel signal with a larger signal range is converted to a digital signal during a first period, and the pixel signal with a smaller signal range is converted to a digital signal during a second period shorter than the first period.