Imaging Apparatus Floating Diffusion Capacitance Dynamic Range
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Solution Overview
Problem
Existing imaging apparatuses with global electronic shutter functions do not effectively explore the relationship between dynamic range extension and capacitance values of input nodes in amplifying units, leading to limitations in signal processing and image quality.
Innovation Solution
The imaging apparatus employs a configuration with different capacitance values for floating diffusion capacitances in unit cells, allowing for synchronized electronic shutter and global transfer operations, which enables the extension of dynamic range by optimizing signal accumulation periods and reducing noise components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If different capacitance values are used for floating diffusion capacitances in unit cells, then dynamic range is extended, but device complexity increases
Solution Approach 1:
The imaging apparatus divides the pixel array into multiple unit cells, where each unit cell contains floating diffusion capacitances with different capacitance values. This segmentation allows different regions to handle different signal levels, extending the overall dynamic range of the imaging apparatus.
Solution Approach 2:
Different floating diffusion capacitances within unit cells are assigned different capacitance values to optimize signal handling for specific local regions. This local quality approach ensures that each capacitance is tailored to its specific function, improving signal-to-noise ratio and extending dynamic range.
2Ease of operation
If global electronic shutter function is implemented, then signal accumulation control is improved, but device complexity increases
Solution Approach 1:
The global electronic shutter function is implemented by preliminarily setting the floating diffusion capacitances in a reset state before signal accumulation begins. This preliminary action allows synchronized control of signal accumulation across all unit cells, improving operational control while managing complexity through systematic initialization.
Solution Approach 2:
The floating diffusion capacitances serve multiple functions: they act as signal holding units during accumulation, as resettable storage elements for the global electronic shutter, and as signal transfer nodes to the photoelectric converting units. This multi-functionality reduces the need for separate dedicated components, managing device complexity.
3Measurement precision
If multiple signal holding units are used with different impedances, then signal sensitivity is optimized, but device complexity increases
Solution Approach 1:
Different floating diffusion capacitances are assigned different capacitance values based on their specific signal handling requirements. This local optimization ensures that each capacitance is matched to its signal characteristics, improving signal sensitivity and noise performance for different signal levels.
Solution Approach 2:
The capacitance values of floating diffusion capacitances are varied across different unit cells to optimize signal holding characteristics. By changing this electrical parameter, the system achieves different signal sensitivities and dynamic ranges without adding complex control mechanisms.
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 effectively extends the dynamic range of images by allowing for accurate signal processing across varying light conditions, reducing brightness variations and improving image quality by synchronizing signal accumulation periods and noise management.
Implementation Method 1
Each unit cell 20 has a photodiode 1 serving as a photoelectric converting unit
Implementation Method 2
The capacitor element 83 has one terminal electrically connected to the input node 85
Data Source
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AI summary
An imaging apparatus includes a plurality of groups one of a part of which has a capacitance changing unit configured to change a capacitance value of an input node (5, 15).