Pixel Cell Signal Detection Circuit for Wide Dynamic Range Imaging
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Solution Overview
Problem
Existing imaging devices face challenges in achieving a wide dynamic range while maintaining image quality, as they require separate exposure periods for high-sensitivity and low-sensitivity signals, leading to potential deterioration in image quality and increased complexity.
Innovation Solution
The imaging device incorporates a pixel cell configuration with a photoelectric converter and a signal detection circuit that includes transistors and capacitors, allowing for the simultaneous generation of high-sensitivity and low-sensitivity signals within a single frame period, enabling identical exposure periods and reduced noise cancellation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If separate exposure periods are used for high-sensitivity and low-sensitivity signals, then dynamic range is improved, but image quality deteriorates and device complexity increases
Solution Approach 1:
The pixel cell is segmented into multiple photoelectric converters with different sensitivity levels (first photoelectric converter and second photoelectric converter). Each converter is connected to signal detection circuits that can selectively output signals based on lighting conditions. This segmentation allows simultaneous capture of both high-sensitivity and low-sensitivity signals within a single exposure period, resolving the contradiction between extended dynamic range and maintained image quality.
2Adaptability or versatility
If separate exposure periods are used for high-sensitivity and low-sensitivity signals, then dynamic range is improved, but device complexity increases
Solution Approach 1:
Multiple photoelectric converters and their associated signal detection circuits are merged within a single pixel cell structure. The first and second photoelectric converters share common circuit elements and output pathways, allowing the system to achieve wide dynamic range functionality without requiring separate imaging devices or complex external processing systems. This merging reduces overall device complexity while maintaining the capability to capture both high and low sensitivity signals simultaneously.
3Adaptability or versatility
If electronic shutter operation is performed twice with different periods, then dynamic range is enlarged, but productivity decreases
Solution Approach 1:
The first and second photoelectric converters operate continuously and simultaneously during a single exposure period, continuously generating both high-sensitivity and low-sensitivity signals. This eliminates the need for repeated electronic shutter operations, maintaining continuous useful action throughout the frame period. The system achieves wide dynamic range while preserving high operational speed, as both signal types are captured in one continuous exposure rather than requiring multiple sequential operations.
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 enables the acquisition of high-sensitivity and low-sensitivity signals in one frame period, reducing image quality deterioration and enhancing operational speed while maintaining a wide dynamic range.
Implementation Method 1
a first photoelectric converter that generates a first electrical signal
Data Source
AI summary
An imaging device includes a pixel cell including: a first photoelectric converter that generates a first electrical signal; and a first signal detection circuit that detects the first electrical signal. The first signal detection circuit includes: a first transistor one of a source and a drain of which is electrically connected to the first photoelectric converter; a first capacitor having first and second ends, the first end being electrically connected to the other of the source and the drain of the first transistor, a reference voltage being applied to the second end; and a second transistor having a gate electrically connected to the first photoelectric converter. The pixel cell outputs, in one frame period, a first image signal and a second image signal in sequence, the first image signal being output when the first transistor is off, the second image signal being output when the first transistor is on.