Image Pickup System Pixel Row Charge Accumulation Noise Control
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Solution Overview
Problem
Existing image pickup systems face challenges in managing charge accumulation periods across different pixel rows, leading to noise issues due to charge leakage when pixels in image pickup and function pixel rows commonly use a floating diffusion, particularly in high luminance conditions or excessive light exposure.
Innovation Solution
The system employs a scanning circuit to control charge accumulation periods such that some pixel rows have overlapping periods, while others do not, allowing for partial sharing of a floating diffusion, and the signal processing unit omits signals from pixel rows that commonly use the floating diffusion to minimize noise influence, using signals from other rows for image formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If pixels in image pickup pixel rows and function pixel rows commonly use a floating diffusion, then device complexity is reduced, but noise is generated due to charge leakage
Solution Approach 1:
The pixel array is segmented into multiple pixel rows with different charge accumulation period configurations. Specifically, some pixel rows (first pixel rows) have charge accumulation periods that do not overlap, while other pixel rows (second pixel rows) have overlapping charge accumulation periods. This segmentation allows the system to reduce noise from charge leakage in the first pixel rows while maintaining the simplified floating diffusion structure across all pixels.
2Productivity
If charge accumulation periods of all pixel rows are overlapped, then productivity is improved through parallel processing, but charge leakage noise increases
Solution Approach 1:
Different charge accumulation period configurations are applied to different local regions (pixel rows) of the pixel array. The first pixel rows use non-overlapping charge accumulation periods to minimize charge leakage noise, while the second pixel rows use overlapping charge accumulation periods to maximize productivity. This local differentiation allows the system to optimize both noise performance and efficiency in different regions.
3Measurement precision
If signals from all pixel rows are used for image formation, then measurement precision is improved, but image quality deteriorates due to noise from floating diffusion
Solution Approach 1:
The signal processing unit extracts and uses only the signals from the first pixel rows for image formation, while discarding signals from the second pixel rows that are prone to noise. This extraction of the useful signal component (from first pixel rows) while eliminating the noisy component (from second pixel rows) maintains measurement precision while improving image quality.
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 effectively suppresses noise caused by charge leakage, enabling clear image formation without relying on signals from pixel rows prone to noise due to floating diffusion usage, thereby improving image quality.
Implementation Method 1
a pixel portion where pixels that each includes a photoelectric conversion unit
Data Source
AI summary
In an image pickup system according to an aspect of the present invention, a pixel portion includes a plurality of first pixel rows controlled by a scanning circuit such that charge accumulation periods are at least partially overlapped with each other and a plurality of second pixel rows controlled by the scanning circuit such that charge accumulation periods are not overlapped with the charge accumulation periods of the first pixel rows, part of the plurality of first pixel rows commonly uses a floating diffusion with a pixel in the second pixel row, another part of the plurality of first pixel rows does not commonly use the floating diffusion with the pixel in the second pixel row, and the signal processing unit performs signal processing without using a signal of the pixel in the first pixel row that commonly uses the floating diffusion with the pixel in the second row.