Imaging Sensor Pixel Group Control for Wider Dynamic Range
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Solution Overview
Problem
Conventional imaging units have a limited dynamic range due to low amplification ratios in strong light conditions, leading to weak signals in bright areas and saturation in dark areas, restricting their ability to capture images with a wide range of brightness effectively.
Innovation Solution
The imaging unit employs a dual-group pixel arrangement where one group performs single charge accumulation while another group repeats charge accumulation multiple times, allowing for differential signal processing and output, thereby expanding the dynamic range by adjusting charge accumulation times based on brightness regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single charge accumulation is performed in all pixel groups, then the imaging process is simple and fast, but the dynamic range is limited and signals from weak light regions are insufficient
Solution Approach 1:
The pixel array is divided into multiple pixel groups (first pixel group and second pixel group), where each group performs a different number of charge accumulations. This segmentation allows simultaneous optimization for both weak light regions (multiple accumulations) and strong light regions (single accumulation), resolving the contradiction between signal strength and processing complexity.
Solution Approach 2:
The imaging unit dynamically adjusts the number of charge accumulations based on the incident light intensity detected in each pixel group. Regions with weak incident light perform multiple charge accumulations to amplify signals, while regions with strong incident light perform single accumulation to prevent saturation, thereby expanding the dynamic range without excessive complexity.
2Measurement precision
If multiple charge accumulations are performed to enhance weak light signals, then the dynamic range expands, but the imaging time increases and productivity decreases
Solution Approach 1:
By segmenting the pixel array into groups with different accumulation counts, the system performs multiple accumulations only where necessary (weak light regions) rather than uniformly across all pixels. This selective approach expands the dynamic range while minimizing the impact on overall imaging speed.
Solution Approach 2:
Different regions of the image sensor apply different charge accumulation strategies based on local light conditions. Weak light regions receive multiple accumulations for enhanced signal detection, while strong light regions use single accumulation for rapid capture, thereby optimizing both dynamic range and imaging speed locally across different areas.
3Ease of operation
If uniform charge accumulation is applied across all regions, then the imaging process is straightforward, but signals from both strong and weak light regions cannot be simultaneously optimized
Solution Approach 1:
The pixel array is segmented into multiple pixel groups that can be independently controlled. This segmentation enables different charge accumulation strategies to be applied to different groups based on incident light intensity, allowing simultaneous optimization of signals from both strong and weak light regions while managing complexity through structured group control.
Solution Approach 2:
The imaging unit changes the charge accumulation parameter (number of accumulations) based on the incident light intensity detected in each pixel group. This parameter adaptation allows the system to optimize signal quality across varying light conditions without requiring fundamentally different hardware configurations.
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 enhances the imaging unit's dynamic range, preventing underexposure in shadows and overexposure in highlights, enabling the capture of images with a broader range of brightness without signal saturation.
Implementation Method 1
an imaging element including a photodiode that accumulates electrical charge
Data Source
AI summary
When the amplification ratio is low and strong incident light causes a large charge, the signal retrieved from regions where the incident light is weak is also weak, but when the amplification ratio is high in regions where the incident light is weak, the signal retrieved from regions where the incident light is strong becomes saturated. Therefore, the dynamic range of the imaging unit is narrow. Provided is an imaging unit comprising an imaging section that includes a first group having one or more pixels and a second group having one or more pixels different from those of the first group; and a control section that, while a single charge accumulation is performed in the first group, causes pixel signals to be output by performing charge accumulation in the second group a number of times differing from a number of times charge accumulation is performed in the first group.