Imaging Unit Charge Accumulation Control for Wider Dynamic Range
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional imaging units have a limited dynamic range due to low amplification ratios in areas with strong incident light, leading to weak signals in low-light regions and signal saturation in high-light regions, restricting the imaging capability to a narrow range.
Innovation Solution
An imaging unit comprising two groups of pixels with different charge accumulation times, allowing for varied charge accumulation and output processes to optimize signal retrieval across different light conditions, thereby expanding the dynamic range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single charge accumulation is performed in all pixel groups, then the device complexity is low and operation is simple, but the dynamic range is limited and cannot capture both weak and strong light signals simultaneously
Solution Approach 1:
The imaging device divides pixels into multiple pixel groups (first pixel group and second pixel group) that can perform charge accumulation independently with different accumulation times. This segmentation allows simultaneous capture of weak light signals (with longer accumulation) and strong light signals (with shorter accumulation), thereby expanding the dynamic range without requiring complex per-pixel control mechanisms
Solution Approach 2:
The patent implements dynamic charge accumulation control where the accumulation time is adjusted based on the incident light intensity for different pixel groups. The control section dynamically assigns longer accumulation times to regions with weak incident light and shorter accumulation times to regions with strong incident light, enabling adaptive optimization of signal retrieval across varying light conditions
2Measurement precision
If the amplification ratio is increased to retrieve weak signals from low-light regions, then the signal quality in dark regions improves, but the signals from high-light regions become saturated
Solution Approach 1:
The patent applies different charge accumulation strategies to different spatial regions based on their local light conditions. Pixels in low-light regions perform multiple charge accumulations with longer integration times to enhance weak signals, while pixels in high-light regions perform fewer accumulations with shorter integration times to prevent saturation. This local differentiation of accumulation parameters optimizes signal retrieval accuracy across the entire imaging field without causing harmful saturation effects
3Adaptability or versatility
If the amplification ratio is decreased to prevent saturation in high-light regions, then the dynamic range extends to bright areas, but the signals from low-light regions become too weak to retrieve
Solution Approach 1:
By segmenting the pixel array into multiple groups with independent charge accumulation control, the patent enables different accumulation durations for different regions. This segmentation allows the system to simultaneously maintain high signal retrieval accuracy in low-light regions (through longer accumulation) and prevent saturation in high-light regions (through shorter accumulation), thereby achieving both goals without compromise
Solution Approach 2:
The patent changes the charge accumulation parameter (accumulation time and number of accumulations) based on the incident light intensity for each pixel group. The control section adjusts these parameters dynamically, assigning longer accumulation times to dark regions to enhance weak signals and shorter accumulation times to bright regions to prevent saturation, thus optimizing both signal retrieval accuracy and dynamic range coverage
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 by allowing for multiple charge accumulations in high-light regions and single accumulations in low-light regions, resulting in improved signal quality and reduced saturation, enabling the capture of images with a broader range of brightness without under or overexposure.
Implementation Method 1
An imaging unit is known in which a back emission type imaging chip and a signal processing chip are connected via micro-bumps provided for each cell containing a group of pixels
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.