Imaging Unit Dynamic Amplification for Wide Dynamic Range
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Solution Overview
Problem
CMOS imaging units face limitations in dynamic range due to fixed amplification factors, leading to weak signal retrieval in bright areas and saturation in dark areas, as the amplification factor cannot be adjusted effectively for varying light conditions.
Innovation Solution
The imaging unit employs a serial amplification amplifier section with multiple feedback capacitors to adjust amplification ratios dynamically, allowing for two amplification ratios to be used in a single exposure, with the first amplification ratio for bright areas and a second for dark areas, enabling the combination of signals to expand the dynamic range without saturation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed amplification factor is used in the amplification circuit, then the circuit structure is simple, but the dynamic range is limited and cannot accommodate both intense and weak incident light
Solution Approach 1:
The patent implements dynamic amplification factor selection by providing multiple feedback capacitors (first feedback capacitor and second feedback capacitor) that can be selectively connected to the amplification circuit. The amplification factor selection circuit dynamically switches between different amplification factors based on the intensity of incident light, allowing the system to adapt to varying light conditions and expand the dynamic range while maintaining manageable circuit complexity through systematic design.
Solution Approach 2:
The patent changes the amplification factor parameter by switching between different feedback capacitor configurations. When intense light is detected, a first amplification factor is used; when weak light is detected, a second amplification factor is used. This parameter change approach allows the amplification circuit to handle a wider range of light intensities, effectively expanding the dynamic range without fundamentally redesigning the circuit architecture.
2Object-affected harmful factors
If the amplification factor is reduced to accommodate intense incident light, then saturation is prevented in bright areas, but the signal from weak light regions becomes too weak
Solution Approach 1:
The patent applies different amplification factors to different spatial regions based on local light intensity conditions. Bright regions are processed with a first amplification factor to prevent saturation, while dark regions are processed with a second amplification factor to maintain sufficient signal strength. This local quality approach allows each region to be optimized according to its specific lighting conditions, resolving the contradiction between handling intense and weak light simultaneously.
Solution Approach 2:
The amplification factor is dynamically adjusted based on the detected light intensity in different regions. The image processing circuit determines whether each pixel region contains intense or weak light and selectively applies the appropriate amplification factor. This dynamic adaptation ensures that bright areas do not saturate while dark areas maintain adequate signal strength, effectively resolving the contradiction.
3Manufacturing precision
If the amplification factor is increased to accommodate weak incident light, then signal strength in dark areas is improved, but bright areas become saturated
Solution Approach 1:
The patent implements local quality processing by applying different amplification factors to different spatial regions. Dark regions receive a second amplification factor to enhance signal strength, while bright regions receive a first amplification factor to prevent saturation. This region-specific processing resolves the contradiction by optimizing amplification for each local condition rather than using a uniform factor across the entire image.
Solution Approach 2:
The system dynamically selects the appropriate amplification factor based on the light intensity characteristics of each region. The image processing circuit continuously monitors light intensity and switches between first and second amplification factors as needed. This dynamic adjustment prevents bright area saturation while maintaining sufficient signal strength in dark areas, effectively resolving the contradiction.
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 allows for an expanded dynamic range in imaging, preventing overexposure in bright areas and underexposure in dark areas, while reducing noise and maintaining signal integrity, effectively addressing the limitations of fixed amplification factors.
Implementation Method 1
a photoelectric converter 101 that converts received light into charge
Implementation Method 2
a floating diffusion 103 that outputs the pixel signal to the vertical signal line 200
Implementation Method 3
a serial amplification amplifier section 300 that amplifies the pixel signal retrieved from the floating diffusion 103
Data Source
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AI summary
There is a demand for increasing the dynamic range of an imaging unit. Provided is an imaging unit comprising a pixel section that outputs a pixel signal corresponding to a reset potential after a reset and a signal potential after charge accumulation; an amplifying section that amplifies the pixel signal with a first amplification ratio or a second amplification ratio that is different from the first amplification ratio; and a control section that causes the amplifying section to amplify the pixel signal corresponding to a change from the reset potential to the signal potential with the first amplification ratio, and then causes the amplifying section to amplify the pixel signal corresponding to a change from the signal potential to the reset potential with the second amplification ratio.