Image Sensor Pixels with Variable Integration Periods
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Solution Overview
Problem
Image sensors face challenges in capturing high dynamic range images due to limited dynamic range, resulting in motion artifacts and increased noise when varying integration periods, which affects image quality.
Innovation Solution
An image sensor system with a first portion of pixels accumulating charge during a first integration period and a second portion accumulating charge during multiple shorter integration periods within the first period, with readout circuitry and processor management to combine charges and reduce artifacts and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pixels have different integration periods to improve dynamic range, then image detail in both bright and dark areas is improved, but motion artifacts occur due to scene changes between capture times
Solution Approach 1:
The pixel array is segmented into first pixels with longer integration periods and second pixels with shorter integration periods. This segmentation allows different regions to capture light for different durations, enabling the system to capture both bright and dark areas with appropriate exposure times while reducing motion artifacts through selective combination of their respective signals.
2Measurement precision
If pixels have different integration periods to improve dynamic range, then high light and low dark areas are captured better, but noise increases in the final image
Solution Approach 1:
The signals from first pixels (longer integration period) and second pixels (shorter integration period) are merged to produce the final image. This combining approach allows the system to leverage the high signal quality from longer integration for dark areas while using shorter integration signals for bright areas, thereby achieving improved dynamic range while managing noise levels through selective signal integration.
3Measurement precision
If multiple images are captured with different integration periods, then high dynamic range image is produced, but time consumption increases
Solution Approach 1:
The first pixels and second pixels operate simultaneously and continuously during the same overall time period, with each pixel type accumulating charge for its designated integration period without requiring sequential capture. This parallel operation eliminates the need for multiple separate capture passes, thereby achieving high dynamic range imaging without proportionally increasing total capture time.
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 image quality by reducing motion artifacts and noise, improving the dynamic range and signal-to-noise ratio, while also optimizing power consumption and enabling higher frame rates.
Implementation Method 1
a first portion of the pixels accumulate charge during a first integration period and a second portion of the pixels accumulate charge for a shorter second integration period
Data Source
AI summary
An image sensor includes pixels that accumulate charge during a first integration period and pixels that accumulate charge during shorter second integration periods when an image is captured. The pixels having the shorter second integration period accumulate charge at two or more different times during the first integration period. Charge is read out of the pixels associated with the first integration period at the end of the first integration period, while charge is read out of the pixels having the second integration period at the end of each second integration period.