Imaging Device Dynamic Integration Period Control
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Solution Overview
Problem
Current imaging devices face challenges in achieving high dynamic range and accurate light level detection across a wide range of light levels without causing significant charge overflow or saturation, which affects the accuracy and reliability of pixel readouts.
Innovation Solution
The implementation of a pixel structure that samples charge levels non-destructively before each integration period, using exponential time scaling for integration periods and correlated double sampling for charge overflow detection, allows for accurate light level indication by initiating shorter integration periods when charge overflow is detected, minimizing the impact on ongoing integration and reducing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed integration period is used for all pixels, then the device complexity is reduced, but the measurement precision of light levels across different brightness conditions deteriorates
Solution Approach 1:
The patent implements dynamic integration periods by monitoring charge levels during integration and adjusting the integration time for each pixel based on its current charge state. Pixels approaching saturation automatically trigger a shorter integration period, while others continue with the current period. This dynamic adjustment maintains high measurement precision across varying light levels without requiring complex pre-programmed integration schedules for each pixel.
Solution Approach 2:
The system continuously monitors the charge level in each pixel during the integration period and uses this feedback to determine whether to extend or terminate the integration. When charge approaches a threshold level, the system feedback-controlledly reduces the integration period for that specific pixel. This feedback mechanism enables adaptive integration time control that optimizes measurement precision while avoiding the complexity of predetermined multi-period schemes.
2Measurement precision
If the integration period is extended to capture more light, then the measurement precision for low light levels improves, but charge overflow and saturation increase
Solution Approach 1:
The patent performs preliminary non-destructive sampling of pixel charge levels at multiple points during the integration period. By checking charge levels before the integration completes, the system can predict which pixels are at risk of saturation and adjust their integration periods accordingly. This preliminary action prevents charge overflow while maintaining extended integration benefits for pixels that remain within safe charge limits.
Solution Approach 2:
The system applies different integration period extensions to different pixels based on their individual charge states rather than using a uniform approach. Pixels with low charge levels can benefit from extended integration to improve low-light detection, while pixels approaching saturation automatically receive shorter integration periods. This localized quality control allows each pixel to operate at optimal precision without causing overflow, resolving the contradiction between extended integration benefits and overflow risks.
3Reliability
If multiple reads are performed during integration to monitor charge levels, then the reliability of overflow detection improves, but the loss of time for read operations increases
Solution Approach 1:
The patent extracts only the necessary charge level information from pixels during integration using non-destructive sampling methods. Instead of performing full readout operations that would interrupt integration and cause time loss, the system extracts minimal charge level data sufficient to determine whether pixels are approaching saturation. This selective extraction maintains high overflow detection reliability while minimizing the time penalty associated with multiple reads.
Solution Approach 2:
The system performs partial reads that provide sufficient information for overflow detection without completing full readout sequences. By performing just enough sampling to detect charge levels and predict saturation risk, the system achieves high reliability in overflow detection without the time cost of multiple complete reads. The sampling frequency and depth are optimized to provide adequate detection capability with minimal time loss.
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 enables consistently high accuracy in light level detection across a wide range of light levels, minimizing charge overflow errors and maintaining the integrity of pixel readouts, thus enhancing the dynamic range and reliability of imaging devices.
Implementation Method 1
an array of photo-detectors that generate electrons
Data Source
Figure 1~5
Figure 6
AI summary
The present invention relates to improved imaging devices having high dynamic range and to monitoring and automatic control systems incorporating the improved imaging devices.