Grouped Pixel Array for High Temporal Resolution CMOS Sensors
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Solution Overview
Problem
CMOS image sensors used for detecting weak light and scintillation light generated by radiation face challenges in achieving high temporal resolution due to limitations in frame rate and photon counting efficiency.
Innovation Solution
An image-capturing device with a pixel array unit divided into groups, where all pixels in a group are driven simultaneously, and a control unit manages the exposure and read-out periods to ensure consistent timing across all groups, enhancing temporal resolution and binary determination of photon incidence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the frame rate is increased to improve temporal resolution for photon counting, then the temporal resolution is improved, but the device complexity and power consumption increase
Solution Approach 1:
The pixel array is divided into multiple groups, with each group driven at the same timing but different from other groups. This segmentation allows the system to achieve high temporal resolution through coordinated group operations rather than requiring every pixel to operate independently at maximum frame rates, thereby reducing overall device complexity while maintaining measurement precision.
Solution Approach 2:
The control unit implements periodic driving patterns where pixels in the same group are driven at regular intervals. By organizing pixels into groups with synchronized periodic driving, the system achieves consistent temporal resolution across all pixels without requiring continuous high-speed operation of the entire array, thus managing device complexity while improving temporal resolution measurement.
2Measurement precision
If the frame rate is increased to improve temporal resolution for photon counting, then the temporal resolution is improved, but the power consumption increases
Solution Approach 1:
By segmenting the pixel array into multiple groups that can be driven independently at optimized intervals, the system reduces overall power consumption compared to driving all pixels continuously at maximum frame rate. Each group can be activated only when needed for photon counting, reducing energy waste while maintaining the required temporal resolution for accurate radiation detection.
Solution Approach 2:
The periodic driving scheme allows pixels to remain in a low-power state between activation cycles. By implementing regular, predictable driving patterns for pixel groups, the system can optimize power management while ensuring temporal resolution requirements are met during active measurement periods, thereby reducing overall power consumption while improving temporal resolution capability.
3Quantity of substance
If photons from multiple gamma rays incident in the same exposure time are detected, then the detection capability is improved, but the measurement precision of individual photon events deteriorates
Solution Approach 1:
Dividing the pixel array into multiple groups with different driving timings allows the system to separate photons from different gamma rays into different exposure windows. This segmentation prevents photon pile-up by ensuring that photons from multiple gamma rays do not incident in the same exposure time, thereby maintaining measurement precision while still detecting a sufficient quantity of photons across all groups.
Solution Approach 2:
By implementing periodic driving patterns with appropriate timing intervals between different pixel groups, the system creates distinct measurement windows that prevent overlapping photon events. This periodic operation ensures that photons from multiple gamma rays are detected in separate exposure periods, maintaining temporal resolution and measurement precision while accumulating sufficient photon statistics across multiple periods.
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 significantly improves temporal resolution, allowing for more accurate detection of radiation energy and incidence events, while maintaining cost-effectiveness by using CMOS sensors instead of photomultipliers.
Implementation Method 1
a pixel array unit including a plurality of pixels classified into two or more groups
Implementation Method 2
detect scintillation light generated by incidence of radiation upon a scintillator
Data Source
AI summary
To improve a temporal resolution.An image-capturing device includes a pixel array unit and a control unit. The pixel array unit includes a plurality of pixels classified into two or more groups, wherein pixels which belong to a same group are driven at a same timing. The control unit controls driving of the pixel array unit so that a number of groups in a period of time of read-out of electrical charge is a same number in any given timing in image-capturing operation, and that a number of groups in a period of time of exposure and accumulation of electrical charge is a same number in any given timing in the image-capturing operation.