Detector Unit Cell Array with Deterioration Monitoring Pixels
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Solution Overview
Problem
Existing radiation detectors suffer from time-related deterioration due to radiation exposure, leading to decreased detection precision, as the incident radiation amount varies between pixels, making it difficult to effectively suppress degradation using conventional methods.
Innovation Solution
The detector incorporates a unit cell array with both effective pixels and deterioration detection pixels, where the latter has a distinct pixel structure with a constant voltage source, allowing for monitoring of threshold voltage changes and adjustment of driving voltages to compensate for deterioration, thereby maintaining detection precision over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If light-shielded pixels are used for correction, then detection precision can be improved initially, but time-related deterioration caused by radiation cannot be effectively suppressed
Solution Approach 1:
The pixel array is segmented into three distinct types: effective pixels for primary detection, deterioration detection pixels for monitoring degradation, and dark current detection pixels for monitoring dark current. This segmentation allows each pixel type to serve its specific function independently, enabling effective tracking and correction of radiation-induced deterioration without compromising detection precision.
Solution Approach 2:
The system implements feedback mechanisms where deterioration detection pixels continuously monitor threshold voltage changes and dark current detection pixels monitor dark current levels. These monitored values are fed back to correction circuits that adjust the detection signals from effective pixels in real-time, compensating for radiation-induced deterioration and maintaining detection precision over extended periods.
2Productivity
If pixels are exposed to radiation for detection, then detection capability is maintained, but time-related deterioration progresses at different speeds across pixels
Solution Approach 1:
Different regions of the pixel array are assigned different functional qualities: effective pixels are optimized for detection sensitivity, while deterioration detection pixels are specifically configured to monitor threshold voltage changes. This local differentiation allows the system to maintain high detection capability in effective pixels while using specially-designed deterioration detection pixels to uniformly track radiation effects across the array.
Solution Approach 2:
Deterioration detection pixels are configured as copies of effective pixels in terms of their exposure to radiation, ensuring they experience the same radiation environment and deterioration patterns. This copying approach allows the system to model and predict deterioration across all pixels by monitoring a representative subset, enabling uniform deterioration tracking while maintaining detection capability.
3Measurement precision
If conventional correction methods are used, then initial detection precision is maintained, but degradation occurs over time due to varying radiation exposure
Solution Approach 1:
The system performs preliminary measurements by dedicating specific pixels to monitor threshold voltage changes and dark current before these deteriorations affect the effective detection pixels. By detecting deterioration trends early through specialized monitoring pixels, the system can apply corrective adjustments in advance, extending the operational lifespan while maintaining detection precision.
Solution Approach 2:
The correction circuits dynamically adjust detection parameters based on real-time measurements from deterioration and dark current detection pixels. When radiation-induced threshold voltage shifts or dark current increases are detected, the system changes correction parameters to compensate, allowing the detector to maintain precision over extended periods and effectively extending its operational lifespan.
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 configuration effectively addresses time-related deterioration by allowing for real-time adjustment of driving voltages, maintaining high detection precision and extending the detector's lifespan by compensating for changes in threshold voltage and dark current levels.
Implementation Method 1
a first conversion element configured to convert an incident energy beam into a signal charge
Data Source
AI summary
A detector includes a unit cell array in which a plurality of unit cells are arranged. The plurality of unit cells include a first unit cell including a first conversion element and a first amplification transistor including a control electrode connected to the first conversion element, the first unit cell being configured to output a signal obtained by amplifying the signal charge by the first amplification transistor, and a second unit cell including a second amplification transistor including a control electrode connected to a constant voltage source, the second amplification transistor being configured to output a signal corresponding to a voltage of the constant voltage source by the second amplification transistor. The first unit cell and the second unit cell are disposed in an irradiated region in the unit cell array, the irradiated region being configured to be irradiated with the energy beam.