Radiation Imaging Pixel Array Noise Suppression via Correlated Double Sampling
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Solution Overview
Problem
Existing radiation imaging apparatuses face detection errors due to noise currents from sources like commercial power supplies and physical shocks, which conventional methods, such as subtracting dark current, cannot effectively mitigate, especially for noise frequencies above 1 Hz.
Innovation Solution
The radiation imaging apparatus incorporates a detection circuit that calculates radiation information by processing multiple current signal values through a bias line, using techniques like Correlated Double Sampling to differentiate between radiation-induced currents and noise, thereby reducing detection errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a sample and hold circuit is arranged to hold dark current flowing through the bias line, then detection error from dark current is reduced, but detection error from noise current (especially above 1 Hz) cannot be effectively suppressed
Solution Approach 1:
The patent performs preliminary sampling of the bias line current at multiple time points before radiation exposure to establish a baseline noise profile. By capturing noise characteristics in advance (including high-frequency noise above 1 Hz), the system can later differentiate between pre-existing noise and radiation-induced current, thereby resolving the contradiction between reducing dark current errors and suppressing noise current errors.
Solution Approach 2:
The system continuously monitors the bias line current and compares it against the previously sampled baseline values. By implementing feedback mechanisms that actively compare real-time current measurements with historical noise profiles, the system dynamically identifies radiation events while filtering out noise, thus improving both measurement precision and reliability simultaneously.
2Device complexity
If a threshold comparison method is used to detect radiation, then simple detection is achieved, but false detection occurs when noise current exceeds the threshold
Solution Approach 1:
The patent segments the detection process into multiple independent stages: baseline sampling, noise characterization, real-time monitoring, and threshold comparison. By dividing the detection function into separate modules that each handle specific aspects of the measurement, the system maintains relative simplicity while achieving high accuracy through the coordinated operation of these segmented functions.
Solution Approach 2:
Instead of using a single threshold comparison, the patent performs multiple partial measurements at different time points and uses the aggregate information to make the final detection decision. By taking excessive samples beyond what a single threshold check would provide, the system accumulates sufficient evidence to distinguish radiation from noise with high confidence, thereby maintaining simplicity while improving precision.
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 effectively suppresses detection errors caused by noise currents, improving the accuracy of determining radiation exposure by isolating radiation-induced signals from noise, especially in the presence of commercial power supply and shock-induced noise.
Implementation Method 1
each pixel including a conversion element for accumulating charge in accordance with radiation
Data Source
AI summary
A radiation imaging apparatus includes a pixel array having pixels including conversion elements and switching elements, a bias line for supplying a bias potential to the conversion elements; driving lines for supplying a signal to control the switching elements, a driving unit for performing an initialization operation of supplying a driving signal to each driving line group, switching each driving signal from an OFF voltage to an ON voltage, and then returning the driving signal to the OFF voltage; an acquisition unit configured to acquire a plurality of times in each driving cycle a signal value representing a current flowing through the bias line; a calculation unit configured to calculate radiation information based on the signal values; and a determination unit configured to determine whether irradiation of the pixel array with radiation is present based on the radiation information.