X-ray Sensor Processing Circuit Non-linearity Compensation
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Solution Overview
Problem
X-ray devices face challenges in maintaining image quality due to non-linear transfer functions and temperature-dependent structural noises, which affect pixel voltages and charges, leading to gain differences and artifacts in reconstructed images, especially in three-dimensional applications.
Innovation Solution
A processing circuit for X-ray sensors is introduced, featuring an amplifier with a feedback loop that includes a transfer function identical to that of the sensor pixels, allowing for compensation of structural noises and non-linearity by matching the transfer function of the feedback loop with the pixel circuits, thereby reducing noise and maintaining image processing speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the transfer function of the sensor pixels is non-linear and temperature-dependent, then the sensor can operate across varying temperatures, but structural noises and gain differences occur leading to image quality degradation
Solution Approach 1:
The patent implements a feedback loop in the processing circuit that feeds back a portion of the output signal to the input. This feedback mechanism allows the system to automatically compensate for non-linearities and temperature-dependent variations in the sensor pixels by comparing the actual output with the expected output and adjusting accordingly, thereby maintaining image quality across varying temperatures.
Solution Approach 2:
The patent changes the parameters of the processing circuit, specifically designing the transfer function of the processing circuit to match the transfer function of the sensor pixels. By making the transfer functions identical, the system can compensate for non-linearities and temperature-dependent effects, reducing structural noise and maintaining consistent image quality across different operating conditions.
2Reliability
If the transfer function of the processing circuit is made identical to the sensor pixels, then structural noises are compensated, but the circuit complexity increases
Solution Approach 1:
The patent creates a copy of the sensor pixel transfer function in the processing circuit. By designing the processing circuit to have the same transfer function as the sensor pixels, the system can replicate and compensate for non-linearities and temperature-dependent effects. This copying approach allows for effective noise compensation while keeping the implementation relatively straightforward.
3Measurement precision
If gain differences are compensated for non-linear transfer functions, then measurement precision improves, but the processing time increases due to temperature dependency
Solution Approach 1:
The patent implements a continuous feedback mechanism that operates throughout the signal processing pipeline. By maintaining continuous feedback rather than periodic corrections, the system can compensate for gain differences and non-linearities in real-time without requiring additional processing steps, thereby maintaining measurement precision while minimizing processing time loss.
Data Source
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AI summary
A processing circuit for an X-ray sensor for collecting at least a first pixel information of a first pixel and a second pixel information of a second pixel is provided. The processing circuit comprises an amplifier (112), a feedback loop (113) and a first collecting device (111). It is provided a compensation for a non-linearity in the pixels or in the pixel circuits (100, 200) by applying an inverse non-linearity (125) in the periphery of the X-ray sensor. A processing circuit (110) may provide a copy of a pixel voltage and/or of a pixel charge. In the case of pixel charge a non- linear characteristic of a pixel capacitance may be compensated.