Radiation Counting Device Using Segmented AD Conversion
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Solution Overview
Problem
Current radiation counting devices face challenges in accurately performing radiation counting due to noise from transistors in the pixel circuit, leading to errors in digital signals, especially when using AD conversion circuits that convert output voltage from a single photon as a quantization unit.
Innovation Solution
A radiation counting device is designed with a scintillator that generates photons, a pixel circuit to convert photons into charge and generate an analog voltage, and an analog-to-digital conversion circuit that converts the analog voltage into a digital signal in a quantization unit less than the voltage generated from one photon, thereby reducing noise and improving accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the AD conversion circuit uses the output voltage from a single photon as a quantization unit, then the device complexity is reduced, but the measurement precision deteriorates due to noise from transistors in the pixel circuit
Solution Approach 1:
The patent divides the pixel array into multiple independently operable blocks, each with its own AD conversion circuit. This segmentation allows the system to process signals from multiple pixels simultaneously while maintaining low complexity in each individual conversion circuit, thereby improving measurement precision without significantly increasing overall device complexity.
Solution Approach 2:
The patent uses a quantization unit smaller than the full analog voltage from one photon (e.g., half or quarter of the voltage). This excessive precision in quantization helps overcome transistor noise by ensuring that even small signal variations due to noise do not cause incorrect digital output values, thereby improving radiation counting accuracy.
2Measurement precision
If the quantization unit is reduced to half or quarter of the voltage from one photon, then the measurement precision improves, but the device complexity increases due to more complex AD conversion requirements
Solution Approach 1:
By dividing the pixel array into multiple blocks with separate AD conversion circuits, the patent distributes the complex quantization task across multiple simpler circuits. Each circuit handles fewer pixels but maintains high precision quantization, achieving overall high measurement precision without requiring a single overly complex AD conversion circuit.
Solution Approach 2:
The patent employs multiple identical or similar AD conversion circuits, each capable of performing the precise quantization function. Instead of designing one highly complex circuit, the system uses multiple copies of a standardized, moderately complex circuit, simplifying design and manufacturing while maintaining high precision through parallel operation.
3Productivity
If multiple pixel circuits are used to increase detection capability, then the productivity improves, but the object-generated harmful factors worsen due to increased noise from additional transistors
Solution Approach 1:
The patent divides the large pixel array into multiple smaller blocks, each processed by its own AD conversion circuit. This segmentation isolates noise within each block, preventing noise from accumulating across the entire array. The system achieves high detection capability through parallel processing of multiple blocks while limiting the noise impact in each individual circuit.
Solution Approach 2:
By using a quantization unit smaller than the full photon voltage (excessive precision), the patent creates a larger margin between the signal level and the noise level. This allows multiple pixel circuits to operate simultaneously with their inherent transistor noise while still achieving accurate radiation counting, as the reduced quantization unit provides headroom to overcome the cumulative noise effect.
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 allows for accurate radiation counting by minimizing noise and error, enabling precise conversion of analog voltage to digital signals in smaller quantization units, such as half or a quarter of the voltage from one photon, thus enhancing the detection precision.
Implementation Method 1
a scintillator configured to generate a photon when a radiation is incident
Implementation Method 2
a pixel circuit configured to convert the photon into charge, store the charge over a predetermined period, and generate an analog voltage in accordance with amount of the stored charge
Data Source
AI summary
A radiation counting device is provided that includes a scintillator, a pixel circuit, and an analog-to-digital conversion circuit. In the radiation counting device, the scintillator generates a photon when radiation is incident. In the radiation counting device, the pixel circuit converts the photon into charge, stores the charge over a predetermined period, and generates an analog voltage in accordance with the amount of stored charge. In the radiation counting device, the analog-to-digital conversion circuit converts the analog voltage into a digital signal in a predetermined quantization unit less than the analog voltage generated from the one photon.