Photon Counting Detector Readout Circuit with Sequential Threshold Switching
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Solution Overview
Problem
Current photon counting detectors face challenges in generating high-resolution images due to the size of readout circuits, which need to be reduced to accommodate more pixels, and existing methods fail to effectively distinguish energy bands of photons in multi-energy radiation.
Innovation Solution
The proposed solution involves a photon counting detector with a readout circuit configuration that includes a comparator, signal processor, multiplexer, and counter, which compares electric signals with multiple threshold values to distinguish and count photons in each energy band, allowing for finer division of energy bands and reducing the size of readout circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple discriminators with adjustable thresholds are connected in parallel to distinguish energy bands, then energy band distinction capability is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple discrimination functions into a single discriminator by sequentially switching between different threshold values. Instead of using multiple parallel discriminators, the invention integrates their functionality into one unit through time-sequential operation, thereby reducing device complexity while maintaining energy band distinction capability.
Solution Approach 2:
The patent introduces dynamic threshold switching to enable a single discriminator to perform multiple energy band distinctions. By dynamically changing the threshold value based on the input signal amplitude, the system achieves adaptive energy band separation without requiring multiple fixed-threshold discriminators.
2Area of moving object
If readout circuit size is reduced to accommodate more pixels, then pixel density and image resolution are improved, but circuit functionality may be compromised
Solution Approach 1:
The patent merges multiple readout circuit functions into a single compact circuit by implementing sequential threshold switching. This integration reduces the overall circuit area while maintaining the functionality to distinguish multiple energy bands, thereby accommodating more pixels without compromising circuit capability.
Solution Approach 2:
The patent designs a universal readout circuit that can handle multiple energy band distinctions through a single comparator with dynamically switchable thresholds. This multi-functional approach eliminates the need for multiple specialized circuits, reducing area while preserving comprehensive functionality.
3Measurement precision
If photon counting method is used to generate high quality images with distinguishable energy bands, then image quality is improved, but processing time and complexity increase
Solution Approach 1:
The patent employs periodic threshold switching to sequentially distinguish different energy bands within a single exposure. By periodically alternating between different threshold values, the system captures multiple energy band information simultaneously in one shot, eliminating the need for multiple exposures and reducing processing time.
Solution Approach 2:
The patent maintains continuous photon counting operation while dynamically switching thresholds to distinguish energy bands. This continuous operation ensures that no photons are missed during the discrimination process, maintaining high image quality while efficiently processing all energy bands in a single uninterrupted measurement.
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 enables the generation of high-resolution images by accurately distinguishing and counting photons in each energy band, improving image quality and reducing power consumption by operating at a lower rate.
Implementation Method 1
the comparator compares an amplitude of the accumulated electric signal with a threshold value
Implementation Method 2
The indirect method generates an image via sequential conversions from X-rays to visible light and then from the visible light to an electric signal
Data Source
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Figure 5
AI summary
An apparatus for distinguishing energy band of photon in a readout circuit that counts photons in multi-energy radiation incident onto a sensor (21) for each energy band includes an integrator (41) configured to accumulate an electric signal received from the sensor that has undergone photoelectric conversion from the photon; a comparator (42) configured to compare the accumulated electric signal received from the integrator with one of a plurality of threshold values; and a signal processor (43) configured to instruct sequential switching from one of the plurality of threshold values to another one of the plurality of threshold values according to a result of a comparison received from the comparator; and output digital signal that distinguish an energy band of the photon based on results received from the comparator of sequential comparisons of the accumulated electric signal with the plurality of threshold values.