Photodetector Pixel Time Waveform Encoding for Single Output Terminal
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Solution Overview
Problem
Photodetectors with multiple pixels and a single output terminal cannot determine which pixel has detected light, limiting their ability to provide precise information in applications like PET apparatuses.
Innovation Solution
The photodetection device employs avalanche photodiodes operating in Geiger mode and quenching resistors, allowing each pixel to output detection signals with unique time waveforms, enabling identification of the detecting pixel based on the time waveform analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If multiple photodetection pixels share a single output terminal, then device complexity is reduced and manufacturing is simplified, but the ability to determine which pixel detected light is lost
Solution Approach 1:
The patent applies parameter changes by assigning different time waveform characteristics (different time constants) to each photodetection pixel's output signal. This allows the system to encode pixel identification information in the temporal domain rather than requiring separate spatial output terminals. Each pixel's detection signal has a unique time waveform parameter that identifies its origin while sharing the common output terminal.
2Measurement precision
If each photodetection pixel has its own output terminal, then pixel identification is straightforward, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent merges multiple pixel output signals into a single common output terminal while maintaining the ability to distinguish individual pixel detections. Instead of having separate output terminals for each pixel, the invention combines all pixel signals through one terminal and uses time waveform analysis to identify the source pixel, thereby simplifying the device structure while preserving measurement precision.
Solution Approach 2:
The patent introduces time waveform characteristics as an intermediary mechanism to carry pixel identification information. Rather than directly routing each pixel's signal to a separate terminal, the time waveform acts as a mediator that encodes the pixel identity within the shared output signal, allowing identification without requiring separate physical output paths.
3Ease of manufacture
If all photodetection pixels use identical circuit configurations, then manufacturing is simplified, but the ability to distinguish between pixels is lost
Solution Approach 1:
The patent applies local quality by introducing a specific parameter variation (different time constants) in the quenching resistors of each photodetection pixel while maintaining overall circuit uniformity. This localized differentiation allows each pixel to have a unique time waveform characteristic for identification, while the rest of the circuit configuration remains standardized for ease of manufacture.
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 determination of the detecting pixel, improving spatial resolution and enabling precise light measurement by distinguishing between pixels through their distinct time waveforms.
Implementation Method 1
each photodetection pixel is constituted by an avalanche photodiode operating in Geiger mode
Implementation Method 2
a quenching resistor connected in series to the avalanche photodiode
Data Source
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AI summary
A photodetector 50 includes N photodetection pixels 52 arranged one-dimensionally or two-dimensionally and each for generating a detection signal in response to incidence of light, and a single output terminal 16 for outputting the detection signal S0 generated in each of the N photodetection pixels 52. Each of the N photodetection pixels 52 includes an avalanche photodiode 53 operating in Geiger mode, and a quenching resistor 54 connected in series to the avalanche photodiode 53, and the N photodetection pixels 52 are configured to output detection signals S0 having time waveforms different from each other. Thus, with a configuration including a plurality of photodetection pixels and a single output terminal, it is possible to realize a photodetector and a photodetection device capable of appropriately determining a pixel detecting light.