X-ray Detector Noise Reduction via Timing-Based Digital Conversion
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Solution Overview
Problem
Conventional X-ray detectors face challenges in accurately discriminating pixel levels due to noise and are prone to noise in post-processing circuits, leading to increased power consumption.
Innovation Solution
An X-ray detector design that includes a pixel unit with a photodiode outputting voltage proportional to X-ray incidence, a comparator converting this voltage to a logic signal, and a counter converting the logic signal's duration into a digital output, eliminating the need for amplifiers and analog-to-digital converters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional photodiode-based X-ray detection with voltage amplification is used, then signal detection capability is maintained, but noise sensitivity increases and power consumption rises
Solution Approach 1:
The patent extracts and eliminates the noisy components (amplifiers and ADCs) from the signal processing chain by directly converting the photodiode voltage signal to a digital domain through a timing-based method, where the X-ray detection result is represented by the duration of a digital pulse rather than an amplified analog voltage
Solution Approach 2:
The patent replaces the conventional electronic amplification and analog-to-digital conversion system with a direct timing-based digital encoding system, where the analog voltage signal is converted to a digital time-duration signal, eliminating the need for noisy analog processing circuits
2Ease of operation
If amplifiers and ADCs are used in post-processing circuits, then signal conversion is achieved, but power consumption increases
Solution Approach 1:
The patent removes the power-intensive amplifier and ADC components from the signal processing chain by implementing a direct voltage-to-time conversion method that outputs digital signals without requiring analog amplification or conventional analog-to-digital conversion
Solution Approach 2:
The patent changes the signal representation parameter from voltage amplitude (requiring amplification) to time duration (directly measurable), fundamentally altering how the X-ray signal is encoded and processed to eliminate power-consuming analog circuits
3Measurement precision
If voltage amplification is used to enhance signal output, then detection sensitivity is maintained, but noise from post-processing circuits increases
Solution Approach 1:
The patent extracts and removes the noise-generating amplifier and ADC circuits from the signal path by implementing a timing-based digital encoding scheme that directly converts photodiode voltage to digital pulse duration, eliminating the source of post-processing circuit noise
Solution Approach 2:
The patent performs the signal-to-digital conversion action preliminarily and directly at the photodiode output stage through timing measurement, before the signal would otherwise require amplification and conventional ADC conversion, preventing noise introduction from subsequent processing stages
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 reduces noise sensitivity and power consumption by converting X-ray signals directly into digital form through time-based processing, enhancing resolution and enabling low-power operation.
Implementation Method 1
a scintillator or a phosphor being located in front of a photodiode may absorb X-rays to radiate visible light corresponding to the absorbed X-rays, the photodiode may convert the visible light into a photocurrent
Implementation Method 2
a scintillator or a phosphor being located in front of a photodiode may absorb X-rays to radiate visible light corresponding to the absorbed X-rays
Data Source
AI summary
The present disclosure relates to an X-ray detector which includes a pixel unit configured to include a photodiode and to output a voltage corresponding to an incident amount of X-rays, a comparator configured to compare the output voltage of the pixel unit with a preset threshold voltage to output a logic signal, and a counter configured to count the output signal of the comparator to convert to a digital output.