Dual-TFT X-Ray Detection Panel for Low-Noise High Sensitivity
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Solution Overview
Problem
Existing X-ray detection panels suffer from low sensitivity, image lag, and ghost images due to parasitic capacitance components, with traditional methods to enhance sensitivity causing increased noise or reduced resolution.
Innovation Solution
The X-ray detection panel incorporates a series connection of two readout thin-film transistors and capacitors to enhance output current, along with a reset thin-film transistor to eliminate parasitic capacitance and noise components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If amplification of digital gain of hardware is used to enhance image sensitivity, then image brightness is improved, but image noise increases
Solution Approach 1:
The readout path is segmented into two series-connected thin-film transistor stages. The first TFT transfers charge from the photodiode to an intermediate node, while the second TFT transfers charge from the intermediate node to the readout circuit. This segmentation allows each stage to operate optimally, achieving current amplification without the noise penalties of conventional digital gain amplification.
Solution Approach 2:
The invention changes the operational parameters by using dual TFT stages with optimized gate voltages and threshold characteristics. By carefully selecting the threshold voltages and operating points of the two TFTs, the system achieves effective current amplification (doubling the output current) while maintaining low noise through proper parameter matching and optimization.
2Measurement precision
If software-based image processing is used to enhance image brightness, then image sensitivity is improved, but resolution decreases and additional image processing time is required
Solution Approach 1:
The invention replaces software-based image processing with a hardware-level electrical solution. Instead of using software algorithms to enhance brightness after image acquisition, the system uses a dual TFT readout circuit that amplifies the signal current at the hardware level, achieving sensitivity enhancement without compromising resolution or requiring additional processing time.
3Productivity
If high frames per second is achieved during high-speed dynamic X-ray image acquisition, then acquisition speed is improved, but sensitivity (brightness) of resulting image reduces
Solution Approach 1:
The dual TFT configuration enables continuous efficient charge transfer at high speeds. The first TFT continuously transfers charge from the photodiode to the intermediate node, and the second TFT continuously transfers charge from the intermediate node to the readout circuit. This continuous operation maintains high frames per second while the series connection ensures sufficient current levels for high sensitivity, resolving the trade-off between speed and sensitivity.
4Measurement precision
If traditional single readout thin-film transistor configuration is used, then device complexity is low, but output current is insufficient resulting in low image brightness
Solution Approach 1:
The readout circuit is segmented into two TFT stages connected in series. The first TFT handles charge transfer from the photodiode, and the second TFT handles charge transfer to the readout circuit. This segmentation doubles the effective output current and image brightness while adding only moderate complexity through the introduction of one additional TFT and associated gate control circuitry.
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 doubles the output current, enhances sensitivity without increasing noise or reducing resolution, and effectively prevents image lag and ghost images.
Implementation Method 1
The X-ray detection panel utilizes a photodiode to detect visible light emitted from a scintillator
Implementation Method 2
When irradiated with X-rays, a scintillator is excited by the X-rays and emits visible light
Data Source
AI summary
Disclosed are an X-ray detection panel, an X-ray detector including the same, and a unit pixel for the same. The X-ray detection panel includes a plurality of unit pixels each including a photodiode, a first readout thin-film transistor, and a second readout thin-film transistor, wherein the first and second readout thin-film transistors are electrically connected to the photodiode and are connected in series to each other.