Flat Panel Detector Pixel Circuit Storage Architecture
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Solution Overview
Problem
The storage capacitance in flat panel detectors' pixel units is easily saturated due to manufacturing limitations and device size constraints, affecting the display and signal-to-noise ratio of optical signals converted into electrical signals.
Innovation Solution
A pixel circuit with an M×N array of pixel units and N storage circuits, where each storage circuit has a capacitor and transistors to store and output voltage based on induced current, allowing for controlled storage and readout of charge data, with column-specific storage capacitors outside the pixel array to prevent capacitance limitations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If storage capacitance is increased within pixel units, then more charges can be stored, but device size increases and manufacturing complexity increases
Solution Approach 1:
The patent divides the storage function into two locations: pixel units and column storage circuits. Pixel units perform photoelectric conversion and initial charge storage, while column storage circuits handle bulk charge storage. This segmentation allows the system to achieve large storage capacitance without increasing pixel unit size, as the column storage circuits are located outside the pixel array.
Solution Approach 2:
The patent moves the storage capacitance from the two-dimensional pixel unit plane to the column dimension outside the pixel array. By placing storage circuits in the column direction rather than within each pixel unit, the system achieves large storage capacitance without increasing the area of the pixel array, effectively utilizing spatial dimensionality to resolve the contradiction.
2Quantity of substance
If storage capacitance is increased within pixel units, then more charges can be stored, but manufacturing precision requirements increase
Solution Approach 1:
The patent separates the storage function into pixel units and column storage circuits. This segmentation allows the complex large-capacitance storage to be implemented in column circuits where manufacturing precision requirements are lower, while pixel units maintain simple, precise photoelectric conversion functionality. The column storage circuits can use larger, less precision-critical components.
Solution Approach 2:
The patent extracts the storage capacitance function from the pixel units and places it in column storage circuits. This extraction removes the burden of implementing large storage capacitance within the constrained pixel unit manufacturing process, allowing pixel units to focus on precise photoelectric conversion while column circuits handle the bulk storage with more relaxed manufacturing requirements.
3Area of moving object
If pixel unit size is reduced, then array density increases, but storage capacitance in each pixel unit decreases
Solution Approach 1:
The patent compensates for reduced pixel unit storage capacitance by utilizing the column dimension outside the pixel array. Column storage circuits provide additional storage capacity that scales with the number of columns rather than pixel unit area, allowing pixel units to be miniaturized while the overall system maintains adequate storage capacitance through the extended column storage architecture.
Solution Approach 2:
The patent merges the storage function of pixel units with column storage circuits to create a hybrid storage system. The pixel units provide local charge storage, while column storage circuits provide bulk storage capacity. This combination allows pixel units to be small for high density while the merged column storage system provides the total storage capacitance needed for the imaging application.
4Measurement precision
If more charges are accumulated, then signal sensitivity improves, but storage capacitance saturation occurs faster
Solution Approach 1:
The patent segments the charge accumulation and storage into two stages: pixel units accumulate charges from photoelectric conversion with high sensitivity, then transfer charges to column storage circuits for bulk storage. This segmentation allows the pixel units to operate at full sensitivity without being constrained by small storage capacitance, as the column circuits provide the additional capacity needed to handle large charge volumes.
Solution Approach 2:
The patent introduces column storage circuits as an intermediary between pixel units and the readout system. This intermediary provides a large-capacity buffer that receives charges from sensitive pixel units, allowing pixel units to accumulate maximum charges for high signal sensitivity while the intermediary column storage prevents saturation by providing additional storage capacity.
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 solution enables the readout of larger voltages and reduces the signal-to-noise ratio, improving image quality by overcoming capacitance limitations and enhancing the detection capabilities of flat panel detectors.
Implementation Method 1
a photodiode having a first electrode connected to a reference signal terminal, and a second electrode connected to a gate of the amplification transistor
Data Source
AI summary
The present disclosure discloses a pixel circuit and a method for controlling the same, and a flat panel detector. The pixel circuit includes: a plurality of pixel units arranged in an M×N array, wherein each of the pixel units is configured to sense an optical signal and generate induced current based on the sensed optical signal, where M and N are integers greater than or equal to 1; and N storage circuits connected to N columns of pixel units respectively, wherein each of the storage circuits has an input signal terminal connected to a respective column of pixel units, a control signal terminal and an output signal terminal, and is configured to receive induced current from the respective column of pixel units at the input signal terminal, store a voltage based on the received induced current, and provide the stored voltage at the output signal terminal under control of a signal at the control signal terminal.