Flat Panel Imager Refresh Using Multi-Pulse Segmentation
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Solution Overview
Problem
Conventional refresh operations for flat panel radiation imagers require extended ON times for TFTs, leading to increased power consumption and charge induction issues, resulting in inefficient charge release and unnatural video output.
Innovation Solution
A method involving a multi-pulse pattern for control signals applied to gate lines during the refresh operation, where adjacent switching elements on the same signal line are not turned ON simultaneously, allowing for efficient charge release with reduced power consumption and shorter refresh times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the ON time for TFT is extended to read sufficient charge, then charge reading completeness is improved, but the charge accumulation time for X-ray signals is shortened, reducing output power
Solution Approach 1:
The refresh operation is divided into multiple sequential pulse cycles instead of a single long pulse. Each pulse cycle refreshes a subset of pixels, allowing the TFT to be turned off between pulses. This segmentation enables sufficient charge reading without requiring the TFT to remain ON for the entire refresh period, thus maintaining charge accumulation time for X-ray signals.
Solution Approach 2:
The TFT is turned ON in periodic pulses during the refresh operation rather than continuously. Multiple short pulses are applied sequentially to different gate lines, creating a periodic switching pattern. This allows charge to be read in discrete intervals while the TFT remains OFF during off-periods, preserving the charge accumulation capability.
2Measurement precision
If the ON time for TFT is extended during refresh to release sufficient charge, then charge release completeness is improved, but power consumption increases
Solution Approach 1:
The refresh operation segments the TFT switching into multiple short pulses distributed across different gate lines. Instead of keeping one TFT ON for a long duration to release all charge, the system applies multiple shorter pulses to different pixels sequentially. This reduces the total ON-time and thus power consumption while maintaining complete charge release through the cumulative effect of multiple pulses.
Solution Approach 2:
The TFT switching during refresh is made periodic with multiple short pulses rather than a single long pulse. Each pulse activates a different subset of pixels, creating a distributed time profile of switching. This periodic action reduces the duty cycle and total energy consumption while ensuring complete charge release through repeated pulsing.
3Speed
If adjacent TFTs are turned ON simultaneously during refresh, then refresh speed is improved, but charge induction between adjacent pixels occurs, causing unnatural video output
Solution Approach 1:
The refresh operation segments the activation of adjacent TFTs into non-overlapping time intervals. By assigning different pulse timing to adjacent gate lines, the system ensures that no two adjacent TFTs are ON simultaneously. This temporal segmentation prevents charge induction between adjacent pixels while maintaining efficient refresh speed through parallel processing of non-adjacent pixels.
Solution Approach 2:
The timing control introduces asymmetry in the switching pattern of adjacent TFTs. Instead of symmetric simultaneous activation, the system applies asymmetric timing where adjacent gate lines are activated at different times within the pulse cycle. This asymmetric timing prevents the harmful charge induction effect while preserving the overall refresh functionality.
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 enables efficient release of accumulated electric charge with low power consumption and short refresh periods, stabilizing image output without induced charge effects from adjacent pixels.
Implementation Method 1
a pixel 80 that includes a photoelectric conversion element 11 and a TFT 12, which serves as a switching element
Implementation Method 2
a fluorescent layer in the FPI converts the X-rays that have passed through the human body into visible light
Data Source
Figure 1(a)~1(b)
Figure 2~3
Figure 4~5
AI summary
To provide a method of refresh operation for a flat panel radiation imager that makes it possible to carry out a refresh operation in such a way that electric charge that is accumulated in pixels by photoelectric conversion is efficiently released with low power consumption and during a short period of time. Control signals of the refresh operation are turned into a plurality of successive pulses at regular intervals; and timing is adjusted in such a way that adjacent switching elements disposed on the same signal line are not turned ON at the same timing.