TFT Driving Circuit Non-Conducting Voltage Stability

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Solution Overview

Problem

Conventional radiation detection apparatuses face challenges in maintaining a stable non-conducting voltage for extended periods, leading to potential floating circuits and decreased signal-to-noise ratios due to channel leakage in thin-film transistors, which affects the accuracy of radiation detection.

Innovation Solution

The apparatus incorporates a driving circuit formed on a substrate using a TFT process, featuring additional thin-film transistors and capacitors that ensure the non-conducting voltage remains stable by continuing to supply VSS to the driving wires through a control signal, even when the fourth thin-film transistor becomes non-conductive, thus preventing circuit floating and maintaining signal integrity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If additional thin-film transistors and capacitors are added to maintain stable non-conducting voltage, then circuit stability is improved, but device complexity increases

Engineering Contradiction:
Improvecircuit stabilityVSAvoidnumber of transistors and capacitors
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The driving circuit is divided into multiple unit circuits, each corresponding to a row of pixels. Each unit circuit contains specific transistors (first through sixth TFTs) and capacitors (first and second capacitors) that are segmented to perform distinct functions: some transistors control signal transmission while others maintain voltage stability. This segmentation allows the complex circuit to be organized into manageable functional blocks that can be independently analyzed and optimized.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The circuit performs preliminary actions by proactively maintaining the non-conducting voltage at VSS level through the sixth transistor and second capacitor before any floating issue can occur. The control signal continuously activates the sixth transistor to supply VSS to the fourth transistor's gate, preventing the transistor from turning off unintentionally. This preliminary voltage stabilization prevents circuit floating and maintains signal integrity throughout extended periods of operation.

Inventive Principle:
Principle #10Preliminary action

2Measurement precision

If the pixel array pitch is reduced to 50-80 μm, then detection precision is improved, but mounting difficulty increases due to substrate size constraints

Engineering Contradiction:
Improvepixel pitchVSAvoidmounting difficulty
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The substrate serves multiple functions: it acts as both the base for the pixel array and as the integration platform for the driving circuit. The driving circuit is formed directly on the same substrate as the pixel array using TFT processes, eliminating the need for separate mounting of driving circuits. This multi-functional substrate design allows small-pitch pixel arrays (50-80 μm) to be manufactured without the mounting difficulties that would arise from separate circuit board integration.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentEP2549299B1Radiation detection apparatus and detection system including same
Publication Date: 2019.10.30 CANON KK
  • EP2549299B1 patent drawingFigure 1A~1B
  • EP2549299B1 patent drawingFigure 2
  • EP2549299B1 patent drawingFigure 3A~3B

AI summary

A detection apparatus (100) includes a driving circuit unit (120) in which a plurality of unit circuits (121) each including a first circuit that supplies conducting voltage of a switch element (112) of a pixel (110) based on voltage included in a clock signal to a driving wire (160) in accordance with an initiation signal and a second circuit that supplies non-conducting voltage of the switch element to the driving wire in accordance with a termination signal are provided for the plurality of corresponding driving wires and a control unit (150) that supplies the clock signal to the driving circuit unit. The control unit supplies control voltage to the plurality of unit circuits, and each of the plurality of unit circuits further includes a third circuit that continues to supply the non-conducting voltage to the corresponding driving wire in accordance with the control voltage.