Rectifying Element Stabilizes Signal Current Potential in Display Device
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Solution Overview
Problem
Active matrix display devices face issues with luminance variations due to changes in current characteristics of driving TFTs, leading to inconsistent light emission in self-light emitting displays like OLEDs, and existing solutions struggle to rapidly stabilize signal current potentials during noise events.
Innovation Solution
A semiconductor device configuration incorporating a transistor, current source, capacitor, and rectifying elements to rapidly stabilize signal current potentials by connecting the transistor's drain terminal to a current source and using rectifying elements to manage potential changes, ensuring the potential returns within a normal range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a current write type pixel circuit is used to suppress luminance variations, then luminance uniformity is improved, but the response time to stabilize current increases
Solution Approach 1:
The patent applies preliminary action by pre-charging the capacitor during a charge period before the display period begins. This ensures that when noise occurs during the display period, the capacitor already has sufficient charge to rapidly restore the potential within the normal range, rather than needing to charge from scratch during the critical display period.
Solution Approach 2:
The patent implements beforehand cushioning by providing a dedicated charge period that accumulates charge in the capacitor in advance. This creates a buffer or cushion of available charge that can be quickly deployed to counteract noise effects during the display period, preventing potential excursions outside the normal range rather than merely responding to them.
2Speed
If rectifying elements are added to rapidly stabilize potential, then response speed is improved, but device complexity increases
Solution Approach 1:
The patent uses rectifying elements as intermediary components between the capacitor and the signal line. These rectifying elements act as mediators that enable rapid charge transfer when needed while presenting a simple interface to the rest of the circuit. The rectifying elements translate the capacitor's charge into rapid potential stabilization without requiring complex control logic or additional active components.
3Reliability
If the capacitor charge period is extended to ensure sufficient charge, then reliability is improved, but the write time increases
Solution Approach 1:
The patent applies dynamics by making the charge transfer process adaptive rather than static. The rectifying elements enable the capacitor to charge rapidly when needed (during noise events) while allowing the charge period to be shorter in normal operation. The system dynamically adjusts the charge transfer rate based on the rectifying elements' conduction characteristics, achieving both speed and reliability without extending the write time.
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 effectively stabilizes signal current potentials, reducing write time and preventing luminance variations, thereby enhancing the reliability and accuracy of light emission in self-light emitting displays.
Implementation Method 1
a current flows to the rectifying element until the potential of the wiring becomes within the normal range
Implementation Method 2
a capacitor for holding a gate potential of the transistor
Data Source
AI summary
When writing a signal current from a current source to a current source circuit, noise occurs in some cases in a wiring through which a current flows, which may cause a potential of the wiring to be outside the normal range. As the potential does not turn back within the normal range easily at this time, writing to the current source circuit is delayed. According to the invention, when the potential becomes outside the normal range due to noise occurring in a wiring through which a current flows when writing a signal current from a current source to a current source circuit, a current is supplied from other than the current source, thereby the potential of the wiring can turn back within the normal range rapidly.