OLED Pixel Circuit Driving Method for Threshold Voltage Correction
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Solution Overview
Problem
In organic electroluminescence display devices, increasing resolution and refresh rate leads to shorter time periods for threshold voltage canceling processing, resulting in insufficient correction of transistor characteristics and reduced image luminance uniformity.
Innovation Solution
A driving method for organic electroluminescence emission portions using a drive circuit with a drive transistor, a write transistor, and a capacitor, where the drive transistor has one source/drain region connected to a power source and the other to the anode electrode, and the gate electrode is connected to the write transistor, allowing for extended threshold voltage canceling processing time without requiring the drive transistor to be turned off.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If resolution and refresh rate are increased, then display quality is improved, but time period for threshold voltage canceling processing becomes shorter
Solution Approach 1:
The patent applies preliminary action by performing threshold voltage canceling processing during the non-scanning period, specifically in the time interval between the completion of scanning and the start of data writing. This allows the correction process to be executed in advance before the main display operation, ensuring sufficient correction time even at high refresh rates without compromising display quality.
2Productivity
If time period for threshold voltage canceling processing is shortened, then refresh rate can be increased, but correction of transistor characteristics becomes insufficient
Solution Approach 1:
The patent employs dynamics by making the drive transistor remain in the ON-state throughout the threshold voltage canceling processing, allowing the correction to be performed dynamically during the non-scanning period rather than requiring the transistor to be turned off. This dynamic approach enables sufficient correction time to be allocated within each scanning period, maintaining high refresh rates while ensuring adequate correction precision.
3Manufacturing precision
If drive transistor is turned off during threshold voltage canceling processing, then processing can be performed, but luminance uniformity is reduced
Solution Approach 1:
The patent applies continuity of useful action by keeping the drive transistor in the ON-state during threshold voltage canceling processing, allowing the correction to be performed continuously without interruption to the current flow. This continuous operation maintains stable luminance output while still enabling the threshold voltage correction to be executed, eliminating the need to turn off the transistor and thereby preserving luminance uniformity.
Data Source
AI summary
A pixel circuit and driving method are disclosed, wherein the pixel circuit comprises a first transistor, a second transistor, and a capacitor. The first transistor is connected between a power source and a light emission portion, and the second transistor is connected to a data line. The capacitor is initialized according to a potential, and a video signal is applied from the data line to the capacitor through the second transistor. For driving, an initialization voltage is applied to the data line and the video signal is supplied to the data line, with the second transistor being turned ON prior to applying the initialization voltage to the data line.