Organic EL Display Driving Circuit Potential Correction
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Solution Overview
Problem
In organic EL display devices driven by a 2Tr/1C drive circuit, achieving sufficient potential correction and maintaining luminance uniformity is challenging due to the short scanning period, which results in inadequate [period-TP(2)4 duration and insufficient potential correction value, leading to deterioration in display uniformity.
Innovation Solution
A display apparatus and method that adjust the length of [period-TP(2)4 by applying an auxiliary video signal followed by a video signal, allowing for accelerated or decelerated potential change on the second node, enabling favorable mobility correction even with short scanning periods, thereby improving luminance uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the scanning period is shortened to increase scanning speed, then productivity is improved, but the duration of [period-TP(2)4 is reduced, resulting in insufficient potential correction and deterioration of manufacturing precision
Solution Approach 1:
The patent applies preliminary action by performing threshold voltage cancel processing before the write processing period [period-TP(2)4]. During this preliminary phase, the potential of the second node is adjusted in advance to account for the short scanning period, ensuring that sufficient potential correction is achieved even when the main writing period is compressed. This allows the system to maintain manufacturing precision while operating at high scanning speeds.
2Manufacturing precision
If the duration of [period-TP(2)4 is increased to improve potential correction, then manufacturing precision is improved, but the scanning period becomes longer, reducing productivity
Solution Approach 1:
The patent performs threshold voltage cancel processing as a preliminary action before the write processing period. This preliminary adjustment of the second node potential ensures that the necessary potential correction is achieved in advance, allowing the write processing period [period-TP(2)4 to be kept short while still maintaining luminance uniformity and manufacturing precision.
3Manufacturing precision
If the potential correction value is increased to improve luminance uniformity, then manufacturing precision is improved, but the time required for potential correction increases, reducing productivity
Solution Approach 1:
The patent performs threshold voltage cancel processing as a preliminary action during the initialization phase, before the write processing period begins. This preliminary adjustment establishes the correct potential relationship between nodes in advance, enabling rapid potential correction during the write phase without sacrificing luminance uniformity. The potential correction is achieved efficiently because the groundwork is already laid during the preliminary phase.
Solution Approach 2:
The patent utilizes parameter changes by dynamically adjusting the potential of the second node based on the relationship between video signal levels and the light-emitting portion's threshold voltage. By changing the potential parameter in response to signal conditions, the system achieves accurate potential correction and maintains luminance uniformity without requiring excessive correction time, thus preserving productivity.
Data Source
AI summary
Driving a display apparatus by performing write processing for applying an auxiliary video signal to a corresponding data line, then, applying a video signal, instead of the auxiliary video signal, to the corresponding data line, and in a state where a predetermined drive voltage is applied from a power supply portion to one area of the source and drain areas of a drive transistor, applying a voltage based on the auxiliary video signal and a voltage based on the video signal from the corresponding data line to the gate electrode of the drive transistor through a write transistor which is turned on in response to a scanning signal from the corresponding scanning line.