OLED Subpixel Circuit Removing Storage Capacitors and Parasitic Effects
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Solution Overview
Problem
Conventional organic light-emitting display devices suffer from luminance deviations between subpixels due to changes in transistor characteristics over time, which are exacerbated by the influence of parasitic capacitors during data writing, leading to poor image quality.
Innovation Solution
A display device design that integrates the scanning signal line and emission control signal line into a single structure, allowing direct data writing to the driving transistor without relying on storage capacitors, thus minimizing the impact of parasitic capacitors and ensuring accurate data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a storage capacitor is used to store charge corresponding to image displaying data voltage during data write period, then data can be held for driving the OLED, but the parasitic capacitor influences the charge storage, resulting in luminance deviations and poor image quality
Solution Approach 1:
The patent removes the storage capacitor from the subpixel circuit structure, extracting the harmful parasitic capacitance element that causes luminance deviations. By eliminating the storage capacitor, the parasitic capacitance that was coupled with it is also removed, solving the problem of charge storage inaccuracy without affecting the overall data holding function through alternative circuit design
2Reliability
If separate scanning signal line and emission control signal line are used, then signal transmission is reliable, but the number of conductive lines increases, reducing aperture ratio
Solution Approach 1:
The patent merges the scanning signal line and emission control signal line into a single integrated conductive line structure. This consolidation reduces the total number of signal lines required, thereby increasing the aperture ratio of the display panel while maintaining reliable signal transmission through the integrated design that provides both scanning and emission control functions
Data Source
AI summary
A subpixel circuit of a display device comprises a driving transistor, a first transistor controlled by the scanning signal and electrically connected to gate and drain nodes of the driving transistor; a second transistor controlled by the scanning signal and electrically connected to a source node of the driving transistor and the data line; a third transistor controlled by the emission control signal and electrically connected to a high potential voltage supply line and the source node of the driving transistor; a fourth transistor controlled by the emission control signal and electrically connected to the drain node of the driving transistor and the light-emitting element; and a fifth transistor controlled by the scanning signal and electrically connected to an initializing voltage supply line and the light-emitting element. The number of signal lines are reduced by forming a scanning signal line and an emission control signal line into an integrated structure.