OLED Display Overlapping Layer for Transistor Variation Compensation
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Solution Overview
Problem
Organic light emitting diode (OLED) displays face challenges in maintaining uniform display quality due to variations in the characteristics of driving transistors, which affect charging rates and image rendering.
Innovation Solution
The implementation of an overlapping layer in the OLED display that receives specific voltages during different operational periods, including a driving voltage and an initialization voltage, to mitigate the effects of transistor characteristic deviations, thereby enhancing data range and charging efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional driving transistor structure is used, then the device complexity is low, but the display uniformity deteriorates due to transistor characteristic variations
Solution Approach 1:
The gate electrode is divided into two separate gate electrodes (first gate electrode and second gate electrode), with each gate electrode connected to independent voltage lines. This segmentation allows independent control of the gate voltages, enabling compensation for transistor characteristic variations and improving display uniformity across the display panel.
Solution Approach 2:
The patent applies different voltages (first voltage and second voltage) to the two gate electrodes independently. By changing the voltage parameters applied to each gate electrode based on their respective positions and transistor characteristics, the system compensates for variations in threshold voltage and other parameters, thereby improving display uniformity.
2Productivity
If the overlapping layer is not used, then the device complexity is low, but the charging rate of data voltage deteriorates
Solution Approach 1:
The overlapping layer is introduced as an intermediary component between the substrate and the active transistor structures. This layer facilitates improved electrical characteristics and enhances the charging rate of data voltage by providing an optimized conduction path, while its simple planar structure minimizes the increase in overall device complexity.
Data Source
AI summary
An organic light emitting diode display includes: a substrate; an overlapping layer on the substrate; a pixel on the substrate and the overlapping layer; and a scan line, a data line, a driving voltage line, and an initialization voltage line that are connected to the pixel. The pixel includes: an organic light emitting diode; a second transistor connected to the scan line and the data line; a driving transistor including a gate electrode, an input terminal, and an output terminal, and to apply a current to the organic light emitting diode from the output terminal; and a voltage application transistor to apply a voltage to the overlapping layer. An output of the second transistor is connected to the input terminal of the driving transistor, and the overlapping layer is between the driving transistor and the substrate while overlapping with the driving transistor on a plane.