OLED Pixel Circuit Leakage Current Diversion
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Solution Overview
Problem
High-temperature operation of display devices leads to increased leakage current through turned-off transistors, causing crosstalk phenomena due to reduced channel lengths and shifting threshold voltages, which affects the luminance and viewing angle of OLED displays.
Innovation Solution
Incorporating a fourth transistor connected between the second node and a second voltage, and an eighth transistor diode-connected to the second or third node, which directs leakage currents away from the main transistor, thereby preventing voltage reduction and crosstalk by utilizing specific voltage supply configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the transistor size is reduced to integrate more pixels in a narrow region, then the display resolution is improved, but the channel length is reduced which causes increased leakage current through turned-off transistors
Solution Approach 1:
A fourth transistor is introduced as an intermediary component connected between the second node and second voltage. This additional transistor acts as a mediator to divert leakage current away from the main transistor channel, preventing the leakage from affecting the pixel's voltage levels and causing crosstalk between adjacent pixels.
2Adaptability or versatility
If the display device is operated at high temperature, then the display can function in various environmental conditions, but the threshold voltage shifts causing increased leakage current through turned-off transistors
Solution Approach 1:
The invention converts the harmful effect of temperature-induced threshold voltage shifts into a beneficial configuration. By adding the fourth transistor connected to the second voltage, the circuit is designed to utilize the leakage current that inevitably occurs at high temperatures and redirect it through the fourth transistor to a safe node, preventing it from causing crosstalk or display defects.
3Length of moving object
If the channel length is reduced to reduce transistor size, then more pixels can be integrated, but current leakage increases through the turned-off transistor
Solution Approach 1:
The invention extracts the leakage current path from the main transistor by introducing a separate fourth transistor. The fourth transistor provides an alternative path that diverts the leakage current away from the pixel's critical nodes, effectively separating the harmful leakage effect from the useful display function.
Data Source
AI summary
A pixel includes: an organic light emitting diode; a first transistor including a gate that is connected to a first node, wherein the first transistor is connected between a second node and a third node; a second transistor including a gate that is connected to a corresponding scan line, wherein the second transistor is connected between a data line and the second node; a storage capacitor connected between the first node and a first voltage; a third transistor including a gate that is connected to the corresponding scan line, the third transistor is connected between the first node and the third node; and a fourth transistor connected between a first end of the first transistor and a second voltage.