OLED Pixel Circuit Layout for Kickback Voltage Stabilization
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Solution Overview
Problem
In organic light-emitting display devices, the voltage of the gate electrode of a transistor can be excessively reduced due to kickback voltage characteristics, which complicates the implementation of black luminance and may require reducing supply voltages beyond conventional power supply limits.
Innovation Solution
The implementation includes a display device with a light-emitting diode, transistors, and parasitic capacitors, where the conductive pattern overlaps scan lines, increasing the overlapping area and capacitance to manage kickback voltages, and using PMOS and NMOS transistors in combination to compensate for threshold voltage variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If NMOS transistors are used to replace PMOS transistors, then device performance is improved, but kickback voltage characteristics deteriorate causing excessive gate electrode voltage reduction
Solution Approach 1:
The patent introduces a conductive pattern as an intermediary element between the scan lines and the gate electrode. This conductive pattern includes a stem part extending in one direction and a branch part branching from the stem part and overlapping the first scan line, creating parasitic capacitance that acts as a buffer to mitigate the harmful kickback voltage effects while preserving the performance benefits of NMOS transistors.
2Reliability
If conductive pattern with stem part and branch part is added, then gate electrode voltage stability is improved, but device complexity increases
Solution Approach 1:
The conductive pattern serves multiple functions simultaneously: it acts as an electrode for creating parasitic capacitance, provides structural support, and facilitates electrical connections. The stem part and branch part configuration allows a single conductive pattern element to perform voltage stabilization across multiple gate electrodes, reducing the need for separate components and thereby limiting the increase in device complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration effectively prevents excessive reduction of the gate electrode voltage due to kickback, allowing for black luminance implementation using conventional external voltage sources, thereby reducing manufacturing costs and enhancing display performance.
Implementation Method 1
a first parasitic capacitor formed between the gate electrode of the second transistor and the gate electrode of the first transistor; and a second parasitic capacitor formed between the gate electrode of the third transistor and the gate electrode of the first transistor
Data Source
AI summary
A display device including a light-emitting diode, a first transistor, a second transistor, a data line connected to the second transistor and configured to transmit a data signal, a third transistor, a first signal line connected to a gate electrode of the second transistor and configured to transmit a first signal, a second signal line connected to a gate electrode of the third transistor and configured to transmit a second signal, and a connect portion connected to a gate electrode of the first transistor and an electrode of the third transistor, in which the connect portion overlaps the first signal line and the second signal line, and an overlapping area between the connect portion and the first signal line is different from an overlapping area between the connect portion and the second signal line.