OLED Driving Transistor Source Electrode Overlap for Voltage Stabilization
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Solution Overview
Problem
OLED displays experience a screen overlapping or dragging phenomenon due to voltage changes caused by parasitic capacitance between the gate and source electrodes of the driving transistor, leading to suboptimal luminance and display quality.
Innovation Solution
The design incorporates an assistance capacitor with a larger capacitance than the parasitic capacitor, achieved by optimizing the overlap and width of the driving source electrode with respect to the driving voltage line and data line, which helps to stabilize the voltage of the source electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the OLED display uses a conventional driving transistor structure without assistance capacitor, then the device complexity is low, but the screen overlapping or dragging phenomenon occurs due to voltage changes from parasitic capacitance
Solution Approach 1:
An assistance capacitor is introduced as an intermediary element between the gate electrode and source electrode of the driving transistor. This capacitor mediates the voltage changes caused by parasitic capacitance, preventing the screen overlapping or dragging phenomenon while maintaining a relatively simple overall structure.
Solution Approach 2:
The assistance capacitor is designed to preemptively counteract the voltage changes that would otherwise occur due to parasitic capacitance during initialization. By providing opposite action in advance, the harmful voltage fluctuations are prevented before they can cause display artifacts.
2Stability of the object's composition
If the width of driving source electrode overlapping the driving voltage line is increased to form larger assistance capacitor, then the voltage stability improves, but the manufacturing precision requirements increase
Solution Approach 1:
The width of the driving source electrode in the overlapping region is optimized to a specific range (w3>w4) to achieve the desired capacitance value. By carefully controlling this geometric parameter, the assistance capacitor provides sufficient voltage stabilization without requiring excessive manufacturing precision.
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 solution effectively reduces the voltage change of the source electrode, thereby improving the screen's luminance consistency and preventing the screen overlapping or dragging phenomenon, enhancing the overall display quality.
Implementation Method 1
the driving source electrode overlaps the driving voltage line to form an assistance capacitor
Implementation Method 2
an electron injected from one electrode and a hole injected from the other electrode are coupled with each other in the organic emission layer to generate an exciton, and the exciton emits energy to emit light
Data Source
AI summary
An organic light-emitting diode (OLED) display includes a substrate, a scan line disposed over the substrate and configured to transmit a scan signal, a data line crossing the scan line and configured to transmit a data voltage a driving voltage line crossing the scan line and configured to transmit a driving voltage, a switching transistor connected to the scan line and the data line, a driving transistor connected to the switching transistor and including a driving gate electrode, a driving source electrode, and a driving drain electrode, and an OLED electrically connected to the driving transistor, wherein the driving source electrode at least partially overlaps the data line in the depth dimension of the OLED display so as to form an assistance capacitor.