OLED Shield Unit for Parasitic Capacitance Reduction
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Solution Overview
Problem
High-resolution organic light emitting display devices suffer from image quality deterioration due to parasitic capacitance between the data line and the gate electrode of the driving thin film transistor, leading to crosstalk and reduced luminance, as the gap between these components decreases, causing a coupling effect that affects the driving current and image signal.
Innovation Solution
Incorporation of a shield unit that overlaps the data line and is extended from the active layer of the driving thin film transistor, reducing the parasitic capacitance between the data line and the gate electrode, thereby minimizing the coupling effect and improving the current holding ratio without additional processing steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the gap between the data line and the gate electrode is reduced to improve resolution, then the resolution is improved, but the parasitic capacitance increases causing coupling effect and image quality deterioration
Solution Approach 1:
A shield electrode is introduced as an intermediary component between the data line and the gate electrode. This shield electrode acts as a mediator that blocks the electric field coupling between these two conductors, reducing the parasitic capacitance. The shield electrode is connected to a reference potential (ground or VDD) to effectively terminate the electric field lines, preventing them from coupling between the data line and gate electrode.
Solution Approach 2:
The harmful parasitic capacitance effect is extracted and isolated by introducing the shield electrode. The shield electrode separates the electric field interaction between the data line and gate electrode, effectively removing the direct coupling path. This allows the system to maintain small gaps for high resolution while eliminating the harmful capacitive coupling through the intermediate shielding structure.
2Measurement precision
If the gap between lines and pixel circuit is reduced to improve resolution, then the resolution is improved, but the coupling effect between data line and driving transistor increases causing crosstalk and luminance deterioration
Solution Approach 1:
The shield electrode serves as an intermediary barrier between the data line and the driving transistor components. By positioning the shield electrode between these elements and connecting it to a stable reference potential, the electric field fluctuations from the data line are blocked from affecting the gate electrode and driving transistor, thereby preventing crosstalk and maintaining reliable image quality.
Solution Approach 2:
The shield electrode provides preliminary protection by blocking the harmful electric field coupling before it can affect the driving transistor and cause crosstalk. The shield is positioned upstream in the electric field path, preemptively terminating the field lines and preventing the coupling effect from developing, thus maintaining signal integrity and image quality.
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
The shield unit effectively decreases parasitic capacitance, reducing crosstalk and maintaining consistent driving current and luminance, thereby enhancing image quality in high-resolution organic light emitting display devices.
Implementation Method 1
the pixel circuit and the lines form a parasitic capacitor and a plurality of signals is coupled
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
Provided is an organic light emitting display device. The organic light emitting display device includes: a driving thin film transistor; a storage capacitor; a first pattern electrode; an anode; a second pattern electrode; and a patterned semiconductor layer. The driving thin film transistor includes an active layer and a gate electrode. The storage capacitor includes a first electrode and a second electrode. The first pattern electrode includes the gate electrode and the first electrode. The anode is disposed on the driving thin film transistor and the storage capacitor. The second pattern electrode is connected with an anode contact part which connects an output electrode connected with the active layer and the anode. The patterned semiconductor layer includes the second pattern electrode, the active layer having semiconductive characteristic, and a shield unit having conductive characteristic.