OLED Encapsulation Substrate with Patterned ITO for Touch Sensing
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Solution Overview
Problem
Organic light emitting display devices with internal electrostatic capacitive touch panels face increased thickness and luminance degradation due to indium tin oxide (ITO) electrodes absorbing light emitted from organic light emitting diodes (OLEDs).
Innovation Solution
A patterned encapsulation substrate with openings corresponding to the emission layer of OLEDs is used, allowing for a touch panel function without increasing thickness and maintaining luminance by positioning ITO patterns to allow light to pass through without significant reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If ITO electrodes are disposed on the entire surface of the encapsulation substrate to provide touch panel function, then touch panel function is achieved, but light emitted from OLEDs is absorbed by the ITO electrodes, degrading luminance
Solution Approach 1:
The ITO electrode layer is segmented into a patterned structure with openings corresponding to the emission layers of OLEDs. This segmentation allows light to pass through the openings while the ITO pattern portions provide touch panel functionality, thus resolving the contradiction between achieving touch panel function and maintaining luminance.
Solution Approach 2:
The ITO electrode is applied selectively in specific regions (patterned areas) rather than uniformly across the entire encapsulation substrate. The local quality of the ITO layer varies: it is present in regions where touch sensing is needed and absent in regions where light emission occurs, thereby simultaneously achieving touch panel function and preserving luminance.
2Adaptability or versatility
If the encapsulation substrate is made thicker to embed the touch panel function, then touch panel function is achieved, but the thickness of the display device increases
Solution Approach 1:
The touch panel function is merged with the encapsulation substrate by forming the ITO pattern layer directly on the inner surface of the encapsulation substrate. This integration eliminates the need for separate touch panel layers, thereby achieving touch panel functionality without increasing the overall thickness of the display device.
Solution Approach 2:
The encapsulation substrate is given multiple functions: it serves both as the protective encapsulation layer for the OLED and as the substrate for the touch panel electrode. This multi-functionality allows the encapsulation substrate to provide both protection and touch sensing capability without requiring additional thickness.
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
Enables a touch panel function in organic light emitting display devices without thickness increase and with improved luminance by strategically patterning ITO on the encapsulation substrate to align with OLED emission layers, allowing light to pass through without absorption.
Implementation Method 1
a capacitive pattern layer on a side of the encapsulation substrate facing the display unit
Implementation Method 2
openings are formed in the ITO pattern corresponding to an emission layer of an organic light emitting diode (OLED), so that light emitted from organic light emitting diodes (OLEDs) is absorbed by the ITO electrodes
Data Source
AI summary
An organic light emitting display device having an electrostatic capacitive type touch panel function with reduced thickness and improved luminance. A display panel of the organic light emitting display device includes a substrate, a display unit having a plurality of pixels on the substrate, and a touch sensing unit on the display unit. The touch sensing unit includes an encapsulation substrate and a capacitive pattern layer on a side of the encapsulation substrate facing the display unit. The capacitive pattern layer has a plurality of openings corresponding in position to the plurality of pixels.