OLED Cathode Protrusion Reduces Parasitic Capacitance
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Solution Overview
Problem
The parasitic capacitance between the cathode electrodes and signal transmission lines in organic light emitting displays disrupts the smooth flow of signals, reducing display quality due to the overlapping configuration of cathode electrodes with signal lines on the substrate.
Innovation Solution
The design includes a second electrode that protrudes towards a contact unit on the substrate, with a concave unit reducing the area overlapping the wiring line unit, thereby minimizing parasitic capacitance and improving signal flow, and a moisture absorbing layer is added to prevent light emission reduction from moisture exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cathode electrodes are formed to cover all pixels on the substrate, then the OLED structure is complete and functional, but parasitic capacitance is produced between the cathode electrodes and signal transmission lines, disrupting signal flow and reducing display quality
Solution Approach 1:
The harmful overlapping region between the cathode electrode and signal transmission line is extracted and removed by forming a concave unit in the cathode electrode. This extraction eliminates the source of parasitic capacitance while preserving the essential coverage function of the cathode electrode over the pixel region.
Solution Approach 2:
The cathode electrode is designed with non-uniform local properties: it maintains full coverage over the pixel region for proper OLED operation, but introduces a localized concave unit in the overlapping region with signal transmission lines to reduce parasitic capacitance. This local modification optimizes both electrical performance and signal integrity.
2Ease of manufacture
If the cathode electrode covers the entire pixel area, then the OLED structure is complete, but the overlapping with signal lines causes parasitic capacitance that disrupts signal flow
Solution Approach 1:
The problematic overlapping portion is extracted from the cathode electrode by forming a concave unit, removing the source of parasitic capacitance while maintaining the overall structural integrity and completeness of the OLED device.
Solution Approach 2:
A localized concave modification is introduced in the cathode electrode at the specific region where it overlaps with signal transmission lines, creating different local properties: full coverage over pixels for structural completeness, and reduced overlap with signal lines to minimize parasitic capacitance.
Data Source
AI summary
An organic light emitting display is disclosed. According to some aspects, the display includes a substrate having a display region and a peripheral region that surrounds the display region. The display further includes a pixel in the display region, and a contact unit in the peripheral region. The contact unit is configured to receive a common power signal from an external power source. A wiring line unit on the substrate provides a driving signal to the pixel. The pixel includes a first electrode provided on the substrate, an organic light emitting layer provided on the first electrode, and a second electrode that protrudes toward the contact unit on a plane to be electrically coupled to the contact unit. As a result, the area in which the second electrode overlaps the wiring line unit in the peripheral region is reduced and the parasitic capacitance that may be generated between the second electrode and the wiring line may be reduced.