Auxiliary Common Electrode Layout for Uniform Inorganic LED Displays
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Solution Overview
Problem
Display devices using inorganic light emitting diodes experience luminance unevenness due to IR drop in the common electrode, which is exacerbated by increased current, particularly in larger panels.
Innovation Solution
Incorporation of an auxiliary electrode with lower resistance than the common electrode, positioned to minimize overlap with light emitting elements and connected to the common electrode through penetrating connections, along with a transparent conductive layer to reduce IR drop and enhance luminance uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the current is increased to enhance display performance, then the luminance output is improved, but the IR drop in the common electrode increases causing luminance unevenness
Solution Approach 1:
The common electrode is segmented by introducing an auxiliary electrode that divides the current path. The auxiliary electrode is positioned to overlap with the common electrode in plan view, creating multiple parallel current conduction paths that reduce the overall resistance and mitigate IR drop across the display panel.
Solution Approach 2:
The auxiliary electrode acts as an intermediary conductive element between the pixel electrodes and the common electrode. It provides an additional current distribution pathway that mediates the current flow, reducing the voltage drop across the common electrode and ensuring more uniform luminance distribution.
2Reliability
If the common electrode thickness is increased to reduce resistance, then the IR drop is reduced, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The electrode system uses a composite structure comprising the common electrode and the auxiliary electrode made of different materials. The auxiliary electrode is formed with a material having lower specific resistance than the common electrode, creating a composite conductive system that achieves superior electrical conductivity without increasing the common electrode thickness or 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
The auxiliary electrode effectively reduces IR drop, minimizing luminance unevenness and ensuring consistent brightness across the display panel.
Implementation Method 1
an auxiliary electrode disposed on the common electrode and not overlapping the light emitting elements in a thickness direction of the substrate. The auxiliary electrode may be made of a material having a resistance lower than a resistance of the common electrode.
Implementation Method 2
light emitting elements each disposed on a corresponding one of the plurality of pixel electrodes
Data Source
AI summary
A display device includes a substrate including a display area and a non-display area, a plurality of pixel electrodes disposed on the substrate in the display area, light emitting elements each disposed on a corresponding one of the plurality of pixel electrodes, a common electrode disposed on the light emitting elements and commonly connected to a plurality of pixels, and an auxiliary electrode disposed on the common electrode and not overlapping with the light emitting elements in a thickness direction of the substrate.