OLED Pixel Electrode Layout for Side Color Shift Reduction
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Solution Overview
Problem
Organic light-emitting display devices face issues with lateral side color shift and brightness due to overlapping transistors and capacitors, leading to poor visibility and color shifts when viewed from different angles.
Innovation Solution
The design includes a pixel defining layer with an opening that exposes a portion of the pixel electrode, and a reference line overlapping the pixel electrode with an insulating layer, arranged to minimize lateral side color shift by ensuring bilateral symmetry and uniform parasitic capacitance across pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If transistors and capacitors are arranged to overlap with pixel electrodes to increase resolution, then device integration is improved, but color shift and brightness uniformity deteriorate
Solution Approach 1:
The patent applies asymmetry by intentionally designing the pixel defining layer opening to be offset from the center of the pixel electrode. This asymmetric arrangement compensates for the asymmetric interference caused by overlapping transistors and capacitors, thereby restoring brightness uniformity across the display while maintaining high device integration.
2Device complexity
If transistors and capacitors are arranged to overlap with pixel electrodes, then device complexity is reduced, but color coordinate consistency deteriorates
Solution Approach 1:
The pixel defining layer opening is deliberately positioned asymmetrically relative to the pixel electrode center. This asymmetric design counterbalances the asymmetric parasitic capacitance effects from overlapping circuit elements, ensuring consistent color coordinates across different pixels and viewing angles while maintaining a relatively simple device structure.
3Ease of operation
If viewing angle is increased to improve visibility, then field of view is improved, but color shift increases
Solution Approach 1:
By offsetting the pixel defining layer opening from the pixel electrode center, the patent creates an asymmetric configuration that compensates for angular-dependent color shifts. This allows the display to maintain consistent color coordinates across a wider viewing range, improving visibility without sacrificing color accuracy.
Data Source
AI summary
An organic light-emitting display device includes a plurality of pixels, each of which includes an organic light-emitting device including a pixel electrode, an organic emission layer, and an opposing electrode; a pixel defining layer covering an edge of the pixel electrode and being configured to define a light-emission region by having an opening which exposes a portion of the pixel electrode; and a reference line overlapping the pixel electrode with an insulating layer between the reference line and the pixel electrode and extending in a first direction. The reference line overlaps with a center point of the opening, and the opening is shifted to one side of the pixel electrode in a second direction perpendicular to the first direction.