Light Extraction Layer Lens Height Ratio for OLED Luminance
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Solution Overview
Problem
Current organic light emitting display devices face limitations in achieving high luminance, particularly due to the inefficiency of the white sub-pixel in contributing to overall brightness.
Innovation Solution
The implementation of a light extraction layer with first and second lenses on the substrate's outer surface, where the first lens corresponds to the emission area and the second lens corresponds to the non-emission area of the white sub-pixel, enhances light out-coupling efficiency by refracting trapped light outward.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a white sub-pixel is added to increase luminance, then the overall brightness of the display is improved, but the light out-coupling efficiency deteriorates due to light being trapped inside the substrate
Solution Approach 1:
The patent applies curvature by forming lens structures (convex shapes) on the light extraction layer. These curved surfaces refract the light emitted from the white sub-pixel, changing its propagation direction from being trapped within the substrate to being extracted outward. The spherical/convex geometry of the lenses enables effective light out-coupling while maintaining high luminance output.
2Illumination intensity
If a light extraction layer with lenses is added to improve light out-coupling, then the luminance is improved, but the device complexity increases
Solution Approach 1:
The light extraction layer serves multiple functions simultaneously: it acts as both a structural element and an optical element. The lens structures formed on this layer perform light extraction, light focusing, and light direction control in a single integrated component, rather than requiring separate elements for each function. This multi-functionality reduces overall device complexity despite adding the light extraction capability.
Solution Approach 2:
The patent changes the physical parameters of the light extraction layer by forming convex lens structures with specific heights and curvature radii. By optimizing these geometric parameters (height ratio between first and second lenses, curvature radius relative to sub-pixel pitch), the system achieves high light out-coupling efficiency without requiring excessively complex structures. The parameter optimization balances performance improvement with structural simplicity.
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
This configuration significantly improves luminance and emission efficiency by effectively refracting and focusing light, thereby enhancing the display's brightness and color accuracy.
Implementation Method 1
a light extraction layer located on an outer surface of the substrate corresponding to a transmission direction of a light emitted from the first light emitting diode, wherein the light extraction layer includes a first lens corresponding to the emission area and a second lens corresponding to the non-emission area
Data Source
AI summary
An organic light emitting display device includes a substrate in which a pixel is defined, the pixel including a white sub-pixel which includes an emission area and a non-emission area; a first light emitting diode located in the white sub-pixel; and a light extraction layer located on an outer surface of the substrate corresponding to a transmission direction of a light emitted from the first light emitting diode, wherein the light extraction layer includes a first lens corresponding to the emission area and a second lens corresponding to the non-emission area, wherein a height of the first lens is greater than a height of the second lens.