Display Light Extraction Structure for Luminance Uniformity
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Solution Overview
Problem
In self-luminous display devices, a significant portion of light generated by light emitting devices is trapped inside the display panel, leading to reduced luminance and image quality, particularly in high-resolution panels, and luminance deviation among subpixels.
Innovation Solution
A display device with a light extraction structure featuring a common electrode with inclined surfaces and a specific arrangement of pixel electrodes, along with an intermediate layer and insulating layers, enhances light emission towards the viewing surface and compensates for luminance deviations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If light emitting devices generate light in a self-luminous display panel, then the display device can emit light on its own, but a significant portion of light is trapped inside the display panel leading to reduced luminance
Solution Approach 1:
The common electrode is configured with inclined surfaces instead of a flat structure. These inclined surfaces redirect trapped light toward the viewing surface, improving light extraction efficiency and luminance by changing the angular distribution of emitted light.
Solution Approach 2:
The patent introduces vertical positioning differences among pixel electrodes (first, second, third pixel electrodes at different heights) to create three-dimensional light extraction paths. This dimensional variation allows light to escape through multiple angles and reduces total internal reflection.
2Loss of energy
If multiple pixel electrodes are arranged in different positions and heights, then light extraction efficiency is improved, but the device structure becomes more complex
Solution Approach 1:
The common electrode serves multiple functions: it acts as a reflective electrode, provides structural support, and functions as a light extraction element through its inclined surfaces. This multi-functionality reduces the need for additional dedicated light extraction components, simplifying the overall structure.
Solution Approach 2:
The patent combines the light extraction function with the existing pixel electrode and common electrode structures rather than adding separate light extraction components. The inclined surfaces are integrated into the common electrode, merging structural and optical functions.
3Reliability
If light is trapped inside the display panel, then the internal light path increases, but luminance deviation among subpixels occurs and image quality deteriorates
Solution Approach 1:
Different pixel electrodes are positioned at different vertical heights (first pixel electrode higher than second, third pixel electrode at intermediate height) to locally optimize light extraction for each subpixel. This local variation compensates for luminance deviations and ensures uniform image quality across the display panel.
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 structure increases light extraction efficiency, improves image quality by reducing luminance deviation, and potentially lowers power consumption.
Implementation Method 1
a common electrode on the intermediate layer and including a reflective electrode material
Data Source
AI summary
A display device according to an example of the present disclosure can include a substrate, a first protective layer on the substrate, a lower insulating layer on the first protective layer, a first upper insulating layer on the lower insulating layer, a second upper insulating layer on the lower insulating layer and spaced apart from the first upper insulating layer in a first direction, a first pixel electrode on the first upper insulating layer, a second pixel electrode on the lower insulating layer and disposed between one side of the first upper insulating layer and another side of the second upper insulating layer, and a third pixel electrode on the second upper insulating layer.