Sloped Pixel Electrode for OLED Light Collection
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Solution Overview
Problem
Organic light-emitting display apparatuses face challenges in achieving a high aperture ratio and efficient light sensing due to the limited light emission towards the photo sensors, especially in top emission-type displays where light is primarily emitted away from the substrate, resulting in reduced data collection and increased spot occurrence over time.
Innovation Solution
The design incorporates a second pixel with a pixel electrode having a slope and an asymmetrical organic insulating layer, which increases light emission towards photo sensors by diffusing light along the slope, and a light blocking layer to prevent leakage, enhancing the aperture ratio and light collection efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If light is primarily emitted away from the substrate in top emission-type displays, then the aperture ratio can be increased, but the light emission towards photo sensors is reduced
Solution Approach 1:
The pixel electrode is designed with a sloped surface instead of a flat surface, changing the dimensional orientation of light emission. The slope directs light that would otherwise be emitted away from the substrate toward the photo sensors located at the edges of the display area, effectively utilizing a different spatial dimension for light redirection.
Solution Approach 2:
The organic insulating layer is designed with asymmetrical thickness, being thicker at one end and thinner at the other end of the pixel electrode. This local variation in insulating layer quality creates corresponding variations in light emission intensity and direction, with the thicker region directing more light toward the photo sensors.
2Area of stationary object
If photo sensors are arranged in the outer area of the display area, then the display area can be maximized, but the light collection efficiency is reduced
Solution Approach 1:
The sloped pixel electrode redirects light in a directional manner toward the edge-located photo sensors, compensating for the increased distance by changing the light propagation angle. This dimensional redirection allows effective light collection despite the photo sensors being positioned in the outer area.
Solution Approach 2:
The asymmetrical organic insulating layer creates asymmetric light emission patterns that are directed toward the specific location of the photo sensors in the outer area. The thicker end of the insulating layer corresponds to the region where light redirection is most needed to reach the edge-located sensors.
3Illumination intensity
If the pixel electrode has a sloped structure, then light emission towards photo sensors is increased, but the manufacturing complexity is increased
Solution Approach 1:
The sloped structure is integrated directly into the pixel electrode formation process itself, rather than being added as a separate component. The pixel electrode and the sloped light-directing structure are merged into a single monolithic structure, simplifying manufacturing despite the complex geometry.
Solution Approach 2:
The pixel electrode serves dual functions: as the standard electroluminescent component and as a light-directing structure with a sloped surface. This multi-functionality eliminates the need for separate light redirection components, reducing overall device complexity while achieving the light direction goal.
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 increases the amount of light reaching photo sensors, allowing for better detection of display area deterioration and correction of irregular luminance, thereby improving display quality and reducing spot occurrence.
Implementation Method 1
increases light emission towards photo sensors by diffusing light along the slope
Implementation Method 2
an opposite electrode having a reflectance less than a reflectance of the pixel electrode
Data Source
AI summary
An organic light-emitting display apparatus includes a display area including first and second pixels. A plurality of photo sensors is arranged in an outer area of the display area. The first pixel includes a first pixel electrode, an opposite electrode, and a first emission layer between the first pixel electrode and the opposite electrode. The first pixel electrode, the opposite electrode, and the first emission layer are arranged on a substrate. The second pixel includes a second pixel electrode, the opposite electrode having a reflectance less than a reflectance of the second pixel electrode, and a second emission layer between the second pixel electrode and the opposite electrode. The second pixel is closer to the plurality of photo sensors than the first pixel. The second pixel electrode includes a first portion in parallel with the substrate and a second portion having a slope with respect to the substrate.