Reflective Partition Light Extraction OLED Sub-Pixels
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Solution Overview
Problem
Light emitting display apparatuses suffer from low light extraction efficiency and front light extraction efficiency due to light being emitted in lateral directions rather than the front, resulting in lost light and reduced brightness.
Innovation Solution
A light emitting display apparatus with a substrate having sub-pixels that include a light emitting area and a reflective area, an overcoating layer, a partition on the reflective area, and a reflective part made of the same material as the light emitting element, which reflects light upward to improve extraction efficiency and brightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If light emitting elements emit light in all directions, then the light output is maximized, but the front light extraction efficiency is reduced due to lateral light loss
Solution Approach 1:
The pixel structure is segmented into distinct functional zones: a light emitting area where organic light emitting elements are positioned, and a reflective area surrounding it. This segmentation allows light to be directed differently in different zones, with the reflective area capturing lateral light and redirecting it upward to improve front extraction efficiency without requiring complex additional components.
Solution Approach 2:
The reflective area extends laterally beyond the light emitting area in the horizontal plane, creating a three-dimensional light management structure. By positioning the reflective area in the lateral dimension and using partitions to define boundaries, the patent redirects light that would otherwise travel laterally into the vertical dimension, improving front extraction efficiency through spatial dimensionality rather than complex optical components.
2Loss of energy
If the reflective area is enlarged to improve light extraction, then more lateral light is redirected, but the light emitting area is reduced
Solution Approach 1:
Different areas of the pixel are assigned different functional qualities: the central light emitting area is optimized for light generation, while the surrounding reflective area is optimized for light redirection. This local differentiation allows each zone to perform its specific function efficiently, with the reflective area's lateral extension specifically targeted at capturing and redirecting lateral light without interfering with the light emitting area's primary function.
Solution Approach 2:
The reflective area acts as an intermediary structure between the light emitting elements and the external environment. Instead of directly increasing the light emitting area, the reflective area serves as a mediating zone that captures lateral light and redirects it upward, effectively increasing front extraction efficiency through an intermediate light management layer rather than expanding the light generating region.
3Loss of energy
If partitions are added to define the reflective area, then light direction is improved, but the manufacturing process becomes more complex
Solution Approach 1:
The partition structure is merged with the pixel electrode and overcoating layer, integrating the light management function into existing structural elements. Rather than adding separate partition components, the patent combines the partition function with the electrode and coating layers, allowing light redirection to be achieved through integrated structuring of already-present layers, thereby reducing manufacturing complexity while maintaining light extraction efficiency.
Solution Approach 2:
The overcoating layer serves multiple functions: it provides structural coverage, defines pixel boundaries, and when structured with lateral extensions, creates the reflective area and partition structures. This multi-functionality allows a single layer to perform both protective/structural roles and light management roles, eliminating the need for separate partition components and simplifying the manufacturing process.
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
Enhances the utilization of light emitted from the light emitting element, improving light extraction efficiency and front light extraction efficiency, thereby increasing the brightness and viewing angle of the display apparatus.
Implementation Method 1
a reflective part on the partition and formed of a same material as the light emitting element... some of light emitted from the light emitting element is reflected upwardly of the light emitting element by the reflective part
Data Source
AI summary
A light emitting display apparatus includes a substrate including a plurality of sub-pixels, each of the plurality of sub-pixels including a light emitting area and a reflective area surrounded by the light emitting area, an overcoating layer on the substrate, a partition at the reflective area on the overcoating layer, a light emitting element at the light emitting area on the overcoating layer, and a reflective part on the partition and formed of a same material as the light emitting element.