Stacked Light-Emitting Pixel Structure for Smaller Display Sub-Pixels
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Solution Overview
Problem
Existing display devices face challenges in reducing sub-pixel area, improving light extraction efficiency, and enhancing viewing angle and brightness properties, particularly in both forward and lateral directions.
Innovation Solution
A display device design where a first light-emitting element and a second light-emitting element are vertically stacked, with a first connection electrode made of high reflection efficiency material formed between them to improve light extraction and alignment, and additional features such as opening portions in the connection electrode and a multilayer structure with transparent and opaque electrode layers to enhance light propagation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If light-emitting elements are arranged horizontally, then alignment is straightforward, but sub-pixel area increases
Solution Approach 1:
The patent transitions from horizontal arrangement to vertical stacking of light-emitting elements, changing the spatial dimension from 2D plane to 3D vertical arrangement. This dimensional change reduces the horizontal footprint and sub-pixel area while maintaining the necessary alignment through vertical positioning rather than horizontal placement.
2Loss of energy
If connection electrode material has low reflection efficiency, then manufacturing is simpler, but light extraction efficiency decreases
Solution Approach 1:
The patent changes the material parameter of the connection electrode from low reflection efficiency materials to high reflection efficiency materials. This parameter change in material properties directly improves light extraction efficiency by reflecting more light that would otherwise be lost, while the manufacturing process remains compatible with existing techniques.
3Area of stationary object
If light-emitting elements are vertically stacked, then sub-pixel area is reduced, but alignment precision requirements increase
Solution Approach 1:
The patent implements preliminary alignment actions during the manufacturing process, where the vertical stacking of light-emitting elements is pre-positioned and secured before final assembly. This preliminary action ensures precise alignment is achieved during fabrication, reducing the need for post-manufacturing adjustments and maintaining high precision requirements.
4Adaptability or versatility
If viewing angle properties are improved, then display quality increases, but brightness in forward direction may decrease
Solution Approach 1:
The patent applies local quality enhancement by adding light-scattering particles at specific locations around the light-emitting elements. These particles are strategically positioned to scatter light in lateral directions to improve viewing angle, while the forward direction brightness is maintained through controlled scattering that does not block the primary light path.
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 vertical stacking of light-emitting elements reduces sub-pixel area, facilitates easy alignment, and improves light extraction and brightness, especially in forward and lateral directions, resulting in enhanced display quality and resolution.
Implementation Method 1
a first connection electrode, which is made of a material with high reflection efficiency, is formed between a first light-emitting element and a second light-emitting element to improve light extraction efficiency
Implementation Method 2
a plurality of light-scattering particles is formed around a first light-emitting element to allow light, which is trapped in the display device, to easily exit toward the outside of the display device, thereby improving luminous efficiency and brightness
Data Source
AI summary
One aspect of the present disclosure provides a display device including: a display panel including a plurality of sub pixels; a reflective electrode disposed in each of the plurality of sub pixels; a first light-emitting element disposed on the reflective electrode; a first connection electrode disposed on the first light-emitting element and configured such that at least a part of the first connection electrode covers the first light-emitting element; and a second light-emitting element disposed on the first connection electrode and configured to overlap the first light-emitting element, in which the first light-emitting element has a larger size than the second light-emitting element. Therefore, the first light-emitting element has a relatively large size, such that the second light-emitting element may be more easily aligned and disposed on the first light-emitting element.