Disk Microlens Structures for Light Extraction in Displays
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Solution Overview
Problem
Light emitting display apparatuses face issues with light extraction efficiency due to total reflection loss, waveguide loss, and surface plasmon loss, which degrade outdoor visibility and contrast ratio, and also struggle to maintain the micro cavity effect when the light emitting element is formed on a rounded or wrinkled surface.
Innovation Solution
A light emitting display apparatus with a novel structure featuring a substrate, an over coating layer, and a plurality of disk-shaped structures with a flat upper surface, a reflective layer, and a light emitting element, which improves light extraction efficiency and maintains the micro cavity effect by reducing scattering reflectance and controlling optical distance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a rounded curved surface such as a lens structure or wrinkled structure is formed to improve light extraction efficiency, then light extraction efficiency is improved, but scattering reflectance in off-state is increased so that visual sense in black is degraded and outdoor visibility and contrast ratio are degraded
Solution Approach 1:
The invention divides the surface structure into multiple discrete disk-shaped microlens structures rather than using a continuous rounded surface. Each microlens has a flat upper surface and inclined side surface, segmenting the light extraction function while maintaining control over scattering properties. This segmentation allows light extraction improvement without excessive scattering that would degrade black visual sense.
Solution Approach 2:
The invention applies different surface qualities to different regions: the upper surface of each microlens is flat to minimize scattering and maintain good black visual sense, while the side surfaces are inclined to facilitate light extraction. This local differentiation of surface quality resolves the contradiction between light extraction efficiency and visual sense in black state.
2Loss of energy
If a rounded curved surface such as a lens structure or wrinkled structure is formed to improve light extraction efficiency, then light extraction efficiency is improved, but it is difficult to control optical distance so that micro cavity effect cannot be appropriately implemented
Solution Approach 1:
By segmenting the surface into discrete microlens structures with defined geometries, the invention enables precise control of optical distance. Each microlens can be manufactured with controlled height and inclination angles, allowing the optical cavity distance to be precisely managed while still achieving improved light extraction through the structured surface.
Solution Approach 2:
The invention changes the geometric parameters of the surface structures - specifically using flat upper surfaces with controlled inclination angles on the side surfaces. This parameter control allows optimization of both light extraction efficiency and optical distance, enabling the micro cavity effect to be properly implemented while maintaining manufacturing precision.
3Illumination intensity
If the light emitting element is formed on a flat surface to improve visual sense in black and outdoor visibility, then scattering reflectance is reduced, but light extraction efficiency is degraded due to total reflection loss, waveguide loss, and surface plasmon loss
Solution Approach 1:
The invention segments the flat surface into multiple microlens structures, combining the benefits of both flat and curved surfaces. The segmented structure maintains flat upper surfaces for good visual sense in black state while introducing inclined side surfaces to reduce total reflection loss, waveguide loss, and surface plasmon loss, thereby improving light extraction efficiency.
Solution Approach 2:
The invention applies different surface qualities locally: flat upper surfaces to minimize scattering and maintain good black visual sense, and inclined side surfaces to improve light extraction by reducing various losses. This local differentiation resolves the contradiction between visual sense in black and light extraction efficiency.
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 solution enhances light extraction efficiency, improves outdoor visibility, and maintains a constant optical distance, resulting in better contrast ratio and visual sense in black, while reducing power consumption and maintaining the micro cavity effect.
Implementation Method 1
a reflective layer on the plurality of structures
Implementation Method 2
a light emitting layer, and a cathode on the light emitting layer
Data Source
AI summary
A light emitting display apparatus can include a substrate; an over coating layer disposed on the substrate; a plurality of structures on the over coating layer, each of the plurality of structures including a flat upper surface; a reflective layer disposed on the plurality of structures; and a light emitting element disposed on the plurality of structures and the reflective layer.