Asymmetric Parabolic Reflector for OLED Luminance Optimization
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Solution Overview
Problem
Light emitting devices, such as OLEDs and LEDs, face inefficiencies in light extraction, leading to suboptimal luminance and increased power consumption, especially when viewed at angles beyond 70°, as existing solutions like compound parabolic concentrators (CPCs) overemphasize high-angle light distribution rather than enhancing luminance within the effective visual range.
Innovation Solution
A light emitting device with a concave mirror portion having a light reflecting surface formed by rotating a part of a parabola, where the central axis of rotation is set to pass through the side of the parabola with respect to the middle point of a line segment joining the parabola and its focal point, allowing controlled light distribution to enhance luminance within the effective visual range while maintaining uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a compound parabolic concentrator (CPC) structure is used to enhance light extraction, then light extraction efficiency is improved, but luminance within the effective visual range (low-angle region) deteriorates because high-angle light distribution is overemphasized
Solution Approach 1:
The patent applies asymmetry by offsetting the central axis of the parabola from the normal line of the emission surface. The offset distance is specifically designed to be between 0.05mm and 0.15mm, creating an asymmetric optical path that redirects high-angle light components toward lower angles within the effective visual range while maintaining the light-trapping benefits of the CPC structure
Solution Approach 2:
The patent implements local quality by creating region-specific light distribution characteristics. The offset parabola structure selectively redirects light in different angular regions: high-angle light (beyond 70°) is redirected to intermediate angles, while intermediate-angle light is directed toward the front viewing zone, optimizing luminance distribution for different viewing regions
2Ease of manufacture
If a conventional parabolic reflector with central axis along the normal line is used, then manufacturing is simplified, but light distribution uniformity within the effective visual range deteriorates
Solution Approach 1:
The patent deliberately introduces asymmetry by offsetting the parabola's central axis from the normal line. This controlled asymmetry creates a specific light redistribution pattern that achieves uniform luminance across the effective visual range (viewing angles up to 60°), while the offset distance is constrained to maintain manufacturability
3Illumination intensity
If the offset distance of the parabola central axis is too large, then luminance enhancement is improved, but light extraction efficiency deteriorates due to excessive redirection of light away from the emission surface
Solution Approach 1:
The patent optimizes the offset distance parameter within a specific range of 0.05mm to 0.15mm. This parameter optimization balances two competing effects: sufficient offset to redirect high-angle light to improve luminance, but not so much offset that light extraction efficiency deteriorates. The focal length is simultaneously optimized at 0.5mm to 1.5mm to maintain the parabola's light-trapping capability
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 suppresses high-angle light distribution components, increasing low-angle components, thereby enhancing luminance and reducing power consumption by optimizing light distribution angles, resulting in brighter and more energy-efficient displays.
Implementation Method 1
a concave mirror portion (38) configured to reflect a light emitted from the light emitting element (45)
Implementation Method 2
the concave mirror portion (38) has a light reflecting surface (38a) obtained by rotating a part of a parabola
Data Source
AI summary
Disclosed herein is a light emitting device, which includes a light emitting element configured to emit a light, and a concave mirror portion configured to reflect the light emitted from the light emitting element, the concave mirror portion being erected on a circumference of an emission surface of the light emitting element. The concave mirror portion has a light reflecting surface obtained by rotating a part of a parabola. A central axis of the rotation is set in a position of passing through a side of the parabola with respect to a middle point of a line segment joining the part of the parabola and a focal point of the parabola.