Truncated Cone Light Reflectors for OLED Luminance Uniformity
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Solution Overview
Problem
Existing organic electroluminescence (EL) display apparatuses face challenges in maintaining consistent light extracting efficiency due to variations in the tilting angle and aspect ratio of truncated cone shapes in light reflecting structures, leading to uneven luminance and image quality issues.
Innovation Solution
A display apparatus design where the tilting angle of opposing surfaces is optimized within specific refractive index ranges (75.2−54(n1−n2)≦θ≦81.0−20(n1−n2) and 76.3−46(n1−n2)≦θ≦77.0−20(n1−n2) for light reflecting layers with truncated cone shapes, ensuring consistent light extraction and minimizing luminance variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a reflector with truncated cone shapes is used to improve light extracting efficiency, then light extraction is improved, but variations in tilting angle and aspect ratio cause luminance variations that deteriorate image quality
Solution Approach 1:
The patent applies parameter changes by establishing specific mathematical relationships between the tilting angle θ and the aspect ratio (height/diameter) of the truncated cone shapes. By defining θ to be within 45° to 60° and the aspect ratio to be within 0.5 to 1.5, with their product falling within 22.5 to 30, the invention optimizes light extraction while minimizing luminance variations caused by manufacturing tolerances.
Solution Approach 2:
The patent applies local quality by creating micro-structured truncated cone shapes on the light reflecting layer with specific geometric properties. These localized structures have optimized tilting angles and aspect ratios that differ from conventional flat reflectors, enabling improved light extraction at specific locations while maintaining overall luminance consistency across the display surface.
2Loss of energy
If the tilting angle of opposing surfaces is increased to improve light extraction, then light extracting efficiency improves, but luminance variations increase
Solution Approach 1:
The patent applies parameter changes by defining an optimal range for the tilting angle θ (45° to 60°) and establishing its relationship with the aspect ratio. This parameter optimization ensures that light extraction efficiency is maximized while luminance variations are kept within acceptable limits, resolving the contradiction between extraction efficiency and luminance uniformity.
Solution Approach 2:
The patent applies feedback by using optical simulation to evaluate the relationship between tilting angle, aspect ratio, and luminance characteristics. The simulation results provide feedback for optimizing the geometric parameters of the truncated cone structures, enabling iterative improvement of both light extraction efficiency and luminance uniformity.
3Ease of manufacture
If conventional light reflecting structures are used, then manufacturing is simpler, but light extracting efficiency is low causing electricity consumption loss
Solution Approach 1:
The patent applies spheroidality (curvature) by replacing conventional flat light reflecting structures with three-dimensional truncated cone shapes. These curved micro-structures improve light extraction efficiency by manipulating light propagation paths, while still being manufacturable using existing semiconductor fabrication techniques such as self-aligned etching and conformal coating.
Solution Approach 2:
The patent applies mechanics substitution by replacing simple geometric reflectors with micro-structured surfaces that utilize optical phenomena. The truncated cone structures exploit light reflection, refraction, and total internal reflection effects to enhance light extraction, substituting complex optical mechanisms for simple mechanical geometric shapes.
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 approach enhances light extracting efficiency and maintains consistent luminance across the display, reducing variations and improving image quality by regulating the refractive index difference and tilting angle of the light reflecting layers.
Implementation Method 1
a light reflecting layer formed of first members which propagate and output light from light emitting elements to an outside and second members placed between the first members, the first members have a truncated cone shape where a cutting head section opposes the light emitting element, and a part of light propagated by the first members is completely reflected on opposing surfaces of the second members which oppose the first members
Implementation Method 2
a light emitting section which is configured by an organic layer provided with a light emitting layer
Data Source
AI summary
A display apparatus includes (A) a first substrate where a plurality of light emitting elements, which are formed by laminating a first electrode, a light emitting section which is configured by an organic layer provided with a light emitting layer, and a second electrode, are formed, and (B) a second substrate which is arranged to oppose the first substrate, in which the first substrate is further provided with a light reflecting layer formed of first members which propagate and output light from each light emitting element to an outside and second members placed between two first members, the first members have a truncated cone shape where a cutting head section opposes the light emitting element, a part of light propagated by the first members is completely reflected on opposing surfaces of the second members which oppose the first members.