Organic EL Display Light Absorbing Layer for Luminance Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Display apparatuses using organic electroluminescence (EL) elements with optical interference effects and lenses suffer from unnatural luminance characteristics due to increased luminance at larger radiation angles, leading to uneven light distribution and chromaticity deviations when light is emitted at angles beyond a certain threshold.
Innovation Solution
A display apparatus design that includes an organic EL element with a specific optical distance relationship between the reflective surface and luminescent layer, combined with a lens and a light absorbing layer, where the light absorbing layer is positioned to prevent light emitted at larger angles from being output, ensuring a consistent luminance characteristic.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a lens is added to take out light emitted at larger radiation angles, then light extraction efficiency is improved, but luminance characteristic becomes unnatural due to increased luminance at larger angles
Solution Approach 1:
The light absorbing layer is selectively positioned to absorb light at larger radiation angles while allowing light at smaller angles to pass through. This creates a spatially differentiated optical property where different regions of the light output are treated differently based on their radiation angle, thereby improving light extraction efficiency for useful angles while preventing unnatural luminance increase at large angles.
Solution Approach 2:
The light absorbing layer acts as an intermediary element between the organic EL element and the lens. It selectively absorbs light at larger radiation angles before the light reaches the lens, preventing these angles from contributing to unnatural luminance characteristics while allowing the lens to effectively extract and direct light at optimal angles.
2Power
If optical interference effect is utilized to improve color purity and luminous efficiency, then luminous efficiency is improved, but luminance changes depending on radiation angle
Solution Approach 1:
The light absorbing layer is strategically positioned to address the radiation angle-dependent luminance variation caused by optical interference. By absorbing light at larger angles where luminance variation occurs and allowing light at optimal angles to pass through, the system maintains the benefits of optical interference (high luminous efficiency) while achieving more uniform luminance characteristics.
3Illumination intensity
If light absorbing layer is used to block light at larger angles, then luminance characteristic is improved, but light extraction efficiency may be reduced
Solution Approach 1:
The light absorbing layer is positioned and dimensioned to create a selective filtering effect. It absorbs light at larger radiation angles that cause unnatural luminance characteristics while allowing light at smaller, more useful angles to pass through to the lens. This localized absorption approach maintains high light extraction efficiency for beneficial angles while eliminating problematic large-angle light.
Solution Approach 2:
The light absorbing layer converts potentially harmful light at large angles (which causes unnatural luminance) into beneficial effects by selective absorption. This prevents the harmful luminance characteristic while the lens continues to effectively extract and direct the useful light at optimal angles, thereby converting a potential loss into an overall system benefit.
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 achieves a good luminance characteristic by controlling light output based on radiation angles, reducing color drift and maintaining consistent luminance across different viewing angles, thereby enhancing the display's overall performance.
Implementation Method 1
it is known that color purity and luminous efficiency of a luminescent color are improved by utilizing the optical interference effect
Implementation Method 2
a light absorbing layer is disposed such that, of the light radiated into the protective layer, light radiated at a larger angle than an angle, at which the light intensity distribution takes the local minimum value, is not output
Implementation Method 3
a lens array including lenses and banks serving as light absorbing layers is disposed on an organic EL element
Data Source
AI summary
In a display apparatus including an organic EL element utilizing the optical interference effect, and a lens, a light absorbing layer is disposed such that, of light radiated from the organic EL element into a protective layer, light radiated at a larger angle than an angle, at which a light intensity distribution of the light radiated into the protective layer with respect to a radiation angle of the light takes a local minimum value, is not output to the outside of the display apparatus through the lens.