Organic EL Lens Diameter Control for Luminance Uniformity
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Solution Overview
Problem
Display apparatuses using organic electroluminescence (EL) elements with optical interference effects face issues with luminance characteristics due to light emission at larger radiation angles, where the presence of lenses increases luminance unnaturally, leading to uneven light distribution and chromaticity deviations.
Innovation Solution
A display apparatus design incorporating an organic EL element with a specific optical distance relationship between the reflective surface and luminescent layer, combined with a lens system where the lens diameter is set to prevent light emission at angles beyond a local minimum intensity point, ensuring even luminance and reduced color drift.
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 patent applies local quality by creating a microlens array where each lens has different optical properties tailored to its position. The microlenses are arranged to selectively extract light at different angles from different regions of the organic EL element, with each lens optimized for its local light extraction needs rather than using a uniform lens design throughout.
Solution Approach 2:
The patent changes optical parameters by adjusting the focal length, curvature radius, and refractive index of the microlenses. By varying these parameters across different lens positions and designs, the system optimizes light extraction efficiency while controlling the radiation angle-dependent luminance characteristics to maintain natural appearance.
2Illumination intensity
If film thickness is set to utilize optical interference effect, then color purity and luminous efficiency are improved, but luminance changes depending on radiation angle
Solution Approach 1:
The patent introduces microlenses as intermediary optical elements between the organic EL element and the viewer. These microlenses mediate the light extraction process by controlling the radiation angles of extracted light, thereby compensating for the radiation angle-dependent luminance variations caused by the optical interference effect in the thin film structure.
Solution Approach 2:
The patent applies dynamics by making the optical system adaptive to different viewing angles through the microlens array. The microlenses dynamically control the light extraction angles based on their position and optical properties, allowing the display to maintain consistent luminance characteristics across different radiation angles while preserving the benefits of optical interference.
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 at larger radiation angles, minimizing unnatural luminance variations and color deviations, thereby enhancing display quality.
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 lens disposed on the protective layer
Data Source
AI summary
In a display apparatus including an organic EL element utilizing the optical interference effect, and a lens, a diameter of the lens is set 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.