Light-Emitting Device With Position-Dependent Layer Thickness
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Solution Overview
Problem
Existing display devices, such as head-mounted displays, face challenges in achieving a larger visual field angle while maintaining color accuracy, as the angle of view increases, leading to chromaticity deviation and reduced light extraction efficiency due to changes in optical path length and resonant wavelength.
Innovation Solution
The implementation of a light-emitting device with a resonance structure that includes sub-pixels with varying thicknesses of the light-emitting functional layer and adjustment layers, where the thickness of the functional layer in peripheral sub-pixels is greater than in central sub-pixels, allowing for active adjustment of the optical path length and correction of resonant wavelength offset, thereby enhancing visual field angle characteristics and suppressing chromaticity deviation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the angle of view is increased to produce a larger virtual image with a smaller display device, then the visual field angle is improved, but chromaticity deviation occurs at the peripheral edge portion due to increased optical path length and resonant wavelength shift
Solution Approach 1:
The patent applies local quality by making the light-emitting functional layer thickness position-dependent within the display region. Specifically, the thickness is increased in the peripheral area compared to the central area, creating a non-uniform thickness distribution that compensates for the optical path length differences caused by large viewing angles. This local variation in thickness maintains consistent chromaticity across different regions of the display when viewed at wide angles.
Solution Approach 2:
The patent changes the physical parameter of layer thickness to resolve the chromaticity deviation problem. By increasing the thickness of the light-emitting functional layer in peripheral sub-pixels relative to central sub-pixels, the optical path length is adjusted to compensate for the increased angle of incidence at the display edges, thereby maintaining resonant wavelength consistency and chromaticity uniformity across the entire display region.
2Use of energy by moving object
If a resonance structure is used to strengthen light of each color wavelength by interference, then light extraction efficiency is improved, but extraction efficiency decreases and chromaticity changes when the principal ray inclination increases
Solution Approach 1:
The patent applies local quality by implementing position-dependent thickness control of the light-emitting functional layer. The thickness is specifically increased in peripheral regions where the principal ray inclination is larger, while maintaining standard thickness in the central region. This localized thickness adjustment ensures that the resonance condition remains stable across different viewing angles and positions, maintaining reliable light extraction efficiency throughout the display region.
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 improves visual field angle characteristics and light extraction efficiency by actively adjusting the optical path length, ensuring consistent color accuracy even at larger angles of view, resulting in a more effective display device.
Implementation Method 1
a resonance structure in which light emitted from the light-emitting functional layer resonates between the reflection layer and the semi-transmissive reflection layer
Implementation Method 2
the resonance structure producing resonance in light emitted from the organic EL element. Specifically, by optimizing the optical path length between the reflection layer and the common electrode for each color of light, red, green, and blue, the light of each color wavelength is strengthen by interference
Data Source
AI summary
A light-emitting device includes a semi-transmissive reflection layer, a first reflection layer that is disposed in a first sub-pixel, a second reflection layer that is disposed in a second sub-pixel, the second sub-pixel that emits same color light as the first sub-pixel, and a light-emitting functional layer that is disposed between the first reflection layer and the semi-transmissive reflection layer, the light-emitting functional layer that is disposed between the second reflection layer and the semi-transmissive reflection layer. A thickness of the light-emitting functional layer in the second sub-pixel is thicker than a thickness of the light-emitting functional layer in the first sub-pixel.