OLED Color Shift Compensation via Phase Retardation Layers
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Solution Overview
Problem
Organic light-emitting display devices experience color shift at side-view angles due to total internal reflection, reducing luminous efficiency and viewing angle, despite efforts to improve luminous efficiency with resonance structures like distributed Bragg reflectors.
Innovation Solution
Incorporating a phase retardation layer, such as a single quarter wave plate or a combination of quarter and half wave plates, between the organic light-emitting device and the first polarization plate, along with an optical compensation member like A-plates, C-plates, or biaxial plates, to adjust the phase retardation values and prevent external light reflection, thereby compensating for color shift at side-view angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a distributed Bragg reflector or adjusted organic layer thickness is used to improve luminous efficiency, then luminous efficiency is improved, but color shift occurs at side-view angles
Solution Approach 1:
The patent introduces a phase retardation layer as an intermediary component between the organic light-emitting layer and the external environment. This layer mediates the optical path of emitted light, compensating for phase differences that cause color shift at side-view angles while preserving the luminous efficiency improvements achieved through the distributed Bragg reflector or adjusted layer thickness.
Solution Approach 2:
The patent changes the optical parameters of the display structure by introducing a phase retardation layer with specific retardation characteristics. By controlling the phase retardation value (e.g., quarter-wave or half-wave retardation), the patent modifies the optical path difference for obliquely emitted light, thereby compensating for color shift without affecting the luminous efficiency parameter.
2Adaptability or versatility
If light is emitted in a wide range of wavelengths to increase viewing angle, then viewing angle is improved, but luminous efficiency and color purity are reduced
Solution Approach 1:
The patent applies local quality by making the phase retardation effect wavelength-dependent. The phase retardation layer is designed to provide specific retardation for different wavelengths, allowing the display to maintain wide viewing angle while compensating for color shift in a wavelength-specific manner, thereby preserving luminous efficiency and color purity for each wavelength component.
3Adaptability or versatility
If photons are emitted in all directions to achieve wide viewing angle, then viewing angle is improved, but extraction efficiency is reduced due to total internal reflection
Solution Approach 1:
The patent addresses the extraction efficiency problem by introducing a phase retardation layer that operates in the optical phase dimension. This layer modifies the phase relationship of obliquely emitted photons, enabling them to escape total internal reflection conditions and be extracted more efficiently, thereby reducing energy loss while maintaining wide viewing angle.
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 effectively reduces color shift at side-view angles, enhancing the viewing angle and maintaining luminous efficiency by adjusting the phase retardation values and preventing external light reflection, resulting in improved color consistency across different viewing positions.
Implementation Method 1
a phase retardation layer, such as a single quarter wave plate or a combination of quarter and half wave plates, between the organic light-emitting device and the first polarization plate
Implementation Method 2
an optical compensation member like A-plates, C-plates, or biaxial plates, to adjust the phase retardation values
Implementation Method 3
electrons and holes are combined in an organic light emission layer disposed between the anode and the cathode so that excitons are formed therein and emit light
Implementation Method 4
many photons from among photons emitted in a direction do not reach a viewer due to total internal reflection
Data Source
Figure 1
Figure 2(a)~2(c)
Figure 3~4
AI summary
An organic light-emitting display apparatus includes an organic light-emitting device (1) including a pixel electrode (20), an opposite electrode (40) facing the pixel electrode, and an organic light-emitting layer (30) interposed between the pixel electrode and the opposite electrode; a first polarization plate (70) disposed on a surface of the organic light-emitting device, the organic light-emitting device being configured to emit light through the first polarization plate; a second polarization plate (90) facing the first polarization plate; and an optical compensation member (80) between the first polarization plate (70) and the second polarization plate (90).