Optical Film Groove Pattern for OLED Color Shift Reduction
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Solution Overview
Problem
Organic light-emitting diode (OLED) displays experience color shift issues due to the microcavity structure's wavelength amplification, which changes as the viewing angle is tilted, leading to reduced color purity and brightness.
Innovation Solution
An optical film with a high refractive index pattern layer and a low refractive index pattern layer, featuring grooves with a curved surface and a specific aspect ratio, is applied to the OLED display. The optical film includes a filling material like air or resin and can contain light diffusers or absorbers, reducing color shift by diffusing and absorbing light effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a microcavity structure is used to increase light intensity and improve color purity, then brightness and color purity are improved, but color shift occurs when viewing angle is tilted
Solution Approach 1:
The optical film is segmented into multiple functional layers: a high refractive index pattern layer with grooves for light diffusion, a low refractive index pattern layer for complementary optical effects, and additional layers for polarization and anti-reflection. This segmentation allows each layer to address specific optical issues independently, resolving the color shift problem while maintaining brightness enhancement.
Solution Approach 2:
The high refractive index pattern layer features grooves with specific aspect ratios (greater than 1 and smaller than 3) and curved surfaces that create localized light diffusion zones. These localized structural variations enable selective light manipulation at different angles, reducing color shift while preserving the microcavity's brightness enhancement function.
2Manufacturing precision
If the thickness of organic deposition material layer is designed for wavelength resonance, then color purity is improved, but the light path length changes at lateral sides causing wavelength shift
Solution Approach 1:
The optical film acts as an intermediary layer between the microcavity structure and the viewer. The high refractive index pattern layer with its groove structure diffuses light in a way that compensates for the path length variations occurring at lateral viewing angles, thereby maintaining consistent wavelength resonance effects across different viewing angles.
Solution Approach 2:
The invention addresses the two-dimensional viewing angle problem by introducing a vertically structured optical film with layered architecture. The grooves extend in the vertical dimension with controlled aspect ratios, creating three-dimensional light diffusion paths that compensate for lateral viewing angle effects and maintain wavelength consistency.
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 optical film significantly reduces color shift and maintains brightness across various viewing angles, improving color purity and visibility by diffusing and absorbing light, thereby enhancing the display's performance.
Implementation Method 1
The lens section has a plurality of engraved or raised patterns spaced apart from each other to diffuse incident light
Implementation Method 2
The filling material may include a transparent plastic material including a light diffuser or a light absorber
Implementation Method 3
the microcavity structure is a structure in which distances between anodes and cathodes are designed to respectively correspond to representative wavelengths of red (R), green (G), and blue (B), so that only light of wavelengths corresponding thereto resonate and are emitted
Implementation Method 4
An optical film includes a high refractive index pattern layer and a low refractive index pattern layer
Data Source
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AI summary
Optical films, and organic light-emitting display apparatuses employing the same, include a high refractive index pattern layer (110) including a first surface and a second surface facing each other, wherein the first surface includes a pattern having a plurality of grooves (GR). The plurality of grooves each have a curved surface and a depth greater than a width thereof. The high refractive index pattern layer is formed of a material having a refractive index greater than 1. The optical films, and the organic light-emitting display apparatuses, further include a low refractive index pattern layer (120) formed of a material having a refractive index smaller than the refractive index of the material constituting the high refractive index pattern layer. The low refractive index pattern layer includes a filling material for filling the plurality of grooves.