Curved Color Filter for Organic EL Display Angle-Dependent Chromaticity
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Solution Overview
Problem
Organic EL display devices with a color filter experience changes in chromaticity and brightness when viewed from different angles due to the curvature of the organic EL layer, causing light emitted obliquely to travel a longer distance through the color filter compared to light emitted perpendicular to the device.
Innovation Solution
A display device configuration featuring a curved organic EL layer and a matching curved color filter, with the color filter either on the second substrate or the first substrate, and an insulating layer with concave portions to reduce the distance between the organic EL layer and the color filter, preventing light mixing between pixels and minimizing angle-dependent chromaticity and brightness changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the organic EL layer is curved to emit light in oblique directions, then light emission in multiple directions is improved, but the distance light travels through the color filter increases causing chromaticity and brightness changes
Solution Approach 1:
The color filter is formed with a curved surface that matches the curvature of the organic EL layer. This curvature compensation ensures that light traveling at oblique angles passes through a consistent effective thickness of the color filter, maintaining uniform chromaticity and brightness across different viewing angles while preserving the broad light emission pattern
Solution Approach 2:
The patent changes the geometric parameter of the color filter from flat to curved, matching the curvature radius to that of the organic EL layer. This parameter adjustment compensates for the increased optical path length in oblique directions, maintaining consistent light transmission characteristics across different emission angles
2Object-affected harmful factors
If the color filter is formed on the second substrate side, then protection of the organic EL layer is improved, but the distance between the organic EL layer and color filter increases causing greater chromaticity changes
Solution Approach 1:
The color filter is formed with a curved surface on the second substrate side that precisely matches the curvature of the organic EL layer. This curvature matching ensures that even with the increased distance, the effective thickness of the color filter remains consistent for light at different angles, maintaining chromaticity uniformity while providing protection to the organic EL layer
3Illumination intensity
If the organic EL layer is curved to swell the light emitting surface, then light emission in oblique directions is improved, but light from adjacent pixels mixes together
Solution Approach 1:
The organic EL layer is curved to form a concave shape with the light emitting surface facing outward. This concave curvature configuration, combined with the matching curved color filter, directs oblique light emission while maintaining spatial separation between adjacent pixels, preventing light mixing while enabling broad viewing angles
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 configuration effectively stabilizes chromaticity and brightness across viewing angles by reducing the distance light travels through the color filter and preventing light mixing between pixels, enhancing light emission efficiency and reducing angle-dependent variations.
Implementation Method 1
an organic EL layer having a curved portion curved in a cross-sectional view, which is disposed in at least one of the plurality of pixels
Implementation Method 2
a color filter having a curved portion curved to match the curved portion of the organic EL layer
Data Source
AI summary
A display device includes a first substrate, an organic EL layer formed on the first substrate and curved in each pixel, and color filters disposed in the respective pixels, and curved to match the organic EL layer. With this configuration, a change in the chromaticity and brightness of the display device depending on a viewing angle of a user is reduced.