Organic EL Panel Aperture Ratios for Color Shift

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Solution Overview

Problem

The lifetime difference among organic electroluminescent (EL) panels emitting red, green, and blue light leads to uneven deterioration, causing color shift and reduced image quality in image light generation modules.

Innovation Solution

The image light generation module uses three organic EL panels with different pixel aperture ratios and the same pixel pitch, where the panels emit unpolarized light, and a dichroic prism combines these lights to minimize lifetime differences and color shifts by adjusting the pixel aperture ratios to ensure balanced deterioration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If three organic EL panels emitting different colors are used to generate white light, then the image light generation module can achieve full-color display capability, but the lifetime difference among the panels causes uneven deterioration and color shift

Engineering Contradiction:

Improvefull-color display capabilityVSAvoidcolor consistency

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent applies local quality by making the pixel aperture ratios different for each color panel (red, green, blue) while keeping the pixel pitch the same. This local differentiation in aperture ratios compensates for the inherent lifetime differences among the organic EL panels of different colors, ensuring that all panels deteriorate at similar rates and maintain color consistency over time.

Inventive Principle:

Principle #3Local quality

2Ease of manufacture

If the pixel aperture ratios of all panels are made equal, then the manufacturing process is simplified, but the lifetime difference among panels causes color shift and reduced image quality

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidcolor accuracy

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent changes the parameter of pixel aperture ratio differently for each color panel while maintaining the same pixel pitch. Specifically, the red panel has a first pixel aperture ratio, the green panel has a second pixel aperture ratio, and the blue panel has a third pixel aperture ratio, where these ratios are deliberately differentiated to compensate for lifetime differences and ensure uniform deterioration rates across all panels.

Inventive Principle:

Principle #35Parameter changes

3Illumination intensity

If organic EL panels with different light-emitting materials are used for different colors, then each panel can emit its specific color light effectively, but the lifetime characteristic differs for each panel

Engineering Contradiction:

Improvecolor light emission efficiencyVSAvoidpanel lifetime

Core Design Contradiction:

Illumination intensityVSDuration of action of stationary object

Solution Approach 1:

The patent applies local quality by assigning different pixel aperture ratios to panels with different light-emitting materials. Each panel's aperture ratio is specifically tailored to its material characteristics and expected lifetime, allowing the system to maintain balanced deterioration rates across all panels while preserving the effective color light emission of each material.

Inventive Principle:

Principle #3Local quality

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 approach reduces color shift and maintains image quality by ensuring all light components deteriorate at a similar rate, suppressing the white point color shift to less than 0.001, thereby providing high-quality, consistent images.

Implementation Method 1

a color combining prism configured to emit combined light obtained by combining the first image light, the second image light, and the third image light

Methodology Applied

Scientific EffectDichroic reflection: Dichroic Filter

Implementation Method 2

a first panel configured to emit first image light in a red wavelength region not having polarization characteristics, a second panel configured to emit second image light in a green wavelength region not having polarization characteristics, a third panel configured to emit third image light in a blue wavelength region not having polarization characteristics

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentUS11308869B2Image light generation module and image display device

Publication Date: 2022.04.19 SEIKO EPSON CORP

AI summary

An image light generation module according to the present disclosure includes a first panel configured to emit first image lighting a red wavelength region not having polarization characteristics, a second panel configured to emit second image light in a blue wavelength region not having polarization characteristics, a third panel configured to emit third image light in a green wavelength region not having polarization characteristics, and a color combining prism configured to emit combined light obtained by combining the first image light, the second image light, and the third image light. The first panel, the second panel, and the third panel each include a pixel structure in which a plurality of pixels are disposed, and aperture ratios of the pixels of the first panel, the second panel, and the third panel differ from each other.