RGB Light Emitting Structure for Wide-Angle Color Shift Control

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Solution Overview

Problem

Existing light emitting devices experience significant color shift issues at wide viewing angles due to the interaction of light extraction structures with optical resonant structures, leading to reduced light extraction efficiency and increased power consumption.

Innovation Solution

The implementation of a light emitting device design where the resonant peak wavelength in the normal direction of the substrate is set larger than the peak wavelength of the emission spectrum for green and blue light emitting elements, with a specific difference between these wavelengths to shift color shifts towards the blue side, thereby reducing the visibility of color shifts at wide angles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If a light extraction structure such as a microlens is provided to improve light extraction efficiency, then power consumption is reduced, but color mixture with adjacent light emitting elements occurs and optical conditions change causing increased color shift at wide viewing angles

Engineering Contradiction:
Improvepower consumptionVSAvoidcolor shift
Core Design Contradiction:
Use of energy by moving objectVSObject-affected harmful factors

Solution Approach 1:

The patent applies different resonant wavelength configurations to different color light emitting elements (red, green, blue) locally. Each element is designed with a resonant structure optimized for its specific wavelength, allowing the light extraction structure to work effectively for each color while minimizing color shift at wide viewing angles through localized optical condition control

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent changes the resonant wavelength parameter of the optical resonant structure to match the peak emission wavelength of each light emitting element. By adjusting this critical parameter, the system achieves improved light extraction efficiency and reduced color shift simultaneously, resolving the contradiction between energy efficiency and color stability

Inventive Principle:
Principle #35Parameter changes

2Productivity

If the resonant wavelength is configured to match the peak emission wavelength of each light emitting element, then light extraction efficiency is improved, but the relationship between resonant wavelength and color shift changes causing visibility issues at wide angles

Engineering Contradiction:
Improvelight extraction efficiencyVSAvoidcolor shift visibility
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent implements local quality optimization by configuring each light emitting element's resonant structure with a resonant wavelength specifically matched to its peak emission wavelength. This localized tuning allows high light extraction efficiency for each element while the overall arrangement minimizes color shift visibility through controlled optical interactions between adjacent elements

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 design effectively minimizes the visibility of color shifts at wide viewing angles by adjusting the resonant peak wavelengths of green and blue light emitting elements, enhancing light extraction efficiency and reducing power consumption.

Implementation Method 1

a light emitting element which includes an organic layer including a light emitting layer and a light extraction structure arranged so as to cover the light emitting layer

Methodology Applied
Scientific EffectOptical resonance: Resonance

Implementation Method 2

color mixture with an adjacent light emitting element and optical conditions such as a total reflection condition change due to the light extraction structure

Methodology Applied
Scientific EffectTotal internal reflection: Total Internal Reflection

Data Source

PatentEP4475652A1Light emitting device, display device, photoelectric conversion device, electronic apparatus, and wearable device
Publication Date: 2024.12.11 CANON KK
  • EP4475652A1 patent drawingFigure 1A~1B
  • EP4475652A1 patent drawingFigure 2A~2B
  • EP4475652A1 patent drawingFigure 3A~3D

AI summary

A light emitting device (100) in which light emitting elements (103), each of which comprises a light extraction structure (104) arranged to cover a light emitting layer, are arranged, and the light emitting elements (103) include a red light emitting element (103r), a green light emitting element (103g), and a blue light emitting element (103b), and comprise a resonant structure corresponding to each light emission color. If λon_g is a resonant peak wavelength in the resonant structure of the green light emitting element (103g), λg is a peak wavelength of the green light emitting element (103g), λon_b is a resonant peak wavelength in the resonant structure of the blue light emitting element (103b), and λb is a peak wavelength the blue light emitting element (103b), Δg = λon_g - λg > 0, Δb = λon_b - λb > 0, and Δg - Δb ≥ 0 are satisfied.