Electrochromic Layer Diffusion Control for Color Balance

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Solution Overview

Problem

Existing organic electrochromic devices suffer from inadequate color balance due to differences in diffusion coefficients of electrochromic materials, leading to variations in light transmittance when used in imaging apparatuses and display devices.

Innovation Solution

An electrochromic device with a pair of electrodes and an electrochromic layer containing different electrochromic materials of the same polarity, where the diffusion coefficients of the materials are optimized to satisfy specific ratios, ensuring consistent color balance by controlling the diffusion process and absorbance ratios.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If different electrochromic materials with different diffusion coefficients are used in the organic electrochromic layer, then the absorption wavelengths and absorbance can be varied to achieve color display, but the color balance changes in regions where the diffusion coefficients differ significantly

Engineering Contradiction:
Improvecolor display capabilityVSAvoidcolor balance
Core Design Contradiction:
Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

The patent applies parameter changes by carefully selecting electrochromic materials whose diffusion coefficients satisfy specific mathematical relationships (Formulas 1-3). By controlling the diffusion coefficients D1, D2, D3 to meet these formulas, the patent maintains stable color balance while enabling color display functionality. This resolves the contradiction by changing the parameters (diffusion coefficients) to optimal values that satisfy both color versatility and color balance stability.

Inventive Principle:
Principle #35Parameter changes

2Stability of the object's composition

If electrochromic materials with optimized diffusion coefficients are used to maintain color balance, then the color balance stability improves, but the selection of materials becomes more constrained

Engineering Contradiction:
Improvecolor balanceVSAvoidmaterial selection flexibility
Core Design Contradiction:
Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The patent transforms the material selection constraint into a solvable parameter optimization problem. By defining specific mathematical relationships (Formulas 1-3) among diffusion coefficients, the patent provides clear selection criteria that guide material choice while ensuring color balance stability. This approach converts apparent restrictions into structured design guidelines.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent introduces diffusion coefficient ratios as intermediary parameters that mediate between material properties and color balance outcomes. By using these ratios (D1/D2, D2/D3, D1/D3) as intermediate control variables, the patent enables systematic material selection that automatically ensures color balance stability while maintaining design flexibility.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Device complexity

If the diffusion coefficients of electrochromic materials are not optimized, then the device structure and material selection remain simple, but the transmittance variation exceeds acceptable ranges in imaging applications

Engineering Contradiction:
Improvestructure simplicityVSAvoidtransmittance control precision
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The patent achieves precise transmittance control (within ±10-20%) by optimizing the diffusion coefficient parameters of electrochromic materials. The mathematical relationships (Formulas 1-3) provide a straightforward parameter selection guide that maintains structural simplicity while ensuring high manufacturing precision for imaging applications.

Inventive Principle:
Principle #35Parameter changes

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 optimized diffusion coefficients and absorbance ratios maintain stable color balance and transmittance variations within ±10% to ±20%, enhancing the performance of the electrochromic device in imaging and display applications.

Implementation Method 1

electrochromic materials of which the optical absorption properties (such as absorption wavelength and absorbance) are changed through an electrochemical redox reaction

Methodology Applied
Scientific EffectElectrochemical redox reaction: Redox Reactions

Implementation Method 2

the molecules of the electrochromic materials in the organic electrochromic layer have different diffusion coefficients

Methodology Applied
Scientific EffectDiffusion: Diffusion

Data Source

PatentEP3080660B1Electrochromic device, optical filter, lens unit, and imaging apparatus
Publication Date: 2019.03.06 CANON KK
  • EP3080660B1 patent drawingFigure 1
  • EP3080660B1 patent drawingFigure 2
  • EP3080660B1 patent drawingFigure 3

AI summary

The present invention provides an electrochromic device including a pair of electrodes and an electrochromic layer disposed between the pair of electrodes and containing different electrochromic materials having the same polarity, wherein in the case where two materials are selected from the different electrochromic materials having the same polarity in descending order of maximum absorbance in a color-display mode of the electrochromic layer and where the diffusion coefficients of the molecules of the two materials are compared with each other in the color-display mode, a smaller diffusion coefficient D2min, a larger diffusion coefficient D2max, and maximum absorbance H2 of the molecules of the electrochromic material having the diffusion coefficient D2max in the color-display mode satisfy Formula (5). 1 ≤ D2max / D2min ≤ (1 + 0.146/H2)2 (5)