Photochromic Surface Color Stability via UV Cutoff

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Solution Overview

Problem

Existing color-changing technologies using electrochromic compounds require electrical systems and cannot maintain color changes for extended periods, limiting their versatility and application in products that need long-lasting color transformations.

Innovation Solution

The method involves depositing a photochromic substance, such as diarylethene, on a surface and exposing it to specific ultraviolet wavelengths to change color, followed by applying a wavelength-cutoff agent to block ultraviolet radiation from natural light, allowing the color to be maintained for a desired time.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If electrochromic compounds are used to change the color of the surface, then the color can be controlled electrically, but the colored state only lasts for a certain time after charge removal and requires an electrical system

Engineering Contradiction:
Improveelectrical control of colorVSAvoidduration of colored state
Core Design Contradiction:
Ease of operationVSDuration of action of stationary object

Solution Approach 1:

The patent replaces the electrical control system with a photochromic compound that responds to light irradiation. Instead of using electrochromic materials requiring power supplies and electrical circuits, the invention uses organic photochromic compounds that undergo reversible color changes when exposed to specific wavelengths of light, thereby substituting the electrical control mechanism with an optical one.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the control parameter from electrical voltage/charge to light wavelength and intensity. By selecting specific wavelengths of light that match the absorption characteristics of the photochromic compound, the color change is triggered. The duration of the colored state is controlled by the intensity and duration of light exposure, as well as the molecular structure of the photochromic compound.

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If electrochromic compounds are used to change the color of the surface, then the color can be changed, but an electrical system including power supply is required

Engineering Contradiction:
Improvecolor changing capabilityVSAvoidelectrical system complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent replaces the electrical system with a photochromic compound that responds to light irradiation. Instead of using electrochromic materials requiring power supplies and electrical circuits, the invention uses organic photochromic compounds that undergo reversible color changes when exposed to specific wavelengths of light, thereby substituting the electrical control mechanism with an optical one.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The photochromic compound itself serves as both the color-changing material and the control mechanism. When exposed to light of appropriate wavelength, the compound autonomously undergoes molecular transformation to produce the desired color change, eliminating the need for external electrical control systems, power supplies, or complex circuitry.

Inventive Principle:
Principle #25Self-service

3Ease of operation

If photochromic compounds are used to change color with ultraviolet light, then the color can be changed, but the color reverts quickly under natural light containing ultraviolet

Engineering Contradiction:
Improvecolor change responseVSAvoidduration of maintained color
Core Design Contradiction:
Ease of operationVSDuration of action of stationary object

Solution Approach 1:

The patent applies a wavelength-cutoff agent to specific regions or layers to selectively block ultraviolet wavelengths while allowing visible light to pass. This creates a localized modification of the light environment, protecting the photochromic compound from UV-induced fading in specific areas while maintaining the desired color state.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The wavelength-cutoff agent acts as an intermediary between natural light and the photochromic compound. It selectively filters out ultraviolet wavelengths that cause unwanted fading while allowing visible light to reach the photochromic compound, thereby mediating the interaction to maintain the desired color state for extended periods.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 enables reversible color changes without electrical systems, maintaining the desired color for a prolonged period under natural light by using photochromic compounds that change color in response to ultraviolet light and revert with visible light, preventing fading.

Implementation Method 1

A phenomenon that a reversible transformation of a single compound between two isomers (A and B) of different colors without changing its molecular weight upon irradiation with light is known as photochromism

Methodology Applied
Scientific EffectPhotochromism: Photochromism

Implementation Method 2

wavelength-cutoff agents that can block specific wavelengths, manufactured by Fujifilm Corporation, are commercially available under the trade name 'COMFOGUARD' as specific-wavelength-cutoff agents capable of selectively cutting off specific unwanted wavelengths

Methodology Applied
Scientific EffectWavelength cutoff: Absorption (EM radiation)

Data Source

PatentEP3932246B1Color-changing method for surface section
Publication Date: 2024.04.03 KOIBUCHI MICHIO
  • EP3932246B1 patent drawingFigure 1
  • EP3932246B1 patent drawingFigure 2
  • EP3932246B1 patent drawingFigure 3

AI summary

[Technical Problem] To reversibly change the color of the surface of an object using a photochromic substance [Solution to Problem] To deposit a photochromic substance 3 on a surface-forming portion 1 of an object; and, when light in an ultraviolet range 5 is projected onto the surface of the deposited photochromic substance 3 to change the color of the photochromic substance 3 by photochromism, cover the deposited photochromic substance 3 with a wavelength-cutoff agent 4 that blocks wavelengths in an ultraviolet spectrum contained in natural light and/or illumination light.