Inkless Printing Using Visible Light for Color Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Traditional inkless printing methods using NIR or UV radiation for color change can lead to instability under ambient light, accidental activation of inactive regions, and uneven energy distribution, resulting in non-uniform color changes and potential damage to substrates.
Innovation Solution
A method utilizing a high power density beam of visible electromagnetic radiation to effect color changes in substrates with color-forming materials like diacetylenes, ensuring stability under ambient light and reducing accidental activation, by using radiation that is directly absorbed by the color-forming material, thereby controlling the color transformation process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If NIR radiation is used to heat the coating layer for color change, then color transformation efficiency is improved, but substrate damage and decomposition occur due to excessive heat transfer to surrounding materials
Solution Approach 1:
The patent changes the wavelength parameter of the radiation from NIR to visible range (400-700 nm), which is directly absorbed by the diacetylene color former without requiring thermal conversion. This parameter change enables direct photochemical activation while avoiding the thermal damage caused by NIR heating of surrounding materials.
Solution Approach 2:
The patent replaces the thermal mechanism (NIR heating through absorber) with a direct optical mechanism (visible light absorption by diacetylene). This substitution eliminates the intermediate thermal conversion step that causes heat transfer to surrounding materials and substrate damage.
2Reliability
If UV radiation is used to effect color change, then color transformation can be achieved, but energy consumption increases and some colors require impractically high temperatures
Solution Approach 1:
The patent changes the radiation wavelength from UV to visible range, matching the absorption spectrum of the diacetylene color former. This parameter optimization enables efficient color transformation at moderate temperatures, avoiding the excessive energy requirements of UV while preventing the impractically high temperatures needed for certain colors.
3Illumination intensity
If the incident radiation has a non-uniform intensity distribution, then different regions receive different energy quantities, but this results in non-uniform color changes and multi-color spots
Solution Approach 1:
The patent utilizes the self-absorbing property of the diacetylene color former in the visible range. The material itself serves as the absorbing agent, and its absorption characteristics naturally limit the penetration depth and distribute energy uniformly throughout the coating layer, compensating for non-uniform incident radiation intensity and producing uniform color changes.
4Adaptability or versatility
If NIR absorber is added to make the coating sensitive to NIR radiation, then color transformation becomes possible, but accidental activation of inactive color forming material occurs, affecting long-term light stability
Solution Approach 1:
The patent extracts and eliminates the NIR absorber component from the coating formulation. By removing this intermediate thermal conversion agent, the system directly uses visible light absorption by diacetylene, preventing accidental activation of inactive color forming material and preserving long-term light stability.
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 allows for precise and efficient color changes with reduced energy requirements, minimizing substrate damage and maintaining long-term light stability, even with non-uniform radiation intensity distributions, by using visible radiation that is self-terminating once a target color is reached.
Implementation Method 1
using radiation that is directly absorbed by the color-forming material
Implementation Method 2
a high energy density beam of visible radiation is used to effect a colour change
Implementation Method 3
The NIR absorber absorbs NIR radiation from the laser and transfers this energy, as heat, not only to the diacetylene coloured material but also to surrounding material such as binders and substrate
Data Source
AI summary
The present invention relates to a method of marking a substrate that comprises a color forming material, comprising the steps of: activating a region of the substrate so as to transform it from an inactive, low reactive state to an active, high reactive state; irradiating a part of the activated region with an initial color changing radiation to effect an initial color change to a first color; and irradiating a part of the substrate that has been changed to the first color with a high power density beam of visible electromagnetic radiation to effect a further color change of the irradiated region to a second color.