Color change and jump light
First of all, we need to introduce the tri-excitation value. This term is related to color change (light jump).
Tristimulus Values
The color appears on the surface of the object illuminated by light because the light is projected inside , part is absorbed by the object, and part is reflected at the same time; the visible spectrum of the eye is from 400 μm wavelength to 750 μm wavelength. Human beings use each reflected wavelength to feel different intensities. In the structure of the human visual system, there are three Different stimulation centers can resolve the intensity of this wavelength and sense three stimulations such as red, green, and blue respectively, and then send them to the stimulation brain to combine them into colors; these three stimulations are called Tristimulus Values.
Metamerism (jumping lights)
What is metamerism? (Light jump):
Although the two color “standard samples” and “comparison samples” may be consistent under a specific light source, they become incompatible under other light sources. , this is called color change, and these two colors are called “color change pairs”. The reason and explanation for its occurrence are:
The physical explanation is that there is a pair of colors with different spectra. But if it is the same under a certain light source, this pair of colors is called “metamerism”. Of course, it will be different if it is changed to other light sources. To explain further, under a specific light source (we call it the first light source), the triexcitation values of the standard sample and the comparison sample are adjusted to the same, so the two colors look the same, but under another light source (we call it the second light source) Light source) The triple excitation values of the standard sample and the comparison sample are not necessarily the same. The reason for this is that the intensity of each wavelength of the second light source from 400 μm to 750 μm in the wavelength spectrum is inconsistent with the original first light source, so it is reflected on the color sample. The intensity of light will be different, and the triexcitation values will be different if the intensity is different. If the triexcitation values are different, the color feeling combined by the brain will not be as consistent as the first light source.
Why do different types of dyes change color seriously?
Dye (pigment) structure
The dye structure is basically divided into three parts: “color root group” and “reaction ( Combine) root group” “Connect root group”
Chromogenic root group: Light (photons) can be irradiated onto this chemical structure (photons hit the chromogenic root group, causing resonance and emitting a specific wavelength ) has a sense of color.
Reaction (binding) root group: It can react with fibers to fix the dye. This is called the reaction root group of the dye. Different types of fibers have different reaction combination groups. For example, cotton, or nylon/or nylon dyes have different reaction groups in them.
Connect the root group: it is between the chromogenic root group and the reaction root group, to bridge and connect the chromogenic root group and the reaction root group, so that the chromogenic root group and the reaction root group The reaction roots become one.
Why do the colors dyed with similar dyes have smaller color jumps (color changes)? Non-similar dyes produce larger colors.
1). Numerous products have been developed for any type of dyes, but not many of them are suitable for the commercial market. If they are suitable for commercialization, global dye companies are competing to imitate them, and some are trying to avoid them. The patent only slightly changes the chemical structure of the dye, so the wavelength spectrum of the dye is very close.
2). There is little difference in technology between dyeing and finishing factories, and the dyes used are an open secret: the dyes used in dyeing factories are almost the same.
●This is why there is little color change when using the same type of dyes.
For example: the customer who dyes cotton gives the standard color sample of cotton, and the customer who dyes nylon gives the standard color sample of nylon.
●The more dissimilar dyes are, the greater the color change.
Currently, computer color matching is definitely effective for color changes (light jumps) of three colors. Find the dye you are currently calculating (that is, the dye currently being used in the factory) The combination with the lowest color change value (but it may not completely eliminate the color change, the color change value may be large or small, unless it is a coincidence). </p
