Talking about Basic Theory and Quality Control of Ink Jet Printing (2)

Second, the factors that affect the quality of inkjet prints

In the process of rapid development of inkjet printing, it is inevitably constrained by a number of factors. At present, the factors that affect the quality of inkjet printing mainly include the following aspects:

1. Color conversion

For prints, people's eyes are determined by reflected light to determine the difference in color. When you see a red paper, because the light shines on the paper, the red light in the spectrum is reflected, so you know it is red. However, in print, we must use the subtractive method to define the color, which is the so-called three-color model of C, M, and Y. How to accurately convert the color (R, G, B) of the light source system into the ink jet or the color (C, M, Y, K) of the printing system is the key to influencing the printing quality.

2. Resolution

The so-called resolution (DotPerInch) refers to the number of dots printed on a one-inch width. Since the black ink is independent in inkjet printing, it is not obtained by the overprinting of Y, M, and C three-color inks. It has become the key to determining the quality of the black and white printing presses. For a color printer, because it is a multicolor overprint, it does not care about whether ink dots overlap. So the so-called true resolution and addressing resolution appear. As shown in Figure 4.

3. Levels

Printed images and images consist of many dots or pixels with different colors and brightness.

Each pixel has its own color and brightness. Because the color is analogous to the output method, the voltage is used to control the color so that each point can be displayed in a continuous color gradation (full tone). Therefore, even if the resolution is low, the output image still feels very natural and realistic. Therefore, the color scale is very important for the output image and image. The current ink jet printing technology can precisely control the color gradation of the ink droplets, and control the color ink from the same position to not spray one droplet to sixteen droplets, thereby controlling the color gamut of the output image.

4. Print head control

The ink dots are sprayed onto the paper through nozzles. In general, the nozzles and the print heads are made together. However, the precision of ink jet technology, cantilever gears, and drive belts are the main factors that determine the quality of the print head.

5. Ink

Ink jet printing generally uses non-toxic aqueous inks, usually oil-based or paraffin-based, which do not dry out in the nozzle but can be absorbed by the printing surface. In addition, the ink must also be fast-drying to prevent haziness on the paper. Therefore, the ink itself is also one of the factors that affect the print quality.

6. Substrate materials

After the ink reaches the substrate, due to the different internal structure of the different papers and the different surface coating, the ink has different permeation and absorption on the surface of the paper, which causes the color saturation and the color gamut space on the print product to be different. Generally speaking, under the same printing environment, the paper coating with relatively smooth surface coating has better ink jet printing effect, and many researchers have proved this through experiments.