Development and Application of Inkjet Printing Technology (I)

I. Introduction

Color printing has undergone considerable changes in a very short period of time: improved print quality, reduced prices, and high work efficiency... all of which are widely used by home, school, and even company line numbers. major factor. On the other hand, with the increase of computer speed, the large capacity of storage devices, the growth of digital imaging technology, and the use of a large number of graphics on the Internet, printers are now used not only to print some black and white texts, charts, reports, etc. , but with multiple uses, such as: photos, T-shirts, calendars, posters, stickers, business cards, mugs, etc., so the ink jet printer color stability, tone performance, high resolution, compatibility with the software The development of sex and ink-jet materials has become a standard of quality that we cannot ignore.
Epson's inkjet technology uses extremely small ink dots of 6 pl, and in a halftone manner, it sprays 1,440 dots per inch, which means that it produces 14,401,440 ink dots per inch (inch), resulting in eye Misinterpreting and forming different colors, the dots of ink that are ejected from each droplet are the same; HP's printer technology can accurately control the color of the ink droplets. It is the same position that controls the color ink and does not spray or spray. A drop of sixteen droplets is sprayed, which can result in seventeen tones. Each color has seventeen steps, so C, M, and Y colors have a total of 17X17X17=4913 color levels. The color of the above two brands is formed. The basic principle is very different, so the characteristics of color will definitely be different. There are also many new technologies, such as: PPIS (PerfectPictureImageSystem), micro-needle point piezoelectric ink-jet technology, true color conversion (AcuPhotoHalftoning), intelligent control of ink dot size, ink volume control, etc., all on the printer The print quality improvement can be of great help.
Second, the history of the development of ink jet printing Traditional printing has always been inseparable from the pressure transfer, to transfer must be plate, but the cost and time of plate making, no matter how progress can not meet a small number of diverse modern printing trends, in order to find a simple Low-cost printing methods have led to the development of unprinted and pressure-free inkjet printing. Speaking of the new darling of computer gamers nowadays, the inkjet printer dates back to 1884. The American CHRichard put water in the syringe, and the droplets of the needles flew out of the liquid droplets. Using the power plant to control its placement, a portrait can be formed on paper, which is called fog and ink printing. At that time, due to problems with needles and ink, the results were poor and it was not until 1960 that it officially entered the practical stage. Ten years ago, inkjet was used for bar code processing or product serial number printing. The variability of ink jet printing stencils increased the number of conveniences, but the resolution was still disappointing; it was not until nearly five or six years ago. The quality of ink printing has grown by leaps and bounds, but due to the lack of capacity of digital data storage equipment, it is difficult to quickly spread to the average family. In recent years, due to the advancement of digital technology, the progress of digital cameras and storage equipment are rapidly advancing. It is not difficult to obtain a high-quality digital image file. Therefore, more and more computer users are demanding ink-jet printing quality, and now almost Each household has a printer, and the share of inkjet printers accounts for 65% (1999, June). It can be seen that the quality and price of inkjet have been accepted by the public.

Third, the inkjet printing method There are more than 20 kinds of inkjet printing methods, but the basic principle is to first generate a small drop of ink, and then guide it to the set position, can be roughly summarized into a continuous type And intermittent type; the so-called continuous inkjet, regardless of imprinted or non-imprinted, in a continuous manner to generate ink droplets, and then the non-printed ink droplets recovered or dispersed; while intermittent inkjet only in the imprint Part of the ink droplets.
1. Continuous Jetting (Continuous Jet)
(I) DefletedDroptoPrint
After the ink is pressurized and ejected, vibrated, and decomposed into small ink droplets, after passing through an electric field, due to electrostatic effects, the small ink droplets fly directly in front of the electric field regardless of whether they are charged or not. When the electromagnetic field is deviated from the electromagnetic field, the ink droplet with a large charge will be attracted more strongly and have a greater tortuous range. On the contrary, the deflection is smaller. The uncharged ink droplets will be collected in the ink collection groove. (Figure 1)
(B) Undeflected DroptoPrint
Similar to the above one, the only difference is that the deviated charge is recovered, but the offset does not deviate from the straight line. (Figure 2)
(3) Electrostatic Dispersion (Electrostatic Dispersion) That Is Not Needed
The ink flow is still pressurized from the nozzle, but the tube hole is more slender, its diameter is about 10-15 microns or so, its orifice is fine and the ejected ink droplet will be automatically decomposed into one small ink. drop. These tiny droplets of ink are passed through the charging ring of the same electrode. Since these ink droplets are quite small, these charged ink droplets will split into fog ink again because of the repulsion of same-sex charges. At this time, they will lose their directivity and “not print”. Conversely, ink that is not charged will not split and form imprints. Can be used as a continuous tone printing. (Figure 3)
2. Intermittent Jet Printing
(I) Electrostatic Pull

The ink is ejected by electrostatic force, and the ink at the nozzle hole will form a convex half-moon pattern, and then juxtaposed by an electrode plate. The surface tension of the convex ink will be affected by the high voltage of the parallel electrode plate. damage. The ink droplets are then drawn by electrostatic force. The ink droplets are charged with static electricity and can be deflected vertically or horizontally to the set position or recycled on the mask. (Figure 4)
(B) Thermal Bubble Inkjet (ThermalinkJet)
Instantly heat the ink for a short time, so that the volume of gas in the vicinity of the resistor expands, and a small amount of ink will turn into vapor, and the ink is pushed out of the nozzle to fly to the surface of the paper to form an imprint. When the ink droplets are ejected, the temperature decreases and the temperature inside the ink chamber rapidly decreases. In the ink cartridge, the protruding ink is pulled back into the ink cartridge. (Figure 5)
Fourth, the factors that affect the quality of inkjet printing 1, color conversion In nature, all the colors are formed by the combination of different wavelengths of light. When light passes through the mirror, we can see the spectrum of light produced by various wavelengths. "Spectrum" can be said to be a natural phenomenon of continuous color mixing, but we can use it to define color changes and further manage the colors we need. On TV, movies, and computer screens, we use the additive method to handle color changes. He contains the main three colors, red, green, and blue (Red, Green, Blue), which are also known as the three primary colors (R, G, B). All colors can be generated by the overlapping of these three different colors of light, including white light and only three types of light can overlap. But for prints, the human eye uses reflected light to determine the difference in color. When you see a red paper, because the light is shining on the paper, the red light in the spectrum reflects, so you know it is red. of. So in print, we must use the "subtractive method" to define the color, which is the so-called three-color model of C, M, Y (Cyan Cyan, Magenta Magenta, Yellow Yellow). Because for colored light, red, green, and blue can be mixed white light, but when using watercolor or paint, will find that the color will be deeper, red, green, and blue are not white. (To be continued)