With the continuous progress and development of the digitization process, inkjet printing technology has become an important technical means in the field of digital printing because of its low cost and good environmental protection features. Inkjet printing equipment mainly includes: small inkjet printers, large format inkjet printers, inkjet printing systems, and the like. As a product of digitalization and computer technology, inkjet printing covers part of the printing market that cannot be covered by traditional printing, and it is gradually expanding into many fields. The market prospect is very broad.
First, the basic principles and methods of ink jet printing
Inkjet printing is a non-contact, pressureless, and non-printing printing method. It is composed of a system controller, an inkjet controller, a nozzle, a substrate drive mechanism, and the like. The ink is controlled by an inkjet controller, The nozzle is printed on the substrate. Color inkjet printers usually have two modes, high temperature and high pressure printing and normal temperature and pressure printing. The former is represented by Canon's bubble technology and HP's thermal technology, which is represented by Epson's ultra-micro piezoelectric printing technology. Thermal foaming relies on the heat of a small resistor to evaporate the surrounding ink and generate bubbles. The expansion of the bubbles compresses the ink and ejects it from the nozzle to the substrate. After the ejection, the bubbles disappear, and the new ink is sucked from the ink tank to create continuous Bubble work. The micro-piezoelectric inkjet technology puts the piezoelectric chip on top of the inkjet nozzle, adds a little current to the chip, generates vibration, and ejects the ink by vibration.
1. Continuous inkjet printing
(1) After the ink is printed by the ink droplets that have been deflected, they are ejected, vibrated, and decomposed into small ink droplets. After passing through an electric field, due to the electrostatic effect, the small ink droplets fly straight over the electric field, regardless of whether they are charged or not. flight. When the electromagnetic field is deviated from the electromagnetic field, the ink droplet with a large charge will be strongly attracted and deflected. On the contrary, the deflection is smaller. Uncharged ink droplets will be collected in the ink collection trench (see Figure 1).
(2) Printing with ink droplets that are not deviated is very similar to the above-mentioned one. The only difference is that the deviated charge is recovered, and instead of deviating the charge, the imprint is formed directly (Figure 2).
(3) Unnecessary ink droplets make the electrostatic splitting ink flow still pressurized by the nozzle orifice, but the tube hole is more slender, its diameter is about 10 to 15 microns or so, and its orifice is fine to eject The ink droplets are automatically broken down into tiny droplets. When these tiny droplets of ink pass through the charged ring of the same electrode, these charged droplets of ink recombine into mist and ink because of the repulsion of the same-type charges, and at this time, they lose their directivity and are not printed. Conversely, ink droplets that are not charged will not split and form imprints. Can be used as a continuous tone printing (Figure 3).
2. Intermittent inkjet printing
(1) Electrostatic pulling is used to eject ink by electrostatic attraction. The ink at the injection hole forms a convex half-moon pattern, and then is juxtaposed with an electrode plate. The surface tension of the embossed ink is affected by the parallel electrode. The high voltage on the board is destroyed. The ink droplets are then pulled out by the electrostatic force. The ink droplets are charged with static electricity and can be deflected vertically or horizontally to the set position or on the mask (see Figure 4).
(2) The hot bubble type ink jet heats the ink instantaneously for a very short time, expands the volume of the gas in the vicinity of the resistor, and also causes a small amount of ink to become vapor, pushing the ink out of the nozzle, causing it to fly to the paper On the surface, an imprint is formed. After the ink droplets are ejected, the temperature is then decreased, so that the temperature in the ink chamber is also rapidly lowered, and then the protruding ink is pulled back into the ink cartridge by capillary principle.
Second, the application of inkjet printing technology in China
China's ink-jet printing industry is not far from the start-up time of foreign countries, but there is still a big gap between R&D, production, sales, and applications compared with developed countries such as the United States and Japan. In terms of regional distribution, it mainly concentrates on economically developed Guangzhou, Shenzhen, Shanghai, and Beijing. At present, the application of domestic inkjet printing is in a polarization situation. At one end is a low-end market. Most of the equipment used is a non-production inkjet printer, and most of the printing jobs are short-lived black-and-white activities, with a small amount of color live. At the other end is the high-end market. Most of the ink jet printing equipment used by practitioners is a production inkjet digital printer. In addition, India is not only an ultra-short version of color printing, but also has a lot of personalized, variable data printing color printing products. . Customers of these digital printing companies pay more attention to quality and service, and have high requirements for color and print quality.
In addition, as the resolution and speed of ink jet printing continue to increase, several application branches are formed.
1. As a digital camera output device, digital photos are directly output to form a competitive situation with traditional analog photography and photo processing. Although the current price of inkjet digital printing is relatively high, the market will further expand as the cost decreases.
2. Inkjet digital proofer or output machine. The proofing effect of this equipment is close to the printing effect. Many publishing houses output proofs in this way for proofreading and evaluation of documents to adjust printing equipment and improve printing quality.
3. Inkjet printers have entered the short-run, fast-printing market, becoming the main model competing with small-sized lithographic printing presses, and occupying market share at an unprecedentedly high speed. There are now many foreign manufacturers participating in the competition.
4. Digital inkjet equipment has entered the large advertising inkjet market and challenges the traditional screen printing industry. This printing method has been widely used in street advertisements, body advertisements, light boxes, plaques, and the like with a lower resolution, a larger printing width, and the ability to continuously print without length limitations.
5. The use of inkjet printers online has better anti-counterfeiting effect. Manufacturers with lower economic strength are able to spray information on dates and other information in key parts of the package through clever use of inkjet printers, which can play a certain anti-counterfeiting effect. Inkjet printers combined with anti-counterfeiting inks have better anti-counterfeiting effects. The on-line use of inkjet printers has the function of design and investment security. The anti-counterfeit inks have secretive anti-counterfeiting functions. The combination of the two uses triple-anti-counterfeiting functions.
Third, the advantages and constraints of inkjet printing technology
1. The advantages of inkjet printing technology
(1) Inkjet printing is a type of digital printing, completely out of the cumbersome procedures of the traditional printing process, the requirements of color overprinting and trapping is not high, do not need to consider the accuracy of registration, short job preparation time, fast response to the market , Short production cycle, can complete the production of digital proofs and short-run jobs with high efficiency and cost efficiency.
(2) Realizing variable data printing and custom printing. The image information can be changed at any time to meet the user's short-run printing jobs and personalized printing needs, such as personal albums, product descriptions, materials, test-marketing products, and packaging samples.
(3) One-off printing, reduced waste, more flexible printing services, usually have an advantage in 1000 prints.
(4) Digital features make it easier to introduce digital integration technologies such as digital asset management, automated workflows, and color management.
(5) It can realize remote printing and provide remote printing service through internet transmission, especially suitable for quick printing of chain operations across regions.
(6) Most inkjet printing technologies are non-contact printing and can be replicated on a variety of substrate materials, such as variable inkjet printing on a variety of commercial production lines.
(7) The digital web inkjet printing device can be limited by the length of the paper and can realize the reproduction of large-format, panoramic works.
2. Constraints of inkjet printing technology
Although digital printing, inkjet printing has a market share of about 5%. However, the development of inkjet printing is more or less constrained by some factors. At present, the following factors affect the quality of inkjet printing.
(1) Color conversion. How to accurately convert the color (R, G, B) of the light source system into inkjet or printed system (C, M, Y, K) is very complicated, but only by accurately converting the color can we obtain the truth. , high quality effect. Therefore, accurate color conversion technology is an important key to the quality of inkjet printing.
(2) Resolution. In black and white ink-jet printers, the higher the resolution, the finer the color-graded dots printed, the better the printing quality. But for color ink jet printers, the resolution refers to how many ink dots can be printed in a width of 1 inch, regardless of whether the ink dots overlap.
(3) Levels. The current ink jet printing technology can precisely control the ink droplet color scale, and the control of the color ink from the same position does not spray to spray one drop until it sprays 16 drops.
(4) Print head control. The dots of ink are ejected onto the paper through nozzles. In general, the nozzle and the print head are made together, so the technology of the print head itself is very important, and the left and right print heads are the inkjet technology and the cantilever gears of the printing presses. Drive belt precision.
(5) Ink. Inkjet printing inks are special inks of moderate viscosity and should have non-toxic, stable, non-blocking nozzles, good moisture retention, good jetting properties, and non-corrosive properties to the metal components of the showerhead. At present, ink-jet inks are mostly dye-based inks, and the ink of the ink-jet printer must also have sufficient surface tension to prevent the ink from spattering when ejected. In addition, the ink should have quick-drying properties to prevent haziness on the paper. Therefore, the ink itself is also one of the factors that affect the print quality.
(6) Substrate material. Inkjet printing paper requires paper with a smooth surface and a certain degree of sizing. The ink sprayed is evaporated and dried. The dots of ink are circular, and the printed letters are clear and the graphics are beautiful. Color inkjet printing paper, preferably with a very thin layer of transparent coating on the surface, can quickly absorb ink, but also to avoid light scattering, in order to get the ideal print.
Fourth, the prospect of inkjet printing
At present, the color performance and high image quality of inkjet printing have satisfied most consumers. Digital proofing has mostly been achieved using inkjet methods, and its advantages in large-format printing are increasingly evident, and it has begun to march into the field of packaging and printing.
However, the time for inkjet printing is still too slow, and the requirements for paper are also high. Although there are many special papers for inkjet printing on the market, the prices are high and it is difficult for general families and students to use them universally. A high-quality A4 image is often printed, it will cost tens of dollars in vain, so that inkjet printing technology can be widely applied to all kinds of paper, it is now the most urgent need to develop technology, if it is to make special It is not easy for the special paper of the material to be cost-effective, so developing a new ink composition is a direct and effective method. Another change in inkjet printing technology can also achieve this goal, such as: HP continues to do more precise control over the amount of ink supply, so that the ink droplets will not spread too serious; Tektronix also invested a lot of resources to develop new wax printing technology. In addition, ink-jet printing has the disadvantages of poor light resistance and too high machine prices, so there is still some way to go before it becomes pervasive.
Fortunately, the world's major printer manufacturers have been committed to the further improvement and development of inkjet printing technology, the development of better printing materials, research of new ink composition, change the inkjet technology ... ... continue to introduce new. On this basis, inkjet printing will increasingly adapt to today's small and varied modern printing trends with its technical advantages of no-version and variable-printing, showing an increasingly satisfactory development.
V. Conclusion
The rapid progress of inkjet printing has been superior to traditional printing in quality, and traditional printing will face another impact. In the near future, larger, faster and higher quality inkjet printing technologies that support double-sided proofing, UV-resistant and water-resistant UV inks will penetrate the broader printing market, providing users with faster and more cost-effective solutions. Low output device. As market demand continues to expand, inkjet printing will also infiltrate the digital workflow like a spring breeze.
Source: Ke Yin Network