Bill printing technology (Part 2)
2 Inkjet coding technology
inkjet coding technology refers to the use of some special technology to make very small ink droplets eject from one or more nozzles, and the ink droplets directly fall on the surface of the object to be sprayed after passing through the air to form a spray pattern. At present, there are three inkjet printing methods used by enterprises: Valve inkjet printing, continuous inkjet printing and pulse inkjet printing
(1) valve type spray printing is mainly used in the spray printing mark of the outer packaging box, and now it is rarely used.
(2) continuous spray printing
this technology has a wide range of applications. So far, there are mainly two kinds of printing used: deflection spray printing and binary spray printing
① deflection printing
it pressurizes the ink and sends it to the nozzle to form an ink flow. There is a piezoelectric device and a charging electrode behind the nozzle to charge or not charge each ink drop. The ink drops continue to move forward, forming a magnetic field. Under the action of the magnetic field, the charged ink droplets produce a corresponding amount of deflection according to their own charged amount. Finally, the ink drops pass through the air and fall on the surface of the printed object passing through the nozzle. The uncharged ink drops will not deflect and flow back for reuse. Among them, the representative brands are domino, IMAS, Willie, etc
② binary continuous spray printing
this technology is mainly used in the printing industry. For many years, it has been developed in the commercial field of spray printing on a large scale. The ink is sprayed from a series of closely arranged nozzles, and the ink flow is controlled by the piezoelectric device to form ink droplets. The ink dots that do not need to be sprayed are not charged and deflected, and then recycled by the recycling tank. In this way, the accuracy of the jet printing pattern is determined by the number of nozzles (horizontal) or the number of ink flows (vertical). At present, the application of this technology includes Sai angel and chase
(3) pulse jet printing
pulse jet printing nozzle is developed from the field of office printing, and its technology is mainly divided into piezoelectric jet printing and bubble jet printing. Now, in addition to being widely used in office inkjet printers, it also plays an important role in the printing industry. The main manufacturers of pulse nozzle include Hewlett Packard, etc
① the piezoelectric jet printing experimental machine should have no obvious vibration work and impact
its inkjet method is to use the surface tension of the ink in the nozzle to keep the ink in the nozzle. When it is necessary to spray printing, a pulse voltage is applied to the piezoelectric crystal, which will deform and reduce the volume of the ink occupied by the nozzle. In this way, a drop of ink is shot from the nozzle. Then, the piezoelectric crystal returns to its original state, and the new ink enters the nozzle again due to the surface tension. This is one of the methods. Another method is to heat the nozzle and use hot-melt ink. In this way, the ink that remains fluid in the nozzle will solidify on the colder surface of the printed object. This piezoelectric printing system can get good results on many sprayed surfaces, but it is easy to be scratched off in the process of touching
② bubble printing
it applies a voltage to two piezoelectric terminals. Due to the impedance between the terminals, the ink is instantly heated, forming a steam bubble. Due to the expansion of the bubble, a drop of ink is ejected from the nozzle. New ink is filled into the nozzle due to surface tension. Such products are mainly produced by HP and Hitachi
3. Two dimensional bar code technology
compared with one-dimensional bar code technology, it increases the bar code of text data, and has the advantages of large capacity, low cost, high accuracy, flexible coding method, strong anti-counterfeiting and confidentiality performance. At present, this technology has been applied in 1. Impact testing machine, public security, commercial finance, customs and other fields
QR code can be directly generated by various QR code generation software, and its content includes numbers, words, letters, patterns, etc. because each bar code contains different content and the complexity of QR code patterns, digital printing equipment is a good choice for QR code
there are two different symbol methods for QR code, namely, overlapping bar code and matrix symbol method. Among them, the overlapping bar code includes additional layout arrangement information, so that the information is always in the correct position, and the amount of information can reach 1K letters. It can be read by infrared, laser and CCD scanners. At present, this symbolic method has been adopted by many industrial organizations and industrial companies
matrix notation can provide higher information density. It uses a fixed width printed "honeycomb" or "feature" to represent 0 or 1. Because there is no boundary, it can give greater tolerance in printing and reading, and store more information. It has higher automatic error correction function than the overlapping type, and is more suitable for occasions where bar codes are easy to be damaged. In terms of reading, it can only be read by two-dimensional CCD scanner and can be scanned in all directions
4. magnetic printing technology
magnetic printing is a recording medium combining printing technology and recording technology. It can not only write data on magnetic carrier, but also see and read out. Therefore, it is widely used in finance, communication and other fields. Its printing technology is to use magnetic ink mixed with iron oxide for printing or hot stamping special tapes. The so-called magnetic ink refers to the ink prepared by magnetic particle pigments, binders, desiccants, antioxidants and other additives. Its carrier is mainly paper and plastic film base with uniform thickness, smooth surface, toughness, stable size, water resistance and corrosion resistance. Its printing process usually uses special magnetic tapes with special treatment to transfer the magnetic media to the substrate through hot stamping. The main products include magnetic cards, bank passbooks, boarding passes, parking lot toll passes, etc
5. variable data printing technology
variable data printing, also known as personalized printing, is a combination of electronic printing and data, which was introduced into the commercial printing industry in the 1990s. Unlike traditional commercial printing, it will not print redundant backup prints, so every print is very important. In the whole printing process, there is no waste. The binding or sealing of its prints should also be accurate and intact, because if there is damage, it will lead to the reprint of the whole batch of prints. To realize variable data printing, three basic conditions must be met: first, there are variable data processing applications and database systems; Second, support rip of variable data; Third, digital printing equipment
in short, with the continuous development of the bill printing industry, there will be more and more new anti-counterfeiting technologies with the function of power-off memory
recently
LINK
Copyright © 2011 JIN SHI