A voltage is applied to the two terminals. Due to the resistance between the terminals, the ink is heated to form a vapor bubble, and a drop of ink is ejected from the nozzle due to the expansion of the chlorine bubble. When the voltage between the terminals is removed, the air bubbles disappear and a new ink fills the nozzles due to surface tension. Like piezo-electric printing technology, a series of nozzles can be arranged together to get a larger print range. The degree of resolution is largely determined by the denseness of the arrangement of the nozzles.
The ink characteristics are particularly important for the normal operation of the bubble jet system. In the office, it is possible to control the surface of the printed matter to match it with the ink, but it is completely different in the production environment. For this reason, the impact of bubble jet printing technology in the field of product coding has been limited. However, in the case of bubble jet printing inks, we can get excellent jet printing results.
Continuous inkjet continuous inkjet coding has a wide range of applications, it may be the most diverse technology. From the mid-1970s to the end of the 1970s, the early continuous inkjet coding machines were complicated to operate and had frequent failures. This impression still exists, but the situation has changed, just as the car no longer leaks when we drive. The latest continuous inkjet coding system requires only the operator to press the ON/OFF key and perform routine maintenance once a week, and maintains much less maintenance than other ill-fated devices. There are two related but different continuous inkjet coding techniques:
____ deflected printing
____ Binary Printing Deflection Deflection Printing Deflection Printing has been commercialized since the early 1970s, and it may be the most developed technology used in the production environment. Although the principle is quite simple, many control circuits have been combined for many years to ensure reliability and ease of use. (The system is shown in Figure 4:)
The ink was applied to the nozzle after pressurization, forming an ink flow of about 20 M/S. There is a piezoelectric device behind the nozzle. When the voltage is applied, the device will be displaced. This displacement will disturb the ink flow. If the frequency of the electrical signal applied to the piezoelectric device resonates with the ink jet frequency, the ink flow will break into The same size, the same pitch of ink droplets. In the position where the continuous ink flow breaks into a series of ink droplets, there is a charging electrode. If the frequency of the pulse voltage on the charge electrode is the same as the frequency at which the ink stream breaks, each droplet will be charged with the corresponding charge. The ink drops continue to move past a pair of deflector plates. The voltage on the deflector plate is constant (for example, +/-5KV), forming an electrostatic field. Under the effect of the electrostatic field, the charged ink drops respond to the direction of one of the deflector plates according to the amount of charge they have. The amount of deflection. Finally, the ink droplets pass through the air and land on the surface of the printed object that passes through the print head. The uncharged ink droplets are not deflected and are collected in the recovery tank at the bottom of the spray head and finally recirculated to the nozzle through an ink reservoir.
Thus, approximately, the pattern of ink jet printing corresponds to the pulse voltage applied to the charging electrode. The actual process is not so simple. We must synchronize the drop breakage with the charging of the charging pad, we must consider the mutual exclusion between the charged droplets, and even the aerodynamic problems of flying drops. Users of continuous inkjet coding machines do not feel these problems, but it is these problems that make designing continuous inkjet coding machines interesting.
Because ink jets are continuous, continuous inkjet printers can use many types of inks, especially those that dries very quickly (within 1 second). Therefore, continuous inkjet coding technology is ideal for printing on non-permeable surfaces such as cans and plastics that need to be processed quickly after printing. In addition, more colorful pigment inks can also be used.
Since continuous jet printing has a relatively high jetting speed, the jet printing distance of the continuous jet printing is usually far more than the jet printing distance (generally more than 10 mm), and the jet printing quality does not decrease. The placement of the nozzles allows for a great deal of choice.
The concept of binary jet printing binary continuous jet printing technology is as old as the deflection jet printing technology. This technology was developed toward the high-speed (high-cost), wide-spray printing commercial field in the early days. As technology advances, binary printing will be practical in a very short period of time. (The system is shown in Figure 5:)
The ink is ejected from a series of closely spaced nozzles. The print resolution is 4-8 dots/mm. The ink flow is broken by the piezoelectric device into ink droplets. The breakage pattern is similar to that of deflection printing (although the binary printing has More ink flow). The ink dots that do not need to be printed are charged, deflected, and then recovered by the recovery tank. The ink dots that need to be printed are not charged and do not deflect. They directly hit the surface of the printed object. In this way, the width of the print pattern is determined by the number of nozzles or the number of ink flows. Of course, we can also use rechargeable ink jet printing to recover the uncharged ink droplets.
Binary jet printing is less than offset printing, but it is still much larger than valve printing. In principle, a wide variety of inks for deflected jet printing can be applied to binary jet printing. In the future, whether to use binary printing or offset printing will depend on whether the printing is focused on the number of information lines or the speed and cost. When printing more than three lines of information at the same time, binary printing is undoubtedly faster than deflection printing. However, binary printing is more expensive and will require more manual operations in early applications, especially when using different heterosexual inks. Basically, binary printing and deflection printing will coexist, because at present, they provide customers with the most diverse and effective solutions in the field of on-line printing.
About the Author:
The author, MIKE KEELING, has been working in the field of inkjet coding since the mid-1970s. He devoted many parts of his personal career to development, advancing the application of continuous inkjet coding technology. Although the physical principles behind continuous inkjet coding technology were known decades ago, it was not until the 1970s that MIKE KEELING and his colleagues in the Cambridge Product Development Advisory Group converted continuous inkjet coding technology into practical. In the process of practical continuous inkjet coding technology, a series of ink jet coding Machine manufacturers were created. In the end, MIKE KEELING and his colleague HILL WEINBERG founded LINX in 1987. LINX Inkjet Technology Co., Ltd. specializes in continuous inkjet coding and laser coding and is now a global company. MIKE continues to play an active role as a vice president. Hong Kong Dajia Asia Co., Ltd. provides a variety of inkjet coding equipment.
