The principle of keeping the ink of the inkjet printer dry in the nozzle

To put it simply, the ink pressure in the nozzle of the printer must be low enough (or negative pressure), because the surface tension of the ink keeps the ink in the nozzle. When printing is required, a pulse voltage is applied to the piezoelectric On the crystal, the piezoelectric crystal deforms, reducing the volume of the ink cavity of the nozzle, so that a drop of ink is ejected from the nozzle. Then, the piezoelectric crystal returns to its original shape, and new ink enters the nozzle due to surface tension. By arranging a large number of nozzles side by side, the ideal printing width and resolution (usually 8-6 dots/mm) can be obtained. Although the print resolution can be improved by slanting the print head of the printer (this will sacrifice the print height), the print resolution is basically determined by the nozzle pitch. More precise improvements can make each piezoelectric crystal drive more nozzles (for example, 8), 32 piezoelectric crystals can drive the ink in 256 nozzles, so that there will be a larger printing range, of course There are only 32 programmable drop points on the printed surface. Because the system is not continuous, the ink must remain fluid in the nozzle and dry on the surface to be printed. The ink used in piezoelectric jet printing is usually oil-based or paraffin-based. The ink of these two types of inkjet printers will not dry out in the nozzle, but can be absorbed by the printing surface. Piezoelectric jet printing also uses some quick-drying inks, which still take a long time (approximately 10 seconds) to dry. When the product needs to be processed quickly after printing and smudges are prohibited, the use of fast-drying ink will cause problems. In order to prevent the ink from drying out in the nozzle, we can also apply a lower pulse voltage to the piezoelectric crystal, which will slightly disturb the ink in the nozzle, and the ink in the nozzle will not dry out. This method relies on changes in the ink composition of the inkjet printer or more sophisticated mechanical improvements. Another way to achieve piezoelectric jet printing is to heat the nozzle while using hot-melt ink. In this way, the ink held as a fluid in the nozzle will solidify on the colder surface of the printed matter. This piezoelectric printing system can get good results on many surfaces to be printed, but it is easy to be scratched off in the process of touching. In addition to the problem of ink drying in the nozzle, another problem that needs attention is that the nozzle is very sensitive to vibration. The vibration can cause the ink to be shaken out of the nozzle and ink cavity, so that the surface tension cannot make the ink fill the nozzle, and the system must be restarted.