The principle and classification of digital inkjet printing

Digital ink jet printing is called color inkjet printing. It uses the input device such as a scanner or a digital camera to input the required pattern pattern to a computer. After being edited and processed by the electronic color separation system, the ink jet system is directly controlled by the computer. Dyestuffs or pigments are sprayed on fabrics for printing. Inkjet printing can be classified into continuous ink-jet and drop-on-demand according to the ink jet principle.

1. Continuous jet CIJ (continuous lnkJet)

The continuous jet principle is to apply a high-frequency oscillating pressure to the ink, so that the ink is ejected from the nozzle to form a uniform continuous droplet flow. At the nozzle there is an electric field that changes in synchronization with the graphic photoelectric conversion signal. The ejected droplets are selectively charged in the charged electric field. When the droplet stream continues to pass through the deflecting electric field, the charged droplets are deflected by the electric field, and the uncharged droplets continue to maintain the straight flight condition. Droplets flying in a straight line cannot reach the substrate to be printed and are recovered by the liquid trap. The charged droplets are ejected onto the substrate to be printed.

2, on-demand jet DOD (dro on Demand)

The working principle of the on-demand jet printing system is that when printing is required, the system applies high-frequency mechanical force and electromagnetic thermal shock to the color ink in the nozzle to form tiny droplets to be ejected from the nozzles, and the computer-controlled ejection To the set pattern. The most widely used on-demand spray type is the thermal ink jet technology, which relies on heat pulses to generate ink droplets. A computer controls a heated resistance wire to a specified temperature, causing the ink to evaporate (fog) from the nozzle. Another DOD technique is a piezoelectric injection system that is controlled by a computer to impose a potential on the piezoelectric material so that the piezoelectric material compresses in the direction of the electric field and expands in the vertical direction so that the ink is ejected.

Inkjet printing not only requires high-precision nozzle technology, high-precision control technology, but also requires high-purity, high-concentration, high-fastness, and high-stability inks to match.