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Continuous inkjet printing (CIJ)

What is continuous inkjet printing (CIJ)?

Continuous inkjet printing (CIJ) is a mature technology. It is primarily used for coding and marking of products and packages. In this technology, a pump directs fluid from a reservoir to one or more small nozzles, which eject a continuous stream of drops at high frequency (in the range of roughly 50kHz to 175kHz) using a vibrating piezoelectric crystal. The drops pass through a set of electrodes which impart a charge onto each drop. The charged drops then pass a deflection plate which uses an electrostatic field to deflect drops that are to be printed. Undeflected drops do not reach the substrate but are collected and returned for re-use. The high drop ejection frequency of CIJ gives a capability for very high speed inkjet printing, suitable for such applications as the date coding of beverage cans. An additional benefit of CIJ is the high drop velocity (of the order of 50m/s), which allows for relatively large distances between the printhead and the substrate.

Historically, CIJ has enjoyed an advantage over other inkjet technologies in its ability to use inks based on volatile solvents, allowing for rapid drying and aiding adhesion on many substrates. The disadvantages of the technology include relatively low print resolution, very high maintenance requirements and a perception that CIJ is a dirty and environmentally unfriendly technology due to the use of large volumes of volatile solvent-based fluids. Additionally, the requirement that the printed fluid be electrically chargeable limits the applicability of the technique.