Commercial continuous inkjet (CIJ) printers have been in the market for about 50 years.  They are used to produce codes and marks on mass-produced products.   CIJ is ideally suited to coding and marking applications on production lines because it is fast and non-contact.

Continuous inkjet (CIJ) printers operate by forming drops from a jet of ink, charging them electrostatically and subsequently deflecting the charged drops with an electric field to produce an image on a print medium.  A continuous inkjet printer is so-called because it is constantly jetting ink and forming drops.  The printer uses a charging mechanism to select the drops that will be used to print.   Any unused droplets are collected and returned to the main body of ink.  As the printer is selecting drops by electrical charging it is able to print at high speeds and is restricted only by the rate at which drops can be formed.

Typically drop formation is achieved by forcing electrically conducting ink through a nozzle and applying a disturbance to the ink at the right frequency. The formation of suitable drops depends on a number of factors, including the velocity of the ink jet, the frequency of the applied disturbance, the size of the nozzle and the viscosity of the ink.  Continuous inkjet printers commonly make use of inks that consist in part of volatile organic solvents, which are used to ensure fast-drying times of the printed message.