So how does an inkjet printer actually work? First, it is good to understand that there are several different types of inkjet technologies. In the Marking and Coding world, the first bifurcation is the split between continuous inkjet (CIJ) and drop-on-demand (DOD) inkjet technologies.
Continuous inkjet (CIJ) technology utilizes a high-pressure pump, which directs ink through a print nozzle at very high velocity. A Piezoelectric field turns this stream of ink into microscopic droplets, which can then be deflected onto the print surface (substrate) by an electrostatic field. This produces the main benefit of CIJ technology, which is its ability to project ink at relatively large distances from print nozzle to substrate. CIJ printing systems require that the jet be constantly in use and flowing ink to avoid clogging. An unfortunate byproduct of the continuous flowing of inkjet ink and solvents in CIJ systems is the constant venting of volatile and toxic solvents into the environment.
Drop-on-demand (DOD) technology on the other hand does not require constantly flowing ink and solvent, but instead the ink and solvent is sealed in a container, typically a cartridge. DOD is further divided into thermal inkjet and piezoelectric inkjet applications.
Thermal inkjet applications utilize heat from behind the ink reservoir to eject droplets of inkjet ink from the print head. Piezoelectric inkjet systems utilize the application of current to piezoelectric material (such as lead zirconium titanate) to create a pressure wave, which ejects the inkjet ink through the print head.
All of these methods of inkjet printing effectively “throw” ink from the print head onto the printing surface, allowing in most cases for contact-less printing.
CIJ technology is relatively mature, and has been in use for over fifty years. Because of innovations in DOD technology, and because of environmental concerns as well as maintenance needs related to CIJ technology, a growing number of marking and coding applications are turning towards cartridge based DOD systems.
Innovation in inkjet ink formulations have helped to expand the application for inkjet printing beyond home and office printers for printing documents and photographs. Dye based inks are typically used for printing on paper and absorbent substrates, while more aggressive solvent-based inks are capable of printing on plastic, metal and even glass. Other applications of inkjet printers include printing photo luminescent inks for security and loss prevention, and even organic DNA encoded inks.