Inkjet Technology Overview

WHEN INKJET PRINTING FIRST CAME ON THE SCENE PRINT QUALITY WAS GENERALLY UNSATISFACTORY. HOWEVER, DUE TO DEVELOPMENTS IN HARDWARE (PRINTERS), SOFTWARE, INKS AND SUBSTRATES, VERY GOOD PRINTED RESULTS CAN NOW BE ACHIEVED. (IMPROVED PRINT QUALITY IS NOT ONLY DOWN TO BETTER PAPER, BUT A VARIETY OF CHANGES IN THE WHOLE ARENA)

In the early days of inkjet print technology development, poor colour image quality due to ink spreading and inter-colour bleeding (that is where the penetration of ink into the paper is too slow to absorb multiple ink drops on the same spot in short intervals) were widely recognized as the critical issues.

The initial solution which has continued to be built upon was the use of special coated media, the design of which takes into account drop volume, evaporation rate, penetration rate, porosity, etc (see Designs on Inkjet Paper, page 11).

But as inkjet print technology was developed and alternative solutions to the use of special coated media were sought, the use of solid (hot-melt) ink was introduced.

The idea being that on contact with the media, the ink solidifies almost immediately, without over-absorption or too much spreading, enabling brilliant colour and image reproduction. These inks have the advantage of being able to print on a wide variety of substrates such as glass and ceramics. However, they do not allow for a very high print resolution, hence at present the technology is not a market leader.

With this potential alternative solution, the door was now open to deeper exploration of the true opportunities of inkjet printing.

Continuous inkjet technology (The process in which a continuous stream of ink droplets are given an electrostatic charge which allows precise placement and frequency of droplets) and drop-on-demand inkjet technology (The procedure in which droplets of ink are forced through a nozzle in a controlled fashion, rather than in a continuous stream), soon became the two primary categories (see Chart 1), spawning their own technology sub-divisions. However, drop-on-demand is at present the most widely used technology with the vast majority of applications being printed using this method.

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