All of our large format presses use inkjet printing as the means for depositing ink droplets onto a substrate. While the basic inkjet technology that’s used in a home inkjet printer is similar to that used in our high end devices the difference is speed and resolution. Built into the inkjet print heads are hundreds of tiny nozzles, also called jets. Inside these print heads, microscopic piezoelectric elements (similar to crystals) are placed just behind the print nozzles. When an electrical charge is applied to them, these crystals bend backward, forcing out a precise amount of ink onto the substrate. Because the electrical charges can be turned on and off like a switch, there is an enormous amount of control over the amount of ink being ejected through the nozzle while also creating perfectly round dots at different droplet sizes. As the paper moves past the print heads, the nozzles spray ink onto it, forming the letters and images. The ongoing challenge for the printer manufacturers is to figure out how to make the droplets smaller and smaller in order to increase the ability to have higher and higher resolution of the image being printed. To increase speed the manufacturers simply add more and more nozzles that work in unison to spray a wider swath of image in each pass.
As an example our Agfa Anapurna printer has print heads that can produce tiny drops as small as 12 picoliters (a picoliter is a trillionth of a liter) to produce a super high resolution of 720 x 1,440 dpi.
You can see from the video below how the press moves the group of print heads back and forth across the substrate being printing on. The print heads have tubes connected to them that deliver the ink from a ink tank.