On some printers, this is done with mechanical vibrations. Piezoelectric crystals change shape when a voltage is applied to them. As they do so, they force ink through the nozzles onto the paper. Each pixel in the image can be made up of a number of tiny drops of ink. The smaller the droplets, and the more of them, the richer and deeper the colors should be.
Piezoelectric crystals force ink through the nozzles onto the paper.
Courtesy of Tektronix . Inkjet printing, like conventional printing on a press, is binary. These printers can only put ink down or not put ink down. They can't control the density of each dot. A screening process maps the desired variations in density into variations in dot size.