Fig. 1. (a) A schematic diagram of the dispensing principle using a piezoelectric actuator. The piezoelectric actuator (1) deforms the membrane of an ink channel when an electric potential (2) is applied. This deformation (4) applies a large enough pressure pulse to dispense a droplet (3).36 (b) Optical microscope image of the printhead of an Epson Stylus SX235W, consisting of 90 black nozzles and 29 nozzles per colour (CMY) with a vertical nozzle spacing of 211.67 μm (1/120 inch) and a nozzle diameter of 75 μm, (c) magnified view of one nozzle, (d) schematic representation of the printhead geometry. During one stroke the printhead moves horizontally over the paper, dispensing droplets on the indicated locations. This results in horizontal lines of dispensed droplets with a vertical distance equal to the fixed nozzle distance. Before the next stroke, the paper is slightly shifted along the paper feed direction. This allows the nozzles to fill the blank spots left behind due to the fixed nozzle distance. This operation repeats itself until the task is finished.
