US Patent 10099473 Evaluating print nozzle condition

Systems and methods for evaluating the condition of a print nozzle are described. In one example, impedances across the print nozzle are measured. Subsequently, first test result and second test result are determined and registered at a first predetermined time instant and at a second predetermined time instant, respectively. The first test result and the second test result are obtained based on the measured impedances. Based on the first test result and the second test result, the condition of the print nozzle, is determined.