Patent ID: 10471710

Abstract:
In a method for detecting a disturbance in an ejection unit of an inkjet print head, the ejection unit of the inkjet print head includes a pressure chamber for holding an amount of liquid and is in fluid communication with a nozzle orifice; and an actuator operatively coupled to the pressure chamber for generating a pressure wave in the liquid in the pressure chamber for ejecting a droplet of the liquid through the nozzle orifice upon application of a droplet ejection pulse. The method determining at least one resonance frequency of the pressure chamber; determining a disturbance detection pulse for generating a pressure wave in the liquid in the pressure chamber taking into account the resonance frequencies previously determined, wherein the disturbance detection pulse has a frequency spectrum different from a frequency spectrum of the droplet ejection pulse; detecting a residual pressure wave in the liquid in the pressure chamber; and analyzing the residual pressure wave previously detected for determining whether a disturbance for droplet ejection is present in the ejection unit. With this method, disturbances in the ejection unit may be derived from the residual pressure wave more reliably and easier.