Abstract: In a method of nozzle failure detection in an ink jet printer having a plurality of ejection units including a nozzle and an associated liquid chamber with an electromechanical transducer, nozzle failure detection is performed, for each ejection unit, with a given minimum detection frequency. Each nozzle failure detection includes energizing the transducer with a waveform that does not lead to the ejection of a droplet but creates a pressure fluctuation that is sensitive to whether or not the ejection unit is in a malfunction state; measuring the pressure fluctuation in order to detect the malfunction state; defining a mask pattern that is independent of image contents to be printed; and when an image is being printed, performing the nozzle failure detection steps for each ejection unit at timings at which the respective nozzles are in pixel positions that belong to the mask pattern.

Abstract: A method for detecting an operating state of an ejection unit during the printing of an object of a print job the method comprising determining whether the ejection unit is in an operative state or in a malfunctioning state by analyzing a residual pressure wave generated in the liquid in a duct of the ejection unit by an actuation pulse. Further, the method comprises scanning the location of a recording medium onto which liquid has been ejected in order to perform an additional determination of whether the ejection unit is in an operative state or in a malfunctioning state. The method uses both determinations to build feedback information in the form of labeled data that is used in subsequent executions to improve the result of the determinations performed by analyzing a residual pressure wave generated in the liquid.

Abstract: In a method of nozzle failure detection in an ink jet printer having a plurality of ejection units including a nozzle and an associated liquid chamber with an electromechanical transducer, nozzle failure detection is performed, for each ejection unit, with a given minimum detection frequency. Each nozzle failure detection includes energizing the transducer with a waveform that does not lead to the ejection of a droplet but creates a pressure fluctuation that is sensitive to whether or not the ejection unit is in a malfunction state; measuring the pressure fluctuation in order to detect the malfunction state; defining a mask pattern that is independent of image contents to be printed; and when an image is being printed, performing the nozzle failure detection steps for each ejection unit at timings at which the respective nozzles are in pixel positions that belong to the mask pattern.

Abstract: A method of operating a droplet ejection device including an ejection unit arranged to eject droplets of a liquid and including a nozzle formed in a nozzle face, a liquid duct connected to the nozzle, and an electro-mechanical transducer arranged to create an acoustic pressure wave in the liquid in the duct, includes detecting low-viscosity liquid on the nozzle face by analyzing a signal obtained from the transducer.

Abstract: A method for detecting an operating state of an ejection unit during the printing of an object of a print job the method comprising determining whether the ejection unit is in an operative state or in a malfunctioning state by analyzing a residual pressure wave generated in the liquid in a duct of the ejection unit by an actuation pulse. Further, the method comprises scanning the location of a recording medium onto which liquid has been ejected in order to perform an additional determination of whether the ejection unit is in an operative state or in a malfunctioning state. The method uses both determinations to build feedback information in the form of labeled data that is used in subsequent executions to improve the result of the determinations performed by analyzing a residual pressure wave generated in the liquid.

Abstract: A droplet ejection device has a nozzle head with a plurality of ejection units, each of which includes a nozzle, a duct connected to the nozzle, and an electromechanical transducer arranged to create a pressure wave in a liquid in the duct so as to expel a droplet of the liquid from the nozzle. The device further includes an electronic control circuit arranged to apply control signals to the transducers and to receive detection signals that are generated in the transducers in response to the transducer being exposed to pressure fluctuations. The nozzle head includes a reference duct which has an electromechanical transducer serving as a reference transducer. The control circuit is arranged to subtract a detection signal of the reference transducer from a detection signal of at least one of the ejection units.

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.

Abstract: A jetting device includes an ejection unit arranged to eject a droplet of a liquid. The ejection unit includes a nozzle, a liquid duct connected to the nozzle, and an electro-mechanical transducer arranged to create an acoustic pressure wave in the liquid in the duct. The jetting device further includes a filter arranged to filter the liquid being supplied into the duct and a filter status detection system arranged to detect an obstruction status of the filter by measuring a property of the liquid in the duct. The filter status detection system includes a circuit configured for measuring the electric response of the transducer, for recording changes in the electric response that represent pressure fluctuations induced by the acoustic wave in the form of a time-dependent function, and for judging the obstruction status of the filter on the basis of that function.

Abstract: For assessing the functioning of an ejection unit of an inkjet print head, a comparison of a residual pressure wave with a residual pressure wave reference is employed. To enable assessment during printing, multiple residual pressure wave references are provided, each relating to a condition relevant to the residual pressure wave. Such a condition may relate to an actuation status of an adjacent ejection unit which may cause crosstalk, for example. When performing the assessment, the condition during assessment is taken into account, for example for selecting a suitable residual pressure wave reference, such that an appropriate and correct assessment can be performed independent from the conditions during assessment.

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.

Abstract: An inkjet print head includes an ejection unit having a liquid chamber for holding an amount of liquid, a electromechanical transducer operatively coupled to the liquid chamber for generating a pressure wave in the amount of liquid and a nozzle in fluid communication with the liquid chamber for enabling a droplet of the amount of liquid to be ejected through the nozzle. A method for detecting an operating state of the ejection unit includes the consecutive steps of actuating the electromechanical transducer to generate a pressure wave in the liquid; actuating the electromechanical transducer to suppress a residual pressure wave in the liquid; sensing an amplitude of the residual pressure wave in the liquid; and based on the result of the sensing step determining that the ejection unit is (i) in an operative state if the amplitude of the residual pressure wave is below a threshold or (ii) in a malfunctioning state if the amplitude of the residual pressure wave is above the threshold.

Abstract: An inkjet print head includes a droplet ejection unit having a pressure chamber; a first actuator configured for changing a volume of the pressure chamber; a second actuator configured for changing the volume of the pressure chamber; and a nozzle orifice. The inkjet print head further includes a control circuitry operatively connected to the first actuator and the second actuator. The control circuitry includes a drive circuitry for supplying a drive signal to at least one of the first and the second actuator; a sensing circuitry for receiving a sense signal from the first actuator; and a switch circuitry for switching a connection of the first actuator between a connection to the drive circuitry and a connection to the sensing circuitry.

Abstract: A droplet ejection device has a nozzle head with a plurality of ejection units, each of which includes a nozzle, a duct connected to the nozzle, and an electromechanical transducer arranged to create a pressure wave in a liquid in the duct so as to expel a droplet of the liquid from the nozzle. The device further includes an electronic control circuit arranged to apply control signals to the transducers and to receive detection signals that are generated in the transducers in response to the transducer being exposed to pressure fluctuations. The nozzle head includes a reference duct which has an electromechanical transducer serving as a reference transducer. The control circuit is arranged to subtract a detection signal of the reference transducer from a detection signal of at least one of the ejection units.

Abstract: A jetting device includes an ejection unit arranged to eject a droplet of a liquid. The ejection unit includes a nozzle, a liquid duct connected to the nozzle, and an electro-mechanical transducer arranged to create an acoustic pressure wave in the liquid in the duct. The jetting device further includes a filter arranged to filter the liquid being supplied into the duct and a filter status detection system arranged to detect an obstruction status of the filter by measuring a property of the liquid in the duct. The filter status detection system includes a circuit configured for measuring the electric response of the transducer, for recording changes in the electric response that represent pressure fluctuations induced by the acoustic wave in the form of a time-dependent function, and for judging the obstruction status of the filter on the basis of that function.

Abstract: A liquid jetting device comprising a plurality of ejection units each of which is arranged to eject a droplet of a liquid and comprises a nozzle, a liquid duct connected to the nozzle and an electro-mechanical transducer arranged to create an acoustic pressure wave in the liquid in the duct, the device further comprising an electronic control system arranged to receive a pressure signal from at least one of the transducers and to generate a transducer control signal on the basis of the received pressure signal and to control the transducers of said plurality of ejection units to operate in a mode of operation selected from a variety of different modes of operation, wherein the control system is arranged to detect an acoustic property of the liquid of the basis of the received pressure signal and to select the mode of operation in accordance with the detected property, the control system being arranged to deliver transducer control signals to the transducers, which control signals are derived from a common bas

Abstract: An inkjet print head includes an ejection unit having a liquid chamber for holding an amount of liquid, a electromechanical transducer operatively coupled to the liquid chamber for generating a pressure wave in the amount of liquid and a nozzle in fluid communication with the liquid chamber for enabling a droplet of the amount of liquid to be ejected through the nozzle. A method for detecting an operating state of the ejection unit includes the consecutive steps of actuating the electromechanical transducer to generate a pressure wave in the liquid; actuating the electromechanical transducer to suppress a residual pressure wave in the liquid; sensing an amplitude of the residual pressure wave in the liquid; and based on the result of the sensing step determining that the ejection unit is (i) in an operative state if the amplitude of the residual pressure wave is below a threshold or (ii) in a malfunctioning state if the amplitude of the residual pressure wave is above the threshold.

Abstract: For assessing the functioning of an ejection unit of an inkjet print head, a comparison of a residual pressure wave with a residual pressure wave reference is employed. To enable assessment during printing, multiple residual pressure wave references are provided, each relating to a condition relevant to the residual pressure wave. Such a condition may relate to an actuation status of an adjacent ejection unit which may cause crosstalk, for example. When performing the assessment, the condition during assessment is taken into account, for example for selecting a suitable residual pressure wave reference, such that an appropriate and correct assessment can be performed independent from the conditions during assessment.

Abstract: In a method for identifying of and distinguishing between at least two different predetermined disturbance states in an inkjet print head, the method comprises providing a disturbance identification input signal; applying the disturbance identification input signal to an actuator, the actuator being part of an ejection unit of an inkjet print head; receiving a residual pressure wave output signal; and analyzing the residual pressure wave output signal.

Abstract: A liquid jetting device comprising a plurality of ejection units each of which is arranged to eject a droplet of a liquid and comprises a nozzle, a liquid duct connected to the nozzle and an electro-mechanical transducer arranged to create an acoustic pressure wave in the liquid in the duct, the device further comprising an electronic control system arranged to receive a pressure signal from at least one of the transducers and to generate a transducer control signal on the basis of the received pressure signal and to control the transducers of said plurality of ejection units to operate in a mode of operation selected from a variety of different modes of operation, wherein the control system is arranged to detect an acoustic property of the liquid of the basis of the received pressure signal and to select the mode of operation in accordance with the detected property, the control system being arranged to deliver transducer control signals to the transducers, which control signals are derived from a common bas

Abstract: A method is provided to determine a droplet ejection state of a pressure chamber of a piezo-actuated inkjet print head, the method comprising a step of analyzing that includes filtering a residual pressure wave signal using a predetermined filter. The filter is designed to remove a low-frequency signal contribution generated by piezo material of the piezo actuator. Such a low-frequency signal contribution results from a piezo material property that varies over all piezo actuators without affecting the functional properties of the piezo actuator. Hence, for controlling the operation of the inkjet print head, in particular for controlling a droplet size and a droplet speed, such a signal contribution may be removed enabling a simple and nozzle-independent analysis of the residual pressure wave signal.