Oce-Technologies B.v.

Marko Mihailovic

Amol A Khalate

Hylke Veenstra

Cornelis W M Venner

Tjerk E C Hummel

Johannes M M Simons

Cor Venner

Theo Hummel

Johannes MM Simons

Cornelis WM Venner

Tjerk EC Hummel

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.

Droplet ejecting device

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.

Jetting device with filter status detection

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.

Method for detecting an operating state of an inkjet print head nozzle

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.

Method for detecting an operating status of an inkjet nozzle

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 basic waveform that is specified by mode parameters, each mode of operation of the device is specified by a different set of mode parameters, the waveform comprises a jetting pulse and quench pulse following on the jetting pulse, and one of the mode parameters is a time delay between the start of the jetting pulse and the start of the quench pulse.

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Venlo, Netherlands

Marko Mihailovic