Abstract: An electrical circuit for measuring the shape of a voltage waveform in a print head of a printer includes an integrated circuit for generating one or more voltage amplitude waveforms. The electrical circuit includes an inkjet drop forming unit including a plurality of inkjet chambers, wherein each of the plurality of inkjet chambers includes a piezoelectric actuator and an ink nozzle, and a connecting circuit between the integrated circuit and the inkjet drop forming unit suitable for applying one of the one or more voltage amplitude waveforms generated by the integrated circuit to the piezoelectric actuator in one of the plurality of inkjet chambers. In order to measure the shape of the one or more generated voltage amplitude waveforms via capacitive crosstalk, the electrical circuit also includes a conductor in physical proximity to the connecting circuit.

Abstract: An electrical circuit for measuring the shape of a voltage waveform in a print head of a printer is provided. The electrical circuit comprises an integrated circuit for generating one or more voltage amplitude waveforms. Further, the electrical circuit comprises an inkjet drop forming unit comprising a plurality of inkjet chambers, wherein each of the plurality of inkjet chambers comprises a piezoelectric actuator and an ink nozzle, and a connecting circuit between the integrated circuit and the inkjet drop forming unit suitable for applying one of the one or more voltage amplitude waveforms generated by the integrated circuit to the piezoelectric actuator in one of the plurality of inkjet chambers. In order to measure the shape of the one or more generated voltage amplitude waveforms via capacitive crosstalk, the electrical circuit also comprises a conductor in physical proximity to the connecting circuit.

Abstract: A method of operating a drop-on demand (DOD) jetting device having a nozzle, a pressure chamber filled with a liquid and connected to the nozzle and an actuator energized by a drive signal, wherein a periodic DOD signal determines whether or not a droplet is jetted out from the nozzle in a given DOD period, and the drive signal has a waveform configured to cause the actuator to excite a pressure wave in the liquid, the method further comprising the steps of a) energizing the actuator with a waveform that has a fixed pattern and extends over a time interval that is longer than the given DOD period; and b) ignoring the DOD signal in at least the first DOD period that follows after said period for which the step a) has been performed.

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 method is provided for cancelling an electric crosstalk contribution in a monitoring signal from a monitored electro-mechanical transducer in a device including at least three electro-mechanical transducers. The crosstalk contribution results from an actuation of other transducers than the monitored transducer. The method includes selecting a second transducer, associated with the first, monitored transducer, wherein the electric crosstalk caused by an actuation of a third transducer is equal in the first and second transducer; actuating the first transducer and not acutating the second transducer; simultaneously measuring a monitoring signal from the first transducer and the second transducer; and subtracting the two monitoring signals to obtain a clean monitoring signal from the first transducer.

Abstract: Fluid jetting device comprising: a nozzle plate, a fluid chamber terminating in an orifice in the nozzle plate, an actuator for generating a pressure wave in a fluid in the fluid chamber to jet fluid through the orifice from the chamber, a jetting waveform generating device connected to the actuator for generating an excitation waveform comprising two separated pulses, called a jetting pulse and a quenching pulse, for respectively generating a pressure wave in the fluid in the fluid chamber leading to a fluid droplet and for substantially cancelling a pressure wave in the fluid in the fluid chamber, wherein the jetting waveform generating device is adapted to make, when jetting two consecutive fluid droplets, a first and a second droplet, the jetting pulse of the second droplet at least partially overlap the quenching pulse directly following the jetting pulse of the first droplet.

Abstract: A method is provided for cancelling an electric crosstalk contribution in a monitoring signal from a monitored electro-mechanical transducer in a device including at least three electro-mechanical transducers. The crosstalk contribution results from an actuation of other transducers than the monitored transducer. The method includes selecting a second transducer, associated with the first, monitored transducer, wherein the electric crosstalk caused by an actuation of a third transducer is equal in the first and second transducer; actuating the first transducer and not acutating the second transducer; simultaneously measuring a monitoring signal from the first transducer and the second transducer; and subtracting the two monitoring signals to obtain a clean monitoring signal from the first transducer.

Abstract: A method of operating a drop-on demand (DOD) jetting device having a nozzle, a pressure chamber filled with a liquid and connected to the nozzle and an actuator energized by a drive signal, wherein a periodic DOD signal determines whether or not a droplet is jetted out from the nozzle in a given DOD period, and the drive signal has a waveform configured to cause the actuator to excite a pressure wave in the liquid, the method further comprising the steps of a) energizing the actuator with a waveform that has a fixed pattern and extends over a time interval that is longer than the given DOD period; and b) ignoring the DOD signal in at least the first DOD period that follows after said period for which the step a) has been performed.

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: Fluid jetting device comprising: a nozzle plate, a fluid chamber terminating in an orifice in the nozzle plate, an actuator for generating a pressure wave in a fluid in the fluid chamber to jet fluid through the orifice from the chamber, a jetting waveform generating device connected to the actuator for generating an excitation waveform comprising two separated pulses, called a jetting pulse and a quenching pulse, for respectively generating a pressure wave in the fluid in the fluid chamber leading to a fluid droplet and for substantially cancelling a pressure wave in the fluid in the fluid chamber, wherein the jetting waveform generating device is adapted to make, when jetting two consecutive fluid droplets, a first and a second droplet, the jetting pulse of the second droplet at least partially overlap the quenching pulse directly following the jetting pulse of the first droplet.

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: 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: 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.

Abstract: An inkjet printing apparatus includes a print head having an ink duct, a piezoelectric element operatively coupled to the ink duct, and a control device for controlling an ink drop ejection from the ink duct by actuation of the piezoelectric element. The control device includes a current source, a number of power supplies, and a switch, connected between the current source and the number of power supplies. The current source is configured to generate a current for actuating the piezoelectric element by charging and discharging. The switch is configured to connect the current source and one of the number of power supplies. The one of the number of power supplies is selected such that a lowest voltage difference over the current source exists.

Abstract: A method obtains an image from multiple ink droplets transferred to a receiving substrate using an ink jet printer including a plurality of ink chambers operatively filled with ink. Each ink chamber has a nozzle and a corresponding transducer. The ink chambers have mutually distinguishable acoustics. The method includes, for the respective ink chambers, generating an electrical pulse, applying the pulse to the transducer corresponding to a respective ink chamber in order to generate a pressure wave in the ink, such that a droplet of the ink is jetted out of the nozzle having a size corresponding to the pressure wave, and adjusting the pulse to the acoustics of the respective ink chamber such that the size of the droplet which is jetted is essentially the same for each ink chamber. A printer is configured for application of the method.

Abstract: A method obtains an image from multiple ink droplets transferred to a receiving substrate using an ink jet printer including a plurality of ink chambers operatively filled with ink. Each ink chamber has a nozzle and a corresponding transducer. The ink chambers have mutually distinguishable acoustics. The method includes, for the respective ink chambers, generating an electrical pulse, applying the pulse to the transducer corresponding to a respective ink chamber in order to generate a pressure wave in the ink, such that a droplet of the ink is jetted out of the nozzle at a speed corresponding to the pressure wave, and adjusting the pulse to the acoustics of the respective ink chamber such that the speed at which the droplet is jetted is essentially the same for each ink chamber. A printer is configured for application of the method.

Abstract: A method and apparatus for obtaining an image consisting of multiple ink droplets placed at a plurality of locations on a receiving substrate, using an inkjet printer containing an ink chamber having an ink droplet ejection site, and a transducer operatively associated with said chamber, wherein each of the ink droplets, determining a desired accuracy of placement of the droplet on the substrate, the accuracy corresponding to the speed at which the droplet is jetted from the chamber, generating an electrical pulse corresponding to the said speed of the droplet, and applying an electrical pulse to the transducer in order to provide a pressure wave in the ink chamber whereby the ink droplet is ejected from the chamber essentially at said speed.

Abstract: A method and device for detecting, in a printer or scanner, the position of a carriage moving along a codestrip provided with a sequence of position marks. Sensors mounted on the carriage generate a detection signal each time that they detect an individual position mark, the timings of the detection signals are measured, and basic position information regarding the carriage is determined on the basis of these timings. Two sensors are arranged on the carriage at a predetermined distance, L, from one another in the direction of movement. The basic position information, derived from the timings of the detection signals from both sensors, is then calibrated on the basis of the distance, L, between the two sensors.

Abstract: The invention relates to a synthetic resin composition comprising a phenol-formaldehyde resin and a polyurethane component, and to a substrate material for printed circuit boards, comprising a fibrous carrier material which is impregnated with such a synthetic resin composition derived from the reaction of a phenol and a formaldehyde-producing compound in the presence of the polyurethane component and a basic catalyst to form an interpolymer which upon further processing yields a substrate material which is on the one hand suitable to be provided with holes by punching and piercing and on the other is not subject to an objectionable degree of sagging during the soldering of components onto the printed circuit board by means of a wavesoldering bath.

Abstract: The present amplifier is designed in such a way that the amplifier will exhibit a linear characteristic in response to small variations of the input signal and a hard switching characteristic in response to large variations of that input signal. Due to the design of this amplifier, the output signal will generally be proportional to the input signal, but will be able to respond more quickly to a sudden increase of the input signal. The present amplifier is particularly useful in an amplifying circuit of a videoamplifier.