Abstract: A printing unit prints to a pre-folded substrate web. An intake unit is at an intake of a transport arrangement. A synchronization sensor is at the transport arrangement between an infeed roller and the printing unit. The synchronization sensor emits a synchronization signal when a fold of the web is present at the synchronization sensor for synchronization of a printing operation with feed of the web. A path between the synchronization sensor and a freely accessible point of the intake unit is designed such that a fold is present at the synchronization sensor when the printing substrate web has a fold at the accessible point. A relative humidity sensor is at the printing unit. A relative humidity measured by the sensor is compared with a relative humidity of an input stack. Given a deviation a length change of the web between the synchronization sensor and the accessible point is calculated, the web being displaced by the length change at the accessible point.

Abstract: In a method or system for processing a color print image for digital printing at a predetermined printing apparatus, the print image is deconstructed into color separations according to characteristic color curves of the printing apparatus. The color separations are stored in a data unit as greyscale bitmap images and at least one of a color code and color values are associated with each color separation in the data unit. The print image encoded in the data unit is presented at a display device for monitoring or management before printout at the printing apparatus, the print image being presented at the display device by means of at least one of the color code and color values associated with the respective color separations such that the individual color separations are transparently superimposed.

Abstract: A digital printer has at least one print group with a station to generate charge images of images to be printed on a charge image carrier, the station having a developer station to ink the charge images using liquid carrier having toner and carrier fluid. The developer station comprises a rotating application unit that transports the liquid developer to the charge image carrier. The feed system feeds the liquid developer to the application unit. The dosing unit adjacent to the application unit and after the feed system comprises a dosing roller and an elastic unit acting on the dosing roller, the elastic unit exerting an adjustable contact pressure force on the dosing roller in a direction of the application unit.

Abstract: In a digital printer, print groups are provided each having a respective developer station using liquid developer comprising carrier fluid and toner. A supply arrangement to supply the print groups is provided with fluids and to accept used and unconsumed fluids from the print groups. The supply arrangement has a first supply unit common to all print groups to supply the print groups with the fluids, at least one reservoir containing a carrier fluid. A second supply unit per color supplies the respective print group for the color with liquid developer. The second supply unit comprises a first buffer container connected with a reservoir, the reservoir containing carrier fluid and concentrated toner as toner concentrate. A second buffer container for carrier fluid is connected with the carrier fluid reservoir in the first supply unit.

Abstract: In a method to execute a printing interruption in a printing operation, with aid of a sensor, print clock pulses are generated which are supplied to a print controller depending on a feed speed of the printing substrate web. With triggering of the print interruption the feed speed of the printing substrate is reduced from a print speed to a predetermined speed in a slowing ramp, and after the print interruption the printing substrate is accelerated again to the print speed in an acceleration ramp. With aid of the sensor, print clock pulses are generated which are supplied to a print controller depending on the feed speed of the printing substrate. Given occurrence of a print clock pulse during the ramps, with the print controller a vibration cycle is initiated at nozzles of the print head that are not ejecting ink droplets at a time when the vibration cycle is initiated.

Abstract: In a method to clean nozzles and ink channels of at least one ink print head with a flushing medium in an ink printing apparatus, a necessary flushing quantity of the flushing medium that is to be provided and which is necessary for flushing of the ink print head in a flushing process is determined from either a predetermined flushing quantity predetermined depending on a print duration of the ink printing apparatus or from a drive flushing quantity derived from a flushing quantity curve that indicates a dependency of the flushing quantity on an elapsed time for an ink used in printing, the necessary flushing quantity being either said predetermined flushing quantity or the derived flushing quantity, whichever is greater. The determined necessary flushing quantity is used to flush the ink print head.

Abstract: In a method to control printing elements of an ink print head for ejection of a respective ink droplet, respective control voltages are applied to activators of the printing elements. The control voltages comprise at least one vibration voltage pulse that induces at least one vibration oscillation in the associated printing element, and an associated print dot voltage pulse that induces an ejection of the respective ink droplet by the associated printing element. The at least one vibration voltage pulse is chronologically arranged before the associated print dot voltage pulse, and an amplitude of the at least one vibration voltage pulse is respectively chosen depending on a size of the respective ink droplet to be subsequently emitted by the respective printing element.

Abstract: In a method to determine particle mass concentration in a dispersion having particles and fluid, the dispersion in a measurement cell is exposed to an alternating field of variable frequency to set the particles into oscillation to generate sound pressure waves. Amplitudes of the sound pressure waves are measured depending on the frequency so that a maximum amplitude of the sound pressure waves is established and a frequency associated with the amplitude is determined as a resonance frequency of the sound pressure wave. The mass concentration of the particles in the dispersion is established from the resonance frequency.

Abstract: In an arrangement to supply ink to a print head unit having a print head, an input, and an output, a back-pressure tank having ink is provided and connected with the input of the print head unit. A degassing unit for ink and having an input and an output is also provided. A first selector valve is connected to the degassing unit input, the first selector valve in a first position establishing a connection of the degassing unit with the output of the print head unit. A second selector valve is connected to the degassing unit output, the second selector valve in a first position establishing a connection of the degassing unit with the back-pressure tank.

Abstract: In a method to output document data divided into pages at an output printing apparatus, a print file encoded in a page description language is provided with per-page variable document data and bin command data, the bin command data referring to at least one page input tray of a reference printing apparatus for page-shaped recording material. The page input tray is provided to accept form pages with at least one pre-print image. At least one macro data set is created that contains a group of commands of the page description language and pre-print image data with which the pre-print image can be reproduced as a rastered image. Association data are generated for an association between the bin command data and the macro data set. The print file is sent as a data stream from a document data computer to a controller. In the controller the variable document data are merged and rastered with the pre-print image data using the bin command data and the association data.

Abstract: In a method to adjust hue of a print images by toner layer thickness a photoconductor element is charged to a charge potential. A potential image of the print image made up of image points is generated via exposure and discharge of the photoconductor element. The potential image is inked by charged toner via a developer element at a BIAS potential. With a character generator, generating a potential of an individual image point of the print image via local discharge of the photoconductor element, the potential of the image point lying between the BIAS potential and a potential established by a maximum achievable discharge depth of the photoconductor element, and so that the individual image points have same or different potentials, depending on the exposure, so that the exposed area overall has a resulting potential, and a depositing of toner on this area and therefore the toner layer thickness on this area is proportional to the resulting potential.

Abstract: In a method or system to operate a digital printer for double-side printing to a recording medium with toner particles applied with a liquid developer, the digital printer prints first and second sides of the recording medium in succession. Electrophoretic mobility of toner particles of a first toner image on the first side is reduced after application of said first toner image and before application of the second toner image on the second side of the recording medium. The electrophoretic mobility is reduced by drying the first toner image along a drying route in an airflow generated by a blower such that carrier fluid is thus removed from the first toner image. After the application of the second toner image on the second side of the recording medium, both the first and second toner images are simultaneously fixed.

Abstract: In a method to execute a printing interruption in a printing operation of an ink printing system in which a printing substrate is printed with at least one print head during the printing interruption in which a feed speed of the printing substrate web comes to a standstill, at least one vibration pulse is sent to the at least one print head to trigger vibration oscillations before a print controller loads print data into the at least one print head. Thereafter a print-start signal is sent to the at least one print head.

Abstract: In a digital printer comprising a developer station using liquid developer, the developer station has an application unit via which liquid developer is transported to a charge image carrier. The supply system adjacent and lateral to the application unit supplies liquid developer to the application unit. A pre-chamber and an electrode segment are provided, the pre-chamber being filled with liquid developer and open towards the application unit. The pre-chamber is open at a top such that a compensation volume of liquid developer with an open surface is created past which the application unit passes. The electrode segment is arranged adjacent to the pre-chamber and to a side of the application unit such that it forms a gap with the application unit through which the liquid developer is directed, the electrode segment being at an electrical potential such that toner of the liquid developer transfers to the application unit in the gap.

Abstract: In a method or digital printer to print a recording material with toner particles applied with a liquid developer, toner concentration of the liquid developer is determined via measurement with aid of ultrasonic pulses. At least one ultrasonic pulse is generated by discharging an ultrasound emitter charged with a charge voltage. The ultrasonic pulse permeates the liquid developer and is received by an ultrasound receiver which generates a reception signal corresponding to the received ultrasonic pulse. With a control device, the charge voltage is regulated to a value such that a representative value of the reception signal corresponds to a predetermined desired value. The toner concentration is determined from the regulated charge voltage.

Abstract: When cleaning inkjet print heads, a first cleaning fluid is provided which includes at least one cellulase or a catalytically active derivative thereof. A contaminated and/or blocked inkjet print head (12) is cleaned using this first cleaning fluid.

Abstract: In a method to execute a pause function in an inkjet printing system with at least one printing apparatus, the pause function is triggered to reduce a feed speed of the printing substrate web from a speed during printing operation to a predetermined speed for a predetermined duration. The duration is selected so that the printing substrate has suitable properties with regard to at least one of the elements selected from the group consisting of moisture and temperature under the printing unit of the printing apparatus at an end of the pause function. After ending the pause function, the printing substrate web is accelerated again to the speed during the printing operation.

Abstract: In a method to operate an inkjet printer with at least one first and one second printing station to print to a continuous recording medium, and wherein a drying device is provided for drying the recording medium that is printed to in the first printing station, the drying device being in a region between the first and second printing stations, after a halt of the recording medium which is equal to or greater than a predetermined duration, removing the print heads of the second printing station out of a printing position from the transport path into a park position, and after the startup only directing the print heads back again into the printing position if a segment of the recording medium that was located in a region before the drying device during the halt has passed the print heads of the second printing station.

Abstract: In an arrangement to supply ink to a print head unit having a print head, an input, and an output, a back-pressure tank having ink is provided and connected with the input of the print head unit. A degassing unit for ink and having an input and an output is also provided. A first selector valve is connected to the degassing unit input, the first selector valve in a first position establishing a connection of the degassing unit with the output of the print head unit. A second selector valve is connected to the degassing unit output, the second selector valve in a first position establishing a connection of the degassing unit with the back-pressure tank.

Abstract: In a method or system for printing of a recording medium, potential images of images to be printed are generated on a potential image carrier. The potential images are developed into an image film comprising image regions and non-image regions on the potential image carrier via application of a liquid developer comprising a polymerizable carrier fluid with dye particles suspended therein. The image film is transferred onto the recording medium. The image film is fixed on the recording medium via a cross-linking reaction of the carrier fluid such that the dye particles of the image regions are embedded in a fixed polymer matrix and the carrier fluid hardens into a transparent film that permanently bonds with the recording medium. The cross-linking reaction of the carrier fluid is started, accelerated, or extended by at least one component.