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 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 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 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 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 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 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 print group for an ink printing apparatus, a housing is provided with print bars comprising print heads. The print bars are moveable independently of one another in a vertical direction from a printing position adjacent to a printing substrate into a park position and back. A protective flap bar for each print bar is provided which is pivotable and which is open to one side. The protective flap bar is arranged in a vertical position next to the print bar in the printing position such that the open side is facing away from the print bar. The protective flap bar is arranged in a horizontal position with the open side upward in the park position such that the print bar is engaged with its print head side in the protective flap bar.

Abstract: In a method to execute a print interruption, a printing substrate is printed to with a printing unit with at least one print head. With aid of a sensor, print clock pulses are generated that are supplied to a print controller depending on a feed of the printing substrate. With triggering of the print interruption, a feed speed of the printing substrate is reduced from a print speed in the printing operation to a predetermined speed according to a deceleration ramp. After the print interruption the printing substrate is accelerated again to the print speed according to an acceleration ramp. Given occurrence of a print clock pulse during at least one of the ramps, the print controller sends at least one vibration pulse to the at least one print head so that at least one cycle of vibration oscillations is implemented at the print head. The at least one vibration pulse is generated if a time interval of the print clock pulses relative to one another reaches a predetermined value.

Abstract: In a digital printer a developer element is provided that inks charge images on a charge image carrier with toner. A feed system is provided to apply liquid developer with the toner onto the developer element. The cleaning unit is provided with a cleaning element to clean off residual liquid developer remaining on the developer element after the development of the charge images. A scraping unit rests on the cleaning element made up of a double blade arranged in a blade mount. The double blade provides a cleaning blade and a sealing blade that together form a blade chamber that is filled with fluid. The cleaning blade has at least one row of holes adjacent to a blade edge of the cleaning blade.