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 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: 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 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.