Method for operating an image-forming device and an image forming device for application of the method

A method for operating an image-forming device, the image-forming device comprising:

• an image-recording medium;
• a toner supply roller arranged for supplying toner particles to the image-recording medium;
• a developing element comprising a rotatable sleeve and an internal stationary magnet system generating a first magnetic field;
• and a cleaning magnet system, configured to provide an activatable second magnetic field,
• the image-forming device being operable in a printing mode wherein the toner supply roller supplies toner particles to the image-recording medium, the rotatable sleeve rotates in a first direction so as to form a toner assembly in a developing zone by an interaction between the magnetically attractable toner particles and the first magnetic field generated by the stationary magnet system, while removing excessive toner and transporting the same back to the toner supply roller, and
• the image-recording medium forms a toner image on the image-recording medium in the developing zone by selectively electrically attracting toner particles onto the image-recording medium in accordance with a digital image pattern,
• the method comprising a step of switching the image-forming device into a cleaning mode, the cleaning mode comprising:
• stopping the toner supply to the image-recording medium;
• rotating the rotatable sleeve in a second direction, opposite to the first direction, such that the magnetically attractable toner particles are transported out of the developing zone towards the cleaning magnet system;
• and
• activating said second magnetic field so as to remove the transported magnetically attractable toner particles from the rotating sleeve of the developing element.