Method of multicolor electrophotographic printing with unipolar toner

A method for electrophotographic printing of a print image with a plurality of colors on a carrier, comprising the steps of:

• providing the print image with
• at least a first image element having a color of the carrier,
• at least one second image element having a second color,
• at least one third image element having a third color, and
• at least one further image element having a further color,
• providing a photo conductor layer and an electrode layer carrying a predetermined reference potential are contained in a layer system,
• allocating a first surface element of the photo conductor layer to the first image element,
• allocating a second surface element of the photo conductor layer to the second image element,
• allocating a third surface element of the photo conductor layer to the third image element,
• allocating a further surface element of the photo conductor layer to the further image element,
• charging the first and second and third and further surface elements to a starting potential of a first polarity;
• differently illuminating the surface elements such that the second surface element has a second potential and the third surface element has a third potential, the second potential being higher in amount compared to the third potential and the further surface element has a further potential that is higher in amount compared to the second potential and the first surface element has a first potential that is higher in terms of amount compared to the further potential following illumination;
• developing the surface elements with color particles of the third color including depositing color particles of the first polarity and of the third color on the third surface element upon employment of a first auxiliary electrode that has a first auxiliary potential that is higher in terms of amount than a momentary potential on the third surface element and lower in terms of amount than a momentary potential on the second surface element;
• arranging the surface elements close to a means for increasing potential so that the potential on the third surface element is increased in terms of amount after application of the color particles of the third color,
• arranging the surface elements close to a light source having an approximately uniform light distribution so that the third surface element covered with color particles is illuminated substantially less than the first surface element which is free of covering by color particles and the further surface element which is free of covering by color particles and the second surface element which is free of covering by surface particles which causes a momentary potential on the second surface element to be reduced in terms of amount to a potential that is lower in terms of amount than a momentary potential on the third surface element;
• developing the surface elements with color particles of the second color by depositing charged color particles of the first polarity and of the second color on the second surface element upon employment of a second auxiliary electrode that has a second auxiliary potential that is higher in terms of amount than a momentary potential on the second surface element and lower in terms of amount than a momentary potential on the third surface element and a momentary potential on the first surface element;
• arranging the surface elements close to a further means for increasing potential to cause the potential on the second surface element to be increased in terms of amount after application of the color particles of the second color;
• arranging the surface elements close to a further light source so that the further surface element which is free of covering by color particles is respectively considerably more illuminated that surface elements covered with color particles which causes the potential on the further surface element to be reduced in terms of amount to a potential that is lower in amount than a momentary potential on the second surface element;
• and
• developing the surface elements with color particles of the further color so that color particles of the first polarity and of the further color are deposited on the further surface element upon employment of a further auxiliary electrode that has a further auxiliary potential that is higher in amount than a momentary potential on the further surface element and lower in amount than momentary potentials on other of the surface elements.