Color printer with a controller and a printing station for each color

A color printing unit, comprising:

• one printing station for each color;
• one anode roller per printing station;
• a continuous transfer belt covering the anode rollers and guided over a deflection roller and a control roller;
• one of more sensors for measuring properties of reference markings printed on the transfer belt;
• and
• a control device for controlling and adjusting straight travel of the transfer belt by an actuating motor acting on the control roller as a function of the measured properties of the reference markings,
• wherein the one of more sensors are arranged in an area of the control roller for the transfer belt,
• wherein the control roller can be deflected in an X and Y direction via the actuating motor, and
• wherein, during the measurement, at least for a period during which the printed reference markings pass under the one or more sensors, relative movements between the one or more sensors and the control roller are ruled out.