Color image forming apparatus by direct printing method with flying toner

Abstract

A color image forming apparatus includes development rollers, aligned in the transport direction of recording paper, for carrying toner of respective colors charged in a predetermined polarity. A driver substrate having a plurality of toner passing holes in locations facing the development rollers is installed. Control electrodes are mounted around the toner passing holes. A back electrode is mounted opposite to the driver substrate so that the recording paper passes through a section between the back electrode and the driver substrate. A voltage whose polarity is opposite to the toner is applied to the back electrode, while either a first voltage or a second voltage is selectively applied to the control electrode according to an image signal. The first voltage allows the passage of toner through the toner passing holes. The second voltage prevents the passage of the toner. Both the first and second voltages to be applied to the control electrode have the same polarity as the toner. This structure prevents adhesion of the toner to the control electrode, thereby obtaining a quality image.