Electrostatic image forming apparatus capable of reducing defective image transfer caused by free toner particles deposited on a corona discharger

摘要

In an electrostatic image forming apparatus, including a corona discharger located so as to face an image carrier on which a toner image is to be formed. When a paper or similar recording medium is brought between the image carrier and the discharger, the discharger effects corona discharge at the rear of the recording medium so as to charge the medium to a polarity opposite to the polarity of the toner image. The toner image is then transferred from the image carrier to the recording medium. A polarity switcher allows a voltage of substantially the same polarity as the toner to be applied to a discharge wire included in the discharger, and environmental sensing device allows this voltage to be changed based on temperature and humidity conditions. The apparatus is free from defective discharge and defective image transfer ascribable to the deposition of free or isolated toner on the discharger.