Patent ID: 6829448
Filing Date: 2004-12-07
Classification: G03G

Abstract:
An image forming apparatus having a hybrid developing apparatus comprising a magnetic roll of two components developer material, which electrostatically charges developer material consisting of carrier and toner magnetically held thereon, and a developing roll, which forms an only toner thin layer on its surface by transferring the toner from the magnetic roll wherein latent images on a latent image bearing body are developed with the toner by applying developing bias to nearest approached regions (developing regions) between the developing roll and the latent image bearing body, characterized in that a developing roll, which is electrically conductive at least on its surface, is directly confronted with a latent image bearing body through an insulative toner thin layer, and that a developing bias is applied to the electrically conductive surface of the developing roll, forming a continuous plane of electrode, and the entire developing roll is electrically conductive and an alternating current bias superposed by a direct current bias thereon is applied onto the developing roll to draw back toner from the latent image carrying body to the developing roll, and wherein a duty ratio of the alternating current bias is set as within the range from 10 to 50%.