NON-MAGNETIC ONE-COMPONENT DEVELOPING DEVICE

摘要

PROBLEM TO BE SOLVED: To eliminate the lowering of the density not only at the trailing edge of an image but also at the leading edge of the image by controlling a switching means between image forming time when an electrostatic latent image is made visualizable and image non-forming time when the latent image is not made visualizable. SOLUTION: A toner supply roller 6 is obtained by forming a conductive foaming body around a metallic shaft 6a and toner supply bias power sources 25a and 25b are connected to the shaft 6a through a toner supply bias switching means 26. Thus, a toner supply bias value is different from the image forming time and the image non-forming time is impressed. When it is assumed that developing bias voltage impressed on a developing roller 5 is VB and toner supply bias voltage is VSR, VB and VSR have the same polarity, and they satisfy the relation of |VB|<|VSR| at the image forming time and satisfy the relation of |VB|>|VSR| at the image non-forming time, or VB and VSR have the same polarity and satisfy the relation of |VB|<|VSR| at the image forming time and VB and VSR have the reverse polarity at the image non-forming time.