Patent ID: 7136599

Claim:
A developing apparatus comprising: a development member for developing an electrostatic latent image on an image carrier by applying one-component non-magnetic toner, the development member being in contact with the image carrier; a regulating member for regulating thickness of toner layer on the development member; and a voltage applier for applying bias voltage to a portion between the development member and the image carrier, the bias voltage oscillating between voltages V 1 and V 2 , wherein voltage V 1 satisfies all of conditions (1) through (3), and voltages V 1 and VH exhibit homopolarity with reference to voltage Vg,  VH - Vg  <  V1 - Vg  ( 1 ) 350 ⁢ ⁢ V ≦  V1 - VL  ≦ 500 ⁢ ⁢ V ( 2 ) VH - 200 ⁢ ⁢ V ≦ V1 ⁢ ⁢ ( in ⁢ ⁢ case ⁢ ⁢ VH < 0 ) V1 ≦ VH + 200 ⁢ ⁢ V ⁢ ⁢ ( in ⁢ ⁢ case ⁢ ⁢ VH > 0 ) } ( 3 ) voltage V 2 satisfies both conditions (4) and (5), and voltages V 2 and V 1 exhibit antipolarity with reference to voltage VL, 70 ⁢ ⁢ V ≦  V2 - VL  ≦ 150 ⁢ ⁢ V ( 4 ) V2 ≦ VH + 500 ⁢ ⁢ V ⁢ ⁢ ( in ⁢ ⁢ case ⁢ ⁢ VH < 0 ) VH - 500 ⁢ ⁢ V ≦ V2 ⁢ ⁢ ( in ⁢ ⁢ case ⁢ ⁢ VH > 0 ) } ( 5 ) and above notations represent Vg: ground voltage, VH: voltage of a background section in an electrostatic latent image formed on the image carrier, and VL: voltage of a visible section in an electrostatic latent image formed on the image carrier, VL and VH exhibit homopolarity with reference to Vg, and a condition |VL−Vg|<|VH−Vg| is satisfied.