Developing apparatus using one-component toner

摘要

An object of the present invention is to prevent an electrical breakdown of a toner layer and an occurrence of overcurrent, thereby preventing quality of image from being degraded at the time of development, when development with one-component toner is conducted using a developing roller of low resistance. The resistance value Rd of a developing roller (41) which carries and conveys one-component toner (10) in a manner of coming into contact with a photoconductor (1) which bears an electrostatic latent image, is defined as Rd = rho d . (Dd1/S1), wherein S1 (cm<2>) is an area in which the developing roller (41) comes into contact with the static image bearing member via a toner layer (45), Dd1 (cm) is a layer thickness of a semiconductive layer which composes the developing roller, and rho d ( OMEGA . cm) is a volume resistivity thereof. The range of the resistance Rd is set as 10<4> < Rd < 10<5> and the resistance Rt ( OMEGA ) of the toner layer is set as Rt > 5 x 10<7>. By using the developing roller (41) of low resistance, excellent development is realized and an electrical breakdown and an overcurrent can be avoided by the resistance value of the toner layer. <IMAGE>