A developing device with a roller with a rough surface and a developer with additive particle size corresponding to one of the surface structure

摘要

A developing device according to the present invention comprises an image developing roll 4 having a roll surface treated with sand blast treatment to form a rough surface morphology in which aluminum anodizing is also applied to the surface of the image developing roll 4 where the rough surface morphology is formed. To the image developing roll 4 is applied a development bias consisting of a direct current voltage overlapped with an alternate current voltage. In this arrangement, the image developing roll 4 can perform the functions of conveying developer, charging developer, and preventing of discharge of the developing bias, while the image developing roll 4 can be manufactured from a metallic roll such as aluminum roll at a low cost. Moreover, a gradual scraping of the image developing roll 4 surface by external additives of toner 3 suppresses adhering of toner 3 onto the surface of the image developing roll 4, preventing the occurrence of filming.