| 摘要 |
An image forming apparatus can effectively restrict a phenomenon to lower a charge amount of toner on a developing roller according to increasing of number of printing to stabilize supply of toner for a latent image carrier body and whereby to maintain good printing condition for a long period. The image forming apparatus includes a latent image carrier body, a developing roller supplying a toner to a latent image formed on the latent image carrier body, a toner supply roller supply the toner contacting the developing roller, a thin film forming member restricting a toner amount and a toner charge amount on the developing roller contacting with the developing roller, and power source means for supplying a bias to the toner supply roller and the thin film forming member in such a manner that a relationship between a voltage Vsr and a current Isr satisfies |Vsr|/a+|Isr|/b=1 (where a and b are constants of power source characteristics).
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