| 摘要 |
PROBLEM TO BE SOLVED: To provide a developing device where electrified charge amount of toner carried on a developing roll can be maintained high and an image with a superior gradation can be obtained even when contact developing is carried out and to provide an image forming device, etc. SOLUTION: In the developing device 4, a developing roll 5 brought into contact with a photoreceptor drum 1 and an elastic blade 7, etc., brought into contact with the roller 5 are provided in a developing container 14 storing a non magnetic toner 8 of negative polarity consisting of one component developer and the DC contact developing method where developing bias of DC voltage from a power source 18 is impressed on the developing roll 5 is adopted. An electrifying roll 20 that is in contact with the developing roll 5 is provided downstream of the blade 7 to further make electrified amount of the toner 8 on the developing roll 5 greater after a layer thickness restriction and electrifying is applied to the toner 8 on the developing roller 5 by the blade 7, electrifying bias of -1700 V is applied to the roll 20 and the toner 8 on the developing roll 5 is electrified at a potential difference of 1500 V from -200 V DC voltage of the developing bias. |
