| 摘要 |
PROBLEM TO BE SOLVED: To eliminate unnecessary toner consumption caused by standard patch, contamination of a transfer machine and static eliminator and burden on a cleaning device by controlling the value of a developing bias impressed upon a developing means to an electric potential where a latent image of the prepared standard patch is not developed when the standard patch passes through the developing means. SOLUTION: A developing device 13, which is a developing means, develops electrostatic latent image on a photosensitive body drum 10 formed by charging by a scorotron charger 11 and image exposure by an exposure unit 12 by reversal by means of a toner (here, it is minus polar toner) of charged polarity and homopolarity under non-contacting condition caused by a non-contacting developing method effected by impression of developing bias voltage. If the value of the developing bias is set to a minimum charged potential of a image exposure portion irradiated by a maximum exposure quantity, for example, to 190V- an absolute value being less than 200V by 10V - when a standard patch EP pass through the developing device 13, it results in not developing the standard patch portion. |
