Sanyo Electric Co., Ltd.

Masato Sone

Motoaki Mushika

Masayuki Tanaka

Yasuhiro Kishimoto

An image forming apparatus includes a microcomputer which increments a mode counter each time a copying operation is completed in a selected one of a non-inverted or inverted image forming mode. After the completion of the copying operation in the selected mode, when the image forming mode is changed to the other image forming mode, a time is set in a timer according to the count value of the previously used selected image forming mode counter and a photosensitive drum is pre-charged to a predetermined voltage corresponding to the image forming mode to be utilized next. Therefore, a pre-charge time can be set for one of the inverted and non-inverted image forming modes in accordance with the number of image forming operations carried out in the preceding selected image forming mode. The transfer corona producing source of the apparatus can be used as the pre-charging voltage source when the inverted image forming mode is selected and the main corona producing source can be used when the non-inverted image mode is selected.

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Gifu, Japan

Masato Sone