| 摘要 |
PURPOSE:To prevent the solid development of a part which need not be copied by cutting off image exposure light from said copy unnecessary part in negative- to-positive copying operation and guiding erasure light from an erasure light source to the upper part of the surface of a photosensitive body corresponding to the copy unnecessary part in positive-to-positive copying when a partial copy is taken. CONSTITUTION:When a positive-to-positive copy is taken, the erasure light source 19 is turned on for slit exposure and the erasure light 19a is guided to a non-copy part on the drum 1 to remove the potential of the non-copy part, thereby taking a partial copy. When a negative-to-positive copy is taken, on the other hand, the erasure light source 19 is not turned on and an exposed part is only controlled to perform necessary partial copying operation. Consequently, unnecessary solid development is not performed between non-image parts or image parts without any discrimination among entire-surface copying, partial copying, negative-positive copying, and positive-positive copying.
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