| 摘要 |
PURPOSE:To facilitate adjusting operation and to qualify density control by forming a reference image for toner supply control in either of reversal or normal development modes. CONSTITUTION:The surface potential of a photosensitive drum 1 is made negative by an electrostatic charger 2 in both reversal developing operation and normal developing operation. Therefore, the negative potential of the drum 1 is erased by the exposure of a light emitting element in either case when a reference image formation area passes through an eraser 8. Then, a formed reference latent image is developed on a reversal basis by a developing device 4 wherein a negative bias is applied to the developing sleeve 42 to obtain the reference image. The reflection density of this image is detected by a light emitting element 9a and a photodetecting element 9b and compared with a reference value to supply toner. This operation is not always in the reversal development mode and may be in the normal development mode. consequently, the equipment adjustment is facilitated and the density control is qualified. |
