| 摘要 |
PURPOSE:To obtain a good copy image by detecting optically the density of the toner image obtd. by exposing a document onto a photosensitive body in the stage of scanning before exposure and developing the image thereof, comparing the detected output with a reference voltage and controlling the surface potential of the photosensitive body according to the result of the comparison. CONSTITUTION:The document on a document plate 1 is irradiated by an exposing lamp 2. An electrostatic charger 12, a developing part 13 and an electrostatic charger 15 for transfer are successively provided around the photosensitive body 11. A means for detecting the density of the document image consisting of a light emitting diode 16 and a phototransistor 17 is provided near the charger 15. The body 11 is exposed by the reflected light from the document in the stage of scanning before exposure and is then developed. Part of the varied densities of the resulted toner image is detected by the means for detecting the density of the document image. The detected output is compared with the reference voltage and the surface potential of the body 11 is controlled according to the result of the comparison. The good image having no ground stain is thus copied. |
