| 摘要 |
PROBLEM TO BE SOLVED: To obtain correct registration by correcting improper timing of the receiving of a control signal and displacement of scan/light emission in an exposure unit. SOLUTION: On the underside of a document scale 19, an identification pattern 23 is provided. Also, in the middle of the document carrying belt 22 of an ADF(automatic document feeder), an identification band 24 is provided. A document D (not illustrated) is so set as to be butted against the scale 19, and it is subjected to exposure. On a photoreceptor, the latent image of the identification pattern 23 (the latent image of the identification band 24 as well in the case the document is set apart from the scale 19) is formed at the front end of the latent image of the document D. Then, the potential of each latent image is detected by a surface-potential meter, and the position of the front end of the document is judged. Based on the position of the front end of the document, the timing of the redriving of a registration roller is computed. |
