| 摘要 |
PURPOSE:To obtain a picture of high picture quality having high resolution by comparing a toner image on a pseudo original and the pseudo original and adjusting the bias potential or exposure of a developing roll based on the calculated value of a change in the bias potential or exposure corresponding to a difference between both the images. CONSTITUTION:A pseudo original 13 obtained by arranging thin line 13a and ground parts 13b alternately and continuously is used, the pseudo original 13 is scanned by exposure to form a toner image T on a photosensitive drum 7, the state of the image is compared with the state of the pseudo original 13, and bias voltage is set up based on the compared result, so that adjustment considering the comparison between the thin line parts 13a and the ground parts 13b can be attained. In case of copying an original such as a character original including complex KANJI (Chinese characters) in which thin lines and ground parts are thickly arranged, the method can copy images with high reproducibility and high resolution as compared to a method for simply checking the density of black ground. Thus, an image of high picture quality with high resolution can be obtained. |
