| 摘要 |
PURPOSE:To obtain a correct copy by comparing the output signal of the large area of an original with that of its small area after correction of the areas, and controlling the image density in accordance with that higher output signal. CONSTITUTION:A photodetector 22A for detecting a state of the large area of an original, and plural photodetectors 22B for detecting states of its small areas are arranged, and the output (a) of the detector 22A is compared with those (b) of the detectors 22B after correction of the areas. The comparison of both outputs is executed by calculating a'/b or b'/a, where a'=aXSB/SA, b'=bXSA/SB, SA, SB are the area of the original of light incident to the photodetector 22A, and those of the lights incident to those 22B, respectively. When the detector 22B detects lines or a fold, misjudging it as the background of the original can be prevented by detecting its larger area and complementing it. On the other hand, if only the larger area is detected, since the reflected light amt. depends upon the amt. of printed characters, the smaller areas are detected and when the output of the smaller area is lower than that of the larger area, it is judges as misdetection, and priority is given to the output signal of the detector 22a. |
