| 摘要 |
PURPOSE:To prevent erroneous stripping of paper and to improve reliability by detecting the density of an original and stopping copying operation before the paper is stripped from a photosensitive body by a corona charger when the density exceeds a prescribed value for prescribed time. CONSTITUTION:This machine is provided with a photodetector, for example, a photodiode 30 for converting light to an electrical signal in the optical path from an original to a photosensitive body 10, detects the density of the original by said photodetector and controls the density by the output therefrom. The output from a differential amplifier 33 attains a high level when the quantity of the light detected by the photodiode 30 is below the prescribed level and said output attains a low level when the quantity of the detected light exceeds the prescribed level. A CPU36 upon receiving said output judges that the original is solid black or other and stops the copying operation and performs simultaneously jam display, etc. if the output from the differential amplifier 33 remains at the high level form the prescribed time (within the time when paper P arrives at a stripping point from an exposing point) since an exposing lamp 4 is lighted. |
