| 摘要 |
PURPOSE:To prevent the damage of document and to eliminate the waste in an operating time by installing a left document detection means for detecting whether or not the document is left and an informing means for displaying the effect. CONSTITUTION:The density detecting sensor for the document possesses spectral characteristic approximate to drum sensitivity characteristic and detects the density of the surface of the document in a document reflection level. A size detecting sensor, on the other hand, detects difference between a conveying belt whose reflectance is low and the document whose reflectance is comparatively high in a short wavelength band in which the drum sensitivity is low. Thus, the existence of the document can be judged according to output values and output difference from both sensors. If the document is left, the display of warning such as lighting a lamp, flickering and the output of a buzzer tone, etc., is executed on an operation display part. Thus, the document can be prevented from damaged by using an automatic document feeder without noticing the document left by a former operator. |
