| 摘要 |
PURPOSE:To accurately detect whether or not there is a document by updating a decision level automatically according to a detected value in the presence of the document and a detected value in the absence of the document and using a detected value, based upon light reflected by an end part of the document, for decision level calculation. CONSTITUTION:A microcomputer 24 compares detected values as the outputs of document detection sensors 7, 8, and 12 with the specific decision level to detect whether or not there is the document. In automatic decision level setting mode, the decision level is set according to the detected value in the presence of the document and the detected value in the absence of the document and the detected value based upon the light reflected by the end part of the document is used for decision level calculation. Here, a character is seldom written at the end part of the document and the end part is frequently blank, so the detected values where the capabilities of the document detecting means 7, 8, and 12 are reflected are obtained and the decision level can be updated according to the capability decreases of the document detection sensors 7, 8, and 12. Consequently, whether or not there is the document can accurately be detected. |
