| 摘要 |
PROBLEM TO BE SOLVED: To provide a document reader having reduced manufacturing cost for accurately detecting the front and rear ends of documents and the double feed of the documents. SOLUTION: In accordance with how many ultrasonic waves is received by a receiver after transmitted by a transmitter, the front and rear ends of the documents are detected and the double feed of the documents is detected. A mechanism for detecting the front and rear ends of the documents is used in common with a mechanism for detecting the double feed of the documents to reduce the manufacturing cost. After the ultrasonic waves are continuously transmitted by the transmitter to detect the front end of the document, the ultrasonic waves are changed to be cyclically transmitted in predetermined transmitting cycles T1 to detect the double feed of the document. After the double feed is detected, the ultrasonic waves are changed to be continuously transmitted by the transmitter again to detect the rear end of the document. Thus, the front end rear ends of the documents and the double feed of the documents are accurately detected. COPYRIGHT: (C)2008,JPO&INPIT
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