4-5Chapter 4 Other Functions3. Press the Start Key to start scanning.“Verifying…” is displayed.HintIf the specified count is exceeded while scanning, or if thescanned count does not reach the specified count whenscanning is finished, an error is displayed.The specified count is exceeded while scanningScanning finishes without reaching the specified count■ Double-Feed Detection FunctionThe scanner can detect double feeds. Two detectionmethods are used: comparison of document lengths, andultrasonic detection of spacing between documents, whichis set in the ISIS/TWAIN driver.IMPORTANT• When a double feed is detected, documents already fedthrough the feed inlet are transported to the eject outlet, andoperation stops.• The message that appears when a double feed is detecteddepends on the Rapid Recovery System setting specified inthe ISIS/TWAIN driver. See “When the Rapid RecoverySystem is Enabled” on p. 3-23 for details.• Double feed detection in the Count-Only mode is set in theUser Mode, and double feeds are detected ultrasonically.(See “Double-Feed Control Setting” on p. 4-11.)Detecting Double Feeds by Document LengthThis detection method is effective when scanningdocuments with pages of the same size. The length of thefirst page scanned serves as a standard for comparingsubsequent pages, and when a page is detected to beapproximately two inches (50 mm) longer or shorter thanthe standard, a double feed is detected and documenttransport is stopped.Ultrasonic Double-Feed DetectionThis detection method is effective when scanningdocuments with pages of different sizes. The spacebetween overlapping pages is detected ultrasonically, anddocument transport stops when a double feed is detected.Ultrasonic Double-FeedDetection Sensor
