FUJITSU fi-4120C - Manual (Page 81)

54 4.4 Detecting Double-feeds
Check length : The scanner uses a sensor to monitor the
length of documents that are fed. It
detects a double-feed by changes in the
document length when two or more
document sheets are fed overlapping.
Check thickness and length
: The scanner monitors both document
thickness and length to detect double-
feed.
Furthermore, see "8.5 Double-feed Detection Conditions" for
detailed information about the document for double-feed
detection.
4.
Click the [OK] button.
The display returns to the [TWAIN Driver] dialog box.
Continue scanning from this dialog box.