FUJITSU fi-4120C - Manual (Page 157)

130 8.5 Double-feed Detection Conditions
■ ■ ■ ■ Detection by Document Length
Sheets of the same length shall be set in the ADF at a time.
• Document length deviation: 1% or less
• Printed area: 12% or less
• No black printed areas are allowed at the center area
(26 x 10mm) at the leading edge of the document.
• Punched holes are not allowed within 35mm of the vertical
center line of the document.
• The deviation in the amount of the light transmitted through
background areas must not be less than 10%.