Automatic document feeder

Reverse automatic document feeder

A scanner with a duplexing automatic document feeder

A Konica Minolta photocopier with an automatic document feeder in use

In multifunction or all-in-one printers, fax machines, photocopiers and scanners, an automatic document feeder or ADF is a feature which takes several pages and feeds the paper one page at a time into a scanner or copier, allowing the user to scan, and thereby copy, print, or fax, multiple-page documents without having to manually replace each page.

Most copiers allow scanning on the flatbed or platen (the "glass") or through a document feeder. The vast majority of fax machines have an ADF, allowing the unattended sending of multi-page faxes. ADF is so ubiquitous in fax machines that some fax machine owners use the machine as a scanner, faxing multi-page documents to themselves. Document feeders are described by speed, in pages per minute or ppm, and capacity, usually in a range from 10 sheets to 200.

There are two types of document feeders capable of two-sided (duplex) scanning: a reversing automatic document feeder (RADF) and a duplexing automatic document feeder (DADF). An RADF scans one side of a page, then flips it to scan the other side, while a DADF scans both sides in a single pass. The advantage of the DADF is its faster speed for two-sided originals. Both RADFs and DADFs are rated in images per minute (IPM), which refers to the number of sides they can scan per minute, though this may depend on the resolution being used rather than the maximum supported resolution.

See also

• Duplex printing