A document handler, such as used in a digital copier, includes an input
tray and an output tray, connected by a paper path. Along the paper path
are disposed two scan heads, one to record image data from each side of
the sheet. The two scan heads are separated from each other along the
paper path by a pitch length longer than a sheet to be scanned. The
arrangement allows an image on each side of the sheet to be scanned at an
exclusive time. For long sheets, a recirculation path, associated with
the paper path, is used to allow the sheet to re-enter the paper path: in
this way, one side of the sheet is scanned with one scan head, and then
the other side is scanned with the other scan head.