Document Scanner

Paper goes into a hopper, gets pulled past two sensor bars and lands in a tray on the other side as files. There is no printing half at all, which is why the feeder is engineered to a standard no all-in-one matches. This is a machine for clearing a backlog rather than for the occasional page.

Speeds run 25 to 60 pages a minute with hoppers holding 50 to 100 sheets, and single-pass duplex captures both sides in one pull. Ultrasonic double-feed detection listens for two sheets traveling together and halts the batch instead of silently losing a page. This is the failure that quietly ruins an archive. Feeders handle paper roughly 40 to 160 gsm, plus plastic cards on models that state it.

Ask for optical resolution and disregard interpolated figures, which are software inventions. Use 300 dots per inch for text you intend to search, since optical character recognition, the step that turns a picture of a page into words you can find, is tuned for exactly that. Choose 600 for archival paperwork and small print. Anything above 1200 belongs to film and enlargement work, and produces files of several hundred megabytes per color page.

Bound books, stapled originals, torn receipts and anything fragile stay off the feeder and belong on a flatbed, which usually means the All-in-One Printer you already own. Note that a contact image sensor sits close to the glass with almost no depth of field, so a book page lifted 2 mm blurs, while a charge coupled device scanner using a lens and mirrors holds focus several millimeters up.

Feed rollers are consumables, usually rated near 100,000 sheets and sold as a replacement kit. Wipe the narrow scanning strip beside them regularly, because one speck of correction fluid or adhesive there prints a black line down every page in the batch.