Fax machines

Like photocopiers, fax machines reproduce identical copies of documents. But they do it without the physical image. Data, detailing how the copied image should appear, are transmitted from one fax machine to another using telephone lines.

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Digital display: Shows the phone number of the machine receiving or sending a fax.

Handset: When not sending or receiving a fax, users can make telephone calls with the handset.

Feed slot: A document to be faxed enters the machine here.

Printed fax: This fax, which was sent to the machine by another, is an exact copy of the original document.

Paper cutter: As faxes are received by the machine, a blade slices an internal roll of paper into individual sheets. Plain paper sheet-fed faxes do not have a cutter.

Toner roller: The toner roll distributes a dark powder to the paper according to the electronic signals it receives from the scanner.

Scanner: As a document passes by, the scanner sends out beams of light, noting the light and dark areas. Electronic signals corresponding to the dark areas are sent to the toner roller, which applies the ink.

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Reading an image

The light and dark areas of a document are noted by a charge-coupled device within the machine and converted into variations in voltage. To speed transmission, those variations are digitized and encoded. The signal is then sent through a telephone line to the receiving machine, which decodes the signal.

Researched by CHRISTINE FREY/For The Times