The facsimile machine is a device for transmitting documents or photographs over a long distance between two remote sites or offices.
It was originally invented as a way of sending news items and photographs. It is based on an invention by Alexander Bain, a major pioneer in telegraphy, patented in Britain in 1843.
The document is inserted slowly into the machine and an optical scanning technique is used by a fluorescent light passing over the paper from side to side. The beam is reflected from the picture and falls onto a photoelectric cell which is a sensing device. As the light and dark areas of the image are shown, the brightness of the beam changes and this is picked up by the photoelectric cell, the changing current is then transmitted along the telephone wire via a modulator/demodulator or modem.
At the other end of the phone line the receiving fax machine has a roll of heat sensitive thermal paper (paper coated with iron compounds), as the incoming current is demodulated it controls a laser and the beam is reflected onto the paper. The light areas reflect the heat and it is dispersed but the dark areas cause a rise in temperature which turns the coating on the paper black, bringing out the image being transmitted.
The fax machine has seen a massive rise in popularity with businesses around the world during the 1980's and are used on many occasions to replace a telephone call or postal letter with savings on both time and money. Facsimile machine have also made business communications across continental time zones more convenient due to the fact that they can be sent and received unattended at any time day or night.
