Following Bain's achievements, a group of inventors put the fax machine through many revisions before reaching its modern form.
Giovanni Caselli created the pantelegraph, which became the first commercial fax link between Paris and Lyon, France, around 1865. Building on Bain's ideas, Caselli's tall, cast-iron machine sent thousands of faxes each year.
Caselli's customers would write their message on a thin sheet of tin using a non-conductive ink. The operator would then place the tin on a curved metal plate and scan it with a needle and send it to another pendulum-operated machine in the other city. Because of the non-conductive ink used to write the message, the receiving end would get an inverse reproduction of the sheet.
In 1903, Arthur Korn achieved the first photoelectric scanning fax machine network that linked Berlin, London and Paris by 1910. His method represented a step beyond Bain's contact scanning.
Using the light-sensitive element selenium, Korn's machine could convert the various tones of a scanned image into different electric currents. His work remained the standard for decades and paved the way for the Associated Press to begin a photo wire service that could send news photographs around the world. Korn would also invent a commercial picture transmitter that used radio waves instead of wires to send pictures across the Atlantic Ocean.
The French engineer Edouard Belin invented a process that also could send photos [source: Tech News]. He would first chemically treat a photo, giving it an uneven contour based on its light and dark shades. A needle scanner picked up these contours and converted them into varying electric currents, which could be sent to another machine. His continuous work made the machines smaller, faster and more reliable. He also found ways to encrypt fax transmissions for security reasons.
In 1947, Alexander Muirhead demonstrated a fax machine incorporating a rotating drum scanner that became very successful.
Modern fax machines incorporate many improvements from previous versions, but the premise remains the same. The sender places an original on an electronic scanning bed where an electric "eye" looks at the paper and records the image there, whether it be a complicated "picture" or simple text. The scanner then digitizes the image, turning it into a series of 1s and 0s that it can transmit over phone lines or the Internet.
On the receiving end, a computer processor re-assembles the image from the digital information and prints it out, either to paper or onto a computer screen.
Instead of a rotating drum, modern fax machines use a photo sensor to "look" at the paper it's copying and sending. The sensor tells the difference between dark and light areas, which tell a computer processor how to reproduce the image at a distant location by encoding the information. The encoding makes it possible to send it along a phone line or over the Internet.
At the receiving fax machine, the machine reads the encoded information and reassembles the image.
Modern fax machines come in many variations regarding speed, capacity and resolution. Some work as stand-alone and others work in conjunction with computers. Still others are multi-function, working as copy machines and fax machines that send to other traditional fax machines or e-mail images to other computers.
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