How do Fax Machines Work. You can walk into nearly any office in the United States today, big or small, hi-tech or lo-tech, and you will find a fax machine. To see how do fax machines work refer to the links on the right of the page.

The Basic Idea
Fax machines have been around in one form or another for more than a century -- Alexander Bain patented the first fax design in 1843. If you look back at some of the early designs, you can get a very good idea of how they work today. Most of the early designs involved a rotating drum. To send a fax, you would attach the piece of paper to the drum, with the print facing outward. The rest of the machine worked something like this:

There was a small photo sensor with a lens and a light.
The photo sensor was attached to an arm and faced the sheet of paper.
The arm could move downward over the sheet of paper from one end to the other as the sheet rotated on the drum.

In other words, it worked something like a lathe.

The photo sensor was able to focus in and look at a very small spot on the piece of paper -- perhaps an area of 0.01 inches squared (0.25 millimeters squared). That little patch of paper would be either black or white. The drum would rotate so that the photo sensor could examine one line of the sheet of paper and then move down a line. It did this either step-wise or in a very long spiral.

To learn more about how do fax machines work and more information on fax machines, refer to How Stuff Work and Think Quest the two web links on te right of the page.