The amazing Photocopier part 1

It's amazing how you go in a photocopying room, place the piece of paper into the machine, press a few buttons then you get a load of the same pieces of paper you wanted! Yes I would agree, the photocopier is a pretty good invention. But, you wonder, how does it work?

Well lets start from the beginning. To understand how a photocopier works, you need to learn all the pieces from simple to complex. We start with the special drum inside the copier. Have you ever tried rubbing a balloon on your sweatshirt to create static electricity? Well, that's what the drum inside the copier does. It charges up with static electricity. Inside the photocopier, there's also the toner. It's a very fine black powder which gets attracted by the static-charged drum.

There are three things about the drum and the toner that let a copier perform its magic:

• The drum can be selectively charged, so that only parts of it attract toner. In a copier, you make an 'image' -- in static electricity -- on the surface of the drum. Where the original sheet of paper is black, you create static electricity on the drum. Where it is white you do not. What you want is for the white areas of the original sheet of paper to NOT attract toner. The way this selectivity is accomplished in a copier is with light -- this is why it's called a photocopier! (I will get to the scanning soon.)


• Right now, the toner is on the piece of paper. Somehow the toner on the drum needs to get on the piece of paper. So then, something charges up the piece of paper with static electricity. It then pulls the toner off the drum and onto the piece of paper. The toner then turns into a common modern (?) word, ink.


• The toner is heat sensitive, so the loose toner particles are attached (fused) to the paper with heat as soon as they come off the drum.

The drum, or belt, is made out of photo conductive material. Here are the actual steps involved in making a photocopy:

1. The surface of the drum is charged.
2. An acute beam of light or laser scans across the piece of paper that you have placed on the platen's surface. The laser light is reflected from the paper and strikes the drum below.
3. Wherever a photon of the light or laser strikes, electrons are emitted from the photoconductive atom in the drum and neutralize the positive charges above. Dark areas on the original (such as pictures or text) do not reflect light onto the drum, leaving regions of positive charges on the drum's surface.
4. A positively charged sheet of paper then passes over the surface of the drum, attracting the beads of toner away from it.
5. The paper is then heated and pressed to fuse the image formed by the toner to the paper's surface.

When the copier illuminates the sheet of paper on the glass surface of a copier, a pattern of the image is projected onto the positively charged photoreceptive drum below. Light reflected from blank areas on the page hits the drum and causes the charged particles coating the drum's surface to be neutralized. This leaves positive charges only where there are dark areas on the paper that did not reflect light. These positive charges attract negatively charged toner. The toner is then transferred and fused to a positively charged sheet of paper.

I got this idea from http://www.howstuffworks.com/.