How do photocopiers copy?

Full Description

How a photocopier works

First, the surface of a cylindrical drum is given an electro-static charge by a high-voltage wire called a corona wire. The drum is coated with a photoconductive semiconductor material, such as selenium or germanium.

Then the image of the scanned original document is beamed in a narrow band onto the surface of the drum. Only the white areas of the original reflect light. The light then hits the drum, which is specially conditioned to make it photoconductive. This means that when light hits it, the positive charges are conducted away to a ground.

As a result, the white areas of the picture are now neutral, and the black areas are positive, yielding a latent electrical image on the surface of the drum.

The toner is negatively charged. When it is applied to the drum to develop the image, it sticks to the areas that are positively charged, just as paper sticks to a toy balloon with a static charge.

The toner image is then transferred from the drum onto a positively charged piece of paper.

The toner is a dry ink substance. If paper exited the photocopier covered in dry toner it would merely brush off. Toner usually contains a styrene or polyester resin, and with the application of heat and pressure it melts and binds (or fuses) to the paper.

For more details see

http://en.wikipedia.org/wiki/Photocopier

there was a cylinder.its serface will chrged with static electricity then the original copy expose to light and reflected to the cylinder

the dark area will keep the charge and the other will lose it .

then the ink powder will be suplied to the cylinder and only the area still have electrical chrge will catch the ink .then it presed with heat to a new paper.and you get a copy

Using a strong beam of light. The light is strong enough to pass through the paper but not the written part, hence enabling it to copy.

They scan da thing u want 2 copy an scan the same light on a different page!

when you close the lid and press the button, a vertically challenged person (have to be pc these days) shines a torch on the original to help to assist his/her eyesight.

The vertically challenged person is a highly skilled quick draw artist, bish bash bosh quick flick of the pen and pops it out the side....please think of the repetative strain injury that you can cause if you hit 99 copies.

Use your copier wisely and save a dwarf today..(sorry, vertically challenged person)