Who invented the photocopier and when

A. Chester F. Carlson began experimenting with producing a prototype photocopier in New York in the late 1930s.

Q. How do photocopiers work

A. Photocopier works on a basic physical principle: opposite charges attract.

Q. What are the basic components of the photocopier

A. The drum, or belt, the toner and the corona wire.

Q. What is special about the drum or belt in a photocopier

A. The drum, or belt is selectively charged with static electricity and so only attracts negatively charged toner where the original sheet of paper is black. Light is used to create the selectivity, hence the name 'photocopier', after photons, which are light particles.

Q. How do the corona wires work in a photocopier

A. The corona wire generates the necessary positive charges on the drum and the copy paper.

These wires are subjected to a high voltage, which they subsequently transfer to the drum and paper in the form of static electricity.

Q. What is toner, is it ink

A. No, although it's sometimes referred to as 'dry ink', toner is actually a fine, negatively charged, plastic-based powder.

Q. So, what happens when a piece of paper is photocopied

A. When you close the lid and press start, a beam moves over the image, but only light from the white areas is reflected back onto the positively charged photoreceptive drum, neutralising the charged particles in its path. As a result, only positive charges remain on the drum where dark areas exist on the original paper.

These positive charges attract the negatively charged toner. Because paper is an insulator, rather than a conductor, it holds the electrical charges in place and rollers apply heat and pressure to fuse the toner image to the paper, reproducing an excellent copy of the original.

Is there another piece of office technology that baffles you Why not ask how it works here.

By Lisa Cardy