How Does A Photocopier Work?

Question

How Does A Photocopier Work?

2 Answers

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Answer 1

All photocopiers have a drum in them. The drum of a photocopier can be charged with a type of static electricity (like in the case of a balloon). When the drum is charged with static electricity, it attracts the toner. The toner is a powder which has a very fine texture and is black in colour.

The drum is selectively charged in order to effectively attract parts of the toner. The toner first gets onto the drum and then onto the sheet of paper. A copier makes an image in static electricity on the surface of the drum.

The toner is sensitive to heat. The loose particles of the toner get fused to the sheet of paper with heat when they come off the drum. The drum (or belt) is made of a photoconductive material.

Answer 2

It is a very simple process. The photocopier process is called xerography, from the Greek word 'xeros' and 'graphos' meaning 'dry writing'. The heart of machine is a drum which is an aluminium cylinder coated with a layer of selenium. Aluminium is an excellent conductor .On the other hand, selenium is an insulator in the dark and become a conductor when exposed to light, it is a photoconductor. If a positive charge is sprinkled over the selenium it will remain there as long as it remain in dark .If the drum is exposed to light, the electrons from alunium pass through the conducting selenium and become neutral.

If the drum is exposed to an image of the document produce corresponding area on the drum .The dark area retain the positive charge, but light area become neutral. Positive charge image of the document remain on the surface. Then a special dry, black powder called' toner' is given a negative charge and spread over the drum, where it sticks to the positive charged areas. The toner from the drum is transferred on to a sheet on which the document is to be copied. Heated pressure rollers then melt the toner into the paper to produce the permanent impression of the document.