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How does a Photocopier use Static Electricity?
Transcript of How does a Photocopier use Static Electricity?
Photocopiers are extremely useful items in our lives. Although with advancing technology we have other methods to duplicate documents, photocopiers can come in handy in various situations and having the physical copy can be very beneficial. The photocopying process can seem complicated but it uses a very simple physical principle:
. Here are the basic steps a photocopier uses to do its job and how this process uses static electricity.
For the copier to begin working, the drums photo conductive material must first be coated with positively charged ions by the corona wire. When you hit start, the lamp moves across the paper you wish to copy and shines light onto it. This makes the drum start to rotate. The light reflects off the blank areas of the paper and mirrors direct it to the surface of the drum. The dark areas of the paper simply absorb the light. In the areas where the light did hit the drum, the positively charged photo conductive material is neutralized. Positively charged ions only remain in the areas where the light did not strike. (These areas are for the text or pictures.)
The drum rotates at the same speed as the light beam moves across the original document so that it can build the image strip by strip. Once a strip of light focuses onto a corresponding strip on the drum, the drum rotates and reveals a new area of photo conductive material. While all of this is happening, the previously exposed area on the drum rotates past rollers covered with toner. Tiny negatively charged toner particles press themselves against the drums remaining positively charged areas.
Since the paper can be quite large, the drum needs to go through this process multiple times to make the full copy.
Materials in Photocopier
Once the original document has been recreated, the paper goes through the fuser. This is to ensure that the toner and image stay on the paper permanently. To do this, the sheet is sent between two Teflon coated rollers that gently press down on the page. Since the toner is heat sensitive, the quartz tube lamps inside the rollers generate heat and melt it. The rollers are covered in Teflon to prevent the toner from melting onto the tubes instead of the paper. When you reach to collect your copy, the photocopier has already prepared itself for the next task by cleaning the drum and coating it with another layer of positively charged ions.
By: Emma Joyal
The other corona wire then passes over the sheet that will be used for the copy and makes it positively charged. The area on the drum coated with toner rotates and contacts the new sheet of paper. The positive charge on the sheet is so strong that the negatively charged toner is pulled away from the drum onto the paper.
The drum is a metal roller that is layered with photo conductive material made from a semi-conductor such as silicon, germanium, or selenium. In the dark these materials act as insulators, however, when hit by light they become conductors and allow currents to pass through them. The drum is positively charged and has a big impact on the photocopying process.
Toner is a negatively charged plastic based fine powder that helps create the image on the copy.
The Corona Wires
For the drum and the copying paper to have a positive charge, the copier needs corona wires. The wires are exposed to high energy, which they transfer to the drum and paper in the form of static electricity.
The fuser is the last step of the photocopying process and is what makes the image permanent on the page. The fuser unit is made up of two Teflon covered rollers which have quartz tube lamps inside of them that generate heat.
Light and Lenses
A strong light is needed inside the photocopier to reflect parts of the image onto the drum to make the copy. There is also a mirror attached to the lamp assembly that guides the reflected light through a lens and onto the drum below it. You can change the length between the drum and the lens to reduce or magnify the size of the copy.
GCSE PHYSICS - How does a Photocopier Work? - How is Electrostatic Charge used in a Photocopier? - GCSE SCIENCE. (n.d.). Retrieved November 1, 2015, from http://www.gcsescience.com/pse10-electrostatic-photocopier.htm
Meeker-O'Connell, Ann (2001, January 31). How Photocopiers Work. Retrieved November 1, 2015, from http://home.howstuffworks.com/photocopier5.htm
Uses of Static Electricity - Pass My Exams: Easy exam revision notes for GSCE Physics. (n.d.). Retrieved November 1, 2015, from http://www.passmyexams.co.uk/GCSE/physics/uses-of-static-electricity.html
Woodford, Chris (2007). Photocopiers. Retrieved November 1, 2015, from http://www.explainthatstuff.com/photocopier.html
One of the wires is parallel to the drum and the other is situated so that it can charge the blank paper as it shoots by on its way to the drum.