3. WHAT IS PHOTOCOPIER
•Definition
• The copying machine is called photocopier. This process is also known as
‘xerography’.
• It is the combination of two Greek words which means ‘Dry Writing’
1. Xeros means Dry
2. Graphos means Writing
• It is invented by Chester Carlson
4.
5.
6. Principal
• The working principal of photocopier machine is that “ the opposite
charges attract each other.”
• The other phenomena is photoconduction which means a insulator
material become conductor when light falls on it
7. CONSTRUCTION
• It consist of following major parts
• Drum
• it is made up of aluminum and coated with selenium. The aluminium is a good conductor
of charges and selenium is a photoconductor.
• Photoconductor is a material which become conductor on application of light
• Lamp
• It is a light source which provide necessary light energy
• Lens
• Focus the image on drum . Also reduce or magnify the size of image
• Toner
• It is a special kind of dry ink which is made up of carban and polymers
• Roller
• It provide heat, mealt toner and fix it on paper
8. WORKING
• Aluminum is good conductor it can provide free electrons
• Selenium is photoconductor (become only conductor when light
applied) consist of fine corona wires which are already positively
charged
• Paper to be copied has dark area (writing) and white area (spaces)
• It is placed on scanning mirror
• Light from lamp falls on paper, it could not pass through dark
area(words) and it pass only through empty spaces
• Hence it form shadow of words on focusing mirror
9. WORKING
• Focusing mirror direct these light patterns on selenium which contain positive
charge on its entire surface
• As it is photo conductor, the area on which light falls become conductor and
these area gets electrons from aluminum and become neutral.
• In this way the remaining positive charge create same pattern of words on
selenium drum
• Now Toner powder which is negatively charged is applied which attaches with
positively charged pattern of words
• When Blank paper is slide over to drum containing tonner powder the same
pattern is drawn on it
• When paper pass through Roller it melt tonner which permanently attached
paper
• In this way a photo copy of original page is created.
10.
11. USES
• Hand outs copies
• ID card copy
• Driving license copy
• Some machine can generate print also
