Laser Printer Working :-
A Laser Printer is a bit mysterious , how can a laser beam , a highly focused beam of light write letters and draw pictures on paper.
Many people use laser printers in their day-to-day lives , but most probably never think about the technology that turns those bits of digital data into a legible images and text.
The Primary principle at work in a laser printer is static electricity , the same energy that makes clothes in the dryer stick together,
Static electricity is simply an electrical charge that build up on an insulated object , such as a balloon or your body.
Since oppositely charged atoms are attracted to each other , objects with opposite static electricity fields cling together.
A Laser Printer uses this phenomenon as a sort of temporary glue.The core component of this system is photoreceptor , typically a revolving drum or cylinder.This drum assembly is made out of highly photo conductive material that is discharged by light photons.
Initially, the drum is given a total positive charge by the charge corona wire - a wire with an electrcal current running through it.
As the drum revolves , the printer shines a tiny laser beam across the surface to discharge certain points.
In this way the laser draws the letters and images to be printed as a pattern of electrical charges - an electrical image.
After the pattern is set , the printer coats the drum with positively charged toner - a fine black powder.
Since it has a positive charge , the toner clings to the negative discharged areas of the drum , but not to the positively charged background.
This is something like writing on a soda can with glue and then rolling it over some flour.
The flour only sticks to the glue coated part of the can , so you end up with a message written in powder.
With the powder pattern affixed , the drum rolls over a sheet of paper which is moving along a belt below.
Before the paper rolls under the drum , it is given a negative charge by the transfer corona wire.
This charge is stronger than the negative charge of the electrostatic image , so the paper can pull this toner powder away.
Since it is moving at the same speed as the drum , the paper picks up the image pattern exactly.
To keep the paper from clinging to the drum , it is discharged by the detac corona wire immediately , after picking up the toner.