Probably you use a laser printer at your home or at your work.  Laser printer is a very advantageous equipment that allows you to print thousands of pages speedily and economically.  However, you may have wondered how your laser printer works so efficiently.  One of the most important functional parts is the toner drum in your laser printer

Of course, as you may have surmised from its name, a laser printer works by using a laser beam to etch the image of the document into the paper by using static electricity and by using a photoreceptor surface.  In essence, the toner drum is the most functional part of the printer, as it is responsible for pressing the image on to the paper.

The toner drum is positively charged and thus a positive static electrical charge is induced on the surface of the toner drum. Then the ink inside the toner is also positively charged by the printer mechanism.  As you know from Physics 101, two same charges will repel each other and two opposite charges will be attracted to each other.

In the next stage, a laser beam is beamed onto the surface.  At this time, the paper is negatively charged and the laser etches the image of the document (text and graphics) on to the toner drum.  Once the drum starts rolling, the black ink from the toner will be injected onto its surface.  As the positively charged black ink rolls on the drum (which has the document etched onto its surface by the laser); then the positive ink clings to negatively charged parts of the paper.  Hence, this static electricity works as a bonding agent or as super glue and thus the ink is pasted or bonded onto the paper.  As a result, you can get a perfect printout in a speedy and in an efficient way.