Making the Mark

• A Laser Printer Drum - Image from Flickr
  
  The beam of a printer's laser strikes the photoreceptive drum, etching a reverse image of the document or image to be printed. The light causes the area on the drum it strikes to take on a negative charge.
  
  

Attracting toner

• Toner - Image from Wikicommons
  
  the drum continues to roll and as it approaches the toner hopper, the positively-charged toner particles stick to the image drawn by the laser and stays there until it contacts the paper.
  
  

Releasing the toner

• The toner is drawn from the drum because the paper, having passed under a "corona wire" has a stronger negative charge. The paper is prevented from sticking to the drum because soon after the paper contacts the drum, it passes over another corona wire which gives it a positive charge.
  
  

Clearing the image

• The drum rotates under a "discharge lamp" which is a very bright light. This removes the image drawn on the drum by the laser by giving that area of the drum a total negative charge.
  
  

Set up

• the drum then rotates under a corona wire of its own where it receives a total positive charge and is ready to be drawn upon by the laser once again.