Laser Printers

1
Laser Printers

• By Dan Hill

2
Goals

• What components make up a laser printer?
• What role does each component play in the
  functionality of laser printers?
• What are the advantages of using a laser printer
  vs. ribbon printers?

3
Components

• The Controller
• The Laser
• Laser
• Moveable mirror
• Lens
• Photo Sensitive Drum
• Toner Hopper and Roller
• Discharge Lamp
• Corona Wires and Fuser

4
Basic Process

• Printer accepts input from computer
• Formatter board interprets the input
• Instructions sent to laser where laser shoots
  beam onto photo drum
• Drum rotates past toner, where ink is attracted
  to the drum
• Paper passes through fuser and exits printer

5
How does it work?

• A laser printer needs to have all the info about
  a page in its memory before it can start printing
• Printers onboard computer talks to host
  computer
• Raster image processor takes page data and breaks
  it down into an array of tiny dots.

6
How does it work?

• Laser system combined of 3 items
• The laser
• Moveable mirror
• Lens or series of lenses
• Laser receives page data from PC, one horizontal
  line at a time. The laser emits a pulse of light
  for every dot to be printed.

7
How does it work?

• Drum rotates while laser places charges onto the
  drum. Laser is turned off and on as it is
  scanned across one line to produce charges.
• Drum shifts downward and laser begins to scan
  next line
• Drum moves at same speed as paper to identically
  map image onto paper.

8
How does it work?

• Toner electrically charged () powder
• Attracted to (-) charged portions of drum caused
  by laser.

9
The leftovers

• Corona wires charged wires
• Discharge Lamps Erase the charge on the photo
  sensitive drum as it rotates before laser hits
  drum with another charge
• Fuser Paper is squeezed between 2 rollers, one
  of which is hot. Heat forces toner to bond to
  paper.

10
Advantages

• Speed, Precision, economy
• Laser can write at great speeds
• Dont have to worry about smearing ink
• Toner is cheap
• Laser has unvarying diameter, and can draw very
  precisely