Laser vs. LED
What's the difference between laser and LED printers?
When you are shopping for a laser printer, make sure you take a good look at the spec -- you may actually be buying an LED printer.
Not that this is necessary a bad thing. Laser and LED (Light Emitting Diode) printers have existed side-by-side for some years now, and in fact, most users aren't able to distinguish between the print quality of the two. For this reason (and to keep marketing the printers simple), most stores and sales Web sites will class LED printers as laser printers. There are, however, some differences between the two.
How They Work
Here's basically what happens when you print using a laser printer: The printer has a revolving cylinder (called a drum) that is given a positive electrical charge. When you send an image of a document or a picture to the printer from your computer, the printer uses a low level laser beam to "draw" the image on the drum using a negative electrical charge. This is called an electrostatic image. (In some printers, this works with the charges reversed -- that is, a positive electrostatic image on a negative background.)
As the drum continues to revolve, it passes the toner cartridge. The toner consists of fine black powder, which clings to the electrostatic image created by the laser on the drum. It then rolls over the paper, which has been given an even stronger electrostatic charge, and so the toner transfers to the paper.
The paper, which is now on its way out of the printer, first passes a fuser, heated rollers which melt the powdered toner onto the paper.
LED printers work on the same principles. However, instead of a laser, an LED printer uses a group of LEDs built over the width of the drum, which are selectively beamed onto the drum in the form of tiny dots, or pixels.