LED Vs. Laser Printersby Steve Lander
Printers using laser and light-emitting diode technology are very similar. Both are "page" printers that generate a full page of output at a time, use light to inscribe the page image on a photosensitive drum that then picks up solid toner particles, use electrical charges to transfer the toner from the drum to the paper, and use an extremely hot fuser to melt the toner onto the paper. The only difference between the two technologies comes from their light source.
LED printheads have a row of very small LEDs that cover the entire page. For example, a 600 dot per inch resolution letter-sized printer has 4,800 LEDs across its eight-inch-wide printing area. The LEDs blink each line of the document in rapid succession, charging the drum so that it picks up the toner to transfer it to the paper.
Instead of a fixed array of LEDs, laser printers use a single laser beam. The laser beam bounces off of a rotating mirror which aims it at the drum, going back and forth to inscribe the page image, one pixel at a time. Some printers can vary the size of the laser beam, giving them more control over their resolution.
LED printheads are much simpler than laser printheads. They have no moving parts and have a simple, straight paper path. Their simplicity makes them less expensive to manufacture, which is why many lower cost printers use them. LED printers are also quieter than laser printers, again due to their lack of moving parts in the printhead, and can be much smaller.
Laser printers benefit from having a single light source that can move. This eliminates two of the key problems of LED printers -- having the individual LEDs fall out of alignment and having slight differences in light output between LEDs in a printhead. The single beam in a laser printer means that every dot gets illuminated in the same way. Because laser printers do not need to have a row of LEDs, they can also make smaller dots and have higher effective resolutions.
- photo_camera red led image by Kir from Fotolia.com