Translations:AY Honors/Computers/Answer Key/57/en

Laser Printer

A laser printer is a common type of computer printer that produces high quality printing, and is able to produce both text and graphics.

An electric charge is first projected onto a revolving drum. The drum has a surface of a special plastic or garnet. Electronics drive a system that writes light onto the drum with a laser. The light causes the electrostatic charge to leak from the exposed parts of the drum. The surface of the drum passes through a bath of very fine particles of dry plastic powder, or toner. The charged parts of the drum electrostatically attract the particles of powder. The drum then deposits the powder on a piece of paper. The paper passes through a fuser, which, with heat and pressure, bonds the plastic powder to the paper.

Laser printers are the workhorse printer of the business world. They are capable of producing very high quality prints very cheaply. Although most laser printers only work in black and white, some models can also produce color prints. Because of their speed and economy, laser printers have largely replaced all other types of printers except ink jet and thermal printers.

Ink Jet Printer

Most current inkjets work by having a print cartridge with a series of tiny electrically-heated chambers. To produce an image, the printer runs a pulse of current through the heating elements. A steam explosion in the chamber forms a bubble, which propels a droplet of ink onto the paper (hence Canon's tradename for its inkjets, Bubblejet). When the bubble condenses, surplus ink is sucked back up from the printing surface. The ink's surface tension pumps another charge of ink into the chamber through a narrow channel attached to an ink reservoir.

Compared to earlier consumer-oriented printers, ink jets have a number of advantages. They are quieter in operation than impact dot matrix or daisywheel printers. They can print finer, smoother details through higher printhead resolution, and many ink jets with photorealistic-quality color printing are widely available.

The disadvantages of inkjets include flimsy print heads (prone to clogging) and expensive ink cartridges (sometimes costing US$30 – $40 or more). This typically leads value-minded consumers to consider laser printers for medium-to-high volume printer applications.

A common business model for inkjet printers involves selling the actual printer at or even below production cost, while dramatically marking up the price of the (proprietary) ink cartridges.