Computer printer
A printer is a piece of hardware for a computer. It allows a user to print items on paper, such as letters and pictures. Mostly a printer prints under the control of a computer. Many can also work as a copying machine or with a digital camera to print directly without using a computer.
Types of printers
Today, the following types of printers are in regular use:
- Inkjet printers, also sometimes called bubble jet printers use colored ink they put on a paper.
- Plotters are large format inkjet printers, or printers that use special pens.
- Laser printers transfer tiny particles of toner onto the paper. Most do not print colors.
- Dot-matrix printers are now almost extinct. They used a ribbon and made a lot of noise. There were models with 9 pins and models with 24 pins.
- Dye sublimation printers produce very high quality images. Three colors are used. Cyan, Magenta and Yellow. Each color is printed one at a time from cellophane sheets. The image is the sealed with an clear top layer. Some small photographic printers made by Kodak and Canon use this process.
- Daisy Wheel printers are a typewriter printer. Results look hand-typed with excellent looking text, no real graphics and very loud.
- Line printers contain a chain of characters or pins that print an entire line at one time. Line printers are very fast, but produce low-quality print.
- Thermal printer is an inexpensive printer that works by pushing heated pins against heat-sensitive paper. Thermal printers are widely used in calculators and fax machines. Many 20th century computer printers worked this way.
Producing output
Printers are programmed using a programming language. The printer interprets the program, and the outputs the result. There are two big classes of such languages: Page description languages, and Printer Control languages. A page description language describes what a page should look like. The program in a page description language is sent to the printer, which interprets them. Printer command languages are at a lower level than Page description languages, they contain information that is specific to the printer model.
Common programming languages for printers include:
Cost of printers
Whewn comparing the cost of a printer, people often talk about how expensive it is to print one page. This cost usually has three components:
- The cost of the printer, how expensive it was to buy the printer
- The cost of the consumable; the printer needs supplies (called toner, ink, or ribbon) to print
- The cost of the paper; some printers need special paper to print on
Printers that are more expensive to buy will usually be less expensive in the consumables (the ink, toner, or ribbon used by the printer). Therefore, laser printers are often more expensive to buy than inkjet printers, but are not as expensive to use over a long period of time. Inkjet printers on the other hand have a higher cost of consumables because the ink tanks they use are more expensive than the toner for a laser printer. Laser printers that can print in color are usually more expensive than those that only print in black and white. Other options, like being able to print on both sides of a sheet of paper, to automatically sort the output, or to staple the output will also make a printer more expensive..
