What Is a Printer?

printer

A printer is a computer peripheral device which accepts commands from users to print out texts, numbers or images onto flat media such as paper. Printers can be connected to the computer either directly by a dedicated data cable such as USB, or indirectly through a local area network using cables or wireless radio (like Bluetooth).

A laser printer uses a drum that has been coated with a toner powder, which is then transported across the surface of the drum in the outline of the desired image. A laser or LED is then shone on the drum, and the toner particles are attracted to those areas which do not have the original image printed on them, and are then fused to the paper through a heating process. A photocopier essentially does the same thing, but with ink rather than toner.

Inkjet printers use a cartridge that contains ink, which is then sprayed onto the paper to produce the image. Inkjet printers can be low or high cost, depending on the quality and number of copies required.

With the advent of the first HP LaserJet in 1984, and the inclusion of Postscript in the Apple LaserWriter the same year, laser printers were able to mix text and graphics, as well as to print in both black and white and color, producing output that was previously only possible from expensive commercial typesetting systems.

The printing process was still prone to minor timing errors, which caused what appeared as vertical misalignment of the resulting characters, and in chain or drum printers, horizontal misalignment with crowded printed characters appearing closer together or farther apart. These problems were reduced by the addition of a bar code symbol to each printed character, allowing the printed characters to be uniquely identified.