Sunday, February 10, 2008

Computer Printer

A computer printer, or more generally a printer, produces a hard copy (permanent human-readable text and/or graphics) of documents stored in electronic form, usually on physical print media such as paper or transparencies. Many printers are mainly used as local computer peripherals, and are attached by a printer cable to a computer which serves as a document source. Some printers, commonly known as network printers, have built-in network interfaces (typically wireless or Ethernet), and can provide as a hardcopy device for any user on the network. Individual printers are often designed to support both local and network linked users at the same time.

In addition, many modern printers can straight interface to electronic media such as memory sticks or memory cards, or to image capture devices such as digital cameras, scanners; some printers are combined with a scanners and/or fax machines in a single unit. Printers that contain non-printing features are sometimes called Multi-Function Printers (MFP) or Multi-Function Devices (MFD).

A printer which is shared with a scanner can function as a photocopier if so designed. Most MFPs include printing, scanning, and copying among their features.

Printers are planned for low-volume, short-turnaround print jobs; requiring virtually no setup time to achieve a hard copy of a given document. However, printers are usually slow devices (30 pages per minute is considered fast; and many consumer printers are far slower than that), and the cost-per-page is relatively high.

In contrast, the printing press (which serves much the same function), is planned and optimized for high-volume print jobs such as newspaper print runs--printing presses are capable of hundreds of pages per minute or more, and have an incremental cost-per-page which is a fraction of that of printers.

The printing press remains the machine of option for high-volume, professional publishing. However, as printers have improved in excellence and performance, many jobs which used to be done by professional print shops are now done by users on local printers; see desktop publishing.

The world's first computer printer was a 19th century mechanically driven tools invented by Charles Babbage for his Difference Engine.

In 2007, a study exposed that toner-based printers produced pollution as harmful as that from cigarettes.

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