what is output device

Output devices give output from the computer to the external world. Different output devices are:

Monitor

Printer

Flat-panel Display

Plotter

Microfilm devices etc.

Flat-Panel Displays

For laptop computers more compact, low power, durable monitors are used. A number of flat-panel display technologies are available for this. Of them the plasma and liquid crystal displays are most common.

Plasma Displays

A plasma display consists of ionized neon or argon gas (plasma) sealed between two glass-plates. One plate encases a set of fine horizontal wires and the other a set of vertical wires. Pixels are formed by the intersections of the horizontal and vertical wires. Sending a current through its horizontal and vertical wires can turn on a single pixel. This causes the gas between the wires to produce an amber glow. The images produced by plasma displays are generally very clear, and not subject to the flicker. Plasma displays are generally more expensive than the CRT displays.

Liquid Crystal Displays

Liquid crystal displays (LCD’s) have been used for several years in calculators and digital watches. A thin layer of a liquid crystal substance is suspended between two thin sheets of polarized glass and separated by a wire grid into tiny squares. As current is applied to the wires the liquid crystal substance within the square changes from clear to opaque or black. The thousands of clear and black squares produce patters of characters.

The disadvantage of LCD displays is lack of brightness and resolution as compared to CRT and plasma displays. The quality of the LCD display depends on the surrounding light and the viewing angle. It is sharpest and clearest when viewed in brightness from the front.

Plotter

An inexpensive portable plotter capable of generating multicolor plots from data is stored on magnetic tape or disk. Plotters with multicolor capabilities generally use a writing mechanism containing several pens, each capable of producing a different color. Some devices for automated drafting are equipped with plotting surfaces larger than 10 square feet and cost as much as a minicomputer system.

Whether an application is a general one (such as designing, mapping, or plotting schematics) or more specialized (such as three-dimensional data presentation, structural analysis, contouring, or business charts), there are plotters to do the tricks.

Microfilm Device

Computer output microfilm (COM) devices convert computer output to a human-readable form, stored on rolls of microfilm or as microfilm frames stored on cards called microfilm. At speeds of 10,000 to over 30,000 lines per minute, COM is one of the fastest computer output-techniques. It is more than ten times faster than the fastest impact printer is. A single roll of microfilm can store approximately 2000 frames and costs less than half the cost to print the same amount of data on paper.

Because of the high cost of COM equipment, it is generally only practical for larger businesses or industries generating approximately several thousand documents per day. COM devices are commonly used in libraries, mail-order concerns, defense installations, government agencies, and similar, large operations.

what is output device