Output Devices

The device which shows the results of processing and other information from the computer to the human understanding language form is called output device. Example Monitor, printer, plotter & speaker.

Monitor

The display screen that is used to display the text and graphics, allowing users to view the result of the processing is called monitor. It is the most common and popularly used output device for producing soft copy output. It displays the generated output on a television like screen. There are different types of monitors such as LCD, CRT etc.

CRT Monitor

CRT stands for cathode ray tube, describing the technology inside an analog monitor creates a picture out of many rows or lines of tiny colored dots. The more lines of dots per inch, the higher and clearer the resolution. Therefore 1024 X 768 resolutions will be sharper than 800 X 600 resolutions because the former uses more lines creating a denser, more detailed picture. Higher resolutions are important for displaying the suitable details of graphics.

 

Advantages

·         High Refresh rates

·         Color clarity and depth.

Disadvantages

·        Very Heavy and Large

·        Use Large Amounts of Energy

·        Generate excess Heat.

Liquid crystal Display (LCD) Monitor

LCD is a thin, flat electronic visual display that uses the light modulating properties of liquid crystals. Liquid crystals do not emit light directly.

They are used in wide ranges of applications, including computer monitors, television, aircraft cockpit displays etc, they are common in consumer devices such as video players, gaming devices, clocks, watches, calculators art telephones LCDs have displaced CRT in most applications. They are usually more compact, lightweight, portable, less expensive, more reliable, and easier on the eyes. They are available in a wider range of screen sizes than CRT and plasma displays.

Advantages

·         Smaller and Lighter

·         Less power Consumption

·         Causes Less Eye Fatigue

Disadvantages

·         Motion Blur on fast Moving Images

·         Some Models have reduced color clarity.

Light Emitting Diode (LED)

A LED is a semiconductor device that emits visible light when an electric current passes throng it. The chip has two reigns imparted by junction. The P region is dominated by positive charges, and N region is dominated by negative charges. The junction acts as barrier to flow of electrons between the P and N region. Only when sufficient Voltage is applied to the semiconductor chip, current flow, and electrons cross the junction into the P region. The light is not particularly bright, but in most LEDs it is monochromatic, occurring a single wave length. The output from a LED can ranges from red to blue violet.

Plasma Display

A plasma display panel (PDP) is a type of flat panel display common to large computer and TV displays 30 inches (76cm) or larger. They are called “plasma” displays because the technology utilizes small cells containing electrically charged ionized gases, or what are in essence chambers more commonly known as Fluorescent lamps.

Printer

An output device that produces text and graphics on paper is called printer. It is used to produce hard copy output. There are 2 types of printer.

·                     Impact printer

·                     Non-impact printer

Impact printers

An impact printer has mechanisms resembling those of a type writer. It forms characters or images by striking by a hammer or wheel against an inked ribbon, leaving an image on paper. Examples: Dot-matrix Printer, Daisy wheel printer etc

Non-Impact printer

Non- Impact printer is faster and quieter than impact printer because they have fewer moving parts. It forms characters and images without making direct physical contact between printing mechanism and paper. Example: - Laser printer, Ink -Jet printer

Difference between impact and Non- Impact printers

Impact printers		Non- impact printers
1. The head strikes ink coated ribbon to		1.	The thermal, chemical
print information.		or optical techniques are applied to
		Print
		information.
2.	They are noisy.	2.	They are less noisy.
3.	They are slow.	3.	They are fast.
4.	They are poor quality printers.	4.	They are high quality printers
5.	Example: Dot matrix printer ,Daisy	5.	Example : Laser printer, Ink-Jet
wheel printer etc		printer etc

 

Dot- Matrix printer

A more common type of microcomputer impact printer is the dot-matrix printer, which contains a print head of small pin that strikes an inked ribbon forming characters or images print heads are available with 9, 18 or 24 pins, with the 24 pin head offering the best print quality.

It is noisy and not good for continuous printing but it can print multi-pages i.e. it is possible to use carbon papers to get extra copies of the same document. It is flexible it does not have fixed characters font. As the font is not fixed, a dot matrix printer can print any shape of character.

Ink-Jet Printer

It is a non-impact character printer. Like dot-matrix printer, ink-jet printer also form images with little dots, but the dots are much smaller and more numerous. It sprays small, electrically charged droplets of ink from four nozzles through holes in a matrix at high speed onto paper. Most color printing is done on ink-jet because the nozzles can hold for different colors, CYMK (Cyan (blue-green), Yellow, Magenta (Purple-red), and Black, other colors are derived by the combination of these four colors. It is even quieter than laser printer and procedures and equally high-quality images.

Laser Printer

Laser printer is a non-impact printer, page printer. An entire page is processed at a time. It produces high quality print. Print resolution ranges from 300 to more than 2400 dpi (dot per inch). It is expensive than other printer.

Similar to a photocopying machine, a laser printer uses the principle of dot- matrix printers in creating dot-like images. However, these images are created on a drum, treated with a magnetically charged ink powder known as toner, and then transferred from drum to paper.

There are good reasons why laser printers are the most common type of non- impact printer. They produce sharp, crisp images of both text and graphics. They are quieter and faster than dot-matrix printer. They can print 4-20 pages per minute for individual micro-computers.

Plotters

A plotter is a specialized output device designed to produce high quality graphics in a variety of colors. Plotter is especially useful for creating maps and architectural drawings, although they may also produces less complicated charts and graphs.

It uses ink pen or ink –jet mechanism to draw graphics or drawings. Either single or multi colors pens can be employed. The pens are driven by motor. Drawing can be prepared on paper or plastic sheets.

Speakers

It produces and amplifies sound output. A good pair of speakers connected to sound card will give you loads of listening pleasure. The audio output of the computer system relayed through the speakers. More advanced speaker systems exit, allowing certain programs (such as music creation, software and games) to use surrounds sound capabilities to beneficial effect.