Output Technologies

An output device is an electromechanical, which accepts data from a computer and translates them into a form which is suitable for use by the outside world. Monitor, printer, plotter, speaker and scanner are some of the examples of output devices. These output devices convert the input data into the internal codes used by the computer and also converts internal codes into human readable form while supplying the output. They are connected to the computer system through I/O ports.

Output devices generate a computer output: 

• Soft-copy: output: it cannot be touched but is easily editable. Output displayed on a terminal screen is soft-copy output. 

• Hard-copy: A hard-copy can be touched but is not easily editable. Output generated by printer is hard-copy output. 

Some of the Output Devices are:

1.  Monitor:

Computer monitors are similar to television screen. Virtually everything in a monitor is electronically controlled. The absence of mechanical complexity greatly reduces the likelihood of failure. Video Display Terminal: Output and input devices attached together. The two basic types of monitors are Cathode Ray Tube (CRT) Flat panel. In order to connect a monitor to computer, you must have a graphics adapter card (also known as a video card). The graphics card is plugs into an expansion slot in motherboard inside the computer and the monitor plugs into the graphics adapter card.

2. Printer

Printer helps to print text or any other information on paper. The types of printers:

(a) Daisy wheel printer:

 Daisy wheel printer has a plastic or metal wheel on the shape of each character stands out. A hammer presses the wheel against a ribbon, which in turn makes an ink stain in the shape of the character on the paper. These printers are noisy and slow. Daisy wheel printers are impact printers since they print by hammering the wheel against ribbon. Dot-Matrix Printer:

 Dot matrix printer produces characters by striking pins against an ink ribbon. Print head is a part of these printers which consists of a matrix of tiny needles, typically seven rows with nine needles in each which hammers out characters in the form of patterns of tiny dots. They can print multi-page forms (that is, carbon copies). Dot matrix printers are impact printers. 

(b) Ink-jet Printer:

 Ink jet print characters by spraying small drops of ink at a sheet of paper. The ink is different from normal ink having a high iron content. There are magnetized plates in the ink?s path which direct the ink onto the paper in the desired shapes. Ink-jet printers are capable of producing high quality print approaching that produced by laser print. They can not produce multiple copies of a document in a single printing. Ink-jet is slower than laser printer and ink-jet printers require a special type of ink. Ink-jet printers are non-impact printers because they print by spraying ink on the page. Hence they are quite in operation. 

(c) Laser printer:

 Laser printer uses a beam to produce an image on a drum. Laser printers produce very high-quality print and are capable of printing an almost unlimited variety of fonts . 

(d) LCD and LED Printer:

 These printers are similar to a laser printer. Instead of using a laser to create an image on the drum as in the laser printer. These printers shines a light through a liquid crystal panel. Individual pixels in the panel let the light pass or block the light, thereby creating an image composed of dots on the drum. Liquid crystal shutter printers produce print quality equivalent to that of laser printers. 

(e) Line printers:

 Line printers are very fast printers which can print in the range of 300 to 2500 lines per minute. The disadvantage of line printers is that they can?t print graphics, the print quality is low, and they are very noisy. 

(f) Thermal printer:

 Thermal printer uses heat to transfer an impression onto paper. These printers produce images by pushing electrically heated pins against special heat sensitive paper. They are inexpensive and are used in many fax machines. They produce low quality print, and the paper tends to curl and fade.

3. Plotter

   Plotter is an output device for translating information from a computer into pictorial or graphical form on paper or a similar medium. A Device that draws pictures on paper based on commands from a computer. Plotters differ from printers in that they draw lines using a pen. As a result, they can produce continuous lines, whereas printers can only simulate lines by printing a closely spaced series of dots. Plotters are expensive than printers. They are used in engineering applications where precision is mandatory.

4. Sound cards and Speakers:

Sound card is an output device which is related with the production of sound in the computer system. Sound cards are necessary for nearly all CD-ROMs. Sound cards enable the computer to output sound through speakers connected to the board, to record sound input from a microphone connected to the computer, and manipulate sound stored on a disk. There are two basic methods which are used by Sound cards to translate digital data into analog sounds: FM synthesis: This method mimics different musical instruments according to builtin formulas. 

Wavetable synthesis: This method relies on recordings of actual instruments to produce sound. Wavetable synthesis produces more accurate sound, but is also more expensive. 

Working of Sound Card:

The sound card records audio by converting analog into digital data using on analog-to-digital converter chip. These digital signals are sent to a digital signal processor (DSP) chip that can be considered as the heart of the sound card. This chip frees the computer?s processor by taking over tasks relating to processing of the digital sound signals. This processed data is then stored in files on the hard disk or other media in the prescribed format, typically WAV or MIDI. Playing back these sound files involves sending the data in these files to the DSP chip, that in turn process it and sends it to a digital-to-analog converter chip. This chip converts the digital signals into an electrical current that is amplified by the speakers to produce sound. Sound card interfaces should include a line input, line output, microphone and speaker connectors.

5. 3D Audio

   3D audio is a technique in which more depth is given to traditional stereo sound.

6. Voice Output

It uses sophisticated synthesizer software to construct the sonic equivalent of textual words.

Related: Input Technologies
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