What are Output Devices?

Output devices are those devices which is used to display output given by computer. These output may be in the form of Visual Display or any hard copy. The most common output devices are monitor, printer and Speaker. These output devices give instant feedback to the user’s input. This can include peripherals, which may be used for I/O purposes like network interface card(NICs), modem, IR ports, RFID systems and wireless networking devices.

Types of output devices are:

1}VDU or Monitor 2}Printer 3}Speaker 4}Speech Generating Devices 5}Plotter 6}Film Recorder

7}Braille Embosser 8}Headphones 9}Computer output Microfilms 10}Projector 11}Sound Card 12}Video Card

1} VDU or Monitor:

It is very important device for any of the computer which can use for instant display of data or information. VDU and monitor both are almost same. It is British term used for monitor. The term VDU is commonly used for CRT screen. Sometimes it is also called as VDT(Visual Display Terminal).Now the standard has been changed and named by Flat Panel Display. It is a device which is used to display text, image or both on the monitor. It is just like a T.V. Screen.

Types of Computer Monitor:

A)  CRT

B)   LCD

C)   LED

D)  Plasma Display

A)  CRT:

CRT is a first Computer Monitor which is also known as ‘Broun Tube’ because it is invented by German Physicist Ferdinand Broun in 1987. CRT is known as Cathode Ray Tube. A CRT is basically a vacuum tube containing a electronic gun at one end and a fluorescent screen at another end. While CRT monitors can still be found in some organizations, many offices have stopped using them largely because they are heavy, bulky, and costly to replace should they break.

The first computer monitor was part of the Xerox Alto computer system, which was released on March 1, 1973.

B)   LCD:

LCD is a type of flat panel display. It probably known as Liquid Cristal Display was invented by George Heilmeir in 1968. It consist of layer of colors or monochrome pixels arranged schematically between a couple of transparent electrodes and two polarizing filters.

LCD is of two types:

1} Active Matrix or TFT: It was first introduced in the year 1992 by IBM ThinkPad. In this technology each pixels is controlled by the 1 to 4 transistor. It is also known as AMLCD(Active Matrix Liquid Cristal Display).

2} Passive Matrix Technology: Passive displays are widely used with segmented digits and characters for small readouts in devices such as calculators, printers. Passive matrix is less costly because transistors are used to activate rows and columns, not each sub pixel, resulting in fewer manufacturing steps. It is slower than the TFT and chipper.

Newer passive-matrix technologies include CSTN (Color Super-Twisted Nematic), DSTN(Double Layer Super-Twist Nematic), and HPA (High-Performance Addressing displays). They offer higher contrast and brightness than older passive-matrix displays.

C)  LED:

It is also a flat panel display which is known as Light Emitting Diode. It was developed by James P. Mitchell in the year 1977. It uses array of diode as a pixels for display. It uses less power than their counter LCD and CRT. It is also environmental friendly technology. The advantages of LED monitors are that they produce images with higher contrast. They are more durable than CRT or LCD monitors, and features a very thin design. Modern electronic devices such as mobile phones, TVs, tablets, computer monitors, laptops screens, etc., use a LED display to display their output.

LED are two types:

1} Organic LED: This type of LED contains organic materials as the name indicates which are manufactured in sheets and provide a diffuse area of light. OLED technology, first successfully implemented in 1987 by Kodak researchers Ching W. Tang and Steven Van Slyke. This allows the OLED array to produce brighter light while using less energy than existing LCD/LED technologies. Active matrix OLEDs, like the AMOLEDs you might find in a smart phone. These are for high-definition applications that demand fast refresh rates, such as smartphone screens or HD televisions.

2} High Brightness LED:  The high brightness LEDs (HBLEDs) are the type of organic LEDs and these are widely used for lightening purpose. This type of LED is essentially the same as the basic inorganic LED, but has a much greater light output. For generating high brightness, these LEDs are required to be able a high current and high power dissipation therefore these LEDs are mounted on heat sink for removing the unwanted heat.

D)  Plasma Display:

This Display is also a flat panel display which uses plasma(An electrically charged ionized gas). This display is thinner than CRT and brighter than LCDs. It is normally is used in large range of TV like 30 inch or more. IBM built a monochrome plasma display in the 1980s that displayed orange letters against a black screen. A plasma display panel consists of millions of tiny compartments sandwiched between two panels of glass.  Each compartment or cell is arranged in groups of three, which are coated in phosphors colored red, green and blue subpixels, making it possible to produce over 16 million different colors.. Because of the charge needed to ionize the gas in the panel, plasma displays run hotter and consume more power than LCD and AMOLED panels. Plasma displays come in conventional PC displays sizes and also in sizes up to 60 inches for home theater and high definition television.

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