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In this article:
- What are Computer Monitors
- Imaging Technologies used by Monitors
- Types of Display Interfaces
What are Computer Monitors?
A computer monitor or display is a common computer output device that interprets and shows the signals from a computer as images on a screen. Computer monitors are the only available output devices in most computer systems, especially in personal computers.
There are certain terms related to monitors:
- Resolution or Screen Resolution
It is the number of rows and columns of pixels that a monitor supports. The more the resolution, the higher is the quality of the display. Monitors today support a wide range of resolutions from as low as 320X200 pixels to as high as 3840X2400 pixels on some LCD displays.
- Refresh Rate
Refresh rate is the number of times a display is ‘refreshed’, that is, illuminated again in a second. It is measured in Hertz (Hz).
- Dot Pitch
Dot pitch is the distance between two same colored phosphor dots or between two triads of dots (a collection of three dots, one each of red, blue and green) and so also the size of the triad itself. It is expressed in millimeters (mm).
Imaging Technologies used by Monitors
Computer monitors use different technologies to produce the output they show. Some of these have been explained below:
- Liquid Crystal Displays or LCDs
LCDs are an advanced type of computer displays that have various electrons or crystals spread all over the screen. These are lightened up when an electrical charge is introduced to them. They have certain problems or challenges that are still to be dealt with which include the problem of the crystals not turning off when the charge is withdrawn.LCDs are the most popular display devices in the US today.
- Cathode Ray Tube Monitors
Cathode Ray Tubes or CRT Monitors are the most widely used types of monitors used with personal computers the world over. They were the earliest display devices and were so famous that all monitors including those that do not use an tubes are still sometimes called as “The Tube”.
- Plasma displays
Plasma Displays or PDPs are displays where a plasma discharge is sent between two flat glass panels that creates light as a result of excited phospors.
- Organic light-emitting diode
An Organic Light-Emitting Diode or OLED contains an LED which is a thin film having an emissive organic compound.
Types of Display Interfaces
- Computer Terminals
Computer monitors originated in th early large computer terminals. They were only capable of displaying text and did not possess any graphics. They were used to display only the important information that was required in order to fulfill a certain objective.
- Composite Monitors
Composite monitors were the first to offer color displays and were analog. As against VGA displays, they use a single cable to receive signals. They were used by the Apple II systems as well as the Commondore 64.
- Digital Monitors
Digital monitors, as the name implies, use digital signals in order to display the output on the screen. There are certain types of digital monitors as follows:
- TTL Monitors
These monitors used a DB-9 connector on the video cable and allowed the displaying of only 4 shades – Black, dim, medium and bright. They were available in a number of varieties the major ones being EGA, VGA and CGA. They supported a maximum of 64 colors and were available in monochrome as well as color avatars.
- Analog RGB Monitors
Analog RGB monitors are the most modern type of computer displays. They are capable of showing thousands or even millions distinct colors. These colors are formed by mixing the three primary color signals, namely, red, blue and green (hence the name RGB). They also make it possible to show varying intensities rather than limiting them to being dull, medium and bright.
- Digtial and Analog Combination
Some monitors combine the features of both digital as well as analog monitors. Though all digital monitors have had an analog signal as input, newer variants (especially LCD screens) now support digital signals as input. This is of recent origin and it is wrong to say that all computer monitors are digital.
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