Computer Monitors

Principles of

Information TechnologyLytle High School

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Computer Monitors

Monitors are the screens you see with all computers.

What you see on the computer screen depends on the computer program you are running or what you are doing.

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Computer Monitors

Computer monitors are referred to in different ways by different people.

Some will refer to a monitor as the Video Display Unit, some will refer to it as a Computer Screen, or some even a CRT.

CRT is an older electronic term but is still in use. CRT stands for Cathode Ray Tube.

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CRTs

Believe it or not, computer monitors work in very much the same way as your television set at home.

Computer monitors have the same type of picture tube you find in television sets.

The picture tube in televisions is also a Cathode Ray Tube or CRT.

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Categories of Monitors

Just as computers fall into two categories, so do computer monitors.

Monochrome monitors only display one color. They may show the text in green, amber, or even black & white.

Color monitors show the graphic images in color.

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The Pixel

Electron beams are projected onto the back of the screen causing little dots of lights to glow.

Each little dot that makes up the picture image is called a Pixel.

At any given time, only one pixel is on. The others are all off. The light beams, or pixels, are turned on and off so quickly, light appears to be constant, causing the images to move about on the screen.

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Monitors ResolutionThe sharpness or quality of the picture image is called Resolution.

Picture resolution is dependent on the number of pixels shown on the screen.

The more pixels there are to each square inch of screen, the clearer, the sharper the picture image will be.

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Pixel

Computer Monitors

As technology changes over time, so does the quality of monitors.

As shown here, older monitors are low in resolution.

Monitors today have a much higher picture quality or higher resolution.

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The CGA Monitor

CGA monitors were the first color monitors to appear on the market. Since the technology was in it’s infancy, the picture quality was not very good.These monitors were capable of displaying 4 colors on the screen, at any one time.

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The first color monitors were CGA monitors. CGA stands for Color Graphics Adapter. These older monitors were low resolution.

The EGA Monitor

EGA stands for Extended Graphics Adapter. These were medium resolution monitors.EGA monitors evolved from enhancements done on CGA monitors.Since the technology was being improved, the picture quality is a little better than the CGA. These monitors were capable of displaying 16 colors on the screen at one time.

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The VGA MonitorVGA stands for Video Graphics Array. These monitors have a high resolution picture.

These monitors are capable of displaying 640 X 480 pixels per inch.

VGA monitors were capable of displaying 256 colors.

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The Super VGA

SVGA or Super VGA are extremely high resolution monitors. They are used where very high detailed and intricate pictures are needed.

Picture quality comes from a pixel st5arting at 800 X 600 dots per inch to as high as 1600 X 1200 dots per inch, depending on the monitor.

Super VGA monitors can display well over a million colors.

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Video Cards

Computer monitors come in a variety of resolutions and graphic capabilities.

As a result, a variety of video cards are available for computer monitors.

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Video Cards

A video card is a special printed circuit board with the electronics necessary to power the monitor and provide enhances graphic capabilities.

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Computer Monitors

You can not hook up an newer SVGA monitor to an older computer designed to work with an older CGA, EGA, or even a VGA monitor.

This used to cause problems for people who bought new computers thinking they could use the monitor from their old computers.

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Monitor Sizes

Monitors are measured diagonally (corner to corner) across the screen.

They come in a variety of sizes from 15” to 22” or even larger.

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17”

Monitor Sizes

15” 17” 20” 22”

There are also a variety of other sizes produced by different manufactures.

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Video Software

Aside from hardware considerations, monitors sometimes come with special software.

Software for the different monitors are called Video Drivers.

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Monitor Drivers

Just as monitors must be matched up with it’s matching video card, computers must have the proper software installed to make monitors work properly.

Sometimes, the software you are using like Windows 2000, Windows XP or certain other programs you use must have the proper video software driver installed in order to take full advantage of the monitors video capabilities.

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Dot PitchAnother term you will hear in regard to monitors is DOT PITCH.

Dot pitch is the spacing between the pixels and is measured in thousandths of an inch.

A .028 dot pitch is a higher resolution than a .032 dot pitch.

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Flat Screen MonitorsThe screens you see on laptop computers or today’s new flat-screen monitors are not a CRT.

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These computers and monitors use a Liquid Crystal Screen and operate on a totally different kind of technology.

You will also hear them referred to as Plasma monitors.

Flat Screen TVs

Today, there exists televisions with flat screens. They are flat enough and light enough to hang on the wall like pictures.

They are still more expensive than regular CRT televisions, ($2,000 or higher), and they come in sizes from 21” to 60”

However, as technology advances, costs tends to drop. When they were first introduced to the market, the cost was around $10,000.

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In Review

All monitors fall into two categories. Monochrome and Color

There are four types of color monitors. CGA, EGA, VGA and Super VGA

Monitors and video cards must be matched for optimum performance.

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In Review

Some monitors require special software, called a video driver, to operate properly.

Laptop computers do not use CRTs. They use flat screens filled with Plasma, which operate an a different technology.

Pixels are the little dots that make up the screen’s image.

Dot Pitch is a measurement of spacing between the pixels.

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Conclusion

This concludes your lesson on monitors.

I hope you found the lesson useful.

Be prepared to share what you have learned with others as we review what we now know about monitors.

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