Fundamentals of Computer > Output Devices > Monitor and its Usage

CRT Vs. LCD Monitors

Monitor is the most important, popular and widely used soft-copy output device with which users interact most often. Two important hardware devices determine the quality of the image a monitor displays:

1. the monitor itself and
2. the video controller.

Types of Monitor:

Two basic types of monitors are used with personal computers:

1. CRT (cathode ray tube) type monitor
2. LCD (liquid crystal display)

• Either of these two type of monitors can be monochrome, grayscale (displaying varying intensities of gray against a white background) or color.

CRT Monitor:

• This type of monitor looks a lot like a TV screen that uses a vacuum tube as a display screen.

Merits of CRT Monitor:

• CRT monitor provides a bright, clear picture. In other words, its resolution is high.
• It is low in cost.
• Its viewing angle is wider.

Demerits of CRT Monitor:

• This type of monitor is big in size and large in weight, hence difficult to move.
• It needs comparatively much space to be fitted on the desk.
• It requires a lot of power to run; hence, it is not practical for use with notebook computers.
• Much more radiation emits from this type of monitor.
• It generates excessive heat.

LCD Monitor:

• It is a flat-panel monitor on which an image is created when the liquid crystal (that is normally transparent) becomes opaque when charged with electricity.

Merits of LCD Monitor:

• LCD monitor is small in size and light in weight, hence it is easily portable.
• Low operating power is required to run this type of monitor; hence it is widely used with notebook computers.
• There is no radiation from this monitor.
• It needs comparatively less space to be fitted on the lap or desk.
• It generates less heat.

Demerits of LCD Monitor:

• Image quality is not improved in this monitor, i.e. its resolution is poor.
• It is high in cost.
• It has a narrow viewing angle.

Differentiate between CRT and LCD Monitors:

Criteria	CRT Monitor	LCD Monitor
1. Have radiation?	Yes	No
2. Image quality (resolution)	Improved	Poor
3. Heat generation	Excessive	Almost no
4. Viewing angle	Wider	Narrow
5. Power consumption	High	Low
6. Size	Bigger	Smaller
7. Weight	Greater	Lighter
8. Cost	Less	More
9. Space required on the desk	More	Less
10. Portability/ Move	Difficult	Easy

Screen Clarity

Even if the monitor looks good, you need to check the following most important screen clarity specifications:

• Resolution
• Refresh rate
• Dot pitch

Resolution:

• Resolution is the degree of sharpness or clarity of an image.
• A monitor’s actual resolution is determined by the video controller, not by the monitor itself.
• Monitor’s resolution is determined by the number of pixels on the screen. The more pixels a monitor can display, the higher its resolution and the clearer its images appear.
• Though more items can fit on the screen at higher resolutions, but the items appear smaller, resulting in eyestrain and squinting.

Refresh Rate:

• A monitor’s refresh rate is the number of times per second that the electron guns scan every pixel on the screen.
• Refresh rate is measured in hertz (Hz) or in cycle per second. If a monitor’s refresh rate is 100 Hz, it means that the monitor refreshes its pixels 100 times per second.
• If the screen is not refreshed often enough, it appears to flicker, and flicker is one of the main causes of eyestrain.
• In general, a refresh rate of 72 Hz or higher should not cause eyestrain. Some monitors have different refresh rates for different resolutions.

Dot Pitch:

• In color monitor, every pixel consists of three dots- one red, one green and one blue. The distance between the like-colored dots of adjacent pixels on a color monitor is called dot pitch. In other words, if you measure the distance between the red dots of two adjacent pixels, you are measuring the monitor’s dot pitch.
• Dot pitch is measured as a fraction of a millimeter (mm). It can range from .15 mm (very fine) to .40 mm or higher (coarse).
• As a general rule, the smaller the dot pitch, the finer and more detailed images will appear on the monitor. That is, the highest-resolution monitors have the smallest dot pitch.
• A color monitor with dot pitch not greater than 0.28 mm is better.

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