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How Computer Monitors Work

March 15th, 2010

computer-monitors.jpgIt allows you to see the world, to interact with millions of people, to study just about every subject known to mankind. It can be cube-shaped or flat, built-in or stand-alone.

Give up? It’s a computer monitor.

These devices are the keys that allow us access to the wonderful world of computing. Without computer monitors, you probably wouldn’t be reading this right now.

But many people don’t know how they work, or have been confused by overly technical explanations.

The truth is that they work differently depending on what type of monitor you have. It’s easy to figure out what type a monitor is. There are three main types in use right now: CRT, LCD, and plasma.

CRT Monitors

The “CRT” stands for “cathode ray tube”. These are the monitors many older people are familiar with. Big, blocky, and heavy, these have been around for decades and are still commonly used today, although they’re slowly being replaced in higher-tech companies and households. They are shaped like a cube on a stand, with a big block behind where the screen is. The actual screen surface may be gently curved in some models.

The screen of a CRT monitor is divided into millions of tiny squares. Each tiny square is called a “pixel”. To display an image, the monitor will change the color displayed in each pixel. The monitor is just showing you an image composed of thousands or millions of little pixels. To the bare eye, it looks just like a whole image. When a video or animation plays, these pixels change color very rapidly.

In the back part of the monitor, a lot of work is going on to bring you that picture. A metal filament is being heated in a vacuum, which produces a steady stream of electrons. This device is called a “cathoray tube”. Using electricity, the beam of tiny particles can be directed to specific pixels, just like a little laser.

This “laser” is redirected to one pixel at a time; it starts with the top left pixel, works its way across a row, and then down to the next row until it reaches the bottom right corner, where it starts again.

This might sound like it takes a long time, but in fact this laser hits each pixel 60-120 times each second! This is called its “refresh rate”. A monitor with a cathoray tube that hits a pixel 60 times each second has a 60 Hz refresh rate. A monitor with a cathoray tube that hits a pixel 100 times each second has a 100 Hz refresh rate, and so on.

LCD Monitors

The abbreviation “LCD” stands for “Liquid Crystal Display”. LCD monitors are becoming more common, as they are easier to move and look nicer. These are usually flat-screen monitors, and they are built into every laptop.

Just like a CRT monitor, the display is divided into millions of tiny squares, or “pixels”. The difference is that, rather than relying on a cathoray tube to direct a little laser at each pixel to keep it lit, each square acts as a tiny lightbulb of its own.

Each pixel has a small “LCD”, or “liquid crystal diode” (similar to an LED). Each LCD will change color and an image will be displayed, formed from combinations of thousands or millions of tiny pixels changing colors. Unlike CRT monitors, they change color of their own accords when directed to by the computer, rather than the cathoray tube controlling them.

The Computer

In the computer is located a part called the “motherboard”. In an expansion slot of this part is the “graphics card”, which tells the monitor what image to display.

When you look at a computer screen now, take a moment to marvel at the technology behind this piece of equipment that so many of us take for granted!

This article on how computer monitors work was supplied to us by Zabrina Way from Constant Content.

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