Liquid Crystal Display Monitors are slowly entering the world of Personal Computers. Although right now businesses account for most of the sales of LCD Monitors, this will slowly be shifting to home users as prices come down. For now, they are still much more expensive than CRT Monitors. Many people have been wondering whether they are really worth the price. To help you decide, we will show you how LCD technology works, and talk about some of the benefits over CRT Monitors.

One of Viewsonic's 19" LCD Monitors
© www.viewsonic.com, 2001
Modified by the TQ Team "Gates of Creation"

Liquid Crystal Displays are a bit more complicated that CRT Monitors. On the back of the screen is a fluorescent light which constantly lets out light. Right in front of it is a HPF (Horizontal Polarizing Filter). This filter only allows horizontal frequencies of light pass through (if light is moving at a different angle from the horizontal position, it will not be allowed through the HPF). Next, the light that does pass through goes through a layer of liquid crystals. Voltage is applied to the liquid crystals, and depending on how much is applied, the liquid crystals twist the light anywhere from 0 to 90 degrees. The more the light is twisted, the higher the intensity of the light.

Next, the light passes through a Vertical Polarizing Filter, which only lets vertical light through. The more the light was twisted in the Liquid Crystals, the more light is let through the Vertical Polarizing Filter to be used in the front of the monitor as a pixel.

Three individual streams of light are used to create one pixel on the LCD Monitor. The next step, after the light passes through the Vertical Polarizing Filter, is to let it pass through a red, green or blue color filter. Once this is done, three different colored streams of light are turned into one pixel and displayed on the screen. To help you understand this more, we have created an animation to show you what goes on in the LCD Monitor.

Full Screen

LCD Monitors also have a refresh rate, but it is not measured in the same way that it would be on a CRT Monitor. It is a measurement of how fast (in milliseconds) a pixel can change color. For an LCD Monitor, 25 milliseconds is very good. This means that it takes 25 milliseconds to refresh the whole screen. To measure how many times this monitor would be able to refresh the screen in 1 second, we divide 1 second by 25 milliseconds. 1000 milliseconds (which is 1 second) /25 milliseconds = 40. This monitor would be the equivalent of 40Hz on a CRT Monitor. As you can see, a typical CRT Monitor (60-75Hz) can refresh almost twice as fast as an LCD Monitor. Knowing this and the fact that our eyes can see 60 frames per seconds, we can see a very big disadvantage in this area. Playing games or watching DVD movies is therefore not as good on an LCD Monitor as it is on a CRT Monitor. With this in mind, lets take a look at some of the advantages of an LCD Monitor.

LCD Monitors have some very big advantages, especially for small and large businesses. Although the initial cost is 3 to 4 times as much, in the long run it saves money. LCD Monitors use up to three times less energy than CRT Monitors. Another advantage is the size and weight. Since no large CRT Tube is needed, they are not more than 1-2" thick, and weigh much less than CRT Monitors