Digital Trends

Introduction

Whether you're in the market to replace the hulking CRT that is making your desk sag or you're planning on purchasing a laptop, some knowledge of LCD technology will help you make a better decision.

Unfortunately, the contradiction of today's Liquid Crystal Display (LCD) technology is that bigger often means smaller. And as a result, consumers who think a bigger screen will be easier on their eyes are often disappointed in their purchase.

LCDs vs. CRTs

LCD monitors are some of today's hottest computing and consumer electronics products, and for good reason. They take up less room than traditional Cathode Ray Tube (CRT) monitors, weigh much less, consume far less power, are much easier to read text on, and let's face it — they just look cooler. However, there also are a few drawbacks to LCDs, including a slower response time, a reduced viewing angle, a higher price and the fact that they have only one optimal resolution.

The last point is an important one, and something that first time LCD or laptop buyers need to understand.

If you're used to CRT monitors, you probably know a little about screen resolution. The higher your resolution, the more screen "real estate" you have and as a result, the smaller things will appear. This is because at higher resolutions, more pixels are viewable. Since each image or part of the screen is made up of a set number of pixels, if you are able to fit more pixels into the same physical area of screen, the image will appear smaller.

This is normally not a concern with CRT users, because CRTs can be resized to larger or smaller resolutions with no problem.

The Designtechnica review page shown in 800 x 600 resolution (left) and 1280 x 800 resolution (right).

The main issue with changing the screen resolution on a CRT monitor is that it affects the refresh rate. The refresh rate refers to the number of times that the screen redraws the image every second. Since there is always movement on your screen, the image needs to be redrawn quite often for it to appear that it is in motion.

Typically, the optimal refresh rate for a CRT monitor is 75Hz, meaning that the image is redrawn 75 times every second. The highest you'll need is 85Hz, and some people can tell the difference between a 75Hz and 85Hz refresh rate. Anything higher than 85Hz generally won't be noticeable and can also be dangerous to your monitor, as some people have the tendency to push their monitors to refresh rates beyond what they were intended to use. Anything lower than 75Hz and you may notice a flicker of the image as it refreshes.

Too low of a refresh rate is a common occurrence and is often a major case of tired eyes and office fatigue. "Power users" will tell you they will often sit down at other people's workstations and notice right away that the refresh rate was too low for comfort.

When dealing with LCDs, refresh rate is not much of a concern since they use a different technology to draw the image. Refresh rates as low as 40Hz or 60Hz are perfectly acceptable with LCD monitors.

What is important is the concept of response time — the time in milliseconds it takes for the screen to update the pixel colors. This is a big deal because a slower response time will give the illusion of "ghosting" — the effect of pixels not updating with new information fast enough, so that a trail is left behind a moving object. This usually happens in high action movies or games and is one of the main reasons why LCDs are often not recommended for gamers. This is changing however, as displays with 20ms — which are just fine for gaming - are becoming more prevalent.