This guide will cover LCD specifications including Screen Size, Resolution, Pixel Response Time, Contrast Ratio, Brightness (nits), Viewing Angle, Inputs (DVI, VGA, Component, S-Video), and extras like USB ports, card readers, portrait and landscape views. Also a comparison to CRT monitors, and the Pros and Cons between chosing either.

Why LCD?

In the past CRT monitors have outdone LCDs for many reasons, but as interest pours into the LCD market due to their traditionally smaller size, lower energy consumption, and brighter screens, the technology is making them surpass CRTs in almost every way. Traditional hold backs on LCD monitors include viewing angle, which for CRTs is of course 180 degrees, resolution, contrast, and color. But these things have changed. Most LCDs nowadays have very wide viewing angles, the resolution is soaring, though still fixed for each monitor, and contrast and color have become very sharp and vivid. LCDs now outdo CRTs for almost every application. LCDs are great for saving space in the office or at home since a 23” LCD barely takes up any more space than the size of the screen, where a 23” CRT is enormous and takes up more space than on the normal desk. CRT monitors also consume much more power than LCDs which mean they dissipate a lot more heat, which could be an issue in hotter regions, or in places where there is sensitive equipment. CRT monitors also have a tendency to flicker, which can cause eye strain and make some people be able to use the computer for only a limited amount of time.  

When buying a new LCD monitor there are several things to take into consideration.

Of course you are already familiar with price, the lower the better right!

The next biggest concern is size.  Size is measured on an LCD screen diagonally across the viewing area. Because on an LCD screen the entire viewing area actually contains a picture, a 19" LCD screen has a larger display area than a 19" CRT monitor.

Fig 1: Screen Measuring

With this in mind it is important to consider the aspect ratio of the screen when looking at it's size. The aspect ratio is the dimensions of the width, compared to those of height. A screen with an aspect ratio of 16:9 is considered a widescreen, and are becoming more popular as they better represent the natural human field of vision than a 4:3 aspect ratio, or the traditional standard screen. 16:9 is also the official aspect ratio of HDTV, many DVDs have movies in widescreen format, and widescreen enables you to display more documents or applications on the same screen making multitasking easier.

Fig 2: Aspect Ratio

 A screen less than 17" is not worth buying unless its not for your desktop (like maybe inside your car). However, the larger the screen the higher the price, and, the slower the response time. In general, 30" is the largest the current market supplies monitors at, but they are very expensive right now. Of course, if you have a bigger screen you'll be able to view the screen from farther distances, making television viewing, or console gaming a possibility. For widescreen monitors 19" are best viewed from within 4.75 ft,  23" within 5.75 ft, and 30" within 7.5 ft.

Second to size is resolution. While LCD screens still have fixed resolutions, whereas CRTs can change resolutions, LCDs are starting to get resolutions beyond the maximum of CRT screens. LCDs can display smaller resolutions than their specific, or native, resolutions, but it can distort the image by having to compress the pixels resulting in color blending and a loss of sharpness. The point here is that if you do not have a video card(s) capable of meeting the resolution of a particular screen, you might as well buy a smaller one so that you can max it out. To compare resolutions to HD standards, for the moderate HD 720p a resolution of 1280x768 is satisfactory, but full HD1080i is considered to be comparable to a 1920x1200 resolution. Common native resolutions for LCD monitors are for 4:3 aspect ratio: 1024x768 (XGA) for 14"-15", 1280x1024 (SXGA) for 17"-19", 1600x1200 (UXGA) for 20"+. For 16:9 aspect ratio 1440x900 (WXGA+) for 19", 1680x1050 (WSXGA+) for 20", 1920x1200 (WUXGA) for 24", 2560x1600 for 30".

Fig 3: Display Resolution Standards

Buying a resolution capable of displaying HD standards is really only a concern if you plan on using your screen to display sources besides you computer. Many new monitors include inputs beyond just VGA of DVI inputs to include component, and s-video, which means you can connect an HD tuner, HD-DVD player, or next gen gaming console and work some serious graphics for many different components. However, consider the viewing distances found in the above screen size section when thinking about these possibilities.

Now that we have a general idea of the bracket of LCD screen we want for our application, let’s look at the make or break specs.

Response time is very important for gaming, and video applications, but for everyday work, it might not be such a big deal. Response time is the time it takes for a pixel to change from one color to another. This is important because if the response time is slow enough, then an effect known as ghosting can happen when the pixels fail to change fast enough leaving traces of older images in the new frame. Times for screens vary by size with larger screens generally having longer response times. Most response time are between 8 and 12ms, but superfast response times as low as 2ms are starting to emerge. In general for gaming or video purposes a response time of 16ms or smaller is necessary, thought the faster the better.

Fig. 4: Slow Response = Ghosting

Contrast ratio is given as a ratio of the brightness of a white to black pixel. For example a contrast ration of 1000:1 is pretty typical and means that a white pixel is 1000 times brighter than a black pixel. This is different to a CRT which has true black pixels. The reason LCD’s don’t have true black is because they are backlit so all pixels have some light coming from them. This is a spec that is traditionally pretty hyped up by manufacturers, though, its benefits have been questioned. In general look for monitors with a contrast ratio of 600:1 or better.

Somewhat related to the contrast ratio is the brightness which is measured in nits. This is simply a measurement of how much light a display emits. Most displays will have a brightness between 250-300 nits, but it depends on the application you want. Generally over 300 nits might be too bright for a desktop, though you can lower the brightness for desktop use and crank it up when you wish to watch a movie or play games from a little distance, 500 nits is a good rating for TV watching. If the monitor is less than 150 nits, reconsider buying it.

A big issue for some, but not for others is the type of connections a monitor has. Because LCDs are completely digital, the digital interface video (DVI) is the best input you can feed an LCD. If you send an analog VGA signal to an LCD it will have to convert it to a digital signal to display it. This is not too big a deal anymore since most LCDs can convert these signals fairly well. Most LCD’s will come with both a digital DVI and analog VGA input, but check to make sure you know what your computer can output, and what the monitor you want will accept before you buy.

Fig 5: DVI vs VGA
In addition to PC inputs, many larger displays will also have inputs for other components. Some monitors will have component, or s-video inputs allowing you to hook up components normally associated with a TV such as a DVD player, or gaming console. This could be an awesome addition to you entertainment center as the resolution of a computer monitor is generally much greater than that of a TV.

Fig 6: Component Video

Not so important to some is viewing angle. Most displays will have an adequate viewing angle for most purposes, but if you plan on crowding around you screen with several people to console game, make sure that this angle will work for you. 180 degrees is a perfect viewing angle, meaning it can be seen from directly sideways without color or brightness shifting.

Fig 7: Viewing Angle

Last but not least in the equation is the little extras. Because of LCDs size, and low power consumption they often offer many little extras to boost their functionality. Some LCDs can rotate so that they display in portrait format as opposed to the traditional landscape format, this simply reverses the aspect ratio say from 16:9 to 9:16. This can be useful for surfing web pages or viewing large spread sheets, but its not something you should pay extra for if you don’t think you’ll use it too much.  

Fig 8: Portrait vs Landscape
Another extra many monitors have is extra USB ports. Because the monitor will probably have some power to spare it can serve as a powered USB hub making it a lot easier to plug in your flash memory stick into the monitor as opposed to digging for it behind your computer. Similarly, some monitors will have a headphone jack to enable you to plug in headphones with out having to dig behind your computer. Other features a monitor could have include card readers for various memory types. These of course are all things that make a deal sweeter, though I wouldn’t pay too much extra for some of these functions.

            Now you have all the information you should need to attack buying your next LCD monitor. Go forth and conquer.

Here is a question I recived from another eBayer:

Q:

Thank you for your guide on buying LCD TV's. I have a novice question and was hoping you could answer. What is the difference between LCD TV and LCD Monitor for a computer. Can I buy one that will work for both? I want to use it for computer and Cable TV that has DVI connection on box.
Any info appreciated.

-nne_wholesale

A:

I'm glad I could help out!

The only real difrence btween LCD TVs and LCD monitors for computers tends to be
1) resolution
2) features and connection types
With LCD Tvs you generally get a much lower resolution than in computer monitors, but will get many more options as far as connection inputs, screen controls, and other functions you would expect of a TV such as a remote, and multiple inputs. Many LCD Tvs have computer inputs like VGA and/or DVI, however, you will be hard pressed to find a Computer monitor that has built in TV support such as Cable connections, or a remote.

Hope this answers your Question!

-Slingblade26