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In recent years, flat-panel LCD (liquid crystal display) monitors have replaced the bulkier, traditional CRT (cathode ray tube) monitors for most computer users. Although CRT monitors are still available from vendors, they are being phased out by manufacturers. As the technology improves, the advantages previously held by CRT monitors have become less pronounced so that for most purposes, LCD / TFT monitors are now preferable to CRT.
Flat-panel LCD displays have been used for many years for portable computers, but are relatively new to desktops.
LCD refers to the type of display - a Liquid Crystal Display works by having two layers of polarised material with liquid crystal in between.
Each crystal is like a shutter, either allowing light to pass through or blocking the light off. LCD screens have given way to TFT mainly because of their lack of quality and refresh rates. A typical annoyance was persistence of vision which would be apparent on anything that moved across the screen. This behaviour was inadequate for games particularly but could be annoying on something as simple as scrolling text.
TFT (thin film transistor) was the solution and has been around for quite a while, however, up until recently it was much more costly. TFT uses a transistor for each pixel, and provides a much sharper image and higher refresh rate. As the technology has developed we are beginning to see higher and higher refresh rates to satisfy gamers in particular who might have seen the CRT still worth staying with for this reason. These refresh rates are usually contained in the specs and is worth noting when choosing a monitor for your system. See buying for more details.
For a more in depth view of the technologies involved you can find out more here.
A major advantage to LCD / TFT monitors is their size and weight. The depth of most LCDs ranges from about 1 to 3 inches in thickness, compared to CRT monitors that can be as much as 24 inches. LCD screens are therefore easy to move around and are small enough to be mounted on a wall. They take up very little desk space.
LCD screens cause less eyestrain and fatigue to the user than CRTs. The constant light barrage and scan lines of a CRT tube tends to cause strain on heavy computer users. The lower intensity of the LCD monitors, coupled with their constant screen display of pixels either being on or off, is less tiring.
LCD monitors are very energy-efficient. Most of the energy used by LCD displays is for the backlighting of the screen; the amount of voltage required to maintain the state of the various pixels as on or off is negligible.
A notable disadvantage of these displays is that they will darken / lighten depending on the angle you view them at. This can make it very difficult to work out which is the intended brightness level of the picture you are looking at. This is gradually being addressed but still remains a problem. See below.
A basic 15" LCD with a native resolution of 1024x768 pixels can now be bought for between £60 - £70. A 17" LCD monitor gives a native resolution of 1280x1024 pixels and costs from around £80 - £90. Expect to pay from £100 for 19" displays. You will need a 20" monitor for a native resolution of 1600x1200 pixels, costing around £150+. Widescreen monitors are now also becoming popular with resolutions up to 1920x1080 (full HIgh Definition), with 24" units costing around £300 - £350.
Additional features may include a USB hub, microphone and speakers. Some monitors incorporate a TV tuner, which allows the monitor to double as a standalone TV, but these are significantly more expensive.
A VGA (video graphics array) input means that the monitor can work with any PC, but a DVI (digital video interface) input gives potentially better image sharpness and colour accuracy. Note that a DVI-equipped graphics card is required to use this.
Native resolution: Because an LCD display uses a matrix of pixels to display its image, it has a "native" or fixed resolution at which the display looks best. A 15-inch LCD has a native resolution of 1024x768; most 17-, 18-, or 19-inch models use a 1280x1024 native resolution. High-end LCD displays may use 1600x1200 resolution. The native resolution should be one you are comfortable using for all your programs and applications. It may be possible to go lower (and in some cases higher), but the image is likely to appear blurry. Some models are better than others at handling non-native resolutions. If you need to change your monitor resolution frequently, a CRT monitor may be more suitable.
Refresh rates : Most monitor specifications quote a refresh rate. This is especially important if you are choosing a monitor that will be used on a gaming system. Typically you should aim for minimum of 16m/s. 12m/s and 8m/s is even better and becoming a popular choice.
Graphic monitors:
Some TFT screens are designed to suit graphic professionals, these generally provide much more acurate colour rendering, sharper picture and a much greater angle of viewing before brightness levels drop off. These will come at a price which may be twice as much as a similar monitor but for those that need it there is little choice other than to stick with CRT which still has the edge so far.
Dead Pixels: LCDs sometimes suffer from defective or "dead" pixels where one or more pixels remains permanently unlit, or black, when it should be activated and displaying a colour. Currently, the policy of manufacturers varies with regard to replacement. Some replace the LCD at the first sign of a dead pixel, but others wait until there are ten or more. It is worth checking the manufacturer's policy regarding dead pixels when considering buying an LCD display.
Although LCDs are usually very reliable, make sure you can return the display easily if it's flawed. The backlight is the part of an LCD most likely to wear out, so check to see how it can be replaced if necessary. Look for easy-to-reach front panel controls that are clearly labeled and for an easy-to-use on-screen menu.
Although now becoming obsolete, CRT monitors are still preferred by some gamers and for applications where colour quality is important. The colour clarity of CRT monitors can almost be matched by high-end TFT displays, which is by far the biggest advantage of CRT monitors over LCD. If you are producing artwork where colours and output are important a CRT has got to be still the number one choice. In time technology will produce an equivalent flat screen solution and for some they are already available at a fairly high cost. Precise adjustments can be made to the contrast, brightness and hues so that CRT monitors are better able to represent actual document colours. Screen resolution is not fixed as with LCDs either.
Currently the cost of a CRT vs a high end TFT is huge with CRTs being relatively cheap although more expensive to run.
Therefore the consideration comes mainly down to desk space and that little bit of extra quality. If you can afford the desk space there is little competition. The cost of saving real estate in this case is massive.
A good quality 19-inch CRT can be bought for under £150. CRT monitors often come with built-in additional features such as USB hubs and/or microphone and speakers. These can be useful in reducing desktop clutter, but sound quality in monitor speakers is likely to be poor.
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Inside LCD / TFTs
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