LCD MONITORSWhat is LCD?
Short for liquid crystal display, a type of display used in digital watches and many portable computers. LCD displays utilize two sheets of polarizing material with a liquid crystal solution between them. An electric current passed through the liquid causes the crystals to align so that light cannot pass through them. Each crystal, therefore, is like a shutter, either allowing light to pass through or blocking the light.
What are LCD Monitors?
An LCD monitor is one that uses LCD (defined abve) technologies rather than the conventional CRT technologies used by most desktop monitors. Until recently, LCD panels were used exclusively on notebook computers and other portable devices. In 1997, however, several manufacturers began offering full-size LCD monitors as alternatives to CRT monitors.
Why use LCD monitors?
So, now that you understand what LCD monitors are, we can now start to look at some of the reasons why LCD monitors are so great. The list of items below show some of the advantages to owning an LCD monitor.
BRIGHTNESS - The typical ViewSonic LCD monitor has a brightness of 250 to 300 nits, compared with a typical CRT brightness of 100 units. Since an LCD acts like a shutter, it can be made brighter by increasing the brightness of the backlight. However, when the beam current of a CRT is increased to boost brightness, the beam spot size also increases, which lowers effective resolution and may yield a soft or fuzzy image.
NO FLICKER - There is no flicker on an LCD display because, while a CRT must be refreshed, the LCD has a constant source of light over the whole screen. Once a pixel is on, it stays on until turned off.
FOCUS - In a CRT, the electron beam is circular when aimed directly forward, but becomes distorted when aimed up, down, left or right as it sweeps across the screen and may cause image clarity or focus issues at the screen edge. In contrast, an LCD has millions of pixels, each one effectively independent from its neighbor, with no scanning electron beam, so distortion problems are negligible. The image is always perfectly "focused" over the entire screen.
PERFECT GEOMETRY - LCD monitors provide geometrically perfect, distortion-free images-a huge advantage for advanced users such as artists and designers.
LONGEVITY - The only item that ages on an LCD monitor is the backlight, which is composed of one or more tiny fluorescent tubes. The typical life of a backlight is 50,000 hours to the half brightness point-the point at which brightness is one-half of the original brightness, and the industry standard measure for product life. A CRT ages in two ways: An oxide layer forms on the cathode of the electron gun, decreasing beam current; and the phosphor ages and becomes less efficient. The typical CRT half-brightness point occurs between 10,000 and 20,000 hours.
POWER CONSUMPTION - The power required to run an LCD is about one-third of that required for a CRT with the same screen area. In addition, the amount of heat generated by an LCD monitor is considerably less than a CRT monitor, resulting in a lower load on air conditioning. Building cooling needs may be decreased by up to 20%. And, if an LCD monitor is used with an uninterruptible power supply, the lower power required provides precious extra minutes to store critical data and shut down gracefully in the event of a power failure. These power-saving features of LCDs reduce the total cost of ownership.
LOW EMISSIONS - An LCD is essentially emission-free, while a CRT monitor can generate electric, magnetic and even X-ray emissions due to the high-voltage power supply necessary to drive the CRT. An LCD causes no electromagnetic interference.
ERGONOMICS - The size, dimensions and weight of an LCD allow it to fit into locations that a CRT can't—even mounted on a wall. An average 17" CRT monitor may measure almost 17 inches deep and weigh up to 40 pounds, while an average 17" LCD takes up half the space, with a depth of just around 8 inches and a weight of 15 pounds. In addition, some LCDs can also pivot from landscape to portrait mode to enhance certain applications, making it easier to work on spreadsheets or two-page layouts, for example.
TOTAL COST OF OWNERSHIP - LCD prices have been decreasing in recent years. When the total cost of ownership is considered-including savings in power consumption and lifespan-LCDs are now less expensive than many CRTs.
What are some drawbacks of LCD Monitors?
LCD monitors are not all as good as you might think. The following list will show some the disadvantages of owning an LCD monitor.
COST - Although the cost of owning an LCD monitor is dropping, the market right now still views the LCD monitor as a new technology. So the price of LCDs is still quite high for the average PC user.
FRAGILE - Since these monitors are much thinner than CRTs, the are lighter, but this means that there is a greater chance of damage to the monitor. For example, if a tennis ball is thrown at a CRT monitor, in most cases no damage will occur, but if the same ball is thrown with the same speed at an LCD, the chances of damage are much greater.
LIMITED VIEWING ANGLE - The physical structure of LCD pixels can cause the brightness and even the color of images to shift if you view them from an angle rather than facing the screen directly. Take manufacturer's specifications with a grain of salt and make your own observations if possible; viewing-angle issues become more critical as panel size increases.
IMAGE QUALITY - Image quality may be greatly reduced when running in nonnative resolution, because the image must be scaled to match the pattern of physical pixels.
OTHER DISADVANTAGES - Color rendition may be limited or inconsistent, Moving images may smear, May flicker from inability to synchronize with signal correctly.
What is CRT?
Abbreviation of cathode-ray tube, the technology used in most televisions and computer display screens. A CRT works by moving an electron beam back and forth across the back of the screen. Each time the beam makes a pass across the screen, it lights up phosphor dots on the inside of the glass tube, thereby illuminating the active portions of the screen. By drawing many such lines from the top to the bottom of the screen, it creates an entire screenful of images.
Why use CRT monitors?
Although these monitors are of ancient technology, they do come with a couple of benefits that cannot be found in LCD monitors. Here are a few of those advantages:
ACCURATE COLOR - CRTs can provide richer color in a fuller spectrum than most LCDs. In general, graphic artists prefer CRT monitors because they show truer colors and greater nuance-particularly useful for preparing files for printing and for using photo applications such as Adobe® Photoshop®.
RESPONSE TIME - CRTs may respond more quickly than some LCDs to videos and fast-action games. For some LCDs, pixels respond to voltage (being turned "on" and "off") more slowly than the time it takes for an electron beam to redraw a CRT screen. As a result, fast-moving images can sometimes leave visible trails, called ghosting, or appear blurry on an LCD. ViewSonic ClearMotionTM LCDs have virtually eliminated response-time issues.
VIEWING ANGLE - CRT monitors display good brightness and color from a wide viewing angle. Some LCDs, however, look their best when you are directly in front of them, because of the way light passes through liquid crystals in the screen. Keep in mind that LCD technology is rapidly developing, increasing LCD viewing angels, so this CRT advantage doesn't hold true in every case. Check the specs of the monitors you're considering. ViewSonic XtremeView® LCDs have superior viewing angles.
MULTIPLE RESOLUTIONS - CRT monitors can switch between multiple resolution settings without a significant loss in sharpness. If you need to change your monitor resolution frequently, you may be better off with CRT technology.
LOWER PURCHASE PRICE - CRT monitors are generally less expensive at initial purchase than LCDs
What are some drawbacks of using CRT Monitors?
Don’t go running off and buying a big old CRT just after reading those advantages, you might want to take into account the following factors, which come from the dark side of CRT technology!
SIZE - Unlike LCDs, these CRT monitors are very heavy, and much bulkier. This means that they will require much more space than an LCD. So if space is a factor for you, then you may want to look at LCDs.
POWER - These monitors want nothing more but to eat as much power as they can. Typically a normal 17in CRT monitor will use 70W!
EMISSIONS - Their high-voltage electric field, high- and low frequency magnetic fields and x-ray radiation have proven to be harmful to humans in the past.
IMAGE QUALITY - The scanning technology they employ makes flickering unavoidable, causing eye strain and fatigue, sometimes the starin can be so great that it can lead to seizures, but this is a rare effect of using CRT monitors. If you have a past history of seizures or other visual related illnesses, you may want to consider LCD monitors.
IMAGE FIELD - Their surface is often either spherical or cylindrical, with the result that straight lines do not appear straight at the edges.
Which monitor should I buy?
So which is the better type of monitor to buy? It all comes down to how one will be using the monitor with their computer systems. CRTs are best suited for individuals who use it for desktop publishing, graphics development, gaming (and don't need portability) or are on a tight budget for buying a computer. LCDs are best suited for those individuals who use the computer heavily for word processing, programming or have limited desk space for the computer. As the technology improves with LCDs and the cost comes down more, LCDs will dominate the market and CRTs will remain for those who require them for specific professions. Just remember that monitors tend to outlive the functional lifetime of a computer system and can easily be used between systems, so it is best not to skimp too much when buying a display.
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