 | What are the advantages of LCD monitors? |
Technical Answer:
Most of the advantages of LCD displays are due to the fact that they were developed scores after the CRT was developed, incorporating many advances in technology that were made during the past decades. LCD stands for Liquid Crystal Display, a reference to the rotatable crystals that block (not emit!) light, which exhibit liquid-type properties. Their almost all-plastic construction makes them extremely lightweight, and the depth of the various layers involved is less than a fifth of the depth of a cathode ray tube, or CRT. This makes LCD's suitable for portable equipment where a large, heavy display is impracticable, such as a wristwatch. However, LCD's are quickly replacing CRT's in applications where where the CRT's weight is not much of a factor, such as office desktops. The reason behind this are the other advantages that LCD displays offer over CRT displays.
The method by which a CRT display creates images on the screen is composed of several processes, each of which is characterized by the transformation of one type of energy to another. Each time energy changes form, part of it (often over half!) is released in the form of heat. Thus, the CRT consumes a relatively large amount of power, as each process must make do with whatever energy was leftover from the last process. Of course, the power involved is not the only disadvantage with this method. The heat emitted must be dispersed to the ambient environment. This heats the room in which the monitor sits, requiring air conditioning and the power consumption that accompanies that operation.
In contrast, a liquid crystal display uses a cool florescent bulb to produce white light, and then blocks the portions of the light which are not required. As white light contains all colors, the filtration of 256 shades of red, 256 shades of green, and another 256 shades of blue gives us over 16 million (256 ^ 3 = 16777216) color combinations, in theory on par with CRT technology. The emission of florescent light releases very little heat, and no further heat is produced in the process. Most LCD displays also have an internal power transformer that emits heat, however, this is much less heat than the amount emitted by CRT display systems. The power and heat savings alone are reason enough to convince many people to switch to LCD monitors, especially in warmer climates.
Because the CRT must draw each pixel one-by-one, usually by scanning in horizontal lines, these devices suffer from 'flicker'. At refresh rates above 75 Hz, this is hardly noticeable. However, hours of sitting in front of these flickering displays often leads to eye strain, headaches, and fatigue. The LCD is immune to these phenomenon, as each pixel stays lit until it is time for it to change color. One last advantage of LCD displays is rather a technicality of CRT manufacturers inflating the apparent size of their displays in the past. A CRT in incapable of displaying an image right up to its edges. Despite this fact, the size of the display is measured diagonally from one outside corner of the physical unit to the opposing outside corner. The actual area that is capable of producing an image is naturally smaller. In spite of this, LCD displays produce an image right up to the very edge. Thus, a measurement of the physical device is parallel to a measurement of the image that it produces. Thus, the image that a 17 inch LCD monitor produces is larger than the image produced by a 17 inch CRT. In general, 10%-15% of the size of the monitor must be subtracted from a CRT to accurately compare it to a competing LCD model.
Liquid crystal displays are not without their disadvantages, however. Cost is almost always a factor in the purchase of any equipment. Although the operation of an LCD display costs less in terms of electricity, the device itself can cost over twice the price of a comparable CRT display. It would take many hundreds of hours of operation for an LCD monitor to 'pay for itself' in terms of cost savings.
Another disadvantage of LCD monitors is the fact that they operate on one specific screen resolution only. Known as the native resolution, it is a factor of the composition of the monitor itself, determined at the time of manufacture. This makes certain types of graphical and video work impossible. For the home user, games and movies must be interpolated, and hence might not display correctly. Another setback to the idea of watching movies on an LCD monitor is the narrow viewing angle that these screens provide. For one or two people watching a movie this may not be a problem, as they can adjust their sitting position and the position of the monitor such that they will always be inside the viewing angle. For anything more than a couple, however, the narrow viewing angle often makes movie-watching impossible on an LCD monitor.
If the interpolated images and narrow viewing angle were not reason enough to scare people away from viewing movies on LCD monitors, there are two other good reasons. While the 16 million colors that an LCD monitor can reproduce exceed the 10 million that humans can see, the CRT reproduces them more accurately. That is, the color produced by a CRT monitor is closer to the color intended by the software than the color produced by an LCD monitor. This is especially apparent in skin tones. Hopefully, the new color-calibrating LCD monitors will fix this. However, they are unlikely to fix the most apparent disadvantage for the LCD in this field- refresh frequency. LCD monitors do not scan the pixels in lines, thus the term refresh rate is inappropriate here. However, the pixels of course take a certain amount of time to switch color- much more time than a CRT rescans an image. The result is blurred motion, jagged edges, and 'ghosting' of moving objects. That does not make for an enjoyable movie experience.
Finally, the LCD monitor is much more fragile than the sturdy CRT monitor. While the large glass screen of a CRT may look frail, it is actually very strong and durable. Also, most of the CRT's internal parts are equally durable and long-lasting. The LCD, however, is assembled from fragile plastic parts. Of special interest are the pixels and the backlight. LCD monitors may have as many as 10 bad or 'stuck' pixels and still be considered fit for shipment by the manufacturer. A stuck pixel is one that does not light, or stays lit on a certain color no matter what the picture on the screen is. These bad pixels are not covered by warranty, thus it is important to check the monitor that you are purchasing at the store, before you leave with it. Also, the backlight is especially frail. The backlight often has its own separate warranty, and it is much more limited than the warranty on the rest of the device. Whereas the typical warranty for an LCD monitor is three years, the backlight is often covered for no more than one year.
Short Answer:
LCD, or liquid crystal display, monitors have thes...
Long Answer:
Despite being more expensive than CRT monitors, LCD monitors are quickly becoming the standard in...