MONITORS THE OLD, THE NEW, THE FUTURE
Apr 1, 2001 12:00 PM
By CHARLIE R. PIERCE
Excessive heat buildup within a monitor will shorten life expectancy as much as a third.
All of today's digital and fancy interface designs cannot protect the CRT from heat. The only solution is to move past the CRT to flat screen technology. Quote Line Goes Here. Quote Line Goes Here.
If you have assumed that nothing has changed relating to monitors over the past five or 10 years, you're wrong. Some changes are obvious, some not-so-obvious.
OK, so let's start at the beginning ¡ existing technology. How does an analog video monitor work? Regardless of size, analog monitors all have one thing in common, the Cathode Ray Tube (CRT). The CRT is a vacuum tube that is designed to have a highly charged, phosphorous-coated face plate, electron gun in the rear, and an electro-magnetic yoke for control of electron flow. In the end, the CRT takes up room, causes heat, produces a potentially dangerous electro-magnetic induction (EMI) field, and wastes energy. Also these units tend to die in about two to two and a half years instead of the three to five years they are designed to last. Why is this? There are several reasons for premature CRT failure, and most of them are preventable. The first is improper setup of brightness and contrast. A second is heat, and a third is excessive dust or dirt.
For whatever reason, the average user of monitors tends to turn the brightness and contrast up all the way. The brightness control increases the voltage to the CRT's faceplate. The contrast increases the velocity of the electrons as they strike the faceplate.
The result is that the phosphorous coating on the CRT burns out prematurely and goes "soft" one, two or even three years too soon. To prevent the problem, you can do two things.
The first is to learn how to properly adjust your black-and-white (B/W) monitor using these steps:
As for the proper alignment of a color monitor ¡ even God has a problem here. The second method of preventing misadjustment of the brightness and contrast is not really a method at all. In reality it is one of the changes to the monitor design that I alluded to earlier; that is, many of today's monitors are going under the control of automated, digital controls. Therefore, no matter how hard you look, you will not find any knobs to adjust brightness or contrast. Adjustments are handled completely by the digital circuitry within the monitor, thus ensuring an even, consistent image. Such digital circuitry also extends the life of the CRT.
The second major factor in the life expectancy of monitors is heat. Excessive heat buildup within a monitor will shorten life expectancy as much as a third. Here is something that never ceases to amaze me: If you were to place a monitor in the middle of a table (that had nothing else on it), someone would eventually place a newspaper, magazine or file on top of the monitor (even though there is plenty of open table to set the paper down on). So what's the big deal? The action of the CRT and involved circuitry creates a lot of heat. You will notice that all smaller monitors have metal bodies, while larger monitors have slotted cover designs. The metal bodies act as heat sinks to absorb and dissipate the excessive heat created by the CRT. The slotted bodies allow for natural air flow throughout the monitor caused by the heat rising and pulling in cooler air.
Paper is well known to be an insulator ¡ª because of the fiber texture of the paper. Consequently, the stacking of paper articles (even a single sheet of paper) on a monitor will insulate it, causing the internal heat to rise as much as two-thirds above specification.
Net result? Knock off one third of the life expectancy of the monitor. It's a key lesson! Keep all paperwork off the monitor and allow for proper and adequate ventilation. The same also holds true for stacked monitors. You must provide for adequate, if not increased, ventilation, which is usually accomplished with the use of muffin fans. Unfortunately, all of today's digital and fancy interface designs cannot protect the CRT from heat. The only solution is to move past the CRT and get involved with flat screen technology.
The last of the great enemies of the standard monitor is excessive dust and dirt. Because of the technology of the CRT, monitors and televisions are natural dust magnets. Have you ever noticed how the screen of your monitor, television, or computers are always dusty? It is because of the electron crash that is happening on the other side of the glass. Equally, monitors will attract dirt and dust through every crack, vent or cranny in their housing. As the dust or dirt builds up on the inside, it acts as an insulator and causes the unit to run hotter than normal. The consequent strain to the various components within the monitor will suck the life out of it. What can you do? Keep your working environments as clean and dust-free as possible.
OK, so we have now discussed the existing technology of monitors and the most common reasons for their failures. Now let's look at the modern world and where we are going, which is solid state. We are moving past the antiquated CRT and now are producing the flat-screen technology through Liquid Crystal Display (LCD). It's exciting and available. So what is it? Imagine a full size monitor that is less than 4 inches thick, full color, high resolution, and can hang on a wall like a picture. This, by itself, is a huge step forward. The most obvious reason is the size and how little space it requires. It's a huge boon to the monitoring room; regaining a couple of square feet of lost space is always a godsend. However, gain one thing, lose another.
Flat screen is not new technology; it has been around for the past 10 or 15 years. It is fairly new to our industry, however, and has been held back by several factors, cost not being the least of them. Other major holdbacks have been screen size and image resolution. As with anything else involving CCTV, you tend to get what you pay for. The better the quality and/or the bigger the screen ¡ the bigger the buck. However, in the past couple of years, there have been quantum leaps in the overall development and availability of these screens. We are now seeing them advertised everywhere, and the cost is coming down hard and fast. Screen size is still a consideration. For the most part, the majority of the flat screens being pushed into our industry are 2-, 3-, 4-, 5-, and 9-in. screens ¡ª the perfect size for executive desktops but not for continuous monitoring stations.
There are 12- and 17-inch screens out there, but you need to look a little harder to find them and, of course, they cost more. So what advantages and/or disadvantages do the new LCD units offer that would make you want to switch or stay? Here are some:
Charlie R. Pierce, president of LRC Electronics, Davenport, Iowa, is a leading authority on CCTV and a regular contributor to Access Control & Security Systems Integration.