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You can use a good monitor for years and attach it to different PCs and graphics cards as you upgrade. And as you spend all your time looking at the monitor when working on the computer, this is one area where it pays to spend extra for the highest-performance model you can afford. In this guide, we show you the types of technologies and features to look for when purchasing a new display.
There are a few major decisions to make before searching for monitors. First, you need to know if you want a traditional monitor, which uses a cathode-ray tube (CRT), or a digital flat-panel display. Most of the flat-panel monitors affordable enough for consumer use employ liquid-crystal-display (LCD) technology.
When it comes to monitors, size is important. We strongly discourage you from buying anything smaller than a 17-inch display in the CRT category. For LCD monitors, we recommend that you buy one with a native resolution of more than 1,024 x 768 pixels.
Know exactly how much you're willing to spend on a new display. If your upper limit is $300, you can eliminate flat-panel displays from consideration. The toughest decisions fall on users with a lot of money to spend, as the purchase becomes a question of buying a large-screen CRT monitor or a moderately sized flat-panel display.
The most common-selling monitors use CRT designs. Current CRT displays are bright, offer stunning color output, and represent an incredible overall value compared to flat-panel monitors. A CRT is a funnel-shaped vacuum tube that has an electron gun in the narrow end at the rear of the display, and a coating of phosphors on the large end. The phosphors are arranged in clusters of three, called pixels, with one red phosphor, one green phosphor, and one blue phosphor per pixel. Electrons from the gun excite these phosphors, causing them to glow at different intensities and create the images we see on the screen. Since the light from a CRT issues from the very front of the display and has to pass only through a layer of glass, CRTs can be extremely bright. This lighting setup also makes it easy to view a CRT display from the side.
Shadow masks and aperture grilles
Electron guns are not perfect, so manufacturers use a "shadow mask" to prevent stray electrons from accidentally exciting nearby phosphors and causing image degradation. Shadow masks are metal screens that fit around the phosphors and deflect the rogue electrons.
Many displays use Trinitron or Diamondtron technology. In these displays, pixels are arranged in vertical stripes. These designs rely on the precision of the electron gun for horizontal separation, so the mask (called an aperture grille in these displays) only has to keep the vertical stripes separate. Aperture grilles require half as much metal as traditional shadow masks, so the end result is that they block fewer phosphors and that the display can be extremely bright with vivid colors and excellent contrast. You can tell if a monitor uses an aperture grille by looking for a thin horizontal line a few inches from the top of the screen and a few inches from the bottom that resembles a pencil mark. This is the shadow cast by a thin damper wire that keeps all the vertical aperture grille "strips" from moving around.
Some monitors have Invar shadow masks. Invar is a special alloy that resists expansion when exposed to high temperatures. This allows displays with Invar shadow masks to run at higher brightness settings with better contrast since the mask is less likely to expand and cause image distortion. Because image quality has more to do with overall engineering quality than the use of an exotic alloy, don't hesitate to buy a display without Invar if you like its output.
Dot pitch and stripe pitch
Dot pitch is the amount of space, in millimeters, that separates two phosphors of the same color. If a monitor has a dot pitch .22, there are 0.22 millimeters from one red phosphor to the nearest red phosphor in an adjacent pixel. Smaller is better in this instance, and you should try to find a display with a dot pitch .25 or less.
If you see a specification for stripe pitch instead of dot pitch, the monitor is using a Trinitron or Diamondtron tube. Stripe pitch is the distance, in millimeters, between two like-colored stripes. Lower numbers are better, but a stripe pitch .22 is not necessarily better than a dot pitch .25. The two values shouldn't be directly compared.
The major selling point of flat-panel displays is their size. Traditional CRT monitors are a foot deep or more, so they take up a lot of space on a desktop. Flat-panel displays are only a few inches deep, making them great for normal desktops and even better for cramped quarters such as cubicles.
Another nice aspect of a flat-panel display is its digital nature. When you use this display in an all-digital environment, you can get terrific accuracy in imaging. For example, if you send a digital signal for a certain shade of green, your monitor will always produce that precise shade of green on the LCD display. CRTs, on the other hand, are less accurate.
LCDs are backlit, and that light has to pass through a few polarization filters and other layers before it finally emerges from the front of the display. This is why most LCDs are not as bright as a good CRT. It also explains why LCDs are practically illegible when you view them from any angle other than the straight on.
Flat-screen CRT versus flat-panel display
Some CRTs are advertised as having a flat (or flat square) screen but this isn't the same thing as a true flat-panel display.
Older CRTs have a pronounced curvature to their screens. This allows the electron beams to travel the same distance to each phosphor. Like a flashlight beam, electron beams disperse over a distance, and using a truly flat screen could lead to distortion at the edge of the display. For this reason most older CRT displays represent a section of a sphere, where all points are equidistant from the origin of the electron beams. Trinitron tubes (and other displays that employ an aperture grille) represent a section of a cylinder, meaning they are flat vertically but curved somewhat horizontally. This explains why images from these types of devices sometimes seem concave.
Advances in technology allow for tighter electron-beam focus over longer distances in the newer CRT screens. This allows the source of the electron beams to be farther from the edges of the display than from the center. These newer CRTs still represent a section of a sphere, but the sphere is just very large so that the display appears nearly flat to a user. Some manufacturers have augmented this effect by affixing special glass plates to the front of the tube. The glass reverses optical distortion near the edges of the screen so the final image projected to a user's eyes appears flat and crisp from corner to corner.
True flat-panel displays rely on none of this optical trickery. For example, in a TFT LCD, the light source behind the display illuminates each pixel equally and constantly, so the design doesn't need to incorporate any curvature. The bottom line is that flat-panel displays really are flat.
Viewable image size
The monitor screen sizes listed in the brochures aren't entirely truthful, at least where CRTs are concerned. Screen sizes are measured diagonally but CRTs have a plastic bezel that covers up the very edges of the display. This can shave a half-inch to a full inch from the actual viewable image size.
Listed LCD screen sizes generally are accurate, so a 15-inch LCD is closer in viewable image size to a 17-inch CRT than a 15-inch CRT.
A monitor's resolution is the number of pixels displayed in a horizontal row times the number of pixels displayed in a vertical column. A resolution setting ,024 x 768 indicates that 786,432 pixels are available to create an image. More pixels allow for finer detail, making higher resolutions inherently better than low resolutions. High resolutions also provide you with a larger usable display area.
Don't pay any attention to CRTs with small screen sizes that claim high resolutions are possible. Even if a new 17-inch monitor might be capable of a resolution ,600 x 1,200, you'll never use it. A screen that small running at such a high resolution would display microscopic text, tiny desktop icons, and take such a hit in image quality that it would be of no practical value. The upper usable limit of a 17-inch monitor usually is 1,280 x 1,024, but many users run them at 1,024 x 768. A reasonable upper limit for a 19-inch CRT is 1,280 x 1,024. You can run a 21-inch monitor successfully at 1,600 x 1,200.
Flat-panel display resolution works differently. LCDs and most other flat-panel technologies have a fixed resolution. When you select a resolution that is outside the native resolution, image degradation occurs. LCDs are notoriously poor at enlarging and shrinking images, so you should buy one only if you plan to work at the same resolution all the time.
The maximum number of colors a display can produce at once is called the color depth. Color depth is measured in bits per pixel. CRT displays can handle at least 24-bit color depths, meaning that over 16.7-million simultaneous colors are possible. This is the equivalent of photographic-quality output, although low resolutions can hamper color fidelity. If your video card is up to snuff, you'll have no worries about color depth with a CRT display.
Most LCDs are capable of only an 18-bit color depth, or slightly more than 262,000 simultaneous colors. Some new designs can simulate 24-bit color. This is something to consider if you plan to play games or work with images that use 24-bit or higher color depths.
The refresh rate, measured in hertz, is the number of times per second the screen is entirely redrawn. Turns out that when you hit the phosphor it takes a while for the light to decay. So the phosphor decay rate needs to be matched to the graphics card refresh rate. If the phosphor decay is too fast for the graphics card setting the screen will flicker.
So why do you want a fast refresh rate? Turns out if the phosphor has a long decay rate the image smears as things move across the screen. To minimize the smear, refresh rate needs to increase and a phosphor with less persistence needs to be used. Flicker, causes eye fatigue and possibly headaches. Smearing depending on your needs is not desirable. There is a third element that has to do with florescent lights. These lights beat at a certain frequency also and its nice to not have the monitor and lights beating at the same or near the same frequency.
Through all this together and you want a monitor that supports a refresh rate Hz or faster at the resolution and color depth you plan to work with. If you're thinking about a 17-inch monitor, check the maximum refresh rate at resolutions between 1,024 x 768 and 1,280 x 1,024. Before purchasing a 19-inch or larger monitor, investigate the refresh rates that the monitor supports between resolutions ,280 x 1,024 and 1,600 x 1,200.
If you are buying an LCD display, forget about the refresh rate. Because of the way LCD technology works, it can provide stable images at 60 Hz, and sometimes less.
CRTs are analog devices, so they connect via an analog interface. Although some CRTs now have digital interfaces, in the end, you still have to convert the digital signal to an analog signal.
All LCDs are digital devices, but until recently, they universally employed analog interfaces. This was because, in the past, all video cards were designed for use with CRT monitors. The video card sends digital information to its digital-to-analog converter (DAC), which transmits the resulting analog signal down the cable to the monitor. CRTs can use this information as-is, but all-digital LCDs must run the analog signal through the monitor's analog-to-digital converter. This can lead to image degradation. Try to find an LCD that uses a digital interface, but make sure you have a video card capable of digital output, or the display will suffer.
Some people panic when they buy an LCD display and find that it has very few controls. This is one area where less is better and more controls simply mean there are more possible defects to fix. As LCDs are digital, you don't have to worry about adjusting for convergence (when three separate electron beams converge on a single pixel in color CRTs; misconverged beams can cause a fuzzy picture), barreling (distortion near the edges of CRT displays that occurs when vertical lines bow outward), pincushioning (when the left and right edges of the display bow inward), rotation (when the entire display is not level on the top or bottom), or similar flaws that afflict CRTs. (If you do have to worry about these things, return the LCD.)
Onscreen display (OSD)
If you purchase a CRT or an LCD with controls, make certain it has an onscreen display (OSD). The OSD is a menu that pops up on the display, allowing you to choose the types of adjustments you want to make. The greatest benefit of an onscreen display is that it provides feedback when you make adjustments. Instead of turning a contrast dial and viewing the changes, the OSD lets you see exactly how much change you are applying. For example, if you initialize the OSD and call up the contrast setting, you see a number, such as 60, that gets bigger or smaller depending on the adjustments you make. If you find an exact setting that looks good, just remember the number. You can then explore other settings, knowing you can always go back to the setting you liked.
OSDs usually indicate if a monitor has some advanced memory features. Inferior monitors with analog controls require you to adjust the screen each time the resolution changes. If you are using a monitor with memory, you establish the settings the first time the resolution changes. The monitor then automatically applies those settings each time you use that resolution. This saves a lot of time and, fortunately, most monitors have this ability.
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