Your Choices

Monitor Your Choices :

Even before you start to think about specific monitor features, you face some important choices. First, you must consider the size of the display that you need, and then the type of technology you wish to use.

Screen Size. Display size is specified in terms of the diagonal measurement of the screen. In general, the larger the display, the more information you can show at one time. It is important, however, to keep resolution in mind. A large display that is limited to low-resolution images cannot show as much information as a smaller display that supports a higher-resolution image.

For most office tasks, a 15-inch CRT (cathode-ray tube) is adequate. The extra cost of moving to a 17-inch CRT, however, may be well worth doing for Windows users, since it provides more space for multiple programs to be visible simultaneously. Specific applications can benefit from even larger displays: In desktop publishing, for example, it's helpful to have two full-size pages displayed side by side, as you can have with a 20-inch or larger display.

Also, keep in mind that Windows supports multiple graphics adapters, so it's possible and sometimes more practical to get more display area by using two separate displays-a solution that will often will cost less than the price of a single, larger display.

Display Technology. For desktop displays, your choices can be divided into two large groups: cathode ray tubes (CRTs) and liquid crystal displays (LCDs).

CRT Displays. A CRT relies on vacuum tube technology, which is based on principles developed more than 100 years ago. It's similar to the picture tubes used in a typical television set. Many important developments have evolved since then, resulting in displays that are brighter, have more accurate color, and support higher-resolution images. Design advances have also made it possible to reduce the overall size and weight of a CRT display.

CRTs are called "emissive" displays, because the light is created at the screen's surface by glowing phosphors. Three electron guns located in the back of the picture tube send streams of electrons toward the tube's front face. That surface is lined with red, green, and blue phosphors, which glow when excited by electrons. By controlling the strength of the electron beams, the phosphors glow with varying intensities, creating many colors. The electron beams are controlled electronically so that the speed and location can be adjusted, making it possible for a CRT to display images at different resolutions.

One important point to keep in mind is that the viewable image is never as large as the face of the CRT screen. This is because the size reported is actually the size of the tube measured diagonally--not the screen. So when you see an advertised CRT size, subtract one or two inches to get an approximate viewable area size.

CRTs can be divided into two main categories:

Shadow mask. The phosphors are arranged as circular dots with red, green, and blue triads covering the screen.
Stripe mask (aperture grille). The phosphors are arranged in vertical stripes. This is the design made famous by Sony Trinitron tubes, but other companies have their own variations.

LCDs. LCDs are transmissible displays, because they rely on a bright backlight, and the individual liquid crystal cells either block or transmit the light in order to create the viewable image. Generally, three liquid crystal cells are arranged next to each other to create a single pixel. The individual cells get their color from the light passing through red, green, or blue filters; almost all LCDs' filters are arranged in vertical stripes. LCDs fill the entire display area with an image, so the panel size is the same as the viewable-area size. This means that a 17-inch LCD will have about the same viewable area as most 19-inch CRTs, and a 15-inch LCD is equivalent to a 17-inch CRT.

LCDs are the standard for notebooks, because they are flat, lightweight, and require little power. These advantages in size and power make LCDs attractive for desktops as well. LCDs can be divided into two main categories:

Passive matrix. The liquid crystal cells are switched on and off at the edge of the panel by rows and columns. Often the panel is divided horizontally into two regions, creating what's known as a dual-scan display. Passive-matrix LCDs are less expensive than active-matrix LCDs, because they're much simpler to build and are rarely found in desktop LCDs. Instead, they are most often found in low-end, lesser-priced notebooks.
Active matrix. Also known as thin-film transistor (TFT) LCDs, because they have tiny transistors at every liquid crystal cell, Active-matrix transistors are used to turn the cell on or off. Because of the technology used, these panels are more expensive to make than passive-matrix LCDs. The upside is that the images are sharper, and the cells respond faster, making the displays suitable for moving images.

New-Technology Displays. There are also a couple of other technologies just over the horizon that eventually could have an impact on the market:

OLED. One of the most promising upcoming technologies is organic light-emitting diode(OLED) display technology. OLED combines some of the best features of the CRT and LCD worlds. Like an LCD, it is a flat-panel technology that's lightweight and consumes little power; it's similar to a CRT in that it's an emissive display, generating its own light at the surface, so the image quality is more like a CRT than an LCD.
Desktop rear projection. Another up-and-coming design is the desktop rear-projection display. Using the same tiny microdisplays found in portable data projectors, these displays are smaller versions of the familiar large, rear-projection television systems. They have a footprint similar to an LCD monitor and weigh only a bit more, but they support high-resolution screens of 20 inches or more diagonally--all at a more affordable price than CRTs or LCDs.