Past Issues of Government Technology

Monitors Open Doors to Digital World

Better screens allow for panoramic views.

by / March 31, 1998 0
As far back as the 1850s, people tried to send images over telegraph wires, but the methods were not able to provide quality images and displays. In the 1930s, The Associated Press finally succeeded and began transmitting news pictures, and it had immediate success; people loved illustrations with their news.

Today, monitors make it possible to display pictures with amazing speed and quality; they have increasingly replaced hard copy as the preferred method of accessing text and images; and they have become our doors to the Internet and the digital universe.

SIZE DOES MATTER

One of the first things buyers notice about a monitor is its size. Cathode ray tube (CRT) monitors are the most common and are sold in 14-, 15-, 17-, 19- and 21-inch models. Fifteen-inch monitors are predominant in today's PC systems, with 17 inches being the most common upgrade.

Larger monitors can improve the way things look on your screen and keep graphics moving faster, which are the most common reasons for an upgrade. Smaller screens can be set for higher resolutions, but the result will be images that are smaller and difficult to read or distinguish.

However, larger screens have larger tubes that require more room, creating a problem for users with limited desktop space -- imagine having a 19-inch TV on your desk.

Quality 17-inch monitors cost about $700. Users can get a high-quality 21-inch monitor, ideal for desktop publishing or design, for about $2,000.

When considering a monitor's size, be aware that its size is not the same as its viewable or usable area. Manufacturers provide the viewable screen sizes, in addition to the CRT sizes, of their monitors. Since the picture tube is inside a plastic casing, the viewable screen size is smaller than the CRT or monitor size. For example, a 14-inch monitor can have a viewable area that varies from 13 inches to 13.5 inches, while a 17-inch monitor can range from 15.5 inches to 16 inches of viewable area.

Larger monitors require greater viewing distance. Ideally, users should sit at a distance that allows them to see the entire screen without severe head or eye movement -- 20 inches for a 15-inch monitor and 30 inches for a 17-inch monitor.

THE MONITOR BEHIND THE MASK

A CRT uses masks -- a shadow mask or an aperture grille mask -- to align the tube's electron beam on the color phosphors, which create the screen images.

Shadow mask monitors use dot pitch -- the distance between dots on a monitor -- as their measurements. The smaller the distance between dots the better the image. Dot pitch is measured in millimeters. For example a .28mm dot pitch will produce a sharper image than a .39mm dot pitch. Most monitors come with dot pitches of .25 mm to .28 mm. A shadow mask tube is less expensive to produce and more commonly used in the market. They offer displays with more precision for word processing and spreadsheet applications.

Aperture grille monitors are more expensive and provide better graphics with saturated colors and brightness, which makes them ideal for desktop publishing and design work.

CRAZY FROM THE HEAT

Larger monitors use more power and thus produce more heat and electromagnetic field (EMF) emissions. Power consumption can be as high as 128 watts when a monitor is active. But almost all monitors have a feature that activates a low-power or sleep mode, which can drop power consumption to 30 watts.

Even though the effects of long-term exposure to a monitor's EMF emissions has not proved harmful, there is concern among many users. However, the MPR II standard for EMF emissions provides the most stringent guidelines for maximum radiation levels.

IN NEED OF REFRESHMENT

Since many of us stare at monitors for up to 12 hours per day, a monitor with a low refresh rate -- the time it takes to redraw or redisplay an image on screen -- can cause eyestrain. A higher refresh rate reduces flicker and the resultant eyestrain and headaches. Screens with a refresh rate of under 70 Hertz (or Hz) -- the frequency of electrical vibrations per second -- are unsuitable, resulting in images and characters that appear to vibrate.

There is a trade-off between a high refresh rate and a high resolution. The higher the resolution, the more time that's required to refresh the screen. Resolution is the measurement -- usually in dots per inch -- of an image's sharpness on the screen. The more pixels -- small spots on the screen where a combination of dots is used to display text or images -- the higher the resolution.

VISIBLE TOUCH

Another type of monitor -- used in shopping malls and other public places -- are touchscreens. Touchscreen monitors eliminate the need for a keyboard or mouse and provide users with graphical icons to initiate specific tasks. It can be used by every user regardless of the user's computer knowledge. By simply touching the screen, users can request information, initiate transactions or paint and draw.

Touchscreens are also finding their way into liquid crystal displays (LCD). For example, Wacom Technologies has developed a pressure-sensitive LCD that allows users to directly paint onto the screen with a pressure-sensitive pen. The PL-300, developed by Wacom, is a 10-inch, stand-alone LCD monitor mounted on top of a Wacom tablet. The display has 800x600 pixel resolution and 256,000 color depth -- the number of colors that can be displayed at one time.

For additional information, contact ELO TouchSystems, MicroTouch Systems and Wacom.

NEW KID ON THE BLOCK

Today, CRT monitors are big league, while LCDs are the rookies. However, major monitor manufacturers -- ViewSonic, MAG Innovision, Princeton, NEC and others -- are introducing flat panel display monitors. LCDs -- one of the many forms of flat panel -- can not only match a CRT's viewable area and overall performance, but they are much lighter, have lower emission levels, are thinner and require less space on the desktop. Low power consumption and excellent resolution make them highly suitable for a variety of professional fields, such as desktop publishing, medicine, government, military and finance.

It is predicted that in a few years the roles might be reversed, and LCDs will push CRTs aside. Evidence of this changing of the guard is in the form of ViewSonic's VPA150 ViewPanel -- a 15-inch monitor that is multimedia-ready with stereo speakers built into the base.

LCDs are still expensive in comparison to a similar CRT -- about three to four times more than a CRT. The flat panel display market is growing, but it will still take years before flat panels overtake CRTs for desktop use.

In an effort to reduce LCD prices, some manufacturers are using passive-matrix technology, which is less expensive than active matrix (see glossary p. 65). Active matrix LCD displays for portable computers are clearly better than passive matrix displays. However, the differences are less noticeable in desktops; passive matrix LCD displays are quite readable and cheaper than active matrix models.

NEC's 14.4-inch MultiSync LCD 400V active matrix monitor weighs only 11 pounds, consumes 30 watts on full mode and less than 7 watts in the power-saving mode.

For additional information on LCDs, contact: ViewSonic, MAG Innovision, Princeton and NEC.

THE PLASMA ALTERNATIVE

Another alternative to CRTs and LCDs are plasma displays. Initially intended for portable computers, they are starting to appear in the desktop market.

Plasma displays can provide the quick response times of tubes with all the other advantages of LCD displays.

Plasma technology uses a sealed glass envelope filled with rows and columns of small, individually charged chambers. Each hold a mixture of neon and xenon gases, which, when energized, glow brightly and produce images.

Plasmavision, developed by Fujitsu, is a 42-inch monitor with its own remote control for setting the screen and switching between RGB -- a video display requiring separate red, green and blue signals -- and video.

The Leonardo plasma display, developed by Mitsubishi, provides a 40-inch monitor that's only 4 inches deep. It weighs 65 pounds and has a screen resolution of 640x480. Digital signal processing also allows the unit to display various resolutions accommodating an array of refresh rates. Leonardo is compatible with IBM, Macintosh third-party graphic standards and various video formats -- S-VHS, NTSC, PAL and SECAM -- but plasma monitors are still developing and very expensive.

For additional information on plasma monitors, contact Mitsubishi or Fujitsu.

WHAT TO LOOK FOR

Buying a new monitor and setting it up is the easiest upgrade to do, but keep an eye out for these features and issues:

* Inspect the adjustment or control keys, because they make a monitor easier on your eyes and easier to use. Most models provide screen control buttons for adjusting the picture and sound -- distortion, colors, pincushioning, zoom and volume.

* Set the proper resolution. After start-up, the computer will establish the default setting, but most units allow the user to set it as well. For a 15-inch monitor, the resolution should be 800x600, 17-inch 1024x768 and for 19-inch 1280x1024.

* Monitors and graphics cards are interrelated, so a user who upgrades to a high-quality 17-inch monitor but not the graphics card will see little improvement. Before upgrading to a larger monitor, make sure the monitor supports the card's capabilities and vice versa. It's crucial that buyers always check the manual for their monitor and cards to make sure they support the same resolution.

* Know the warranty details. Many manufacturers provide a three-year warranty with a new monitor. If you decide to purchase a reconditioned unit, look for a model with -- at least -- a one-year warranty.

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