Monitor Selection

Picking the correct monitor can really become a quagmire of competing specifications, costs, size, and don't forget what it tooks like. What brand? What refresh rates do I need? What do refresh and dot pitch have do with picture quality? How come small dot pitch and high refresh cost so much?

This same general properties are true of all monitors. Good, sharp, and high resolution costs more than softer looking and lower resolution units. Other features and quality factors only show up years later. For example, a lot of cheap monitors have poor phosphor on the tube but look OK when they are new. As they age, they get dimmer and dimmer. A high quality monitor is a major investment. Even a good, CAD level, 17" monitor can cost more than the PC it is connected to.

Keep in mind that high end monitors are only high end with an exceptional video card and proper cabling to drive it. For example, don't buy a Viewsonic P815-2 and expect it to look good with an old Diamond Stealth to drive it. The same is true for good video cards with a poor monitor. If either is weak, the screen will not be sharp, and it could be fuzzy or have faint ghosting.

What is Dot Pitch and how does it affect the image of a monitor?

Dot pitch is the diagonal distance between two phosphors of the same color. For example, the diagonal distance from a red phosphor dot to the next red phosphor dot. It is normally expressed in
millimeters (mm). Aperture grille tubes use stripe pitch or aperture grille pitch to measure the horizontal distance between its phosphor stripes.

Aperture Grille Pitch on a Slot Mask	Dot Pitch on a Shadow Mask

The smaller the dot or stripe pitch, the better the display. Images look finer and crisper when the dot pitch is smaller. Edges and lines appear smooth and refined. If you are considering a high resolution display, a finer dot pitch is important so images will be crisp. Because of the obvious differences, dot pitch and stripe pitch cannot be compared accurately. When comparing a dot pitch to an aperture grille or stripe pitch, allow some slack for the dot pitch. A given aperture grille pitch is roughly equivalent to a slightly bigger dot pitch. For example, a 0.25mm aperture grille pitch is roughly equivalent to a 0.27mm dot pitch.

What's the difference between a shadow mask vs. aperture grille?

The CRT (Cathode Ray Tube) mask is a major component of the picture tube. There are two major types of CRT masks: the shadow mask and the aperture grille, also called stripe mask. Both types of monitors produce excellent image quality. An aperture grille displays brighter images with richer and more saturated colors. Popular aperture grille technologies include SonicTron® from  ViewSonic®, DiamondTron® from Mitsubishi and Trinitron® from Sony®. On the other hand, a
shadow mask offers displays with more precision. Typically, they have a flat-square design which provides images that are more dimensionally accurate. Better shadow masks are made of INVAR, a type of alloy metal that has high heat resistance to withstand prolonged usage without distortion.

It is a matter of user preference and applications when selecting between shadow mask and   aperture grille monitors. For color graphics applications such as electronic desktop publishing, the aperture grille technology is often preferred for its ability to display colors more vividly. However, engineers doing CAD/CAM and other technical illustrators may prefer shadow mask technology for precision drawings and the better representation of flatter displays.

How about Refresh Rates? How are they related to resolution?

Refresh rates refer to the speed a screen is repainted or refreshed. The horizontal scan rate, expressed in kilohertz (kHz), is the number of lines that can be painted horizontally in one second. A higher horizontal scan rate leads to the ability to run higher resolutions. While the vertical scan rate, expressed in Hertz (Hz), tells us how many times the screen is repainted from the top line to the bottom line, per second. The higher the vertical refresh rate is, the less flicker you will notice, therefore less eye strain. The horizontal and vertical scan rates combine to provide the ability to
produce a high resolution, flicker-free image. As monitor resolution increases, the information displayed on the screen increases as well. So it takes more time to refresh a screen and the refresh rate decreases. Find out the refresh rate of the monitor in various resolutions, especially in the resolutions you plan to use. The standard for a flicker-free display is a vertical scan rate of 75Hz or higher.

What is Plug 'n Play? Why is it so popular?

Incorporated by Microsoft® through Windows® 95, "Plug and Play" was developed to simplify hardware installation. The basic idea behind Plug and Play is to design and develop hardware peripherals that can communicate with the operating system, identifying their requirements and functions to the system. Upon recognizing the new device, the operating system will configure it as part of the system. 

For monitors, Plug and Play does more than just facilitate a smooth and trouble-free installation. It may also enable users to change display resolutions and refresh rates of the monitor without the need to reboot the computer.

Video card

Good video cards for 19" or 21" CAD must have at least a 220-250MHz clock, 8MB of fast RAM, and be razor sharp at a minimum of 1600x1280 @ 72Hz refresh. 1800x1440 @72Hz or higher is even better. 4MB times 72 frames/sec is over 280MHz, so even a 220MHz isn't up to the task except at a 256 color pallet. Get 75Hz or higher if you can. Such choices are:

     Number 9 Revolution IV 16 or 32MB SRAM in either AGP or PCI      http://www.nine.com

     Number 9 SR-9 in 16 or 32MB AGP or PCI models, adds hardware DVD decoder and faster gaming

     Number 9 REV3D 8MB WRAM in either AGP or PCI, discontinued but still available

     Number 9 Imagine 128 Series2, discontinued but still available

     Intel Express 3D Graphics Card (740 AGP) (up to 1600x1280 only, slow)

     Matrox G200 16MB, or older Millenium II 8MB ( up to 1600x1280 only)

All of these 21" ( and the 19" PS790, PT795) monitors have a 3yr warranty. The PS790 is a deal in a 19" CAD tube.

* ViewSonic is offering an end-user mail-in rebate promotion on one of the hottest-selling monitors: the 19" (18" viewable) ViewSonic PS790, CAD quality display.   From June 15 through September 30, 1999, you will receive $100 cash back when you purchase a PS790 (limit one per customer). The $499 price is after the $100 rebate.

It takes a lot of complicated, finely tuned, electronics to focus electron beams down to .22 or 25mm, especially on big screeens. So, good CAD monitors tend to be rather expensive, and HEAVY. "If I don't get a hernia lifting it, it can't be any good." This is true for the CAD monitors. Monitors that only work up to 1600x1280 and wider dot pitch tend to be lighter and cheaper. 

For 17" and 15" viewing a lot wider and lower cost video card selection is available.

The higher end CAD monitors have a three year warranty. Actually, all of these do.

It isn't so obvious with the 21" glass, but it is with the 17" models. Lower cost monitors have lower resolution, bigger dot pitch, and lower refresh rates.

The Viewsonic GS771-2 and the Panasonic SL70i are interesting monitors. They are 17" but take less desktop space than most 15" monitors. The GS771-2 is only 15.2" deep and weighs 35 lbs.

All of the 15" monitors are really only useful at 1024x768 where they all do 72Hz or better refresh rates. The PM15 and 15GA-2 offer a very good screen quality and built in speaker/MIC combination for multimedia use. They aren't great speakers, but they are good enough and keep the clutter off the desktop. All of these units offer a 3yr warranty.

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