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Monitor Maintenance - March 2009:
Monitors are an important, and widely ignored, component of the
PC. Often a vendor will toss whatever monitor he has lying
around in with your purchase, regardless of its quality, its
compatibility with your system, or your own needs and
preferences.
You
need to insist on the best monitor you can get for your dollar
(and better doesn't necessarily mean bigger). Color monitors
rely on color CRTs, which use three electron guns to fire three
streams of electrons in a beam that will hit a three-dot or
three-stripe pattern on the face (hence the terms dot pitch
and stripe pitch). Electromagnets force the electron
beams to sweep across the display one line of pixels
(picture elements) at a time. At the typical resolution of 1,024
by 768, for instance, each line contains 1,024 pixels, and there
are 768 lines which must be drawn each time by the electron
guns. The electron guns are one source of fuzzy displays; the
larger the screen, the more fuzzy the display at the edges of
the screen. Cyber types call this astigmatism, same as
what causes me to wear glasses with such thick lens edges. The
electrons hit the phosphor compound on the monitor display,
causing it to glow. The compound glows for varying periods of
time and in varying color patterns, giving you the picture that
you see on your monitor. Right now your monitor is showing you a
mostly white background with black letter-shaped squiggles. When
you get sick of this page and plug in Quake, your monitor
will work much harder to show you the beasties and backgrounds
of that program.
The
color CRT contains three different phosphor compounds: red,
green, and blue. Different colors are created by the electrons
striking the three compounds in different ways. The three
compounds are arranged on the screen in three-dot patterns (the
stripes consist of three lines of red, green, and blue). Each
three-dot, or three-stripe, pattern is called a pixel. The space
between dots of the same color is known as the dot pitch; with
stripes, it is called the stripe pitch. Monitors come in three
types: those using dots (shadow-mask, flat-square, or dot trio),
those using stripes (aperture-grille), and a cross between the
two (slot-mask). Sony Trinitrons are aperture-grill CRTs, and
NEC CromaClears are slot-masks, along with some Panasonics. Most
others, particularly the more affordable models, are
shadow-masks. Do you care? Not enough to make one type a
necessity. The cyber wonks will argue one type over another, but
the rest of us can't tell enough of a difference to make buying
one kind over another a sticking point when negotiating for a
good deal. (Note: a few users find the horizontal wires used in
an aperture-grill CRT both visible and annoying. Check one out
before you buy one, as you may be one of the discerning - or
picky - few.) You will also hear a lot of static about the dot
pitch, or DP, or the stripe pitch. Shadow-mask CRTs measure
their size in DP, while aperture-grille CRTs measure theirs in
SP. They cannot be directly compared. A rule of thumb is that an
SP CRT will have a slightly lower number than a comparable DP
CRT; for example, an 0.28mm DP is considered roughly equal to a
0.25mm SP CRT. Don't let the salesman blow smoke up you about
this one. A good monitor has a dot pitch of around 0.28mm, but a
slightly higher number isn't a reason to quit considering the
monitor. Dot pitch is only one consideration.
And
what the dickens is "refresh rate?" It is the rate that a
monitor redraws the screen (watch a video of a functioning
monitor to see the screen refreshing itself; thankfully it
doesn't look like that to the naked eye). A refresh rate of 85
Hz is virtually flicker-free to the most discerning eye, but a
rate as low as 72 Hz is perfectly acceptable for most of us.
(Most TVs have a refresh rate of about 30 Hz; no monitor has a
rate below 60 Hz.) And a too-high refresh rate can degrade image
quality. You can experiment with different refresh settings;
keep your eye just above or to the side of your screen, and
lower the refresh rate until any perceptible flicker you can
detect out of the corner of your eye is gone. How to change the
refresh rate? In most flavors of Windows, right-click the
desktop, choose Properties, Settings, and click on the advanced
button. Under the Adapter tab, you'll see a list of available
refresh rates. Choose the highest one that you can get away with
(you may have to experiment). In XP, go through Display
Properties and choose Settings, Advanced, Adapter, and List All
Modes.
Some
people find themselves with flickering monitors that induce
migraines; they go in to increase their refresh rate, but their
only option is 60 Hz. Not good. What's happened is that Windows
has lost track of the monitor's Plug and Play configuration, and
is using the 60 Hz default as a safety measure (since a too-high
refresh rate can damage the monitor). Fortunately, this is an
easy fix: just go back into the Properties, Settings, Advanced
menu as listed in the tip above, and choose Monitor. Check the
"Automatically detect Plug & Play monitors" box, and reboot. If
this doesn't work, you'll need to click the Change button and
reinstall the monitor. If this doesn't work, your monitor
may not be set to support anything higher than 60 Hz under the
current resolution rate; lower the screen resolution and recheck
the refresh rates to see if you're offered anything better.
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