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CompTIA A+ Certification All-in-One Exam Guide

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Figure 17-16 Narrow versus wide viewing angles

Try This! Test the Viewing Angle of LCDs

Take a trip to your local computer store to look at LCD displays. Don’t get

distracted looking at all the latest graphics cards, CPUs, motherboards,

and RAM—well, actually, it’s okay to look at those things. Just don’t

forget to look at monitors!

Stand about two feet in front of an LCD display. Look directly at the

image on the screen and consider the image quality, screen brightness, and

color. Take a small step to your right. Compare the image you see now to

the image you saw previously. Continue taking small steps to the right

until you are no longer able to discern the image on the display. You’ve

reached the edge of the viewing angle for that LCD.

Do this test with a few different monitors. Do smaller LCDs, such as

20-inch displays, have smaller viewing angles? Do larger displays have

better viewing angles? You might also want to test the vertical viewing

angles of some monitors. Try to find a monitor that is on your eye level;

then look at it from above and below—does it have a large viewing range

vertically? There’s also a curved LCD monitor variant not discussed in

this chapter, but worth looking at. What kind of viewing angle do they

have?

Response Rate An LCD panel’s response rate is the amount of time it takes

for all of the sub-pixels on the panel to change from one state to another.

Manufacturers measure LCD response rates in milliseconds (ms), with lower

BEING BETTER. There are two ways manufacturers measure this change. One is

black-to-white (BtW): how long it takes the pixels to go from pure black to

pure white and back again. The other is gray-to-gray (GtG): how long it takes

the pixels to go from one gray state to another.

The GtG time will always be faster than the BtW time. A typical modern

LCD has an advertised response rate of around 5 ms. The manufacturer will

almost always advertise the GtG response time. I found an LG display that

listed both times: 5-ms GtG and 14-ms BtW. You might find older displays

in use with BtW response times over 20 ms—this is slow enough that you

might notice image smearing if you try to watch a movie or play a fast-paced

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