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Philips 190C1SB-00 User Manual

Page 9

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FAQs (Frequently Asked Questions)

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Q:

What are the advantages of TFT LCD compared with CRT?

A:

In a CRT monitor, a gun shoots electrons and general light by colliding polarized

electrons on fluorescent glass. Therefore, CRT monitors basically operate with an

analog RGB signal. A TFT LCD monitor is a device that displays an input image by

operating a liquid crystal panel. The TFT has a fundamentally different structure than

a CRT: Each cell has an active matrix structure and independent active elements. A

TFT LCD has two glass panels and the space between them is filled with liquid

crystal. When each cell is connected with electrodes and impressed with voltage, the

molecular structure of the liquid crystal is altered and controls the amount of inlet

lighting to display images. A TFT LCD has several advantages over a CRT, since it

can be very thin and no flickering occurs because it does not use the scanning
method.

Q:

Why is vertical frequency of 60Hz optimal for an LCD monitor?

A:

Unlike a CRT monitor, the TFT LCD panel has a fixed resolution. For example, an

XGA monitor has 1024x3 (R, G, B) x 768 pixels and a higher resolution may not be

available without additional software processing. The panel is designed to optimize

the display for a 65MHz dot clock, one of the standards for XGA displays. Since the

vertical/horizontal frequency for this dot clock is 60Hz/48kHz, the optimum frequency
for this monitor is 60Hz.

Q:

What kind of wide-angle technology is available? How does it work?

A:

The TFT LCD panel is an element that controls/displays the inlet of a backlight

using the dual-refraction of a liquid crystal. Using the property that the projection of

inlet light refracts toward the major axis of the liquid element, it controls the direction

of inlet light and displays it. Since the refraction ratio of inlet light on liquid crystal

varies with the inlet angle of the light, the viewing angle of a TFT is much narrower

than that of a CRT. Usually, the viewing angle refers to the point where the contrast

ration is 10. Many ways to widen the viewing angle are currently being developed and

the most common approach is to use a wide viewing angle film, which widens the

viewing angle by varying the refraction ratio. IPS (In Plane Switching) or MVA (Multi

Vertical Aligned) is also used to give a wider viewing angle.

Q:

Why is there no flicker on an LCD Monitor?

A:

Technically speaking, LCDs do flicker, but the cause of the phenomenon is

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