Philips 220V User Manual page 8

FAQs (Frequently Asked Questions)
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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?
Unlike a CRT monitor, the TFT LCD panel has a fixed resolution. For example, an XGA monitor has
A:
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?
The TFT LCD panel is an element that controls/displays the inlet of a backlight using the dual-refraction
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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 CDT. 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?
Technically speaking, LCDs do flicker, but the cause of the phenomenon is different from that of a CRT
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monitor -- and it has no impact of the ease of viewing. Flickering in an LCD monitor relates to usually
undetectable luminance caused by the difference between positive and negative voltage. On the other hand,
CRT flickering that can irritate the human eye occurs when the on/off action of the fluorescent object
becomes visible. Since the reaction speed of liquid crystal in an LCD panel is much slower, this troublesome
form of flickering is not present in an LCD display.
Q: Why is an LCD monitor virtually low of Electro Magnetic Interference?
Unlike a CRT, an LCD monitor does not have key parts that generate Electro Magnetic Interference,
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especially magnetic fields. Also, since an LCD display utilizes relatively low power, its power supply is
extremely quiet.
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