Philips 150S4FG-74 - Manual (Page 34)

FAQs (Frequently Asked Questions)
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 CDT 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 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?
A: Technically speaking, LCDs do flicker, but the cause of the phenomenon is different from that of
CRT 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 free of Electro Magnetic Interference?
A: Unlike a CRT, an LCD monitor does not have key parts that generate Electro Magnetic
Interference, especially magnetic fields. Also, since an LCD display utilizes relatively low power, its
power supply is extremely quiet.
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