Filter
Top Products
FAQs (Frequently Asked Questions)
A: An LCD is made with either a passive matrix or an active matrix display grid. An active matrix has a transistor located
at each pixel intersection, requiring less current to control the luminance of a pixel. For this reason, the current in an
active matrix display can be switched on and off more frequently, improving the screen refresh time (your mouse pointer
will appear to move more smoothly across the screen, for example). The passive matrix LCD has a grid of conductors
with pixels located at each intersection in the grid.
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 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?
file:///C|/Documents and Settings/effie.chen//Philips/ENGLISH/190EW8/safety/saf_faq.htm (6 of 7)96/6/5 04:25:09