FAQs (Frequently Asked Questions)
LCD Panel Technology
Q:
What is a Liquid Crystal Display?
A:
A Liquid Crystal Display (LCD) is an optical device that is commonly used to display ASCII
characters and images on digital items such as watches, calculators, portable game consoles, etc.
LCD is the technology used for displays in notebooks and other small computers. Like light-emitting
diode and gas-plasma technologies, LCD allows displays to be much thinner than cathode ray tube
(CRT) technology. LCD consumes much less power than LED and gas-displays because it works on
the principle of blocking light rather than emitting it.
Q:
How are LCDs made?
A:
LCDs are created from two glass plates separated from each other at a distance of a few
microns. The plates are filled with liquid crystal and then sealed together. The top plate is colored
with an RGB pattern to make the color filter. Polarizers are then glued to both plates. This
combination is sometimes called 'glass' or 'cell.' The LCD cell is assembled into a 'module' by
adding the backlight, driver electronics and frame.
Q:
What is polarization ?
A:
Polarization is basically directing light to shine in one direction. Light is electromagnetic waves.
Electric and magnetic fields oscillate in a direction perpendicular to the propagation of the light
beam. The direction of these fields is called the 'polarization direction'. Normal or non-polarized light
has fields in several directions; polarized light has a field in only one direction.
Q:
What differentiates passive matrix LCDs from active matrix LCDs?
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:
How does a TFT LCD Panel work?
A:
On each column and row of the TFT LCD panel, a data source drive and a gate drive are attached,
respectively. The TFT drain of each cell is connected to the electrode. The molecular arrangement of
liquid crystal elements differ according to whether it is impressed with voltage or not. It varies the
direction of polarized light and the amount of light by letting it through different arrays of liquid
file:///D|/My%20documents/dfu/150V5/english/150v5/safety/saf_faq.htm (4 of 6) [4/14/2004 11:08:58 AM]
