Philips 170B6 User Manual page 38

FAQs (Frequently Asked Questions)
Q:
How are LCDs made?
Q:
What is polarization ?
Q:
What differentiates passive matrix LCDs from active matrix LCDs?
Q:
How does a TFT LCD Panel work?
Q:
What are the advantages of TFT LCD compared with CRT?
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principle of blocking light rather than emitting it.
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.
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.
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.
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 crystal elements.
When two polarized filters are arranged vertically on a polarized light pole, the light
that passes through the upper polarized panel is turned 90 degrees along with the
spiral structure of the liquid crystal molecules and goes through the polarized filter at
the bottom. When impressed with voltage, liquid crystal molecules are arranged
vertically from the original spiral structure and the direction of the light is not turned
through 90 degrees. In this case, light that comes through the top polarized panel
may not go through the polarized panel at the bottom.