Table of Contents
Advertisement
Principle of Liquid Crystal
On the contrary, in the condition (Switch-On) that voltage is supplied, the liquid crystal molecules are
arranged in a line at right angles to a glass plate. Since vertical liquid crystal molecules do not affect the
oscillating direction of light, the light that passed the upper polarized board passes as it is without chang-
ing the oscillating direction. Since the oscillating direction of this light differs from direction of the lower
polarized board which is shifted 90º and arranged, the light collides with this polarized board and cannot
pass. This is the liquid crystal shutter-off condition and the LCD panel (LCD shutter) blocks the light.
This is the basic structure (On—Off of the light by the LCD shutter) of an LCD panel. It is a sandwich
structure of the upper and lower sides of transparent electrodes, alignment films, and polarized boards,
with an enclosed liquid crystal material between them.
The LCD panel shown in Fig. 10 is a type of panel that changes the light into a passage condition when
voltage is not supplied between the upper-and-lower polarized boards that are arranged at 90º. This type
of panel has the advantage that black contrast is improved, and it usually works well. This mode is called
"Normally White Mode."
An LCD panel that passes light when voltage is not supplied is referred to as "Normally Black Mode." In
practice, with this type (when the upper-and-lower polarized boards are arranged in the same direction),
displaying perfect black becomes difficult due to the leakage of light caused by variations in the arrange-
ment of the liquid crystal molecules.
Polarized
Board
Transparent
Electrode
(Upper)
Alignment
Film
Liquid
Crystal
Alignment
Film
Transparent
Electrode
(Lower)
Polarized
Board
3-4 Transparent Electrode
In order to generate an electric field in liquid crystal, voltage is supplied to the upper-and-lower elec-
trodes. If metal is used for these electrodes, the light is interrupted by this metal and cannot pass into the
liquid crystal. Therefore, a transparent electrode that passes light is used for the electrode of the LCD
shutter.
Passage
Interception
-11-
Training Manual Principle of LCD
Polarized
Board
Transparent
Electrode
(Upper)
Alignment
Film
Liquid
Crystal
Alignment
Film
Transparent
Electrode
(Lower)
Polarized
Board
Fig. 10
Operation of
LCD Panel
Advertisement
Table of Contents
