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Improvement Technology of LCD Display
6-5 IPS (In-Plain Switching) System
The structure of an IPS system is shown in Fig. 25. The pixel and common electrodes are mounted to
the transparent film (drive transistor) side and the electric field is generated horizontally to the glass
plate. With this electric field, the alignment direction of liquid crystal molecules is rotated 90º in parallel to
the glass plate.
In the IPS system, liquid crystal molecules rotate all at once in the horizontal direction. Since these liquid
crystal molecules do not lean like the TN type, there is little change in the picture characteristics (con-
trast, brightness, hue, etc.) and the angle of view becomes wider. However, there are a few problems.
The quantity of transparent light is reduced, slower response speed, and a white picture becomes a little
bluish or yellowish depending on the viewing direction. The S-IPS (Super-IPS) type was developed to
improve upon these problems. In the S-IPS type, the structure of the electrode for driving the liquid crys-
tal molecules becomes a zigzag form, which reduces the change of color, increases the viewing angle to
about 160º and has high definition equivalent to a CRT.
Polarized
Board
Transparent Electrode
(Pixel)
Liquid Crystal Molecule
(Vertical)
Dark (Switch Off)
Basic Structure of IPS System
Electric
Field
Normally Black Mode
-25-
Glass Plate
(Without Transparent Electrode)
Alignment Film
Alignment Film
Transparent Electrode
(Common)
Glass Plate
Polarized
Board
Bright (Switch On)
Fig. 25
IPS (In-Plain Switching) System
Training Manual Principle of LCD
Polarized
Board
Alignment Film
Liquid Crystal
Molecule
(Vertical)
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