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Type of LCD Display Construction
Training Manual Principle of LCD
4 Type of LCD Display Construction
4-1 Twisted Nematic (TN) Type
A Nematic type of LCD Display where the liquid crystal molecules are twisted 90º between upper and
lower boards is called a Twisted Nematic type (TN type) liquid crystal.
Most LCD displays are of this type and feature high contrast (ratio) under low voltage and power.
4-2 Super TN (STN) Type
Super TN type (STN type) LCD Displays are used for LCD televisions, personal computer monitors, cel-
lular phones, etc. A liquid crystal material developed to improve visual characteristics, such as contrast
ratio is used.
In this STN type liquid crystal molecules are twisted 180º to 270º and arranged between upper and lower
electrodes. By supplying voltage to this liquid crystal, the transparent ratio of light changes more steeply.
Therefore, with the STN type as compared to the TN type, contrast and rise characteristic of the voltage
(response of switch On and Off) are improved, and a clearer picture on larger screens becomes possible.
4-3 Triple STN (TSTN) Type / Film STN (FSTN) Type
A fault of the STN type is that the display colors during On and Off of the LCD shutter become yellowish
green and navy blue. (In TN type, they are white and black.) This is because light of a specific wave-
length is reflected and scattered by the thickness of the LCD panel. Therefore, even if a color filter of
RGB is attached to an STN type liquid crystal, bluish green is mixed with the colors from black, gray to
white, and a natural color picture cannot be displayed. The triple STN type (TSTN type) and the film STN
type (FSTN type) have been developed as an advanced type of STN.
In the TSTN type, optically compensated films (high polymer films) which sandwich the upper and lower
LCD panels are used. They compensate for the twist of the light crystal cell, and the display colors of yel-
lowish green and navy blue are changed to the correct white and black. The "FSTN" type uses a single
optically compensated film
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