Common LIQUID crystal displays are divided into four types:

1.(Twisted Nematic-LCD)

2. Stn-lcd (Super TN-LCD, Super twisted nematic LCD)

3. Dstn-lcd (Double layer STN-LCD, Double layer super-twisted nematic LCD)

Tft-lcd (Thin Film Transistor LCD)

Tn-lcd and STN-LCD seem to differ little from each other structurally, but in essence their working principles are completely different:

(1) The distortion Angle in the TN liquid crystal box is 90°; In the STN liquid crystal box, the distortion Angle is 270° or nearby.

② In the TN liquid crystal cell, the polarizing axis of the polarizing mirror is parallel to the long axis of the liquid crystal molecule on the upper substrate surface, and the polarizing axis of the polarizing mirror is parallel to the long axis of the liquid crystal molecule on the lower substrate surface, that is, the upper and lower polarizing axes are 90° to each other; In the STN liquid crystal cell, the upper and lower polarizations and the upper and lower long axis of the substrate molecules are not parallel to each other, but into an Angle, generally 30°.

TN liquid crystal box is the use of liquid crystal molecular optical rotation characteristics, and STN liquid crystal box due to the polarizing light and liquid crystal molecules through the polarizing mirror Angle, so that the incident light is decomposed into normal beam and abnormal beam two kinds, through the liquid crystal box two light path difference, interference occurs when passing through the polarizing mirror. So STN liquid crystal box is the use of liquid crystal birefringence characteristics of work.

TN liquid crystal box works in black and white mode; STN liquid crystal box generally works in the case of optical path difference of 0.8μm, interference color is yellow. When the voltage is greater than Vth, the white light can pass through the liquid crystal layer, but it is obviously weakened when passing through the polarization mirror. The liquid crystal box has a black appearance, called black/yellow mode. If the optical axis of the polarizer rotates 30° to the left of the long axis of the liquid crystal molecule on the side of the emerging light, it is white/blue mode. That is, without voltage, the liquid crystal box is blue; When the voltage is increased, the LIQUID crystal box has a colorless appearance. So STN is colored mode.