STN Technology

Description for STN Display

STN liquid crystal (Super-twisted nematic display) is the abbreviation of super twisted nematic liquid crystal. After TN liquid crystal was invented, people naturally thought of matrix TN liquid crystal to display complex graphics. Relative to the TN liquid crystal twists 90 degrees, the STN liquid crystal twists 180 degrees to 270 degrees. Color STN liquid crystal came out in the early 1990s. One pixel of this liquid crystal is composed of three liquid crystal cells, covered with a layer of the color filter, and the brightness of the liquid crystal cells is controlled by the voltage to produce colors.

STN liquid crystal is composed of TN liquid crystal units with fast reaction speed, but the liquid crystal particles are large, scanning speed and brightness are not as good as the TFT liquid crystal that appeared later. Due to low prices, hand-held mobile phones, video game consoles, and laptops produced before 2000 are widely used as STN main displays. Now has basically withdrawn from the consumer market.

STN liquid crystal has yellow, green and black characters, and blue and white characters, the pursuit of contrast using the former, emphasis on brightness occasions using the latter."

Description for FSTN Display

FSTN-Film Compensated STN, film-coated STN, insert a layer of polymer film into the STN, can only display monochromatic, used in word processors and portable electronic devices. [2] 

CSTN-Color Super-Twist Nematic, color STN, the earliest color LCD, mainly for mobile phones and portable game consoles (e.g. Game Boy Color).

DSTN-Dual-scan Super Twisted Nematic, double scan STN, STN liquid crystal is divided into two parts, which is to speed up the scanning speed to eliminate the image. Used on early laptops.

DSTN-Double-layer Super Twisted Nematic, double STN.

Description for TN Display

Twisted nematic liquid crystal (TN, twisted nematic liquid crystal) is the most common liquid crystal driving mode.

The two polarizers P1 and P2 are placed in parallel at 90 degrees. The liquid crystal LC is injected between the polarizer P1, P2(in fact, the polarizer and liquid crystal are separated by glass layer G and conductive plate E1, E2), and the liquid crystal molecules are arranged in a spiral shape when the polarizer is not electrified so that the light is gradually distorted through the polarizer. Under the condition of electrification, the liquid crystal molecules will be arranged in the normal direction of the polarizer due to the action of the electric field. Because the two polarizers are in the direction of 90 degrees, the light can not pass through the polarizer.

TN liquid crystal has been widely used since the invention of liquid crystal technology until VA、IPS liquid crystal appeared. TN liquid crystals dominate the display market of calculators, computers and general electronic devices, and now TN liquid crystals have been phased out. TN liquid crystals have the following characteristics:

Advantages of STN Technology

  • Low cost.

  • Without electrification, the luminous efficiency is high. achieving the same brightness is more power-saving than other ways. So it is widely used in low-cost portable electronic devices.

  • The response speed is fast, only this kind of technology can deal with when needing a high-speed display.

Disadvantages of STN Technology

  • The visual angle is narrow. From the left and right up and down the brightness significantly darkened.

  • Color distortion. The color changes from left to right.

  • Color and contrast are not as good as VA、IPS.

Difference between TN and STN

Twisted Nematic (TN) and Super Twisted Nematic (STN) are the terms used to describe two types of liquid crystal displays. TN displays have a twist ( the rotation of the molecules from one plane of the display to the other) of 90 degrees or less. All passive direct drive , active matrix, and most passive low level (x2 to x32) multiplexed LCD's have a 90 degree twist.

As the name implies, Super Twisted Nematic LCD's have a twist that is greater than 90 but less than 360 degrees. Currently most STN displays are made with a twist between 180 and 240 degrees. The higher twist angles cause steeper threshold curves which put the on and off voltages closer together. The steeper thresholds allow multiplex rates greater than 32 to be achieved.