How the display is driven


Both liquid crystal display or OLED display are divided into two categories: active display and passive display. For LCD display, it is divided into passive (passive) drive display LCD, such as Color-STN-LCD display, STN-LCD, TN-LCD, etc.; active (active) drive display LCD, such as TFT-LCD. Display OLED (AMOLED).


Passive (passive) drive display OLED or LCD usually can only display less than 200 lines at the same time, so to display more lines to achieve high definition, active (active) drive display method, i.e., TFT-LCD, AMOLED.


TFT thin-film technology

Polysilicon thin film


Polysilicon thin-film processes fall into two main categories.


(1) High-temperature process, refers to the entire process of the temperature is higher than 900 ℃. The high-temperature process can only expensive quartz as a substrate, TFT performance is good, the high-temperature process is only applicable to small and medium-sized display or projection screen series.


(2) low-temperature process, the temperature during the whole process is lower than 600 ℃. The low-temperature process can be made on the cheap glass substrate larger display. Low-temperature polysilicon (LTPS) TFT is a widely used inactive (active) drive display TFT-LCD and AMOLED due to its low power consumption, lightweight, thinness, providing high current and system integration. The key to the process of polysilicon TFTs is how to prepare excellent polysilicon films cost-effectively and over large areas. At present, the preparation of polysilicon material methods are rapid annealing (RTA), excimer laser crystallization (ELC), solid-phase crystallization (SPC), continuous lateral crystallization (SLS) and metal-induced low-temperature polysilicon (MIC) technology, and so on.


Low-temperature polysilicon LTPS TFT technology can completely solve the problems that amorphous silicon TFT technology cannot solve. Especially after 2000, due to the overcapacity of a-Si TFT, Japanese, Korean and Taiwanese manufacturers actively invested in LTPS TFT, so that LTPS TFT has more development opportunities in the next few years. LTPS TFT has been regarded as the necessary technology for the next generation LCD for a long time.


Organic film TFT


The emergence of organic TFT will form a strong competition to the existing amorphous silicon TFT is self-evident. It will be a new generation of flexible display of the core technology, the use of flexible display technology to create a display can be curled like a canvas, and may become an important part of the future display world like an LCD.


Due to the use of organic materials, which feature a bendable display, it is not only impact-resistant but also lightweight and compact. This not only changes the appearance of the display but also expands and diversifies the application environment. The tape and reel process, which is similar to the newspaper printing process, is used to print the display on a plastic film sheet, which greatly reduces production costs.

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TFT technology and its development