Technical Blog

Concept and Process Analysis of TFT-LCD

TFT (Thin Film Transistor) LCD is one of the active matrix liquid crystal displays (AM-LCD). It is suitable for large animation display because of its fast reaction time and good display quality. It is widely used in notebook computers, desktop computer displays, LCD televisions, LCD projectors and various large electronic displays.

TFT LCD is more complex, mainly composed of fluorescent tube, light guide plate, polarizer, filter board, glass substrate, alignment film, liquid crystal material, thin mode transistor, etc. First of all, LCD must use the backlight, that is, fluorescent tube to project the light source, which will pass through a polarizer before passing through the liquid crystal. At this time, the arrangement of liquid crystal molecules will change the angle of light passing through the liquid crystal, and then these light must pass through the front color filter and another polarizer. Therefore, we can control the light intensity and color of the final appearance only by changing the voltage of stimulating the liquid crystal, so that we can change the color combination of different tones on the liquid crystal panel.

Each pixel of TFT-LCD is controlled by TFT integrated in itself. They are active pixels. Therefore, not only the reaction time can be greatly accelerated, at least up to 80 ms, but also the contrast and brightness can be greatly improved. At the same time, the resolution has also been improved unprecedentedly. Because it has higher contrast and richer colors, and the screen update frequency is faster, so we call it “true color”.


Three-stage Major Processing of TFT-LCD

Anterior segment
The former process is similar to the semiconductor process, but the difference is that thin film transistors are fabricated on glass rather than on silicon wafers.
Middle part
In the middle section, the glass substrate of the previous section is combined with the glass substrate of the color filter, and liquid crystal (LC) is injected between the two glass substrates.
Rear segment (module assembly)
The latter module assembly process is to assemble the glass after Cell process with other components such as backlight plate, circuit, outer frame and so on.



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