TFT Concept Analysis And Process Introduction

TFT (Thin Film Transistor) is short for thin film transistor. TFT display is the mainstream display equipment on all kinds of notebook computers and desktop computers, each LCD pixel on this kind of display is driven by the thin film transistor integrated behind the pixel, so TFT display is also a class of active matrix LCD display equipment. Is one of the best LCD color displays, TFT display with high responsiveness, high brightness, high contrast and other advantages, its display effect close to CRT display.

Each pixel of the TFT-LCD is controlled by the TFT integrated on itself, and they are active pixels. Therefore, not only the reaction time can be greatly accelerated, at least to about 80ms; Contrast and brightness are also greatly improved; At the same time, the resolution has been unprecedentedly improved. Because it has higher contrast and richer colors, the screen is updated faster, so we call it "true color".

Three main processes of TFT-LCD are introduced

Anterior segment
The first phase of the process is similar to the semiconductor process, but the difference is that the thin film transistor is made on glass, rather than silicon wafers.

midpiece
The middle section is based on the glass of the front section, combined with the glass substrate of the color filter, and the liquid crystal (LC) is injected between the two glass substrates.

Back end (module assembly)
The post-module assembly process is a production operation in which the glass after the Cell process is assembled with other components such as backlit plates, circuits, outer frames, and so on.

TFT type liquid crystal display is more complex, mainly composed of: fluorescent tube, light guide plate, polarizer, filter plate, glass substrate, direction film, liquid crystal material, thin mode transistor and so on. First, the LCD must first use a backlight, that is, a fluorescent lamp to project a light source, which will first pass through a polarizer and then through the liquid crystal. At this time, the arrangement of liquid crystal molecules will change the Angle of light through the liquid crystal, but these light must also pass through the front of the colored filter film and another polarizer. Therefore, as long as we change the voltage value of the stimulated liquid crystal, we can control the light intensity and color of the final appearance, so that we can change the color combination of different tones on the liquid crystal panel.

TF color filters are divided into red, green and blue according to color, which are arranged on the glass substrate to form a group (dot pitch) corresponding to a pixel. Each monochromatic filter is called a sub-pixel. In other words, if a TFT display supports a maximum resolution of 1280×1024, then at least 1280×3×1024 sub-pixels and transistors are required. For a 15-inch TFT display (1024 x 768), then a pixel is approximately 0.0188 inches (equivalent to 0.30mm), and for an 18.1-inch TFT display (1280 x 1024), it is 0.011 inches (equivalent to 0.28mm).

As we all know, pixels are decisive for the display, and the smaller each pixel, the larger the maximum resolution the display can achieve. However, due to the limitations of the physical characteristics of the transistor, the size of each pixel of the TFT is basically 0.0117 inches (0.297mm), so for a 15-inch display, the maximum resolution is only 1280×1024.