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# TFT LCD

Thin film transistor liquid crystal displays (TFT LCD) are the type of flat panel display technology used in personal computers, televisions and many mobile devices. Reason why TFT LCD are so popular is because they offer superior reliability with low cost price (Jungho Jung, et al) as well as continuous improvements from the manufacturers. They are getting better at making the backplane film transistors, the liquid crystal modes and the system level efficiency of thin film transistor liquid crystal displays.

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## 1. Core component

#### 1.1. Backlight unit

Backlight unit is the light source behind the panel. It is made up of LEDs, optical films, light guides, and diffusion layers. The function is to provide uniform white light because the LCD pixels do not produce any light.

#### 1.2. Polarizers

LCD has two polarizing films, one on each side of the crystal cell. These films take the light from the backlight. Turn it into polarized light, then the liquid crystal cell layer either rotates or blocks this polarization to control how bright the screen is.

#### 1.3. TFT array on glass

TFT array is like a layer (active-matrix backplane) on the glass substrate. Each pixel or subpixel is connected to a thin-film transistor. This transistor drives the voltage that is needed to set the orientation of the liquid crystal.
#### 1.4. Liquid crystal layer

The liquid crystal layer sits between the two glass plates. It acts like a controllable optical shutter where it changes optical properties when voltage is applied.

#### 1.5. Color filter layer

Color filter layer is what divides the display into red, green, and blue subpixels. Each subpixel only lets one color through so the panel can make full color images.

#### 1.6. Driver circuits

Driver circuits include row and colomn drivers, timing control, and often source/gate driver ICs. These circuits give the pixels the voltages and signals at the right time. This is how the LCD can show the images the user wants to see.