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TFT – Thin Film Transistor


A TFT display is a form of Liquid Crystal Display with thin film transistors for controlling the image formation. The technology works by controlling brightness in red, green and blue sub-pixels through transistors for each pixel on the screen.The liquid-crystal behaviour is similar to that of a TN display, relying on 90-degree twisted stacks acting as a waveguide to control the passage of light through the display.

ITO electrodes are deposited on the upper and lower glass substrates, and red, green and blue colour filters are deposited on the inner surface of the upper substrate. A thin-film transistor is embedded in every sub-pixel, and connected to the data bus line.

This enables the display drive system to address every sub-pixel individually. By controlling the intensity of light transmitted through each colour filter, the TFT-LCD can display millions of colours. A storage capacitor is also embedded in each pixel to maintain an applied voltage across the cell during pixel updating.

When a signal is applied to the pixel, the liquid crystal changes from its twisted state to align with the electric field and prevent light passing through – much the same as in a TN display. The TFT-LCD is able to switch rapidly between ON and OFF states, allowing response times fast enough to support rapid display-update rates suitable for presenting video content or smooth animation.

TFT Structure

TFT Display

An LCD display that uses thin film transitor technology to improve contrast.