Liquid Crystal Displays that work without power

What is it about?

Complex LCD panels use a thin-film transistor (TFT) behind every pixel to ensure that the correct signals are applied to the millions of picture elements. Before this was feasible, bistable LCD offered a route to simpler high complexity displays. Bistability means that the black and white states are retained without power, meaning that each display could be addressed line by line to build up an image but without the TFT. Today, with TFT being cheap and reliable, bistable displays are used instead for displays where power is precious, since they can retain the image even when power is discontinued.This is a review article that explains the key developments, and the drivers behind them. Particular emphasis is made on Ferroelectric Liquid Crystals, Bistable Nematics and Cholesterics.

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Why is it important?

These types of device continue to have promise for non-display applications, as optical elements, switchable lenses, etc.