How can an LCD create images from a grid of pixels?
In nematic arrangements the crystals are randomly positioned with all their long axes pointing in essentially the same direction, given by a vector known as the director. In smectic arrangements the crystals are further constrained to parallel planes; in smectic A the director is perpendicular to these planes, while in smectic C the director is at some other angle to the planes.
A liquid crystal display (LCD) creates images by manipulating the optical properties of liquid crystal layers using an electric field.12
At the core of this process is the electro-optical effect: applying a small voltage changes the orientation of liquid crystal molecules, which alters how they interact with light. In a common twisted-nematic cell, the liquid crystal rotates the polarization of light, allowing it to pass through crossed polarizers. When an electric field is applied, the molecules realign, losing their ability to rotate the light's polarization, which causes that specific area to appear dark.23
By arranging these assemblies into a grid, an LCD can display images by selectively turning individual points on or off. For high-resolution displays, thin-film transistor (TFT) technology is used, where each pixel is controlled by its own transistor switch. Color images are achieved by grouping pixels with red, blue, and green filters, while a backlight provides the necessary illumination for the display.34