How does an active-matrix LCD control individual 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.
An active-matrix liquid crystal display (LCD) controls individual pixels by utilizing a grid of thin-film transistors (TFTs) and capacitors that are plated transparently onto the surface of the display.1
In this configuration, each individual pixel is associated with its own silicon transistor, which functions as an electronic switch. By applying a varying electric voltage to specific portions of the liquid crystal layer, these transistors allow the display to precisely control the optical properties of each pixel, effectively turning them on or off to create complex images.231
This active-matrix approach provides a significant advantage over passive-matrix displays by allowing specific portions of the crystal to respond more rapidly. For color displays, the system typically groups three elements together, each equipped with a primary-color filter (red, blue, and green), to generate a full-color image.12