Liquid crystal matrix displays

Liquid crystal cells possess many properties that make their use in flat-panel displays very attractive. Most important, liquid crystal cells do not generate light but rather modify incident light, and they consume only a small amount of electrical energy while activated. The various electrical and optical properties of liquid crystal cells which make them useful for displays are reviewed in some detail. Several methods for speeding up the dynamic response of the cells are presented. The description of a variety of addressing schemes for activating liquid crystal cells in two-dimensional matrix displays is given. A number of these schemes have been tested in conjunction with a 2 × 18 element display matrix where the electrical environment of a full-size TV display has been faithfully simulated. The merits of both ac and dc excitation of cells in liquid crystal displays are discussed from the standpoint of complexity of addressing circuitry and operating life, as well as power consumption of the displays.