Polymeric Sensors and Actuators

Chapter 16

Liquid Crystal Displays

Commonly, an actuator is understood in the mechanical sense, e.g., as a micromechanical device that changes its dimensions on demand. In some extended content, a liquid crystal display can be understood as a device that changes its optical properties and allows in this way some wavelengths to pass and others to filter off.

In fact, an electric field will induce a geometric orientation of the liquid crystalline medium so that the term actuator is also justified in some mechanical way on a molecular base. The basic issues of liquid crystal displays are the subject of several monographs (1,2).

A liquid crystal display device is widely used as a monitor of a personal computer or a portable device and for television applications. It has various advantages such as low voltage, low power consumption and feasibility of thickness reduction, size reduction and screen size enlargement (3).

16.1 Basic Design

The schematic design of a modern liquid crystal display device is shown in Figure 16.1. The the upper polymer substrates retain the liquid crystal layer and are formed of a sheets with sufficient mechanical strength. Examples for these sheet materials include glass or silicon and a polymer film, such as poly(ethylene terephthalate) (PET), poly(ethylene naphthalate), poly(carbonate) poly(sulfone), or a poly(ether sulfone). Of course, the sheets must be transparent to incident light, otherwise no image can be formed. The thickness of substrate is from 25 ...