Laptop Monitors
LCD's are common because they offer some real advantages over other display technologies. They are thinner and lighter and draw much less power than cathode ray tubes (CRTs), for example. The simplest LCD is found in most calculators. When using LCD for computer displays they take the technology a step further and add color.
LCD's use a simple grid to supply the charge to a particular pixel on the display. Creating the grid is quite a process! It starts with two glass layers called substrates. One substrate is given columns and the other is given rows made from a transparent conductive material. The rows or columns are connected to integrated circuits (ICs) that control when a charge is sent down a particular column or row. The liquid crystal material is sandwiched between the two glass substrates, and a polarizing film is added to the outer side of each substrate.
To turn on a pixel, the integrated circuit sends a charge down the correct column of one substrate and a ground activated on the correct row of the other. The row and column intersect at the designated pixel and that delivers the voltage to untwist the liquid crystals at that pixel. This is how the image is made on the screen. Because we are only sending data through these IC's, very little energy is used in the process, which makes LCD technology energy efficient.
An LCD that can show colors must have three subpixels with red, green and blue color filters to create each color pixel. Through the careful control and variation of the voltage applied, the intensity of each subpixel can range over 256 shades. Combining the subpixels produces a possible palette of 16.8 million colors. LCD technology is constantly evolving. LCD's today employ several variations of liquid crystal technology. Manufacturers of existing large LCD's often reject about 40 percent of the panels that come off the assembly line. The level of rejection increases the price of this type of technology. This is why we don't have big-screen LCD TVs hanging on our walls: Only advances in manufacturing can lead to affordable displays in bigger sizes.