June 15, 1997
June 15, 1997
June 18, 1997
2.107.1 - 2.107.10
Computer Interface for Liquid Crystal Display (LCD)
M. Rabiee Eastern Kentucky University
Mono-Color Liquid Crystal Displays (LCD) are often used in portable instruments, calculators, and digital watches. Color LCD displays are used with Lap-Top computers and small color televisions. In this paper we will first explain the construction of LCD displays. Then, we will design and build a digital interface circuit to connect a LCD display to the computer. Finally, we will discuss how to write a program to drive a particular LCD display.
Liquid Crystal Displays (LCDs) use very low power. Therefore, they are often used in battery-powered instruments. LCDs however do not omit light. They simply change the reflection of available light. Liquid Crystal Displays are created by placing a thin (approximately 10 mm) layer of liquid crystal fluid between two glass plates. A transparent electrically conductive film is placed on the rear glass plate. Transparent sections of the conductive film in the shape of characters are coated on the front glass. Voltage is applied between the LCD segment and the backplane. This produces an electric field region under the segment. The electric field changes the transmission of the light through the region under the segment film.
There are two types of commonly available LCDs, the Dynamic Scattering, and the Field Effect. In the Dynamic scattering LCD Display type, the modules under the fields are scrambled. This produces light characters on a dark background. In the Field-Effect type, light is absorbed in the presence of an electric field. This produces dark character on a silver-gray background. Figure 1 illustrates the basic construction of a LCD display.
Figure 1 A Liquid Crystal Display
Rabiee, M. (1997, June), Computer Interface For Liquid Crystal Display (Lcd) Paper presented at 1997 Annual Conference, Milwaukee, Wisconsin. 10.18260/1-2--6459
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