| The display is an important interface for the communication between human beings and machines. At early stage, Cathode Ray Tube (CRT) display took the lead. With the development of science and technology, in recent years, Liquid Crystal Display (LCD) gradually replaces CRT display as the mainstream, for it has such advantages as lightweight, thin, small, low power consumption, radiationless, plan rectangular display, steady image without scintillation, continuous falling price and etc. As a kind of low consumed power display device, LCD is applied widely to calculators, digital instruments, industrial monitored control systems and other low consumed power systems. As the most important display tool with most potential for the 21st century, the age of digital information, LCD will be applied to more and more fields, without doubt. So, combined with years work experience of my own, and based on the operating principle of LCD, this paper starts with the practical application and mainly studies various dot matrix LCD as well as their drive technique. Here a type of LCD with excellent cost performance, EDM12864 is presented. Along with just right application experience, quite good results are obtained. And all these could provide reference assistance for other types of LCD.The display principle of LCD is to place liquid crystal between two electro-conductive glass plates; and twist the liquid crystal molecules with the drive of the electric field between two electric poles, in order to control the transmission or shadow function of light source; between the power is turned on and off, light and shade are created and image is displayed; when color filter is added, color image could be displayed. According to the operating principle of LCD, and in order to solve the problems in its practical applications, I made lots of research efforts, listed as follows:A type of LCD with excellent cost performance, EDM 12864 ispresented. In an automatic industrial monitored control system, many functions have to be displayed, and the work environment is very complex. Dither character, disordered display screen and other phenomenon will appear on the dot matrix LCD with poor electromagnetic compatibility. And the LCD with good cost performance is always expensive and complex to operate. The LCD EDM12864 is manufactured with the full set of advanced liquid crystal display screen and liquid crystal display mould train manufacturing facility and technology introduced from USA. It is made with SMT.COB.TAB.COG mould train technology. It has quite good noiseproof feature and is very easy to operate.As to the software, good drivers for character display and Chinese-character display are provided. The program is written with assembly language and is run on the chip microcomputer MCS-51. The interface is very simple, just input the location of the character (or Chinese character) to be displayed on the LCD, and then input the initial address of the character (or Chinese character) character-mould offset. Modular design is adopted for the whole procedure. The complicated operations are completed by various subroutines. What the user has to know is the interface. The run time of the program is cut short and the reliability of the display system is increased. The control of start-power-end, clear screen with software, time delay and other effective methods to solve the practical problems are also discussed in the paper.As we know, the computer processes the information of 0 & 1 code string. Then how does the computer process the literal information? This relates to the problem how to express the characters with 0 & 1 code string, which is the problem of the "character mould" design. At the early stage of my research work, the character mould program was written with C language. See the relevant parts of the paper for details.Practices tell that only good LCD with good driver is far from enough. Good hardware electric circuit is required, too. First of all is the selection of power supply. By tests I choose the power...
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