Theory of the Processing Unit and display unit
IN the Processing unit we have used AT 89c52 microcontroller which has done the whole thing actually, like controlling the display unit by LCD,module and optopcoupler.There are three basic module 89c51,display unit and sensor mode. When car or any vehicles is moving the speed is recorded and displaying by the LCD.the microcontroller is connected it with all required connectionís IC 4n35 is connected to the microcontroller. The IC 4N35 is a 6 pin IC.The Pin no 6 is connected to the sensor port. This is record the speed of vechile.one data segment is connected to the LCD.which helps us to display the speed digitally
Theory of the Display Unit:
A liquid crystal display (LCD) is a thin, flat electronic visual display that uses the light modulating properties of liquid crystals (LCs). LCs do not emit light directly.They are used in a wide range of applications, including computer monitors, television, instrument panels, aircraft cockpit displays, signage, etc. They are common in consumer devices such as video players, gaming devices, clocks, watches,calculators, and telephones. LCDs have displaced cathode ray tube (CRT) displays in most applications. They are usually more compact, lightweight, portable, less expensive, more reliable, and easier on the eyes. They are available in a wider range of screen sizes than CRT and plasma displays, and since they do not use phosphors, they cannot suffer image burn-in.LCDs are more energy efficient and offer safer disposal than CRTs. Its low electrical power consumption enables it to be used in battery-powered electronic equipment. It is an electronically-modulated optical device made up of any number ofpixels filled with liquid crystals and arrayed in front of a light source (backlight) or reflector to produce images in colour ormonochrome. The earliest discovery leading to the development of LCD technology, the discovery of liquid crystals, dates from 1888. By 2008, worldwide sales of televisions with LCD screens had surpassed the sale of CRT units. Here we are using this for only the display of speed.