The development and application of LED
LED has a long developing story for nearly 30 years. In the 1970s,GaP,GaAsP that produce yellow light,green light has been firstly used in indicator,digital and words display. From at that time,LED has been widely applied in many other fields wchich almost cover allthe deparments of national economy and every family,mainly including airline,bus,c industrial application,telecommunication,and consumption or something and so on.the turnover of LED has reached several billion dollars all over the world by 1996.LED has been restricted by the color and efficiency of light-emitting for many years,but it has beening accepted owing to GaP and GaAsPLED has the advantages of long life span,high reliability,low power consumption and compitiable to TTL,CMOS and any other digital circuit board.
In the recent 10 years,ultra high brightness(UHB),full color has been the top topic of the development of LED’s material and techniques.UHB means the CD of LED surpass 100mcd,which also called CD LED.the development and research of AlGaInp and InGaNLED has been developing rapidly,by now it reached a high level that other general GaAlAs,GaAsP,Gap can't.1991,a japanese company a HP successfully developed InGaAlp620nm that produce extra high brightness,1992,InGaAIP590nm that produce yellow ultra high brightness and been putted into practice.In the same year,Nira developed InGaAlP573nm that can display yellow and green ultra high brightness and the cd can reach to 2cd,1994,Nira wonderfully developed InGaN450nm that display blue and green ultra high brighness.therefore,the three basic colors(red,green,blue)needed to produce full color have reached a level of CD,making ultra high brightness,full color display a reality.
Traditional LED road traffic signal lamp engendered fall into abeyance probability accrete because of LED quantity too much.It is a big improvement over tungsten type road traffic signal lamps, but cost is high, and servicing inconvenient, the metropolitan municipal traffic technical improvement engineering annoyed all the time.
If it has a species LED bulb it needn't renewal the old bulb' shell, the LED quantity less than primary bulb, with lower failure rate, maintenance convenience, less cost of construction.
