LED display development 30 years back

The 1970s the earliest GaP, GaAsP homogeneous "red, yellow, and green low the luminous efficiency LED lamp, has been used in digital and text display. Since then LED began to enter into the many applications areas, including aerospace, airplanes, cars, industrial application, communications, consumer products, across sectors of the national economy and homes. By 1996 in the world turnover has LED the billions of dollars. Although many years since LED is always color and luminance, but due to the restricted GaP and GaAsP LED have long life, high reliability, working current is small, but with TTL, CMOS digital circuit compatible and many other advantages and has been attained renown by users. In recent years, high brightness change, change is always full-color LED devices and materials technology the forefront of research topic. Brightness (UHB) refers to meet or exceed the luminous intensity 100mcd LED, also called high-security (CD) class LED. High brightness LED A1GaInP and the development of InGaN progress very rapidly, have now reached conventional materials GaA1As, GaAsP, GaP cannot reach a performance level. 1991 Toshiba and the United States InGaA1P 620nm developed by HP company brightness LED, orange, yellow InGaA1p590nm 1992 high brightness LED practional utilization. That same year, Toshiba InGaA1P 573nm yellow-green developed high brightness LED to light intensity, method of 2cd. In 1994, the company developed in Japan InGaN 450nm blue (green) color brightness LED. So far, the color display needed three colors red, green, blue and orange, yellow multiple color leds have reached the luminous intensity high-security level, realized the high brightness, full-color melt, the outdoor full-color display luminous tubes become a reality. China's development started in the 1970s LED appears in the 1980s, industry. The national about more than 100 enterprises, 95 percent of the manufacturer engaged in production, that after encapsulation almost all required tube core imported from abroad. Through several "five-year plan" technical reformation, technical research, introduce the foreign advanced equipment and some key technology, make our country LED production technology has a weltburgergesellschaft step forward.

Second, the high brightness LED performance:
��ultra-high brightness red A1GaAsLED and GaAsP-GaP LED compared with a higher luminous efficiency, transparency lining low (TS) A1GaAs LED (640nm) of the luminous efficiency is close to 10lm / w, than the red GaAsP-GaP LED Big 10 times. InGaAlP LED provides high brightness GaAsP-GaP LED color and the same are: green and yellow (560nm), greenish yellow (570nm), yellow (585nm), yellow (590nm), orange (605nm), light red (625nm deep red (640nm). A1GaInP LED luminous efficiency of a transparent substrate and the other LED and incandescent lighting structure comparison, InGaAlP LED absorbing substrate (AS) the lumen efficiency of 101m / w, a transparent substrate (TS) for the 201m / w, 590 -626nm wavelength range than GaAsP-GaP LED's luminous efficiency of 10-20 times higher; in the 560-570 range of wavelengths than GaAsP-GaP LED is 2-4 times higher. provides high brightness blue InGaN LED shade and green light, the wavelength range of blue for the 450-480nm, blue green is 500nm, green is 520nm; its luminous efficiency 3-151m / w. high brightness LED luminous efficiency of the current with a filter over the incandescent lamps, can replace the incandescent power 1w or less, and the LED array can replace the power with less than 150w incandescent. For many applications are using filters to get the incandescent red, orange, green and blue, but with Ultra bright LED can be the same color. AlGaInP materials and InGaN materials in recent years, the high brightness LED manufacturing multiple (red, blue, green) combined with ultra-high brightness LED chips, can also be obtained without the filter colors. including red, orange, yellow, green, blue, and the luminous efficiency are currently more than incandescent, fluorescent positive close. brightness higher than the 1000mcd, can meet the outdoor all-weather, full-color display, with LED color big screen can show the sky and sea, to achieve three-dimensional animation. a new generat

Communication No. Instructions: replace incandescent lamps with a super bright LED for traffic lights, warning lights, marker lamps have been around the world, a vast market, demand is growing rapidly. According to the U.S. Department of Transportation statistics in 1994, the United States to install traffic lights at the crossroads of 26 million, each intersection must be at least 12 red, yellow, blue and green lights. There are many additional changes in crossing signs and crosswalk warning lights across the road. Thus, each intersection can have 20 lights, but to also light. Could be projected that the United States there are about 135 million traffic lights. Currently using high brightness LED lamps to replace the traditional incandescent reduce power consumption has achieved remarkable results. Japan's annual electricity consumption at the traffic lights on about 100 million kilowatts, to replace incandescent lamps with ultra-high brightness LED, its power consumption is only 12% of the original.
��traffic lights the competent authorities of each country must develop appropriate specifications, the color of the provisions of the signal, the lowest light intensity, spatial distribution of the beam pattern and the installation environment requirements. Although these requirements are written by incandescent lamps, but now with the high brightness LED traffic lights are basically applicable. LED traffic lights with incandescent compared to a longer working life, generally up to 10 years, taking into account the environmental impact of outdoor poor, life expectancy should be reduced to 5-6 years. The current high brightness AlGaInP red, orange, yellow LED has been achieved industry, the price is relatively cheap, if the composition of red high brightness LED modules to replace the traditional incandescent traffic signal head of red because red incandescent lamp can be a sudden failure of the Security low impact to a minimum. General LED traffic signal modules in series by a number of groups composed of LED single lamp to 12-inch red LED traffic signal modules, for example, in the 3-9 group of single series LED lamp, LED single lamp series each number is 70-75 months (a total of 210-675LED single lamp), when there is a single LED lamp failure will only affect a group of signals, the rest of the group has been shortened to 2 / 3 (67%) or 8 / 9 (89%) and not as incandescent lights, as the first failure of the whole.
��LED traffic signal module is the main problem is made still appears to be higher referred to the 12-inch TS-AlGaAs red LED traffic signal modules, for example, was first used in 1994, the cost is $ 350, but better performance in 1996 good 12 British AlGaInP LED traffic signal modules, the cost was $ 200. Expected in the future will not be long, InGaN blue and green LED traffic signal module prices will be compared with the AlGaInP. The cost of incandescent traffic signal head was low, but power consumption, a diameter of 12 inches the electricity consumption of incandescent traffic signal heads for the 150W, crossing traffic warning lights sidewalk power consumption 67W, it has been calculated for each intersection The annual power consumption of incandescent lights 18133KWh, equivalent to annual electricity for the 1450 $; but LED traffic signal module is very low power consumption, each 8-12 inch red LED traffic signal module power consumption of 15W, respectively, and 20W, crossroads LED sign can turn the arrow at the switch shows the power consumption is only 9w, it has been calculated annually for each intersection power 9916KWh, a considerable annual savings of $ 793 electricity bill. Each LED traffic signal module according to the average cost of $ 200 dollars, the red LED traffic signal modules only the savings in electricity, 3 years after the initial construction costs recovered, and began to get economic returns. Therefore, the current module using the AlGaInP LED traffic information, although the cost seems to, but long to see, or cost-effective.