30 years of development of LED display

1970s the earliest GaP GaAsP homojunctions, red, yellow and green low luminous efficiency of LED has been applied to the indicator numbers and text. Since then, LED began to enter a variety of applications, including aerospace, aircraft, automotive, industrial applications, communications, consumer products, etc., throughout the national economy and various sectors of the household. By 1996, LED sales in the world have reached billions of dollars.

Over the years LED has been subject to the limitations of color and luminous efficiency, but due to the GaP and GaAsP LED have long life, high reliability, low working current, with TTL and CMOS digital circuit compatible with many advantages such as it has been favored by the users. In recent ten years, high brightness, color is the topic of LED material and device technology research. Ultra high brightness (UHB) refers to the luminous intensity of LED or more than 100mcd, also known as Candela (CD) class LED. Progress in the development of high brightness A1GaInP and InGaN LED very quickly, the performance level has reached GaA1As, GaAsP, GaP of conventional materials can not be reached.

1991 Toshiba Co of Japan and the United States HP company developed InGaA1P 620nm orange ultra-high brightness LED 1992 InGaA1p590nm yellow high brightness LED utility. The same year, the Toshiba Co developed InGaA1P 573Nm yellow green super high brightness LED, to light up to 2cd. In 1994 Japan Nichia Corporation developed InGaN 450nm blue (green) color high brightness LED. Thus, color display three colors to red, green, blue, orange and yellow colors of LED have reached the level of light intensity candela realized, high brightness, color, LED outdoor full-color display has become a reality.

LED development in our country started in 70s, the industry appeared in 80s. The country has about more than and 100 companies, 95% of the manufacturers are engaged in the production of the road after the package, the required core almost all imported from abroad. The "Five Year Plan" technological innovation, technology research, the introduction of foreign advanced equipment and key technologies, the LED production technology in China has taken a step forward.

In two, the performance in high brightness LED:

X in ultra high brightness red A1GaAsLED compared with GaAsP-GaP LED, has a higher luminous efficiency, transparent substrate (TS) A1GaAs LED (640nm) luminous efficiency is close to 10lm/w, GaAsP-GaP LED than red 10 times. Ultra high brightness InGaAlP provided by LED and GaAsP-GaP LED are the same color include: green yellow, green yellow (560nm) (570nm), yellow (585nm), yellow (590nm), orange (605nm), red (625nm red (640nm). Comparison of A1GaInP transparent substrate LED luminous efficiency and other LED structure and an incandescent light source, InGaAlP LED (AS) absorption substrate luminous efficiency is 101m/w, transparent substrate (TS) 201m/w, 590 in the wavelength range of 626nm than GaAsP-GaP LED luminous efficiency is 10 higher in the 560 - 20 times; 570 wavelength range is 2 higher than the GaAsP-GaP LED - 4 times.

Ultra high brightness InGaN LED provides blue light and green light, the blue wavelength range is 450 - 480nm, blue green 500nm, green 520nm; its luminous efficiency is 3 151m/w. Ultra high brightness LED current lumen efficiency has been more than the incandescent lamp with a filter, can replace the power of 1W within the incandescent lamp, but also can replace the power of the LED array incandescent lamp within 150w. For many applications, incandescent lamps are used to filter the red, orange, green and blue, and the use of ultra-high brightness LED can get the same color.

In ultra high brightness LED manufacturing AlGaInP and InGaN materials will be more (red, blue, green) ultra high brightness LED chips together, without filters can get all kinds of color. Including red, orange, yellow, green, blue, and its luminous efficiency has been more than incandescent lamp, fluorescent lamp is approaching. Luminous brightness has been higher than 1000mcd, can meet the needs of outdoor all-weather, full-color display, with LED color screen can show the sky and the sea, three-dimensional animation. A new generation of red, green, blue ultra-high brightness LED reached unprecedented performance.

In three, the application in high brightness LED: in 1 in information indicator in in vehicle signal indicator lights on the car: the car is the main direction of external lights, tail lights and brake lights; in the interior of the car is the main variety of lighting and display instrument. Compared with the traditional incandescent lamp, the ultra high brightness LED has many advantages, and it is widely used in automobile industry. LED can withstand strong mechanical shock and vibration. The average working life of MTBF is higher than the number of orders of magnitude higher than incandescent bulbs, far higher than the working life of the car itself, so the LED brake lights can be packaged as a whole, without having to consider maintenance. Al.GaAs LED and AlInGaP transparent substrate with a filter compared to incandescent bulbs with high luminous efficiency, so that the LED brake lights and direction of light can drive current working under low driving current, only the incandescent lamp of the typical 1/4, which lowers the car for driving distance. The lower electric power can also reduce the volume and weight of the internal circuit system of the vehicle, and can also reduce the internal temperature rise of the integrated LED signal lamp, and the utility model can allow the lens and the outer cover to use the plastic with low temperature resistance. The response time of the LED brake light is 100ns, the response time is shorter than that of the incandescent lamp, so that the driver has more reaction time, thereby improving the safety of driving. The illumination and color of the external indicator of the car are clearly defined. Although the interior lighting of the car is not controlled by the relevant government departments, such as the external lights, the