Invented in the 1960s, it is the use of electrons and holes in semiconductor materials combined with each other and release energy, the energy band (Energy Gat,) rank changes, they release energy to light-emitting display. The LED has a small size, long life, low driving voltage, low power consumption, fast reaction rate, good shock resistance, it is widely used in the field of signal indicator, digital display. As technology continues to progress the development of ultra-bright LED has been successful, especially in the successful development of white LED lights, making it more and more used in the lantern decoration, and even the lighting in the area.
l super bright LED features
Compared with the traditional lighting, ultra-bright LED has the following advantages:
1) long life, reliability and durability, very low maintenance costs LED can be used continuously 105h, 100 times longer than ordinary incandescent bulbs;
2) high-efficiency can already reach 201m / w. Expected by 2005 will reach 501m / W [1], the LED) the spectrum almost all concentrated in the visible light spectrum, and its luminous efficiency up to 80% ~ 90
%, LED energy-saving lamp energy saving but also 1/4;
3) color, light color simple example, 12 inches of red traffic lights, it uses low-efficiency 140W incandescent lamp as a light source, generated by 2000lm white The red filter, the light loss of 90%, leaving only under 2001m of red, 18 red LED light source lamp used in Lumileds Lighting Company, including circuit losses, consumes only 14W, and can produce the same luminous efficiency;
4) light speed fast car lights is an important area of application of the LED light source, LED response speed (ns level), the high level LED brake lights, installed in the car can reduce rear-end accidents.
Bright LED in recent years has been in a car near light applications, such as the German Audi Audi A86.O, Italy Fioravanti concept car introduced at the 2003 Geneva Motor Show, the Yak, the U.S. Ford Motor Company recently at the Detroit Motor Show launched ModEL U are beginning to be bright LED used in the design of the headlamps.
Despite the ultra-bright LED has many advantages, but there are still the following shortcomings:
1) low power single LED tube market power generally in 5W following, not yet more high-power LED, which is the biggest bottleneck of LED difficult to become a lighting preferred;
2) the need to strictly control the temperature LED is a semiconductor material, with the diode as the PN junction diode highlight the power is relatively large, so the same with the power semiconductor devices, need to consider the problem of heat dissipation, junction temperature is too high will directly affect the LED life, and increased LED light decline in serious cases, the LED burned out;
3) the high price in addition to low power, the price is the main factor of the LED is difficult to become a lighting Although the LED has been most understanding, most people optimistic, but its high price is difficult to be accepted by consumers, the current single yellow LED about O. 6 yuan / month, green and blue single LED at about 1.8 yuan / the price of the white LED of about 2.2 to 5.5 yuan / month; dozens of single LED portfolio, the cost will greatly increase such as an LED installed in lawn lamp, the unit price is equivalent to general lawn several times, the LED to become a mainstream light source of lighting in the future, it must be moving in the direction of the large lumen, the cost of it be possible to reduce the market possible breakthrough.
Characteristics of the two super bright LED flood lights
HPWA-xH00 Lumileds Lighting Company, a super bright LED, it as an example the analysis of ultra-bright LED features. Figure 1 is the forward voltage drop (VF) and the forward current (IF) curve, the curve shows that when the forward voltage exceeds a certain threshold (about 2V), commonly referred to as the turn-on voltage can be approximated that , IF and VF is proportional to. Table 1 shows the electrical characteristics of the major super bright LED. Table 1 shows, the super bright LED’s highest IF up to 1A, VF is usually 3 ~~ 4V.