LED unresolved problems with 2008 - New LED Floodlight

Theoretically LED Floodlight brightness is over 300lum per watt. However, actually it is only about 70lum. Comparing with the energy-saving fluorescent lamps, the demerit is obvious, such as the price. How to represent the merits of the LED Floodlight thoroughly? It is a quite different and urgent technical problem for the LED Floodlight workers.

Problem 1: How to improve the LED lighting luminous efficiency problem.
The way to improve the LED Floodlight efficiency problem is ameliorating the structure and produce technique of semiconductor material and LED CMOS chip. It is rather different to achieve 200 lumens/watt recently because of this job requires powerful theoretic research and semiconductor technique equipment. Though the traditional cold cathode fluorescent lamp CCFL is high power consumption, caporal luminous, the luminous efficiency is achieve 50-100 lm / W. While the luminous efficiency of the white light LED Floodlight is only 20lum per watt or even lower in the beginning, which is destined to be not suitable for backlight of LED monitor. But the luminous efficiency of the white light LED is increasing by the rate 60%. So far, the luminous efficiency of the white light LED is breakthrough 50 lum per watt, can be used in daily life.

Problem 2: High-power-life
Due to the lamp-house for illumination is stricter than the lamp-house for show, the white light LED power should be high as soon as possible. In the current work, with the working time longer and longer, the bad light with phosphor and packaging materials itself, all these factors above will lead the luminous flux decline.  The end of the availability life’s definition is luminous flux decline to certain percentage numerical value. As used for lighting, the single LED output luminous flux must as high as possible. If we want to enlarge the luminous flux, we should supply enough electric power at first. But the temperature rising of the LED CMOS chip should be slowly or each capability especially the life will be affected. Obviously, to make high output power LED Floodlight and equipment not only need wide chip but also well cooling structure.

Problem 3: The reasonable structure of the lamp
Due to the LED Floodlight need serious LED canal, the dispersion of parameters is also a technical issue. Except pre-selection, classification, the reasonable structure of the lamp (including the collection and position) and suitable drive circuit in order to avoid the the concentration of energy burned part of LED.

Problem 4: Search for simple and effective drive circuit
Due to the light is combining of several LED, the LED will carry out parallel, serial inevitably. If one LED short circuit or open circuit, the whole piece or the whole LED will be off. We must study a simple and cheap protection circuit so that we can adverse effects to a minimum.

Problem 5: The cost problem—replace of CCFL
The cost of LED backlighting system is higher than cold cathode fluorescent tube. At present the price of LED backlighting modules and the components is 5 times higher than CCFL backlight, the wider the screen size, the higher technical for LED backlight. But with the increase in production capacity, the cost of LED backlighting source will rapidly decline.

Problem 6: The cooling of the chips
Due to the LED chip average surface area are less than 1mm, and the heavy working current density, diode heats severely. If not leading, the chip will be damaged. Because of the light is combing of some LED, long working time leading rising temperature, so we must strengthen cooling. So the LED lamp-house will get bigger. This factor increases the difficulty for designing the shape of the lamp.

With large potential energy-saving and good illumination capability, the LED opens a new technical field for us. But we also face some technical and system obstacles mentioned above. When we design the light, we should take a rational approach to look at the application of LED, knowing the LED truly, use LED according to the environment conditions. Follow those principles we can create an energy-saving and high quality lighting circumstance.