LED lamps can also be called light engines.

LED light engine refers to the LED package (components) or LED array (modules), LED driver, and other luminance, thermal, mechanical and electrical components of the overall combination. The device is connected directly to the branch circuit through a conventional connector that matches the LED lamp. The LED lamp scheme does not use a standard lamp holder.

This definition seems to be perfect, but it usually leads to temptation.

Professor Mao Yuhai summed up a more shallow definition of LED light engine, that is, LED light source + constant current drive power installed on an aluminum substrate.

Professor Mao Yuhai, an expert on LED networks in China, is well-known in the industry and has a long list of bright titles: Associate Fellow of the College of Electrical Engineering, Cornell University, Senior Member of the Institute of Electrical and Electronic Engineers, Professor of Electronic Engineering, Tsinghua University, Member of the Chinese Electronics Society, Senior Member of IEEE, Stanford, USA Visiting professor, deputy director of Radio Electronics Research Institute, Tsinghua University. It was added again: Chairman of the company.

Can the whole LED lamp also be called the light engine? Yu Hai pointed out, of course not. Just as the whole car can not be called an engine, the engine is the car's power assembly, but not the same as a car, but also add a shell talent to become a car. The reason why we need such a product is because all lights have various appearance. Some lamps can even be called works of art.

In the case of incandescent lamps, it can be said that it only needs the simplest bulb one way, plus at most candles or minimal Christmas lights. But its shape is varied. In particular, the crystal lamp is a variety of Arts and crafts, the most beautiful. But LEDs also have to be powered by a constant-current drive source with poles cluttered, equivalent to an incandescent lamp (which can be turned on at 220V). If the LED is made into a light engine, it can be turned on like an incandescent lamp connected to 220V (and, of course, a matching radiator is needed). On the one hand, this helps to standardize, on the other hand, it can greatly facilitate the shell (and radiator) program to carry forward its capabilities.

Technical difficulties of LED optical engine

To drive the constant current source to LED lamp board, the first difficulty is space.

Take the bulb lamp as an example: suppose that there are more than 30 components in the common switching constant current source on the LED aluminum substrate, and there are large inductance, transformer and large capacitance, the components will block the light, the more the components, the worse the reliability. Therefore, the switch constant current source is not available.

In this case, it can be processed by linear constant current power supply.

But at the same time, Yu Hai indicated that choosing the usual linear constant current source is not a feasible optical engine scheme. Although it addresses the space-occupying problem, the linear flow source has low power, especially at high-market power, and, in other words, high calorific value.

Wherever the power source is, its heat is always dissipated through the radiator into space, but when the power source and the lamp board are placed together, the power consumed by the power source will become heat and be added directly to the lamp board, which will increase the heat dissipated by the lamp board, which will increase the junction temperature of the LED and reduce its life.

This also highlights the second technical difficulties of light engine heat dissipation.

Taking a 10-watt LED bulb lamp as an example, the power supply is assumed to be 85% (the higher the market voltage of the linear constant current source, the lower the power), that is, the driving LED power is 8.5 watts, and the power consumption is 1.5 watts.

Assuming that the power of LED is 30%, that is, 70% of the power becomes heat and needs to be emitted. Now with the 1.5W of the power supply, it will become the power of 7.8W, which will increase 19.2 of the heat. Integrating this power into the aluminum substrate also increases the junction temperature of the LED by 15.8% (because one is loose to the radiator). Assuming that the junction temperature of the LED was originally 85 degrees Celsius, the junction temperature of the LED will now increase to 98.4 degrees Celsius, which will reduce the life of the LED.

In this case, only a very high-power linear constant-current source is required to complete the optical engine, and its benefits lie in high power and light efficiency stability. Efficient driving reduces overall heat.