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Talking about the energy efficiency of LED light source

Update:11-06-2018

LED, simply understood, is a semiconductor light-emitting diode, is the world's most advanced solid-state lighting technology. LED lights are not the old faces of filaments and light bulbs, but solid-state light sources using semiconductor chips. It uses electronic movement to emit light and directly converts electrical energy into light energy. Therefore, the LED's power consumption is low and the service life is high. When a typical high-quality energy-saving lamp can be used for about one year to recover the cost, the maintenance cost of the high-power LED light source is low, and the return on one-time investment is more obvious.

Although most of energy-saving lamps than the incandescent lamp energy-saving effect is obvious, but in essence is still a fluorescent lamp, low-pressure mercury vapor discharge by irradiation of rare earth trichromatic phosphor to light, can only be made into double-end slender tube. Moreover, many mercury lamps contained in the energy-saving lamps are harmful to the environment. If people discard them after they have been scrapped, it is prone to energy-saving and environmental protection. Semiconductor solid-state light sources such as LEDs are fundamentally different from fluorescent lamps. Semiconductor lighting uses a cold light source, does not require inflating, does not require a glass enclosure, and does not add mercury. It can be described from the production process to the use process until the end of life. No pollution. In addition, LED lighting also has good color rendering, no flicker, and soft light.

Foreign countries have issued many policies and regulations to encourage the production and use of energy-saving lamps to achieve energy-saving goals. According to reports, the latest energy law passed by the U.S. Congress has set the timeline for the elimination of traditional light bulbs. At present, the EU market no longer sells incandescent light bulbs. The EU countries not only compensate enterprises that develop low-cost, long-life energy-saving lamps. It also compensates for difficult families who purchase energy-saving lamps. Based on the LED lighting technology developed by the efficacy of lamps, is expected to increase in the next 10 years 1 to 2 times.

The performance of a light source, energy efficiency, can be measured by the ratio of its power to the brightness it produces, expressed in lumens per watt (lm/W). An ordinary Philips 60W frosted incandescent lamp can produce 890 lumens of brightness, so the energy efficiency of the light source is 15.8lm/W. Depending on the type of lamp package, the actual performance of the lighting device may significantly decrease. For example, if you put a standard incandescent light bulb in a recessed light source and use a reflector to reflect the light source, you will end up with only 50% of the lighting efficiency due to the loss of the mirror. The energy efficiency of the entire lighting device becomes 7.5lm/W.

We can often see that some LED manufacturers claim to further increase the lm/W performance of LED lighting sources. For example, the research plan developed by DOE is to increase the efficiency of SSL light sources in the field of commercial lighting from the current 30 lm/W to more than 150 lm/W. According to the current energy star program for SSL recessed lighting devices, we can calculate the overall energy efficiency of SLL lighting devices constructed using existing components. For lighting with an aperture slightly larger than 4 inches and a correlated color temperature (CCT) of 3000K. The device has a minimum brightness of 500 lm and a minimum light source efficiency of 35 lumens per watt.

The performance of cold-white LEDs has doubled in the past two years. If the energy efficiency of warm white LEDs has a similar performance improvement, we will be able to see warm white LEDs with 80lm/W in the near future.

The choice of isolated driver also plays an important role in improving the energy efficiency of the entire lighting device. This is currently a trade-off choice between price and performance. Linear drives are the lowest price, but their energy efficiency is in the range of 50% to 60%. Switching drives have the highest energy efficiency, typically between 80% and 85%. To achieve higher energy efficiency, more complex circuits are needed, so the cost of the drive is higher.

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