女人天堂AV在线

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    In-depth analysis of LED street light detection technology, standards and development prospects

    Under the slogan of low-carbon energy conservation, LED lighting has been vigorously launched, and the LED street lamp industry has developed particularly rapidly due to the strong guidance of the government's a€?Ten Cities and Ten Thousandsa€? policy. According to iSuppli's data, more than 50% of domestic LED lighting manufacturers focus on LED street lighting. "The 'Ten Cities and Ten Thousand' project has not installed more than 1 million street lamps, but there are thousands of manufacturers doing this project." Qian Keyuan, deputy director of the Semiconductor Lighting Laboratory of Shenzhen Graduate School of Tsinghua University pointed out. It can be seen that the government policy gives the manufacturers great confidence. However, until now, the detection results of LED street lamps have not been satisfactory. When analyzing technical problems such as light efficiency, light decay, light distribution, and color temperature, the loopholes in the detection method are gradually exposed. If the means of detection are not scientific, LED lighting, a sunrise industry, may be greatly dragged.

    LED street light problem representation analysis

    "In the development of LED lighting technology, China is very special, because China is the LED street light products as the entry point of the industry. In fact, LED street lights are the most difficult products to design in LED lighting, so there will be many problems. Blocking the further development of LED lighting." Qian Keyuan said. At present, the test data of LED street lamps indicates that the reliability, light source life and light decay of the product are not up to standard. In 2009, Shenzhen conducted a comprehensive inspection of 27 LED street lamps. The test results show that the average light efficiency and energy consumption of LED street lamps is only equivalent to the level of 150W sodium lamps. This result has undoubtedly brought a lot to the LED street lamp industry. The negative impact. However, Qian Keyuan believes that through the analysis of the test results, many test methods and standards themselves have been exposed. These problems are worth pondering. "If the standards and methods of testing are unreasonable in themselves, they will lead to wrong guidance in this industry," he pointed out.

    a€?In 2009, we measured the products of dozens of LED street lamp manufacturers in Shenzhen. The significance is significant. Shenzhen is currently a marginalized LED application. The speed of developing and producing LED products is very fast, and the packaging is also very distinctive. The industrial accumulation is also very strong, but the scale of application is much smaller than other cities.

    This comprehensive inspection of LED street lights is expected to promote the development of LED street lamps in Shenzhen. However, when the results of the tests come out, people feel that the whole army has been wiped out. Qian Keyuan said frankly. However, through technical analysis of the products, experts believe that the results are not as bad as expected, and the test methods and standards have exposed many ills.

    The time span for testing LED street lights in Shenzhen in 2009 was 113 days, starting in spring and ending in summer. The LED street light being tested actually operated for 1,200 hours on the road. The test results showed that the average light decay of the outdoor test was 14.1%, and that of the indoors was 5.3%. "If the LED street light products are well sealed, the indoor and outdoor light decay should be similar unless the product is broken. The only difference is the indoor constant temperature, the outdoor temperature is changing." Qian Keyuan pointed out the test This key point in the middle.

    Through the analysis of the test results, Qian Keyuan summed up the six key factors affecting the test results, many of which are related to temperature.

    These factors include:

    1. The effect of temperature on the luminous flux of the LED chip . This effect is relatively large, about 0.02~0.03%/?°C.

    2. The effect of temperature on the output current of the drive circuit. The effect is not too large, about 0.01% / ?°C.

    3. The test starts in spring and ends in the summer with a temperature span of about 20 ?°C. The large temperature span is not conducive to the reading of the final result, especially the first test of light decay is in the cool spring, the last test of light decay is in the hot summer.

    4. Test equipment accuracy. The accuracy of the test photodetector includes parameters such as spectral matching error and temperature coefficient. The spectral matching of this test is not bad, but the temperature coefficient of the probe can not be ignored. At present, the standard temperature probe has a temperature coefficient of not less than 0.2%, so the probe will produce a 4% luminous flux test error during a test period of 2,000 hours and an ambient temperature change of 20 ?°C.

    女人天堂AV在线

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