Development of China's LED detection technology


In the LED detection technology, because of the difference between the properties of LED product with the traditional light source. The LED luminous and junction temperature are closely related, in optical LED products and photoelectric parameter testing, junction temperature change environment temperature, radiator or shell temperature will change LED, thus affecting the light output. In photometric test of LED lamp, is often the light emitting devices and lamp shell is not separable, need one test, usually by absolute photometry method. Some high brightness LED light can cause eye retinal photochemical injury, according to IEC62471 "lamps and lamp systems biological safety standards" series, the photochemical damage LED product testing, is currently the industry one of the focuses in the field. In addition, LED product has long life characteristics, we can not like ordinary lighting products for long-term fire test, must adopt the test method accelerated certain, predict the effective life of LED products, such as American "Energy Star" by the LM80 standard, our country is developing the LED life accelerated test method standard.

Therefore, in recent years in international LED product performance measurement and test equipment development. In our country, with the rapid development of LED industry, detection technology and equipment innovation ability to significantly improve, launched a series of meet the need of advanced detection equipment industry; especially in the LED products and energy efficiency testing, optical lamp spatial light distribution measurement, the accelerated life test, optical radiation safety inspection etc. the development of the advanced detection equipment, with international competitiveness.

Optical and energy efficiency testing, LED product

In the performance testing of LED products, the temperature control is very important. According to the domestic and overseas standards, LED device control the junction temperature or housing hot spot temperature; for the LED module, control module is the hot spot temperature heat sink; and the application of LED products, the ambient temperature as a benchmark. Therefore, in the optical and energy efficiency in the detection of LED products, the LED device, module and application products, is very important to temperature control in the test apparatus.

Beam some LED products of the directivity is strong, measured in the integrating sphere, light beam projection area, screen position sensitive, the IESNALM79 standard and the CIE127 technical report made provision, the higher the spectral reflectance of 1 ball wall coating materials. USA NIST in promoting the international LED Standard Test method standard, walking in the forefront of the world, also put forward high requirements on test equipment. Figure 1 isothermal integral ball, is the LED standard test equipment development Zheda trichrome for NIST America National Institute of standards and technology, the LED device, module, application of products such as the three LED products to realize constant temperature test.

Light distribution detection of two, LED lamps and luminaires space

Distribution photometer is the measurement of light source and the light emitting device space photometric intensity distribution. Figure 2 is the schematic structure of a reflector is recommended by the International Commission on illumination distribution photometer CIE70 file meter, mirror always around the center axis, between the reflector and the photometric detector can precisely arranged a series of stray light elimination aperture, very effective to eliminate stray light. The distribution photometer for more suitable for various complex spatial beam light distribution measurement, has been adopted by more than one hundred laboratories worldwide, the use quantity first. Several national laboratory in China have adopted this mirror distribution photometer.

In recent years, with the rapid development of LED technology, LED product of the spatial light distribution measurement is more and more domestic and international attention. Compared with traditional light sources and lamps, LED lighting products are beam distribution is more complex, there may be some differences in color space, so LED products on the spatial light distribution measurement put forward new demands, not only to the spatial intensity distribution test of LED, at the same time to measure the spatial color inhomogeneity distribution. In addition, for many laboratory, space restricts the application of high performance equipment, in order to save space, China has developed the luminosity distribution two piece of mirror.

Large photometric test equipment developed in China meter tracking mirror type distribution photometer. It used in LCD motion artifacts measurement in optical tracking measurement method, to solve the previous measuring beam axis of several circular motion reflector type distribution photometer is not fixed, stray light elimination, or photoelectric detector in a series of problem space motion. Combined with the advantages of central rotating mirror type distribution photometer and circular motion reflector type distribution photometer, measurement fixture position remains unchanged, the measuring beam perpendicular incident detector, photoelectric detector position remains stationary; a plurality of stray light elimination diaphragm is arranged in the measuring light path, can almost completely eliminate the test chamber floor, walls and ceilings of stray light reflected from each other. At the same time, new high resolution color measurement system specially designed, can achieve spatial color quickly and accurately measured LED module or luminaires distribution. The distribution photometer measurement range, small occupied area, high measuring precision, satisfy the measurement requirements of CIENO.70, CIE121 and BSEN13032 and other international standards.

Optical radiation safety testing and evaluation of three, LED products

With the development of light in biological research, optical radiation safety problem more and more cause for concern. Especially the rapid development in recent years of LED, the power and the external quantum efficiency of the chip greatly improved, high-power blue LED chip has been widely used in the field of general lighting; the development of high power multi chip integration and two optical technology, so that the light radiation hazard LED more exciting



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