The "General Rules for White LED Metering for Lighting" jointly developed by the four groups in Japan is currently the only measurement standard for white light-emitting diodes (LEDs) for lighting. This article will introduce and analyze its contents for readers and related products. , study, research department reference.
White LED standard is released
With the rapid development of LED R&D technology, it has been regarded by many as the main lighting source of the new generation with full potential. However, LED has different spatial illumination characteristics from traditional illumination sources, which may not be suitable for the measurement of optical characteristics of traditional light sources. For LEDs, such as Luminous Flux, Luminous Intensity, and Chromaticity, LED measurement accuracy and accuracy will be problematic. Therefore, the world's major standards associations have revised or added LED measurement standards, but because of the wide variety of LED packages , performance is also different, so there are also associations to develop new measurement standards for LEDs for different purposes.
Take the International Commission on Illumination (Commission Internationale de l''''Eclairage; CIE) as an example. In 2007, it revised the original LED measurement technology file CIE-127. However, due to many disputes, there are still many measurement problems to be solved. Leading by the US Department of Energy (DOE), in conjunction with the promotion of solid-state lighting products, a standards development group consisting of the American National Standards Institute (ANSI) and the North American Lighting Society (IESNA) is conducting standards for solid-state lighting. The formulation of this article (this article has been introduced in the previous B7 version of the newspaper), including standards such as optical rotation measurement, color measurement and life assessment, but these standards are characterized by the fact that solid-state lighting is regarded as a Overall evaluation, that is, LED cells cannot be measured by these standard specifications.
In recent years, China has also been committed to the promotion of semiconductor light-emitting device standards. With the support of the government, semiconductor light-emitting device test methods have been introduced, and other relevant standards are under review.
However, the fastest-growing country in the promotion of white LED standards for lighting is Japan, including the Japan Lighting Society (JIES), the Japan Lighting Commission (JCIE), the Japan Lighting Industry Association (JIL), and the Japan Electric Ball Industry Association (JEL). In 2004, four common standards "General Rules for White LED Metering for Lighting" have been established, which has become the only measurement standard for white LEDs for lighting. It has been the first to develop several unregulated standards in the first edition. Projects such as the manufacture of standard LEDs, the measurement of light intensity of small modules, and the method of life assessment.
In view of the progress of LED measurement methods and the expansion of standard content, the four groups announced the revision of this standard in March 2006, adding and revising the original standard content, measurement of colorimetry and luminous flux. More detailed specifications are made, such as measurement methods. However, based on the cautious mentality, many parts are still placed in the subsidiary part instead of the actual standard. However, the description of the relevant specifications is still very detailed. At this stage, the international standard can be found in the LED standard literature. It can be said that it is the most complete specification of content. This standard will be a very important reference when the industry still lacks appropriate general LED measurement specifications. The following highlights the important provisions of this standard, as well as the supplements to the revised version.
The scope of application is limited to white LEDs for lighting
In the initial title of the standard, it has been declared that the scope of application is limited to white LEDs for illumination. It is considered that the measurement target is limited to white LEDs for illumination, so that the measurement method compared with the standard LED can effectively improve the measurement accuracy, and The content of standard LEDs is very detailed. In the measurement part of the light intensity, the measurement is carried out according to the standard conditions specified by the International Commission on Illumination; in the measurement part of the luminous flux, the integration sphere is used for measurement, and the chromaticity and correlated color temperature are added in the revised version (Correlated). Color Temperature; CCT), Color Rendering Index (CRI), etc., and in principle use an integrating sphere as its incident optical system.
This standard is mainly for the specification of single LED, but its measurement of the light intensity of small LED modules is also included in the specification. For small LED modules, it is not necessarily applicable to the average LED light intensity specified by CIE standard conditions. Measurement methods.
Lighting white LEDs are clearly defined
The biggest difference between this standard and other LED related standards is the clear definition of "white LED for lighting". According to the interpretation of this standard, the so-called "white LED for illumination" has a light color that measures the luminous flux or the average light intensity, and the spectrum must cover the entire range of the visible light field, and there must be no missing parts; the relevant color temperature The range is within (2500~10000)K; and the correlated color temperature is on the CIE 1960 Uniform Chromaticity Scale (UCS) coordinates, and the deviation from the Planckian Locus (Duv) must be less than 0.02. condition.
It is worth noting that in this definition, RGB tri-color LEDs will be excluded from the range of white LEDs for illumination. In fact, in the interpretation of the annex to this standard, the definition of illuminated white LEDs is a controversial project. In terms of the relevant color temperature, since it is for general lighting, it is considered at the same level as the fluorescent lamp (the relevant color temperature is about (2700 ~ 8000) K), but it is based on the actual development of white LED. According to the technique, the range of the correlated color temperature is set to be in the range of (2500 to 10000) K.
Light intensity / luminous flux is two mass measurement methods
Since there is no standardized and uniform LED package shape, size and light distribution characteristics, but different design structures are generated according to various purposes, LED measurement is difficult. Therefore, the structure, performance, and reproducibility of standard LEDs must be specified.
In this standard, standard LEDs are mainly divided into light intensity measurement and luminous flux measurement (see Table 1), which have different design concepts depending on the measurement characteristics. For example, a standard LED for light intensity measurement, because in the light intensity measurement method, the mechanical axis of the LED to be tested (Photo A Detector) is an important correction factor, so The standard uses a bullet type that is easy to align with the mechanical shaft as a standard form. As for the standard LED for luminous flux measurement, it is used to prevent the light from being emitted toward the rear of the LED due to the measurement of the total luminous flux. A uniform metal can (TO-Can) package is standard. It is worth noting that the two types of standard LEDs here are white LEDs made of indium gallium nitride (InGaN) series chips combined with yttrium aluminum garnet (YAG) phosphors, which correspond to the definitions. The portion of the white LED that is used for illumination without missing wavelengths.
Since standard LEDs are an important reference for measurement, the standard is expected to minimize the instability of optical and electrical characteristics to minimize the effects of the surrounding environment to achieve the desired reproducibility requirements. In addition to limiting the measurement ambient temperature variation to less than 2 °C, in order to reduce the initial variation of LED, it is recommended to use a standard LED that has been driven by a constant current (such as 20 mA) for more than 100 hours. The ambient temperature of the standard LED must be controlled. At 25 ° C. In the revised version, it adds a temperature control socket (Socket) for the lighting fixture with chip temperature control in Annex 4, which requires the LED to reach the thermal equilibrium state under constant current conditions (hopefully at least The lighting measurement was performed after 5 minutes or more.
Gfci Socket,Gfci Electrical Socket,Gfci Light Socket,Customized Socket
Junction Box,Switch Co., Ltd. , http://www.nbsocket.com