GB/T 5702-2019 in English

《GB/T 5702-2019光源显色性评价方法》由TC120（全国颜色标准化技术委员会）归口，主管部门为国家标准化管理委员会。

ChinaStandards.net is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative.

This standard is developed in accordance with the rules given in GB/T 1.1-2009.

This standard replaces GB/T 5702-2003 Method of measuring the color rendering properties of light sources. In addition to a number of editorial changes, the following main technical changes have been made with respect to GB/T 5702-2003:

——the application scope of the standard is modified;

——the color rendering measurement is added;

——the calculation flow of color rendering of a light source is added;

——the quantitative measuring methods such as color gamut index and chroma index of light source are added as informative;

——the data in Annexes B, C, D are modified.

This standard was proposed by and is under the jurisdiction of National Technical Committee on color of Standardization Administration of China (SAC/TC 120).

The previous editions of this standard are as follows:

——GB/T 5702-1985 and GB/T 5702-2003.
 
Introduction

The color rendering of a light source is an important technical index for measuring the light source property and light environment quality, which has been adopted by many standards including GB 50034 Standard for lighting design of buildings and JGJ 153 Standard for lighting design and test of sports venues.

GB/T 5702-2003 Method of measuring the color rendering properties of light sources specifies the basic method for measuring the color rendering of a light source. Since the implementation in 2003, the standard has played an important guiding role in improving the light color quality of light sources and creating a healthy and comfortable light environment for people. However, relevant researches show that this method can only reflect the fidelity of light source color, but cannot fully reflect the color rendering of a light source. In recent years, with the rapid development of LED technology, especially in the application of multi-chip mixed light LED, this problem is increasingly prominent. At present, the Illuminating Engineering Society of North America (IES) has issued a new technical memorandum TM-30 Method for evaluating color rendering of a light source, adding color gamut index and other evaluation index for color rendering of a light source.

In the process of revising this standard, in view of the fact that the method of measuring the color rendering properties instead of CRI has not yet reached a broad agreement in the world, the standard compilation team has determined the principle of revising the standard after careful investigation and scientific argumentation, that is, on the basis of basically keeping measuring method of the original standard unchanged, the measuring parameters of the color gamut index, color rendering index and other light sources on the color rendering effect of the object are supplemented in the form of informative, thus ensuring the continuity and stability of the standard method, providing more choices for users and more accurately reflecting the influence of light sources on the viewing effect of the object.

Method of measuring the color rendering properties of light sources

1 Scope

This standard specifies the general requirements for measuring the color rendering of a light source, measurement of light source spectral power distribution, calculation of color rendering, etc.

This standard is applicable to the measuring of color rendering of a light source that meets the requirements of white light sources.

2 Normative references

The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

GB/T 5700 Measurement methods for lighting
GB/T 7922 Methods of measuring the colors of light sources
CIE 127 Measurement of LEDs

3 Terms and definitions

For the purposes of this standard, the following terms and definitions apply.

3.1
color rendering of a light source
influence of light source spectrum on color appearance of objects, which is caused by the observer intentionally or unintentionally comparing it with the color appearance under the reference illuminant

3.2
color rendering index
it reflects the fidelity of the color rendering of a light source and it is expressed by the degree of conformity between the color of the object under the measured light source and the color of the object under the reference illuminant

3.3
general color rendering index
Ra
the average value of the color rendering index of the light source to the standard color samples No.1 to No.8 specified by the International Commission on illumination (CIE)

4 General requirements

4.1 The color rendering of a light source shall be quantitatively evaluated by color rendering index, or by reference to color gamut index, chroma index, etc. of light sources in Annex A.

4.2 The color difference Δc between the measured light source and the reference illuminant shall be less than 5.4×10-3.

4.3 The selection of color samples for measuring the color rendering of a light source shall meet the following requirements:

a) color samples shall be determined according to Annex B;

b) the general color rendering index shall be determined according to the standard color sample specified in Table B.1.

4.4 The visible light spectral reflectance of the color sample used for measuring the color rendering of the light source shall be determined according to Annex B, and the wavelength interval may be reduced by interpolation.

5 Measurement of light source (relative) spectral power distribution

5.1 Performance requirements of spectral radiometer

5.1.1 The wavelength range of the spectral radiometer shall be 380 nm to 780 nm.

5.1.2 The wavelength accuracy of the spectral radiometer shall not be less than ± 0.5 nm.

5.1.3 The bandwidth of the spectral radiometer shall not be greater than 5 nm.

5.1.4 The detector shall work within the linear range.

5.1.5 The repeatability of the measured light of the spectral radiometer shall be better than 1%.

5.2 Measurement method

5.2.1 When the color rendering of a light source is measured in the laboratory, the light source (relative) spectral power distribution shall conform to the methods of measuring spectral radiant illuminance, total spectral radiance flux, partial spectral radiance flux and spectral radiance specified by CIE 127.

5.2.2 When the color rendering of a light source is measured on site, the light source (relative) spectral power distribution shall conform to the methods of measuring spectral radiant illuminance and spectral radiance specified in GB/T 5700.

5.3 Test conditions of laboratory

5.3.1 The ambient temperature shall be (23±2)℃ and the ambient relative humidity shall not be greater than 65%.

5.3.2 The measured light source shall be tested under rated conditions. The power supply equipment shall meet the following requirements:

a) The harmonic content of AC input voltage shall be less than 3%, and the deviation between power frequency and rated value shall not exceed 0.5%;

b) The uncertainty of input voltage and current monitoring equipment shall not exceed 0.2%.

5.3.3 Before measuring the color rendering of a light source, the light source shall be preheated.

5.3.4 The test site shall not have ambient light that affects the test results.

6 Calculation of color rendering

6.1 Calculation flow of color rendering of a light source

The calculation shall be carried out according to the calculation flow specified in Figure 1.

Foreword i
Introduction ii
1 Scope
2 Normative references
3 Terms and definitions
4 General requirements
5 Measurement of light source (relative) spectral power distribution
6 Calculation of color rendering
7 Calculation report of color rendering
Annex A (Informative) Other measuring indexes and calculation methods of color rendering of a light source
Annex B (Normative) Visible spectral reflectance ratio of standard color samples
Annex C (Normative) Characteristic vector of standard illuminant D
Annex D (Normative) Observer color matching function of CIE 1931 standard chromaticity