GB/T 5702-2019 PDF English
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Method of measuring the color rendering properties of light sources
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| GB/T 5702-2003 | English | 170 |
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Methods of measuring the color of light sources
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Method of evaluating colour rendering properties of light sources
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GB/T 5702-2019: PDF in English (GBT 5702-2019) GB/T 5702-2019
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 17.180.20
A 26
Replacing GB/T 5702-2003
Method of Measuring the Colour Rendering Properties
of Light Source
ISSUED ON: MARCH 25, 2019
IMPLEMENTED ON: OCTOBER 01, 2019
Issued by: State Administration for Market Regulation;
Standardization Administration of PRC.
Table of Contents
Foreword...3
Introduction...4
1 Scope...5
2 Normative References... 5
3 Terms and Definitions...5
4 General Requirements...6
5 Measurement of Light Source (Relative) Spectral Power Distribution... 6
6 Calculation of Colour Rendering...7
7 Report on Calculation of Colour Rendering...13
Appendix A (Informative) Other Evaluation Index and Calculation Method of
Colour Rendering of Light Source...14
Appendix B (Normative) Visible Light Spectrum Reflectance of Standard Color
Sample...16
Appendix C (Normative) Characteristic Vector of Standard Illuminator D... 23
Appendix D (Normative) Colour Matching Function of CIE 1931 Standard
Chromaticity Observer...24
Method of Measuring the Colour Rendering Properties
of Light Source
1 Scope
This Standard specifies the general requirements for the evaluation on colour
rendering of light source, the measurement of spectral power distribution of light
source and the calculation of colour rendering.
This Standard is applicable to the evaluation of the colour rendering of light sources
that meet the requirements of white light sources.
2 Normative References
The following documents are essential to the application of this document. For the
dated documents, only the versions with the dates indicated are applicable to this
document; for the undated documents, only the latest version (including all the
amendments) is applicable to this document.
GB/T 5700 Measurement Methods for Lighting
GB/T 7922 Method of Measuring the Colour of Light Sources
CIE 127 Measurement of LECs
3 Terms and Definitions
For the purposes of this Document, the following terms and definitions apply.
3.1 Colour rendering of a light source
The influence of the light source spectrum on the colour appearance of the object.
This influence is caused by the observer intentionally or unintentionally comparing it
with the colour appearance under the reference illuminator.
3.2 Colour rendering index
The colour fidelity that reflects the colour rendering of the light source. It is expressed
by the degree of coincidence between the colour of the object under the light source
5.1.5 The measurement light repeatability of the spectroradiometer shall be better
than 1%.
5.2 Measurement methods
5.2.1 When measuring the colour rendering of the light source in the laboratory, the
light source (relative) spectral power distribution shall comply with the measurement
methods of spectral irradiance, total spectral radiant flux, partial spectral radiant flux
and spectral radiance specified by CIE127.
5.2.2When measuring the colour rendering of the light source on site, the light source
(relative) spectral power distribution shall conform to the measurement methods of
spectral irradiance and spectral radiance specified in GB/T 5700.
5.3 Laboratory test conditions
5.3.1 The ambient temperature shall be (23±2) °C, and the relative humidity of the
environment shall be no greater than 65%.
5.3.2 The light source to be measured shall be tested under rated conditions, and the
power supply equipment shall comply with the following provisions:
a) The harmonic content of the A.C. input voltage shall be less than 3%, and the
deviation of the power frequency from the rated value shall not exceed 0.5%;
b) The uncertainty of the input voltage and current monitoring equipment shall not
exceed 0.2%.
5.3.3 Before measuring the colour rendering of the light source, the light source shall
be preheated.
5.3.4 The test site shall be free of ambient light that affects the test results.
6 Calculation of Colour Rendering
6.1 Calculation process of light source colour rendering
The calculation shall be carried out according to the calculation process specified in
Figure 1.
- after the chromaticity shift is corrected, the chromaticity coordinate of the ith
colour sample under the light source to be measured.
cr, dr – adaptive chromaticity shift of the reference illuminator, which shall be
calculated by Formulas (20) and (21) by the uv chromaticity coordinate of the
reference illuminator;
ck, dk – adaptive chromaticity shift of the light source to be measured, which shall be
calculated by Formulas (20) and (21) by the uv chromaticity coordinate of the light
source to be measured;
ck,i, dk,i – adaptive chromaticity shift of the ith colour sample, which shall be calculated
by Formulas (20) and (21) by u, v chromaticity coordinate of the ith colour sample
irradiated under the light source to be measured:
6.3.4 U*, V*, W* chromaticity parameters of the colour sample irradiated under light
source shall be calculated by Formulas (22), (23) and (24):
Where:
u, v – uv chromaticity coordinate of colour sample;
u0, v0 – uv chromaticity coordinate of reference illuminator.
6.4 Calculation of colour rendering
6.4.1 The colour difference ΔE of the colour sample irradiated by the light source to be
measured and reference illuminator shall be calculated by Formula (25):
6.4.2 The special colour rendering index Ri corresponding to each colour sample shall
be calculated by Formula (26):
Appendix A
(Informative)
Other Evaluation Index and Calculation Method of Colour
Rendering of Light Source
A.1 The necessity of supplementary evaluation index
Colour rendering index is an evaluation method based on the influence of light source
on colour fidelity. However, this method does not reflect the influence of factors such
as the increase in saturation caused by the colour difference of the colour sample
caused by the light source on human perception.
A.2 Calculation of the gamut area index of the light source
A.2.1 The colour gamut of the light source shall be calculated by Formula (A.1)
according to the standard colour samples specified in Table B.1; U*, V* shall be
calculated according to 6.3:
A.2.2 The colour gamut index Ga of light source to be measured can be calculated
according to Formula (A.2):
Where:
Gk – colour gamut of the light source to be measured;
Gr – colour gamut of the reference illuminator.
A.3 Calculation of chromaticity index of the light source
A.3.1 The chromaticity index of the light source can be calculated based on the
standard colour samples specified in Appendix B or the non-standard colour samples
determined by the user.
A.3.2 The chromaticity C *k,i of the colour sample irradiated by the reference illuminator
shall be determined according to the provisions of 5.2 of GB/T 7921-2008 as per the
tristimulus values of Xi, Yi and Zi calculated in accordance with provisions of 6.3.1.
......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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