I. International Lighting Commission (CIE), Technical Committee (TC) Technical Characteristics of Related LEDs Two divisions of the International Commission on Illumination (CIE), namely: D1 (Vision and Color Division), D2 (Light and Radiation Measurement) unit)
The D1 Division is studying the color rendering of white LEDs and related metering issues. D1: TC 1-65, TC 1-62 studied the visual measurement of the color chart and the color rendering of the LED, and the two draft documents have been forwarded. The TC 1-62 document "COLOUR RENDERING OF WHITE LED Light SOURCES" may partially replace the CIE 13.3-1995 publication, which has entered the voting phase.
The TC 1-62 document "COLOUR RENDERING OF WHITE LED LIGHT SOURCES" reviews the visual results of the white LED color rendering index CRI. The CRI calculation method is specified in the CIE 13.3-1995 publication. If the calculation of the CRI is inconsistent with the visual results of the white LED, the document does have this contradiction. The technical report concludes that CIE CRI does not apply if color rendering calculations including white LEDs are applied.
The Technical Committee recommends that D1 establish a new set of color rendering indices that do not immediately replace the current CIE color rendering index calculations. These new color rendering indices complement CIE CRI and combine new color development in successful applications. After the index, it is determined to replace the current CRI calculation method.
D2 set up a special technical committee TC 2-45 to study the measurement method of LED: TC 2-45 file "MEASUREMENT OF LEDS" is voting, it will replace CIE 127 publication.
Second, LED luminous efficiency limit value For a long time, semiconductor research experts explore various new technologies to improve the internal and external quantum efficiency of LED. In 2006, there have been reports on the luminous efficiency of low-power white LEDs exceeding 100 lm/W. In order to establish a reasonable expectation of LED luminous efficiency, it is necessary to calculate the LED luminous efficiency limit value based on photometry and colorimetry.
In October 1979, the 10th International Metrology Conference (CGPM) defined New Candela (cd): Candela (cd) is the luminous intensity of a light source emitting a monochromatic radiation frequency of 540.0154X1012 Hz (wavelength 555 nm) in a given direction, in this direction The radiation intensity on is:
1cd=(1/683)W /sr (wavelength 555nm)
1cd=1 lm/sr
1W=683 lm (wavelength 555nm)
If the power loss, internal quantum efficiency, and external quantum efficiency values ​​are ignored, the luminous efficiency limit values ​​of various light sources and LEDs can be calculated. Figure 1 shows the x and y coordinates of the ideal isochromatic white light on the CIE 1931 chromaticity diagram, and Figure 2 shows the spectral efficiency of the human eye.
Figure 1 Figure 2
In the field of illumination, the birth of a novel light source, life and light efficiency are important quality indicators, and its color rendering properties for various colors are another important quality indicator of the lighting environment. The two yellow spectral lines of the low-pressure sodium lamp have a theoretical luminous efficiency of 450 lm/W (Fig. 3) and an actual luminous efficacy of more than 200 lm/W. However, due to its poor color rendering properties, it was eventually replaced by high pressure sodium lamps and metal halide lamps.
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