Temperature dependence correction method of LED filament lamp for total luminous flux calibration based on voltage measurement

Abstract

Light-emitting diode (LED) standard lamps are interesting since the traditional incandescent standard lamps for photometry are difficult to obtain. Many of the National Metrology Institutes have started projects to study the use of LED standards for photometric comparison. The National Institute of Metrology, China, has developed a type of LED filament lamp for total luminous flux. The lamp mimics the 4π incandescent standard lamp and has no space for an active temperature control component. A temperature dependence correction method is reported using the coefficient of the lamp voltage to the output luminous flux. The luminous flux correction is derived from the lamp voltage value. By applying correction, the stability test of the LED filament lamp shows that the ageing effect was estimated to be less than 0.1%/210 days. The temperature dependence was suppressed to less than 0.1% for a range of 21 • C ± 2 • C, which could be due to possible temperature fluctuations of the lamp ambient temperature during measurement by the goniophotometer or integrating sphere.

Characterization of the LED filament lamp for luminous intensity calibration

“…However, ambient temperature is not an optimal parameter to implement this correction, because there is a lag between the change of ambient temperature and the change of junction temperature. A correction method based on the lamp voltage is proposed to suppress the temperature dependence [11]. The method's concept is, at the same forward current, the change of lamp voltage reflects the change of junction temperature, which influences the luminous intensity performance.…”

“…National Institute of Metrology, China (NIM) is developing LED reference lamps with LED filament technique, to imitate traditional incandescent lamps [10]. Our previous work reports a prototype LED reference lamp for total luminous flux (LED-TLF) [11]. The ageing effect in the stability test of LED-TLF is estimated to be less than 0.1%/210 h, and the temperature dependence is suppressed to be less than 0.1% in the range of 21 ± 2 • C.…”

Recent advances and perspectives in photometry in the era of LED lighting

“…Practical LED light sources [18][19][20], with spectral irradiance resembling the L41 spectrum, have been developed. Even if their spectra would somewhat deviate from the reference spectrum L41, they would reduce the spectral mismatch error in photometer calibration relative to calibrations using incandescent lamps.…”

“…Even if their spectra would somewhat deviate from the reference spectrum L41, they would reduce the spectral mismatch error in photometer calibration relative to calibrations using incandescent lamps. The LED light sources [18][19][20] have also other promising features, such as robustness and stability, which make them attractive as complementary standard lamps, working standards, and comparison artefacts. Their performance will be tested in a forthcoming international comparison measurement with global coverage of participants.…”