Led Filament Standard Lamps for Total Luminous Flux and Luminous Intensity

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.

Section: Application Of K V In 210-day Stability Testmentioning

confidence: 99%

“…People can easily design and buy LED lamps due to the rapidly developing industry. In addition, to use them as the complementary standard [7]. Since NIM's prototype LED for total luminous flux standard (LED-TLF) mimics the 4π incandescent standard lamp, there is no space for an active temperature control component.…”

Section: Introductionmentioning

confidence: 99%

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

Zhao¹,

Yan²,

Liu³

et al. 2021

“…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].…”

Section: Introductionmentioning

confidence: 99%

Characterization of the LED filament lamp for luminous intensity calibration

Zhao

Yan²,

Liu³

et al. 2023

Light-emitting diode (LED) is now the main type of light source in global lighting marketing. However, traditional photometry with incandescent standard lamp is not sufficient to implement high level LED photometric measurement since a considerable spectral mismatch error may exist if the photometer has a large general V(λ) mismatch index . LED standard lamp is proposed to be the complementary transfer standard for photometry to reduce this measurement uncertainty. National Institute of Metrology, China (NIM) has previously reported a type of LED filament lamp for total luminous flux. In this article, NIM demonstrates another type of LED filament lamp for luminous intensity calibration. The LED filaments are sealed in T90 cylinder glass bulb as emitters, and has a spectrum similar to the reference white LED spectrum considered in Commission on Illumination (CIE) technical committee 2-90. The LED lamp uses the E27 screw base as the connector, and is compatible with the traditional alignment approaches. The warm-up time is less than 12 minutes. The output change of a group of 12 lamps, over a nearly two years of storage and 1 hour operation every day during the whole long term test, is found to be ±0.2 % or less for most of the lamps. The ageing effect of one lamp over a continuously 6500 hours burning is estimated to be -0.014% per hundred hours, and it is significantly lower than 1% per hundred hours, the typical drift rate of traditional incandescent luminous intensity lamp. In the aspect of the coincidence with inverse square law, the LED lamp has a similar performance to the WI41/G lamp, the traditional luminous intensity lamp.

“…Other commercial white LEDs that use a violet LED die to extend the wavelength range to the shorter end of the visible wavelengths also engender significant large uncertainties associated with wavelength calibration uncertainty and bandpass function effect around the violet peak. Some reports have described the development of new LED sources as a transfer standard or a numerically determined LED illuminant spectrum [12][13][14][15]. However, few reports have described studies examining LED source development as a transfer standard with emphasis on extending the spectral range of the spectrum [16].…”

Section: Introductionmentioning

confidence: 99%

Establishment of 2π total spectral radiant flux scale with a broadband LED-based transfer standard source

Nakazawa¹,

Godo²,

Niwa³

et al. 2020

The National Metrology Institute of Japan realized a total spectral radiant flux scale in the visible wavelength range (from 380 nm to 780 nm) for sphere-spectroradiometer calibration in 2π geometry. For a transfer standard in 2π geometry, a standard source based on a specially-designed broadband light-emitting diode (2π standard LED) was used. For the scale realization, we used the goniophotometer/spectroradiometer system. In the realization, an effect of a bandpass function of the array spectroradiometer was corrected by a matrix inversion approach. The relative expanded uncertainty (k = 2) for the scale is from 3.3% to 5.7% depending on the wavelength range. We also evaluated the contributions of the wavelength calibration and the bandpass function to the measurement of the total spectral radiant flux of typical white LEDs against the 2π standard LED. Our results demonstrate that the 2π standard LED achieves uncertainties comparable to those of a conventional standard lamp, within a practical wavelength range for LED measurements. These results show that the 2π standard LED is a useful transfer standard for the realization of the total spectral radiant flux scale and for evaluation of the total luminous flux of LEDs in 2π geometry.