[Source: "High-tech LED - Technology and Applications" January issue Chen Yayong]


Lighting is a comprehensive interdisciplinary project combining technology with art, aesthetics, physiology, psychology, and human factors engineering. Historically, international standards such as CIE and IEC are developing with light source and visual cognition (including non-visual perception). And developed. At the same time, standards are the product of technological advancement and social practice. The colorful LED light source is driving innovation in photometry, colorimetry, color science and metrology, leading to changes in lighting concepts and light culture. In recent years, foreign lighting research institutions have proposed the light source illumination quality evaluation method of color quality CQS, color gamut GA and full color gamut index GAI based on the traditional color rendering index CRI.

How to make use of LED high color saturation, adjustable color light, multi-spectral combination and other characteristics, to show the charm of LED light source, become a new hot spot and new highlights of future lighting. Based on the review of various color rendering index evaluation indicators, this paper uses experimental verification and software simulation to construct a model of fluorescent film for white LED packaging, and simulates the spectral combination, which is used in the field of LED packaging.

First, CRI evaluation of LED light source color rendering caused international attention

For more than 40 years, European and American companies have used the color rendering index CRI to evaluate the quality of lighting sources. When LEDs have not entered the functional lighting field as widely as they are now, CRI has a positive significance in evaluating the light quality of traditional light sources. But today, the white LED visual effect is inconsistent with the measured CRI value. For example, when some RGB three primary colors are mixed into a white LED illumination object, the visual effect is good, but the CRI is less than 30 (3500K). Moreover, the wavelength shift causes a large difference in the color rendering index, and the human eye observation is completely incapable of discriminating the difference. In 2007, CIE Technical Report TC1-62, 177-2007 clearly stated: "In a series of light source comparisons, the technical committee concluded that CIE's CRI is not suitable for evaluating the color rendering range of white LEDs." This suggests that it is not appropriate to calibrate the quality of white LEDs along with the CRI color rendering index.

The CIE recommended method for quantitatively evaluating the color rendering of light sources is the “color measurement method” revised in 1974. CRI is not applicable to the fundamental problem of evaluating the color rendering of white LEDs.

1. Selection of standard illuminators

When the correlated color temperature (CCT) of the light source to be tested is lower than 5000K, the black body radiation is used as the reference illuminating body, and the correlated color temperature of the light source to be tested is higher than 5000K, and the recombined sunlight is used as the reference illuminating body. Whether blackbody radiation or recombination daylight is used as the reference illuminator, the spectrum is continuous spectrum, and most of the current white LED sources have enhanced monochromatic spectra.

For more information, please refer to the January issue of "High-tech LED-Technology and Applications" magazine.

The main circuit of the equipment is the full bridge controlled circuit and the trigger circuit is the programmable integrated circuit. The phase-shifting, fixed width and modulation of the pulse are all digitized, and it does not need any adjustment for the section of the trigger. It has the features of high reliability, high pulse symmetry, strong anti-interference ability, quick reaction, as well as the advantages of no heat-generating, constant current, energy-saving which is compared with the discharge with the electrical resistance.

AGV Battery Maintenance System

48 Volt Battery Charger,Low Maintenance Agv Battery Charger,Agv Portable Charger Discharger,Agv Battery Maintenance System

Xinxiang Taihang Jiaxin Electric Tech Co., Ltd , https://www.chargers.be