INCREASING THE LEVEL OF PHOTO BIOLOGICAL SAFETY OF THE EMISSION SPECTRUM OF AN LED LIGHT SOURCE

Abstract

The subject of research is the emission spectra of light sources based on LED structures. The purpose of the work is to formulate proposals to improve the photo biological safety of LED lighting systems. The article solves the following tasks: analyzing the situation in the field of photo biological safety of light sources based on LED structures, proposing a concept for improving it in sources based on LED modules with a two-component phosphor. Methods such as comparative analysis, spectrometric method are used. The following results were obtained. A brief analysis of the factors affecting the photo biological safety of artificial light sources based on LED modules and a review of modern technological developments aimed at improving it is carried out.  Since the implementation of these developments has a limited volume in the structure of the production of LED modules and a high cost, the concept of increasing the photo biological safety of light sources using cheap white light modules with a two-component phosphor and additional color modules to fill the gap in the spectral characteristic of white light has been proposed. A simple criterion is proposed for calculating the required ratio of white and color modules based on their spectral characteristics to activate the natural mechanism of eye protection due to pupil constriction. The work investigated color modules at wavelengths 480 nm, 492 nm and 503 nm. It has been shown that color modules with a shorter peak wavelength are needed less in relation to the number of whites to create a safe emission spectrum. The paper also estimated the fraction of the emission power with a wavelength of less than 450 nm in the emission spectra of the three investigated variants of combinations of white and color modules and four SunLike modules with different color temperatures. The share of the blue part of the spectrum in the emission power distribution of SunLike LED modules turned out to be higher than in traditional modules with a two-component phosphor at similar color temperatures. Conclusions. The proposed method increases the photo biological safety of the spectrum of LED light sources to the level of natural illumination due to adequate regulation of the pupil diameter and does not increase the total fraction of the emission power in the region λ ≤ 450 nm, which is dangerous for vision. This fraction is even less than in SunLike modules at close values of color temperature, since their emission spectrum is expanded to the region of shorter wavelengths and starts from λ ≈ 370 nm). Considering that the CVC characteristics of color and white LEDs are close, but not identical, their series connection leads to a redistribution of the emission power. In addition, LEDs from different manufacturers differ in energy efficiency and electrical parameters, therefore calculations in practice need to be adjusted in each specific case.