Evaluation On Photobiological Safety Of LED Ligit Sources For Children

With the rapid development of LED Technology, it has the advantages of long life, small size, high brightness, and low energy consumption, etc. and it has shown the development trend of high efficiency, high power, and high light flux, and has been widely used in daily life including children's toys and children's desk lamp. The light radiation of LED light source will cause photo-chemical hazard to the retina, and may cause amphiblestritis, then causing irreversible hazard to the retina of the human eyes. The evaluation of the photobiological safety of the light source has been concerned by the industry, the general public and the research institutions, and it has become a very important research topic. While there has GB/T 20145-2006 ?lamp and the lamp system light biological safety? (IDT CIE S009) and other domestic and international standards for the photobiological safety of LED light source can be implemented, however, in the standards the classification of the photobiological hazards, exposure limit, test conditions and methods are mainly derived from the guideline of The International Commission for Non-Ionizing Radiation Protection (ICNIRP), and the evaluation conditions and parameters in the guideline are set for the adults. At present, there is not yet a special evaluation method for LED light source for children.This paper is based on incorporating the optical properties of the physiological structure of children's eyes (mainly average spectral transmittance), the most in worst observing distance (focus near point of children's eyes), and differences in psychological and behavioral characteristics when children observing light source into photo-biological safety evaluation of LED light source for children, and has a research on the evaluation method of the blue light hazard of the light source. Firstly,there are differences between children and adults in the light of the optical properties (average transmittance and refractive power of the eye). On the other hand, children have stronger curiosity in the psychological characteristics more than the adults and lack of evasion and self-protection awareness when observing the light source, thus light source has great risk and harm for children. This objectively require that it can't simply use evaluation method in GB/T 20145when carrying out photo-biological safety evaluation for children, however it should incorporate the differences into evaluation method, and proposed a more suitable photo-biological safety evaluation of LED light source for children.Through the contrast experiment and analysis by selecting typical LED light source, this paper demonstrated that it has influence on safety classification results of the same light source when incorporating the difference between children and adult into blue light hazard and retinal thermal damage of photobiological safety evaluation, and it has further explained that it is necessary to carry out the different photo-biological safety evaluation for the LED light sources,when the application objects of the light source are different. Contrast test and analysis under different conditions shows that the most unfavorable distance caused by children eyes' focusing ability and psychological characteristics has great influence on photo-biological safety evaluation of LED light source for children, and may leads to consider the evaluation for adult is no risk, thus the insecurity and risk for children will increase significantly. From the comparative test of the influencing factors, it can be seen that the difference of the eyes' average transmittance between adults and children has little effect on photo-biological safety evaluation.This paper bases on optical radiation safety evaluation method for adults, combines with the difference in the psychological and behavioral characteristics and eye optical properties between children and adults as correction factor and set evaluation test conditions, and carries out comparative test and analysis, then promotes a more suitable photo-biological safety evaluation of LED light source for children.