International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395-0056
Volume: 04 Issue: 07 | July -2017
p-ISSN: 2395-0072
www.irjet.net
Spectroscopic studies of commercial LED lights & the emerging danger of “Blue-Light Hazard” Aman Nagi1, SK Gupta2, R. Manohar1,Atul Srivastava1# 1Uniersity
2Indian
of Lucknow, Lucknow,India. 226007 Institute of Technology, New Delhi,India. 110016
---------------------------------------------------------------------***--------------------------------------------------------------------Abstract - - This paper was formed to put some light on the hazardous effect of commercial LED bulbs by performing the spectroscopic measurements. This paper is putting light in the path for harmless lighting system. Key Words: Spectroscopy, LED (light emitting diode) 1. INTRODUCTION LED devices have set a new trend in the technology market today, their use is increasing exponentially because they are easy to manufacture, cost effective and power efficient. Use of LEDs can be seen from the balcony bulb of a ban glow to the bulb on a street vendor’s vegetable cart, wrist watches and mobile phones etc. [1,2,3] White light, with color temperature around 5000 K, is preferred especially in Asian countries over conventional incandescent lamps. This is the reason for surge in commercial value for white LED’s. White LED Bulbs are also available in many shades, from cool white (5500 K and higher) and warm white day light (2700 K to 3500 K) range. It is a known fact that by the use of different materials such as GaAs, GaP, GaAsP etc white light can be obtained[4,5].These white LEDs bulbs have many advantages but they suffer from some critical problems. In cool white LEDs, substantial amount of energy is present in blue region of spectra ie, wavelengths between 400-500 nm. This is known as blue hazard whereas in daylight LEDs wavelengths in blue region are very feebly present. “Bluelight hazard” causes retinal injury created by photochemical reaction by electromagnetic exposure of radiation at wavelength between 400-500 nm[6]. A permanent damage to pigment epithelial cells of retina may be caused by the continuous exposure of LED light of shorter blue band spectrum. Moreover longer use of such devices may cause fatigue in eyes and create skin problems [7,8,9].
Spectroscopic studies are carried out with the help of Avant’s Ava Spec- 2048 spectrometer for obtaining the emission spectra of different LED bulbs. Since UV scatter more than visible light, emission spectra of these LED bulbs at far field has also been obtained. Optical power measurements were performed by the help of Benchmark FO power meter at different supply voltages to find out intensity variations in light output with variations in supply voltage. 3. RESULTS AND DISCUSSION The lamp specifications mentioned on the packaging include its power ratings, given in watts, indicating total amount of electrical power consumed by the bulb, total amount of visible light emitted by bulb i.e. its luminous flux given in lumen and color of emitted light in color temperature. The total electric power consumption and luminous flux of all the three bulbs is evaluated and is tabulated in table 1,row 1,2&3, respectively against the values marked on the packaging. It is evident from the table 1 that unbranded bulbs (ie. Bulbs B & C) are not performing as per specifications provided on the packaging. The bulbs B & C are consuming greater power than the specified values and are also less efficient as compared to bulb A. Table -1 S.N o
2. EXPERIMENAL DETAILS
1
A quick survey of local market revealed that 7 watt , 6000K LED bulb has largest market share in LED bulb sale, so accordingly, we have taken 7 watt, 6500K bulb of a popular brand (Bulb-A), a 7 watt, 6500K unbranded bulb (Bulb-B) and an 12 volt,7 watt LED strip , unbranded, popularly used by street vendors (Bulb-C).
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PARAMETE R Electric Power Colour Temperatur e Luminous Flux
SPECIFIE D VALUE BULB A, B &C 7 watt
ESTIMETED VALUE
6500K 600 lumen
ISO 9001:2008 Certified Journal
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BULB –A 7 watt -
BULB –B 8.2 watt -
BULB C 8 watt
600 lume n
575 lumen
450 lumen
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