Journal of Light & Visual Environment
Online ISSN : 1349-8398
Print ISSN : 0387-8805
ISSN-L : 0387-8805
Volume 35, Issue 3
Displaying 1-17 of 17 articles from this issue
Papers
  • Masaru SASAKI
    2011 Volume 35 Issue 3 Pages 187-191
    Published: 2011
    Released on J-STAGE: March 07, 2012
    JOURNAL FREE ACCESS
    Automotive headlamps have been evolved with their light sources. From Tungsten-Halogen (TH) bulbs to High Intensity Discharge (HID) bulbs, and then Light Emitting Diode (LED) is now rising. The first LED headlamp was put in the market in 2007 and the second generation was released in 2009 to enhance the energy saving feature of LEDs. But LED headlamps are facing tough competition with HID when they made the evolution for removing mercury and then started to reduce their system cost and power consumption. This is a full paper that the author presented at the LS-WLED 2010.
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  • Kanji BAND
    2011 Volume 35 Issue 3 Pages 192-196
    Published: 2011
    Released on J-STAGE: March 07, 2012
    JOURNAL FREE ACCESS
    The performance of InGaN/YAG white LEDs for lighting applications is reviewed. Advanced small-chip-technology has achieved high-luminous efficacy white LED of almost 200lm/W by improving internal efficiency, extraction efficiency and electrical resistance. In addition, high-luminous flux device of 10,000lm by flip-chip array has been also developed by large-chip-technology.
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  • Boris KOLODIN, Glenn KUENZLER, Jiawei LEE, Peter BROWN, Anirudha DESHP ...
    2011 Volume 35 Issue 3 Pages 197-198
    Published: 2011
    Released on J-STAGE: March 07, 2012
    JOURNAL FREE ACCESS
    Proposed short pass filter (SPF) employment to improve efficiency of phosphor converted white LED based on near UV LED dies and remote RGB phosphor architecture. SPF is transparent for near UV radiation in the 390-430 nm spectral range and possesses high reflectance for visual spectral range. SPF is placed between near UV LED and phosphor layer and redirects part of down warding white light to the outside of the package. Demonstrated 26 % average improvements for the conversion efficiency from 10.9 to 8.0 mW/Lm and 24 % average increase for luminous efficacy for 3000°K CCT and 85 CRI.
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  • Arno KEPPENS, Paula ACUÑA, Huanting CHEN, Geert DECONINCK, Pete ...
    2011 Volume 35 Issue 3 Pages 199-206
    Published: 2011
    Released on J-STAGE: March 07, 2012
    JOURNAL FREE ACCESS
    High-power light-emitting diode (LED) efficiencies are strongly dependent on device type and operating conditions. Electrical and optical power measurements are performed on five commercially available phosphor-white LED types for a number of independently enforced forward currents and junction temperatures. The experimental results allow for a comparative evaluation of dominant loss mechanisms and their current and temperature dependences.
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  • Kazuaki YAMAGUCHI, Hubertus T. HINTZEN, Anne C. A. DELSING, Hideki KUW ...
    2011 Volume 35 Issue 3 Pages 207-213
    Published: 2011
    Released on J-STAGE: March 07, 2012
    JOURNAL FREE ACCESS
    The conditions for the preparation of regular-shaped Eu2+-doped calcium silicon nitride ((Ca0.99Eu0.01)2Si5N8) powder were examined by the carbothermal reduction and nitridation (CRN) of oxide/nitride powder prepared by ultrasonic spray pyrolysis. Two kinds of silicon sources, i.e., (i) colloidal silica (CS) and (ii) silicon nitride (Si3N4; SN), were used for the spray pyrolysis. Firstly, the solution containing 0.057 mol·m-3 Ca(NO3)2, 0.140 mol·dm-3CS and 5.71 x 10-4 mol·dm-3Eu(NO3)3 was spray-pyrolyzed at 600°C, and the resulting powder was calcined at 800°C for 10 min in air. The single phase but agglomerated particles of (Ca0.99Eu0.01)2Si5N8 were obtained when the CRN (the relative carbon amount to the stoichiometric amount (m): 1.5) of spray-pyrolyzed/calcined oxide powder was conducted at 1300°C for 2 h in nitrogen (N2) atmosphere. Secondly, the solution containing 0.0285 mol·dm-3Ca(NO3)2, 0.070 mol·dm-3SN and 2.855 x 10-4mol·dm-3Eu(NO3)3 (one-half of the solution concentration compared to the case of CS utilization) was spray-pyrolyzed, and the CRN of spray-pyrolyzed oxide/nitride powder was conducted at 1500°C for 2 h to obtain (Ca0.99Eu0.01)2Si5N8 in N2 atmosphere. The microscopic observation showed that this powder was composed of regular-shaped particles with sizes of approximately 2-3 μm. The excitation and emission peaks of this powder appeared at around 370 and 590 nm, respectively, showing the emission of orange light.
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  • Cadmus YUAN, Müge ERINC, Sander GIELEN, Adri van der WAAL, Willem ...
    2011 Volume 35 Issue 3 Pages 214-221
    Published: 2011
    Released on J-STAGE: March 07, 2012
    JOURNAL FREE ACCESS
    Lighting is an advancing phenomenon both on the technology and on the market level due to the rapid development of the solid state lighting technology. The efforts in improving the efficacy of high brightness LED's (HB-LED) have concentrated on the packaging architecture. Packaging plays a significant role in reliability; not only on mechanical protection but also on thermal management. An efficient numerical model using the finite element technique to evaluate thermal and mechanical performance of LED packaging is presented in this article. A commercial HB-LED package is used as a benchmark example and a strategy relying on the obtained thermo-mechanical response to reduce the mesh size and density is proposed. Next, two new HB-LED concepts are simulated based on the proposed finite element modeling strategy.
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  • Ray GIBSON
    2011 Volume 35 Issue 3 Pages 222-226
    Published: 2011
    Released on J-STAGE: March 07, 2012
    JOURNAL FREE ACCESS
    A continual challenge in lamp development is the need to rapidly test products that have lifetime ratings in the tens of thousands of hours. Traditional life testing, under controlled conditions, remains a mainstay test procedure. However, highly reliable statistical analysis methods allow lamp developers to estimate long lifetimes at a fraction of the testing time. These techniques usually involve the well known Weibull distribution together with historic data, multi-level accelerated stress testing, and virtual failure analysis to reduce the necessary testing times for establishing product life and reliability.
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  • Victor TARASENKO, Mikhail EROFEEV, Mikhael LOMAEV, Dmitry RYBKA, Alexe ...
    2011 Volume 35 Issue 3 Pages 227-233
    Published: 2011
    Released on J-STAGE: March 07, 2012
    JOURNAL FREE ACCESS
    Design and output parameters of pulse sources of spontaneous UV and VUV radiation based on the non-equilibrium discharge plasma of high-pressures gases are presented in this paper. Emission characteristics of plasma of diffuse discharge preionized by runaway electrons and barrier discharge in rare gases and mixtures of rare gases with halogens have been investigated in gases at pressure up to 15 atm at excitation power up to 100 MW/cm3. The radiant power from 4π solid angle up to 1.2 MW with pulse duration of - 8 ns on Xe2* dimers were obtained at 12 atm pressure xenon. A high-voltage (up to 150 kV) short pulsed excitation mode was tested on dielectric barrier discharge KrCl- and XeBr-excilamps.
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  • D.Gordon KNIGHT, Ronald KILGOUR
    2011 Volume 35 Issue 3 Pages 234-240
    Published: 2011
    Released on J-STAGE: March 07, 2012
    JOURNAL FREE ACCESS
    Low pressure mercury arc lamps are an effective ultraviolet light source for disinfection of water. Critical lamp operating parameters such as the decrease in UV output with time, effect of water temperature on lamp output, and the effect of lamp dimming should be determined using a lamp in water. The reliable operation of a near-field test apparatus is described that is capable of measuring these quantities. The use of a radiometer with fiber optic light collection and standard reference lamp results in the reproducible measurement of these values using the near-field system. The stability of measurement is obtained using the reference lamp, which compensates for variations in the response of the fiber optic assembly. For sample lamps, a decrease of 11% output over 12,000 hours was observed. For the same lamp type, the relative calibrated output of the lamp increases between 5 and 50°C, with a ±10% change in lamp output relative to the reference temperature of 20°C. The apparatus samples the irradiance at a local point on the lamp, but the UV output of low pressure amalgam lamps as determined by the near-field technique is shown to be uniform over the entire lamp, except for within 1 cm of the lamp filament. This is shown for both new and 12,000 hour aged lamps, so that accurate lamp aging data can be determined. The change in UV output with water temperature change was demonstrated to be similar for both new and aged lamps in this study, except for the expected decrease in peak lamp UV output noted for the aged lamp.
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  • Mykola M GUIVAN, Antonin BRABLEC, Pavel ST'AHEL, Pavel LAVÍCEK, ...
    2011 Volume 35 Issue 3 Pages 241-244
    Published: 2011
    Released on J-STAGE: March 07, 2012
    JOURNAL FREE ACCESS
    In this contribution to the research, electrical, optical, as well as energetic properties of the coplanar surface barrier discharge (CSBD) operated with the Xe/I2 and Kr/Xe/I2 mixtures at pressures of p (Xe)≤ 50 kPa and p (Kr/Xe) = 10 - 100 kPa are presented. Varying the gas composition, pressure and pump pulse repetition rate makes it possible to control the discharge pattern and achieve a diffuse discharge or completely filamentary CSBD. The optimal UV output was obtained using Xe/I2 = 20/0.04 kPa and Kr/Xe/I2 = 46/4/0.04 kPa mixtures. The krypton admixture enhances the Xel(B-X) emission for about 15% in comparison with a binary Xe/I2 mixture. The average radiation power and efficiency of 8 mW/cm2 and 3% were measured at a frequency of 100 kHz.
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  • Tadao UETSUKI, Akira MATSUO, Katsuyuki MORII, Hisao HATANAKA
    2011 Volume 35 Issue 3 Pages 245-249
    Published: 2011
    Released on J-STAGE: March 07, 2012
    JOURNAL FREE ACCESS
    Thoriated-tungsten (ThO2-W) is popularly used for the electrodes of a super-high pressure mercury lamp, or for arcwelding, because of its excellent performance as to the electron emission. Because it is radioactive, however, a new material which can replace it would be desirable. To find a material to replace ThO2W as the electrode, we have made many kinds of electrodes by a new process, which is different from the traditional process, and evaluated their performance. We have found that neodymium oxide or samarium oxide made by the new process produces encouraging results.
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  • Mark S. REA
    2011 Volume 35 Issue 3 Pages 250-254
    Published: 2011
    Released on J-STAGE: March 07, 2012
    JOURNAL FREE ACCESS
    Light is formally defined in terms of the photopic luminous efficiency function [V(λ)], but the spectral sensitivity of the human circadian system is poorly characterized by this spectral weighting function. A new definition of circadian light should be considered because of the impact that fabricated and natural light sources may have on human health and well-being. Establishment of a formal definition of circadian light could lay the foundation for a new generation of lighting professionals and better lighting standards.
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  • Maria THOMPSON, Joseph LASKI, Makarand CHIPALKATTI
    2011 Volume 35 Issue 3 Pages 255-266
    Published: 2011
    Released on J-STAGE: March 07, 2012
    JOURNAL FREE ACCESS
    Digitally controlled lighting systems equipped with colored LEDs can produce a range of different qualities of light, adjustable to users' requirements. In this context, we explore a lighting control concept which involves strategic control of RYGB LEDs forming white light, employed to increase energy efficiency. There is a fundamental trade-off between color rendering (CR) and luminous efficacy. Specifically, we can reduce CR and increase efficacy when we redistribute spectral energy intensity in favor of wavelengths where the eye response is greatest, the yellow/green region of the spectrum. The notable point is that while changing CR, the light level and color temperature can stay constant, and hence the appearance of the modified white light remains unchanged. The strategy is to bring the lighting of unoccupied spaces to minimum color rendering to save energy without altering the appearance or light levels of the illumination, when the LED system dynamically shifts to 'energy saving mode' (low CR) from 'quality mode' (high CR) according to occupancy. This paper reports and discusses the results of an ongoing research project involving the exercise of LED color mixing re-working the spectrum of white light according to this fundamental energy vs. rendering trade-off. The research work encompasses two main domains: (a) a tunable LED light source with accompanying control equipment; and (b) human factors studies concerning how surfaces and spaces are perceived under a light source with changing spectral components. Results so far have supported the two fundamental hypotheses: (a) when fully developed, color rendering modulation could potentially enable significant power reductions; (b) the majority of subjects did not detect the color rendering changes.
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Research Notes
  • Willem D. van DRIEL, Francis EVERTZ, G.Q., Kouchi, ZHANG
    2011 Volume 35 Issue 3 Pages 267-273
    Published: 2011
    Released on J-STAGE: March 07, 2012
    JOURNAL FREE ACCESS
    Solid State Lighting applications are slowly but gradually pervading into our daily life. A Solid State Lighting system is composed of a LED engine with a micro-electronic driver(s) in a housing that also supplies the optic design. Knowledge of system level reliability is crucial for the business success of future Solid State Lighting (SSL) systems, and also a very scientific challenge. In practice, a malfunction of the system might be induced by the failure and/or degradation of the subsystems/interfaces. Extra costs, in terms of exceed efforts/designs/parts, has been applied to the system in order to secure the guaranteed reliability performance of SSL system. The most SSL system designs allow few failures of the subsystem/interface during the application period. Hence, a significant cost reduction can be achieved when the system level reliability is well understood by proper experimental and simulation techniques. This paper will cover the reliability of total Solid State Lighting systems including the reliability theories and practices for all(sub-) components, such as LED engines, drivers and fixtures.
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  • Ruslan KOZAKOV, Heinz SCHOEPP
    2011 Volume 35 Issue 3 Pages 274-277
    Published: 2011
    Released on J-STAGE: March 07, 2012
    JOURNAL FREE ACCESS
    Novel findings in the chronobiology show that light plays an important role in the synchronization of the inner biological rhythms of a human with outer environment. Such synchronization is mediated by newly found light-sensitive receptors which don't contribute to the visual perception of light. The results of the ongoing research show that the correct prediction of the light induced melatonin suppression based on the measurements of spectral irradiance at cornea is possible. The correct account for major influence factors allows proposing the standard evaluation procedure for non-visual action of light.
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  • Technical and Social Approaches
    Michel AUBES, Julien BANCE, Sounil BHOSLE, Laurent MASSOL, Patricia SA ...
    2011 Volume 35 Issue 3 Pages 278-282
    Published: 2011
    Released on J-STAGE: March 07, 2012
    JOURNAL FREE ACCESS
    We report a global study of a LED lighting system for an urban roundabout (LED-VILLE). A study of the photometric performances of the LED used has been performed in our laboratory. Furthermore, average illuminance, uniformity and luminance have been measured and compared to recommended data. Environmental footprints of this lighting system (carbon operation, life cycle analysis and light pollution) has been evaluated and compared to equivalent solution widely used to date. Finally, a social approach of the LED street lighting has been achieved: the visual perception felt by driving or walking users through the roundabout have been collected and analyzed.
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