JOURNAL OF THE ILLUMINATING ENGINEERING INSTITUTE OF JAPAN
Online ISSN : 1349-838X
Print ISSN : 0019-2341
ISSN-L : 0019-2341
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Volume 92, Issue 8A
Displaying 1-5 of 5 articles from this issue
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Papers
  • Quantification of Perceived Whiteness
    Tetsuya Eda, Miyoshi Ayama
    2008 Volume 92 Issue 8A Pages 445-454
    Published: August 01, 2008
    Released on J-STAGE: October 14, 2008
    DOIhttps://doi.org/10.2150/jieij.92.445
    JOURNAL FREE ACCESS
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    In this study, we quantitatively expressed the change in perceived whiteness of whitish surfaces under 3000 K and 6700 K fluorescent lamps. The experimental results of the previous study plotted in the CIECAM02 (a, b) plane were well fitted by a bivariate normal distribution. Furthermore, we conducted the experiment to determine the relative values of perceived whiteness under these fluorescent lamps. The perceived whiteness of a reflectance standard under a pseudo-D65 fluorescent lamp was set to 100, and the results showed that the relative whiteness level was 74 and 89 under 3000 K and 6700 K lamp, respectively. We proposed a method to calculate the relative value of perceived whiteness of a certain whitish surface under any light source.
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  • Experiment to Evaluate Visibility of Street Luminaire with Different Upward Light Output Ratios and Use of Calculated Veiling Luminance to Determine Contrast Performance
    Michico Iwata, Shigemi Uchida
    2008 Volume 92 Issue 8A Pages 455-463
    Published: August 01, 2008
    Released on J-STAGE: October 14, 2008
    DOIhttps://doi.org/10.2150/jieij.92.455
    JOURNAL FREE ACCESS
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    The visibility of two luminaires was evaluated in the simulated street lighting system shown in Fig.1. One luminaire had an Upward Light Output Ratio (ULOR) of 12.6%, and the other had a zero ULOR. The visibility of pedestrians, colored objects, and the objects located out of the line of sight was evaluated, and an eye chart test was performed. To determine the contrast performance the veiling luminance (Lv) was calculated for the same lighting system and compared to the measured target luminance. We also investigated the effect of the different ULORs on older people. The results indicate that there are both advantages and disadvantages of the two ULORs and also show that the glare caused by the luminaire of the non-zero ULOR had an adverse effect.
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  • Effect of Operating Frequency on Plasma Characteristics of Inductively Coupled Electrode-less Lamp
    Tadao Uetsuki, Masahiro Ueda, Satoshi Nimata, Motohiro Saimi, Hidenori ...
    2008 Volume 92 Issue 8A Pages 464-471
    Published: August 01, 2008
    Released on J-STAGE: October 14, 2008
    DOIhttps://doi.org/10.2150/jieij.92.464
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    To increase the efficiency and lumen output of inductively coupled electrodeless lamps, numerous studies have attempted to reduce their operating frequency. This is because reducing the operating frequency enables a wide range of semiconductor devices to be used that in turn enable higher lumen outputs to be obtained from these lamps. The switching loss can be reduced thus increasing the efficiency. We investigated the relationship between the operating frequency of a 50-W electrodeless lamp and its characteristics. Operating frequencies of 13.56 MHz and 135 kHz were used. The characteristics that we investigated are its starting characteristics, the plasma characteristics (such as the temperature and density of the electrons), and its efficiency in producing UV radiation. The results show that the efficiency in producing UV radiation at 135 kHz is 7% lower than that at 13.56 MHz, and that plasmas generated at an operating frequencies of 135 kHz and 13.56 MHz had different electron-density and electron-temperature distributions because of the different power input positions.
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  • Improvement in Durability of Red Phosphor Encapsulated by Sol-Gel Glass for Use in White Light-Emitting Diode
    Eimo Kin, Takeshi Fukuda, Norihiko Kamata, Hidehiko Ohara, Toshiaki Yo ...
    2008 Volume 92 Issue 8A Pages 472-477
    Published: August 01, 2008
    Released on J-STAGE: October 14, 2008
    DOIhttps://doi.org/10.2150/jieij.92.472
    JOURNAL FREE ACCESS
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    Transparent glass films with homogeneously doped light emissive molecules can be prepared by using the sol-gel process. As part of our work on improving the durability of water-soluble polysilanes against UV light irradiation, we fabricated Eu(TTA)3Phen-doped sol-gel glasses and studied their optical characteristics. Using a three dimensional dense glass network protects the Eu complex from free oxygen and water in an ambient and also improves the durability without any loss of light output. By adding the Eu(TTA)3Phen beyond the limit of solubility in a starting solution, we demonstrated that the glass encapsulation prevents oxidation of the Eu-complex and also preserves its excitation intensity at a wavelength of 400 nm.
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