JOURNAL OF THE ILLUMINATING ENGINEERING INSTITUTE OF JAPAN
Online ISSN : 1349-838X
Print ISSN : 0019-2341
ISSN-L : 0019-2341
Volume 83 , Issue 5
Showing 1-10 articles out of 10 articles from the selected issue
  • Shinichi Iso, Tatsushi Igarashi, Hiromitsu Matsuno
    1999 Volume 83 Issue 5 Pages 273-277
    Published: May 01, 1999
    Released: July 19, 2011
    JOURNALS FREE ACCESS
    UV/O3 cleaning by an Xe2*excimer lamp was investigated under various experimental conditions. We found that UV/O3 cleaning was caused by excited atomic oxygen {O (1D)} and that the cleaning speed was about six times faster than that using a low-pressure Hg lamp.
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  • Yoshinori Tanabe, Shiro Otake
    1999 Volume 83 Issue 5 Pages 278-287
    Published: May 01, 1999
    Released: July 19, 2011
    JOURNALS FREE ACCESS
    The recommended illuminance in the Japanese lighting standard (JIS Z 9110) was determined based on Indow and Kawai's experimental study concerning the relationship between illuminance and readability of printed text. As the observers in the experiment were young, the recommended illuminance derived from the experiment cannot be applied directly to older people. To estimate the recommended illuminance for older people, a set of numerical analyses wasconducted. We found that the readability scale in the above experimental study correlates with the Visibility Level (VL) defined by CIE publication No.19/21. The luminance difference threshold (ΔLmin) derived from the contrast threshold function (Cth) of the CIE publication was divided into two parts (ΔLaf for foveal adaptation and ΔLeq for veiling luminance), assuming ΔLmin=ΔLaf+ΔLeq. After considering age factors in each part, the luminance difference threshold function ΔLmin*was reconstructed. Applying the ΔLmin* function to the VL analysis, the recommended illuminance for older people was estimated. The result shows that at least about 700 lx of illuminance may be recommended for older people reading 3-mm high printed characters. The visibility level analysis is a useful method for assessing readability considering age-related effects.
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  • Yoko Mizokami, Mitsuo Ikeda, Hiroyuki Shinoda
    1999 Volume 83 Issue 5 Pages 288-294
    Published: May 01, 1999
    Released: July 19, 2011
    JOURNALS FREE ACCESS
    The size of the recognized visual space of illumination (RVSI) is a concept for expressing the perception of brightness of a space recognized by an observer. If he/she recognizes the space as being brightly illuminated, the size of RVSI is said to be large. The apparent lightness of an object placed in the space is determined relative to the size of the RVSI. The size is controlled by changing the illumination level of the space. It can also be controlled by changing the lightness of the interior of the space even if the illumination is kept constant. Then the apparent lightness of the object becomes lower with an interior having high lightness. Two miniature rooms in the depth direction from a subject, were illuminated at the same illuminance level, but the front room had walls, floors and furniture with lowerlightness than the back room. It was expected that the RVSI of the front room would be smaller in size than that of the back room. The two rooms were separated by a partition frame projecting from the side walls. In this paper the effect of the projection size of the partition on the size change of RVSI at the boundary of the two rooms was investigated by measuring the apparent lightness of a test patch along the depth of the rooms for three different projection sizes. It was found that the effect of projection size was not significant and the separation into two RVSIs was mainly achieved by interior lightness.
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  • Taiichiro Ishida, Yasuo Ogiuchi
    1999 Volume 83 Issue 5 Pages 295-305
    Published: May 01, 1999
    Released: July 19, 2011
    JOURNALS FREE ACCESS
    This study examined a method for evaluating the brightness of a space using a reference space as a standard for judging brightness. Subjects observed the test and reference spaces, and made brightness match by adjusting illuminance of the reference space. Matching was carried out for a model box with three different conditions (Exp.1) and a full-sized room (Exp.2) under a wide range of illuminance. Brightness matches made for each of the test spaces were consistent within one subject and among all subjects. The relationship between illuminance of the reference space and that of the test space at equivalent brightness was found to be linear on a logarithmic scale. These results suggest that the reference matching method is useful for evaluating the brightness of a space. Some problems with this method are also discussed.
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  • Takayuki Hisamune, Masakazu Nabu, Akihiro Ohto, Yasuo Oguri, Tadashi E ...
    1999 Volume 83 Issue 5 Pages 306-313
    Published: May 01, 1999
    Released: July 19, 2011
    JOURNALS FREE ACCESS
    BaAl12O19 is considered to be a mixture of a Ba-poor aluminate (0.82 BaO·6 Al2O3) and a Ba-rich aluminate (xBaO·6Al2O3, x=1.30±0.2). Because the Ba-poor aluminate and BaMgA110O17 (BAM) have exactly the same crystal structure as β-alumina, both compounds form solid solutions with it. In this study, we prepared various kinds of solid solutions of the Ba-poor aluminate and BAM in which Mn2+ was substituted for some or all of the Mg2+. These formulae can be expressed as (1-α) (0.82BaO·6Al2O3)·α (BaMg1-βMnβAl10O17). Their emission properties under 146 nm excitation were studied. As α and β were changed with a constant Mn2+ content in the phosphor (α·β=0.12), two kinds of bright solid solutions were found. One was a BAM-poor solid solution (α=0.12, β=1.0) and the other was a BAM-rich solid solution (α=0.92, β=0.13). Substituting Sr2+ for Ba2+ improved the luminance of the BAM-rich solid solution. For example, the composition of a BAM-rich solid solution in which Sr2+ replaced 76% of the Ba2+ was Ba0.24Sr0.75Mg0.80Mn0.12A110.2O17.21. Comparing the properties of this phosphor with those of the conventional BaAl12O19: Mn, we found the luminance was 18% higher, the chromaticity was purer green (x=0.146, y=0.749) and the 1/10 decay time was equivalent (14 ms). This material should serve as a new green phosphor for PDPs, though its lifetime in PDPs remains to be measured.
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  • Maiko Katano, Masako Saito, Kohtaro Kohmoto
    1999 Volume 83 Issue 5 Pages 314-319
    Published: May 01, 1999
    Released: July 19, 2011
    JOURNALS FREE ACCESS
    The effect of the light sources for art galleries and museums on fade-prevention of fabrics containing natural dyes was investigated. 11 fabrics dyed with four kinds of main colorants and five kinds of mordants, which are often used in textile properties and the Blue Scale were used as test samples. The light sources were the fluorescent lamp type D65 daylight illuminant simulator, the conventional cool white fluorescent lamp for general illumination, and the fluorescent lamp for art galleries and museums, which is designed to reduce fading by cutting the ultraviolet radiation. Under controlled temperature (29±1°C) and relative humidity (59±2 %), exposure was continued for 700 hours. Then the color difference (ΔE) of each sample was calculated.
    Discoloration of the Blue Scale was recognized for the scale less than 3rd grade for all the lamps, but ΔE did not exceed 2. Comparing the grade of the discoloration of the dyed fabrics with that of the Blue Scale, curcumin/iron (III) acetate, quercetin, heamatoxylin, and carminic acid were equivalent to the 2nd grade, and curcumin/hydrated lime, alumstone, and ash were equivalent to the 1st grade for each lamp. From the comparison of ΔE of the dyed fabrics between the lamps, the average effect on fade-prevention for lamp for art galleries and museums was 28% compared with lamp type D65, and 30% compared with the white lamp. The maximum fade-prevention effect was 50% for curcumin/iron (III) acetate.
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  • Hidenori Kakehashi, Hiroshi Ogasawara, Tamotsu Ninomiya
    1999 Volume 83 Issue 5 Pages 320-325
    Published: May 01, 1999
    Released: July 19, 2011
    JOURNALS FREE ACCESS
    A transformer-type ignitor for instantaneous restarting of a High Intensity Discharge (HID) lamp was investigated. High-voltage pulses are required to instantaneously restart the HID lamp at high temperature, and obtaining such high-voltage pulses requires a special switch with high voltage and heavy current ratings on the primary side of the pulse transformer. However, conventional semiconductor switches in general use cannot meet such high ratings.
    This paper proposes an HID-lamp ignitor using a magnetic switch instead of the semiconductor one, and analyzes its operating characteristics. From analytical results, the optimum design of circuit parameters was derived. A breadboard was implemented to confirm the analysis and design procedure experimentally. Output-voltage pulses of about 10kV were successfully obtained from the input voltage of AC 200V.
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  • Mitsuyuki Kawakami, Shuichi Matsumoto, Osamu Myodo
    1999 Volume 83 Issue 5 Pages 326-331
    Published: May 01, 1999
    Released: July 19, 2011
    JOURNALS FREE ACCESS
    This paper presents a proposal to design factors for a reasonable lighting environment in Visual Display Terminal (VDT) work, by monitoring changes in the lighting environment by general illumination and partial illumination as a factor of the working environment. We also considered that this factor affects productivity and workload from an experimental approach. Since we think that it is not enough to evaluate a lighting environment only by subjective appraisal, we used brain waves as a physiological index for evaluating human mental activity objectively. The evaluation indexes used in the experiment were obtained by measuring working efficiency and working quality in VDT work, mental changes (stability) recorded by an electroencephalograph (EEG), and determined the workload by a survey of subjective symptoms and by measuring eye fatigue.
    The results enabled us to derive a relationship between reasonable lighting environment and illuminance. The results show the following: 1) When the partial illumination was given to subjects, it was shown to effect their concentration on work and mentally stabilize at the ratio of surround illuminance to horizontal illuminance was about 0.05. 2) When the ratio of surround illuminance to horizontal illuminance was the same, the effect showed remarkable at the ratio of vertical illuminance to horizontal illuminance was lower.
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  • Minoru Myojo, Atuo Waki, Ikuhiro Okuno
    1999 Volume 83 Issue 5 Pages 332-342
    Published: May 01, 1999
    Released: July 19, 2011
    JOURNALS FREE ACCESS
    High-frequency fluorescent lamp operation requires proper cathode preheating by electronic ballasts incorporating a preheating function. This paper examines minimum thermionic emission curves for three different ways of measuring emission times. One is based on a lamp ignition test, another on the ratio of hot to cold coil resistance (Rh/Rc), and the third on lamp voltage monitoring. The observation that the emission time measured by the lamp ignition method tends to be shorter than that measured by the lamp voltage monitoring method in a short preheat time may be understood in terms of the relaxation of the limited thermal conductivity of the emissive material due to the initial flow of the discharge current. We do not believe that the shorter emission time measured by the lamp ignition method causes premature thermionic emission. The Rh/Rc method needs much more investigation to measure emission times because it depends on the resistance of the whole cathode composed of the filament coil and the emissive material, whose specific heats differ.
    This paper points out that the average resistance of a standardized cathode over the period up to the emission time should be regarded as a substitution resistor. Furthermore, the maximum preheating lines for the requirement in the present IEC should be changed into a maximum curve similar to the minimum thermionic emission curve.
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  • 1999 Volume 83 Issue 5 Pages 352
    Published: 1999
    Released: July 19, 2011
    JOURNALS FREE ACCESS
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