JOURNAL OF THE ILLUMINATING ENGINEERING INSTITUTE OF JAPAN
Online ISSN : 1349-838X
Print ISSN : 0019-2341
ISSN-L : 0019-2341
Volume 96, Issue 11
Displaying 1-5 of 5 articles from this issue
Original Papers
  • Harada Yoko, Haruhiko Yamamoto, Kiyoshi Iwaya, Nanae Kaneko, Yoshimits ...
    2012 Volume 96 Issue 11 Pages 733-738
    Published: November 01, 2012
    Released on J-STAGE: February 01, 2013
    JOURNAL FREE ACCESS
    In agriculture, particularly wet rice cultivation, light pollution caused by exterior illumination at night interferes with dark periods and results in delayed flowering (heading). In this study, using light emitting diodes (LEDs), which make it relatively easy to irradiate selective wavelengths and control luminescence, the effects on the heading of rice of the wavelength of the light source it was exposed to at night and the control of luminescence (pulse emission frequency and duty ratio) were investigated through the expression of floral activator Hd3a. The results indicated that, under illumination with blue or green LEDs, the effect on the delay of flowering was small, but under illumination with near ultraviolet, yellow or red LEDs, it was large. Under illumination with yellow-green LEDs, it was predicted that heading would be delayed when the duty ratio was 100 %; however, when the duty ratio was 70 % and the pulse emission frequency was 700 Hz, the effect on the delay of heading was small. Therefore, it was suggested that by selecting the wavelength of light sources that rice is exposed to and controlling luminescence, it is possible to bring the time of heading closer to that of total darkness (control plot).
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  • - Effects of Retinal Locus and Contrast -
    Qianying Dai, Yoshiki Nakamura
    2012 Volume 96 Issue 11 Pages 739-746
    Published: November 01, 2012
    Released on J-STAGE: February 01, 2013
    JOURNAL FREE ACCESS
    The purpose of this study was to consider the perceived brightness change in peripheral vision affected by retinal locus and contrast (peripheral field luminance/background luminance). Using the matching method and Nakamura's fovea brightness simulation system comprehensively, we complexly calculated the contrast change from the background, which cannot reflect in matching luminance, and significant perceived brightness changes among retinal loci were obtained. The result shows that the calculated peripheral brightness value in each contrast series is proportional to the luminance logarithm. Peripheral brightness is brighter than in the fovea when the contrast is larger than one and darker than in the fovea when the contrast is smaller than one. As a result, the calculated peripheral brightness value is greatly changed by the contrast effect further away from the fovea. Peripheral brightness is more sensitive to change by the contrast effect in smaller target stimuli. However, under low luminance conditions, peripheral brightness is brighter than in the fovea independent of contrast. These results show that the calculated peripheral brightness value's change in each retinal locus is based on equal contrast.
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  • Fumiaki Itou, Susumu Morimoto, Gen Hattori, Hidekazu Ito
    2012 Volume 96 Issue 11 Pages 747-751
    Published: November 01, 2012
    Released on J-STAGE: February 01, 2013
    JOURNAL FREE ACCESS
    The blood orange (Citrus sinensis) is one of the sweet orange cultivars, and its flesh color changes orange to purple. Anthocyanins impart the characteristic purple color of the flesh, and one of the primary anthocyanins is cyanidin-3-glucoside. The purple color is attractive and valuable to consumers, and the anthocyanins have antioxidants. However, it is difficult to judge this purple-colored flesh from the external appearance of the blood orange. Therefore, the objective of this study is to assess the potential of non-destructively determining the purple-colored flesh in blood oranges using visible (Vis) / near-infrared (NIR) spectroscopy. Multiple linear regression (MLR) analyses of the spectra (500 nm -1000 nm) of intact blood oranges (n = 48) gave a calibration equation that uses absorbance at 508 nm, 580 nm, 606 nm, and 834 nm with a multiple correlation coefficient of 0.87. The MLR calibration was validated by using other blood orange sample lots, and the intact blood oranges were predicted well. Therefore, VIS / NIR technology is a potentially effective way to non-destructively determine the purple color of the flesh in blood oranges.
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  • Keiko Nakagawa, Yukio Akashi, Takayuki Arimatsu, Nobuhiro Kyoto
    2012 Volume 96 Issue 11 Pages 752-760
    Published: November 01, 2012
    Released on J-STAGE: February 01, 2013
    JOURNAL FREE ACCESS
    The International Commission on Illumination (CIE) approved a compensated mesopic photometry system (MES2) to bridge between V (lambda) and V' (lambda). However, before the system is applied to real road lighting applications, several problems need to be solved. Among them, we investigated the effects of target positions on the Purkinje phenomenon and therefore on the current mesopic photometry system. We conducted two experiments by using a high-pressure sodium (HPS) lamp and three ceramic metal halide (CMH) lamps. The experimental results showed that there were small variations in the Purkinje effect depending on target positions. Such experimental results seemed to reflect retinal density distributions of cones and rods. Practically, however, mesopic luminances obtained from the CIE mesopic photometry system (MES2) were correlated to reaction times to targets presented at eccentricity angles between 5- and 15-degrees. The experimental results also suggested that a glare source appeared to exaggerate differences in reaction time for peripheral target detections between HPS and CMH illuminations, and therefore that the use of lamps with higher S/P ratios improved drivers' visual performance more than the mesopic photometry predicts.
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Research Note
  • Kazuaki Ohkubo, Shyunsuke Mishima
    2012 Volume 96 Issue 11 Pages 761-766
    Published: November 01, 2012
    Released on J-STAGE: February 01, 2013
    JOURNAL FREE ACCESS
    Integrating spheres are widely used to measure total luminous flux of LED light sources. Their detector heads are required to have a directional response matched to Lambert's cosine law on the principle of the integrating sphere. It is approved on IES-LM79, the measurement method provisions, that the directional response, f2, has a value less than 15 %. In practice, for cosine response a small integrating sphere (satellite integrating sphere) is used as a light receiving system of many sphere photometers. However, this also creates several problems such as attenuation of the photometer signals passing through the satellite sphere and anisotropic response caused by the baffle inside the satellite sphere. An optical system with directional response matched to the cosine law is considered a detector head of a sphere photometer. As a result, we found that by equipping a photometer head consisting of a transparent PTFE diffuse plate, a probe f2 value of less than 10 % can be provided. This indicates the possibilities of optical systems that have a smaller anisotropic response caused by a baffle and brighter throughput than a traditional satellite integrating sphere.
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