Simplifying the composition of the automotive HID lamp electronic ballast has been considered. This paper describes the novel electronic ballast that is composed of a DC/DC converter, a capacitor connected to a lamp in series, a switch (S₃) connected to the capacitor in parallel, a switch (S₂) placed between the output terminals of the DC/DC converter and also connected in parallel to the lamp and the capacitor in series, and an igniter. All MOSFETs (S₁ in the DC/DC converter, S₂ and S₃) in the ballast are operated on the common voltage position (GND) of the circuit. The DC/DC converter is operated intermittently and the operation of S₂ synchronizes with the operation of it to supply the lamp with an alternate square wave voltage. Operating an automotive HID lamp succeeded using the novel ballast and by setting some issues below.
1) The occurrence of the power loss when S₂ is turned on.
2) The occurrence of extinction of gas discharge.
This paper describes how the loss can be decreased if a part of the energy stored in the output capacitor of the DC/DC conveter is used to operate the lamp before S₂ is turned on. It also describes how an inductor and a capacitor were added to the proposed electronic ballast to raise the lamp voltage in order to prevent the current from disappearing.

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Ultraviolet curing systems are used in various fields of industry. Two types of irradiators are commonly used in these curing systems: the parabolic reflector type and the ellipsoidal reflector type. Although the parabolic reflector irradiator is necessarily even, the illuminance distribution does not become even. This study proposes an irradiated plane illuminance calculation method for the parabolic reflector type irradiator. The validity of the calculation method was verified experimentally. In addition, it was clarified that the irradiated plane’s illuminance distribution can be made even by varying the reflectance characteristics of sections of the parabolic reflector.

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The aim of this research work is to establish a standard sky model for designing excellent daylighting schemes that cover all sky conditions from clear sky to overcast sky. In the previous paper (Part 1)¹⁾, the “normalized global illuminance” was defined as a function of the measured global illuminance and the solar altitude for estimating the sky luminance distribution. In this paper (Part 2), the “Relative All Sky Model” is introduced. It offers formulas to show the relative sky luminance distribution as a function of the normalized global illuminance. The equation of the zenith luminance concerning the Relative All Sky Model is also a function of the normalized global illuminance. It is called the “All Sky Zenith Luminance”. An absolute standard sky luminance distribution model called the “All Sky Model” is introduced that is a multiplication of the Relative All Sky Model and the All Sky Zenith Luminance. The All Sky Model can be calculated from the normalized global illuminance, i.e., from the measured global illuminance and the solar altitude or from the measured global illuminance, the horizontal diffuse illuminance, and the solar altitude. The global illuminance and horizontal diffuse illuminance are easily obtained from even the simplest daylight measurements. The All Sky Model can produce an excellent standard sky for daylighting design for any place where an advanced daylight environment is needed.

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The functional visual field (FVF) of target localization against a dynamic background simulating highway driving was precisely measured under four different auditory task conditions to investigate whether conversing on a mobile phone affects a driver’s FVF. The FVF is the visual field in which a person can achieve some kind of visual task, such as target detection or localization. The task conditions were no auditory information, listening to BGM, listening to a simple conversation and understanding it, and listening to a simple question and answering it orally. Individual differences were found in the size of the FVF and the effect of the tasks. The FVF area of the largest subject was twice that of the smallest subject under the same condition. Shrinkage of the FVF was found under the oral answer condition for the two subjects who had never used a mobile phone while driving, while no significant change under any condition was found for the subject who made a long drive every day and was used to talking on a mobile phone while driving. This suggests that conversation can reduce a drivers’ attention and shrink the FVF of some drivers.

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This study aims to evaluate the effect of the lower uniformity ratios on the visual conditions while keeping adequate average visibility level on the road surface. A computer program has been developed to determine necessary criteria for calculations of the road lighting based on visibility level. Five different arrangements such as left single-sided, opposite, staggered, twin-bracket central and combined twin-bracket central & opposite are examined. The results obtained from the calculations for each arrangement by using one typical cut-off, semi cut-off and non cut-off luminaires are classified in two groups as sufficient and insufficient uniformity. It is seen that there are some invisible area even recommended average visibility levels and luminance uniformity ratios are obtained. Because the visibility levels on the grid points may take values different than the average visibility level of the road, a different lighting criterion is necessary to reduce the excessive variation of them. To prevent all possible negative visual conditions, a new road lighting criterion is defined and called as “Average Visibility Level Uniformity”.

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This study focuses on the visual characteristics of buildings illuminated with floodlights, primarily investigating how the visibility of building façades varies according to the distance from an observer. The authors also attempt to compare the visibility of building façades between direct observation and photographic slides. The changes in the appearance of a building façade when illuminated with floodlights can be gauged according to the two stages of “perception” and “recognition.” There is also a typical gap between the visual recognition distances for direct observation and for slide viewing. Generally the visual recognition distance is longer for direct observation that for slide viewing. This is shown by the close correlation between the two types of observation for visual recognition distance for all of the buildings studied.

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We investigated light output properties of white massed-LEDs light sources and their characteristics of temperature rise effects. In the white massed-LEDs light sources with heat radiation countermeasures, we found that the decrease of light output under the high forward current condition was alleviated. The thermal fluid simulation analysis of heat radiation effects of white massed-LEDs light sources indicated that the attaching heat sink to light source board material was effective in not only aluminum board but also glass-epoxy board. And it was confirmed that the LED element temperatures were held less than 60°C in the rated lighting condition for both of them.

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