Journal of Light
&
Visual Environment

Volume 29 Number 1, April, 2005

CONTENTS

Papers

Research Notes

English Abstracts

 A simple and novel circuit model of the electrical characteristics of arc discharge of fluorescent lamps has been developed. The model has the features necessary for electrical circuit design, and enables circuit simulation with consideration of the effect of the electrical behavior of the discharge lamp, including the effects of some abnormal conditions. Although the model equation is a simple polynomial expression, each term is based on physical considerations, and non-linear and non-steady discharge phenomena have been successfully modeled. The model can express most aspects of lamp operation, and results quantitatively correct values over a wide operation frequency range. It also reproduces abnormal conditions such as worn-out lamps and rarely reproduced phenomena. The model is constructed as a combination of primitive circuit elements. Consequently, combined with a designed ballast circuit, one can easily perform circuit analysis by using a general-purpose circuit simulator. The model will be a very powerful tool for lamp ballast and peripheral circuit design.

KEYWORDS : fluorescent lamp, arc discharge, circuit model, cathode fall, diffusion

Finite-Element Stress Analysis and Strength Evaluation of Super High Pressure Mercury Lamp Bulbs under Internal Pressure
M. KASE, Y. IWAMA and T. SAWA

 Super high pressure mercury discharge lamps have been used as UV light sources for photolithography, such as patterning LCDs, PCBs and semiconductors. The bulbs of the lamps are generally made of silica glass. This study evaluates optimal shapes for various lamp bulbs under internal pressure employing the Finite Element Method(FEM). As the result, the optimal shape of the bulb was obtained and the relationship between the rupture stress and the bulb wall thickness t was clarified. The optimal shape of the bulb obtained is 0.7 ≤ D /L ≤ 0.85, where L is the total length of the bulb and D is the diameter. Static water pressure-tests were conducted in order to verify the numerical results. It was found that tendency between the numerical results and experiments were in fairly good agreement.

KEYWORDS : super high pressure mercury vapor lamp, lamp bulb, tensile strength under internal pressure, optimal shape of lamp

 The sky glow in Tokyo is considered to be caused not only by excessive upward light output from outdoor lighting. The purpose of this study is to determine the influence of the light from windows of office buildings on the sky glow in Tokyo. In order to identify the actual conditions of the spill light from office windows, field measurements were conducted in a park and, based on the results, the upward luminous flux from office windows was compared to that from outdoor lighting investigated by Illuminating Engineering Institute of Japan(IEIJ). Our research proves that it is necessary to consider not only the outdoor lighting but also the light spilled from the inside of buildings.

KEYWORDS:sky glow, spill light, office windows, upward luminous flux

 This study was conducted to examine how our visual impression of the lighting space will change when the ratio of the amount of daylight from a window to light from an entire ceiling is changed. In order to evaluate the subjective impression of illuminance distribution for lighting conditions, this study adopted an experimental method using two scale models. The standard box was lit by only the light from the entire ceiling, and the evaluation box was lit by the light from the window and the light from the entire ceiling. Subjects were asked to rate their overall impression for the state of light in the evaluation box by comparing with standard box. Our findings indicate that the compound ratio of 20 to 40% from the window and 80 to 60% from the ceiling would be beneficial in terms of psychological impression for ordinal office spaces.

KEYWORDS : daylight, artificial light, visual impression, compound lighting

An Electronic Ballast Using Back-boost Converter
I. YOKOZEKI, Y. KATO, T. KURATANI, Y. OKAMURA, M. OHKITA and N. TAKAHASHI

 The new circuit of the electronic ballast for a fluorescent lamp, which is based on the back-boost converter, is proposed. This circuit has the advantage further than the circuit that combined the converter for rectification with the inverter for lighting in some points. Those advantages are reduction of the number of elements and improvement in the circuit efficiency, etc. And this circuit also satisfies regulation value of IEC class C on the relative harmonic contents of input current. From experimental results, the effectiveness of the proposed circuit is shown.

KEYWORDS:neutral point type, back boost inverter, IEC class C, inrush current

Study of the Halogen Volume on the Tungsten Halogen Lamps
K. SHIMOGAKI and H. YOSHIIKE

 Halide is sealed up inside a tungsten halogen lamp. The action of the halogen allows the lamp to maintain its initial luminous flux without being blackened until the end of its service life. The quantity of halogen, if insufficient, blackens the lamp and shortens its life. If excessive, however, the halogen may affect the lamp’s efficacy and service life. Although an appropriate value of quantity is consequently required, this can only be calculated by means of a great number of trial production and life tests, due to the theoretical complexity and associated factors. These tests are time consuming and expensive. The aid value is therefore often determined on the excessive side to simplify experiments, thereby avoiding any risk of blackening. We used theoretical calculation for some success to determine an optimum value. We therefore aim to improve the production technology by applying our theoretical calculations to trial production and life tests.

KEYWORDS : tungsten halogen lamp, evaporation of tungsten, theoretical calculation, proper halogen volume, chemical reaction in tungsten halogen lamps, blacking on tungsten halogen lamps

The Influence of Dimming in Road Lighting on the Visibility of Drivers
A. BACELAR

 Last years, people who are in charge of road lighting try to carry out energy savings but they do not really care about user considerations. This paper presents experimentation with observers, who were asked to assess the visibility of targets on the road surface under different levels of illumination (promoted by dimming). For our lighting installation, dimming does not influence the visibility of drivers very much and one can say that it affects less the visibility than the position of the target. Nevertheless, luminous flux reduction must be done with good and homogeneous lighting installation otherwise road users may have problems of visibility and comfort.

KEYWORDS : dimming, energy saving, visibility, road lighting, comfort, experimentation