J. of IEIJ Vol.85, No.2

A ballast circuit with an inverter combined with a chopper is a circuit in which the inverter and chopper share at least one switching element. We have developed a ballast circuit with a newly designed dimming control circuit and drive circuit. Dimming control (Complementary PWM control) is achieved by making the continuity time of one switching element (Q1) longer, while making the continuity time of the other switching element (Q2)shorter, and vice versa. The drive circuit (self-excited and externally-excited multi-drive circuit with switching element Q1) is self-excited by the feedback of the oscillating current from the resonance circuit. while switching element Q2 is excited by the external signal. This circuit can run a pair of fluorescent lamps (FLR40S/M). An input power factor of 98% or more, a THD of 13%" or less, and no substantial variation in the smoothed DC voltage were obtained under three conditions : full power (100% light output ratio), dimming level 1 (80% light output ratio), and dimming level 2 (55% light output ratio).
KEYWORD?Felectronic ballast, dimmer, inverter, chopper

A novel cold cathode fluorescent lamp (CCFL) with an adiabatic layer suitable for backlighting of PDAs (Personal Digital Assistants) is described. The adiabatic layer (100-200ƒÊm) is formed between a light tube and an outer tube and is filled with low-pressure gases. This raises the temperature of the light tube to the suitable value (50-70), which maximizes efficiency even in low lamp wattage operation and in low ambient temperature. The results of experiments and heat transfer analyses show that the optimum pressure in an adiabatic layer lies between 1 Pa and 10 Pa. At a pressure of less than 1 Pa, the lamp maintains the temperature at a constant level because of the conduction loss is lower than the radiation loss.
KEYWORD:cold cathode, fluorescent lamp, heat transfer, free-molecule flow

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 . 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.
KEYWORD:Ffunctional visual field, target detection, target localization, driver's visual ability, mobile phone, attention

One method for determining the impedance of an inductively coupled low-pressure argon plasma tube is described. Designed for application to inductively coupled fluorescent light sources, it was a spherical discharge tube and an induction coil wound on its equatorial surface. The pressure of the argon gas is around 100 Pa, and the frequency of the rf coil current is around 10 MHz. By assuming uniformity of the plasma density and electron temperature, an analytic solution for the electromagnetic field is easily obtained. Using this solution, we can obtain a convenient approximate calculation of the spatial distribution of the electric current and plasma impedance. The results of numerical calculation of impedance are given and compared with experimental results.
KEYWORD:inductively coupled discharge, low-pressure argon light source, calculation of impedance

Lighting products consume about 20% of total electric power, so the lighting industry should take a large responsibility for energy saving. Fluorescent lamps are a particularly critical light source for energy saving because they are widely used. Although the fluorescent lamp has high efficiency. its energy-transition rate is still as low as 25%. There is thus much room for improvement.
The key issue for efficiency improvement is the phosphor technology. Phosphors have been researched and improved based on the one?õ?photon emission theory. Currently, the highest phosphor efficiency (transition rate of UV to visible) is over 40%. However, the energy of 254nm UV photon of Hg discharge is 4.9eV, which could be transferred to two visible photons.
We investigated the feasibility of the two-photon approach. We specifically studied a phosphor with an activator of a metal atom in an atomic state, which produces atomic-like emissions from an isolated metal atom fixed in a matrix. First, we theoretically studied the selection of possible metal atoms and analized the probability of two-photon emission. We searched for a method for fixing and isolating atoms in a matrix at room temperature and analyzed the energy shift of an excited atoms. As a result, we could have a prospect of the feasibility. Next, we conducted an experiment to fabricate a new phosphor sample by fixing an atom in an atomic state in a matrix and evaluated the performance of the samples. We selected Fe atoms, an amorphous silica as a matrix, and sol-gel fabrication method.
We found that Fe atoms on a silica matrix were fixed in an atomic state by sol-gel fabrication and emitted fluorescent light at lower atomic densities. However, the emission was not made by the visible two-photon transition, but by continuous deep-blue continuos emission.
KEYWORD: phosphor, two-photon emission, atomic activator, high efficiency, fluorescent lamps

Natural light should be effectively used for a low-energy-consuming daylighting design. A useful sky luminance distribution model is thus required for estimating and evaluating a daylit environment as a standard sky. We previously developed a standard sky model named the ALL SKY MODEL. It can represent the sky luminance distribution from clear sky to overcast sky continuously.
 We have now modified the procedure for constructing the model so that the index for estimating the sky luminance distribution can be derived easily.
The standard global illuminance was defined based on global illuminances of clear skies. The normalized global illuminance was obtained by dividing the measured global illuminance
with the standard global illuminance, and was selected as the index for estimating sky luminance distribution.
This paper describes the new construction procedure: the gathering of raw data the arrangement of data and the selection of indices for estimating the sky luminance distribution. It also reviews various standard skies proposed by researchers worldwide.
KEYWORD:sky luminance distribution, standard sky, daylighting design, All Sky Model

 The economic value of light pollution was evaluated using the contingent valuation method as the basis of a survey by questionnaire of residents of urban areas. Comparison of the evaluated value with the subjects' environmental consciousness in general and their environmentally friendly behaviors in daily life suggested valuable methods for deeply understanding consciousness of light pollution.
KEYWORD:contingent valuation method, light pollution, environmental assessment

 Short-, medium- and long-wave infrared emitters have different effects on the temperature-rise and drying-rate characteristics in infrared radiation heating of water containing flat material. Accordingly they also significantly affect thermal efficiency. The heating characteristics also depend on the thickness of the heated material. It is known that absorbed radiation flux changes to heat within the heated substance, the absorption depends to a large extent on the amount of water in the substance, and the Lambert absorption coefficient of water varies significantly between the three wave-length regions. The coefficient is higher in the long-wave region, moderate in the medium one, and much lower in the short one. We assumed that the infrared emitter used was a black or perfectly grey body and that the heated substance acted as free water, and calculated the irradiance and generated heating-power distributions within the substance. The thickness in millimeters of the substance needed to absorb about 90?“ of the incident radiation flux is indicated by D's in the Figure and Table. The heating-power generated at the irradiated surface when heated by a long-wave emitter was noticeably higher. The high drying-rate, which is characteristic of long-wave emitter heating, is attributed to the concentrated heating-power at the irradiated surface. This high heating-power provides large latent heat for evaporation. The obtained results of Figures and Tables give basic and useful Informations for choice in advance of the emitter kind between the three ones in infrared heating of a water contained substance with a given thickness.
KEYWORD:infrared heating, infrared drying, long-wave infrared heating

Study on Color Temperature Error Observed in the System of Combined RGB Fluorescent Lamps
Shigeo GOTOH, Ichiro FUJITA and Motoi WADA

 The color temperature of the light generated by the illumination system of the combined RGB fluorescent lamp system was shown to disagree with the estimated value obtained from a simple model based on lighting data for three single fluorescent lamps. The discrepancy was not caused by the change in the light spectrum of each lamp due to the input power control, but was caused by the change in the luminous flux from the lamps. The error in the luminous flux estimated for the given lamp power was attributable to the spatial distribution of the light emission from the lamp. The magnitude of this error was typically 2 to 3%.
KEYWORD:fluorescent lamp, luminous flux, color, dimming