TOP / Publications / Journal of Light & Visual Environment (JLVE) / Volume 34 Number 1, April, 2010
Study for the Sodium-Loss Locations of High Pressure Sodium Lamp
N. Saito and K. Murakami
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Influence of Xe Gas Concentration on Plasma Parameters and Luminance Characteristics in Fluorescent Lamps driven by an Inductively Coupled Radio Frequency Discharge Using Ne/Xe Mixture Gases
H. Kashiwazaki, T. Kajiwara, H. Fujita and Y. Ohtsu
10
Effect of Operating Frequency on Plasma Characteristics of Inductively Coupled Electrode-less Lamp
T. Uetsuki, M. Ueda, S. Nimata, M. Saimi and H. Kakehashi
16
Thermionic Emission Properties of Emissive Oxides
M. Myojo
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Dimmable Electronic Ballast for High Wattage Metal Halide Lamp
I. Terayama, Y. Umezawa, T. Oosato and Y. Kenmotsu
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Development of a Neutral Point Type Converter and Application as an Electronic Ballast Daylighting
N. M. Hidayat, M. Nakamura, Y. Kato, N. Takahashi,
I. Yokozeki and Y. Itoh
47
From the point of suppressing the increase of lamp voltage and making longer stable life performance of the high pressure sodium lamp, it is important to suppress the reaction of sodium in the arc tube of high pressure sodium lamp during operation. We made the inquiry for the sodium distribution after the long burned lamps. As the result of analysis with arc tubes of high pressure sodium lamp, the reaction of poly crystalline alumina is under 0.1 mg with the wall temperature being the wall temperature kept under 1,100 degree Centigrade after the burning of over 20,000 hours, regardless of electrode constructions. And sodium loss is mainly caused with the sealing frit. It will be requested to raise up the tolerance of sodium for the frit.
KEYWORDS : high pressure sodium lamp, sodium loss, life performance
A mercury-free and electrodeless discharge fluorescent lamp is expected for preserving the environment and a long lifetime. Influence of Xe gas concentration on plasma parameters such as density and temperature of electrons and luminance characteristics is investigated in a fluorescent lamp driven by inductively coupled radio frequency discharge using Ne / Xe mixture gases. It is found that the electron density has a peak value for a Xe gas concentration of 1 % and then decreases with increasing the Xe gas flow rate, whereas the electron temperature takes a minimum value for the Xe gas concentration of 1 % and then increases with increasing the Xe gas concentration. The luminance of the fluorescent lamp decreases remarkably with increasing Xe gas concentration up to 1% and then gradually decreases. The color of the fluorescent lamp changes from red to purple when the Xe gas concentration increases.
KEYWORDS : mercury-free, inductive discharge, plasma parameters, luminance, Penning effect
To increase the efficiency and lumen output of inductively coupled electrode-less lamps, numerous studies have attempted to reduce their operating frequency. This is because if the operating frequency is reduced, a wider range of semiconductor devices can be used that enable higher lumen outputs to be obtained from these lamps. The switching loss can be reduced thus increasing the efficiency. We investigated the relationship between the operating frequency of a 50-W electrode-less lamp and its characteristics. Operating frequencies of 13.56 MHz and 135 kHz were used. The characteristics that we investigated are its starting characteristics, the plasma characteristics (such as the temperature and density of the electrons), and its efficiency in producing UV radiation. The results show that the efficiency in producing UV radiation at 135 kHz is 7% lower than that at 13.56 MHz, and that plasmas generated at operating frequencies of 135 kHz and 13.56 MHz had different electron-density and electron-temperature distributions because of the different power input positions.
KEYWORDS : electrode-less lamp, electron temperature, electron density, magnetic coupling plasma
Emissive oxides are employed as a thermionic emission material on electrodes in fluorescent lamps. In the previous paper introducing a new method for measuring the work function of fluorescent lamp electrodes with emissive oxides, the temperature dependency of work function was dealt with. Further discussion to clarify the relationship between the temperature dependence of work function and the effective value of the Richardson constant was performed in another previous paper. Together with being translated them into English, this paper newly performed other discussions of verifying the slope of the linear line in the relationship with reference to the historical data for tungsten metal and of reconfirming the necessity of applying photoelectronic procedure besides thermionic one in order to measure thermionic emission factors other than work function and the Richardson constant. In particular, the approach to measure donor density is helpful to understand the importance of introducing both photoelectronic and thermionic procedures.
KEYWORDS : work function, temperature dependence, emissive oxide, thermionic emission, Richardson constant, donor density
Daylighting is highly significant from the viewpoint of energy saving and healthy life. However, considering density of housing in residential area of large cities, it is very difficult to secure sufficient daylight and lead daylight to whole space in the house. High side lighting is one of the solutions for such situation. And when high side windows are designed with open ceiling, high side light can be propagated to lower level through open ceiling. On the other hand, high side light brings highlight area on walls or floors. The area may cause glare phenomenon or may lower brightness of surrounding area by contrast effect. And open ceiling may cause excessive impression of air volume for detached house. This paper reports designing of diffusing screen to solve these problems. The screen is designed to meet the condition of existing detached house in densely built residential area considering the way of sunlight, the shape of detached house and the use of the detached house. The designed screen was simulated by computer graphics images. Finally, designed screen was installed to the house. And authors made clear that the screen realize required objectives through measurement survey. The screen was also designed to work as lamp shade at night.
KEYWORDS : daylighting, high side light, open ceiling, diffusing screen, highlight
This paper presents a commercialized dimmable electronic ballast for 1000 W metal halide (MH) lamp and its application. The ballast is a three-stage power converter. It is composed of boost converter to achive high power factor, buck converter to control lamp power, and an inverter to supply the lamp with low-frequency square-wave current. The power of 1000 W MH lamp can be varied linearly in the range from almost 65 % to 100 % with on-duty of the external control signal. Low current distortion, high efficiency of the ballast (94%), and low lamp power variation (less than 0.4%) are achieved. Furtheremore, an application of the ballast to a factory with high ceiling is demonstorated. As a result, we could achive reduction in energy consumption in the site.
KEYWORDS : electronic ballast, dimming, metal halide lamp, low-frequency square-wave
A previously developed two converter method electronic ballast, a combination of converter and inverter circuits, satisfies the IEC 61000-3-2 class C harmonics standard. However, this method had many faults. To further improve the system, we propose a neutral point type boost converter and confirm by experiments that the proposed converter could be used as an electronic ballast. However some problems that were caused by boost operation still remained. Therefore, we propose here a new neutral point type buck-boost converter circuit that remedies the problems. We show that the proposed converter can be used as an electronic ballast and achieved extensive results.
KEYWORDS : electronic ballast, buck-boost converter, one-converter