The speckle phenomenon, which is discoloration on the inner surface of a lamp tube, sometimes appears in rapid-start fluorescent lamps with internal starting aids. There is a great deal of patent literature on methods of preventing this phenomenon but most of it is experimental or fragmentary. We analyzed this phenomenon by numerical analysis with a computer and were able to gain a comprehensive understanding of a mechanism of its occurrence and were able to obtain ideas on how to prevent it.

KEYWORDS:rapid-start fluorescent lamp, speckle phenomenon, numerical analysis

High-frequency fluorescent lamp operation requires proper cathode preheating by electronic ballasts incorporating a preheating function. This paper examines minimum thermionic emission curves for three different ways of measuring emission times. One is based on a lamp ignition test, another on the ratio of hot to cold coil resistance (Rh/Rc), and the third on the lamp voltage monitoring. The observation that the emission time measured by the lamp ignition method tends to be shorter than that measured by the lamp voltage monitoring method in a short preheat time may be understood in terms of the relaxation of the limited thermal conductivity of the emissive material due to the initial flow of the discharge current. We do not believe that the shorter emission time measured by the lamp ignition method causes premature thermionic emission. On the other hand, when the duration of the heterogeneous heating in a cathode is negligible, then the Rh/Rc method may be used as well. This paper points out that the average resistance of a standardized cathode over the period up to the emission time should be regarded as a substitution resistor. Furthermore, a maximum curve similar to the minimum preheating requirement curve, being examined to replace the maximum preheating broken lines for the present requirement in the IEC, is helpful for determining a new coming maximum required energy line. In the last part of this paper, an approach to the standardization by a preheating energy line together with a suitable value for the substitution resistor is supported.

Cold cathode discharge lamps are usually operated with a capacitor ballast, and are supplied by a high-frequency sinusoidal voltage. At some frequencies of the supply voltage, the current waveform of the positive period differs from that of the negative one and the luminance of the lamp is lower than when the current waveform is symmetrical. In an asymmetrical waveform, the current waveform in one half-cycle is pulse-like with a high peak and the waveform in another half cycle has a low amplitude. We calculated the equation of a simple equivalent circuit, and found that the discharge current consists of a sinusoidal steady component and a transient pulse component which increases as the delay time for re-ignition increases. The asymmetrical waveform of the discharge current occurs when the supply voltage, the operating frequency, the lamp diameter, or the capacitance of the ballast is decreased. Since decreasing the value of those parameters increases the delay time for re-ignition in one half-cycle, the re-ignition voltage drops and the delay time for re-ignition becomes shorter in the other half-cycle.

KEYWORDS: capacitor ballast, high-frequency operation, cold cathode discharge lamp, neon lamp, delay time for re-ignition, re-ignition voltage

The characteristics of xenon-neon discharge fluorescent lamps with inner electrodes and of xenon discharge lamps with external electrodes are described in this paper. All these lamps were operated at pulsed discharge. In the case of inner electrode type, when the partial pressure of neon is high, the ignition voltage is low because of the Penning effect. Then, the high mixing ratio of neon is desirable for the lower ignition voltage. However, the luminance of phosphor increases as the mixing ratio of xenon increases. Therefore, in order to obtain high luminance, xenon should be filled at high mixing ratio. In both cases, that is, inner electrode type and external electrode type, as the pressure of xenon increases, the afterglow peak of phosphor emission increases. These increases seem to be caused by the VUV radiation of xenon excimers. The emission of light from phosphor shows that xenon excimers are generated effectively by pulsed discharge of high pressure xenon, because they are generated by three-body collision at the low electron temperature Te during the non-discharge period.

The continuously emitting 4.2 eV, 3.2 eV and 1.9 eV photoluminescence (PL) bands were measured for as-manufactured and neutron-irradiated silica glasses. In the as-manufactured sample, the intensity of the 4.2 eV decreased with increasing temperature from 77 K to 550 K. The 3.2 eV band observed at room temperature was too weak to be observed at 77 K, and the intensity increased till 80 °C, and decreased above 110 °C. In the neutron irradiated sample, the intensity of the 4.2 eV PL band increased, and the peak position shifted to 4.37 eV. After annealing to 600 °C, the intensity at room temperature became weaker than the original, and the peak position continued to shift to higher energy side. On the other hand, the intensity of the 3.2 eV PL band decreased drastically and almost disappeared, and any shifts of the peak position were not observed. After annealing to 700 °C intensity at room temperature began to increase, and the peak position kept the original position. The 1.9 eV PL band was observed after neutron irradiation, and depended on the OH content in the as-received samples. After annealing, the intensity of the 1.9 eV band increased gradually up to 450 °C and then decreased and almost disappeared at 700°C.

The Monte Carlo method, which has recently been widely used to predict the illuminace distribution of a room arranged in a complicated way with furniture, is an easier algorithm than others and is suited to simulating the various states of lighting in a room. The accuracy of the illuminance distribution calculation is affected by the number of particles that substitute for the luminous flux of the light source and by the number of elements of the room surfaces. Therefore, we investigated the optimal number of the particles and elements considering the CPU time and error rate of the illuminance calculation when a shadow caster assumed to be a worker's head was set at an arbitrary position in a rectangular parallel-piped model room. A new method, which uses the incident particles on the surrounding elements of the calculation point, was developed to decrease the CPU time and calculation error. We examined various reflectances of the room surfaces, positions and diameters of the shadow caster. As a result, using only 1/10 the CPU time of previous methods, we found that the optimal number of particles is five million and the optimal number of elements each surface of a room is 40X40 to 60X60.

Shadow is something we experience in our daily lives and a significant obstacle to our work. So shadow has been considered one of the important factors in lighting design. In this paper, the illuminance distributions on a desk as the working plane when Task Ambient Lighting, which is one type of office lighting systems, and a globe as a shadow caster are set up in a model room containing fixtures are obtained by the Monte Carlo method and the characteristics of the shadow are examined. First, in order to carry out the illuminance calculation by the Monte Carlo method in the case of a light source with a non-uniform diffuse distribution, the relationship between the cumulative luminous flux and uniform random numbers was found by the use of division mensuration. Next, some experiments were made under the same conditions as the calculations. Comparing the experimental results with the calculated results, difference between them, confirms that the above method is suitable. Then, we obtained and examined the shadow characteristics on the surface of the desk when the position of the shadow caster was changed. As a result, we found that Task Ambient Light makes a weaker shadow than one of Task light or Ambient light, and variations in the shadow area by Task Ambient Light are similar to those by Task light.

KEYWORDS: Task Ambient Lighting, Monte Carlo method, illuminance calculation, shadow

The purpose of this study is to clearly define the meaning of affluent lighting in a living room and together with its concerned elements. Two psychological experiments, one using the evaluation grid method and other using the semantic differential method, were carried out using photographs of living rooms.

(1) 24 meanings and 41 elements emerged from the results of experiments using evaluation grid method. Relationships among the 24 meanings were plotted in a figure using MDS. The 41 elements were classified into six groups.

(2) The meanings of affluent lighting were explained by feelings of comfort, brightness, and variety from the results of experiments using the semantic differential method. The important elements were plural luminaries and brightness.

The results show that affluent lighting can suit various situation in a living room.

A comparison of relative spectral responsivity measurements of illuminance meters was carried out among five companies - TOPCON Corp., HIOKI E.E. Corp., Minolta Co., Ltd., Yokogawa M&C Corp., and Matsushita Electric Industrial Co., Ltd. The spectral responsivitys of the illuminance meters were measured by each company's spectral responsivity measurement system calibrated to each company's standard. As a result, the measured values of fs (fs is defined as the relative spectral responsivity error in Japanese Industrial Standard JIS-C-1609) differed within 1.7. The fs is identical with the f1' recommended by the CIE.

KEYWORDS: illuminance meter, spectral responsivity, Japanese Industrial Standard