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Low pressure mercury arc lamps are an effective ultraviolet light source for disinfection of water. Critical lamp operating parameters such as the decrease in UV output with time, effect of water temperature on lamp output, and the effect of lamp dimming should be determined using a lamp in water. The reliable operation of a near-field test apparatus is described that is capable of measuring these quantities. The use of a radiometer with fiber optic light collection and standard reference lamp results in the reproducible measurement of these values using the near-field system. The stability of measurement is obtained using the reference lamp, which compensates for variations in the response of the fiber optic assembly. For sample lamps, a decrease of 11% output over 12,000 hours was observed. For the same lamp type, the relative calibrated output of the lamp increases between 5 and 50°C, with a ±10% change in lamp output relative to the reference temperature of 20°C. The apparatus samples the irradiance at a local point on the lamp, but the UV output of low pressure amalgam lamps as determined by the near-field technique is shown to be uniform over the entire lamp, except for within 1 cm of the lamp filament. This is shown for both new and 12,000 hour aged lamps, so that accurate lamp aging data can be determined. The change in UV output with water temperature change was demonstrated to be similar for both new and aged lamps in this study, except for the expected decrease in peak lamp UV output noted for the aged lamp.

Thoriated-tungsten (ThO2-W) is popularly used for the electrodes of a super-high pressure mercury lamp, or for arcwelding, because of its excellent performance as to the electron emission. Because it is radioactive, however, a new material which can replace it would be desirable. To find a material to replace ThO2W as the electrode, we have made many kinds of electrodes by a new process, which is different from the traditional process, and evaluated their performance. We have found that neodymium oxide or samarium oxide made by the new process produces encouraging results.

Conventional flash lamps use Xe because its radiation spectra is close to those sunlight. Recently, new applied uses of flash lamps, such as sterilization and surface modification, are attracting attention. We developed a flash lamp effective for these uses, that emits light with higher radiant efficiency in the ultraviolet ray region We optimized the lamp specifications and lighting method, and examind a new gas(Kr) and a mixture of gases(Kr.:Xe=90:10) to be enclosed in the discharge tube.

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.

Self-ballasted compact fluorescent lamps (CFLs) have been developed and improved in these twenty years. In Japan, the CFLs that have diffusive glass globes to replace incandescent lamps have been developed, but their sizes were too large to fit in the luminares of incandescent bulbs. Thus, we have developed the self-ballasted CFL of an "A60" bulb shape, which has the maximum diameter of φ60 mm and the length of 123 mm. This lamp could be substituted for a 60 W incandescent lamp. In order to realize this lamp size, we optimized the discharge tube diameter, filling gas type and pressure, the shape and making-process of the discharge tube. After all, the triple-"U" connected tube is selected, which has a decisive advantage against a multi-folded tube on the luminous maintenance during life, but also has a disadvantage on the luminous run-up characteristics. We investigated the behaviors of mercury, especially the mercury diffusion phenomenon released from the auxiliary amalgam-flags after ignition by both experiments and calculation. The luminous run-up characteristic has been much improved.

Methods were investigated to improve the lamp characteristics of inductively coupled electrodeless metal halide lamps to make them practical. First, evaluating lamp efficacy by adjusting the lamp parameters showed that a lamp efficacy of 180 lm/W (Including coil loss: 151lm/W) white color could be attained. Second, the conditions generating free iodine and bulb deterioration, the main factors limiting the life of these lamps, were investigated. For long-life-type lamps, which had 130 lm/W of lamp efficacy, the lamp lumen level did not decrease during 21,000 hours of overload operation (corresponding to 58,000 hours of rated-load operation). These lamps thus have excellent lumen maintenance and life performance compared with conventional electrode metal halide lamps. Third, improving circuit reliability by decreasing the Q value of the resonant circuit was investigated for long-life-tpye lamps which had 145 lm/W of lamp efficacy. The relationship between the Q value and the lamp parameters was analyzed, and the Q value was decreased to 78% its value while maintaining the same lamp performance.

Mercury which is used in fluorescent lamps for general lighting has a possibility to cause environmental problems. Authors have been developing lamps which contain only rare gases without mercury. The rare gas lamps are environmentally-friendly, but it has lower luminance than the mercury lamp has. Therefore, the authors have tried expanding positive column by using an external electrode, and 12000 cd/m2 was achieved by cylindrical xenon fluorescent Lamp. In this paper it is reported that the same method is also useful for flat lamps with multi anodes. An external auxiliary electrode controls electric field and potential in the flat lamp. The external electrode is effective to expand the column in a flat lamp and make it uniform and finally improve luminance.

A new metal halide lamp employing gadolinium-lutetium iodide additives for LCD projector usage has been developed. Emission from gadolinium-lutetium iodides contributed to a significant improvement of various color characteristics. The new additives also led to a longer lifetime of the lamp. Besides, the designing of a reinforced arc tube has been realized through the fracture behavior analysis, providing a highly reliable arc tube.

Tri-color type fluorescent lamps have been improved in their performance by various research efforts since the introduction to the market. In recent years, however, small size lamps have appeared and phosphors with superior resistance have been required under the severe conditions of these lamps. When compared with green phosphor and red phosphor, (Sr,Ba,Ca)10(PO4)6Cl2: Eu blue phosphor(SCA) is particularly easy to deteriorate. To investigate the causes of deterioration of SCA, we made serial experiments by the demountable discharge lamp apparatus (DDLA) and the fabrication of actual fluorescent lamps. It is noticed that ion bombardment and mercury absorption are related to the deterioration of SCA lamps. Surface coating is found to be effective to decrease the influence of both.

Recently, low wattage HID lamps are developed and used steadily for an indoor illumination such as offices or stores. The ballast for the lamps is required to be in smaller size and lighter weight, and moreover it is required to have excellent function with good controllability. If the simulation model of the HID lamps is given for the behavior in transient such as in starting period, it is very useful for analysis and design of the ballast. In the paper, a simulation model for high pressure mercury lamps is proposed by means of state variable method. The equations are taken account of the state of each portion such as pressure, temperature and mercury vapor density, etc. The coefficient values of the equations are investigated physically and determined referred to experiment. The calculated results are in good agreement with the experimental results. Then, it is verified that the simulation model is available for the high pressure mercury lamps.

We investigated the start characteristics (decreasing the breakdown voltage and increasing the luminous flux during run-up time) of mercury-free metal halide discharge lamps. Breakdown voltage of mercury-free metal halide discharge lamp could be reduced if the gas in the outer envelope is Xe or Xe/Ne. Adding indium iodide and supplying higher electrical power could increase luminous flux during run-up time. The run-up requirements in ECE regulation No. 99 can be achieved by supplying 90W of power to the lamp during run-up time.

The Monte Carlo method is applied to the predetermination of a luminous intensity distribution in luminaire design. In this technique, the random travels of light quanta such as photons are statistically analyzed to obtain the luminous intensity distribution. That is, the behavior of many photons are determined using random numbers. The photon paths are traced until either they are absorbed by intercepting surfaces or until they are emitted outside the luminaire. Basic procedures of simulating photon emissions and photon reflections are described. These procedures together with photometric properties measured on elements composing a luminaire, are applied to predetermining the luminous intensity distribution of a luminaire composed of a fluorescent high pressure mercury lamp and a reflector with a blasted aluminum surface of revolution. It is revealed that approximately 106 trials are required to predetermine a luminous intensity distribution with a precision of 1%.

The present research has been conducted with a view to energy saving and contemplates to use a single three-leg iron-core reactor in place of two core type iron core reactors used respectively in the capacitive and inductive ciruits of the conventional flickerless lighting device of the two-lamp or dual high pressure mercury lamp. It has become apparent from this research that, with the length la of the two air gaps between the central leg and the respective outer legs selected to be equal to 2mm, the capacitive and inductive circuit can be made substantially independent from each other and that, for the same voltages and currents in the various operating portions and the same mercury lamp power rating, the volume of the silicon steel plate and the iron loss can be reduced about 18% with the novel lighting device as compared to the conventional device.

Calculations of the luminous flux which is an output of discharge lamps are necessary in the overall analysis of the operating circuit for such lamps. In this paper, we calculate the instantaneous luminous flux of a 40 W clear mercury lamp operated by simple two circuits: one is a resistance type operating circuit, and the other a chopper type operating circuit. After the discussion on the relationship between the lamp’s instantaneous conductance and the temperature of the arc plasma in discharge lamps, the instantaneous temperature of the arc plasma is determined by the lamp’s instantaneous conductance which can be calculated by using the lamp model equation. Then, the instantaneous luminous flux, which depends on the sum of the line spectral intensities, is calculated by this instantanous temperature of the arc plasma. Finally, the usefulness of this calculation method is discussed, comparing the calculated results with experimental results.