Effect of light irradiation on ignition property of low pressure fluorescent lamp was examined experimentally. Discharge starting voltage of the straight fluorescent lamps, which had no fluorescent substance coating and 50cm electrodes-gap, were measured at several conditions of light irradiation. As results, followings were clarified, (1) region, which is not far from the anode (<10cm), only has effect to increase the discharge starting voltage up to 200V (at several cm from the anode) on the occasion of light irradiation, (2) wavelength of irradiating light, which lies between 300nm and 500nm, only has effect to increase the discharge starting voltage.

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The light emission luminance using Ne-Xe mixture gases was observed in radio frequency electrodeless light source. The results are fundamental research for light source with long life time and non-mercury gas. Plasma with Ne-Xe mixture gases produced by the injection of radio frequency (RF:13.56MHz) power. The RF power was changed from 20 to 140 W, while the total gas pressure was changed from 0.1 to 2Torr with keeping 0.5Torr of Xe gas Pressure. The light emission luminance for total pressure 1Torr was highest with 400cd/m² at RF power 140W. On the other hand, Electron density increased with increasing the RF power to 2×10¹⁰cm^-3 at both 1 and 2Torr.

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To complete the system solution for end of life of fluorescent lamps(EOLL), the mechanism to cause the EOLL phenomena need to be understood well. We surveyed the phenomena including tungsten sputtering from an electrode after dissipating an emissive coating on it. After that we suggested that after the filament coil was broken the comparison between the resistance in a stem-glass and glow discharge impedance values at an interval of inner-leads could indicate the viewpoint whether the stem-glass would start melting or not. The intermittent pulse discharge, one of ways to heat a stem-glass, was investigated why and how it was generated. It is concluded that to heat a stem-glass partially is a dominant factor to lead to the final stage of EOLL and to deposit a tungsten film on a stem-glass between inner-leads by sputtering is a subsidiary one.

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Now, BaMgAl₁₀O₁₇:Eu²⁺(BAM) is used as a blue phosphor for 3-band type fluorescent lamps. However, BAM is unstable compared with a green or a red phosphor. Especially, the luminescence intensity decreases in the manufacture process of a fluorescent lamp, and it has the problem of process degradation that a color shift takes place. We development the research of the stable new blue phosphor which replaces BAM and show the CaMgSi₂O₆:Eu²⁺(CMS) phosphor as one of them. Here, the characteristic of CMS phosphor as a fluorescent lamp is reported.

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[in Japanese]

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[in Japanese]

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As for large display cells using Xe barrier discharge, the dependence of the luminous efficiency on the distance between a surface electrode and an inner electrode is measured. 8 cells are shared a discharge tube which is 12mm in diameter, 300mm in length, coated with the Green phosphor (LaPO4:Ce,Tb), operated by high voltage pulse (f=70kHz, pulse width=2μsec). As a result, the efficiency is increased with the distance between electrodes, and the maintenance voltage is decreased with it.

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We developed the new borate phosphor and the flat-type fluorescent lamp emitted ultraviolet light for high efficient excitation by vacuum ultraviolet light. The new phosphor is a Gd doped YAl₃(BO₃)₄ host crystal. The photoluminescence line at 313 nm was observed and stimulated for vacuum ultraviolet light. Furthermore, it is about 14 times the luminescence peak intensity compared with the commercial ultraviolet fluorescent phosphor. The flat-type fluorescent lamp was developed using a new phosphor and the optical glass. As a result of performing, it has checked that ultraviolet light intensity was maintained for a long time compared with the conventional fluorescent lamp.

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We studied characteristics of mercury-free flat fluorescent lamp. Parallel two electrodes are printed on inner-side of front glass, and dielectric layer covers electrodes. Both lamps with and without MgO layer on dielectric are examined. Filling gas is Xe-Ne-Ar mixture. Inverter is used for operation. Lamp efficacy with MgO is better than without MgO. Maximum efficacy is 22.0 lm/W at 6000 cd/m². Breakdown voltage of lamp with MgO is lower than without MgO, and is not increased in dark space.

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For circuit configuration of boost type PFC converter followed by half bridge inverter, the loss is decreased by setting the argument of the load circuit small. However, the effect of current limiting of the load circuit is reduced. Although the control method of current limiting, that dc voltage of the PFC converter is controlled to regulate a lamp current, has an effect, we have to consider the control stability. We examined the improvement of the control stability by measuring the looped transfer function of the circuit. A lamp is operated stable with the high efficiency lighting circuit in result.

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We frequently use quartz tube metal halide lamps enclosed Sc-Na doses, because they are high lamp efficacy and good color rendering. But it is well known that sodium loss is occured during operating time, and low lumen maintenance and short life result from lamp voltage rising. So controlling sodium loss is useful for improvement of lumen maintenance and for longer life. Sodium loss is generally occurred by quartz tube temperature rising, electric field around quartz tube, and photoelectron attachment on quartz tube. This time, we tested out controlling sodium loss. Finally, it is concluded that filling of Sc-Na-I-Br doses, and potential floating of outer bulb mounting supports are useful for reducing sodium loss.

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The starting property of inductively coupled electrodeless metal halide lamps was evaluated and analyzed. Effects of the lamp parameters and of the circuit driving form on the starting property were investigated. The evaluated lamp parameters were, types and pressures of filled rare gas, gaps between arc-tubes and the induction coil, an applied voltage on the starting aid discharge tube, and the applied voltage shapes on the starting aid discharge tube. And more, effects of a free iodine gas, and the times to become ready for restart were evaluated. The evaluated circuit parameters were, phase difference between the applied voltage on the starting aid discharge tube and the induction coil terminal voltage, and wave forms (flat and ripple outline RF modulated) of the induction coil.

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It has been developed a new microwave discharge lighting system. The cavity has a small diameter than the cut-off microwave length and the cavity length is longer than the diameter. For example, a cavity which has aparture diameter 48.5mm and the length 230mm, has been operated with coaxical mode, to input the high frequency power into the discharge tube at 2.45GHz. The distance from the aparture to the top of the tube is longer than the cavity diameter. The system can be operated as a light source with no microwave emission from the aparture without metal mesh for electromagnetic shield.

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[in Japanese]

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Recently, sterilization due to the ultraviolet rays is popularized in place of the polluted water sterilization by chlorine addition which has a bad influence on the ecosystem in the lower reaches of the river. We developed the electrode-less lamp device of the long life, big output which met such use a little in front. The examination to decline was done in that development reducing the voltage across to an exciting coil to prevent the phenomenon for a surface that to turn black from the time when a lamp was early. We improved the phenomenon which turned black in the early time of the surface of the lamp, and learned to provide a long life lamp as that result.

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Electrodeless UV lamp is used underwater. Since the inside of the UV lamp enclosure arranged underwater is exposed by an ultraviolet ray, ozone, and high temperature, a resonance circuit cannot be prepared. Therefore, you have to carry out the direct file of the underwater wiring to an exciting coil of UV lamp. You have to make below into 150 [V] voltage which joins underwater wiring for the safety to people. Therefore, we developed the lamp circumference circuit.

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We developed the high frequency power supply of the high output for the electrode-less lamp used for the sterilization of the polluted water. This power supply designed an electric power change circuit as a basic circuit 125W class to get big electric power in little space. This power supply realized an output circuit 500W class by composing the thing which became 4 parallel to basic circuits by using combiner circuit. Moreover, a special electric elements to use for the high frequency is unnecessary, and the use of the general-purpose elements becomes possible. It disperses, and it can radiate heat by this composition the loss of each circuit. Moreover, a special electric elements to use for the high frequency is unnecessary, and the use of the general-purpose elements becomes possible. The favorable 2.6MHz power supply of the 500W class could be put to practical use in the performance and the cost as a result of this development.

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We developed the control circuit of a high frequency power supply as equipment used for sterilization in sewage. Electrodeless UV Lamp is used for this equipment. We connected Electrodeless UV Lamp with the high frequency power supply using the coaxial cable. Since a coaxial cable existed, the control circuit performed frequency control by PLL. In such control, the coaxial cable discovered the length which operates safely. Consequently, Electrodeless UV System has secured high reliability. And very convenient equipment was able to be done.

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So far, incandescent lamp and halogen lamp have been commonly used in stage and TV studio lighting, while nowadays, in terms of efficiency, energy consumption, and heat generation, fluorescent lighting of high frequency is worth noticing in this application. Observing this situation, we have studied the difference between a two-wire system and a four-wire system for electronic ballast dimming control system for fluorescent lighting. The former regulates output of lighting equipment through phase control of power source by dimming signal, and the latter regulates output of lighting through changing oscillation frequency of lighting equipment by dimming signal, not controlling power source.
1) Two-wire system requires only two wires, while falls behind in following respects; increase of distortion factor in dimming operation, as a result, high noise, higher harmonic distortion. In four-wire system, power source always represents nearly a sine wave, high power factor, lower input current, little voltage drop in wiring, low noise, and higher harmonic distortion in little.....A fine electric installation. In sending dimming signal by a remote control system, it is possible to do without a convergence dimmer.
2) Two-wire system is liable to fluctuate in intensity of illumination with power fluctuation, is likely to flicker, and lacks for stability in dimming characteristic. Four-wire system excels in following respects; a stable intensity of illumination against power fluctuation, free from flicker, stability during dimming operation especially in deeper range, compatibility with flashing, and fulfilling lamp life. In conclusion, four-wire system is a much suitable dimming system for stage and TV studio lighting.

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In the lighting for high-speed photographing in TV and photo studios, it used to be a common practice to employ short are metal halide lamp of high efficiency and high color rendering competency in a flicker-free ballast at several hundreds of frequency rectangular wave.
We have newly developed a compact fluorescent lamp in “U” shape, exclusively for high frequency application. With this lamp, we also developed a new fixture “FHP 105 × 6 lamps”, also in compact size and yet performs in lighting output nearly equal to HMI luminaire. Mentioned below is the comparison between the performances in high-speed photographing with conventional lighting fixture and our new one.
1) Result of basic operation and high-speed photographing.
a) Short arc metal halide lamp.
Generates anode oscillation at re-ignition of 120Hz × 2 cycle.
Eventually generates flickering in high-speed photographing.
b) High frequency fluorescent lamp (45kHz).
Complete and smooth envelope wave without ripple.
Much suitable for high-speed photographing.
2) Conclusion.
Our newly developed fixture is superior to conventional short arc metal halide fixture in high-speed photographing. Furthermore, from the viewpoints of luminous flux, lamp consumption rate, heat generation, and lamp life period, this is an suitable fixture for lighting in TV studio and photo studios.

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We have fabricated a new filter using two different liquid crystal devices, which decrease and increase color temperature of transmitted light, and confirmed the basic operation of a color-temperature controllable luminaire using the filter and a xenon lamp with flat radiation spectrum. The two liquid crystal devices containing dichroic dyes individually absorb short- and long-wavelength visible light. By driving the devices individually, color temperature of illuminated light was continuously varied from 3800K to 8200K.

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Tunnel lighting is one of the traffic safety installation. Until now, a critical object to determine the visibility was specified to define of the road surface luminance for ensuring its visibility as a “lighting criteria”. However, in the case that either a running speed is fast or traffic is heavy, the visibility of preceding cars are considered as an important aspect. The visibility of preceding cars depends on a vertical illuminance behind them. It is necessary to define the vertical illuminance in relation to luminance of the access zone for entrance lighting and transmittance of the air for the interior lighting of tunnel. As a result, the relationship between the visibility of the preceding cars and the vertical illuminance was under study for both the entrance lighting and the interior lighting of tunnel.

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