Dimming of conventional metal halide lamps readily causes changes in the lamp's color, decreases its efficacy, and reduces its lifetime. Employing inductively coupled electrodeless discharge in mercury-free metal halide lamps led to less color change and greater efficacy in dimming. The correlated color temperature of optimally designed lamps, containing a dose of ScI3-NaI-SnI2 and Xenon gas in the arc tube, was changed by only 300K at the 30% dimming ratio. The general color rendering index (Ra) did not shift greatly and the lamp's efficacy could be kept at 89% of the rated wattage efficacy at 75% of the rated wattage (1/4 greater than the conventional result). It was possible to correct the color characteristics during dimming by adding new metal halides to the ScI3-NaI-SnI2 lamp, keeping improved dimming characteristics. It was possible to correct color deviation and Ra by adding suitable amounts of DyI3 or InI, though the lamp efficacy decreased by about 10% at the rated wattage. This has proved that the dimming performance of metal halide lamps can be improved by employing inductively coupled electrodeless discharge in optimally designed mercury-free metal halide lamps.
The culturing of micro-algae is important to the production of seeds for shellfish. We have developed an economical method of doing this that uses step-style light control to reduce the production cost, and appeared light environment of the culture chamber. The light intensity is increased 10% to 30% on the 3rd day (1.5×106cells·ml-1), from 30% to 60% on the 6th day (6.0×106cells·ml-1) and from 60% to 100% on the 9th day (1.4×107cells·ml-1) of cultivation. We cultivated P. lutheri using step-style light control in a 200-l chamber; the other factors were same as for conventional 100% stable light intensity cultivation. The dark zone of the chamber, which was less initially than 1μumol·m-2·s-1, increased with the cell density. It occupied 50% of the chamber at 1.5×107cells·ml-1 and 60% at 2.2×107cells·ml-1. The growth curve was identical to that for stable 100% light intensity. Then it is possible that the consumption of electrical power was 40% lower with step-style light control.
The illuminance characteristics of a next-generation energy-saving luminaire for street lighting is described. It consists of white-light-emitting diodes (LEDs) and a solar-cell and battery system. A prototype luminaire was constructed of two LED light sources, each of which with a total of 700 units of 10-cd-class white LEDs. The illuminance is normally 80lx. When a person approaches within 2 m of the luminaire, a pyroelectric motion-sensor senses the situation and the illuminance is increased to about 660 lx. This is about 50 times brighter than a white incandescent lamp. The luminous efficacy of the white LED array source was estimated to be approximately 451m/W at a forward-current of 1mA. Field testing showed that this white LED lighting system did not suffer serious deterioration in either it's brightness or electric circuit over a period of one year.
To clarify importance of personal adjustments with office lighting, authors interviewed 17 general office workers and 38 experts in lighting industry. We also conducted the experiments to quantify the effect that having the ability to change the illumination level themselves had on the workers' satisfaction and to distinguish between the effect resulting from “Control” and one from the change itself. The interviews showed that both the general office workers and the lighting designers perceived lighting adjustments as a key factor, while importance of the adjustment was not recognized so much. The experiments showed that evaluations of the luminous environment differed greatly depending on whether the evaluator was able to adjust the lighting level, while both the effect resulting from “Control” and one from the change in illumination level were slight.
Usillg both simulation and experiments, we investigated cause to ensure that the supply currellt in an electrical circuit with a common by-pass circuit can be kept approximately constant from start-up to reachillg steady state. In such circuit, the supply current can be distorted by about 2% when the power factor reaches 100%. We found that an approximately constant supply current can be achieved, thus making these circuits practical for usewith multiple high-pressure mercury discharge lamps, even when a larnp does not light.