A research to define the preferable conditions of important lighting factors was carried out to develop a selection method of an appropriate light source for the design of comfortable mirror lighting. Such a light source would be helpful for women to apply makeup. Illuminance and color temperature were used in this study as important lighting factors for the mirror lighting. This paper describes two stages. In the first stage, the results of a detailed questionnaire of the acts performed when applying makeup clarified that these acts had different features depending on the time of day. In the second step, the lighting conditions that changed the brightness and color temperature were shown to observers for a range of practical mirror lighting techniques. The observers evaluated their psychological preference of various lighting conditions for applying makeup in the morning and at night. The results of this experiment were that, for makeup in the morning, observers had a significant preference for 5000K over 3000K and, for makeup at night, there was not significant difference. Therefore, a light source of 5000K is more appropriate than 3000K for the design of mirror lighting for the application of makeup in the morning.
To estimate the total revealing power of tunnel interior lighting for conditions of a specific observation distance and transmittance of the air, we investigated the relationship between road surface luminance and luminance contrast to achieve a correct perception rate of 75% (the critical luminance contrast) with silhouette vision and reversed silhouette vision. First, the relationship between the road surface luminance and the luminance contrast was derived in an experiment that used computer graphics (CG) for the visual angle of a range from 2.8 to 8.9 min under a clean atmosphere. Second, to determine the influence on visibility caused by the decrease in the transmittance of the air by soot and dust, we derived their relationship using a theoretical calculation for more than 50% of the transmittance of the air. These results agreed with those derived in field experiments.
A charge-pump inverter circuit is useful for an induction-coil type electrodeless lamp system, and the input AC current harmonics can be reduced by using an additional diode and a small capacitance. However, the circuit operation is too complicated to understand because of the correlation between the load characteristics of the electrodeless lamp and the involved resonant circuits. This paper analyzes the circuit operation of this inverter circuit and derives some equations that are effective for improving the input AC current waveform near the zero-crossing points of the source voltage. Furthermore, two simplified equivalent models for the involved resonant circuits were assumed for an optimal design of the circuit parameters. The analytical waveforms were experimentally verified, and the input-current harmonics were reduced by the optimized circuit parameters so as to meet the IEC class C regulation.
A method of calibrating low-intensity spectral irradiance using a mesh attenuator and a 500-W spectral irradiance standard lamp has been developed. The intensity of the lamp's irradiance is the same as that of a 20-W spectral irradiance standard lamp. The photometric value of the 500-W lamp stabilizes (±0.04%) within 15 min. of being turned on. In testing, the reproducibility of the photometric value for the mesh attenuator and detector setting was ±0.07%. The stray light under indoor illuminant was under 0.002% of the photometric value. The uncertainty of this calibration system was less than when using a 20-W spectral irradiance standard lamp.