It has been reported in a number of investigations that the subjective brightness of object colors is affected by changing the color rendering properties of lighting sources. However, the paucity of reports on various illuminance levels promoted us to investigate it. The subjective experiment was done for 15 test color chips under various illuminance levels covering 1280 to 1 lx. We used reference standard type cool white fluorescent lamp and six kinds test fluorescent lamps. The results show that the subjective brightness of object colors in the photopic range is effected by the increase of light saturation on the color chips by changing the type of fluorescent tubes. it did not show any change in the mesopic range.
Temperature profiles of plasmas in microwave discharge lamps dosed with mercury and iodine were measured on the assumption of local thermal equilibrium in consideration of plasma's asymmetry. The result indicated as follows:(1) The plasma temperature was almostly kept constant in the region from the center part near the wall of lamps.(2) The temperature decreased as the quantity of iodine increased. Then the resonance line shape of Hg 253. 7 nm was calculated from the temperature profiles. The calculated result was in relatively good agreement with the measured one.
An empirical formula was derived to express the results of conspicuity of colors determined experimentally in the previous report with 12 different colored charts observed at illuminance levels covering the range from 0. dl to 1000 lx. The formula is in principle based on the CIE 1976 L*a*b*color space and the theoretical conspicuity was defined as the distance in the space between the colored chart and the background. The formula expressed the conspicuity fairly well when the color space was modified such that its positive a* and b* values were multiplied by factors 3.0 and 0.1, respectively, and L* was expressed by a linear equation of LR* and Lc* calculated by using V'(λ) and y10 (λ).
High frequency operation of HID lamps causes acoustic resonance phenomenon, and several countermeasures to avoid it have been studied and reported. We focusing our attention to the balance of stable frequency and destabilizing frequency, experimented to find on what condition the arc is kept stable. We reached a result that even if some arc destabilizing frequency exists in the lamp current, an unstable condition will not grow so long as its ratio is small enough. We proposed the rectangular waveform operating method as a concrete operation circuit to apply this experiment result to actual use. We have found good characteristics in its operation, when applied to a 70W metal halide lamp. Here, we report our study on it.
The possibility of realizing daylight simulators satisfying the conditions specified in JIS Z 8720-1983 and Publication CIE No.51, with line spectrum illuminants composed of several monochromatic radiations (lines), was examined by a nonlinear programming technique. It was found possible to realize sinulators satisfying: (1) the condition of a visible range metamerism index MIuv ≤ 0.5 (CIELAB10) with 5 spectral lines, (2) the condition of an ultraviolet range metamerism index MIuv ≤ 1 (CIELAB10) with 3 lines, (3) both MIuv ≤ 0.5 and MIuv ≤ 1, while the general color rendering index Ra is not sufficietly high, with 6 lines, (4) Ra ≤s 95 (CIE 2nd Edition), while MIuv is not sufficietly good, with 5 lines, and (5) MIuv ≤ 0.5, MIuv ≤ 1 and Ra ≥ 95 with 7 lines. (6) Six lines are necessary to realize both MIuv ≤ 0.5 and Ra ≥ 95, in contrast with 5 lines in cases (1) and (4). These results show that the general color rendering index is a different measure from the metamerism index, and useful to supplement the latter for the assessment of daylight simulators. However, it is suggested that daylight simulators in eithr case (5) or (6) are insufficient to reproduce the color appearance of chromatic fluorescent objects excited by visible range radiation under a natural daylight illuminant.
Change of spectral sensitivities for mesopic vision was investigated under both the fluorescent illuminant and the natural twilight using a Lagorio's color chart made up of 24 different color strips inserted in between 29 step gray scales. On each color strip of the Lagorio's color chart, there is a minimally distinct border (MDB) between the color strip and the adjacent gray scale. The MDBs appeared in 24 color strips make up an envelope curve, which we call the MDB curve, on the Lagorio's color chart. The MDB curves were determined at the various illuminance levels by three 'observers. The experimental results from all observers showed that the luminous efficiencies for red color decreased with the decreasing of illuminance. The dependence of the luminous efficiencies for the other color on the illuminance change was different from observer to observer. Finally, an algorithm to estimate the spectral luminous efficiency function from the MDB curves observed on the Lagorio's color chart was discussed.
Absorption and penetration depth of infra-red radiation covering 2.5-25 micro-meter wave length have been established successfully in spectrographic way for city water by means of transmittance measurements and precise analyses of multi-reflection effects in the media. The view point of this paper is based on infra-red radiation heating. Special references are made to interference effects caused by forward and successively refiected backward waves in the tested media say, water. The interference affects transmittance measurements for some cases and doesn't for the other cases. Their separation is clearly described in the analyses and in the measured results too.
Apparent hue of the road traffic light signals was investigated employing the colour naming method in the daytime, at dusk and in the nighttime. Five subjects with normal colour vision participated inthis experiment. The recommended colour boundaries in the chromaticity diagram for the traffic light signals in japan are different from the CIE recommendation especially for the green signals. The results showed that apparent hue of the green traffic light signals ranged from greenish-blue to yellowish-green and considerable number of signals deviated from the CIE recommendation. Hue shift ofthe green traffic light signals at dusk and in the nighttime was also pointed out, that is, blue and white components of the green light signals increased considerably in the mesopic and scotopic visual environments. This suggests that apparent hue of the traffic light signals changes according to the adaptation levels of car driver's visual systems. The green lightsignals in the future were considered from the results of this experiment.