We have established a visualization system for spatial illuminance, in order to visually recognize the three-dimensional luminous condition in a lighting space. It calculates illumination vector and mean spherical illuminance at every point on a regular grid, and displays them graphically with perspective. This paper describes the simulation and analysis of the luminous environment of a soccer ground and an interior, including the spherical presentation of mean spherical illuminance distribution, color contours of mean spherical illuminance distribution on a certain 2-D section, perspective display of pointing arrows, and isosurface of mean spherical illuminance. These readily understandable presentations enables us to lay the foundations for applying spatial illuminance to the analysis of lighting conditions.
In order to clarify the relationships among factors for evaluating complexions of Japanese women-their chromaticity coordinates and their color appearances under illuminations-, a series of experiments were conducted. The complexions of three female models were estimated under 40 kinds of illumination by the semantic differential method using 31 adjective pairs rated by 20observers. Evaluations of human complexions under the illuminations were determined by two main factors, “activeness” and “refinement”. The factor score for“activeness” correlated well with the color perception of “reddish-greenish” for human complexions under the illuminations.“Activeness” was generally rated higher as the complexions become more reddish. The factor score for“refinement” was highest when the human complexion was perceived to be slightly reddish. It became lower as the chormaticity coordinates of the human complexion under the illumination became further from that having the highest factor score.
We have compared differences in texture between computergraphics displays and the actual materials. We evaluated the appearance of 35 actual samples (building materials, exterior materials etc.) and 40 samples generated by computer graphics using the Semantic Differential method. Using Principal Component Analysis, we found that approximately 94% of appearance characteristics can be explained by five principal components. The appearance characteristics that can be described using the Phong model are the first principal component (gloss), aspects of the second principal component (density and weight), and the fourth principal component (clarity of appearance). The balance of the second principal component (density and weight) and the fifth principal component (metallic appearance), cannot be explained by the Phong model. Glossiness is proportional specular reflectance divided by diffuse reflectance and specular reflectance, and the cubicroot of the exponential variable representing the surface glossiness. These relationships show how texture changes with diffuse or specular reflectance, transmittance and the exponent representing the surface glossiness.
During D.C. operation of high-pressure sodium lamps, it has been experimentally found that cataphoresis does not occur when PNA>5.6I1a· L/d2+0.5, where PNA is the pressure of sodium [kPa], I1a is the lamp current [A], L is the distance between the pair of electrodes, and d is the diameter of the lamp bulb. Therefore, high-pressure sodium lamps with high color rendering do not exhibit cataphoresis, because they satisfy the above condition. However, high-pressure sodium lamps with high color rendering suffer from another problem the color temperature of the lamp is scattered for individual lamps of the same type. This problem can be solved by controlling the lamp voltage V1a and the lamp current I 1a so that a·V1a+b·I1a=constant, where a and b are constants. High-pressure sodium lamps with high color rendering operated under those conditions avoid cataphoresis and have no deviation in color temperature.
In order to find the electrical conditions for operating high-pressure sodium lamps with a constant correlated color temperature to get high color rendering from lamps of the same type having different correlated color temperatures, we conducted a set of experiments. We operated 150W lamps under various electrical conditions to determine the relationship between the correlated color temperature and the electric properties. Based on the results, we derived the following formula: Tcp=a·W1a+b· V1a+c, where Tcp is the correlated color temperature, W1a is the lamp power, Via is the lamp voltage, and a, b, and c are constants. This formula gives the electrical conditions of W1a and V1a for a specific value of Tcp. The same formula is also applicable to lamps of other wattages by changing the values of the constants a, b, and c. If the correlated color temperature of the lamp is limited to±150K by controlling these electrical conditions, the deviation of the lamp from the black body locus is preferable for vision. In the same manner, we derived Tcp=d· V1a+e· I1a+f, where Tcp is the correlated color temperature, V1a is the lamp voltage, I1a is the lamp current, and d, e, and f are constants. The sensing circuits for a specific value of Tcp can be the simple sensing circuits of V1a and I1a.
Effects of reflection properties of liquid-crystal displays (LCDs) on the reflected glare disturbances were investigated by subjective rating. We studied seven TFT-color LCDs and three CRT displays having different anti-reflection treatments. The specular reflection coefficients of these displays were measured for different source sizes. The disturbing reflections on these displays were subjectively rated to elucidate the relationship between the specular reflection coefficient and the reflected glare disturbance. The results indicated that the interrelation was most obvious (r2>0.9) for a 1-degree source between the specular reflection coefficient and the subjective rating of the glare disturbances from the overhead illuminations. Similarly the subjective ratings of reflected glare from a simulated window were estimated from the specular reflection coefficient for a 10-degree source size. These results have been incorporated into a model for predicting reflected glare disturbances.
In order to develop a thermal radiation detector that can be used as a reference to measure optical radiation power and the spectral responsivity of a radiation detector, we investigated gold-back radiation absorbers. The spectral responsivity of the thermal radiation detectors are determined by the optical and thermal properties of the absorbers. The thermal radiation detectors consist of polyvinylidene fluoride (PVDF) pyroelectric film with the absorbers. The gold-back is prepared by evaporating gold in an oxygen-free nitrogen atmosphere and deposited on the Al electrode of the PVDF pyroelectric film. The nitrogen pressure was varied from 0.5-3 torr and the surface density of the deposited gold-black was varied from 0.02-1mg/cm2. We found that a gold-black radiation absorber prepared by evaporating gold in a nitrogen pressure of 1.5 torr and depositing it to a thickness of 11μm, the gave the highest spectralpresponsivity, which was constant within 1% over a wavelength region of 200-600nm.
On the reduction of harmonic current in the lead type operating circuit for a high pressure mercury arc lamp, the discussion is carrried out by the simuration and the experiment. As to the lead type operating circuit with the bypass circuit from the middle of a ballast, a lamp is substituted with an equivalent conductanceG, and by solving the five-element simultaneous differential equations for lamp current 1, and others in relation to time by the computer operation according to Runge-Kutta-Gill method, and harmonic analysis is carried out on the voltage and current of respective elements. The most appropriate operating circuit is shown from the magnitude, the distortion factor of power source current and the peak factor of lamp current.