Recently, miniature HID lamps have been developed and used for the indoor illumination in offices and stores. The ballast for the lamps is required to be smaller size, lighter weight and moreover excellent functions such as dimming, free from the source voltage variation and good controllability. If a dynamic simulation model of the HID lamps is given, it is very useful for the development and design of the such ballasts. In this paper, a simulation model of metal halide lamps is proposed with the state variable equation method based on the electric conductivity of plasma in the bulb. The equations are consist of the state variables such as mercury and halide additive quantity, conductivity of plasma, voltage and current of operating circuit and temperature of the lamp, etc. The calculated results of an 100 W metal halide lamp show comparatively good agreement with the experimental results at the lamp starting and the source voltage variation.
It is important to create preferable atmosphere of luminous environment as well as to satisfy visibility of visual tasks on a working plane such as desk tops, to make comfortable office lighting. To make preferable luminous atmosphere, it is required to achieve preferable luminous balance between main surfaces such as visual tasks and other room surfaces. Series of experiments with subjective appraisals were carried out to clear preferable range of luminous balance in the office room. At first in this report, preferable illuminance of the front wall related to the illuminance of the visual task on the desk is reported. Results are as follows: (1) Optimum wall illuminance Ew is given in the following experimental formula. log Ew=(0.27logr+0.73) log ED-1.llogr+0.43 Where ED: illuminance on the desk r: reflectance of the front wall (2) For the guide of a usual lighting design, permissible range of wall illuminance is found to be 320-440 lx, when illuminance on the desk is choosen freely or varied as a design between 500-1000 lx, and also wall reflectance is choosen freely between recommended range of 0.3-0.8. Here “permissible range” means not necessary optimum but in between both limits of upper and lower and is regarded as to be recommended. This results may be widely applicable to a comfortable lighting design of a usual office room.
The brightness for 12 test color chips was investigated under various illuminance levels covering 0.01 to 3000 lx. The experimental method was to match the brightness of test stimuli of color chips with a gray scale and to express the brightness by the equivalent lightness of the gray scale. The test stimuli were presented in a foveal 10° and 2° fields. Gray background of value N6 was used. The experimental results showed that the equivalent lightness for the red test col or chip decreased with the decreasing of illuminance. The equivalent lightness for the blue test color chip decreased with the decreasing of illuminance in the photopic range, but it increased with the decreasing of illuminance in the mesopic range. The equivalent lightness for the yellow test color chip did not change in the photopic range, but it decreased with the decreasing of illuminance in the mesopic range. The green test color chip did not show any change in its equivalent lightness. To explain this phenomenon, a formula was proposed by three functions, the rod achromatic channels, the cone achromatic channels and the cone chromatic channels for the equivalent lightness under various illuminance levels.
Lighting for streets should be designed in such a way that pedestrians on the street at night are able to identify the general characteristics of “other” persons still some distance away on the road. The illuminance level to be provided has been investigated experimentally in the laboratory by utilizing a lighting simulator. In the experiments, observations were repeated by 3 observers, 10 times each, for 30 different lighting conditions. As a result, a value of 2 lux for the vertical illuminance on the “other” person's face has been obtained as the minimum value that allows pedestrians to identify “other” persons at a distance of 4 metres (whether he, `she is an acquaitance or a stranger).
For the power control method of discharge lamp by electronic ballasts, the impedance variation with frequency changing can be thought. But as the frequency increased the swiching loss should be larger and the circuit efficiency becomes decrease. If zero voltage or zero current switching is done on the semiconductor devices, the losses may be decrease. This paper describes a high efficiency HID lamp operating circuit which has a high frequency inverter with an equivalent variable capacitance controlled by means of “ON TIME CONTROL METHOD”. The operational characteristics of the circuit are analyzed by simulation, and it is clarified a region of the circuit constants to suit for HID lamp operation. The experiment of 100 W metal halide lamp based on above results shows the circuit efficiency is about 80 %, and the variation of the circuit efficiency bounded within 10 % at controlling the output power from 100 % to 60 %.
The purpose of this paper is to consider the effect of CRT display image characteristics upon permissible luminance of reflected images of light source. In experiment 1 subjects were asked to adjust the luminance of disturbing light source on permitted luminance. The results showed that permissible luminance of disturbing reflections on the positive polarity display (dark character) was about three times higher than on the negative polarity display (light character). In experiment 2 subjects were asked to count the number of specific character in the displayed textual material containg disturbing reflection. The results showed that no significant differences in the effect of disturbing reflections on visual performance can be attributed to display polarity.
Traffic signal colors have been measured by a physical color measurement method and a appraisal color naming method for comparison of the both methods. Angles subtended between the visual line and a traffic signal lamp axis were changed to make color variation. For reference color chips were also measured. Four subjects were used in the appraisal experiment. As a results, it is clarified that appraisal color naming method has a good correlation with the physical color measurement method. Further, It is assumed that subjects decided the hue of a signal lamp to depend on the color of brighter and center part of the lamp surface. Moreover, effect of lamp voltage variation was measured. And difference between the chromaticities measured in a dark room and outdoor, were presented.
It is much simpler and more precise to obtain a configulation factor from the illuminance of calculating points than from the area measurements of the barrel-shaped distorting figure by the orthographic projection. There are three methods for calculating the illuminance of the calculating points for the basis of the configulation factor:(a) to calculate directly from the value of the coordinates on the inclined surface, (b) to calculate the coordinates of the via-perspective figure obtained from the dimentions of the inclined skylight, (c) to convert the angles measured by the transit into the coordinates of the via-perspective figure. The operating procedure in the modified integration formula, when calculating the illuminance of the flat surface source in terms of the via-perspective figure, has been altered in accordance with its computerization. When as above-mentioned calculating to obta in with a mode of seven-figures, which is commonly used in the personal computer, there possibly happens a great miscalculation under a certain condition. Therefore, the cause and precaution against this miscalculation will be described in the basic program.