We developed an experimental plant factory equipped with fluorescent lamps to illuminate plants closely and the inside wall coated with highly reflectable paint to use reflected light effectively (close illumination method). In this paper, saving degree of lamp energy of the close illumination method on lettuce cultivation was experimentally and theoretically investigated by employing this plant factory. (1) The mean photon density on the cultivation panel (area of 12 m2) was as highas 650μEm-2S-1, when 42 fluorescent lamp S (110W) were installed 30 cm above the surface of cultivation panel to illuminate plants. (2) The coefficient of utilization (U), which indicates the light utilization efficiency in this cultivation room of this plant factory, was about 1.7. The measured value of U is well coincide to the value calculated by Moon's equation, and was nearly 2.5 times higher than high pressure sodium lamps installed about 80 cm above the cultivation panel. (3) The electric energy consumption for lighting and total electric power consumption for the production of lettuce (75gfresh weight) was about 1.1 kwh and 2.5kwh respectively. Thus, the electric energy consumption for lighting was about half that of conventional high pressure sodium lamps. On the other hand, the lighting power consumption for the production of seedlings weighing about lOg and 0.2g was about 0.3 kwh and 0.06kwh, respectively.
Recently, computer graphics such as “ray tracing” has been often used for various lighting systems, in order to estimate lighting system designs. However, in a conventional ray tracing method, it was difficult to deal with diffusely reflected light. Therefore, there was a problem that synthesized images were more or less unnatunal. To overcome the problem, a new technique such as radiosity method or bidirectional ray tracing method has been proposed. By one of the above method, diffusely reflected light can be considered in the computer graphics. On the other hand, there are a few studies which examine quantitatively the influence on color change caused by the inter-eflection. In the present paper, Monte Carlo simulation was used for the calculation of spectral luminous exitance in an interior of model room with infinite length. The color of a ceiling and a floor was assumed to be white, and that of walls was assumed to be white, red or blue. Then we study the difference of spectral luminous exitance among these models. The results show that the spectral luminous exitance of a ceiling and a floor changed together with color change of a wall, even if the same light source was used.
Long-term lumen maintenance of high-load fluorescent lamps has been investigated using 3-band rare earth phosphors. The contact electric charging tendecy of a phosphor was systematically varied by depositing colloids on the phospor particle surfaces. For every phosphor system tested, the maintenance showed a maximum at a certain value in the charging tendency where the amount of mercury oxide adsorbed on the phosphor was minimum. On the other hand, the depreciation of the phosphors themselves did not depend on the charging tendency. Furthermore, the charging tendency of mercury oxide was found to lie near that for maximum maintenance. From these results, it has been concluded that the difference in charging tendency between mercury oxide and a phosphor governs mercury oxide adsorption on the phosphor; the amount of adsorbed mercury oxide becomes larger with increase in the difference causing significant fluorescent lamp depreciation.
A daylighting calculation method for a domed stadium is presented. Based on this method, a computer program has been developed to predict illuminance distribution by daylight in a retractable domed stadium. Direct sunlight and skylight are considered as daylighting sources in this program. Skylight model is based on the C. I. E.(Commission Internationale de l'Eclairage) Overcast and Clear Sky functions. For the purpose of examine the accuracy of the prediction by the computer program, the calculations are compared with the scale model measurements. A retractable domed stadium was designed and the 1:200 scale model was made. Illuminance measurements were carried out by setting the scale model under an artificial sky. The measured values were compared with the predicted values for the same conditions simulated by the computer program. As for this stadium, the predicted values agreed well with the measured values.
This paper is concerned with the important visual variables that determine legibility of computer-controlled flat panel displays (FPDs). Thirty-five FPDs (29 LCDs, 3 PDPs, 2 ELDs, and 1 VFD) and five CRTs are analysed in relation to the following photometric properties: (1) Luminance and contrast ratio.(2) Specular reflectance.(3) Viewing angle dependency of contrast. Special equipments are developed and standardized conditions are applied to the measurements. For each visual variable the recommended level is determined on the basis of subjective evaluations and is compared with the presently used levels for that variable on several different displays. It can be concluded that manufacturers should pay more attention to human factors when designing displays.
This paper describes an application of finite element procedure for illuminance distribution analysis. The purpose of this paper is to study a radiative characteristic of a semi-conductor laser and the treatment of obstructions. The illuminance distribution by computer simulation agrees with the result of mesurement.
Many workers claim to feel the visual fatigue caused by vigilance tasks. V erbal reports of the visual fatigue have not corresponded to results by ophthalmological and psychophysical testings. Our previous studies showed that temporal sensitivity in vision changed concomitant to the visual fatigue, and that the change of the sensitivity appeared in difference in dynamic range of responses obtained from threshold measurement and did not in the thresholds themselves. Based on the studies, a new fatigue testing method called as the duration method was developed and an apparatus for measuring the temporal sensitivity to the light was devised. In results of Exps. 1 and 2, an available condition for measurement of visual fatigue was found. In Exp. 3, under the available condition, effects of the three local lighting conditions were shown quantitatively in differences in the dynamic range. In this experiment three subjects performed writing-tasks in everyeight hours in each of the three conditions. Interday variations were counter balanced.