Road lighting is best known to have the potential to improve night-time safety. The vast majority of research studies have shown that the installation of road lighting has favourable effects on the number and severity of road collisions. In addition, some evidence suggests that current road lighting practices are over-lighting the roadway. Therefore, the rapidly growing concerns about energy consumption and its related costs will force further changes in road lighting technology and practice. To date, there have been no studies that investigated the association between current knowledge and the road lighting guidelines. This article reviews and discusses CIE road lighting guidelines for motorised traffic. It then provides current knowledge in the area of lighting motorised roads leading to possibilities for intelligent lighting control. Finally, suggestions for considering dimming of road lighting based on recent developments in science and technology are provided. The three recommended approaches, static road lighting, semi-dynamic lighting levels, and dynamic lighting levels, could save energy without compromising traffic safety.
We investigate the behaviour of a new-type daylighting system composed of concave and convex paraboloidal mirrors. This system realises converting parallel light into highly-dense parallel before passing through the focal point. It means that the system solves one of the significant problems in daylighting systems: heat problems. In this paper, we set up the theoretical model of our new-type daylighting system, check the model using the two-dimensional ray-tracing code, confirm the relation between simulated data and simulation resolutions, introduce convenient contour maps and three type performance indexes and estimate the performance of our system.
Recently, fluctuation is attracting widespread interest in lighting field. However, little attention has been paid to the effects of fluctuation with HRV during tasks on autonomic nervous systems and doing concentrate by lightings. This study is aimed at the physical and psychological effects of fluctuating illumination on HRV during various tasks by task and ambient lightings. The results suggested that a certain types of fluctuating illumination on HRV derived in concentration tends to promote relaxation and does not tend to restrict sleepiness based on circadian rhythms.
This study investigates the effect of blue light emitted by phosphor-converted white light-emitting diodes (LEDs) on people’s eye fatigue. We conducted an experiment in which participants performed a visual task under lighting conditions using a white LED (B-LED) in which blue light excites phosphors and white LEDs (V-LEDs) in which violet light excites two types of phosphors. One of the two V-LEDs had a spectral power distribution mimicking those of the sun (S-LED). During the experiment, we measured participants’ subjective eye fatigue, number of eye blinks, accommodation power and critical flicker frequency. The results of the subjective evaluation suggested that participants’ eye fatigue under the B-LED lighting was worse than under the S-LED or V-LED lighting. The results of the eyeblink and accommodation measurements suggested that participants’ eye fatigue under the B-LED lighting was worse than under the S-LED lighting. In the range of the white LEDs employed in our experiment, we found that participants’ eye fatigue under lighting conditions with a blue-light-excited white LED could be worse than under a violet-light-excited white LED. The results of the objective response measurements suggested that the fatigue of eye muscles is the principal factor causing subjective eye fatigue.
We evaluated the spectroscopic performance of an otoscope during otoscopic examinations using a headlight with an LED source. We used the mechanisms and the specifications of the objects measured with the otoscope and so on to evaluate the spectroscopic performance. Experimental equipment was built using the existing otoscope and headlight, and we demonstrated methods of measuring the spectral irradiance of the otoscope. We demonstrated methods of evaluating the spectroscopic performance using the spectral irradiance ratio and chromaticity by the measured spectral irradiance. We measured the spectral irradiance of the otoscope using the measuring methods. We found that the spectral irradiance distribution in the otoscope is greatly affected by the spectral distribution in the headlight source. We evaluated the spectroscopic performance of the otoscope using the evaluation methods. The spectroscopic performances of the reflected light onto the surface of, and the direct and reflected lights in, the otoscope differ and are affected by differences in shape, surface condition, length, and the diameter of the wide mouth. The spectroscopic performance of the direct and reflected lights in the otoscope is affected by differences in the diameter of a narrow mouth and the distance and angle between the otoscope and the headlight.