TOP / Publications / Journal of Light & Visual Environment (JLVE) / Volume 30 Number 3, December, 2006
The Effect of Measurement Area on Modeling UVR Dose to the Inner Canthus
B. BIRT, I. COWLING and S. COYNE
117
Engineering Daylight into Commercial Buildings
G. ISOARDI, I. COWLING and S. COYNE
122
Analysis and Design of Power Factor Pre-Regulator Based on a Symmetrical Charge Pump Circuit Applied to Electronic Ballast
M. LAZCANO O., R. RAMOS A., R. SANHUEZA R., L. RODRIGUEZ R. and D. A. RUIZ-CABALLERO
130
Indirect Lighting System with Luminaire Installed on Uppermost Part of the Wall to Achieve both Visibility and Energy Saving Performance
S. FUJITA, Y. YASUOKA, T. MIZUNO, S. HAMAZAKI, M. NIKAIDO and K. IKEDA
137
Attempt to Predict Utilization Factors on Working Plane within Shadow under Task Ambient Lighting
A. UCHIDA and Y. OHTANI
148
Effective Intensity of Coloured Monochromatic Flashing Light
K. IKEDA and M. NAKAYAMA
156
Design and Development of an LED-Artificial Sunlight Source System Prototype Capable of Controlling Rela-tive Spectral Power Distribution
K. FUJIWARA and T. SAWADA
170
Developing White LED Lighting Systems and Its Technological Roadmap in Japan
T. TAGUCHI
177
People are exposed to varying amounts of UVR throughout their life from both natural and artificial light sources. The dose and rate of UVR exposure required for the formation of non-melanoma skin cancers is inconclusive. Certain regions on the face appear to exhibit a high rate of occurrence of Basal Cell Carcinomas (BCCs) in relation to the perceived dose of UVR. One of these regions is the inner canthus located on the medial side of the eye. The inner canthus appears to be well protected from large direct doses of ultraviolet radiation (UVR). Facial features such as eyelids, eye brow ridge, nasal bridge and cheek, combine to limit the solid angle of the field of view of the inner canthus to UVR from overhead sources. To explain the unexpected high rate of BCCs it is hypothesized that a percentage of the radiation incident on the eye is reflected onto the inner canthus. This paper showed that a portion of the radiation incident onto the eye was reflected towards the inner canthus. The percentage increase above the direct dose was only 2% across the whole region. As the detector elements decrease in size it is observed on a cellular level that some of the cells dose increased by 30% when the reflections were considered.
KEYWORDS : ultraviolet radiation, basal cell carcinomas, reflections, eye, inner canthus
The daylighting of commercial buildings offers the opportunity to reduce energy consumption and improve occupant appraisal of the quality of their interior environment. The focus of this paper is the assessment of a light-redirecting device designed for use in a passive daylighting system for conventional, high-rise building façades. This paper presents an introduction to how performance parameters can be defined and performance analysis conducted at the design stage of this daylighting device using ray tracing software. The device is judged on its potential to redistribute light throughout the depth of a typical room without causing discomfort glare to occupants. A proposed definition of optimal device performance, derived using geometric considerations, is also presented.
KEYWORDS : daylighting, Light-redirecting device
This paper presents the analysis and design of a power factor pre-regulator based on a symmetrical charge pump circuit applied to electronic ballast. The operation stages of the circuit are analyzed and its main design equations are obtained. Simulation and experimental results are presented in order to show the design methodology feasibility.
KEYWORDS : power factor pre-regulator, symmetrical charge pump, electronic ballast
In this study, lighting environment under wall-installed indirect lighting method with high diffusive-reflective ceiling paint is examined. The authors studied desktop illuminance and vertical illuminance (height: 1200mm) in this lighting environment of the room(4000 x 4000 x 2700h mm) . The average desktop illuminance is 844 lx (1.06 times greater than that under direct lighting method (employing luminaire of white reflector with white louver) with ready-made ceiling paint) , and the average vertical illuminance is 560 lx (1.16 times greater than that under direct lighting method with ready-made ceiling paint). As to the appearance of photogravure paper on the desktop, slight reflection of ceiling(immediate area of the luminaire, luminance: 1990-2150 cd/m2) onto the photogravure paper is observed, but there is no difficulty in terms of visibility at any part of the letters, figures or photo images. Human faces and inner walls in the room appears to be brighter than under direct lighting method with ready-made ceiling paint.
KEYWORDS : indirect lighting, photogravure paper, visibility, energy-saving
The number of luminaires in an office in the field of lighting design is usually determined with the lumen method, which uses utilization factors. These factors are calculated by luminous flux incident on the working plane to that irradiated from the light source, assuming a non-obstructed room. Lighting design techniques with the lumen method are very useful if they are applied to an office with fixtures and task ambient lighting, which is a combination of local-lighting and general-lighting systems. We applied lighting design to a working plane within shadow under task ambient lighting, and paid attention to utilization factors with the lumen method. That is, we evaluated the correction coefficients where the utilization factors in setting up fixtures and a shadow caster (i.e., a globe the size of a human head) could easily be predicted by multiplying the utilization factors for a non-obstructed office and the correction coefficients. The utilization factors using the lumen method on the working plane within shadow for ambient light sources and a task light source were first examined based on results derived from illuminance calculations using the Monte Carlo method that treats notion of the luminous flux as a set of numerous particles. The validity of correction coefficients used to calculate utilization factors within shadow under task ambient lighting was then evaluated. As a result, utilization factors within shadow can be predicted by simply multiplying them by the correction coefficients in non-obstructed rooms with ambient light sources or from direct components without a shadow caster for a task light source.
KEYWORDS : task ambient lighting, shadow, lumen method, utilization factor, correction coefficient
Flashing lights are used for visual guidance lights for aircraft navigation and traffic signs for the aid of maritime transportation, as they are more conspicuous and distinguishable than fixed lights. The brightness of a flashing light is expressed in terms of the luminous intensity of a steady light that is perceived as the same brightness. Such luminous intensity is called geffective intensityh. A mathematical method to calculate geffective intensityh was proposed by Blondel and Rey and analyzed by Douglas. However, this formula is an approximation formula based on the data obtained from a visual experiment conducted under a limited condition, namely, threshold level white flashing light observed in a dark background. In this study, a flashing light generator by which white as well as monochromatic flashing lights of 8 wavelengths (430, 470, 490, 510, 550, 580, 600 and 630 [nm]) with 34 different flash durations (from 100 [µs] to 1 [s]) is prepared. A visual experiment to evaluate the perceived effective intensity of flashing lights in comparison to reference steady light is conducted using this generator, while generating flashing lights of three perceived brightness levels (gthresholdh, gminimumh and goptimumh) under three different background luminance conditions (0, 1 and 10 [cd/m2]). The objective of this study is to propose a new and practical formula to estimate the effective intensity, while comparing the perceived effective intensity obtained from the experiment (Ie) with the estimated effective intensity obtained by Blondel and Reyfs formula (Is) and analyzing the characteristics of the brightness perception of flashing lights in terms of time. Upon analyzing the results, the following is clarified: a) Ie gradually becomes greater than Is as the flash duration decreases from 1 [ms]; b) in the case where both the brightness level of the flashing light and the background luminance are high, the ratio (Ie/Is) is not constant, but a local minimum appears between the flash duration of 0.003 and 0.010 [s] and a conspicuous local maximum appears between 0.03 and 0.10 [s]; and c) flash durations that provide the local maximum and local minimum are relatively short for white, blue and yellow flashing lights and long for red and green flashing lights. A new formula to estimate the effective intensity is created upon considering the photochemical response characteristics of the receptor of the visual system and characteristics of the sensitivity suppression caused by the feedback effect of the nervous system, both in terms of time. Further, it is verified that the estimated effective intensity calculated by the new formula (It) properly approximates to the perceived effective intensity.
KEYWORDS : flashing light, monochromatic light, effective intensity, navigation light, visual signal, colour
An artificial sunlight source system that is able to produce a spectral power distribution (SPD) approximating ground level sunlight (GLS) as well as arbitrarily modified SPDs would facilitate the investigation of living-organism responses in various light environments. A prototype of a light emitting diode (LED)-artificial sunlight source system was designed as a first step towards the development of such a system. The LED-artificial sunlight source system produces a relative SPD (composition of wavelengths) approximating GLS in a wavelength range of 400-900 nm by applying different voltages to LEDs with 32 different peak wavelengths (395 to 910 nm). The irradiance of the system is as low as less than one-tenth of GLS. In addition, the system can produce time-varying light in any order at time intervals greater than one second by preparing a series of sets of applying different voltages to LEDs. The configuration of the LED-artificial sunlight source system, the method used to produce the desired relative SPDs, and testing of the system are described herein. We also discuss necessary improvements to achieve an artificial sunlight source system that can produce an SPD approximating GLS.
KEYWORDS : artificial light, LED, spectral irradiance, spectral power distribution, sunlight
This article is concerned with a summary of the future prospect of white light-emitting diode (LED) lighting technologies that have been heralded in gwhite LED lighting environmenth special committee in the Illuminating Engineering Institute of Japan since 2002. The properties of various high-efficiency LEDs that are currently commercialized for practical application are firstly described. Since the characteristic feature of white LED lighting in terms of light distribution are strongly dependent on the light source design, we thus designate to construct new concept of light quality which takes into consideration both product design and lighting design. It is expected that the transition from traditional lighting is likely to progress from around 2010 in comparison with several kinds of incandescent bulbs and fluorescent lamps. Finally, the technological roadmap has been disclosed on the basis of our discussion.
KEYWORDS : white LED, lighting, system, design, roadmap