Quantitative measurements have been performed on the evolution and absorption of mercury from Zn-Hg fluorescent lamp amalgams. Thermogravimetric analysis (TGA) under atmospheric pressure and vacuum (1.4-1.6 torr) conditions has been employed to study mercury evolution from Zn-Hg amalgam spheres. Conditions for the accurate determination of total Hg content of single Zn-Hg amalgam spheres under linear temperature ramp and hold conditions have been determined. Isothermal TGA has been used to measure both the short-term and long-term evaporation rate of Hg from single Zn-Hg spheres. In a related experiment, the total weight loss on 1500 individual Zn-Hg spheres was measured and statistically analyzed. Finally, using a special fulcrum apparatus the reversible evolution and re-absorption of mercury from Zn-Hg spheres was studied and characterized under simulated lamp conditions.

A great number of various electronic compact fluorescent lamps (CFLs) have been developed in the whole world. Although most of them are globeless type, general consumers in Japan have not yet completely got used to the naked light tubes, and they also have a tendency to prefer brighter lamps. Thus, we have developed the 23W electronic CFL with a diffusive glass globe, which generates 1370 lm on 100V main supply and can be substituted for a 100W ball shaped incandescent lamp. In this paper, we explain the structure and the characteristics of this lamp, and also discuss some important technical issues which are the way to control the mercury vapor pressure by using amalgam and to keep safety at the end of life.

Measurements of the statistical starting time-lag T_s(s) of non-preheated electronic compact fluorescent lamps show that T_s increases with longer off-time before starting and also with a darker environment on starting. The initial electrons per second Q(1/s), which is inversely proportional to T_s, changes from 1.2 to 72 in the dark environment on starting. Initial electrons are obtained mainly from the oxide emitter of the electrodes, even if they are not pre-heated. A brief start requires a Q greater than 260. This is achieved by heating an electrode to only about 100 celsius.

An advanced method to detect the position of an unknown light source is proposed. In this method, photon bundles received at light receiving sensors are backward emitted to a light room according to the illuminance distribution at the light receiving sensors. A tentative position in subdivided cubic elements is first determined by the backward emission of photon bundles from sensors. Next, photon bundles are forward emitted from subdivided cubic elements, including cubic elements within a spatial range around the coordinates of the tentative cubic element. Photon bundles transmitted by photon emissions from the unknown light source and from the tentative light source are detected by light sensors and compared. When both illuminance values agree, the tentative light source is determined to be at the position of the unknown light source. Monte Carlo simulations are used to solve this kind of inverse problem in a light room calculation. To express the performance of the simulation method, the rate of spatial reduction of the light room is newly introduced. Monte Carlo simulation demonstrated that the advanced method of backward emission of photon bundles is very useful for detection of an unknown light source in a shorter computing time compared to the conventional method.

KEYWORDS: Detecting sensor, Unknown Light Source, Backward Emission, Forward Emission, Inverse Problem, Monte Carlo Simulation, Illuminance Distribution

We studied whether or not the glare evaluation system for outdoor facilities (CIE112-₁₉₉₄)¹⁾ can be applied to indoor sport facilities. Firstly we devised a method for obtaining "equivalent veiling luminance of environment (L_ve)", which was hard to measure in indoor facilities, based on the luminance distribution of photographs. We then analyzed the validity of the GR calculating formula +based on the results of glare evaluating experiments in four indoor facilities and data from various luinance measurements taken. In conclusion, we found that the GR calculating formula is applicable to indoor facilities without any modification, and that there was no significant differences in estimated GR values results when evaluating the equivalent veiling luminance of environment using the average luminance (illuminance) of the floor.

Brightness and lightness of achromatic surface colors were evaluated under various illuminance conditions in order to make a brightness scale that can be applied for all adaptation levels. A pair of gray scales made up of six gray color chips were presented in a test field and a reference field. Brightness as well as subjective lightness of the six test colors were evaluated using a gray scale in the reference field. Not only haploscopic and also binocular viewing conditions were employed. Furthermore, two comparison techniques¾a conventional direct comparison method and a newly developed cascade comparison method¾were used in the case of brightness criterion. Experimental results show that the perceived contrast decreased with decreasing Illuminance for the brightness criteria. The contrast compression for a cascade comparison was larger than that for a direct comparison. No contrast compression was obtained for the criterion of subjective lightness.

KEYWORDS : brightness, lightness, adaptation level, mesopic vision

A new Multi-Layer type full color LED, capable of mixing different luminous wavelengths to radiate many different colors of light (visible also from a short distance), at high levels of efficacy. Excellent luminous intensity, has been demonstrated by the prototype. Values of 35 cd white light have been achieved using multi-layered blue, red and green chips, at a current of 20 mA per chip.