In the former paper (1985), “Flicker Luminance Ratio” (FLR), which is a ratio of two such average luminances of alternating light waves that is divided the respective wave duration, was proposed and confirmed to be most adequate as the index of sensation for such flicker waves that is induced at both end parts of a fluorescent lamp. The alternate different light waves are also periodic waves and the analysis with Fourier expansion can be applied for them. Then, the amplitudes and the amplitude modulation degrees comprised of fundamental wave, second and third harmonics wave were compared each other in terms of the correlation to actual subjective appraisal data. Furthermore those data of amplitudes and amplitude modulation degrees were compared with the above mentioned FLR. Results are as follows. (1) Among them, the amplitude of fundamental waves and the amplitude modulation degree of them have practically suffcient suitability. (2) FLR has higher correlation with subjective appraisal than above two. FLR is confirmed to have practically sufficient suitability as the index for flicker sensation from alternate different light waves in peripheral visual field.
This research relates to the harmonic characteristics of the continuous dimmer circuit for the fluorescent lamp. The research has been conducted in the following sequence. When the firing angles caused by the TRIAC are varied on the main voltage of the input terminal, Fourier series are developed on the voltage and current of a distorted wave at each element of the continuous dimmer circuit. And with the Fourier expantion, each harmonic character at each element of the continuous dimmer circuit is theoretically obtained, and the experiment is performed to demonstrate it. (1) From the voltage and current of a distorted wave at each element of the continuous dimmer circuit, the vector diagram is obtained for the harmonic of each firing angle, and their characteristics are clarified. (2) From the voltage and current of a distorted wave at each element of the continuous dimmer circuit, the impedance (i.e. its resistance and reactance component) is obtained for the harmonic of each firing angle, and their characteristics are clarified. (3) From the voltage and current of a distorted wave at each element of the continuous dimmer circuit, the equivalent circuit is obtained for each harmonic, and their characteristics are clarified.
Conspicuities of 12 colored charts were measured at six illuminance levels covering photopic, mesopic and scotopic regions. Grey background of six different values was used. An experimental method was used in which subjects picked up the charts one after another according to the conspicuity. The most clear change in the conspicuity was found for the chart 8R4/14 when it was observed on the N1 background. It was the most conspicuous color out of 12 colors at the illuminance of 1000 lx, but it was the least conspicuous at 0.01 lx. The contrary characterisitcs was observed in the blue colors. These findings were well explained by the Purkinje shift. The illuminance levels where the Purkinje shift took place differed rather greatly among subjects. It was between 100 and 10 lx in one subject but it was between 1 and 0.1 lx in others. The difference was explained by the difference in the Purkinje shift of the second kind.
This paper is concerned with a new method for measuring luminous intensity of a tungsten incandescent lamp. Absolute spectral sensitivity of a silicon photodiode was determined by the self-calibration technique developed by the NBS, and a V (λ) Correction filter and a diaphragm of known opening area combined with this photodiode were used for the photometer. Uncertainty of the measurement was estimated to be about 1%, and this method was considered to be a satisfactory practical method for the luminous intensity measurement without using a photometric standard source.
When HID lamp is operated at high frequencies (several kHz to 100 kHz), arc instability caused by accoustic resonance occurs. Especially in metal-halide lamp, the frequency regions for the stable operation are narrow and vary with the operating condition. Therefore high frequency operation of the metal-halide lamp with fixed frequency is difficult. In this paper, a microcomputer (CPU and memories) is used to detect the instability of discharge and control the operating frequency. A CPU monitors the lamp voltage for detecting the instability. When the discharge is unstable, the frequency is swept to search the frequncy region of stable discharge. If the stable region is found, the value of the frequency at the lower edge of the region (f1) and that at the upper edge (f2) are stored in the memory (RAM). Then the frequency is set at the average value of f1 and f2, and the lamp operates in the middle in the frequency region of stable discharge. If the discharge become unstable, the above process is repeated to search the region of stable discharge. This procedure has an advantage that the interference with communication system is little compared with the operation with frequency modulation or square wave.
For security and safety reasons, it is important to konw the number of people entering and exiting a building, as well as the distribution of people on particular floors. Basically, the number and the direction of pedestrians can be measured by monitoring a pair of parallel lines across the pedestrian way. The authors have developed a bidirectional pedestrian tr a ffic measuring system using a pair of linear CCDs for accurate, real-time measurement at a heavy pedestrian traffic site. The system monitors the radiance at two parallel lines on the floor from above, and measures the number and the direction of pedestrians crossing the lines by computing the change in radiance patterns. The system consists of an image pickup unit (including optical system, CCDs and the driver), a data transfer unit, and an information processing unit (personal computer). The data transfer unit has two ports of buffer memories and transfers data from the image pickup unit to the information processing unit at high speed (approximately one frame of data per millisecond) in the asynchronous transmission mode. The information processing unit computes the number and the direction of the pedestrians from the two-valued radiance pattern data obtained by the CCDs. The pedestrian measurement algorithm has been designed so as to cope with the cases where more than one pedestrian crosses at the same time either side by side or one after another without a space between them. The experimental system with an optical system of F2.0, a CCD storage time of 20.0 ms, and an illuminance of 32.2 lx on the CCD photoreceptor surface, has made accurate measurements of pedestrians even when they crossed in opposite directions or side by side at the same time.
The CIE Standard Illuminant D65, used for specifying non-luminous object colors as a representative of average daylight, is defined by the relative spectral power distribution and no standard source for realizing the illuminant has been recommended. A fluorescent lamp simulating the illuminant D65 was designed by optimizing the metamerism indices (MI's) and the color rendering indices (CRI's) with a combination of three kinds of phosphors. The lamp was developed by coating the phosphor mixture as only a single layer on its inner surface. As initial characteristics, the visible range and the ultraviolet range MI's are in the class BC, the general CRI is about 98, and the special CRI's Ri (i=9.15) are larger than 90. The lamp characteristics during the lifetime were examined. The lumen maintenance after 1000 hours burning is about 93 per cent. The MI's can be kept in the BC class and the general and the special CRI's during the period are more than 95 and 85, respectively. The lamp characteristics during the lifetime were examined. The lumen maintenance after 1000 hours burning is about 93 per cent. The MI's can be kept in the BC class and the general and the special CRI's during the period are more than 95 and 85, respectively. The fluorescent lamp D65 simulator has better characteristics and is more practical than the JIS Xenon Standard White Source, officially recommended in Japan for the color matching practice.
It seems that there are no problem on the lamps for general lighting. But if we make carefully an investigation about it in detail, there are various probrems related to practical properties. The outline will be described as follows.(1) incandescent lamp: low luminous efficacy, short life.(2) fluorescent lamp: inconvenience by its long size.(3) fluorescent-mercury lamp: lumen maintenance.(4) self-ballasted mercury lamp: low luminous efficacy.(5) high pressure sodium lamp: expensive in usage and no device for safty system.(6) metal halide lamp: poor reliability of starting, lumen maintenance, flicker, etc. In this paper I chiefly describe an experimental study of these main problems. Though this research is still continuing, the auther has reached a certain conclusion. The auther provides here an outline of my findings and hopping that you will kindly provide me your comments.
Recently, bactericidal radiation (253.7nm) has been widely used to not only sterilizing but also semiconductor, food industries and so on. However, the ways of calibration for the radiation sources and/or the radiometers have not been established for the bactericidal irradiance. The bactericidal irradiance could be measured by the two ways of spectroradiometry and combining the thermal detector with optical filters. In our measurement, the difference between the values obtained by the two ways was few percents and so it was confirmed that both ways were useful. On use of the thermal detector, the calibration were carried out by following standards and methods: (1) using a total (whole wavelength) irradiance standard, (2) using a luminous intensity standard with broad band-pass filter and (3) using a spectral irradiance standard with broad band-pass filter. The calibrated values of these standards were probably same within 2.5%, it was confirmed that each standard was useful for calibrating the thermal detector. Irradiance of GL-15, which is a typical bactericidal lamp, was measured in the wavelength region of 250-2500nm. As the results, the rate of the bactericidal (253.7nm), another ultra-violet and visible and infrared radiation to total one were about 80%, 8 % and 12% respectively. Most of the infrared radiation was emitted nearby electrodes.