This paper explores the characteristic of the fluorescent lamp operating in high-frequency range. The fluorescent lamp actually characterizes an impedance consisting of resistance and capacitance, which is seriously dependent on the lamp current, operating frequency, and lamp voltage. A novel soft-starting strategy for pre-heating and igniting the fluorescent lamp is proposed. A half-bridge series-resonant inverter (HB-SRI) is employed as the electronic ballast to verify the system performance. A soft-starting controller (SSC) is implemented to realize zero-voltage switching for the power switches and lower igniting voltage for the lamp. Mathematical model for the lamp before and after firing is built. A design example realized by the HB-SRI is conducted, and the experimental result and the simulation one are close to the theoretical predictions.

Measuring the Ne-Hg negative glow lamp (having no positive column), authors found the efficiency decreased as frequency increased. Authors measured the characteristics of this plasma to grasp the reason for it. There are two groups of electrons in this plasma. One group consists of first electrons whose peak energy at high frequency (HF) operation is higher than at low frequency (LF). The other consists of second electrons whose energy at HF operation is lower than at LF. There was the period without first electrons at HF operation. From these results, authors attribute the reason for the decreasing efficiency to the followings. (1) The period of the energy transfer from first electrons to second electron at HF operation is shorter than at LF, because there is the period without first electrons at HF operation. (2) Ionization loss at HF operation is higher than at LF, because of the higher peak energy of first electrons. Lastly authors checked the negative glow performance of 2 lamps, which were Ne-Hg lamp and Ar-Hg lamp with positive column, to compare with that of Ne-Hg lamp without positive column, and confirmed that there are no difference among the negative glow performance of these 3 lamps. It is considered from these measurement that the peak of cathode fall voltage at HF operation is higher than at LF, in spite of the cathode fall voltage is lower at HF in r.m.s.

KEYWORDS: negative glow, plasma characteristics, frequency, cathode fall voltage, spectrum

The improvement of image quality has a close relation with lighting and lens in an automatic inspection system. The quality of image could affect the cost, speed and stability of an inspection system. The influences of the lighting configuration and the spherical aberration of lens in an automatic inspection system are studied by means of Monte Carlo (MC) method in this paper. The theoretical analysis and simulation results reveal as follows: when the light source deviates from the center of the inspection system, the planar light source with a large (small) inclination has a better illumination in the near (far) distance within a narrow (broad) scope. The illumination scope becomes broader as the sloped light source deviates from the center of the inspection system. There exist some symmetric distortions in the margin of the pattern while the spherical aberration presents. This research not only supplies an available method for the analysis of lighting configuration but also points out a new way for analyzing the aberration of lens.

A residence is a place for various living activities, for which a variety of lighting conditions should be studied, including the general lighting illuminance, illuminance distribution, luminance, luminance distribution, color rendering properties, and color temperature, to achieve an appropriate atmosphere with suitable lighting. Selecting the two factors of illuminance and color temperature, their effect on the atmosphere was scientifically studied. The experimental study of subjective appraisal was carried out with the semantic differential method, using experimental equipment developed to simulate various combinations of illuminance and color temperature. Observers were asked to make their appraisals by first participating in an imaginary scene involving an enjoyable conversation with family and/or friends and next by imagining themselves in a relaxed state drinking coffee alone. The first scene applies to a state that we shall refer to as the communal state, and the second scene to the solitary state.Analysis was performed on the result of how the preference changed with the adjustments of illuminance and color temperature. For the communal state, atmosphere preference grew with the increase of illuminance within the range between 100 lx and 400 lx, and was saturated at higher illuminance levels. For the solitary state, preference was not as closely related to illuminance, and observers expressed a slightly greater dislike for higher illuminance levels in comparison with low illuminance. The first activity showed a preference for higher illuminance levels, and the second activity showed a preference for lower illuminance levels. The results above were compared with Kruithof's.

It is possible to improve the distribution of illuminance on a floor by controlling the direction of daylight incident on the floor from a side window which is called a holographic window in this paper. The idea of a thin phase hologram makes possible uniform distribution of illumination throughout the year.  The special hologram may be made by annealing technology on a computer simulation algorithm.

This investigation concerns the measurement method of the human visual MTF properties using a computer display. In this paper, simplified visual MTF measurement was discussed. This paper compares the simplified measurement with the more precise measurement which has been known as general measurement. The test pattern used in the simplified measurement was a grating which had horizontally varied spatial frequencies and vertically varied contrast values. The sensitivity obtained by the simplified measurement is extremely low and the curvature is tranquil compared with the results measured by the precise measurement. This result suggests the pattern must be improved because the lower contrast area is too narrow to obtain an accurate value on the pattern. Latter evidence suggests the subject observed several different spatial frequency gratings simultaneously in his one glance. Taking these into account, the improved pattern was developed. After the MTF properties measurement by the improved simplified MTF pattern, the original MTF properties (precise measurement MTF properties) were estimated.

In bad weather conditions, e.g. rainy, foggy, and snowy conditions, exact slant visual ranges should be obtained for safe landings at airports. However, no equipment for achieving this has been installed in airports yet. In this study, the laser radar system is refined for estimating the slant visual range. It is found that the empirical data in bad weather conditions do not correspond to predictions with the current laser radar equation. Therefore, a new laser radar equation, which considers the divergence of the transmitting laser beam, is proposed. The slopes of this equation correspond well to the empirical data in various weather conditions. The visibilities estimated by this equation also correspond with those obtained by the slant transmittance system. Also, the extent of the divergence is examined by means of classifying the empirical data by weather conditions. As a result, it is found that the divergence of the transmitted laser beam increases in the order of rain, fog, misty rain, and snow.

KEYWORDS: [As translated in the Japanese text]