LED is regarded as the latest and the fourth generation of light sources following incandescent lamps as the first generation, fluorescent lamps as the second generation, and HID lamps as the third generation. Excellent characteristics, such as high efficiency, long life, compactness, light weight, mercury free, very weak IR and UV emission, etc. are their advantage in comparison with the conventional light sources. With the progress of LED lighting technologies, their application is spreading in sign and display device, spot lighting, base lighting, security lighting, and further, new market, which is impossible to realize by the conventional light sources, is expected. This article reports the latest trend in LED lighting.

View full abstract

As a demonstration, this system has been introduced into actual offices in Tokyo. These systems consist of fluorescent lighting fixtures, light control units, microprocessors, illuminance sensors and distributed optimization software. The lower control limit of a fluorescent light fixture is between 20% and 30%. We measured the relationships between color temperature and a dimming range of illuminance. The experimental results showed the dimming range of illuminance was narrow. To provide each worker's desired illuminannce and color temperature, the LED ceiling light, which can control the luminance between 0% and 100%, is desired. However, the LED ceiling light for the office use has not been developed so far.
The two leading lighting equipment makers prototyped the LED ceiling lights. We developed the intelligent lighting system using these lights, and verified its effectiveness. The experimental results showed the proposed system could provide required illuminance and color temperature, could make energy saving of 60-80%. The intelligent system has high affinity with a LED light. From the point of view of effective utilization of energy, the intelligent lighting system using the LED ceiling lights showed a good performance.

View full abstract

We investigated the photoluminescence (PL) property of ZnAl₂O₄:Mn powder phosphors prepared by a solid phase method. The mixture of ZnO, α-Al₂O₃ and MnCl₂ powders as sources were firing in the air at 1200 °C, followed by the thermal treatment in the reducing atmosphere at temperatures (T_r) from 800 to 1200 °C. The samples exhibited a highly chromatic pure green PL by exciting the ground state to the ⁴T₂(⁴G) level in the Mn²⁺ luminescent center with a 450 nm light. The PL spectra, consisting of a narrow emission band with its peak at 511 nm, depended strongly on the synthesis conditions. The reducing treatment dramatically increased the PL intensity although the as-synthesized samples showed very week PL. The full width at half maximum of the emission band remained small with a value of about 21 nm for T_r up to 1000 °C although it tended to broaden for higher T_r, which was correlated well with the change in the PL excitation spectra. The PL properties are discussed in conjunction with the crystallographic property characterized by x-ray diffraction in terms of the use as a color converter in white-light-emitting diodes for backlight units.

View full abstract

The purpose of this paper is to show application of light sources to medical field. It is described the process of light sources development applied to photodynamic therapy; PDT or photodynamic diagnosis; PDD. Actually, as a successful experience, we show the verification results obtained by primary and clinical experiments using metal halide lamp which emitted spectra is optimized to absorbed wavelength of photosensitizer for PDT.

View full abstract

An excimer lamp constructed by a piezoelectric transformer (PT) has been developed and studied in our laboratory. The excimer lamp is based on the excitation of dielectric barrier discharge (DBD) generated by the PT surface that induces high-voltage due to the piezoelectric effect. Spectroscopic measurement in the vacuum ultraviolet (VUV) region is performed for the excimer lamp filling with a He-Xe mixture and Ar. Emission spectra having a peak at 172 and 126 nm are found, which are respectively radiated from the Xe₂^* and Ar₂^* excimers that returns to ground states. A self-organization phenomenon (SOP) is also recognized in the He and Ar DBD. Static and time-resolved observations of the self-organized patterns are performed by a single reflex and ICCD cameras, respectively. The formation of self-organized patterns in argon requires a small amount of the air as an additive. From the time-resolved observation, we found dark spots arrayed hexagonally in a weak emission on the PT surface whose arrangement well coincides with that of bright hexagonal filaments. The dark spots are considered as the traces of the accumulated charges on the dielectric electrode, which interrupt the hexagonally filamentary discharges.

View full abstract

A microwave excited gas discharge lamp using a novel configuration of a coaxial line has been developed for application to VUV light source. The microwave propagated through the coaxial line consisted of the excited microwave plasma itself as the inner conductor and a metal tube as the outer conductor. The microwave power was launched directly from the antenna of the magnetron power source to the quartz discharge tube without using any impedance matching network. The length of the plasma was logarithmically increased with increasing the microwave power. A 2m-long uniform microwave plasma was obtained by using a couple of magnetron power sources on both the sides operated by alternating half-rectified sinusoidal wave high voltage source.

View full abstract

A compact metal halide lamps have showed high luminous efficacy and long lamp life time, when they are ignited by an antenna-excited microwave discharge (hereafter abbreviated by AEMD). The impedance of the lamp in the steady state ignition has been derived to discuss properties and structures of the lamp, using the equivalent electric circuits for the microwave circuit and the lamp. The expressions for the resistance and reactance of the lamp impedance are applied to deduce the matching and resonance conditions to efficiently feed the microwave power into the lamp. It is found that these expressions not only explain measured lamp properties but also contribute to design the HID lamp structures.

View full abstract

In order to clarify the influence of nitrogen addition on the fundamental properties of plasma display panel (PDP) discharges in Ne/Xe(10%) gas mixture, the PDP discharges in Ne/Xe/N₂ gas mixtures have been simulated using an one-dimensional fluid model, based on the continuity equations for electrons, ions, excited atoms and molecules, the Poisson equation and the electron energy balance equation. From simulation results, it is found that pulsed discharge with a short time (∼100 ns) occurs once during every half cycle. In case of nitrogen concentration more than 100 ppm, the phase-delay of the gap-voltage and discharge current in Ne/Xe gas mixture PDP discharges began to appear.

View full abstract

In Kagoshima National College of Technology, based on investigation with “the job boost measure investigation work in a power supply area” undertaken in the 2005 fiscal year, we accepted the trust from Kyushu Bureau of Economy, Trade and Industry, and undertook “the small-and-medium-sized-enterprises personnel educating work which utilized the technical college etc.” for three years from the 2006 fiscal year to the 2008 fiscal year. As the trial of engineer educating according to the electrical engineering concept to the manufacturing field based on a conventional result, we act as a professor of the base technique for applying alternative energy (a fuel cell and a solar cell) in which social needs are powerful these days, and aim at aiming at cultivation of the problem-solving type engineer who can contribute to a low carbon society through manufacturing, we undertook this work according to the manufacturing bearer educating work (personnel educating and secured work of the manufacturing field) in the 2009 fiscal year of National Federation of Small Business Associations.

View full abstract

This paper presents a complex E&S modeling, which is developed with a complex approximation for the conventional E&S modeling. The complex E&S modeling is applied to analyze a permanent magnet motor and validity of the complex E&S modeling is demonstrated. The computation time of the complex E&S modeling can be considerably reduced in comparison with that of the conventional E&S modeling.

View full abstract

When an ac-exited coil faces a non-magnetic moving metal foil, an eddy current is induced in the conductor and the coil impedance is influenced by speed and thickness. By examining this speed and thickness characteristics, a coil is used as the thickness sensor.
In this paper, we derive rigid theoretical formulas for magnetic field and coil impedance of a circle coil facing a standstill or movement foil conductor. And we present several characteristics with regard to coil inductance and resistance by calculations. The good agreement between the theoretical value and measured value demonstrates the validity of the method. We found that there is not an influence with speed at tens of micrometers thickness, and that the exciting frequency upper limit is 1 kHz.

View full abstract

The International Electrotechnical Commission (IEC) has prescribed an immunity test (IEC61000-4-2) of electronic equipment against electrostatic discharges (ESDs), in which a discharge current to be injected onto equipment under test is specified. As for the waveform, however, not the whole waveform but only the rise time, the first peak, and the current amplitudes at 30 ns and 60 ns are given in the time domain together with their uncertainties, which are required to check on the condition that an ESD generator (ESD-gun) shall be arranged vertically to an IEC recommended calibration target and its earth return wire is kept away as far as possible from a vertical ground plane (IEC standard arrangement). In this study, to clarify how arrangements of an ESD-gun and its earth return wire affect discharge currents, we measured discharge current waveforms for contact discharges of an ESD-gun onto an IEC calibration target with respect to various inclinations of the ESD-gun and arrangements of its earth return wire, and also calculated their current power spectra normalized to that of the discharge current for the IEC standard arrangement. As a result, we found that inclinations of the ESD gun affect the first peak current, which increases current power spectra by 14 dB at frequencies over 300 MHz, and that arrangements of the return wire influence the current waveforms between the first and second peaks, which provides variations in power spectra by ±12 dB in the frequency range from 10 MHz to 200 MHz. This finding suggests that arrangements of an ESD gun and its earth return wire are likely to cause different immunity test results. It was also found that in comparison with measured discharge currents for the standard arrangement, the calculated waveform of a discharge current from a formula, which has been included in the recent standard, has a more gentle falling waveform, and produces power spectra of +15dB in the frequency range from 10 MHz to 200 MHz and -12 dB at frequencies over 300 MHz.

View full abstract

It is well known that magnetic properties deteriorate in constructed cores due to conditions stressed by riveting and welding during manufacturing process, punching and sharing in cutting process of the electrical steel sheets and so on. Therefore, it is important to know the relationships between the stress and magnetic property of the electrical steel in order to design the electrical machinery. In this paper, the local residual stress distribution on the cross section of the stator core in a rotating machine is measured with a X-ray stress measurement device. As the result, the difference of the residual stress distribution of each component is obtained in the teeth and core back of the stator core. In addition, we estimated the deterioration of the magnetic property in the teeth region. It was clarified that the magnetic properties of the electrical steel sheet is deteriorated due to the residual stress.

View full abstract

Poly-lactic acid (PLA), a biodegradable plastic, has excellent electrical insulation properties at temperatures ranging from room temperature to around 70°C. At temperatures higher than 70°C, however, the insulation performance of PLA deteriorates due to its poor heat resistance. In this study, PLA was heat-treated at 100°C to endow it with greater heat resistance, and the effects that this heat treatment had on the electrical properties of PLA were investigated. Before being subjected to heat treatment, crystallinity (x_c) of PLA was about 6%. After the heat treatment was begun, x_c increased in proportion to the heat treatment time, such that measurements revealed that x_c had increased to about 42% by the time 15 minutes had passed since the start of the heat treatment. The temperature dependence of the insulation breakdown strength (E_B) of heat-treated PLA was investigated, and it was found that E_B of heat-treated PLA (PLA-A) decreases at a more moderate rate at temperatures higher than 60°C.

View full abstract

In this study, we investigated a water treatment method spraying the droplets of wastewater into pulse discharge space. The water treatment was carried out by applying voltage with different pulse widths to determine the optimum pulse width, and the optimum pulse voltage determined on the basis of the results of the study was analyzed. The rise time of the voltages with pulse widths of 40, 60, and 80 ns was about 12, 19, and 32 ns, respectively, and the discharge current in the case of the faster rise time was higher. The number of streamer discharges is believed to increase with a decrease in the rise time. The energy efficiency in the case of the pulse width of 40 ns is higher than that in the case of the other pulse widths. This is because almost all of active species are generated by early streamer discharge, and longer discharging time by longer pulse width makes more ineffectual energy by thermal loss. These results show that the pulsed voltage of faster rise time and shorter pulse width is optimum for the treatment.

View full abstract

This paper describes the development and the questionnaire survey of the simple electrolysis kit “Eneppa”. The junior high school student was able to conduct the experiment on electrolysis with this experiment kit at home. The teaching practice was done for the junior high school student with a developed experiment kit, and the questionnaire was analyzed. As a result, the student used this kit as a familiar experiment teaching material, and was practicing the content of study at the school with the family and the friend.

View full abstract

In this research, crack formations and developments in ice on ice breaking by pulsed power were investigated using high-speed camera. The pulsed arc discharge was created in water using Marx generator. Shock wave was produced and propagated in water, and then the ice surface was loaded by pressure of shock wave. Cracks were formed inside ice body, and were developed. A velocity of crack development of 2900 m/s was obtained at a discharge peak power of 160 MW from images of high-speed camera. It was found that the velocity of crack development was increased with increase of discharge peak power.

View full abstract

The atmospheric pressure nonthermal plasma-graft polymerization treatment is applied for the surface modification of the organic fibers in order to enhance the strength of the aerospace structural composite material consisting of the laminated textiles. The influence of the treatment on the composite materials' strength properties is examined. As a result, the plasma-graft polymerization surface treatment is effective for the compression and bend of the composite materials. Because the interfacial bonding between each fiber and matrix resin is strengthened by the treatment, the strengths of the composite materials are increased.

View full abstract