|An Electronic Ballast for Electrodeless Fluorescent
Futoshi OKAMOTO, Hiroki HASEGAWA, Kazurou HARADA, Yoshiyuki ISHIHARA,
And Toshiyuki TODAKA
We experimentally investigated an electronic ballast for electrodeless
fluorescent lamps operated at 150,200, and 400 kHz in order to achieve
high efficiency, low cost and low EMI. An efficiency of around 96%
was obtained, and the EMI at 200 kHz was lower than that at 2.65
MHz. The EMI from lamps with the coil inside was lower than from
those with the coil outside at the same driving frequency.
KEYWORD?Felectrodeless fluorescent lamp, electronic ballast, halfbridge
inverter, radiated noise
|An Electronic Ballast Combined with an HF Inverter and Boost
Futoshi OKAMOTO, Hiroshi KIDO, Akinori HIRAMATU and Toshirou
A ballast circuit with an inverter combined with a chopper is
a circuit in which the inverter and chopper share at least one
switching element. We have developed a ballast circuit with a
newly designed dimming control circuit and drive circuit. Dimming
control (Complementary PWM control) is achieved by making the
continuity time of one switching element (Q1) longer, while making
the continuity time of the other switching element (Q2)shorter,
and vice versa. The drive circuit (self-excited and externally-excited
multi-drive circuit with switching element Q1) is self-excited
by the feedback of the oscillating current from the resonance
circuit. while switching element Q2 is excited by the external
signal. This circuit can run a pair of fluorescent lamps (FLR40S/M).
An input power factor of 98% or more, a THD of 13%" or less,
and no substantial variation in the smoothed DC voltage were obtained
under three conditions : full power (100% light output ratio),
dimming level 1 (80% light output ratio), and dimming level 2
(55% light output ratio).
KEYWORD?Felectronic ballast, dimmer, inverter, chopper
|A Novel Cold Cathode Fluorescent Lamp with an
Kiyoshi NISHIMURA, Jun YAJIMA and Kunio YUASA
A novel cold cathode fluorescent lamp (CCFL) with an adiabatic
layer suitable for backlighting of PDAs (Personal Digital Assistants)
is described. The adiabatic layer (100-200ƒÊm) is formed between
a light tube and an outer tube and is filled with low-pressure
gases. This raises the temperature of the light tube to the suitable
value (50-70), which maximizes efficiency even in low lamp wattage
operation and in low ambient temperature. The results of experiments
and heat transfer analyses show that the optimum pressure in an
adiabatic layer lies between 1 Pa and 10 Pa. At a pressure of
less than 1 Pa, the lamp maintains the temperature at a constant
level because of the conduction loss is lower than the radiation
KEYWORD:cold cathode, fluorescent lamp, heat transfer,
|Effects of Auditory Tasks on Functional Visual Field against
Miyoshi AYAMA, Maki MATSUZAWA, Yoshito MEKADA and Masao KASUGA
The functional visual field (FVF) of target localization against
a dynamic background simulating highway driving was precisely
measured under four different auditory task conditions to investigate
whether conversing on a mobile phone affects a driver's . The
FVF is the visual field in which a person can achieve some kind
of visual task, such as target detection or localization. The
task conditions were no auditory information, listening to BGM,
listening to a simple conversation and understanding it, and listening
to a simple question and answering it orally. Individual differences
were found in the size of the FVF and the effect of the tasks.
The FVF area of the largest subject was twice that of the smallest
subject under the same condition. Shrinkage of the FVF was found
under the oral answer condition for the two subjects who had never
used a mobile phone while driving, while no significant change
under any condition was found for the subject who made a long
drive every day and was used to talking on a mobile phone while
driving. This suggests that conversation can reduce a drivers'
attention and shrink the FVF of some drivers.
KEYWORD:Ffunctional visual field, target detection,
target localization, driver's visual ability, mobile
|Impedance of Electrodeless RF Spherical Light Source with Plasma
Motoichi KAWAGUCHI and Makoto TOHO
One method for determining the impedance of an inductively coupled
low-pressure argon plasma tube is described. Designed for application
to inductively coupled fluorescent light sources, it was a spherical
discharge tube and an induction coil wound on its equatorial surface.
The pressure of the argon gas is around 100 Pa, and the frequency
of the rf coil current is around 10 MHz. By assuming uniformity
of the plasma density and electron temperature, an analytic solution
for the electromagnetic field is easily obtained. Using this solution,
we can obtain a convenient approximate calculation of the spatial
distribution of the electric current and plasma impedance. The
results of numerical calculation of impedance are given and compared
with experimental results.
KEYWORD:inductively coupled discharge, low-pressure
argon light source, calculation of impedance
|Feasibility of Two-Photon Emission Phosphor with Atomic Activator
Makoto TOHO and Hideyoshi KIMURA
Lighting products consume about 20% of total electric power,
so the lighting industry should take a large responsibility for
energy saving. Fluorescent lamps are a particularly critical light
source for energy saving because they are widely used. Although
the fluorescent lamp has high efficiency. its energy-transition
rate is still as low as 25%. There is thus much room for improvement.
The key issue for efficiency improvement is the phosphor technology.
Phosphors have been researched and improved based on the one?õ?photon
emission theory. Currently, the highest phosphor efficiency (transition
rate of UV to visible) is over 40%. However, the energy of 254nm
UV photon of Hg discharge is 4.9eV, which could be transferred
to two visible photons.
We investigated the feasibility of the two-photon approach. We
specifically studied a phosphor with an activator of a metal atom
in an atomic state, which produces atomic-like emissions from
an isolated metal atom fixed in a matrix. First, we theoretically
studied the selection of possible metal atoms and analized the
probability of two-photon emission. We searched for a method for
fixing and isolating atoms in a matrix at room temperature and
analyzed the energy shift of an excited atoms. As a result, we
could have a prospect of the feasibility. Next, we conducted an
experiment to fabricate a new phosphor sample by fixing an atom
in an atomic state in a matrix and evaluated the performance of
the samples. We selected Fe atoms, an amorphous silica as a matrix,
and sol-gel fabrication method.
We found that Fe atoms on a silica matrix were fixed in an atomic
state by sol-gel fabrication and emitted fluorescent light at
lower atomic densities. However, the emission was not made by
the visible two-photon transition, but by continuous deep-blue
KEYWORD: phosphor, two-photon emission, atomic activator,
high efficiency, fluorescent lamps
|All Sky Model as a Standard Sky Luminance Distribution
-- Part 1. Measurement and Arrangement of Data and Parameters
for a Standard Sky --
Norio IGAWA, Hiroshi NAKAMURA, Tomoko MATSUZAWA and
Natural light should be effectively used for a low-energy-consuming
daylighting design. A useful sky luminance distribution
model is thus required for estimating and evaluating
a daylit environment as a standard sky. We previously
developed a standard sky model named the ALL SKY MODEL.
It can represent the sky luminance distribution from
clear sky to overcast sky continuously.
We have now modified the procedure for constructing
the model so that the index for estimating the sky luminance
distribution can be derived easily.
The standard global illuminance was defined based on
global illuminances of clear skies. The normalized global
illuminance was obtained by dividing the measured global
with the standard global illuminance, and was selected
as the index for estimating sky luminance distribution.
This paper describes the new construction procedure:
the gathering of raw data the arrangement of data and
the selection of indices for estimating the sky luminance
distribution. It also reviews various standard skies
proposed by researchers worldwide.
KEYWORD:sky luminance distribution, standard sky, daylighting
design, All Sky Model
|Economic Value of Light Pollution -- Evaluated Using
Contingent Valuation Method --
Rikuo MURAMATSU, Yoshiki NAKAMURA and Masahiko TAKANO
The economic value of light pollution was evaluated
using the contingent valuation method as the basis of
a survey by questionnaire of residents of urban areas.
Comparison of the evaluated value with the subjects'
environmental consciousness in general and their environmentally
friendly behaviors in daily life suggested valuable
methods for deeply understanding consciousness of light
KEYWORD:contingent valuation method, light pollution,
|Irradiance and Heating Power Distribution Characteristics within
a Substancewhen Water Containing Flat Material is Heated with Infrared
-- Theoretical Calculation and General Considerations
-- Mahito ICHIKAWA and Hisanori NAKAO
Short-, medium- and long-wave infrared emitters
have different effects on the temperature-rise and drying-rate
characteristics in infrared radiation heating of water
containing flat material. Accordingly they also significantly
affect thermal efficiency. The heating characteristics
also depend on the thickness of the heated material.
It is known that absorbed radiation flux changes to
heat within the heated substance, the absorption depends
to a large extent on the amount of water in the substance,
and the Lambert absorption coefficient of water varies
significantly between the three wave-length regions.
The coefficient is higher in the long-wave region, moderate
in the medium one, and much lower in the short one.
We assumed that the infrared emitter used was a black
or perfectly grey body and that the heated substance
acted as free water, and calculated the irradiance and
generated heating-power distributions within the substance.
The thickness in millimeters of the substance needed
to absorb about 90?“ of the incident radiation flux is
indicated by D's in the Figure and Table. The heating-power
generated at the irradiated surface when heated by a
long-wave emitter was noticeably higher. The high drying-rate,
which is characteristic of long-wave emitter heating,
is attributed to the concentrated heating-power at the
irradiated surface. This high heating-power provides
large latent heat for evaporation. The obtained results
of Figures and Tables give basic and useful Informations
for choice in advance of the emitter kind between the
three ones in infrared heating of a water contained
substance with a given thickness.
KEYWORD:infrared heating, infrared drying, long-wave
Study on Color Temperature Error Observed in the System of
Combined RGB Fluorescent Lamps
Shigeo GOTOH, Ichiro FUJITA and Motoi WADA
The color temperature of the light generated
by the illumination system of the combined RGB fluorescent
lamp system was shown to disagree with the estimated
value obtained from a simple model based on lighting
data for three single fluorescent lamps. The discrepancy
was not caused by the change in the light spectrum of
each lamp due to the input power control, but was caused
by the change in the luminous flux from the lamps. The
error in the luminous flux estimated for the given lamp
power was attributable to the spatial distribution of
the light emission from the lamp. The magnitude of this
error was typically 2 to 3%.
KEYWORD:fluorescent lamp, luminous flux, color, dimming