Electric lamp and discharge devices: systems – Combined load device or load device temperature modifying... – Discharge device load
Reexamination Certificate
2001-05-25
2003-08-19
Wong, Don (Department: 2821)
Electric lamp and discharge devices: systems
Combined load device or load device temperature modifying...
Discharge device load
C315S058000, C315S082000, C315S248000, C315S246000, C313S620000, C313S623000, C313S625000
Reexamination Certificate
active
06608444
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a mercury-free high-intensity discharge lamp operating apparatus and a mercury-free metal halide lamp that do not contain mercury as the luminous material.
In recent years, high-intensity discharge lamps for general lighting, projectors and vehicle headlights are being used. High-intensity discharge lamps have advantages of high efficiency, low power consumption, and brightness, compared with halogen lamps, so that the high-intensity discharge lamps are expected to be widely used. One of the high-intensity discharge lamps that are expected to be widely used is a metal halide lamp.
FIG. 1
shows a cross sectional configuration of a metal halide lamp.
The metal halide lamp shown in
FIG. 1
includes an arc tube (luminous bulb)
1
made of quartz glass and sealing portions
2
that are positioned at both ends of the arc tube
1
and seal the arc tube
1
. A pair of electrodes
3
made of tungsten are provided in the arc tube
1
, and a luminous material
6
including mercury and metal halide, and a rare gas (not shown) are enclosed in the arc tube
1
. The pair of electrodes
3
in the arc tube
1
are connected to molybdenum foils
4
at one end, and the molybdenum foils
4
are sealed with the sealing portions
2
. Lead wires
5
are connected to the other ends of the molybdenum foils
4
. The lead wires
5
are to be electrically connected to a ballast (not shown).
The principle of light emission of the metal halide lamp shown in
FIG. 1
will be described briefly. When the lamp is turned on by applying a voltage to the lead wires
5
from the ballast, a part of or the entire metal halide
6
evaporates. Then, the evaporated metal halide is dissociated to metal atoms and halogen atoms by arc discharge occurring between the pair of electrodes
3
, and thus the metal atoms are excited so that light is emitted. In the vicinity of the wall of the arc tube
1
, the dissociated metal atoms are recombined with the halogen atoms, and return to a metal halide. This cycle phenomenon is repeated to allow the lamp to be stably on. In general, although the metal halide has a lower vapor pressure than that of mercury, the metal halide is readily excited and emitted, so that there is a tendency that emission caused by an added metal mercury is stronger than emission caused by mercury in metal halide lamps. Therefore, mercury primarily serves as a buffering gas to determine a voltage in the arc tube
1
. A rare gas in the arc tube
1
serves as a gas for starting the lamp.
In general high-intensity discharge lamps including the metal halide lamp shown in
FIG. 1
, the lamp is operated while the straight line connecting the pair of electrodes
3
is horizontal (hereinafter, referred to as “horizontal operation”), an arc
7
occurring between the pair of electrodes is curved upward by convection current of the vapor in the arc tube
1
, as shown in FIG.
2
. When the degree of curving is large and the arc
7
is attached to the wall of the arc tube
1
, the temperature to the upper portion la of the arc tube
1
is locally high, so that devitrification or deformations of the upper portion
1
a
of the arc tube start comparatively in an early stage. As a result, the lifetime characteristics of the lamp are degraded.
In order to suppress the curving of the arc
7
to improve the lifetime characteristics of the lamp, there are several proposals. One of them is a technique of applying a magnetic field to a metal halide lamp to suppress the curving of the arc, which is disclosed, for example, in Japanese Laid-Open Patent Publication Nos. 55-86062 and 9-161725. The technique disclosed in Japanese Laid-open Patent Publication No. 55-86062 includes the step of disposing a strong rare earth magnet above the arc tube
1
in a metal halide lamp containing mercury in the arc tube
1
to lower the arc
7
down by utilizing repulsion (Lorentz force) between the magnet and the arc 7, thereby suppressing the curving of the arc
7
. On the other hand, the technique disclosed in Japanese Laid-open Patent Publication No. 9-161725 uses an electromagnet as means for applying a magnetic field, in place of the rare earth magnet. There are other disclosures of the technique of utilizing an electromagnetic to change the position of the arc, such as Japanese Laid-Open Patent Publication No. 11-312495, 11-317103, and 2000-12251.
Nowadays, environment is an important issue, and metal halide lamps not containing mercury are desirable in view of environmental issues arising when disposing of waste. Therefore, the inventors of the present invention compared and examined mercury-free metal halide lamps and metal halide lamps containing mercury to develop mercury-free metal halide lamps.
As a result of the examination, the mercury-free metal halide lamps have significantly different characteristics than those of metal halide lamps containing mercury. For example, in a mercury-free metal halide lamp, arc curving can be suppressed by applying a magnetic field to the mercury-metal halide lamp. However, the manner in which a magnetic field is applied and the principle of suppression of curving are very different from those for the metal halide lamp containing mercury. Furthermore, depending on the intensity of the magnetic field, the arc
7
itself is unstable and a phenomenon that the arc
7
vibrates was observed. This vibration of the arc
7
is not preferable because it results in a flickering when used as a lamp.
SUMMARY OF THE INVENTION
Therefore, with the foregoing in mind, it is a main object of the present invention to provide a mercury-free high-intensity discharge lamp operating apparatus and a mercury-free metal halide lamp in which arc vibration is suppressed and flickering is prevented.
A mercury-free high-intensity discharge lamp operating apparatus of the present invention includes a horizontally operated high-intensity discharge lamp including an arc tube in which a luminous material is enclosed and a pair of electrodes are arranged in the arc tube; a ballast including an alternating current generation means for supplying alternating current to the pair of electrodes; and a magnetic field application means for applying in substantially vertical direction a magnetic field having a component that is substantially perpendicular to a straight line connecting heads of the pair of electrodes; wherein mercury is not included as the luminous material in the arc tube; and the present invention satisfies the relationship
0<(100
BW/f
)−
P
0
d<
100
wherein B(mT) is the magnetic field applied to a center between the heads of the pair of electrodes, d(mm) is a distance between the heads of the pair of electrodes, P
0
(MPa) is a pressure inside the arc tube during steady-state operation, W(W) is a power consumed during steady-state operation, and f(Hz) is a steady-state frequency during steady-state operation.
A mercury-free high-intensity discharge lamp operating apparatus of the present invention includes a horizontally operated high-intensity discharge lamp including an arc tube in which a luminous material is enclosed and a pair of electrodes are arranged in the arc tube; a ballast including an alternating current generation means for supplying alternating current to the pair of electrodes; and a magnetic field application means for applying in substantially vertical direction a magnetic field having a component that is substantially perpendicular to a straight line connecting the heads of said pair of electrodes; wherein mercury is not included as the luminous material in the arc tube, and at least a rare gas is included in the arc tube; and the present invention satisfies the relationship
0<(10
BW/f
)−
Pd<
10
wherein B(mT) is the magnetic field applied to a center between the heads of the pair of electrodes, d(mm) is a distance between the heads of the pair of electrodes, P(MPa) is a pressure of the enclosed rare gas at 20° C., W(W) is a power consumed during steady-state operation, and f(Hz) is a steady-state frequency during steady-s
Kaneko Yuriko
Kiryu Hideaki
Minamihata Ryo
Murase Takayuki
Takahashi Kiyoshi
Harness & Dickey & Pierce P.L.C.
Vo Tuyet T.
Wong Don
LandOfFree
Mercury-free high-intensity discharge lamp operating... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Mercury-free high-intensity discharge lamp operating..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Mercury-free high-intensity discharge lamp operating... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3120579