Electric lamp and discharge devices – With gas or vapor – Having baffle – partition – or constricting means affecting...
Reexamination Certificate
2001-09-25
2003-11-25
Patel, Nimeshkumar D. (Department: 2879)
Electric lamp and discharge devices
With gas or vapor
Having baffle, partition, or constricting means affecting...
C313S607000, C313S234000, C315S248000
Reexamination Certificate
active
06653783
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to electrodeless discharge lamps. In particular, the present invention relates to electrodeless discharge lamps in which a coil is provided inside a bulb.
Some discharge lamps are electrodeless discharge lamps that do not include electrodes. Since electrodeless discharge lamps do not include electrodes, they advantageously have a longer life than that of discharge lamps including electrodes that ends their life by depletion of an electron release material on the electrodes. The electrodeless discharge lamps emit light in an ultraviolet ray range or visible light range by the following operation. A high frequency alternating magnetic field, for example, from 50 kH to 50 MHz is generated by a coil, and luminous gases such as a rare gas, mercury, metal halide and the like enclosed in a bulb are excited by an induction field generated by the high frequency alternating magnetic field. The excitation of the luminous gas provides light emission in an ultraviolet ray range or a visible light range. Emitted light in an ultraviolet ray range can be converted to light in a visible light range by phosphors.
FIGS. 16A and 16B
are schematic views showing the configuration of a conventional electrodeless discharge lamp.
FIG. 16A
is a cross-sectional view including the central axis of a core
1106
, and
FIG. 16B
is a cross-sectional view taken along a line X-X′.
Referring to
FIGS. 16A and 16B
, the configuration and the operation of the conventional electrodeless discharge lamp will be described. This conventional electrodeless discharge lamp is a lamp whose light is started and maintained by a high frequency alternating magnetic field generated in the vicinity of a coil, and is a (compact) self-ballasted electrodeless discharge lamp to which a lamp base
1101
is integrated.
The electrodeless discharge lamp shown in
FIGS. 16A and 16B
includes a lamp base
1101
, a power source (not shown) disposed inside a power source portion
1102
, and a translucent bulb
1104
in which a cavity
1105
is provided. A coil in which a winding
1103
winds around a cylindrical core
1106
is inserted in the cavity
1105
. The lamp base
1101
and the power source in the power source portion
1102
are electrically connected to each other, and the power source and the winding
1103
are also electrically connected to each other. In
FIG. 16A
, for clarification of the drawing, the vicinity of the central axis of the core
1106
and the lines of magnetic force (dotted lines) are shown in cross section, and the lamp base
1101
, the power source portion
1102
, the bulb
1104
are shown in their outlook.
When a commercial alternating current power is supplied to the power source (not shown) in the power source portion
1102
via the lamp base
1101
, the power source portion
1102
converts the commercial alternating current power to a high frequency alternating current power, and supplies it to the winding
1103
. The winding
1103
that has been supplied with the high frequency alternating current power forms a high frequency alternating magnetic field as shown by lines of magnetic force &ogr; in a space near the coil. When a high frequency alternating magnetic field is formed, an induction field orthogonal to the high frequency alternating magnetic field is generated, and then luminous gases in the bulb
1104
are excited and light is emitted. As a result, light in an ultraviolet ray range or a visible light range can be obtained.
However, the configuration of the conventional electrodeless discharge lamp shown in
FIGS. 16A and 16B
has the following problems. In the conventional configuration, the high frequency alternating magnetic field radiated from the coil as shown in the lines of magnetic force &ogr; leaks out from the bulb
1104
, so that the magnetic field inside the bulb
1104
is reduced. As a result, the induction field formed by the magnetic field is reduced, which makes it difficult to start the lamp. In particular, when the ambient temperature is low, the startability of the lamp is significantly poor.
SUMMARY OF THE INVENTION
Therefore, with the foregoing in mind, it is an object of the present invention to provide an electrodeless discharge lamp with improved startability.
An electrodeless discharge lamp of the present invention includes a translucent bulb enclosing a luminous material; a coil for generating an alternating magnetic field that causes discharge in the luminous material; a power source for supplying an alternating current to the coil, the coil including a core and a winding provided near the bulb; and further includes startability improving means for improving startability of the lamp by generating a portion in which the alternating magnetic field generated by the coil is intensified in the bulb.
In one preferred embodiment, the coil is inserted in a cavity provided in the bulb.
In one preferred embodiment, the electrodeless discharge lamp further includes a phosphor applied onto the inner surface of the bulb.
In one preferred embodiment, the luminous material includes mercury and a rare gas.
In one preferred embodiment, the startability improving means is constituted by providing a high permeability member including a soft magnetic material near the core.
In one preferred embodiment, the high permeability member is provided in the bulb.
In one preferred embodiment, the high permeability member is a magnetic thin film provided on a surface of the bulb.
In one preferred embodiment, the high permeability member is plate-shaped and is inserted between the power source and the bulb.
In one preferred embodiment, the plate-shaped high permeability member has an asymmetric shape in which it is not symmetric with respect to the central axis of the core.
In one preferred embodiment, the plate-shaped high permeability member has a circular plate-like shape.
In one preferred embodiment, the center of the circle of the circular plate-shaped high permeability member is positioned in a portion other than the central axis of the core.
In one preferred embodiment, the high permeability member has such a U-shaped cross-section that the high permeability member surrounds the bottom of the bulb positioned on the side of the power source and a part of the side face adjacent to the bottom.
In one preferred embodiment, the high permeability member has at least one protrusion, recess or notch.
In one preferred embodiment, the startability improving means is constituted by the coil in which the winding density of the winding wound around the core is sparse on the side of the power source and is dense on the side opposite to the power source.
In one preferred embodiment, the startability improving means is constituted by the coil in which cross-section areas of the core are different along the central axis of the core.
In one preferred embodiment, the startability improving means is constituted by the coil provided with the core made of two or more magnetic materials having different magnetic permeabilities.
In one preferred embodiment, the electrodeless discharge lamp of the present invention is constituted as a self-ballasted electrodeless discharge lamp further including a lamp base electrically connected to the power source.
According to another aspect of the present invention, another electrodeless discharge lamp of the present invention includes a bulb made of a translucent material and filled with a luminous material inside the bulb; a coil including a core and a winding disposed near the bulb; and a power source for supplying a high frequency alternating current power to the winding. The electrodeless discharge lamp has a configuration in which discharge inside the bulb is caused by a high frequency alternating magnetic field formed by the coil, and the high frequency alternating magnetic field inside the bulb is distributed non-uniformly at the cross-section orthogonal to the central axis of the core.
According to another aspect of the present invention, yet another electrodeless discharge lamp includes a bulb made of a
Hashimotodani Kiyoshi
Kawasaki Mitsuharu
Kurachi Toshiaki
Miyazaki Koji
Harness & Dickey & Pierce P.L.C.
Patel Nimeshkumar D.
Roy Sikha
LandOfFree
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