Electric lamp and discharge devices: systems – Combined load device or load device temperature modifying... – Discharge device load with distributed parameter-type...
Reexamination Certificate
2001-11-13
2003-09-09
Wong, Don (Department: 2821)
Electric lamp and discharge devices: systems
Combined load device or load device temperature modifying...
Discharge device load with distributed parameter-type...
C315S039770, C315S248000, C333S227000
Reexamination Certificate
active
06617793
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a lighting apparatus using microwave, and more particularly, to a resonator of a microwave lighting apparatus having a mesh structure which is capable of preventing microwave transmitted through a waveguide from leaking and transmitting light radiated from a light bulb outwardly, and its manufacturing method.
2. Description of the Background Art
A microwave lighting apparatus is an instrument to apply microwave to an electrodeless light bulb to obtain a visible ray or ultraviolet rays therefrom. The a lamp adopting microwave lighting apparatus has a long lifespan and an excellent illumination effect compared to the general electric lamp or a fluorescent lamp.
FIG. 1
is a vertical-sectional view of a general microwave lighting apparatus.
As shown in
FIG. 1
, the microwave lighting apparatus includes a magnetron
5
for generating microwave, a waveguide
3
for transmitting the microwave from the magnetron
1
, a light bulb
5
for generating light as a substance encapsulated in the light bulb is turned to plasma by the microwave energy transmitted thorugh the waveguide
3
, and a resonator
20
for covering the front side of the waveguide
3
and the light bulb
5
to prevent microwave from leaking and transmitting light radiated from the light bulb
5
.
With this fundamental structure, the microwave lighting apparatus further includes a high voltage generator
7
for boosting a common AC power to a high pressure and providing it to the magnetron
1
, a cooling unit
9
for cooling the magnetron
1
and the high voltage generator
7
, a reflection mirror
11
for collectively reflecting the light generated from the light bulb
5
forwardly, a light bulb motor
13
and a motor shaft
15
for rotating the light bulb
5
, and cooling the heat while discharging the light, and a controller (not shown) for controlling varous factors including the high voltage generator
7
and the cooling unit
9
.
In the microwave lighting apparatus, when the controller inputs a drive signal to the high voltage generator
7
, the high voltage generator
7
boosts a received AC power and provides the boosted high pressure to the magnetron
1
.
The magnetron
1
generates microwave having a very high frequency as being oscillated by the high pressure supplied from the high voltage generator
7
, and thusly generated microwave is radiated into the resonator
20
through the waveguide
3
to discharge the substance encapsulated in the light bulb
5
and generate light having an inherent discharging spectrum.
In this manner, the light generated from the light bulb
5
is reflected to the front side through the mirror
12
and the reflection mirror
11
and lights a place of its insulation site.
FIG. 2
is a perspective view of the resonator used for the microwave lighting apparatus in accordance with a conventional art, and
FIGS. 3A and 3B
are a detailed view of the portion ‘A’ of FIG.
2
and sectional view taken along line B—B of
FIG. 2
, respectively.
With reference to
FIG. 1
, the resonator
20
has a metal mesh form and is assembled at the side of exit
3
a
of the waveguide
3
, so that it impounds microwave transmitted through the waveguide
3
and transforms the microwave energy to light within the light bulb
5
, and at the same time, prevents the microwave from leaking and transmits the light generated from the light bulb
5
outwardly.
With reference to
FIGS. 2 and 3
, the resonator
20
includes, besides a portion of the opened portion
20
a,
a cylindrical unit
21
on which a plurality of holes
20
b
are formed by an etching process and a lid unit
25
formed convex and connected to the front portion of the cylindrical unit
21
, having a plurality of holes
20
b.
The cylindrical unit
21
includes a mesh portion
22
for preventing microwave from leaking and transmitting light, and a fixed portion
23
fixed at the outlet portion of the waveguide
3
. The fixed portion
23
is not subjected to the etching process. The fixed portion
23
included a plurality of slit portions
23
a,
so as is to be extended and easily assembled when it is installed at the waveguide
3
.
FIG. 4
is a flow chart of a process of manufacturing the resonator in accordance with the conventional art.
The process for manufacturing the resonator will now be explained with reference to
FIGS. 2 and 4
.
First, in order to fabricate the cylindrical unit
21
, a metal thin film of a predetermined thickness made of a stainless steel or phosphor bronze is cut in a rectangular shape, and the remaining portion except the fixed portion
23
is etched to form holes
20
b
to form a mesh portion
22
.
The holes
20
b
formed by etching the metal thin film has such a size as to prevent leakage of microwave and a maximum aperture efficiency so that the light radiated from the light bulb
5
of
FIG. 1
can be emitted outwardly at the maximum.
Next, the mesh thin film is bent to a cylindrical shape and the both end portions are put into contact and welded. At this time, the both end portions are put into contact and directly welded, or as shown in
FIG. 3A
, a reinforcing member
24
is applied on the portion where the both end portions
21
a
and
21
b
are put into contact and welded to fabricate the cylindrical unit
21
.
At this time, it is to be cautioned that the both end portions
21
a
and
21
b
of the mesh thin film shouldn't be welded as being folded. The reason for this is that, if a step is formed at the welded portion, when the resonator
20
is assembled to the waveguide
3
, a gap occurs between the resonator
20
and the waveguide
3
, through which microwave may be leaked.
In order to fabricate the lid unit
25
, a metal thin film with a predetermined thickness made of stainless steel or phosphor bronze is cut in a circle form and etched to form the holes
20
b
to form the mesh structure like the cylindrical unit
21
.
Thereafter, a lid unit
25
is fabricated with its circumferential marginal portion bent so as to couple the mesh thin film to the cylindrical unit
21
.
Next, the cylindrical unit
21
and the lid unit
25
are coupled and the coupled portion is welded to fabricate the resonator
20
, and then silver or platinum or a platinum family is plated on the surface of the resonator
20
to heighten the reflectivity of light and reduce an electric resistance of the surface, thereby completing the resonator
20
.
However, the conventional resonator has the following problems.
That is, for example, first, since the rectangular thin film and the circular thin film are etched to form the holes
20
b
and welded, the fabrication process of the resonator
20
is complicated.
Secondly, if the welded portion is detached due to intense heat generated in the process that the microwave energy is switched to the light energy, the microwave may leaked outwardly.
Thirdly, when the resonator is fabricated by using the welding method, even though the welded portion is not detached, it may be oxidized to be detached due to the intense heat generated from the light bulb
5
of the resonator
20
, a long-time reliability is not guaranteed.
Fourthly, in the case that the cylindrical unit
21
of the resonator
20
is formed, since the holes
20
b
are not formed at the welded portion and the welded portion by coupling the cylindrical unit
21
and the lid unit
25
as shown in
FIG. 3B
, the light radiated from the light bulb
5
is not transmitted therethrough, causing a problem that the aperture efficiency of the whole resonator
20
is degraded and the light efficiency of the lighting apparatus is accordingly degraded.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide a resonator of a microwave lighting apparatus that is capable of preventing microwave from leaking, heightening the whole aperture efficiency and improving a light efficiency by integrally forming a portion with a mesh structure without a joint by not welding it.
Another object of the present invention is to provide a metho
Choi Joon Sik
Jeon Yong Seog
Birch & Stewart Kolasch & Birch, LLP
LG Electronics Inc.
Tran Thuy Vinh
Wong Don
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