Electric lamp and discharge devices: systems – Combined load device or load device temperature modifying... – Distributed parameter resonator-type magnetron
Reexamination Certificate
2003-02-27
2004-06-29
Vu, David (Department: 2821)
Electric lamp and discharge devices: systems
Combined load device or load device temperature modifying...
Distributed parameter resonator-type magnetron
C315S039530, C315S039710
Reexamination Certificate
active
06756735
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
The present application claims priority under 35 U.S.C. §119 to Korean Application No. P2002-72436, filed Nov. 20, 2002, the entire disclosure of which is hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates in general to a magnetron which generates a microwave and, more particularly, to a magnetron and a method for joining magnetron components which can prevent vacuum leakage caused by defective joining between components.
2. Background of the Related Art
In general, a magnetron can be used in devices such as microwave ovens, plasma lighting apparatuses, dryers, and other microwave systems.
When power is applied to a magnetron, the magnetron, one of a plurality of vacuum tubes, emits thermal electrons from a cathode, which produces a microwave by interaction between a strong electric field and a magnetic field. Thus produced, the microwave is transmitted outside of the magnetron through all antenna feeder and is used as a heat source for heating all object.
The magnetron is provided with an anode having all anode cylinder and an anode vain, a cathode having a filament, a condenser, a choke coil, and leads for applying) power to the filament. A pair of magnets, a pair of pole pieces, and a yoke form a magnetic circuit. An antenna feeder and an antenna cap transmit a generated microwave outside of the magnetron.
A portion of the magnetron needs to be maintained at a vacuum. The components of this portion of the magnetron are joined together in a way that greatly affects performance of the magnetron. These components need to be joined sufficiently tightly that air cannot pass through the joints. The joints are generally made of a ceramic material component and a metal material component. To maintain proper performance of the magnetron, a technique is required for precise joining of the metal component to the ceramic component.
FIG. 1
schematically illustrates joints of filament leads and external leads of a related art magnetron.
FIG. 1
shows a pair of filament leads
15
connected to a filament
11
and a pair of external leads
22
connected to a choke coil (not shown), a lower seal
14
formed of a metal forming a part of the vacuum space, and a ceramic stem
21
.
Referring to
FIG. 1
, an upper end shield
12
and a lower end shield
13
are provided at the top and bottom, respectively, of the filament
11
. The pair of filament leads
15
is provided under the lower end shield
13
. The lower seal
14
maintains an airtight lower space on the inside of an anode cylinder (not shown). The ceramic stem
21
is provided under the lower seal
14
. The external leads
22
are connected to the choke coil and are fitted to pass through an inside of the ceramic stem
21
.
A terminal plate
23
(not shown) is provided on top of the ceramic stem
21
for connecting the pair of filament leads
15
to the pair of external leads
22
. More specifically, the terminal plate
23
is made of two pieces which are not in contract. One of the filament leads
15
and one of the external leads
22
are connected to one of the pieces of the terminal plate
23
. The other one of the filament leads
15
and the other one of the external leads
22
are connected to the other one of the pieces of the terminal plate
23
. Thus, the pair of filament leads
15
and the pair of external leads
22
are connected from opposite sides through the two pieces of the terminal plate
23
.
Because many components are joined in fabricating the foregoing related art structure, the fabricating process is very complicated. Direct brazing on the surface of the ceramic stem
21
is not possible in brazing the terminal plate
23
with a top surface of the ceramic stem
21
. Because an additional metal film is formed on the top surface of the ceramic stem before joining the terminal plate
23
by brazing, metalizing is required to form a metal film on a joining surface of the ceramic stem
21
.
Generally, because direct joining is not possible by general brazing methods, to more accurately join a metal component and a ceramic component, the metal component and the metal film part are joined by brazing after a metal film is formed on the ceramic component. That is, because the direct joining of the metal and the ceramic are not possible in the related art, a metalizing process is carried out for forming the metal film on the surface of the ceramic component to join metals.
This metalizing is a process in which a paste containing molybdenum Mo and manganese Mn is applied to a surface of the ceramic, and heated to an elevated temperature higher than 1600° C. to form the metal film on the surface of the ceramic. However, the metalizing not only complicates the fabrication process, it also increases the fabrication cost of the structure, since an additional furnace is required.
Moreover, the joining of filament leads
15
to one side of the terminal plate
23
and the joining of the external leads
22
to the other side of the terminal plate
22
requires a complicated process, which reduces the productivity of the structure.
Furthermore, the terminal plate
23
is thin and, therefore, susceptible to deformation, causing defects in the brazing of the terminal plate
23
with the ceramic Stem
21
. This also causes difficulty in correctly positioning the filament leads
15
, resulting in poor reliability and performance of the magnetron.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to a magnetron that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide a magnetron which can prevent vacuum leakage caused by defective joining between components.
Another object of the present invention is to provide a magnetron in which components can be assembled easily.
Yet another object of the present invention is to provide a method for joining components of a magnetron which can improve joining and assembly of the components.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other a advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, the magnetron includes an anode having an anode cylinder and anode vanes; a cathode having a filament; a condenser, a choke coil, and a plurality of leads for providing power to the filament; a plurality of magnets and pole pieces, and a yoke for forming a magnetic circuit; an antenna feeder and an antenna cap for transmitting a generated microwave outside of the magnetron; and a plurality of joints formed of a joining material between a metal component and a ceramic component of the magnetron, wherein the joining material is diffused between the metal component and the ceramic component, to infiltrate into an inner part of the ceramic component directly, thereby joining the metal and ceramic components.
The joint is provided at a part between an upper seal on top of the anode cylinder and an upper ceramic at a bottom of the antenna cap. The joint is further provided at a part between an exhaust pipe supporter of a metal, which supports an exhaust pipe that surrounds a top end of the antenna feeder, and an upper ceramic under the antenna cap. The joint is further provided at a part between a lower seal under the anode cylinder and a ceramic stem provided to permit pass of a plurality of leads.
The joint is further provided to an inside of an insertion hole in the ceramic stem the leads pass therethrough. The joint is further provided at a part between a filament lead connected to the filament and the external lead connected to the choke coil. The external
Lee Jong Soo
Lee Yong Soo
Park Jung Yeob
Birch & Stewart Kolasch & Birch, LLP
LG Electronics Inc.
Vu David
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