Electric heating – Microwave heating – Radiation protection
Reexamination Certificate
2003-04-16
2004-11-02
Leung, Philip H. (Department: 3742)
Electric heating
Microwave heating
Radiation protection
C219S743000, C174S034000
Reexamination Certificate
active
06812442
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a door of a microwave oven and particularly, to a door of a microwave oven, capable of preventing staining with foreign materials such as food remnants between a door frame and a choke cover and effectively chocking electromagnetic waves.
2. Description of the Related Art
Generally, a microwave oven is a cooking device for heating a cooking object by activating intermolecular movement by penetrating microwave in the cooking object.
FIG. 1
is a perspective view showing a microwave oven in accordance with the conventional art,
FIG. 2
is a sectional view taken along line I—I of
FIG. 1
,
FIG. 3
is an enlarged view of “A” portion of
FIG. 2
, and
FIG. 4
is an LC resonance circuit of the conventional microwave oven.
As shown in the drawing, the conventional microwave oven includes a casing
1
which forms a shape of the oven, a cavity
2
which is formed as a cooking space to cook food inside the casing
1
, and a door
3
which is rotatably combined with a side of the casing
1
, for opening and closing a front portion of the cavity
2
.
The casing
1
is formed in a square box, and electromagnetic generators such as a magnetron and the like are positioned at a side therein. The cavity
2
is positioned at the other side therein.
An adjusting unit
4
for selecting various cooking modes is positioned on a front surface of the casing
1
.
The door
3
is formed in a rectangular form identical as an opening portion of the cavity
2
and is positioned at the front of the casing
1
to open and close the cavity
2
.
The door panel
5
of the door
3
is generally injected with synthetic resin and on the other hand a door frame
6
is formed with iron material.
A transparent window
7
is mounted at the central opening side of the door frame
6
to look into the inside of the cavity
2
from the outside thereof.
A choke seal S for preventing leakage of electromagnetic wave is formed at an edge of the door frame
6
, and a choke cover
8
is combined with the door frame
6
to seal the choke seal S.
The usage and operation of the conventional microwave oven will be described as follows.
Firstly, a cooking object is put into the cavity
1
and the door
3
is closed. Then, when the microwave oven is operated by selecting the adjusting unit
4
, the object is heated and cooked by electromagnetic wave generated in the magnetron and radiant heat generated in a halogen heater (not shown) installed in the cavity
2
.
In the conventional microwave oven, a first capacitance C
1
for chocking electromagnetic wave generated in the magnetron is formed between an end portion
6
a
of the door frame and the front surface
1
a
of the casing, an inductance L is formed at the end portion
6
a
of the door frame, and a second capacitance C
2
is formed between the end
6
b
and a bent portion
6
c
of the door frame.
Also, the door frame
6
having a predetermined thickness is bent and formed in order to construct an LC resonance circuit. At this time, a part R having a predetermined radius is formed at the bent portion
6
c
of the door frame, so that a cap G is generated between an end portion of the choke cover
8
and the bent portion
6
c
of the door frame.
That is, in order to prevent the cap G from being generated between the end portion
8
a
of the choke cover and the bent portion
6
c
of the door frame, the end portion
8
a
of the choke cover and the adjacent bent portion
6
c
of the door frame have to be attached to each other flatly.
To this end, the choke cover
8
formed with material like synthetic resin can be fabricated with a flat shape, but the door frame
6
of iron plate material fabricated by bending has a difficulty in being fabricated with the flat shape and the bent part R can not help being generated at the bent position. According to this, even if the choke cover
8
is attached to the bent portion
6
c
of the door frame, the cap G is generated.
In case that he cap G is generated between the choke cover
8
and the bent portion
6
c
of the door frame, the gap is stained with foreign materials such as food remnants.
This phenomenon occurs more often in a large and high power (2 KW) microwave oven for company than a home microwave oven of low power (1 KW).
In case foreign materials are stained in the gap generated between the choke cover and the bent portion of the door frame, cleaning becomes very difficult and the foreign materials can not be completely removed but remain after cleaning, thus to cause hygienic severe problems.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide a door of a s microwave oven, capable of solve hygienic problems by preventing foreign materials from being stained in a gap generated between a bent portion of the door frame and a choke cover by installing a frame subsidiary plate at one side of the door frame.
Another object of the present invention is to provide a door of a microwave oven, capable of efficiently chocking electromagnetic wave generated from a magnetron by properly adjusting a size of a capacitor.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided a door of a microwave oven, including a door panel which is installed on a front surface of a casing to be opened and closed, a door frame which is inserted and combined with the door panel to be located at the front of the cavity, a transparent window which is mounted at a central opening side of the door frame to look into the inside of the cavity from the outside, a choke cover which is inserted in a bent portion of the door frame, for covering a choke seal, and a frame subsidiary plate which is installed at the door frame so as to remove a gap generated between the choke cover and the door frame.
The frame subsidiary plate includes a fixing portion which is fixed at a side of the door frame and a covering portion extended from an end of the fixing portion for covering the bent portion of the door frame.
The frame subsidiary plate maintains a predetermined space from the door frame.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is also provided a door of a microwave oven comprising: a first inductance formed at one end of a door frame; a first capacitance formed between one end of the door frame and a front side of a casing; a second inductance formed between a short surface of the door frame and a frame subsidiary plate and an end of the frame subsidiary plate; and a second capacitance between the end of the frame subsidiary plate and an end of the door frame.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 5705797 (1998-01-01), Seo
patent: 5750969 (1998-05-01), Lee
patent: 52-19341 (1977-02-01), None
Kim Eung-Soo
Kim Yang-Kyeong
Lee Young-Min
Greenblum & Bernstein P.L.C.
Leung Philip H.
LG Electronics Inc.
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