Electric heating – Microwave heating – With diverse-type heating
Reexamination Certificate
2002-10-25
2004-03-30
Leung, Philip H. (Department: 3742)
Electric heating
Microwave heating
With diverse-type heating
C219S732000, C219S763000, C126S33700R, C312S236000
Reexamination Certificate
active
06713740
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATION
This application claims the benefit of Korean Application No. 2002-49034, filed Aug. 19, 2002, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a microwave oven, and more particularly, to a microwave oven which is designed such that an upper heater and one or more middle heaters are installed at upper and middle portions in a cooking cavity, respectively, and food holding members are slidably provided between the upper and middle heaters and between the middle heaters and a bottom of the cooking cavity, respectively, thus heating the upper and lower parts of the food at the same time, and cooking one or more foods at the same time.
2. Description of the Related Art
A microwave oven is an appliance which cooks and/or heats food laid in a cooking cavity using high-frequency electromagnetic waves generated by an oscillation of a magnetron installed in a machine room. That is, the high-frequency electromagnetic waves penetrate food laid in the cooking cavity so as to repeatedly change a molecular arrangement of moisture in the food. The food is cooked by frictional heat generated by molecules.
However, when food is cooked using only the high-frequency electromagnetic waves, the high-frequency electromagnetic waves do not uniformly penetrate the food. Instead penetration of the food is according to content or distribution of the moisture of the food and a size of the food. Thus, the food is not satisfactorily cooked when using only the high-frequency electromagnetic waves and to cook the food in a variety of manners may not be possible. In order to solve such problems, a microwave oven is provided with a heater at an upper portion in a cooking cavity thereof, thus cooking the food by high-frequency electromagnetic waves, and rapidly and uniformly cooking the food by heat generated from the heater, as well as browning a surface of the food by heat of a high temperature generated from the heater.
FIG. 1
schematically shows a conventional microwave oven having a heater at an upper portion of a cooking cavity. As shown in
FIG. 1
, the conventional microwave oven comprises a cooking cavity
1
and a machine room
2
. The cooking cavity
1
defines a space for cooking food. Several electrical devices, including a magnetron
3
to generate high-frequency electromagnetic waves, are installed in the machine room
2
.
A heater
4
heating the food to be cooked is installed at the upper portion of the cooking cavity
1
. A turntable-type cooking tray
5
is installed at a lower portion of the cooking cavity
1
. A motor
6
to rotate the turntable-type cooking tray
5
is installed under a bottom of the cooking cavity
1
. The food to be cooked is laid on the turntable-type cooking tray
5
, and the motor
6
rotates the turntable-type cooking tray
5
.
The method of cooking the food using a conventional microwave oven constructed, as above described, is as follows. As the magnetron
3
and the motor
6
are operated, the cooking tray
5
on which the food is laid is rotated at a low speed. At this time, high-frequency electromagnetic waves penetrate the food to cook the food. Further, when the heater
4
installed at the upper portion in the cooking cavity
1
is operated, the food is cooked by heat generated from the heater
4
. As such, when the heater
4
and the magnetron
3
are operated at the same time, the food is rapidly cooked by the heat of the heater
4
and the high-frequency electromagnetic waves.
However, since the conventional microwave oven is provided at the upper portion in the cooking cavity with only one heater, the distance between the heater and the food is large in the case of cooking small-sized food, so heat generated from the heater is not effectively transmitted to the food. Moreover, since heat is not sufficiently transmitted to a lower part of the food, the food must be turned upside down during a cooking process so as to desirably cook and brown the lower part of the food, thereby making cooking the food inconvenient using the conventional microwave oven.
Further, since the conventional microwave oven is designed such that the cooking cavity forms a single cooking space to cook the food, which is laid on the cooking tray, cooking several foods at one time, is not possible so cooking the food takes a long time.
SUMMARY OF THE INVENTION
Accordingly, it is an aspect of the present invention to provide a microwave oven, which is designed to heat upper and lower parts of food at a same time so that turning the food upside down during a cooking process is not needed.
Another aspect is to provide a microwave oven, which is designed to removably mount one or more food holding members in a cooking cavity, thus cooking several foods at a same time.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
In order to accomplish the above and other aspects, a microwave oven, comprising a cooking cavity defined by a rear wall, sidewalls, an upper wall and a bottom wall, and a cooking tray installed on the bottom wall of the cooking cavity, wherein an upper heater is installed at a position adjacent to the upper wall of the cooking cavity, and one or more middle heaters are rotatably installed on the rear wall at positions between the upper heater and the cooking tray, upper supports are provided between the upper heater and the middle heaters so as to horizontally protrude from each of the sidewalls, and lower supports are provided between the middle heaters and the cooking tray so as to horizontally protrude from each of the sidewalls, whereby a food holding unit is removably mounted on the upper and lower supports.
In the microwave oven, a projection is provided on a sidewall of the cooking cavity at a position above the upper supports so as to protrude by a predetermined length toward a center of the cooking cavity, thus preventing the food holding unit from tilting downwards and falling to the floor when the food holding unit slides out of the cooking cavity.
In the cooking cavity, a vertical step is provided at a position between the upper and lower supports so as to be positioned at a front portion of a sidewall of the cooking cavity, thus preventing the food holding unit from colliding with the middle heaters when putting the food holding unit between the upper and lower supports.
The food holding unit comprises a first food holding member fabricated in a form of a wire rack and a second food holding member fabricated in a form of a tray.
A tube made of a nonconductive and heat-resistant material is fitted over each side end of the first food holding member so that the tube comes into contact with the upper supports or the lower supports when the first food holding member is mounted in the cooking cavity, thus preventing sparks from arcing between the first food holding member and the upper supports or the lower supports, and allowing the first food holding member to smoothly slide in and out of the cooking cavity.
A stopper having a predetermined length extends from a central portion of each of front and rear ends of the first food holding member, thus allowing the first food holding member to be spaced apart from the rear wall of the cooking cavity by a predetermined length.
A flange downwardly extends along an edge of the second food holding member to have a predetermined width so that the flange lays on the upper supports or the lower supports when the second food holding member slides in and out of the cooking cavity.
At least one tube made of a nonconductive and heat-resistant material is fitted over a lower end of the flange so that the tube comes into contact with the upper supports or the lower supports when the second food holding member is mounted in the cooking cavity, thus preventing sparks from arcing between th
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