Electric heating – Microwave heating – With control system
Reexamination Certificate
2001-05-08
2002-09-10
Walberg, Teresa (Department: 3742)
Electric heating
Microwave heating
With control system
C219S715000
Reexamination Certificate
active
06448541
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a microwave oven, and more particularly to an AC/DC type microwave oven, which is capable of using an AC (alternating current) power or a DC (direct current) power selectively.
2. Description of the Background Art
The microwave oven is an appliance for heating/cooking food using a microwave. In the microwave oven, a high voltage transformer steps up a common power source 120/230V of the AC power to a high voltage of 2,000V, and a magnetron driven by the high voltage 2,000V produces a microwave having a predetermined frequency. The microwave oscillates molecules of water in food, and then food is heated/cooked by the generated heat.
FIG. 1
is a partial cutaway perspective view of a conventional microwave oven.
In
FIG. 1
, the reference numeral
1
is a cabinet, the reference numeral
2
is a cooking chamber, and the reference numeral
3
is a device chamber. The reference numeral
4
is a door, the reference numeral
5
is a tray, and the reference numeral
6
is a cover. The cabinet
1
is partitioned into left and right spaces. At one side of the cabinet I is provided the cooking chamber
2
of which front is open. At the other side of the cabinet
2
is provided the device chamber
3
in which a variety of electrical devices are installed.
At the upper and side of the cabinet I is provided the cover
6
that forms the appearance of the microwave oven. The door
4
is fixed to one side of the cabinet I which is capable of pivoting so that the front of the cooking chamber
2
can be opened/closed thereby. The tray
5
is installed at the bottom of the cooking chamber
2
, and food to be cooked is loaded on the tray
5
. The tray
5
is rotated by a driving motor(not shown) installed at the lower side thereof.
The reference numeral
7
designates a control panel. The reference numeral
8
designates an air guide, and the reference numeral
9
designates a cooling fan. HVT, HVC, HVD and MGT designate a high voltage transformer, a high voltage condenser, a high voltage diode and a magnetron, respectively. They are installed in the device chamber
3
, and are connected electrically with each other. The high voltage transformer HVT transforms a common alternating current AC into a high voltage, and the high voltage is doubled by the high voltage condenser HVC and the high voltage diode HVD (which is 4,000V approximately). Then, the doubled high voltage is applied to the magnetron MGT, and then a 2,450 MHz (megahertz) microwave is generated by the magnetron MGT.
The control panel
7
is installed at the front side of the device chamber
3
, through which a user operates the microwave oven, and the operational state of the microwave oven is displayed.
The cooling fan
9
cools the magnetron MGT and the high voltage transformer HVT by blowing forced air. The air guide
8
is installed near the magnetron MGT so that the air heated during the cooling operation of the magnetron MGT is guided into the cooking chamber
2
.
FIG. 2
is a block diagram of AC/DC type microwave oven according to the prior art, and
FIG. 3
is a schematic diagram of FIG.
2
.
In
FIG. 2
, AC/DC type microwave oven according to the prior art includes an AC driving load
10
, a DC driving load and DC/AC converting part
20
, and a microwave oscillator
30
.
The AC driving load
10
is driven by an AC input power. The DC driving load and DC/AC converting part
20
include the DC driving load being driven by a DC input power and the DC/AC converter converting the DC input power into an AC power. The microwave oscillator
30
is inputted by the power out of the AC input power or the DC/AC power converted by a DC/AC converter, and generates a 2,450 MHz (megahertz) microwave.
With reference to
FIG. 3
, a schematic diagram of AC/DC type microwave oven is described as follows.
In
FIG. 3
, the AC input power is connected to the AC driving loads
11
, and is connected to a power switch SW
1
to determine the driving status of the AC power. The AC driving loads
11
include a lamp
12
a
and a cooling fan motor
12
b
being operated by an AC power. The DC power is connected to the DC driving loads
21
, and is connected to a power switch SW
2
to determine the driving status of the DC power, and forms a differential DC circuit net discriminated as an AC circuit net. The DC driving loads include a lamp
22
a
and a cooling fan motor
22
b
being operated by a DC power.
The DC input power is connected to the DC/AC converter
23
. The microwave oscillating part
30
includes a high voltage transformer HVT which receives both the AC power and the DC power, a high voltage condenser HVC, a high voltage diode HVD, and a magnetron MGT. The operation of the microwave oscillator is described the same way as shown in FIG.
1
.
The operation of a conventional microwave oven having the above-described constitution is as follows. First, the user pulls the door
4
so that cooking chamber
2
is opened, then places a container containing food on the tray
5
. The user closes the door
4
, switches-on the power switch SW
1
or the power switch SW
2
selectively, and then operates the microwave oven. The user, however, must switch on only one of the DC power switch SW
2
or the AC power switch SW
1
according to the input power described. For example, in case the user switches on the AC power switch SW
1
, the AC input power supplies to the driving load that includes the lamp
12
a
and the cooling fan motor
12
b
. The AC input power also supplies to the high voltage transformer HVT of the microwave oscillating part
30
. When the AC power supplied to the high voltage transformer HVT is converted to a high voltage through the high voltage condenser HVC and the high voltage diode HVD, the high voltage is supplied to the magnetron MGT. The magnetron MGT driven by the high voltage generates a microwave. The generated microwave radiates it into the cooking chamber
2
for the heating/cooking of food, and then radiates it into food uniformly when the tray
5
is rotated in the cooking chamber
2
. In the device chamber
3
, the cooling fan
9
cools the inner devices by blowing air. The tray
5
rotates the food in order to radiate the microwave on the food uniformly. Therefore, the food in the cooking chamber
2
is heated/cooked properly according to the cooking time and cooking temperature that have been selected by the user.
In case the user switches on the DC power switch SW
2
, a DC input power supplies to the driving load that includes the lamp
22
a
and the cooling fan motor
22
b
, and supplies to the DC/AC converting part
23
. The DC/AC converting part
23
converts the DC input power into an AC power, and then the converter AC power supplies to the high voltage transformer HVT of the microwave oscillating part
30
. After the converted AC power supplied to the high voltage transformer HVT is converted to a high voltage by the high voltage condenser HVC and the high voltage diode HVD, the high voltage is supplied to the magnetron MGT. The magnetron MGT driven by the high voltage generates a microwave. The generated microwave radiates it into the cooking chamber
2
for the heating/cooking of food.
In such a conventional AC/DC type microwave oven, the microwave oven must be provided with the differentiated driving loads for AC and DC, respectively. As the number of parts of the microwave increases, the manufacturing cost of the microwave oven increases.
Furthermore, in case the AC power and the DC power are selected by the user the same time mistakenly, a conventional microwave oven increases the possibility of faulty operations since a conventional microwave oven cannot prevent such an occurrence.
SUMMARY OF THE INVENTION
The present invention has been made to overcome the above described problem of the prior art, and accordingly it is the first object of the present invention to provide an AC/DC type microwave oven for reducing the manufacturing cost of the microwave oven by reducing the number of parts of the driving loads that include a la
Bushnell , Esq. Robert E.
Samsung Electronics Co,. Ltd.
Van Quang
Walberg Teresa
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