CA2327721A1 - Turntable motor driving circuit for a direct current microwave oven - Google Patents
Turntable motor driving circuit for a direct current microwave oven Download PDFInfo
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- CA2327721A1 CA2327721A1 CA 2327721 CA2327721A CA2327721A1 CA 2327721 A1 CA2327721 A1 CA 2327721A1 CA 2327721 CA2327721 CA 2327721 CA 2327721 A CA2327721 A CA 2327721A CA 2327721 A1 CA2327721 A1 CA 2327721A1
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- voltage
- turntable motor
- driving circuit
- microwave oven
- power supply
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B6/00—Heating by electric, magnetic or electromagnetic fields
- H05B6/64—Heating using microwaves
- H05B6/6408—Supports or covers specially adapted for use in microwave heating apparatus
- H05B6/6411—Supports or covers specially adapted for use in microwave heating apparatus the supports being rotated
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B6/00—Heating by electric, magnetic or electromagnetic fields
- H05B6/64—Heating using microwaves
- H05B6/80—Apparatus for specific applications
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- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Control Of High-Frequency Heating Circuits (AREA)
- Electric Ovens (AREA)
- Constitution Of High-Frequency Heating (AREA)
- Inverter Devices (AREA)
Abstract
A turntable motor driving circuit for a DC microwave oven using a low-priced AC motor as a turntable motor. The turntable motor driving circuit includes: a control unit for generating a driving control pulse for a DC into an AC
according to an initialization input of a cooking function;
an inverter means for inverting a DC voltage of a DC power supply into an AC voltage by receiving the driving control pulse from the control unit; a transformation means for transforming the AC voltage inverted by the inverter unit into a predetermined voltage required for motor driving;
and a turntable motor consisting of an AC motor, and being driven by the AC voltage transformed by the transformation means.
according to an initialization input of a cooking function;
an inverter means for inverting a DC voltage of a DC power supply into an AC voltage by receiving the driving control pulse from the control unit; a transformation means for transforming the AC voltage inverted by the inverter unit into a predetermined voltage required for motor driving;
and a turntable motor consisting of an AC motor, and being driven by the AC voltage transformed by the transformation means.
Description
TURNTABLE MOTOR DRIVING CIRCUIT FOR A DIRECT CURRENT
MICROWAVE OVEN
BACKGROUND OF THE INVENTION
1. Field of the Invention The present invention relates to a turntable motor driving circuit for a direct current microwave oven, and more particularly to an improved turntable motor driving circuit for a direct current(DC) microwave oven which can 1o use a general alternating current(AC) motor as a turntable driving motor.
MICROWAVE OVEN
BACKGROUND OF THE INVENTION
1. Field of the Invention The present invention relates to a turntable motor driving circuit for a direct current microwave oven, and more particularly to an improved turntable motor driving circuit for a direct current(DC) microwave oven which can 1o use a general alternating current(AC) motor as a turntable driving motor.
2. Description of the Related Art As publicly known, a microwave oven generates microwave of about 2,450MHz per second by utilizing a magnetron in order to heat/cook food. Frictional heat is generated by changing a molecule alignment direction of the food to be cooked hundreds of thousands times per second due to the microwave, so that the food is heated/cooked by 2o the frictional heat.
In the microwave oven, a high voltage of about 2KV is boosted from a rated commercial AC power supply by a high voltage, and then doubled into a high voltage of 4KV by a voltage doubling circuit and supplied to the magnetron.
Therefore, the magnetron generates a high frequency microwave.
FIG. 1 is a circuit diagram illustrating a general power supply driving device for an AC microwave. The power supply driving device includes a primary switch 10, a door lamp 12, a fan motor 16, a turntable motor 20, a first to a third relay switches 14, 18, and 22, a high voltage transformer 24, a high voltage capacitor HVC, a high voltage diode HVD, and a magnetron MGT.
1o The primary switch 10 is switched on by a close operation of a cooking chamber door, so that an AC voltage is supplied from the commercial alternating current power supply AC to a primary coil 24a of the high voltage transformer 24.
The door lamp 12 is turned on to illuminate a cooking chamber by receiving the commercial AC utility power supply AC, when a door sensing switch (not shown) is switched off by opening of the cooking chamber door, and the first relay switch 14 is inversely switched on.
2o The fan motor 16 serves to ventilate a cooking chamber and prevents the magnetron MGT from heat generation during the cooking operation. At a state that the primary switch 10 is switched on, if the second relay switch 18 is switched on when a certain cooking function is performed, the fan motor 16 is driven by receiving the commercial AC
power supply.
The turntable motor 20 is an AC driving motor, disposed at a lower portion of the cooking chamber, for rotating a turntable which supports a vessel containing the food. At a state that the primary switch 10 is switched on, if the third relay switch 22 is switched on together with the second relay switch 18 when a certain cooking function is performed, the turntable motor 20 is driven by the 1o commercial AC power supply AC.
On the other hand, the high voltage transformer 24 receives the AC utility power supply through the primary coil 24a thereof, and generates a high voltage corresponding to respective winding ratios through a secondary coil 24b thereof, according to the switch-on operation of the primary switch 10. The voltage doubling circuit consisting of the high voltage capacitor HVC and the high voltage diode HVD doubles the high voltage generated from the high voltage transformer 24, and 2o supplies the doubled high voltage to the magnetron MGT.
The operation of the conventional power supply driving device for the AC microwave oven will be now described.
When the door sensing switch is switched off according as the cooking chamber door is open by a user, the first relay switch 14 is inversely switched on, then the door lamp 12 is turned to light on by receiving the commercial AC power supply AC. Here, since the primary switch 10 maintains a switched-off state, the high voltage transformer 24 does not receive the commercial AC power supply AC. Accordingly, the high voltage transformer 24 cannot perform the operation for generating the high voltage.
Conversely, when the cooking chamber door is closed and the primary switch 10 is switched on, the high voltage 1o transformer 24 receives the AC power supply AC, and thus the microwave oven is prepared for the operation of the cooking function.
At this time, when the user operates a certain cooking function, the magnetron MGT is driven to generate a microwave, simultaneous with driving the fan motor 16 and the turntable motor 20 by the switched-on of the second relay switch 18 and the third relay switch 22. Therefore, the food rotated on the turntable in the cooking chamber is heated/cooked by the microwave generated from the magnetron MGT.
Meanwhile, since the conventional power supply driving device for the conventional AC microwave oven is designed to be driven merely by the AC power supply, and thus cannot be used in the fields, vehicles, ships and airplanes where the AC power supply is difficult to be supplied.
In order to overcome such a disadvantage, there has been suggested a DC microwave oven having an inverter for inverting the DC such as a portable battery power supply, which can be utilized in various transportations including vehicles and in the fields, into the AC.
In the DC microwave oven, a door lamp and a fan motor are driven directly by the DC power supply, while a DC
1o motor is utilized as a turntable motor for driving a turntable in a cooking chamber to be driven by the DC power supply.
However, since the DC microwave oven employs the high-priced DC motor as the turntable motor for driving the turntable, the whole manufacturing cost of the DC microwave oven is increased. As a result, consumers must pay additional increased cost for purchasing the DC microwave oven.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a turntable motor driving circuit for a DC
microwave oven which the manufacturing cost can be remarkably reduced by using a low-priced AC motor as a turntable motor for the DC microwave oven and driving the turntable motor by inverting a DC power supply into an AC
power supply.
Another object of the present invention is to provide a turntable motor driving circuit for a DC microwave oven which can easily generate a DC power supply required for other driving circuit terminals through the driving circuit for driving an AC motor as the turntable motor.
In order to achieve the above-described obj ects of the 1o present invention, there is provided a turntable motor driving circuit for a DC microwave oven including: a control unit for generating a driving control pulse for inverting a DC into an AC according to an input to start a cooking function; an inverter unit for inverting a DC
voltage of the DC power supply into an AC voltage by receiving the driving control pulse from the control unit;
a transformation unit for transforming the AC voltage inverted by the inverter unit into a predetermined voltage;
and a turntable motor having an AC motor, and being driven 2o by the AC voltage transformed by the transformation unit.
Preferably, the driving control pulse from the control unit includes a plurality of pulse signals whose periods are alternately inverted, and the inverter unit includes a plurality of power transistors to be alternately turned on/off by respectively receiving the plurality of driving control pulses.
More preferably, in accordance with one aspect of the present invention, the turntable motor driving circuit for the DC microwave oven further includes: a rectification section for rectifying the AC voltage induced by the transformation unit; and a voltage regulator for regulating and outputting the DC voltage rectified by the rectification section. Here, the voltage by the voltage 1o regulator is supplied to other operation circuit terminals as an operation power supply.
In accordance with the present invention, the whole manufacturing cost of a microwave oven is remarkably reduced by using the low-priced AC motor as the turntable motor which rotates the turntable where food is mounted, which results in reduction of the purchase price of the microwave oven.
BRIEF DESCRIPTION OF THE DRAWINGS
2o The present invention will become better understood with reference to the accompanying drawings which are given only by way of illustration and thus are not limitative of the present invention, wherein:
_g_ FIG. 1 is a circuit diagram illustrating a general power supply driving device for an AC microwave oven;
FIG. 2 is a circuit diagram illustrating a turntable motor driving circuit for a DC microwave oven in accordance with a preferred embodiment of the present invention; and FIG. 3 is a waveform diagram for explaining an operation of inverting a direct current into an alternating current in order to drive a turntable motor in accordance with the preferred embodiment of the present invention.
to DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
A turntable motor driving circuit for a DC microwave oven in accordance with the present invention will be described in detail with reference to the accompanying drawings.
FIG. 2 is a circuit diagram illustrating the turntable motor driving circuit for the DC microwave oven in accordance with a preferred embodiment of the present invention. The turntable motor driving circuit includes a 2o DC power supply 30 for generating a DC voltage of about 12V, a door lamp 32, and a fan motor 36. The door lamp 32 and the fan motor 36 are respectively turned on to illuminate and driven to be rotated by receiving the DC
voltage from the DC power supply 30 according to switching operations of a first relay switch 34 and a second relay switch 38.
The turntable motor driving circuit also includes a door sensing switch DSW for sensing an open/close operation of door of a microwave oven, and performing a switching operation, a driving circuit 46 for generating alternate driving pulses at predetermined intervals according to the switching operation of the door sensing switch DSW and first and second field effect transistors 48 and 50 for 1o respectively receiving the alternate driving pulses from the driving circuit 46, and performing an alternate ON/OFF
operation.
In addition, the turntable motor driving circuit includes a high voltage transformer 52 for receiving the DC power supply from the battery power supply 30 through primary coil 52a thereof and transforming the DC power supply into a high voltage AC power supply through secondary coil 52b, in accordance with the alternate ON/OFF
operation of the first and second field effect transistors 48 and 50, and first and second interlock switches SWl and SW2, switched according to the open/close state of the cooking chamber door, for allowing or preventing the DC
voltage from supplying from the high voltage transformer 52.
There are also provided a high voltage capacitor HVC
and a high voltage diode HVD for doubling a high voltage AC, a surge interrupt capacitor SC for interrupting a surge voltage induced by the high voltage transformer 52, and a magnetron MGT for generating a microwave by receiving the AC voltage doubled by the high voltage capacitor HVC and the high voltage diode HVD.
According to an aspect of the preferred embodiment of the present invention, a microcomputer 54, first and second to power transistors 56 and 58 and a transformer 60 as a push-pull circuit, and an AC motor as a turntable motor are used. In addition, a bridge diode 64 and a voltage regulator 66 are utilized so as for respectively rectifying and regulating the AC voltage from the transformation unit 60 .
On the other hand, the microcomputer 54 controls a cooking state of food according to an input of a function button by the user. In addition, the microcomputer 54 alternately generates first and second driving control pulses whose periods are inverted for predetermined intervals through a first and second control output terminals E1 and E2, thereby alternately turns on/off the first and second power transistors 56 and 58.
The first and second power transistors 56 and 58 are alternately turned on/off by receiving the first and second driving control pulses from the first and second control output terminals E1 and E2 of the microcomputer 54 through respective base terminals of the first and second power transistors 56 and 58.
The transformer 60 receives, for example, a DC voltage of 12V from the DC power supply 30 through the primary coil 60a, and transforms the DC voltage into an AC voltage of l0 21V required for driving the turntable motor 62 through secondary coil 60b, in accordance with the alternate ON/OFF
operation of the first and second power transistors 56 and 58.
The turntable motor 62 of an AC motor receives the AC
voltage of 21V which is transformed by the transformer 60, and rotates a turntable (not shown) in a cooking chamber.
Meanwhile, the bridge diode 64 rectifies and outputs the AC voltage from the transformer 60, and the voltage regulator 66 converts the rectified DC voltage into a 2o constant voltage of 15V which is supplied to one terminal of the door sensing switch DSW.
Accordingly, the driving circuit 46 is driven by receiving the DC voltage of 15V from the voltage regulator 66 through a power supply terminal Vcc according to the switch-on state of the door sensing switch DSW.
The operation of the turntable motor driving circuit for the DC microwave oven of the present invention will be described in detail with reference to FIGS. 2 and 3.
When the cooking chamber door (not shown) of the DC
microwave oven is open, the door sensing switch DSW senses the open of the cooking chamber door and is switched off.
Accordingly, the first relay switch 34 is switched on, and to thus the door lamp 32 is lighted by receiving the DC
voltage from the DC power supply 30.
In addition, when the cooking chamber door is open, the first and second interlock switches SWl and Sw2 are switched on, and thus interrupts the application of the DC
voltage to the primary coil 52a of the high voltage transformer 52.
In this state, when the cooking chamber door is closed after positioning the food on the turntable in the cooking chamber, the door sensing switch DSW is switched on by 2o sensing the close of the cooking chamber door. Accordingly, the first relay switch 34 is switched off, and thus the door lamp 32 is turned off.
On the other hand, at a state that the door sensing switch DSW is switched on, a certain function button (not shown) for commanding to start cooking is inputted, the microcomputer 54 generates the first and second driving control pulses whose periods are alternately inverted through the first and second control output terminals El and E2 (See FIG. 3).
In addition, the first and second power transistors 56 and 58 respectively receive the first and second driving control pulses through their respective base terminals, and are alternately turned on/off at predetermined intervals.
to Accordingly, in the transformer 60, the DC voltage of 12V from the DC power supply 30 is supplied to the primary coil 60a, and then the transformed AC voltage of 21V is induced through the secondary coil 60b (See FIG. 3).
As a result, the turntable motor 62 of an AC motor receives the AC voltage of 21V from the transformer 60, and rotates the turntable where the food is positioned.
Here, the bridge diode 64 rectifies the AC voltage of 21V induced through the secondary coil 60b of the transformer 60, and the voltage regulator 66 regulates the rectified DC voltage to a constant direct current voltage of 15V.
The driving circuit 46 is driven by receiving the DC
voltage of 15V from the voltage regulator 66 through the power supply terminal Vcc via the door sensing switch DSW, and generates the first and second driving control pulses whose high pulses are alternately inverted through the first and second output terminals 01 and 02.
Therefore, the first and second field effect transistors 48 and 50 respectively receive the first and second driving control pulses through their base terminals, and are alternately turned on/off in order for allowing the AC voltage to be induced to the primary coil 52a of the high voltage transformer 52.
1o On the other hand, the high voltage transformer 52 generates a high AC voltage through the secondary coil 52b according to a winding ratio with the primary coil 52a, and thus the surge voltage is vanished by the surge voltage interrupt capacitor SC. Therefore, the magnetron MGT
receives the high voltage AC doubled by the high voltage capacitor HVC and the high voltage diode HVD, and generates the microwave.
As a result, the microwave generated from the magnetron MGT heats/cooks the food on the turntable while 2o being rotated by the turntable motor 62 of an AC motor.
According to the present invention constructed as above, since a low-priced AC motor can be employed to a DC
microwave oven as a turntable motor which rotates a turntable, whole manufacturing cost of the DC microwave oven can be remarkably reduced results in reduction of the purchase price of the DC microwave oven.
While the present invention has been particularly shown and described with reference to the preferred embodiment thereof, it will be understood by those skilled in the art that various changes in form and details may be effected therein without departing from the sprit and scope of the present invention as defined by the appended claims.
In the microwave oven, a high voltage of about 2KV is boosted from a rated commercial AC power supply by a high voltage, and then doubled into a high voltage of 4KV by a voltage doubling circuit and supplied to the magnetron.
Therefore, the magnetron generates a high frequency microwave.
FIG. 1 is a circuit diagram illustrating a general power supply driving device for an AC microwave. The power supply driving device includes a primary switch 10, a door lamp 12, a fan motor 16, a turntable motor 20, a first to a third relay switches 14, 18, and 22, a high voltage transformer 24, a high voltage capacitor HVC, a high voltage diode HVD, and a magnetron MGT.
1o The primary switch 10 is switched on by a close operation of a cooking chamber door, so that an AC voltage is supplied from the commercial alternating current power supply AC to a primary coil 24a of the high voltage transformer 24.
The door lamp 12 is turned on to illuminate a cooking chamber by receiving the commercial AC utility power supply AC, when a door sensing switch (not shown) is switched off by opening of the cooking chamber door, and the first relay switch 14 is inversely switched on.
2o The fan motor 16 serves to ventilate a cooking chamber and prevents the magnetron MGT from heat generation during the cooking operation. At a state that the primary switch 10 is switched on, if the second relay switch 18 is switched on when a certain cooking function is performed, the fan motor 16 is driven by receiving the commercial AC
power supply.
The turntable motor 20 is an AC driving motor, disposed at a lower portion of the cooking chamber, for rotating a turntable which supports a vessel containing the food. At a state that the primary switch 10 is switched on, if the third relay switch 22 is switched on together with the second relay switch 18 when a certain cooking function is performed, the turntable motor 20 is driven by the 1o commercial AC power supply AC.
On the other hand, the high voltage transformer 24 receives the AC utility power supply through the primary coil 24a thereof, and generates a high voltage corresponding to respective winding ratios through a secondary coil 24b thereof, according to the switch-on operation of the primary switch 10. The voltage doubling circuit consisting of the high voltage capacitor HVC and the high voltage diode HVD doubles the high voltage generated from the high voltage transformer 24, and 2o supplies the doubled high voltage to the magnetron MGT.
The operation of the conventional power supply driving device for the AC microwave oven will be now described.
When the door sensing switch is switched off according as the cooking chamber door is open by a user, the first relay switch 14 is inversely switched on, then the door lamp 12 is turned to light on by receiving the commercial AC power supply AC. Here, since the primary switch 10 maintains a switched-off state, the high voltage transformer 24 does not receive the commercial AC power supply AC. Accordingly, the high voltage transformer 24 cannot perform the operation for generating the high voltage.
Conversely, when the cooking chamber door is closed and the primary switch 10 is switched on, the high voltage 1o transformer 24 receives the AC power supply AC, and thus the microwave oven is prepared for the operation of the cooking function.
At this time, when the user operates a certain cooking function, the magnetron MGT is driven to generate a microwave, simultaneous with driving the fan motor 16 and the turntable motor 20 by the switched-on of the second relay switch 18 and the third relay switch 22. Therefore, the food rotated on the turntable in the cooking chamber is heated/cooked by the microwave generated from the magnetron MGT.
Meanwhile, since the conventional power supply driving device for the conventional AC microwave oven is designed to be driven merely by the AC power supply, and thus cannot be used in the fields, vehicles, ships and airplanes where the AC power supply is difficult to be supplied.
In order to overcome such a disadvantage, there has been suggested a DC microwave oven having an inverter for inverting the DC such as a portable battery power supply, which can be utilized in various transportations including vehicles and in the fields, into the AC.
In the DC microwave oven, a door lamp and a fan motor are driven directly by the DC power supply, while a DC
1o motor is utilized as a turntable motor for driving a turntable in a cooking chamber to be driven by the DC power supply.
However, since the DC microwave oven employs the high-priced DC motor as the turntable motor for driving the turntable, the whole manufacturing cost of the DC microwave oven is increased. As a result, consumers must pay additional increased cost for purchasing the DC microwave oven.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a turntable motor driving circuit for a DC
microwave oven which the manufacturing cost can be remarkably reduced by using a low-priced AC motor as a turntable motor for the DC microwave oven and driving the turntable motor by inverting a DC power supply into an AC
power supply.
Another object of the present invention is to provide a turntable motor driving circuit for a DC microwave oven which can easily generate a DC power supply required for other driving circuit terminals through the driving circuit for driving an AC motor as the turntable motor.
In order to achieve the above-described obj ects of the 1o present invention, there is provided a turntable motor driving circuit for a DC microwave oven including: a control unit for generating a driving control pulse for inverting a DC into an AC according to an input to start a cooking function; an inverter unit for inverting a DC
voltage of the DC power supply into an AC voltage by receiving the driving control pulse from the control unit;
a transformation unit for transforming the AC voltage inverted by the inverter unit into a predetermined voltage;
and a turntable motor having an AC motor, and being driven 2o by the AC voltage transformed by the transformation unit.
Preferably, the driving control pulse from the control unit includes a plurality of pulse signals whose periods are alternately inverted, and the inverter unit includes a plurality of power transistors to be alternately turned on/off by respectively receiving the plurality of driving control pulses.
More preferably, in accordance with one aspect of the present invention, the turntable motor driving circuit for the DC microwave oven further includes: a rectification section for rectifying the AC voltage induced by the transformation unit; and a voltage regulator for regulating and outputting the DC voltage rectified by the rectification section. Here, the voltage by the voltage 1o regulator is supplied to other operation circuit terminals as an operation power supply.
In accordance with the present invention, the whole manufacturing cost of a microwave oven is remarkably reduced by using the low-priced AC motor as the turntable motor which rotates the turntable where food is mounted, which results in reduction of the purchase price of the microwave oven.
BRIEF DESCRIPTION OF THE DRAWINGS
2o The present invention will become better understood with reference to the accompanying drawings which are given only by way of illustration and thus are not limitative of the present invention, wherein:
_g_ FIG. 1 is a circuit diagram illustrating a general power supply driving device for an AC microwave oven;
FIG. 2 is a circuit diagram illustrating a turntable motor driving circuit for a DC microwave oven in accordance with a preferred embodiment of the present invention; and FIG. 3 is a waveform diagram for explaining an operation of inverting a direct current into an alternating current in order to drive a turntable motor in accordance with the preferred embodiment of the present invention.
to DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
A turntable motor driving circuit for a DC microwave oven in accordance with the present invention will be described in detail with reference to the accompanying drawings.
FIG. 2 is a circuit diagram illustrating the turntable motor driving circuit for the DC microwave oven in accordance with a preferred embodiment of the present invention. The turntable motor driving circuit includes a 2o DC power supply 30 for generating a DC voltage of about 12V, a door lamp 32, and a fan motor 36. The door lamp 32 and the fan motor 36 are respectively turned on to illuminate and driven to be rotated by receiving the DC
voltage from the DC power supply 30 according to switching operations of a first relay switch 34 and a second relay switch 38.
The turntable motor driving circuit also includes a door sensing switch DSW for sensing an open/close operation of door of a microwave oven, and performing a switching operation, a driving circuit 46 for generating alternate driving pulses at predetermined intervals according to the switching operation of the door sensing switch DSW and first and second field effect transistors 48 and 50 for 1o respectively receiving the alternate driving pulses from the driving circuit 46, and performing an alternate ON/OFF
operation.
In addition, the turntable motor driving circuit includes a high voltage transformer 52 for receiving the DC power supply from the battery power supply 30 through primary coil 52a thereof and transforming the DC power supply into a high voltage AC power supply through secondary coil 52b, in accordance with the alternate ON/OFF
operation of the first and second field effect transistors 48 and 50, and first and second interlock switches SWl and SW2, switched according to the open/close state of the cooking chamber door, for allowing or preventing the DC
voltage from supplying from the high voltage transformer 52.
There are also provided a high voltage capacitor HVC
and a high voltage diode HVD for doubling a high voltage AC, a surge interrupt capacitor SC for interrupting a surge voltage induced by the high voltage transformer 52, and a magnetron MGT for generating a microwave by receiving the AC voltage doubled by the high voltage capacitor HVC and the high voltage diode HVD.
According to an aspect of the preferred embodiment of the present invention, a microcomputer 54, first and second to power transistors 56 and 58 and a transformer 60 as a push-pull circuit, and an AC motor as a turntable motor are used. In addition, a bridge diode 64 and a voltage regulator 66 are utilized so as for respectively rectifying and regulating the AC voltage from the transformation unit 60 .
On the other hand, the microcomputer 54 controls a cooking state of food according to an input of a function button by the user. In addition, the microcomputer 54 alternately generates first and second driving control pulses whose periods are inverted for predetermined intervals through a first and second control output terminals E1 and E2, thereby alternately turns on/off the first and second power transistors 56 and 58.
The first and second power transistors 56 and 58 are alternately turned on/off by receiving the first and second driving control pulses from the first and second control output terminals E1 and E2 of the microcomputer 54 through respective base terminals of the first and second power transistors 56 and 58.
The transformer 60 receives, for example, a DC voltage of 12V from the DC power supply 30 through the primary coil 60a, and transforms the DC voltage into an AC voltage of l0 21V required for driving the turntable motor 62 through secondary coil 60b, in accordance with the alternate ON/OFF
operation of the first and second power transistors 56 and 58.
The turntable motor 62 of an AC motor receives the AC
voltage of 21V which is transformed by the transformer 60, and rotates a turntable (not shown) in a cooking chamber.
Meanwhile, the bridge diode 64 rectifies and outputs the AC voltage from the transformer 60, and the voltage regulator 66 converts the rectified DC voltage into a 2o constant voltage of 15V which is supplied to one terminal of the door sensing switch DSW.
Accordingly, the driving circuit 46 is driven by receiving the DC voltage of 15V from the voltage regulator 66 through a power supply terminal Vcc according to the switch-on state of the door sensing switch DSW.
The operation of the turntable motor driving circuit for the DC microwave oven of the present invention will be described in detail with reference to FIGS. 2 and 3.
When the cooking chamber door (not shown) of the DC
microwave oven is open, the door sensing switch DSW senses the open of the cooking chamber door and is switched off.
Accordingly, the first relay switch 34 is switched on, and to thus the door lamp 32 is lighted by receiving the DC
voltage from the DC power supply 30.
In addition, when the cooking chamber door is open, the first and second interlock switches SWl and Sw2 are switched on, and thus interrupts the application of the DC
voltage to the primary coil 52a of the high voltage transformer 52.
In this state, when the cooking chamber door is closed after positioning the food on the turntable in the cooking chamber, the door sensing switch DSW is switched on by 2o sensing the close of the cooking chamber door. Accordingly, the first relay switch 34 is switched off, and thus the door lamp 32 is turned off.
On the other hand, at a state that the door sensing switch DSW is switched on, a certain function button (not shown) for commanding to start cooking is inputted, the microcomputer 54 generates the first and second driving control pulses whose periods are alternately inverted through the first and second control output terminals El and E2 (See FIG. 3).
In addition, the first and second power transistors 56 and 58 respectively receive the first and second driving control pulses through their respective base terminals, and are alternately turned on/off at predetermined intervals.
to Accordingly, in the transformer 60, the DC voltage of 12V from the DC power supply 30 is supplied to the primary coil 60a, and then the transformed AC voltage of 21V is induced through the secondary coil 60b (See FIG. 3).
As a result, the turntable motor 62 of an AC motor receives the AC voltage of 21V from the transformer 60, and rotates the turntable where the food is positioned.
Here, the bridge diode 64 rectifies the AC voltage of 21V induced through the secondary coil 60b of the transformer 60, and the voltage regulator 66 regulates the rectified DC voltage to a constant direct current voltage of 15V.
The driving circuit 46 is driven by receiving the DC
voltage of 15V from the voltage regulator 66 through the power supply terminal Vcc via the door sensing switch DSW, and generates the first and second driving control pulses whose high pulses are alternately inverted through the first and second output terminals 01 and 02.
Therefore, the first and second field effect transistors 48 and 50 respectively receive the first and second driving control pulses through their base terminals, and are alternately turned on/off in order for allowing the AC voltage to be induced to the primary coil 52a of the high voltage transformer 52.
1o On the other hand, the high voltage transformer 52 generates a high AC voltage through the secondary coil 52b according to a winding ratio with the primary coil 52a, and thus the surge voltage is vanished by the surge voltage interrupt capacitor SC. Therefore, the magnetron MGT
receives the high voltage AC doubled by the high voltage capacitor HVC and the high voltage diode HVD, and generates the microwave.
As a result, the microwave generated from the magnetron MGT heats/cooks the food on the turntable while 2o being rotated by the turntable motor 62 of an AC motor.
According to the present invention constructed as above, since a low-priced AC motor can be employed to a DC
microwave oven as a turntable motor which rotates a turntable, whole manufacturing cost of the DC microwave oven can be remarkably reduced results in reduction of the purchase price of the DC microwave oven.
While the present invention has been particularly shown and described with reference to the preferred embodiment thereof, it will be understood by those skilled in the art that various changes in form and details may be effected therein without departing from the sprit and scope of the present invention as defined by the appended claims.
Claims (4)
1. A turntable motor driving circuit for a DC
microwave oven, comprising:
a control means for generating a driving control pulse for inverting a DC into an AC according to an input to start a cooking function;
an inverter means for inverting a DC voltage of the DC power supply into an AC voltage by receiving the driving control pulse from the control means;
a transformation means for transforming the AC voltage inverted by the inverter means into a predetermined voltage; and a turntable motor comprising an AC motor, and being driven by the AC voltage transformed by the transformation means.
microwave oven, comprising:
a control means for generating a driving control pulse for inverting a DC into an AC according to an input to start a cooking function;
an inverter means for inverting a DC voltage of the DC power supply into an AC voltage by receiving the driving control pulse from the control means;
a transformation means for transforming the AC voltage inverted by the inverter means into a predetermined voltage; and a turntable motor comprising an AC motor, and being driven by the AC voltage transformed by the transformation means.
2. The turntable motor driving circuit as claimed in claim 1, wherein:
the driving control pulse from the control means comprises a plurality of pulse signals whose periods are alternately inverted; and the inverter means comprises a plurality of power transistors to be alternately turned on/off by respectively receiving the plurality of driving control pulses.
the driving control pulse from the control means comprises a plurality of pulse signals whose periods are alternately inverted; and the inverter means comprises a plurality of power transistors to be alternately turned on/off by respectively receiving the plurality of driving control pulses.
3. The turntable motor driving circuit as claimed in claim 1, further comprising:
a rectification section for rectifying the AC voltage induced by the transformation means; and a voltage regulator for regulating and outputting the DC voltage rectified by the rectification section.
a rectification section for rectifying the AC voltage induced by the transformation means; and a voltage regulator for regulating and outputting the DC voltage rectified by the rectification section.
4. The turntable motor driving circuit as claimed in claim 3, wherein the voltage regulated by the voltage regulator is supplied to other operation circuit terminals as an operation power supply.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR1019990056266A KR20010055165A (en) | 1999-12-09 | 1999-12-09 | Turn Table Motor Driving Circuit For DC Microwave Oven |
| KR1999-56266 | 1999-12-09 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2327721A1 true CA2327721A1 (en) | 2001-06-09 |
Family
ID=19624635
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2327721 Abandoned CA2327721A1 (en) | 1999-12-09 | 2000-12-06 | Turntable motor driving circuit for a direct current microwave oven |
Country Status (5)
| Country | Link |
|---|---|
| JP (1) | JP2001196157A (en) |
| KR (1) | KR20010055165A (en) |
| CA (1) | CA2327721A1 (en) |
| DE (1) | DE10058312A1 (en) |
| FR (1) | FR2802383A1 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100454744C (en) * | 2006-07-22 | 2009-01-21 | 梁伟国 | Microwave oven |
| DE202009009826U1 (en) * | 2009-07-14 | 2009-10-08 | Kaltenbach, Agnieszka | Babykostwärmer |
| WO2011031845A1 (en) * | 2009-09-10 | 2011-03-17 | Illinois Tool Works Inc. | Appliance lock with mechanical door sensor |
| CN104676672B (en) * | 2014-06-25 | 2016-07-06 | 广东美的厨房电器制造有限公司 | Vehicle-carried microwave stove |
-
1999
- 1999-12-09 KR KR1019990056266A patent/KR20010055165A/en not_active Application Discontinuation
-
2000
- 2000-11-24 DE DE2000158312 patent/DE10058312A1/en not_active Ceased
- 2000-12-01 JP JP2000367528A patent/JP2001196157A/en active Pending
- 2000-12-06 FR FR0015791A patent/FR2802383A1/en not_active Withdrawn
- 2000-12-06 CA CA 2327721 patent/CA2327721A1/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| DE10058312A1 (en) | 2001-07-05 |
| KR20010055165A (en) | 2001-07-04 |
| FR2802383A1 (en) | 2001-06-15 |
| JP2001196157A (en) | 2001-07-19 |
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| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Dead |