JP2003074868A - Microwave oven - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a microwave oven, in which heating power for a to-be- cooked material can be finely regulated. SOLUTION: A magnetron 10 is connected through a drive-control circuit 25 to a control circuit 56, and a turn-table motor 5, a cooling fan motor 12, a heating-fan motor 17 and a heater 19 are connected through a driving circuit 51 to the control circuit 56. Further, a temperature sensor 14, a weight sensor 59, a display 22, and an input circuit 58 are connected to the control circuit 56. A number in an automatic cooking menu is set by operating a menu-item setting button. on a control panel, and a start switch is turned on, then operation for the automatic cooking menu is started. If a user turns an output-regulation knob on the control panel before starting a cooking or during a cooking, an output of the magnetron 10, which is set beforehand in accordance with the automatic cooking menu is changed to an optional output, and in accordance therewith the control circuit 56 controls the magnetron 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave oven with improved magnetron output control.

[0002]

The conventional microwave oven is
An inverter circuit is provided in the drive power source of the magnetron to change the output of the magnetron from low output (for example, 100 W) to high output (for example, 800 W). The output of such a magnetron can be switched based on the program of the automatic cooking menu or according to the operation of the output switching key on the operation panel.

However, in the conventional microwave oven, the output of the magnetron which can be switched by the output switching key is, for example, 10.
It was set stepwise such as 0W, 200W, 500W, 600W, 800W. For this reason, the heating state of the object to be heated cannot be finely adjusted. For example, if the output of the magnetron is 200 W and the heating intensity is too weak to boil the object to be heated, the heating intensity will be too high if switched to 500 W. There were problems such as spilling and boiling down.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a microwave oven capable of finely adjusting the heating state of an object to be heated.

[0005]

A microwave oven according to claim 1 of the present invention comprises a magnetron for heating an object to be heated by irradiating a heating chamber with microwaves, a magnetron drive circuit for driving the magnetron, and a rotating circuit. Output setting means movably provided for setting the output of the magnetron to an arbitrary value from the minimum output to the maximum output, and control means for controlling the output of the magnetron based on the turning operation of the output setting means. And is provided. According to the above configuration, the output of the magnetron can be set to an arbitrary output according to the rotation amount of the output setting means, so that the object to be heated can be cooked in the optimum state.

The microwave oven according to claim 2 of the present invention is
A magnetron that heats an object to be heated by irradiating a heating chamber with a microwave, and a magnetron drive circuit that drives the magnetron, and is operably provided, and the output of the magnetron is any value from the minimum output to the maximum output. Output setting means for setting, the heated object setting means for setting the type of the heated object, and controlling the output of the magnetron based on the operation of the output setting means, depending on the type of the heated object And a control means capable of executing automatic cooking for driving the magnetron with the output, wherein the control means is configured to change the output of the magnetron based on the operation of the output setting means during execution of the automatic cooking. It is characterized by

Normally, the output of the magnetron at the time of execution of automatic cooking is set on the premise that cooking is performed in a state where all the predetermined ingredients are contained in a predetermined container. Therefore, when the automatic cooking is performed using a container different from the predetermined container, or when the automatic cooking is performed by slightly changing the ingredients, a good cooking state may not be obtained.
According to the above configuration, even when the automatic cooking is executed under the condition different from the designated condition, the output of the magnetron can be appropriately changed while observing the cooking state of the object to be heated.

In this case, it is preferable that the maximum output or the minimum output of the magnetron is set for each kind of the object to be heated (inventions of claims 3 and 4). There is an appropriate heating state for each type of object to be heated, and if the output of the magnetron is set to deviate from this state, the object to be heated cannot be cooked well. According to the above-mentioned composition, it can prevent that the output of a magnetron is made too high or too low and cooking is failed.

Further, a heater for heating an object to be heated in the heating chamber and a heater drive circuit for driving the heater are provided.
When the control means is configured to be capable of performing mixed cooking in which the heater and the magnetron are simultaneously driven to heat and cook the object to be heated, the output of the magnetron which can be set by the output setting means at the time of performing the mixed cooking is It is advisable to limit the power consumption of the magnetron so that it is below a predetermined capacity (the invention of claim 5).

According to the above construction, it is possible to avoid the trouble that the output of the magnetron is excessively increased and the electric power used exceeds the maximum electric power amount, and the breaker is broken or the fuse is blown.

Further, display means for displaying the output of the magnetron may be provided (the invention of claim 6). According to the above configuration, the output of the magnetron set by the output setting means can be visually recognized.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment in which the present invention is applied to a microwave oven with a heater will be described below with reference to the drawings. First, FIG. 1 is a front view of a microwave oven according to this embodiment, and FIG. 2 is a schematic cross-sectional top view of the microwave oven. In these figures, a heating chamber 2 having an open front is arranged inside a cabinet 1. A door 3 that opens and closes the front opening of the heating chamber 2 is rotatably attached to the front surface of the cabinet 1. The heating chamber 2
A turntable 4 is provided at the bottom of the. The turntable 4 is a turntable motor 5 (only shown in FIG. 3) disposed below the bottom of the heating chamber 2.
It is configured to be rotated by.

On the left and right side walls of the heating chamber 2, there are provided support portions 6 for supporting a rectangular plate (not shown) in two steps, upper and lower. At the time of heating and cooking, food to be heated is placed on the turntable 4 or the square plate. In addition, an excitation port 7 is provided on the right side wall of the heating chamber 2.
Is provided.

The heating chamber 2 in the cabinet 1
A machine room 8 is provided on the right side of. A waveguide 9 and a magnetron 10 are arranged in the machine room 8.
One end of the waveguide 9 is fixed to the peripheral edge of the excitation port 7, and the magnetron 10 is fixed to the other end. Thereby, the microwave radiated from the magnetron 10 is supplied into the heating chamber 2 via the waveguide 9 and the excitation port 7.

A cooling fan device 11 is arranged at the rear of the machine room 8. The cooling fan device 11 includes a cooling fan motor 12 and a fan 13 fixed to a rotation shaft of the motor 12. Also, the machine room 8
A non-contact type infrared temperature sensor 14 is provided in a portion located in the upper part of the right rear portion of the heating chamber 2 inside. The temperature sensor 14 includes a plurality of infrared detection elements (thermopile) that are not shown and are arranged linearly. The detection field of view of the temperature sensor 14 crosses the turntable 4 in the heating chamber 2 in the diameter direction.
Therefore, when the turntable 4 makes one revolution, the surface temperature of the entire area on the turntable 4, that is, the surface temperature of the object to be heated on the turntable 4 can be detected by the temperature sensor 14.

On the other hand, a hot air fan device 15 is provided at the rear of the heating chamber 2. The hot air fan device 15
Is a fan casing 16 integrally provided in the rear part of the rear wall of the heating chamber 2, a hot air fan motor 17 arranged in the rear part of the fan casing 16, and the fan casing of the rotary shafts of the hot air fan motor 17. The hot-air fan 18 is fixed to a portion projecting inside the heater 16, and the heater 19 is arranged in the fan casing 16 around the hot-air fan 18.

An intake port 20a consisting of a large number of holes is provided in a portion of the rear wall of the heating chamber 2 which is located approximately in the center and in front of the hot air fan 18. In addition, in the upper and lower parts of the rear wall of the heating chamber 2, a discharge port 20 including a large number of holes is formed.
b is provided. With the above configuration, the heater 19
Is energized and the hot air fan motor 17 is driven to rotate, the air in the heating chamber 2 is sucked into the fan casing 16 through the intake port 20a, and the air in the fan casing 16 heated by the heater 19 is It is discharged into the heating chamber 2 through the discharge port 20b.

An operation panel 21 is arranged at the right end in FIG. 1 on the front surface of the cabinet 1. As shown in FIG. 4, a display unit 22 (corresponding to a display unit) made of, for example, a liquid crystal display is provided on the upper portion of the operation panel 21, and a start switch 23a and a predetermined automatic cooking menu type are provided on the lower portion thereof. Auto menu switch 23b for setting the, automatic cooking menu number, setting knob 23c for setting the temperature and cooking time of manual cooking,
Various setting switches 23d relating to manual cooking, a cancel switch 23e, an output adjusting knob 23f (corresponding to output setting means) for setting the output of the magnetron 10, and the like are provided. When the start switch 23a is operated after the automatic cooking menu is set by the automatic menu switch 23b or the setting knob 23c, the automatic cooking menu, that is, the automatic cooking according to the type of the object to be heated is executed. Therefore, in this embodiment, the auto menu switch 23b and the setting knob 23c function as a heated object setting means.

Now, FIG. 3 shows an electric circuit diagram of the microwave oven according to the present embodiment. This drawing mainly shows the drive control circuit 25 of the magnetron 10 connected to the AC power supply 24. Specifically, the input terminals of a full-wave rectifier circuit 27 composed of a diode bridge are connected to both ends of the AC power supply 24 via capacitors 26. One of the output terminals of the full-wave rectifier circuit 27 is connected to one end of the smoothing capacitor 29 via the choke coil 28, and the other of the output terminals is connected to the other end of the smoothing capacitor 29. A DC power supply circuit 30 is composed of the capacitor 26, the full-wave rectifier circuit 27, the choke coil 28, and the smoothing capacitor 29.

DC power supply line 3 of the DC power supply circuit 30
An inverter circuit 31 is connected to 0a and 30b. The inverter circuit 31 is configured as follows. That is, switching elements 32 and 33 made of, for example, IGBTs are connected in series between the DC power supply lines 30a and 30b, and freewheel diodes 34 and 35 are connected in antiparallel to the switching elements 32 and 33, respectively. . In addition, the DC power supply lines 30a, 3
Capacitors 36 and 37 are connected in series between 0b.

The common connection terminal of the switching elements 32 and 33 is connected to one terminal of the primary coil 38a of the high frequency transformer 38, and the resistor 39 and the capacitor 40 are connected to the emitter of the switching element 33 of the lower arm.
Connected through. Also, the capacitor 36,
The common connection point of 37 is the primary coil 3 of the high frequency transformer 38.
8a is connected to the other terminal.

A secondary coil 38b and a filament coil 38c are provided on the secondary side of the high frequency transformer 38. A magnetron drive circuit 41 is connected to the secondary coil 38b. Magnetron drive circuit 41
Is two diodes 42, 43, two capacitors 4
It is composed of a voltage doubler circuit composed of four resistors 45, 45 and two resistors 46, 47, and applies a high voltage to the magnetron 10.

A filament circuit 48 is connected to the filament coil 38c. Filament circuit 48
Includes diodes 49 and 50 which are Schottky barrier diodes, a capacitor 51 which is a smoothing capacitance element, and a filter circuit 55 which includes coils 52 and 53 and capacitors 54a and 54b. One end of the filament coil 38c is connected to one terminal of the cathode of the magnetron 10 via the diode 49 and the coil 52.
The other end of is connected to the other terminal of the cathode of the magnetron 10 via the coil 53. The cathode of the diode 50 is connected to the cathode of the diode 49, and the anode of the diode 50 is connected to the filament coil 38.
It is connected to the other end of c. That is, the diode 49,
50 is connected in parallel and in series with the filament coil 38c, and the capacitor 51 is connected in parallel with the diode 50.

The switching elements 32 and 33 of the inverter circuit 31 are on / off controlled by a control circuit 56 as a control means at a high frequency duty ratio to pass an alternating current current through the primary coil 38a, and the secondary coil 38b and the filament coil 38c. Induce a high frequency current in the. The current induced in the filament circuit 48 is the diode 4
It is rectified by 9, 50 and supplied to the cathode of the magnetron 10. As a result, the magnetron 10 is brought into a state where it is easy to emit electrons. The high frequency current induced in the secondary coil 38b is increased in voltage by the magnetron drive circuit 41 and applied to the magnetron 10, whereby the magnetron 10
Oscillates.

A drive circuit 57 (corresponding to a heater drive circuit) for the turntable motor 5, the cooling fan motor 12, the hot air fan motor 17, and the heater 19 is connected to the control circuit 56. An AC power source is supplied to the drive circuit 57. In addition, the control circuit 5
An input circuit 58 including various switches and knobs of the operation panel 21, the display 22, the temperature sensor 14, and a weight sensor 59 are connected to the control unit 6. The weight sensor 59 detects the weight of the object to be heated on the turntable 4.

The control circuit 56 includes a microcomputer, and linearly changes the ON times of the switching elements 32 and 33 of the inverter circuit 31 to continuously output the magnetron 10 from the minimum output to the maximum output. It is supposed to be changed. In particular, in this embodiment, the filament circuit 48 includes a magnetron 1
Since diodes 43 and 44, which are rectifying means for rectifying the current flowing through the cathode of 0, are provided, stable continuous oscillation is possible even in the low output region. The detailed configuration of the drive control circuit 25 is disclosed in the unpublished Japanese Patent Application No. 2001-62219 previously filed by the present applicant.

The control circuit 56 controls the output of the magnetron 10 based on a control program stored in the ROM of the microcomputer, and outputs the magnetron 10 based on the turning operation of the output adjusting knob 23f. Is changed to any value from the lowest output to the highest output. At this time, in the ROM of the microcomputer of the control circuit 56, the magnetron 1 for each automatic cooking menu, that is, for each type of object to be heated.
The settable range of the output of 0, in other words, the settable minimum output and maximum output of the magnetron 10 is stored, and the variable range of the magnetron 10 based on the turning operation of the output adjusting knob 23f is limited. ing.

Next, the operation of this embodiment will be described with reference to FIG. FIG. 5 is a flow chart showing a process from the start to the end of cooking (hereinafter referred to as range cooking) using the magnetron 10. First, various switches and knobs on the operation panel 21 are operated to set the range cooking (step S).
1).

For example, in the case of manual cooking, after operating the setting switch 23d, the setting knob 23c is operated to set the cooking time and the output adjusting knob 23f is operated to set the output of the magnetron 10. In the present embodiment, the output of the magnetron 10 by the output adjusting knob 23f can be set to any value from 0 W to 800 W, for example. Set cooking time and magnetron 10
The output of each is displayed on the display 22. On the other hand, in the case of the automatic cooking menu, the automatic menu key 23b or the setting knob 23c is operated to set the automatic cooking menu.

Succeedingly, in a step S2, it is determined whether or not an automatic cooking menu is set. When the manual cooking is set (NO), the start switch 2
The magnetron 10 is driven so that the output is set based on the operation of 3a, and cooking is started (YES in step S3). In the next step S4, it is determined whether or not the output adjusting knob 23f has been operated, and if operated (NO), the output of the magnetron 10 is changed according to the rotation amount and the rotating direction of the output adjusting knob 23f. (Step S5). That is, the output of the magnetron 10 can be changed to an arbitrary value even during cooking. When the set time is reached (YES in step S6)
Stops driving the magnetron 10 and finishes cooking,
When the set time has not been reached (NO in step S6)
To return to step S4.

On the other hand, when the automatic cooking menu is set (YES in step S2), the process proceeds to step S7. In step S7, the settable range of the output of the magnetron 10 according to the automatic cooking menu is set. For example, in the case of the automatic cooking menu "chawanmushi",
The settable range is set to 100W to 300W. Further, in the case of the automatic cooking menu "jam", the cooking process is composed of the first and second processes having different heating patterns, and the settable range of the second process is set to 50W to 200W. Further, in the case of "boiled gomeme", the cooking process is composed of the first to third processes having different heating patterns, and the settable range of the second process is 100W-
In 200W, the setting range of the third stroke is 50W-100
It is set to W.

In the case of the automatic cooking menu "curry and stew stew" in which the mixed cooking is simultaneously driven by driving the magnetron 10 and the heater 19, the settable range of the magnetron 10 is set according to the output of the heater 19. It This is the output of the heater 19 and the magnetron 10
This is because, if the total output of the above exceeds the predetermined value, the electric power used by the entire microwave oven exceeds the maximum capacity and the fuse blows.
Therefore, if the output of the heater 19 changes during cooking,
Along with this, the settable range of the magnetron 10 also changes. The settable range of the magnetron 10 in this case is set in consideration of the power consumption of electric parts such as an interior light (not shown), the cooling fan motor 12, the hot air fan motor 17, and the like included in the microwave oven.

When the start switch 23a is operated to start cooking (step S8), first, the weight sensor 59 detects the weight of the object to be heated (step S9). Further, the temperature sensor 14 detects the temperature distribution of the object to be heated and calculates the average temperature of the object to be heated based on the temperature distribution (step S10). Then, based on the set control program of the automatic cooking menu, the output of the magnetron 10 is controlled so that the output value is in accordance with the gravity and the average temperature of the object to be heated, and the cooking is executed (step S11). At this time, the display 22 displays the average temperature and temperature distribution of the object to be heated and the output of the magnetron 10.

In the next step S12, it is determined whether or not the output adjusting knob 23f has been operated. When the output adjustment knob 23f is operated (NO), it is determined whether or not the output of the magnetron 10 set according to the rotation amount and the rotation direction of the output adjustment knob 23f is within the settable range. (Step S13). Then, if it is within the settable range (YES), the output of the magnetron 10 is changed according to the rotation amount and the rotation direction of the output adjustment knob 23f (step S14).

On the other hand, if it is out of the settable range (NO in step S13), the output adjusting knob 23f
Regardless of the amount of rotation of the magnet, the output setting value is limited and the output of the magnetron 10 is changed to the highest value (upper limit value) or the lowest value (lower limit value) of the settable range (steps S15, S1).
4). Therefore, the output of the magnetron 10 will not be changed to an output outside the settable range. When the cooking end condition (for example, the average temperature of the objects to be heated reaches the heating end temperature) is satisfied (Y in step S16).
ES), the driving of the magnetron 10 is stopped and the cooking is finished.

According to this embodiment, since the output of the magnetron 10 can be set to an arbitrary value by rotating the output adjusting knob 23f, it is possible to cook the object to be heated with the optimum heating output.

In this case, the output of the magnetron 10 can be changed based on the turning operation of the output adjusting knob 23f even during range cooking. Therefore, it is possible to change to an appropriate output while observing the cooking state of the object to be heated.

By the way, the output of the magnetron 10 of the automatic cooking menu is set on the assumption that cooking is performed in a state where a predetermined container and all predetermined materials are contained in the predetermined container. Therefore, if the user changes the material slightly or uses a container with a shape or material different from the predetermined container, the boiling state is too strong and spills or collapses occur, or until boiling It takes too much time to obtain a good cooking state, and cooking may fail. On the other hand, in the present embodiment, even when the automatic cooking is executed under the condition different from the designated condition, the output of the magnetron 10 can be adjusted while watching the cooking state of the object to be heated. Goods can be finished.

In this embodiment, the settable range of the magnetron 10 is set for each automatic cooking menu. Therefore, it is possible to prevent the user from mistakenly setting the output of the magnetron 10 that causes the set automatic cooking menu to deviate from the appropriate heating state and failing to cook. Specifically, in the case of the automatic cooking menu "chawanmushi" that produces "su" when the heating intensity is too strong and the automatic cooking menu "jam" that spills or burns, the user mistakenly outputs the magnetron 10. It is possible to prevent cooking from failing by setting to a high output.

Further, in this embodiment, in the case of mixed cooking in which the magnetron 10 and the heater 19 are driven simultaneously, the settable range of the output of the magnetron 10 is set according to the output of the heater 19. As a result, it is possible to prevent the electric power used by the microwave oven from exceeding the maximum capacity and causing the fuse to blow or the breaker to fall.

Furthermore, since the output of the magnetron 10 is displayed on the display 22, it is possible to visually recognize the current output setting state of the magnetron 10.

The present invention is not limited to the embodiments described above and shown in the drawings, but the following modifications and expansions are possible. Even when the automatic cooking menu is executed, the output of the magnetron 10 (the output of the magnetron 10 at the start of cooking) may be changed by the output adjusting knob 23f before the heating is started. In this case, when the automatic cooking menu is set, the magnetron 10 at the start of cooking
The output of the magnetron 10 may be appropriately changed by observing the display.

The output setting means is not limited to the structure that can be rotated, but for example, a push-operable switch for increasing the output and a pushable switch for decreasing the output are provided, and depending on the pressing time of these switches. Alternatively, the output of the magnetron may be continuously changed.

Only the minimum output or maximum output of the magnetron that can be set for each type of object to be heated may be set. This is because, depending on the type of object to be heated, a problem may occur due to an excessive increase in the output of the magnetron, or a problem may occur due to an excessive decrease in the output of the magnetron.

[0045]

As is apparent from the above description, in the microwave oven according to the first aspect of the present invention, the output of the magnetron is set to an arbitrary value from the minimum output to the maximum output by rotating the output setting means. Since it can be set, it is possible to cook the object to be heated in an optimum state, and it is possible to prevent the cooking from failing due to spillage or collapse.

The microwave oven according to claim 2 of the present invention is
In the configuration that can perform automatic cooking that drives the magnetron with the output according to the type of the object to be heated, the output of the magnetron can be changed based on the operation of the output setting means during the execution of the automatic cooking. Even when the automatic cooking is performed under a condition different from the condition, the output of the magnetron can be appropriately changed while observing the cooking state of the object to be heated, and the object to be heated can be excellently finished.

[Brief description of drawings]

FIG. 1 is a front view showing a microwave oven according to an embodiment of the present invention in a perspective view.

FIG. 2 is a diagram schematically showing an internal structure of a microwave oven.

FIG. 3 is an electric circuit diagram of a microwave oven.

FIG. 4 is a front view of an operation panel

FIG. 5 is a flowchart showing an output setting process of the magnetron during execution of range cooking.

[Explanation of symbols]

In the figure, 2 is a heating chamber, 10 is a magnetron, 19 is a heater, 22 is an indicator (display means), 23b is an auto menu switch (heated object setting means), 23c is a menu setting knob (heated object setting means), 23f is an output adjusting knob (output setting means), 41 is a magnetron drive circuit, 56
Is a control circuit (control means), and 57 is a drive circuit (heater drive circuit).

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Claims (6)

[Claims] 1. A heating chamber that accommodates an object to be heated therein, a magnetron that heats the object to be heated by irradiating the heating chamber with microwaves, and a magnetron drive circuit that drives the magnetron. Output setting means operably provided for setting the output of the magnetron to an arbitrary value from the minimum output to the maximum output, and a control means for controlling the output of the magnetron based on the rotating operation of the output setting means. And a microwave oven. 2. A heating chamber that accommodates an object to be heated therein; a magnetron that heats the object to be heated by irradiating the heating chamber with microwaves; and a magnetron drive circuit that drives the magnetron. And an output setting means for setting the output of the magnetron to an arbitrary value from the minimum output to the maximum output, a heated object setting means for setting the type of the heated object, and an operation of the output setting means. While controlling the output of the magnetron based on the, and a control means capable of executing automatic cooking to drive the magnetron with an output according to the type of the object to be heated, the control means, during execution of automatic cooking A microwave oven, wherein the output of the magnetron can be changed based on an operation of the output setting means. 3. The microwave oven according to claim 1, wherein the maximum output of the magnetron is set for each type of object to be heated. 4. The microwave oven according to claim 1, wherein a minimum output of the magnetron is set for each type of the object to be heated. 5. A heater for heating an object to be heated in a heating chamber, and a heater drive circuit for driving the heater, wherein the control means drives the heater and the magnetron simultaneously to heat and cook the object to be heated. It is configured such that mixed cooking can be performed, and the output of the magnetron that can be set by the output setting means when the mixed cooking is performed is limited so that the electric power used by the heater and the magnetron is equal to or less than a predetermined capacity. The microwave oven according to any one of claims 1 to 4. 6. The microwave oven according to claim 1, further comprising display means for displaying the output of the magnetron.