JPH04369320A - Microwave oven - Google Patents

Abstract

PURPOSE:To make the setting of many programs unnecessary and carry out cooking by heating that is most suitable by determining and carrying out the output and the time of output in a plurality of stages of a high frequency wave generating device after the development of a specified change in the detection output of a gas sensor based on the time required for the detection output of the gas sensor in a heating chamber to develop the specified change. CONSTITUTION:A gas sensor 4 is positioned at the exhaust port 1a of a heating chamber 1, and the gas in it, namely the gas exhausted from the heating chamber 1, steam, for example, is detected. And in the intermediate step of rice cooking, the time of boiling is measured, and based on this boiling time it is multiplied by a constant to determine the time required for steaming, re- cooking of rice, and the time of final steaming are determined and they are actually executed. As a result, after rice boiling the output and output time of a magnetron 7 are determined in a plurality of stages, that is in three stages and the most suitable rice cooking which is cooking by heating can be made even if the amount of rice to be cooked changes.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave oven that automatically cooks food based on the output of a gas sensor.

0002

2. Description of the Related Art Conventionally, microwave ovens have been provided which cook rice using the microwave output of a magnetron, which is a high frequency generator.

That is, the output of the magnetron is temporally controlled by a microcomputer as a control means.
For example, as shown in FIG.
Stop the output (0W) for 2 hours (for example, 7 minutes), then heat at high output for T3 hours (for example, 5 minutes), then turn on the T
Heat at low power (200W) for 4 hours (for example, 5 minutes),
Then, after heating at a high power for a time T5 (for example, 1 minute), heating is performed at a low power for a time T6 (for example, 10 minutes).

0004

[Problems to be Solved by the Invention] In the conventional configuration, the times T1 to T6 are uniquely determined by the control of a microcomputer, so it is difficult to achieve good rice cooking when the amount of rice to be cooked is set in advance. Can be done.

[0005] However, since the amount of rice to be cooked varies, the optimal times T1 to T6 are naturally different depending on the amount of rice to be cooked. It becomes necessary to set and store the settings in advance.

[0006] The present invention was made in view of the above circumstances, and its purpose is to always perform optimal heating regardless of the amount, without the need to prepare a large number of programs depending on the amount for the same cooking. There is a microwave available to provide.

[0007]

[Means for Solving the Problems] The microwave oven of the present invention includes:
In a heating chamber in which high frequency waves from a high frequency generator are supplied for cooking, a gas sensor is provided to detect gas generated in the heating chamber, and the detection output of the gas sensor is set to a predetermined value under a constant output of the high frequency generator. The present invention is characterized by a configuration in which a control means is provided which measures the time required for the change to occur and, based on the measured time, determines and executes the subsequent outputs and output times of the high frequency generator in multiple stages.

[0008]

[Function] According to the microwave oven of the present invention, the output and output time of the high-frequency generator are determined in multiple stages based on the time required for a predetermined change in the detection output of the gas sensor. The output and output time of the high-frequency generator are changed in multiple stages, so that cooking is always performed optimally.

[0009]

[Example] The following is an example of the present invention shown in FIGS. 1 to 5.
This will be explained with reference to.

First, the overall schematic configuration will be described with reference to FIG. A turntable 2 is disposed within the heating chamber 1. An exhaust duct 3 is attached to the upper left side wall of the heating chamber 1 in communication with the exhaust port 1a.
A gas sensor 4 is disposed inside. In this case, the gas sensor 4 is located at the exhaust port 1a of the heating chamber 1, and detects gas within the heating chamber 1, that is, gas discharged from the heating chamber 1, such as water vapor. . The detection voltage V, which is the detection output, is set to decrease as the amount of gas to be detected, that is, the amount of water vapor increases. The detected voltage V of this gas sensor 4 is applied to an input port of a microcomputer 5 serving as a control means.

Although not shown, the operation section 6 is attached to the front surface of the main body having the heating chamber 1 inside, and is provided with a plurality of cooking menu keys, a cooking start key, and other keys. It is being The operating section 6 is configured to provide signals corresponding to pressed keys to a plurality of input ports of the microcomputer 5.

A magnetron 7, which is a high frequency generator, is disposed on the upper right side wall of the heating chamber 1, and its antenna 7
A faces into the heating chamber 1. Also, fan 8
A fan motor 8 for driving a is disposed below the magnetron 7, and its fan 8a corresponds to the air outlet 1b of the heating chamber 1.

The microcomputer 5 is connected to an AC power source 1 of 100 (V) via a magnetron relay 9.
0 to the high voltage transformer 11, and the high voltage transformer 11 is configured to provide driving power to the magnetron 7. Further, the microcomputer 5 is configured to supply an AC power source 10 to the fan motor 8 via a fan motor relay 12.

The display device 13 is configured to receive display signals from the output port of the microcomputer 5, and is configured to perform various displays.

Next, the operation of this embodiment will be explained with reference to the time chart shown in FIG. 1, the sensor output ratio characteristic diagram shown in FIG. 2, and the flowcharts shown in FIGS. 4 and 5. Here, we will show an example of rice cooking as a type of cooking.

First, a pot (made of heat-resistant crystallized glass) 14 containing rice and water is placed on the turntable 2, and the operation unit 6 is placed on the turntable 2.
Select and press the rice cooking key from the cooking menu keys,
After that, when the start key is pressed, the microcomputer 5 starts the rice cooking mode (rice cooking starts - Figure 1
time t0).

As shown in FIG. 4, the microcomputer 5 first outputs the "fan motor drive" output step S1.
By turning on the fan motor relay 12, the fan motor 8 is driven, and the fan 8a is rotated to blow air into the heating chamber 1. Then, the microcomputer 5 then selects "output high (6)".
00W)" output step S2, in which the magnetron relay 9 is turned on continuously to supply driving power to the magnetron 7 via the high voltage transformer 11, and the magnetron 7 has a strong output (600W). The oscillating operation begins to irradiate high-frequency microwaves into the heating chamber 1 through the antenna 7a, and the rice cooking operation starts.

Furthermore, the microcomputer 5
At step S3, a timer (not shown) starts operating for a preset time T1 (for example, 2 minutes). Then, the microcomputer 5 goes to the judgment step S4 of "has T1 elapsed?" Here, the microcomputer 5 judges whether or not the timer has finished counting the time T1.If the microcomputer 5 judges "NO", the judgment step S4 Repeat.

When the timer finishes counting the time T1, the microcomputer 5 determines "Y" in judgment step S4.
ES", the output step S5 is "output stop (0W)", and then the output step S6 is "fan motor stop", and the magnetron relay 9 and fan motor relay 12 are turned off, and the magnetron 7 and The fan motor 8 is stopped (time t1 in FIG. 1). Furthermore,
The microcomputer 5 enters the "T2 timer start" processing step S7, and starts a timer (not shown) to measure a preset time T2 (for example, 9 minutes).

Next, the microcomputer 5 executes “(T
2-Tx) Progress? ” is determined at step S8. In this case, the time Tx is set to, for example, 16 seconds, and therefore, the microcomputer 5 determines that
It is determined whether T2-Tx = 9 minutes - 16 seconds = 8 minutes and 44 seconds have elapsed, and if the determination is "NO", the determination step S8 is repeated. Thereafter, when the microcomputer 5 determines "YES" in this determination step S8, the microcomputer 5 goes to an output step S9 of "fan motor drive" and drives the fan motor 8 again. As a result, the gas, that is, water vapor, in the heating chamber 1 is discharged to the outside through the exhaust port 1a and the exhaust duct 3 due to the blowing action of the fan 8a, so that the so-called "cleaning" of the inside of the heating chamber 1 is performed. It is done.

The microcomputer 5 then selects "T".
2 elapsed? ” is the judgment step S10, and here it is judged whether or not the timer has finished counting the time T2. If the judgment is “NO”, the judgment step S10 is
Repeat. Thereafter, when the microcomputer 5 determines "YES" in the determination step S10 (time t2 in FIG. 1), the microcomputer 5 moves to the processing step S11 for "Vmax←V".

[0022] In this case, during the period from time t0 to time t2, a large amount of water is heated with high output to raise the temperature, and then the output is stopped to allow the rice to absorb the heated water. This corresponds to the so-called "beginning trickle" at the beginning of the rice cooking operation.

[0023] Then, the microcomputer 5
max←V" processing step S11, the detected voltage V of the gas sensor 4 at that time is stored in a RAM (not shown) as the maximum value Vmax. After that, the microcomputer 5 goes to the output step S12 of "strong output (600W)", drives the magnetron 7 to a constant high output, and then moves to the processing step S13 of "Tα count start". .

In processing step S13, the microcomputer 5 causes a counter (not shown) to start counting to measure the time Tα after time t2. Then, the microcomputer 5 calculates “V>Vmax
? ”, and here it is determined whether the detected voltage V of the gas sensor 4 is greater than the maximum value Vmax stored in the RAM, and if “YES” is determined.
” (V>Vmax), when it is determined that “Vmax ←
The process proceeds to step S15, where the detected voltage V of the gas sensor 4 is rewritten and stored in the RAM as the maximum value Vmax, and the process returns to determination step S14. After that, the microcomputer 5 performs judgment step S14.
When it is determined “NO” (V≦Vmax), “V
min=(1-α)×Vmax” processing step S
It becomes 16.

The constant α is obtained through experiments, and is set to α=0.1, for example, and is stored in advance in a ROM (not shown).

Therefore, in processing step S16, the microcomputer 5 calculates Vmin=(1-α)×Vmax
=(1-0.1)×Vmax
=0.9×Vmax
...(
1) is performed to determine the minimum value Vmin, and this is stored in the RAM. Then, the microcomputer 5 goes to step S17 to determine "V<Vmin", and here, the detected voltage V of the gas sensor 4 is the minimum value Vm.
This is to judge whether or not it is smaller than in, and “NO” (V
≧Vmin), the determination step S17 is repeated.

When the microcomputer 5 determines "YES"(V<Vmin) in the determination step S17 (time t3 in FIG. 1), it proceeds to the next "Tα memory" processing step S18, and stores the counter at that time. The count value, ie, the elapsed time Tα from time t2, is read and stored in the RAM. That is, the elapsed time T which is this measurement time
α is the time required for the detection voltage V of the gas sensor 4 to exhibit a predetermined change under a constant output, that is, under a strong output, that is, to become smaller than the minimum value Vmin.

Note that the detection voltage V of the gas sensor 4 is the minimum value V
The time when the rice becomes smaller than min (time t3 in FIG. 1) is set to be the time when the rice is cooked, and therefore, the period from time t2 to time t3 is the so-called "middle time" during the rice cooking operation. It is equivalent to "Pappa".

The microcomputer 5 then proceeds to output step S19 of "low output (200W)", in which the magnetron relay 9 is turned on and off at a predetermined duty ratio set in advance, and the magnetron 7 is turned on and off at a predetermined duty ratio. The output is controlled to be low (for example, 200W). Furthermore,
The microcomputer 5 moves to processing step S20 of "Tβ=β×Tα". In this case, the constant β is obtained through experiments, and is set to β=1.0, for example, and is stored in the ROM in advance.

Therefore, in processing step S20, the microcomputer 5 calculates Tβ=β×Tα=1.0×Tα=Tα
. . . As shown in (2), the time Tβ is calculated and stored in the RAM, and a counter (not shown) starts counting the time Tβ.

After that, the microcomputer 5 executes "
Tβ finished? ” is the judgment step S21, and here,
It is determined whether or not the counter has finished counting the time Tβ, and if the determination is "NO", the determination step S21 is repeated. Thereafter, when the microcomputer 5 determines "YES" in the determination step S21, the microcomputer 5 (
At time t4 in FIG. 1), the process moves to output step S22 of "high output (600W)".

[0032]The period from time t3 to time t4 is as follows:
This corresponds to the so-called ``murasashi'' method in which rice is heated over low heat after it is cooked during the rice cooking operation.

In the output step S22, the microcomputer 5 continuously turns on the magnetron relay 9 to drive the magnetron 7 at a high output (600 W). Further, the microcomputer 5 goes to processing step S23 of "T.gamma.=.gamma.xT.alpha." and calculates the time T.gamma. In this case, the constant γ is obtained experimentally, for example γ=
This is set to 0.2 and is stored in the ROM in advance.

Therefore, in this processing step S23, the microcomputer 5 calculates Tγ=γ×Tα=0.2×Tα (
3), the time Tγ is calculated and stored in the RAM, and the counter starts counting the time Tγ.

[0035] Next, the microcomputer 5
end? ” is the judgment step S24, and here it is judged whether the counter has finished counting operation of the time Tγ.
Repeat step 24. Thereafter, when the microcomputer 5 determines "YES" in the determination step S24 (see FIG.
At time t5), the process moves to output step S25 of "low output (200W)".

Note that the period from time t4 to time t5 is as follows:
This corresponds to the so-called "double cooking" in which rice is temporarily heated over high heat during the rice cooking operation.

[0037] In the output step S25, the microcomputer 5 drives the magnetron 7 at a low output (200 W) as in the output step S9. Furthermore, the microcomputer 5 performs the processing step S26 of "Tδ=δ×Tα".
Then, the time Tδ is calculated. In this case, the constant δ
is obtained through experiments, and is set to, for example, δ=2.0, which is stored in advance in the ROM.

Therefore, in this processing step S26, the microcomputer 5 calculates Tδ=δ×Tα=2.0×Tα (
As shown in step 4), the time Tδ is calculated and stored in the RAM, and the counter starts counting the time Tδ.

The microcomputer 5 next selects "Tδ
end? ” is the judgment step S27, and here it is judged whether or not the counter has finished counting the time Tδ. If the judgment is “NO”, the judgment step S27 is
Repeat step 27. Thereafter, when the microcomputer 5 determines "YES" in the determination step S27 (see FIG.
At time t6), the process moves to output step S28 of "end of rice cooking".

[0040] Furthermore, the period from time t5 to time t6 is as follows:
This corresponds to the so-called "finishing unevenness" in which rice is cooked twice and then heated over low heat.

[0041] Then, in output step S28 of "end of rice cooking", the microcomputer 5 turns off both the magnetron relay 9 and the fan motor relay 12, thereby ending the rice cooking mode.

As described above, according to this embodiment, the boiling time Tα called "middle pappa" during the rice cooking operation is measured, and based on this boiling time (measurement time) Tα, the constant β, γ
and δ are multiplied to determine and execute the varnishing time Tβ, double cooking time Tγ, and final varnishing time Tδ, so after boiling, the output and output time of the magnetron 7 are determined in three stages of multiple stages. Now, even if the amount of rice to be cooked differs, the rice can always be cooked at the optimum level. Therefore, unlike the conventional method, a large number of programs can be set in the microcomputer 5 according to the amount of rice to be cooked. There is no need to remember it.

Furthermore, if a large number of programs are set according to the amount of rice to be cooked for the same cooking as in the past, a key selection operation is required to select the program, which makes the operation difficult. Although it is extremely troublesome, in this embodiment, the rice cooking operation is always optimally controlled by simply selecting and operating the rice cooking key, regardless of the amount of rice cooked, so the operability is significantly improved.

Moreover, when the power demand is large, such as in the evening, the power supply voltage fluctuates, that is, the power supply voltage
Rice cooking is often performed when the amount of rice has decreased by about 0%, but in such cases, with conventional time control methods, errors occur even if a program is selected and set according to the amount of rice cooked. However, in this embodiment, the subsequent rice cooking operation is determined based on the boiling time Tα in a state where the power supply voltage is reduced, so that the conventional problem can be solved.

Note that the present invention is not limited to the embodiments described above and shown in the drawings; for example, the constants α, β,
It goes without saying that γ and δ can be set as appropriate depending on the desired rice cooking mode, and that modifications can be made as appropriate without departing from the spirit of the invention.

[0046]

Effects of the Invention As described above, the microwave oven of the present invention is capable of controlling the subsequent multiple stages of the high frequency generator based on the time required for the detection output of the gas sensor that detects the gas generated in the heating chamber to exhibit a predetermined change. Since the output and output time are determined and executed, there is no need to set multiple programs depending on the amount of food to be cooked, and the excellent effect is that the optimal heating cooking can be performed at all times. It is something to play.

[Brief explanation of drawings]

FIG. 1: A time chart for explaining the operation of an embodiment of the present invention.

[Figure 2] Sensor output ratio characteristic diagram for explaining the action

[Figure 3] Overall schematic configuration diagram

[Figure 4] Flowchart for explaining the action part 1

[Figure 5] Flowchart part 2

[Figure 6] A diagram equivalent to Figure 1 showing a conventional example

[Explanation of symbols] In the figure, 1 is a heating chamber, 3 is an exhaust duct, 4 is a gas sensor,
5 is a microcomputer (control means), 7 is a magnetron (high frequency generator), 8 is a fan motor, and 8a is a fan.

Claims (1)

[Claims] 1. A device for heating and cooking by supplying high-frequency waves from a high-frequency generator into a heating chamber, comprising: a gas sensor for detecting gas generated in the heating chamber; and a sensor for detecting gas under a constant output of the high-frequency generator. A microwave oven comprising: a control means for measuring the time required for the output to exhibit a predetermined change, and determining and executing subsequent outputs and output times of a plurality of stages of a high frequency generator based on the measured time.