JPH0239693B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION The present invention relates to a heating device, and more particularly to a heating device that performs automatic heating using a plurality of sensors.

Conventional configuration and its problems Conventionally, in heating devices capable of automatic cooking,
Various sensor means have been used to detect the progress of heating of an object to be heated. For example, in a microwave oven, a thermistor is used to measure the exhaust temperature, a humidity sensor is used to detect steam generated from food, a gas sensor is used to detect steam and gas generated from food, and an infrared sensor is used to detect steam generated from food. A wide variety of sensors have been proposed and commercialized, including those that measure the surface temperature of food using a sensor, and those that measure the internal temperature of food using a temperature probe.

Among these, humidity sensors and gas sensors that detect food vapor have excellent detection reproducibility during cooking that raises the temperature of food to 70 to 100 degrees Celsius.
You can expect stable performance. It is also less susceptible to the effects of the food placement position and power supply voltage, and operates stably even in relatively high-temperature environments. The control circuit is also simple, reliable, and inexpensive.

On the other hand, the detection time will be different depending on whether the food is covered with a wrap or lid or not. FIG. 4 is a graph showing such a state, and shows how steam is generated from the food. If there is a wrap, the steam will remain within the wrap at the beginning of heating and will not blow out into the heating chamber. As the pressure inside the wrap gradually increases, the steam finally displaces the wrap at point A and blows out into the heating chamber. This is the detection point, and the detection time at this time is T ₁
It is. However, if there is no wrap, the steam will gradually blow out into the heating chamber from the beginning of heating, and eventually reach a certain threshold at point B. The detection time T ₁ ' at this time is shorter than the detection time T ₁ when there is a lap. In other words, if there is no lap, it will break early.

Generally, in automatic cooking using sensors, a method called K value control is adopted. This is the detection time T ₁
After the elapse of time, additional heat is applied for a certain period of time, and the additional heating time is determined by multiplying the detection time _T1 by a constant K for each menu. Therefore, by adjusting the constant K, the total heating time can be optimized. However, as shown in FIG. 4, if the detection times are different even though the amount is the same, it is not possible to finish both with and without lapping in the optimal time.

In this way, humidity sensors and gas sensors
Stable operation is possible under various condition changes, but
At this time, it was necessary to limit the presence or absence of wraps or lids depending on the menu.

On the other hand, a multi-sensor method has already been proposed that uses a combination of sensors each having advantages and disadvantages. For example, Japanese Unexamined Patent Publication No. 126294/1984 discloses a control system that combines a gas sensor and a temperature sensor. This automatically cooks food by switching sensors depending on the menu.For example, a sake can uses a gas sensor to detect alcohol.
For reheating, a temperature sensor detects the temperature of the exhaust gas in the heating chamber, and for grilling, the gas generated from burnt food is detected. According to this invention, it is not possible to eliminate the variation in finished product due to the presence or absence of a wrap or lid as described above.

OBJECTS OF THE INVENTION The present invention eliminates the above-mentioned conventional drawbacks, and aims to provide a heating device that can perform optimal heating regardless of the presence or absence of a wrap or lid.

Structure of the Invention In order to achieve the above object, the heating device of the present invention combines a humidity sensor or a gas sensor that can be expected to operate stably under various condition changes, and a temperature sensor that is not easily affected by the presence or absence of lapping. First, the weight of the object to be heated is detected by a weight sensor, or a certain time T _{s is calculated based on the weight input by a weight input means, and the time T s} is calculated depending on whether the detection by the gas or humidity sensor is earlier or later than this time. If there are no laps, it is controlled by a temperature sensor. If there are laps, a humidity sensor or gas sensor is used to achieve a stable finish, and if there are no laps, a temperature sensor is used to prevent premature breakage. This has the effect of

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view of the main body of the heating device according to the present invention. A door body 2 is provided on the front of the main body 1 so that it can be opened and closed freely.
is pivoted. And on the operation panel 3,
A menu key 4 for selecting a cooking menu is provided.

FIG. 2 is a detailed view of the operation panel 3. As shown in FIG.
The user selects a desired menu using the menu key 4. For example, press "cold rice" for reheating. Then, "R1" appears in the upper two digits of the four-line numeric display on the display window 5, indicating that the chilled rice has been decoded by the control unit and has been validly input. Subsequently, when the start button 6 is pressed, automatic cooking is started.

In addition, a mode setting key 7 for manual cooking, a timer knob 8, and a temperature setting key 9 are arranged on the operation panel 3. Reference numeral 10 is a cancel key for canceling a preset menu or heating pattern and stopping cooking in progress.

Now, FIG. 3 is a block diagram showing the construction of such a heating device. Various commands input from the operation panel 3 are decoded by the control section 11.
Based on this command, the control unit 11 displays a predetermined display and further controls the progress of heating.

An object to be heated 13 is placed in the heating chamber 12 and heated by a magnetron 14 and an electric heater 15 serving as heating means. The magnetron 14 is energized and controlled by the controller 11 via the driver 16 . The blower 17 cools the magnetron 14 and ventilates the inside of the heating chamber 12. Reference numeral 18 denotes an exhaust guide that sends the exhaust gas out of the aircraft.
Inside the exhaust guide 18, there are a gas sensor 19 that can detect humidity and a temperature sensor 2 that can detect exhaust temperature.
0 is provided, and the controller 11 passes through the detection circuit 21.
The progress of heating is communicated to the operator. Based on the information of these sensors, the control unit 11 performs a lap determination, which will be described later, and selects the sensor to be used.

22 is a mounting table for the object to be heated 13, and 23 is a weight detection sensor means. A strain gauge or the like is used as the sensor, and weight information is input to the control section 11.

Now, as already described, the way steam is generated from food differs depending on whether there is a wrap or not, as shown in FIG. Therefore, in the present invention,
The presence or absence of lapping is determined by the method shown in FIG. 5 or 6, and a sensor is selected so that optimal heating can be performed regardless of the presence or absence of lapping.

First, the lap discrimination method shown in FIG. 5 will be explained.
This is a weight function “T _s (w)” from the start of heating.
The presence or absence of a lap is determined based on whether detection is earlier or later than this. In other words, if there is a lap, the detection point A of the gas sensor is set to be later than this " _Ts ", and if there is no lap, it is set to be earlier than this " _Ts ". That is, if the weight of the object to be heated can be detected, an average appropriate heating time corresponding to the amount can be determined, but a shorter time than this is calculated as "T _s ".

Now, when the presence or absence of a lap is determined based on the T _s time in this manner, if a lap is found, additional heating is performed by multiplying the T ₁ time to the detection point A by K as in the conventional manner. Also, if there is no lap, the detection time of the first sensor means to the detection point B is ignored,
The control unit monitors only the temperature sensor. Then, detect the detection point B′ where the temperature exceeds a certain threshold α,
Additional heating is performed by multiplying the detection time _T1 up to this point by K.

Here, a thermistor is used as the temperature sensor to detect the temperature of the exhaust gas. Control using such temperature detection has larger variations and is less stable in performance than humidity detection, but on the other hand, it is less susceptible to lapping. Therefore, by combining the two as in the present invention, they compensate for each other's strengths and weaknesses, and excellent automatic cooking can be achieved.

Now, in the embodiments described above, the weight detection is automatically performed by the sensor means provided on the bottom of the heating chamber, but the user may manually input the weight using the timer knob 8 as shown in FIG. In other words, the user sets the weight of the object to be heated by himself/herself. At this time, if heating is started before the weight is set, a constant value may be set as T _s .
Based on this value, it is possible to judge within a certain amount range.

Next, FIG. 7 shows a specific example of the control circuit. The control unit 11 is a microcomputer (hereinafter referred to as "microcomputer").
(abbreviated as). Menu keys and other switches are configured as a key matrix 24, scanned by sweep signals _S0 to _S4 , and input to input ports _I0 to _I3 . 25 is a display section such as a fluorescent display tube, and as shown in FIG.
A predetermined display is performed.

On the other hand, the power supply unit is controlled by the output ports _R0 to _R2 , and the heat source switching relay 26, the output switching relay 27, and the power supply relay 28 are operated. The heat source switching relay 26 switches the power supply between the magnetron 14 and the electric heater 15 . Further, the output switching relay 27 intermittently varies the average output of the magnetron 14 and controls the power supply to the electric heater 15 to keep the heating room temperature constant. The power relay 28 is a main power switch that controls electricity for heating and cooking. These relays are controlled via driver 16.

Door switches 29 and 30 are also connected to the main circuit, and control the power supply to the heat source in response to opening and closing of the door. 23 is a turntable motor, and 17 is a blower fan.

31 is a notification device, which is composed of a buzzer and a voice synthesis circuit. This notifies the user when a key is input or when cooking is complete.

Next, the sensor will be explained. A humidity sensor 32 is used as the gas sensor, and a thermistor 20 is used as the temperature sensor. The humidity sensor 32 is equipped with a refresh heater 33 for burning off dirt, and outputs R ₅ via a relay 34.
is refreshed before the start of cooking. Humidity sensor 32 is pulsed by output _R4 ;
Input to input port A/D ₁ with built-in A/D converter. Thermistor 20 is resistance-divided and input to input port A/D ₀ . Similarly, the weight sensor 23 is also resistance-divided and inputted to the input port A/ _D2 .

FIG. 8 shows an example in which a gas sensor is used as the gas sensor. The gas sensor 35 includes an indirect heater 36, connected in series with a resistor, and inputs a divided voltage to the input port A/ _D1 .

Now, the present invention can be realized with the above configuration.
Next, of the control program of the microcomputer 11, the determination of the presence or absence of a lap will be explained. FIG. 9 shows the main part of the automatic cooking program. First, the microcontroller waits for the menu key to be input (A). When the menu key is input, the system waits for the weight to be set or input manually or by a sensor (B). If the weight is set/input, T _s (w) is set according to the weight (C). This is stored in the ROM of the microcontroller in the form of a table. If there is a next start input, heating will begin (D).

When heating begins, the microcomputer first waits for clock input (E). And if the clock is input
Update the T ₁ counter that counts T ₁ time (F).
Next, the gas sensor determines whether the steam has exceeded a certain threshold (G), and if it is not detected, the temperature sensor determines whether the temperature has exceeded the threshold (H). This determination is made to ensure that even if the gas sensor fails, automatic cooking can be performed using the temperature sensor.

Now, if humidity is detected, then T ₁ time T _s
A determination is made whether it is slower (I). If it is late (T ₁ >T _s ), it is determined that there is a wrap, and this T ₁ is multiplied by a constant K and set in the additional heat time counter (J). And every time clock input (K), KT ₁
The counter counts down (L), and when it counts up (M), heating is automatically terminated.

On the other hand, if it is determined that there is no lap (T ₁ T _s ), each clock input (N) continues.
The _T1 counter is updated (O). and the second
This _T1 time counting continues until the temperature is detected by the sensor means (P). When the temperature eventually exceeds the threshold, at that point the T ₁ time is multiplied by a constant K to determine the additional heat time.

The above is an embodiment in which the presence or absence of a lap is determined based on a humidity sensor or gas sensor and weight information, and an exhaust temperature thermistor is selectively used.

Next, another embodiment of the temperature sensor will be described. FIG. 10 shows an example in which the temperature probe 37 is a temperature sensor. In this embodiment, since the internal temperature of the object to be heated 13 can be directly detected, the variation in finish is smaller than that of an exhaust temperature thermistor. Furthermore, the amount of temperature change is large, which is advantageous in terms of noise resistance. However, it is not possible to automatically cook food without contacting it.

FIG. 11 shows an example in which the infrared sensor 38 is used as a temperature sensor. In this embodiment, the surface temperature of the object to be heated 13 can be measured with considerable accuracy, and the variation in finish is smaller than that of an exhaust temperature thermistor. Also, unlike temperature probes, it can automatically cook food without contacting the food.

Effects of the Invention As described above, according to the present invention, the following effects can be obtained.

(1) By taking weight information into account, the humidity detection sensor can reliably determine the presence or absence of a wrap/lid.
Based on the determination, either the humidity detection sensor or the temperature detection sensor can be selected. Therefore, a stable finish can be achieved regardless of the presence or absence of laps.

(2) Since it can handle three physical quantities: humidity, temperature, and weight, even if one of the sensors fails, automatic cooking can be performed using the combination of remaining sensors. Therefore, safety is dramatically improved compared to conventional systems that use a single sensor or selectively use one of a plurality of sensors.

[Brief explanation of drawings]

FIG. 1 is a perspective view of the main body of a heating device that is an embodiment of the present invention, and FIG. 2 is an enlarged front view of the operation panel.
Fig. 3 is a block diagram showing one embodiment of the present invention, Fig. 4 is a diagram for explaining the difference in the way steam is generated depending on whether or not the device has a wrap, and Fig. 5 a and b are diagrams showing the same wrap. Diagram for explaining the discrimination method, Figure 6 is an enlarged front view showing another operation panel of the device, Figure 7 is a diagram for explaining the discrimination method.
The figure is a control circuit diagram using the humidity sensor of the same device.
The figure is a control circuit diagram using the gas sensor of the same device, No. 9
The figure is a flowchart of the program, FIG. 10 is a block diagram of the same device using a temperature probe, and FIG. 11 is a block diagram of the same device using an infrared sensor. DESCRIPTION OF SYMBOLS 11... Control part, 12... Heating chamber, 13... Heated object, 14... Magnetron, 19... Gas sensor, 20... Temperature sensor, 23... Weight detection sensor means.

Claims (1)

[Claims] 1. A heating chamber that accommodates an object to be heated, a heating means coupled to this heating chamber, a control section that controls this heating means, a gas sensor that detects gas or steam generated from the object to be heated, and It consists of a temperature sensor that directly or indirectly detects the temperature of the heated object, a weight sensor that detects the weight of the heated object, or a weight input means that inputs the weight of the heated object to the control section, Based on the weight of the object to be heated detected by the weight sensor or based on the weight of the object to be heated inputted from the weight input means, the control section determines a normal appropriate heating time that is a function of this weight. A certain shorter time is calculated, power is supplied to the heating means, the output of the gas sensor and the output of the temperature sensor are monitored in parallel, and the normal appropriate time calculated based on the weight of the object to be heated is determined. If the output of the gas sensor exceeds a predetermined value within a certain period of time that is shorter than the normal heating time, the control section determines that the object to be heated is not covered with a wrap or the like, and the gas sensor and continue monitoring until the output of the temperature sensor reaches a predetermined value, count the time required from the time when power supply to the heating means is started until this point is reached, and The total heating time is determined based on the weight of the object to be heated. On the other hand, the normal appropriate heating time calculated based on the weight of the object to be heated is such that the output of the gas sensor within a certain short period of time is a predetermined value. If the temperature does not exceed the temperature, the control section determines that the object to be heated is covered with a wrap or the like, suspends monitoring by the temperature sensor, and causes the output of the gas sensor to reach a predetermined value. In addition to continuing to monitor until the heating means is started, the time required from the time when power supply to the heating means is started until this point is reached, the total heating time is determined based on this, and the power supply to the high frequency generation means is stopped. A heating device configured to