JPH023090B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a cooking device, and particularly to a cooking device that automatically cooks food using a plurality of sensors.

Conventional Structure and Problems Conventionally, in a heating cooker that performs automatic cooking, a number of sensor means have been used to detect the progress of heating the 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. Various sensors are installed in products, such as those that measure the surface temperature of food using a sensor, and those that measure the internal temperature of food using a temperature probe.

In particular, humidity sensors and gas sensors that detect food vapor and gas can be expected to have excellent detection reproducibility and stable results when cooking food that raises the temperature of food to 70 to 100 degrees Celsius. In addition, it has relatively good weight handling, is relatively unaffected by ambient temperature, and can be easily controlled and constructed at low cost.

On the other hand, it takes time to refresh to set the initial conditions for detection, requiring extra waiting time.
For example, in the case of a humidity sensor, in order to burn off dirt on the surface of the sensor element, a heater installed close to the sensor element is energized and the sensor element is heated with this heat (this is called refreshing). This is a necessary procedure before operating the sensor.

Further, in the case of a gas sensor, the sensor element is always heated to about 400° C. and the sensing operation is performed in this state. Therefore, there is no need for refreshing to burn off the dirt on the element, but on the other hand, it is necessary to expel the gas or steam that has accumulated in the heating chamber and replace it with fresh air before starting the detection operation. . This is also called refreshment.

Now, the above-mentioned humidity sensor or gas sensor is a useful sensor for detecting food heating, but as mentioned above, a refresh is always required before performing a detection operation.

Among heating cookers aiming at automatic cooking using such sensors, there have been products on the market that do not heat the food until the food is temporarily refreshed.
However, for microwave ovens aimed at short cooking times, this waiting time (30 seconds to 1 minute) is too long, and there has been a demand for improvement. Recently, an automatic heating cooker that improves this drawback has been proposed.

The contents will be explained using FIG.

First, determine the time interval T _M that will allow the refresh to be completed sufficiently under all weather and power supply conditions. Furthermore,
Taking into consideration the type and amount of food to be heated, determine the heating time T ₁ that is considered to be such that heating will not be completed even after heating starts. At the same time as cooking starts
Heat for T _R and then stop heating until T _M has passed. Then, since refreshing has been completed during this time, it is sufficient to monitor the heating of the food with the sensor by restarting the heating after _TM . Steam is detected at point a, and heating is continued for K (T ₁ + T ₂ ) to complete heating. This control method is generally called K value control. Before the improvement, there was no heating for _T1 , but in this case, the time required for automatic cooking for _T1 has been reduced.

Now, there is a proposal to further reduce the time required for automatic cooking. This will be explained using FIG. Heating is started simultaneously with the start of cooking without interruption during the time _TM required for refreshing the temperature sensor. Foods (particularly small quantities) whose vapor reaches a detectable level before T _M are monitored by a second sensor (eg, a thermistor). In other words, point a at which the heating chamber exhaust temperature reaches a predetermined level α is defined as the detection point, and the heating time required for this point is defined as detection time _T1 , which is multiplied by a constant K determined for each menu. Just add more heat to complete the heating. If there is no detection within _TM , control is performed using a humidity sensor with high detection accuracy as shown in Figure 1. As mentioned above, by using a sensor that requires refreshing and a thermistor together,
It has become an automatic heating cooker that can perform continuous heating and shortens the time required for automatic cooking.

However, there remains a problem with this proposal regarding sensor failure. If the thermistor malfunctions, the food may become overheated, causing problems such as drying or even burning. A similar situation also occurs in the case of a failure of the humidity sensor.

OBJECTS OF THE INVENTION The present invention was made in consideration of solving the above-mentioned conventional problems, and an object of the present invention is to provide a heating cooker that can perform optimal heating even when a sensor fails.

Structure of the Invention In order to achieve the above object, the heating cooker of the present invention combines a temperature sensor or a gas sensor and a temperature sensor that can be expected to operate stably under various condition changes, so that even if one sensor fails, the other The sensor assists in monitoring and controls the heating of the food, and has the effect of ensuring stable food heating even in the event of a sensor failure.

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

FIG. 3 is an external perspective view of a heating cooker that is an embodiment of the present invention. A door body 2 that can be opened and closed is pivotally supported on the front surface of the main body 1. A menu key 4 for selecting a cooking menu is provided on the operation panel 3.

FIG. 4 is a front view of such an operation panel 3.
The user selects a desired menu using the menu key 4. For example, reheated “chilled rice”
Press. Then, “A1” will appear in the top two digits of the four-digit number display, and “Chilled rice” will appear on the display window.
is decoded by the control unit, indicating that the input was made correctly. 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. Numeral 10 is a cancel key for canceling a preset menu or heating pattern, or for stopping cooking in progress.

FIG. 5 is a configuration diagram of the heating cooker. Various instructions input from the operation panel 3 are sent to a microcomputer (hereinafter abbreviated as microcomputer) 1 as a control unit.
1. Based on this instruction, the microcomputer 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 a magnetron 14 and an electric heater 1 are installed as heating means.
5. The magnetron 14 is energized and controlled by the microcomputer 11 through a driver 16. The blower 17 cools the magnetron 14 and at the same time ventilates the heating chamber. Reference numeral 18 denotes an exhaust guide for discharging the exhaust gas to the outside of the aircraft.

Inside the exhaust guide 18, a first sensor means 19 for detecting humidity and a second sensor means 20 for detecting temperature are provided, and the progress of heating is transmitted to the microcomputer 11 via a detection circuit 21. Based on the information from these sensors, the microcomputer 11 determines the heating pattern and at the same time determines the control sensor to automatically control the cooking. Note that 22 rotates the heated object 13,
A turntable 23 for improving uneven heating is a motor that is its driving source.

Now, as already described, until the first sensor means 19 completes refreshing and starts monitoring, the heating pattern of the automatic heating cooker monitored by the second sensor means 20 is in the normal mode shown in FIG. As shown, the microcomputer 11 monitors the second sensor means 20 from O to T _M , and when the temperature reaches the α level, controls the point a as the detection point.
When there is no detection up to T _M , the first sensor means 19 is connected to the microcomputer 1 as shown in the normal mode in FIG.
1 is monitored and the detection point is point b where the steam reaches level β, and additional heat is applied by KT ₁ , which is the heating time T ₁ required for this multiplied by a constant K determined for each menu, and automatic cooking is completed. do.

The above is the control when each sensor means operates normally. Immediately after starting cooking, microcomputer 11
First, the operation of the second sensor means 20 is checked to determine whether it is normal or abnormal. If it is normal, control is performed using the heating pattern and detection method shown in the normal mode of FIG. 2 and the normal mode of FIG. 6.
In the case of an abnormality, the heating pattern is changed to the mode shown in FIG. 1 (abnormal mode), and the second sensor means 2
0 control is not performed, but the control is switched to control using only the first sensor means 19 and automatic cooking is performed.

Next, FIG. 7 shows a specific example of the control circuit. 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 . Reference numeral 25 denotes a display section such as a fluorescent display tube, which provides a predetermined display as shown in FIG.

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 29 intermittently varies the average output of the magnetron 14 and controls the power supply to the electric heater 15 to keep the heating chamber temperature constant.

The power relay 28 is a main power switch that controls power supply to the cooking device. 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 ventilation fan. Reference numeral 31 denotes an annunciator, 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 is used as the first sensor means 19, and a thermistor is used as the second sensor means 20. The humidity sensor of the first sensor means 19 is equipped with a refresh heater 33 for burning off dirt and is refreshed at the start of cooking by an output _R5 via a relay 34. The humidity sensor of the first sensor means 19 is pulsed by the output R ₄ and is connected to the input port A/D with a built-in A/D converter.
Entered into D ₁ . Thermistor 20 is resistance-divided and input to input port A/D ₀ .

An abnormality in the thermistor of the second sensor means 20 is determined as a shot defect when the voltage input to the input port A/D ₀ is smaller than a predetermined threshold value Va, and as an open defect when it is larger than the threshold value Vb. This is determined by the microcomputer 11 and the mode is changed as described above. Furthermore, an abnormality in the humidity sensor of the first sensor means 19 is determined by the microcomputer 11 to be defective if the signal input to A/D ₁ at the time of refreshing is equal to or higher than a predetermined threshold V _R , and the time T _M Even after the elapse of time, the signal of the thermistor of the second sensor means 20 continues to be monitored, and K value control is performed. 1st
By setting the K value to a different value for the humidity sensor of the sensor means 19 and the thermistor of the second sensor means 20, the total heating time can be set to an optimal value, ensuring good heating of the food. .

FIG. 8 is a flowchart of the program of the control section 11 in this embodiment, and FIG. 11 is a block diagram of the control section 11 and its peripheral parts. Microcomputer 1
1, when the start button 6 is operated, the counter 11a counts the heating time _T1 time at the same time as heating starts (A). Next, the sensor abnormality determination unit 11b determines whether the thermistor of the second sensor means 20 is normal (B), and if it is normal, it is determined that T ₁ is less than or equal to T _M (C), and temperature detection is waited for (D). If detected, the second sensor means 2
Product with the K constant determined for a thermistor of 0
K′T ₁ is set in the calculation unit 11c (E), and the comparison unit 11
When f confirms that the required heating time has elapsed (F), a signal is sent to the magnetron control output section 11g to end the heating (H). The count by the counter 11a is T ₁ >
If T _M (C), the selection unit 11e selects the signal from the calculation unit 11d, and the sensor abnormality determination unit 11b determines whether the humidity sensor of the first sensor means 19 is normal (I); Wait for humidity detection (J). If humidity is detected, KT ₁ is set in the calculation section 11d.
(K), when the comparison section 11f confirms that the necessary heating time has elapsed (G), a signal is sent to the magnetron control output section 11g, and the heating is completed (H). When the thermistor of the second sensor means 20 is determined to be abnormal by the sensor abnormality determination section 11b (B), a heating sequence in an abnormal mode is set by the selection section 11e (L), and the humidity as the first sensor means 19 is determined to be abnormal. The sensor abnormality determination unit 11b determines whether the sensor is normal or not (I). 1st
If the humidity sensor of the first sensor means 19 is also abnormal, the sensor abnormality determining section 11b sends a signal to the magnetron control output section to immediately end the heating (H), and the sensor abnormality determining section 11b detects the humidity sensor as the first sensor means 19. If it is determined to be normal, humidity detection (J) and later (K) ~
(H) is the same as above. The thermistor of the second sensor means 20 is normal (B), and the count of the counter 11a is
When T ₁ > T _M , the sensor abnormality determination unit 11 passes through (C).
If the humidity sensor of the first sensor means 19 is abnormal in the judgment of b (I), the thermistor of the second sensor means 20 is controlled and waits for temperature detection (D), and if detected, the calculation unit After setting K′T ₁ in step 11c (E), heating is completed as described above (H).

The above is an example in which a humidity sensor and a thermistor for detecting exhaust temperature are combined.

Next, another embodiment of the second sensor means will be described. FIG. 9 is a configuration diagram of an embodiment in which a temperature probe 35 is used as the second sensor means. 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 a thermistor that detects the exhaust temperature. Furthermore, the amount of temperature change is large, which is advantageous in terms of noise resistance.

FIG. 10 is a configuration diagram of an example in which the infrared sensor 36 is used as the second sensor means. In this embodiment, the surface temperature of the heated object 13 can be measured with high precision, and the variation in finish is smaller than that of an exhaust temperature thermistor. Further, since the measurement can be performed without contact, it is easy to reduce heating unevenness by using the turntable 22.

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

Even if the second sensor means fails, automatic cooking can be performed by the first sensor means, and even if the first sensor means fails, automatic cooking can be performed by the second sensor means. It is now possible to provide an automatic heating device that guarantees the perfect finish.

[Brief explanation of drawings]

Fig. 1 is a diagram explaining the operation (normal mode) of a conventional heating cooker, Fig. 2 is a diagram explaining other conventional operations, and Fig. 3 is a diagram explaining the operation of a conventional heating cooker (normal mode). 4 is a front view of the operation panel, FIG. 5 is a configuration diagram, FIG. 6 is a diagram explaining the uninterrupted heating pattern (normal mode), and FIG. 7 is a perspective view of the main body.
The figure shows a control circuit diagram using the same humidity sensor and thermistor, FIG. This figure is a block diagram showing another embodiment of the present invention in which an infrared sensor is used as the second sensor means, and FIG. 11 is a block diagram showing the control section and its surroundings. 11... Microcomputer, 12... Heating chamber, 13... Heated chamber, 14... Magnetron (heating means), 15... Electric heater (heating means),
19...first sensor means, 20...second sensor means.

Claims (1)

[Scope of Claims] 1. A heating chamber for storing an object to be heated, a heating means for heating the object to be heated, a control section for controlling the heating means, and a heating chamber for storing an object to be heated, a control section for controlling the heating means, and a heating chamber for storing an object to be heated, a control section for controlling the heating means, and a heating chamber for storing an object to be heated, a heating means for heating the object to be heated, a control section for controlling the heating means, and a heating chamber for storing an object to be heated. The first step is to detect different physical quantities emitted from heated objects.
and a second sensor means, the second sensor means detects a physical quantity for a time shorter than a predetermined time T _M , and the first sensor means detects a physical quantity for a time longer than a predetermined time T _M. One of the sensor means works as the main sensor means to prioritize the heating situation, detect the physical quantity, and use the output for control, and the other sensor means works as the auxiliary sensor means, and if there is an abnormality in the main sensor means, The cooking device is configured to perform heating control based on the output signal of the auxiliary sensor means when such occurrence occurs. 2. The heating cooker according to claim 1, comprising a gas sensor or a temperature sensor as the first sensor means. 3. The cooking device according to claim 1, further comprising a temperature sensor for detecting the ambient temperature of the heating chamber as the second sensor means. 4. The cooking device according to claim 1, further comprising an infrared sensor as the second sensor means for detecting the surface temperature of the object to be heated. 5. The cooking device according to claim 1, further comprising a temperature probe for detecting the internal temperature of the object to be heated as the second sensor means.