JPS59221527A - Heating unit - Google Patents

Abstract

PURPOSE:To make it possible to carry out appropriate heating regardless of the existence or non-existence of a wrap or a lid by discriminating the existence or non-existence of a wrap or a lid by a humidity sensor or a gas sensor, and controlling the temperature by a temperature sensor when no wrap exists. CONSTITUTION:A material 13 to be heated is placed in a heating chamber 12, and is heated by a magnetron 14 and an electric heater 15. The magnetron 14 is controlled of the power supply by the control part 11 through a driver 16. A blower 17 cools the magnetron 14 and carries out ventilation within the heating chamber 12. First sensor means 19 capable of detecting the humidity and second sensor means 20 capable of detecting the temperature, are provided within an exhaustion guide 18, and transmits the progressing state of the heating to a control part 11 through a detection circuit 21. The control part 11 performs discrimination of the wrap based on information pieces of these sensors to select sensor means to be used.

Description

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

2. Description of the Related Art Conventional Structures and Problems Conventionally, in heating apparatuses capable of automatic cooking, various sensors have been used to detect the progress of heating an object. 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 reproducibility of detection and can be expected to produce stable results during cooking in which the temperature of food is raised to 70 to 100°C. It is also less susceptible to the effects of food placement position and power supply voltage, and operates stably even in relatively high-temperature environments. The control circuit is also simple, highly reliable, and inexpensive.

On the other hand, the detection time differs depending on whether the food is covered with plastic wrap or a lid or not.

FIG. 4 is a graph showing such a state and shows how steam is generated from reeds and food. If there is a wrap, the steam will stay within the wrap at the beginning of heating and will not blow out into the heating chamber. Eventually, as the pressure inside the wrap increases,
Finally, at point A, the steam pushes away the plastic wrap and blows out into the heating chamber. This is the detection point, and the detection time at this time is T1. 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 V value of c at point B quickly. The detection time T1' at this time is shorter than the detection time T1 when there is a lap. In other words, if there is no plastic wrap, it will break quickly.

Generally, in automatic cooking using sensors, a method called K value control is adopted. This is to apply additional heat for a certain period of time after the detection time T1 has elapsed, and the additional heat 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 the lamp foot and the non-wrap in the optimal time.

In this way, humidity sensors and gas sensors can operate stably under various changes in conditions, but at this time, the presence or absence of a wrap or a lid must be limited 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. 126294/1983 discloses a control system that combines a gas sensor and a temperature sensor. This automatically cooks by switching sensors depending on the menu.For example, a gas sensor detects alcohol in a sake can, and a temperature sensor detects the exhaust temperature of the heating chamber for reheating. , Krill detects gases generated from burnt food. Therefore, the above-mentioned invention cannot 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 solves 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 a lid.

Structure of the Invention In order to achieve the above object, the heating device of the present invention combines a humidity sensor or gas sensor, which can be expected to operate stably under various conditions changes, and a temperature sensor. If there is no wrap, the structure is controlled by a temperature sensor. If there is a wrap, a humidity sensor or gas sensor can be used to achieve a stable finish, and if there is no lamp, a temperature sensor can be used to control the process. This has the effect of preventing

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 supported on the front surface of the main body 1 so as to be openable and closable. A menu key 4 for selecting a cooking menu is provided on the operation spring /I/3.

FIG. 2 is a detailed view of the operation panel 3.

The user selects a desired menu using the menu key 4. For example, press "cold rice" for reheating.

Then, rr R7y'' appears on the display window 5 in the upper two digits of the 4-line numeric display, indicating that cold rice has been coded by the control unit and has been validly input.

If the nutato button θ is then pressed, automatic cooking will start.

In addition to this, there is a mode setting key 7 for manual cooking, a timer knob 8, and an excessive setting key 9 on the operation spring /l/3.
are arranged. 1o is a cancel key that cancels the preset menu or heating pattern and stops the cooking in progress.

Now, FIG. 3 is a block diagram showing the configuration of such a heating device. Various commands input from the operation spring/I/3 are
It is decoded by the control unit 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〃S 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 also 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, a first sensor means 19 capable of detecting humidity and a second sensor means 20 capable of detecting temperature are provided. tell. The control unit 11 performs lap determination, which will be described later, based on the information of these sensors, and selects the sensor to be used.

Note that 22 is a turntable for rotating the object to be heated 13 to improve uneven heating, and 23 is a motor serving as its driving source.

Now, as already described, the way in which steam is generated from the 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 wrap 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 a lamp.

First, the wrap discrimination method shown in FIG. 5 will be explained.

This is provided with a counter that counts a certain period of time "Ts" from the start of heating, and the presence or absence of wrap is determined based on whether detection is early or late.

If there is a lap, the detection point A of the first sensor means is set to be slower than this "Ts", and if there is no wrap, it is set to be faster than this "Ts". Specifically, for products with high frequency and high power of 600 watts, Ts 21 minutes 30
In seconds, it was possible to determine the presence or absence of food wrap in a range of 150 to 400 grams.

At this time, as the first sensor means, a humidity sensor Perfumi Ceram (manufactured by Matsushita Electric Industrial Co., Ltd.; trade name) was used.

For small amounts of water droplets, such as 150 grams or less, steam may be released within Ts (1 minute 30 seconds) even if wrapped, and conversely, for large amounts of water droplets of 400 grams or more, even without plastic wrap, steam may be released within Ts (1 minute 30 seconds). (30 seconds), detection may be delayed. Tsume 9: 150g to 400g can be reliably determined
in the range of grams.

However, the quantity range most commonly used for reheating, etc., almost corresponds to this, and there is no problem in practical use. Of course, the amount band can be adjusted by modifying the Ts time.

In this way, when the presence or absence of a slag is determined based on the Ts time, if there is a lap, additional heat is conventionally performed by multiplying the T1 time to the detection point A by K. If there is no lap, the detection time of the first sensor means up to the detection point B is ignored, and the control section monitors only the second sensor means. Then, a detection point B' where the temperature exceeds a certain threshold value α is detected, and additional heating is performed by multiplying the detection time T1 up to this point by K.

Here, a thermistor is used as the second sensor means 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 the influence of lamps. Therefore, if the two are combined as in the present invention, the advantages and disadvantages of each will complement each other, and excellent automatic cooking can be realized.

FIG. 6 shows another lap discrimination method. First, the time t/T l+ until the steam starts to rise is counted, and then the time "t" until the steam exceeds the threshold value is counted. If we take the quotient "T/l" between the two, this value will be larger in the lap foot. Since the steam suddenly blows out into the heating chamber, t is shorter than T.

When the determination level was set to 2.5 and it was determined that if T/t was larger than this, the lap was completed, only 7 out of 103 cases were misjudged.

Next, FIG. 7 shows a specific example of the control circuit. The control unit 11 is a microcomputer (hereinafter abbreviated as "Microcomputer J")
Consists of. Menu keys and other switches are configured as a key matrix 24, and sweep signals SO~
The data is scanned by S4 and input to input ports Io to Io to Io3. 25 is a display section such as a fluorescent display tube, which displays a predetermined display on the display window 5 as shown in FIG.

On the other hand, control to the power supply unit is performed by the output capo-1-Ro to R2, including the heat source switching relay 26, the output switching relay 2,
Activate the power relay 28. The power switching relay 26 is
The power supply is switched 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 chamber temperature constant. Power relay 28 is a main power switch that controls power supply to the heating 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 of the power source 5 in response to opening and closing of the door. 23
1 is a turntable motor, and 17 is a blower fan.

Reference numeral 31 is a notification device, which includes a buzzer and a voice synthesis circuit. This notifies the user when key power is on or when cooking is complete.

Next, the sensor will be explained. A humidity sensor 32 is used as the first sensor means, and a thermistor 2Q is used as the second sensor means. The humidity sensor 32 is connected to a glue fresh heater 33 to burn off dirt.
4Afa L is refreshed by output R5 via relay 34 before starting cooking. The humidity sensor 32 is pulse-driven by the output R4 and is input to an input port A/D+ having a built-in A/D converter. The thermistor 20 is resistance-divided and input to the input capacitor (A/Do).

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

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 wrap will be explained. FIG. 9 shows the main part of a program that implements the discrimination method shown in FIG.

First, the microcontroller waits for clock input (A). Then, when the clock is input, the T1 counter that counts the T1 time is updated (B). The first sensor means then determines whether the steam exceeds a certain threshold (C);
If not detected, the second sensor means determines whether the temperature exceeds a certain threshold (D). This determination is made in consideration of the possibility that even if the first sensor means fails, automatic cooking can be performed by the second sensor means.

Now, if humidity is detected, it is then determined whether the T1 time is slower than Ts (E).

If it is late (T+)Ts), it will be determined that there is a lap foot, and the T
1 is multiplied by a constant K and set in the additional heat time counter (F). And every time there is a clock input (G), xT
The iT1 count is counted down (H), and when it is counted up (I), heating is automatically terminated.

On the other hand, if it is determined that there is no wrap (T+ /, Ts), then (J) continues T1 every time the clock is input.
The counter is updated (K). and T1 until temperature detection is performed by the second sensor means (L).
Time counting will continue. When the temperature eventually exceeds the threshold, at that point the T1 time is multiplied by a constant K to determine the additional heat time.

FIG. 10 shows the main part of a program that implements the discrimination method shown in FIG. To explain only the blocks different from those in FIG. 9, T, t, and T1 counters are updated every time a clock is input. As described in FIG. 6, T stops when the steam starts to rise, and the t counter starts from there.

After the humidity is detected, it is determined whether T/t is greater than a certain threshold value β (E). If it is large, it is determined that there is a lamp foot (T/l > β).

The subsequent control is the same as the previous one.

The above is an example in which a humidity sensor or a gas sensor and an exhaust temperature therminutor are combined. Next, another embodiment of the second sensor means will be described.

FIG. 11 shows an example in which a temperature probe 3 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, it is possible to directly detect the internal temperature of the heated object 13.
<I feel slightly depressed. 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. 12 shows an example in which an infrared sensor 38 is used as the second sensor means. 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 the exhaust temperature therminuta.

Also, unlike temperature probes, it can automatically cook food without touching it.

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

(1) Depending on the presence or absence of a wrap or a lid, either a humidity detection sensor or a temperature detection sensor can be selected. Therefore, a stable finish can be achieved regardless of the presence or absence of a lamp.

(2) Even if the humidity detection sensor fails, automatic cooking can be performed using the temperature detection sensor. Therefore, the safety is dramatically improved compared to the sensor error countermeasure using a time limiter, which has been widely used in the past.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of the main body of a heating device which is an embodiment of the present invention, Fig. 2 is an enlarged front view of the operation panel, Fig. 3 is a configuration diagram of the device, and Fig. 4 is a wrapper in the device. A diagram showing how to determine the difference in the way steam is generated depending on whether it is present or not. Figure 7 is a control circuit diagram using the humidity sensor of the same device. Figure 8
The figure is a control circuit diagram using the gas sensor of the same device, Figure 9 is a flowchart of a program that implements the lap discrimination method shown in Figure 5, Figure 10 is a flowchart of a program that implements the lamp discrimination method shown in Figure 6, and Figure 11. 12 is a configuration diagram of the same device using a temperature probe, and FIG. 12 is a configuration diagram of the same device using an infrared sensor. 11...Control unit, 12...Heating chamber, 13
... Heated object, 14 ... Macnetron, 19 ... First sensor means, 20 ...
Second sensor means. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figures 2, 3, 4, 5, 6, 9

Claims (5)

[Claims] (1) A heating means for heating an object to be heated, a control section for controlling the heating means, a first sensor means for detecting gas or steam generated by the object to be heated, and a temperature of the object to be heated. and a second sensor means for directly or indirectly detecting the generation of steam, and the control section uses the first sensor means to determine a change over time in the occurrence of steam generation, and based on the determination, the control section Alternatively, a heating device configured to selectively use a second sensor means to control the heating means. (2) The heating device according to claim 1, comprising a gas sensor or a humidity sensor as the first sensor means. (3) The heating device according to claim 1, further comprising a humidity sensor for detecting the atmospheric temperature inside the refrigerator as the second sensor means. (4) The heating device according to claim 1, further comprising an infrared sensor for detecting the surface temperature of the object to be heated as the second sensor means. (5) The heating 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.