JPS6029522A - Electronic range - Google Patents

Abstract

PURPOSE:To enable to automatically perform optimum cooking with a simple operation by a method wherein optimum heating time for various foods are automatically determined based upon obtained times for the output of a finishing sensor to reach predetermined levels. CONSTITUTION:Based upon the arrival times T1 and T2, which are the times for the output of an absolute humidity sensor to require to reach previously set detection levels V1 and V2 in order since the start of the heating of a food, a heating state characteristic value to represent the heating state of the food in calculated in terms of T2-T1 so as to obtain the difference between the calculated T2-T1 and the pre-set reference characteristic value in order to determine a coefficient of heating time (k) and to control the heating of an electronic range. The coefficient of heating time is set in advance in the RAM of a control circuit on the average over each food in the form of a coefficient table of heating time. Consequently, the heating time optimum for various foods is automatically determined based upon the time for the output of the finishing sensor to require to reach the predetermined levels, resulting in eliminating the effort to select a food selection key or enabling to automatically perform optimum cooking with simple operation.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a microwave oven that automatically cooks food by detecting water vapor, gas, etc. generated from heated food and controlling heating time.

<Prior Art> In automatic cooking microwave ovens, a finish sensor installed near the open exhaust port detects water vapor generated as food is heated, and automatically controls the finish of the food. However, although conventional microwave ovens automatically control the finish, for example, when cooking spinach, you press the "Prepare" key, or when heating coffee, press the "Warm" key.
It is necessary to select one of the many food selection keys provided on the operation panel according to the MH of the food to determine the cooking time, which is cumbersome and has the disadvantage that cooking may fail due to incorrect selection. there were. Moreover, when cooking using a microwave oven, food is generally covered with a lamp, but when the lamp is covered, the finishing time is different from when the lamp is not covered. For this reason, if a selection key was added to select whether or not to turn on the lamp, there was a problem in that the range operation would become even more complicated.

<Object of the Invention> In view of the above-mentioned problems, the present invention measures the time for the output of the finish sensor to reach a predetermined level, and automatically determines the optimal heating time for various foods from that time. To provide a microwave oven that can perform optimal automatic cooking with simple operations without the trouble of selecting a food selection key.

<Structure of the Invention> The present invention has been made by focusing on the fact that the level change of the detection signal of the finished sensor differs depending on the type of food, and two detection levels v1. arrival time detection means for detecting arrival times T1 and T2 at which the output of the finish sensor reaches each level of V2 in sequence; heating state characteristic value calculating means for calculating a heating state characteristic value from the arrival times TI and T2; a characteristic value comparison means for comparing the heating state characteristic value calculated by the calculation means with a preset reference characteristic value; and a heating time for determining the heating time after reaching the detection level V2 based on the comparison result of the characteristic value comparison means. The heating state characteristic value is calculated and the optimum heating time is determined depending on the type of food by comparing the characteristic value with the reference characteristic value.

<Example> Figure 1 is a front view of a microwave oven which is an example of this invention.
FIG. 2 is a schematic side sectional view of the microwave oven, and FIG. 3 is a schematic circuit diagram of a control section of the microwave oven.

A front operation panel 2 of the microwave oven body 1 is provided with a heating key 3 for instructing the start of heating by microwaves. An oven 5 for storing food to be cooked 8 is provided inside the microwave oven main body 1, and the oven 5 is opened and closed by a door 9. In this example, an absolute humidity sensor 7 is used as the finishing sensor, and the absolute humidity sensor 7 is placed close to the exhaust port 6 formed in the oven 5.

Hereinafter, the control section of the microwave oven will be explained with reference to the schematic circuit diagram shown in FIG.

The central control circuit 12 consists of a CPU, ROM, and RAM.
Controls cooking in the microwave according to the program stored in the ROM. In order to perform food heating control, which will be described later, a standard detection level V1. A table containing the value of v2, the reference characteristic value t, and the heating time coefficient is stored in advance. The absolute humidity sensor 7 includes a series circuit of an open type thermistor R1 and a closed type thermistor R2, and resistors R3 and R.
The amplifier 10 includes a bridge circuit 11 in which a series circuit of 4 and 4 are connected in parallel, and an amplifier 10 whose input terminals are connected to output terminals A and B of the bridge circuit 11. Bridge circuit 1
A DC power supply 9 is connected to the input terminal of 1 through a current control resistor Rs.
is connected. As the food is heated, water vapor, gas, etc. generated from the food gradually increase, and the resistance value of the thermistor R1 changes. When the resistance value of the thermistor R1 changes, the output voltage vb between the output terminals A and B changes, so the detection signal of the absolute humidity sensor 7, which can be obtained as the output voltage of the amplifier 1 (1), changes. 7 outputs a detection signal whose output level changes as time passes for heating the food, and corresponds to the heating state at that time.

The output voltage Va of the absolute humidity sensor 7 is given to the central control circuit 12 via the A/D converter 17 and the interface (1/F) 13. The input unit 14 including the heating key 3 provides a heating start signal to the central control unit 12 via the interface 13 when the heating key 3 is operated. The microwave that heats the food in oven 5 is magnetron 1.
Generated by 5. The relay 16 receives a control signal from the central control circuit 12 via the interface 13 to turn on and off, thereby turning on and off the power of the magnetron 15.

Heating control in the microwave oven with the above configuration is performed when the output of the absolute humidity sensor 7 reaches the set detection level v1 after the start of heating the food. Arrival time 'ri when reaching v2 in order,
From T2, calculate (T2 Tl) as a heating state characteristic value representing the heating state of the food, and determine the heating time coefficient k by comparing the calculated (T2 Tt) with a preset standard characteristic value t. It will be done as follows. Furthermore, the arrival time TI,
A plurality of heating time coefficients k are set in advance according to the relationship between the heating state characteristic value (T2 Tl) obtained from T2 and the reference characteristic value t, and stored in the RAM of the central control circuit 1 as a heating time coefficient table. There is. Further, the detection levels v, , v2 are set by averaging the level values of the region where the sensor output rises before the heating of the food is completed for each food.

Generally, the output characteristics of the absolute humidity sensor 7 differ depending on the type of food. For example, FIG. 4 shows output voltage Va vs. heating time characteristics of the absolute humidity sensor 7 for two different foods. As can be seen from this characteristic diagram, the time it takes to reach the detection level V1+v2 differs for different foods, which results in different heating state characteristic values (T2 Tl).
Utilizing this fact, the heating time after reaching the detection level v2 can be determined. In other words, the heating state characteristic value (
Determine the difference between T2-Ts) and the reference characteristic value t, determine the heating time coefficient k from the heating time coefficient table according to the difference, and obtain the total heating time T that allows optimal heating from kx'r2. . Of course, different heating time coefficients are determined for each food product having different output characteristics a and b, as in the case of FIG. 4, and the optimum total heating time for each food product is obtained.

Next, the control operation for heating food in the microwave oven will be explained.

After setting the food in the oven 5, turn on the heating key 3 and send the heating start signal from the input section 14 to the central control circuit 1.
Give to 2. This causes the central control circuit 12 to relay 1
6 is output, and relay 16 is turned on. When the relay 16 is turned on, the magnetron 15 oscillates and generates microwaves, and the food inside the open 5 is heated by the microwaves. As time passes during this microwave heating, water vapor or the like is generated from the food and is detected by the absolute humidity sensor 7. Next, the time T 1 + T 2 from the start of heating until the output of the absolute humidity sensor 7 reaches the detection level ■1 + "2 is determined, and the heating time coefficient k is selected based on the determination process described above to determine the total heating time. T is determined, and heating is continued until the total heating time T has elapsed. When the total heating time T has elapsed, the relay 16 is turned off, the magnetron 15 is stopped, and the heating of the food is completed.

The above operation determines the optimal total heating time T depending on the type of food and automatically performs cooking/heating, so the operator is freed from the hassle of selecting the food selection key, and moreover, the operator is freed from the trouble of selecting the food selection key, and is free from the trouble of cooking due to operational errors. You can reliably perform the desired cooking without making any mistakes.

The above-mentioned microwave oven provides comfortable cooking and heating depending on the type of food, but the output characteristics of the absolute humidity sensor 7 are different even when the food is covered with plastic wrap and when it is not. As in the case of different cases, it is determined whether the lamp is covered or not, and optimal additional heating is performed to automatically cook the food. However, in general, when the amount of food to be heated is small, the characteristics a and b shown in Figure 4 above show changes when the food is covered with plastic wrap and when it is not covered, respectively, but when the amount of food is large, The difference in changes shown in FIG. 5 occurs when the lamp is covered and when it is not covered. When the amount of food is small, by covering it with plastic wrap, the characteristic a shown in Figure 4 can be achieved.
The heating state characteristic value (T2 Tt) decreases as follows. On the other hand, if there is a large amount of food, if you cover it with plastic wrap, the time T1' to reach the detection level ■1 will be longer.
Characteristic d where T1' is longer than characteristic C when the lamp is not covered
shows. That is, when the amount of food is large, the heating state characteristic value (T2'TI') when the wrap is covered is greater than the heating state characteristic value when the lamp is not covered, compared to when the amount of food is small. In this way, the difference in time to reach each detection level depending on the amount of food when covered with plastic wrap (
When considering the difference in T2'-TI), (T2-Tt)/T+ may be used as the heating state characteristic value. This heating state characteristic value (T2-71)/T1 is a parameter that takes into account the variation in the time TI (T1') to reach the first detection level V1, so as in the previous example, the temperature of the food It is possible to perform optimal cooking and heating according to the type of food, accurately determine the presence or absence of a lamp regardless of the amount of food, determine the heating temperature coefficient ', and optimize the total heating time T'(-' × T2' ) can be determined.

<Effects of the Invention> As described above, according to the present invention, it is possible to automatically determine the optimal heating time depending on the food based on changes in the detection level of the finish sensor as the food is heated, thereby eliminating the need for cumbersome food selection keys. Automatic cooking is possible without any operation,
Moreover, it has the advantage that the presence or absence of wrap can be determined in the same way as the different types of food, and optimal cooking and heating can be performed without specifying whether wrap is present.

[Brief explanation of the drawing]

1 Figure 1 is a front view of a microwave oven that is an embodiment of this invention.
Fig. 2 is a schematic side sectional view of the microwave oven, Fig. 3 is a schematic circuit diagram of the control unit of the microwave oven, and Fig. 4 is the output of the absolute humidity sensor 7 used in the microwave oven for two types of foods. Figure 5 is an output voltage-heating time characteristic diagram showing the relationship between the voltage Va and the heating time, and shows the difference in the output voltage Va and the heating time when the food is the same and the amount is large, and shows the difference in changes depending on whether there is a wrap or not. It is an output voltage-heating time characteristic diagram showing the relationship. 3 - heating key, 7 - absolute humidity sensor (as finishing sensor), 12 - central control circuit. Applicant Sharp Corporation Agent Patent Attorney Hisao Komori 2

Claims (1)

[Claims] (11) In a microwave oven that automatically cooks and heats food by detecting water vapor, gas, etc. generated from heated food with a finish sensor, two
arrival time detection means for detecting arrival times TI, T2 at which the output of the finish sensor reaches each of the two detection levels Vi, v2 in sequence; heating state characteristic value calculation means for calculating a heating state characteristic value from T2; characteristic value comparison means for comparing the heating state characteristic value calculated by the calculation means with a preset reference characteristic value; and heating time determining means for determining the heating time after reaching the detection level (1) 2 based on the comparison result. (2) The microwave oven according to claim 1, wherein the heating state characteristic value is the difference (T2 Tl) between the arrival times T1 and T2. (3) The microwave oven according to claim 1, wherein the heating state characteristic value is a ratio of the arrival time T2 to the arrival time T1 (T2 Tl)/T1.