JPH0638359B2 - High frequency heating device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to automation of heating in a high-frequency heating device, and relates to a control system for optimally heating an object to be heated using a sensor.

2. Description of the Related Art As a prior art for automating heating using a sensor, Japanese Patent Application Laid-Open No. 51-134951 is well known.

This detects the change in humidity generated from the object to be heated, and makes the time when it reaches a certain set value the vapor detection point. The total heating time is the sum of the product KT ₁ of the heating time T ₁ required to reach it and the coefficient K peculiar to the object to be heated, which is separately determined.

This is an example of automatic heating control using a so-called humidity sensor, but it is also an extremely effective control method for a so-called gas sensor that reacts with steam, alcohol, and carbon dioxide.

Problems to be Solved by the Invention However, in such a conventional automatic heating method, if the object to be heated is large or is frozen, heating unevenness peculiar to high-frequency heating occurs and the locally overheated portion is generated. The generated vapor reaches the detection set value. Therefore, the heating of the object to be heated is completed before it is sufficiently heated.

For example, in a microwave oven, reheating (reheating) of food is often used. At this time, the food may or may not be covered with a plastic sheet (wrap). At this time, the detection points are considerably different depending on the presence / absence of the cover, and in the method according to Japanese Patent Laid-Open No. 51-134951,
I can't heat it well.

Further, in the thawing cooking of frozen foods, there is a large difference in the dielectric loss of ice and water, and microwaves are intensively absorbed in the melted portion, so local boiling is likely to occur. For this reason, in the method disclosed in Japanese Patent Laid-Open No. 51-134951, it was easy for an unthawed part to remain in the center due to food.

An object of the present invention is to provide a heating pattern that solves the above-mentioned conventional drawbacks, and can provide an excess or deficiency of heating depending on the presence or absence of a cover in reheating, and a temperature unevenness of heating of frozen foods in thawing cooking. .

Means for Solving the Problems The high-frequency heating device of the present invention, when heating an object to be heated,
The control unit that includes a sensor that detects at least water vapor generated from the object to be heated, and that controls the power supply to the high-frequency generation unit has at least two sensor detection thresholds and a counter unit.

Operation The high-frequency heating device of the present invention first continues to heat the object to be heated with a constant high-frequency output, detects at least a slight amount of water vapor from the food with the sensor, and detects at this first detection point. When it reaches, the high frequency output is switched to continue heating. Then, it is detected by the sensor that at least water vapor from the object to be heated further increases to a predetermined amount, and the total heating time required up to the second detection point is counted by the counter means. Control the end of heating.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 is a perspective view of the high frequency heating apparatus according to the present invention.
A door body 16 is pivotally supported on the front surface of the main body 15 so as to be openable and closable, and an operation panel 1 is arranged. An automatic cooking key 2 is provided on the operation panel 1.

FIG. 3 is a block diagram showing an embodiment of the configuration of the present invention. The command input from the automatic cooking key 2 on the operation panel 1 is decoded by the control unit 3. Then, the control 3 starts cooking the food, which is the object to be heated 12 placed in the heating chamber 10. The heating is controlled by supplying power to the magnetron, which is the high-frequency generating means 7, through the driver 4.

As for heating, first, microwave heating with high output is performed as shown in FIG. 1, and is switched to low output according to the progress of the heating state of the food (FIG. 1a). The food 12 is roughly heated during the initial high power micro-heating. The fan 6, which is a ventilation means, discharges the steam generated from the food 12 to the outside of the machine body, and the sensor 9 provided in the exhaust guide 8 detects that a small amount of water vapor or gas comes out from the food, and controls it from the detection circuit 5. The detection signal is transmitted to the unit 3. At the time point P _{1 when} it is detected that the amount of water vapor coming out from the food reaches the first threshold value Δh, the control unit 3 switches the power for heating the food and performs microwave heating with low output. (Fig. 1b).

Here, the reason why the heating capacity is switched from the high output to the low output is as follows. The food is roughly heated by the initial high output, and heating is advanced in only one part located in the strong electric field part as compared with the other part. If heating at high output is continued in this state, steam is rapidly released from this part, and most of the food reaches the detection point before it is sufficiently warmed. In other words, it will be early cut.

Therefore, switching from a high output to a low output waits for heat conduction from a portion where local overheating is proceeding to spread to another portion. At the same time, if the fan 6 is continuously rotated at this time, a small amount of steam locally generated due to overheating is promptly discharged to the outside of the machine body.

Then, while continuing the heating by the low output, if the heat conduction inside the food reaches the maximum, the temperature of the whole food will rise,
The amount of steam or gas emitted from food per unit time increases rapidly. The sensor 9 provided in the exhaust guide 8 detects that the rapidly increasing water vapor reaches the second threshold value A · α,
The control unit 3 will determine the second detection point P ₂ .
(A is an initial value, α is a coefficient). Here, the sensor 9 indicates that the amount of water vapor, which has rapidly increased since the start of heating the food, reaches a predetermined amount.
To the original but the time T ₁ until the detection, follow the heating time KT
₁ is calculated. Here, the K value is a cooking constant.

Then, according to a command from the control unit 3, the power supply to the magnetron, which is the high-frequency generator 7, is controlled via the driver 4.

In this way, high-power heating until a slight amount of steam is detected, low-power heating until a rapidly increasing amount of steam is detected, and additional heating based on the time required until a rapid increase in steam is detected are performed. When the three types of heating modes are completed, the automatic food cooking is completed.

As the sensor 9, a gas sensor manufactured by Figaro, a humidity sensor "Humicellum" manufactured by Matsushita Electric Industrial Co., Ltd., or an absolute humidity sensor "Neo-Humicellum" can be used. 5 is a detection circuit of these sensors, 13 is a plate 11
Is a motor that is driven to rotate to improve uneven heating.

Next, a flow chart which is an example of a control program when this control unit is configured by a microcomputer will be described with reference to FIG.

First, the initialization program RUNs and the RAM is cleared and the output port is reset (A). Next, clocks are counted and basic data for various counters is created.
(B). In the case of a counter with a built-in counter, this is executed by hardware. Subsequently, the display data is output to perform a predetermined display on the display unit (C). Since dynamic lighting is generally used, display data is created for this purpose. Then, it is checked whether the heating device is in operation (D), and when it is not in operation, the key input is taken and its decoding is performed (E). The operations of the automatic cooking key and the start are decoded and processed here.

If it is confirmed during operation during operation check (D), it is first determined whether it is before or after the second humidity detection point.
(F). Then, the counting of the T ₁ time is performed up to the second humidity detection point, and after the humidity detection, the countdown of the KT ₁ time (additional heating time) is performed.

Explaining the control before humidity detection, it is first checked whether the humidity change exceeds the first threshold value Δh (G).

When this condition is satisfied, the high frequency output starts to be intermittent (H). The detection time T ₁ is counted regardless of the condition of the G term (I).

The additional heating time KT ₁ is calculated based on this T ₁ time, and the content is updated (K).

The additional heating control after the second detection point is the additional heating time KT
It is executed by counting down ₁ (L) and supplying power until its content becomes zero (M). A configuration in which the additional heating time is counted up and compared with the KT ₁ time calculated in the K term, and if they match is determined to be the end of heating can be considered. During additional heating, high frequency output is intermittent (J).

When the KT ₁ time ends, an end process such as notification by a buzzer is performed (N), and the process returns to START.

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

(1) During reheating of large foods and thawing of frozen foods, steam released due to local overheating cannot be detected, and the entire food is heated sufficiently to leave prematurely cut or unthawed parts. Good cooking is possible without exception.

(2) At low output, the locally overheated part is eliminated by heat conduction, and a finish with less uneven heating can be obtained.

(3) Rough heating is performed at a high output all at once until steam locally begins to be emitted, so cooking is completed in a much shorter time than when heating at a low output from the beginning.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a heating pattern of a high-frequency heating apparatus showing an embodiment of the present invention, FIG. 2 is a perspective view thereof, FIG. 3 is a block diagram showing the same structure, and FIG. 4 is a control unit thereof. It is a flowchart. 2 ... Automatic cooking key, 3 ... Control part, 6 ... Juan, 7
...... High frequency generating means, 9 ...... Sensor, 10 ...... Heating chamber,
12 ... Object to be heated.

Claims (1)

[Claims] 1. A heating chamber in which an object to be heated is placed, a high-frequency generator connected to the heating chamber, a controller for controlling power supply to the high-frequency generator, and an object to be heated in the controller. A sensor for detecting at least water vapor that is generated, wherein the control unit detects at least water vapor from the object to be heated using the sensor, and switches a high-frequency output based on the detected amount; After switching the high-frequency output, the sensor further detects at least a further increase in the amount of water vapor from the object to be heated, monitors the second detection point at which the amount reaches a certain value, and reaches the second detection point. A high-frequency heating device configured to control the end of heating on the basis of the time required for the heating.