JPS5840432A - Microwave range - Google Patents

Abstract

PURPOSE:To carry out favourable finish control, by a method wherein a kind of preparation is fractionalized further due to difference of time variation peculiarity of output voltage of a gas sensor, and an additional heat constant is set up for every fractionalized kind so that scarcity of heating time is compensated. CONSTITUTION:The kind of food in a heating chamber is discriminated coarsely through a time variation rate of an output signal of a gas sensor, and a detection level for completion of heating by the gas sensor is set up according to the kind. As for food whose above time variation rate is discriminated as the smallest one, a time variation of an output level of the gas sensor after the output of the gas sensor has arrived at a fixed detection level is discriminated as to whether it is larger or smaller by comparing it with the time variation fixed beforehand, one of different additional heat constants set up beforehand is selected so that it is heated additionally for time which has been given by multiplying time required for arriving at the detection level for completion of heating by a selected additional heating constant.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a microwave oven, and more specifically, to a microwave oven that determines the type of food based on a time change in the terminal voltage of a gas sensor and automatically determines the finishing of the food.

Conventionally, a microwave oven that uses a sensor to automatically determine the cooking finish of food is equipped with a plurality of keys corresponding to the type of ilIfM, and the cooking finish temperature is preset for each key.

In response, the present inventor has eliminated the need for setting keys for each type of cooking by determining the type of food based on the time change in the terminal voltage of the gas sensor and calculating and setting the finished cooking temperature for that food. Invented a microwave oven with an ``automatic heating'' method. The present invention was invented in connection with the invention of this "automatic heating" type microwave oven.

First, we will explain the principle of the "automatic heating" method.

FIG. 1 shows how the terminal voltage V5 of the gas sensor 7 changes over time depending on the type of food being cooked. When the terminal voltage of the sensor after a time TI has elapsed from the start of heating is vTl, and the terminal voltage of the sensor after a time Ts has elapsed as Vtl, and this ratio is calculated, this value shows a significant difference depending on the type of food. For example, 'rt=ao seconds, T! - At 40 seconds, 0.9 or less for hot water, 0.9 for side dishes and rice bowls.
-0.95, and the preparation wrapped in cling film has a value of 0.95-1.0. Like this! ] The type of food is determined from the size of T1 1, and the VG detection device for which heating should be stopped VH5I Vns
, Vss can be set.

However, in conventional microwave ovens that are equipped with multiple cooking keys for each type of cooking, for example, the "preparation" of food is usually divided into "leaf vegetables" and "root vegetables," and "preparation 1 (leaf vegetables)" is divided into "leaf vegetables" and "root vegetables." ” and [preparation] were dealing with ``preparation''. The reason for this is that leafy vegetables such as spinach, Chinese cabbage, and cabbage are sufficiently boiled and softened when the heating temperature is close to 100°C, and the preparation is complete. ℃
Even when it gets close, the inside is still not soft, and if you stop heating at this point, the inside will be hard and uncooked. FIG. 2 shows this by the time characteristics of the gas sensor one terminal voltage Va.

FIG. 3 shows actual measurement data of the temporal change in the voltage VG at one terminal of the gas sensor when both ``root vegetables'' and ``leaf vegetables'' are wrapped in plastic wrap and heated in a microwave oven, as is usually done. Based on this data, the temperature inside the wrap after heating starts is 100.
Both show similar characteristic changes until the temperature rises to around 100°C (100°C), when the wrap ruptures due to strong vapor pressure, gas and moisture escape to the outside, and the sensor voltage suddenly changes. It became clear that there was a significant difference in the rate of change between "leaf vegetables" and "root vegetables."
Because they are fresher than root vegetables, they have a high moisture content and a large surface area, so the level changes rapidly and the amount of change is large. It has an epidermis, a relatively small surface area, and a low water content, so the rate of change in level is slow and the amount of change is small. In addition, in FIG. 3, the mark 0 indicates the optimum point for stopping heating.

The present invention has been completed based on the above-mentioned research, and is an automatic finishing microwave oven with one cooking key that automatically controls the finishing of food using sensing elements such as a gas sensor or a gas sensor and a thermistor. After the gas sensor reaches a predetermined detection level (Vsl), it is determined whether the temporal change in the output level of the gas sensor is larger or smaller than a predetermined temporal change, and a preset difference is determined. After the output signal of the gas sensor reaches the heating end detection level, the selected additional heat constant It is characterized by being configured to add heat for a time multiplied by .

As is clear from the comparison between Figure 1 and Figure 2, the preparation of "leaf vegetables" and "root vegetables" are both "preparation" in Figure 1.
belongs to the type of Therefore, time after heating starts! After the snow has passed and it is determined that it belongs to the "preparation" category, and the detection level of the gas sensor that should output a heating completion signal is set accordingly, the characteristics of leafy vegetables and root vegetables are determined as shown in Figure 2. The curve branches out and reaches the first detection level (VSt), and then due to the temporal change in the output level of the gas sensor, "
Leaf vegetables” and “root vegetables” are distinguished, and the additional heat constant (Nic)
is determined.

Embodiments of the present invention will be described below based on the drawings. FIG. 4 shows a front view of the appearance of an embodiment of the present invention. On the operation panel 1, an "auto heating" key 2 and a heating key 6 are arranged. ing. Note that it is also possible to combine keys 2 and 3 into one.

A calculation section within the CPU calculates the ratio Th between the two.

VTI Then, as explained with reference to FIG. 1, the type of food is determined based on the size of the fleas, and the optimal finished VTI levels VH5, VDS, vss are determined.

For those whose next + value is determined to be 0.95 to 1.0, as shown in Fig. 7, until the terminal voltage vG of the gas sensor reaches the preset first detection level Vsl Measure the required time Tyl or Ticl, store the value in RAM, and further calculate the time TY! from the start of heating until the preset second detection level vS is reached. Alternatively, Txl is measured and also stored in RAM. Therefore, the CPU reads out the two times stored in the RAM and calculates the difference ΔT between them.

△T - (TYx TYl) or (Tg -TK
I) If this difference △T is larger or smaller than a predetermined value △Tx that is written in the ROM with the program, and it is determined that the difference is ``leaf vegetables'', for example,
For example, if the additional heat constant NK is set to 0.1 and the vegetable is determined to be a root vegetable, the additional heat constant NK is set to NK-1, for example.

According to experiments, when Vat * Vat is set appropriately, ΔT-2 to 5 seconds for "leaf vegetables" and ΔT-30 to 50 seconds for "root vegetables", and setting it to ΔTic-17 seconds ensures F leafy vegetables J and "root vegetables" were distinguished. Based on the setting of such an additional heat constant Nx, food that is determined to be "leafy vegetables" has a gas sensor voltage Vc of level VS,
After reaching , heating is stopped after a slight additional heating of (0, I
), then heating is stopped.

As a modified embodiment of the present invention, the time difference ΔT of the above embodiment is
Instead, calculate the time rate of change of the sensor output voltage,
The additional thermal constant Nx may be determined by distinguishing its magnitude.

According to the present invention, since the computer selects one "auto heating" key and controls the product to achieve the optimum finish, the operation panel is simplified, and the user's judgment is omitted, making it easier to use. In addition, the types of "preparation" are further subdivided based on the differences in the temporal change characteristics of the output voltage of the gas sensor.
Since this method compensates for the lack of heating time by setting an additional heat constant Nx for each subdivided type, it is possible to better control the finish of the food.

[Brief explanation of the drawing]

FIG. 1 is a characteristic diagram explaining the principle of food types in the present invention, FIGS. 2 and 3 are characteristic diagrams explaining the problem to be solved by the present invention, and FIG. 4 is an external front view of an embodiment of the present invention. FIG. 5 is a longitudinal sectional view of FIG. 4, and FIG. 6 is a circuit diagram of an embodiment of the present invention. FIGS. 7 and 8 are characteristic diagrams illustrating the operation of the embodiment of the present invention. 1...Operation panel, 2...Automatic heating key, 7...Gas sensor, 9...Magneto four, 12...A -D converter, 14...interface, 15...microcomputer, Vsl...
...Detection level.

Claims (1)

[Claims] A switching means for controlling the drive power of the microwave generator, a gas sensor provided in the exhaust passage of the heating chamber, a heating instruction switch commonly used for different types of food, and an output signal of the gas sensor. It also has a microcomputer that issues a heating stop command to the drive power source and heater of the microwave generator according to a built-in program, and roughly determines the type of food in the heating chamber based on the temporal rate of change of the output signal of the gas sensor. Then, the heating end detection level by the gas sensor is set according to the type of food, and the output of the gas sensor is set to a predetermined detection repeat # (V, 1) It is determined whether the temporal change in the output level of the gas sensor after reaching 1) is larger or smaller than a predetermined temporal change, and a different preset additional heat constant & (NK) is determined. Select one, and after the output signal of the gas sensor reaches the heating end detection level,
A microwave oven configured to provide additional heat for a time equal to the time required to reach the heating end detection level multiplied by the selected additional heat constant.