JPS6237295B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention detects food by detecting the temperature of the food by changing the terminal voltage of a gas sensor whose resistance value changes with time depending on the concentration of exhaust gas consisting of evaporated components such as odors, smoke, and smoke coming from the food being heated. The present invention relates to a microwave oven that automatically determines the completion of cooking food by determining the type of food.

Conventionally, when heating the food using microwaves and then energizing the heater to perform so-called grill heating, when the heater is energized, the amount of burnt food does not vary greatly depending on the amount of food, so after heating for a certain period of time (T _H ), Some systems employ an additional heat method in which the additional heat time is set in proportion to the time required for microwave heating, but this method has the following drawbacks.

When heated with a heater for a certain period of time (T _H ), the degree of charring varies depending on the weight of the food, and foods with a large weight tend to be poorly charred and foods with a small weight tend to be charred well.

The additional heat method is a method in which heater heating is further added for a certain period of time (T _H ), so there is an inconvenience that heater power is required for the additional heat.

The present invention has been made in view of the above-mentioned points, and is designed so that the heavier the food, the closer the heater is to the food during grill heating.

The present invention provides a measuring means for measuring the time required for microwave heating from the start of heating until a gas sensor detects that the concentration of exhaust gas emitted from the food being heated reaches a set value; Automatically changes the position of the heater during grill heating according to the measured time required for microwave heating by changing the position of the heater closer to the food if the time required for microwave heating is longer, and further away if it is shorter. The heater position setting means is configured to set the heater position.

Hereinafter, one embodiment of the present invention will be described based on the drawings.

Fig. 1 is an electric circuit diagram of a microwave oven showing an embodiment of the present invention, Fig. 2 is an explanatory diagram showing the position of the heater when heating a grill in a microwave oven, and Fig. 3 is a general diagram of a gas sensor. Output characteristic diagram FIG. 4 is an output characteristic diagram of a gas sensor showing the operation of the embodiment of the present invention.

In the figure, 1 is a keyboard of an operation panel of a microwave oven, on which a microwave heating key 2, a grill heating key 3, etc. are arranged. 4 is a gas sensor that is disposed at the exhaust port of the oven (not shown) and whose resistance value changes depending on the concentration of exhaust gas consisting of evaporative components such as odors, smoke, and smoke from the food being heated; It is connected to a DC power supply Vc via a load resistor 5. The outputs of the microwave heating key 2 and the grill heating key 3 and the output of the gas sensor 4 connected via the A/D converter 6 are connected to an interface 7. 8 is ROM,
It is a microcomputer consisting of RAM, CPU, etc., and is connected to the above-mentioned interface 7, and stores heating cooking sequences, measurement data, etc. 9,10,
Reference numerals 11 and 12 are NPN transistors connected to the interface 7, and on the collector side, there is a forward rotation relay 15 that rotates the motor 14 that drives the heater 13 up and down, and a reverse rotation relay 1 that rotates the motor 14 in the reverse direction.
6. A heater relay 17 that controls energization to the heater 13 and a microwave relay 19 that controls energization to the microwave heating device 18 are connected. 2
1, 22, and 23 are relay contacts of the forward rotation relay 15, reverse rotation relay 16, heater relay 17, and microwave relay 19, respectively. Note that 24 is food placed on a wire mesh 26 placed on the turntable 25.

Next, the operation of the microwave oven according to the embodiment of the present invention having the above configuration will be explained.

First, to briefly explain the general output characteristics of a gas sensor with reference to FIG.
The terminal voltage is input to the microcomputer 8 via the A/D converter 6 and the interface 7, and the ratio of the terminal voltage to time is calculated, and the type of food being heated is determined and the microwave heating suitable for the food is determined. Set the detection level Vs of the gas sensor 4 as follows. When the exhaust gas concentration level of the food 24 being heated reaches Vs, the microwave heating for time T1 ends. At the same time, electricity is started to be applied to the heater 13, and the motor 14, which moves the heater 13 to an appropriate position relative to the food 24, is driven for a time T _M , and when the heating time T ₂ set according to the type of food has elapsed. Grill heating by the heater 13 is completed.

By the way, FIG. 4 shows the output characteristics of the gas sensor 4 when the same food but different weights are used, for example, when one fish, two fish, and three fish are heated on the grill. For example, l ₁ above shows the output characteristic curve when there is one fish, l ₂ shows the output characteristic curve when there are two fish, and l ₃ shows the output characteristic curve when there are three fish. There is. First, the microcomputer 8 measures the time it takes to reach the microwave heating cooking finish level Vs, and the microcomputer 8 performs calculations and judgments according to these times T _1S , T _1M , and T _1L . Time for energizing the motor 13 that lowers the heater 12 stored in the ROM T _M
Select _S , T _MM and T _ML , respectively. Above time
T _1S , T _1M , and T _1L correspond to the weight of the food, and time T _1S is time T _MS , time T _1M is time T _MM ,
Time T _1L corresponds to time T _ML . That is,
The larger the load, that is, the weight of the food 24, the longer the energization time T _ML to the motor 13 becomes, so the descending distance of the heater 12 becomes the longest, and grill heating can be performed while the food 23 is close.
In addition, when the weight of the food 24 is small and when heating only one fish as shown in FIG _.
If this is set, the descending distance of the heater 12 will be shortened, the distance between the food 24 and the heater 12 will be appropriate, and the heating state will be optimal.

Incidentally, the heating time of the heater 12 is a certain time T _H
shall be. In this way, grill heating is performed by fixing the heating time to the heater 12 and controlling the distance between the food and the heater to be at the most appropriate position according to the microwave heating time.

As explained above, the present invention is capable of detecting food by detecting food by changing the terminal voltage of a gas sensor whose resistance value changes with time depending on the concentration of exhaust gas consisting of evaporated components such as odors, smoke, and smoke coming out of the food being heated. In a microwave oven that automatically determines when food is finished cooking by determining the type of food, microwave heating starts from the start of heating until a gas sensor detects that the concentration of exhaust gas emitted from the food being heated reaches a set value. A measuring means for measuring the time required for heating the food, and a position of the heater during grill heating according to the time required for microwave heating measured by the measuring means, if the time required for microwave heating the food is longer. Since it is equipped with a heater position setting means that automatically sets the position of the heater by changing the position of the heater by changing the position of the heater by changing the position of the heater by changing the position of the heater by changing the position of the heater by changing the position of the heater by changing the position of the heater by changing the position of the heater by changing the position of the heater by changing the position of the heater by changing the position of the heater by changing the position of the heater by changing the position of the heater by changing the position of the heater by changing the position of the heater by changing the position of the heater by changing the position of the heater, if the weight of the food is different, it is possible to uniformly heat the grill even if the weight of the food is different. Since the time for which the heater is energized is shorter than that in the conventional method, power consumption can be reduced, and the finish of grill heating, which is heated by the heater after microwave heating, can be controlled with high precision.

[Brief explanation of the drawing]

Fig. 1 is an electric circuit diagram of a microwave oven showing an embodiment of the present invention, Fig. 2 is an explanatory diagram showing the position of the heater when heating a grill in a microwave oven, Fig. 3 is a general output characteristic diagram of a gas sensor, FIG. 4 is an output characteristic diagram of a gas sensor showing the operation of the embodiment of the present invention. 2...Microwave heating key, 3...Grill heating key, 4
...Gas sensor, 13...Heater, 14...Motor,
17...Microwave heating device.

Claims (1)

[Claims] 1. Automatic cooking of food by determining the type of food based on the time change in the terminal voltage of a gas sensor whose resistance value changes depending on the concentration of exhaust gas consisting of evaporated components such as odors, smoke, and fumes emitted from the food being heated. A measuring means for measuring the time required for microwave heating from the start of heating until a gas sensor detects that the concentration of exhaust gas emitted from the food being heated reaches a set value in a microwave oven used to judge when the food is finished. Depending on the time required for microwave heating measured by the measuring means, the position of the heater during grill heating is changed so that it is closer to the food if the time required for microwave heating is longer and farther away if it is shorter. A microwave oven comprising heater position setting means for automatically setting the position of the heater.