JPS5990387A - Electronic range - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a microwave oven, and more specifically, it is capable of not only determining the type of food and determining the appropriate cooking time, but also being able to distinguish the type of food and determine the appropriate cooking time. The present invention relates to a microwave oven that can appropriately heat and thaw frozen food by determining whether or not the food is frozen.

<Prior art> An electronic heating system with a so-called "automatic heating method" that has the function of determining the type of food and determining the appropriate cooking time accordingly, and therefore does not require individual heating command keys for each type of food. In microwave ovens, food type discrimination is performed using built-in food type discrimination sensors such as humidity sensors and gas sensors. These sensors detect the water vapor that evaporates from heated food and determine the type of food based on the differences in the water vapor evaporation characteristics of the food, so the temperature of the food must be several tens of degrees or higher for the sensor to activate. It is necessary for the generation of water vapor to reach a certain level.

Therefore, when trying to thaw frozen food using the conventional 1-automatic heating method microwave oven using such a sensor,
Even if the temperature of the food rises to several degrees Celsius and thawing is complete, a sensor that responds to the evaporation of water from the food will not be able to detect the completion of thawing. For this reason, even if a microwave oven has an ``automatic heating method,'' it is not possible to ``defrost'' frozen foods, and the microwave oven must be turned on manually after an appropriate heating time determined by the cook based on experience. If you don't cut it,
Even after thawing, the heating of the food continues until the cooking is completed. What's more, frozen foods are continuously heated using microwaves with the same power as when heating non-frozen foods.
The food is not thawed uniformly over the entire area, resulting in localized temperature differences and uneven thawing.

<Object of the invention> In addition to the functions of the conventional "automatic heating method" microwave oven, the present invention also has an automatic defrosting function for frozen foods.
In addition, frozen foods can be thawed uniformly. Its purpose is to provide a microwave oven with an "automatic heating method."

<Structure of the Invention> In order to achieve the above object, the microwave oven of the "automatic heating method" according to the present invention has an infrared sensor installed on the ceiling of the heating chamber in addition to the humidity sensor or gas sensor installed at the heating chamber exhaust port. It is being

<Description of Examples> Examples of the present invention will be described below based on the drawings. 1st
The figure is a sectional view showing an embodiment of the present invention, in which a magnetron 9 is mounted on the heating chamber ceiling, an infrared sensor 8 detects the temperature of food,
A thermistor 11 for temperature correction of the rotary chopper 10 and the infrared sensor 8 is provided, and a humidity sensor 7 is provided at the exhaust port 6 of the heating chamber. Note that numbers 5 and 12 indicate a fan and a food container, respectively. The infrared sensor 8 alternately receives infrared rays emitted from the food and infrared rays emitted from the light shielding part of the rotary chopper 11 reflecting the ambient temperature, and as shown in the graph shown in FIG. It outputs voltage according to the temperature of the food. FIG. 3 is a diagram showing the configuration of the electric circuit of this embodiment. The output of the infrared sensor 8 is input to the amplifier via the FET source follower, where it is amplified and smoothed, and then digitalized by the A-D converter 15. signaled. The outputs of the humidity sensor 7 and thermistor 11 are also sent to the A-D converter 13, respectively.
and 14, it is converted into a digital signal. These A-
The outputs of the D converters 13, 14 and 15 and the output from the heating command keyboard are input to the microcomputer 16 via the input/output interface 17. Power to the magnetron 9 is supplied from an AC power source via a power switch 20 and a relay switch 19, and the relay switch 19 is controlled by a control signal sent from a microcomputer 16 to a transistor 18 via an input/output interface 17. be done.

In addition, the heating command keyboard 1 has an "auto heating key" 2.
and a "heating key" 3, which are arranged on the front panel of the main body of the microwave oven next to the heating chamber, as shown in FIG.

The operation of this embodiment configured as described above will be explained based on the flowchart shown in FIG. 5 showing the program stored in the ROM of the microcomputer 16. First, put the food in the heating chamber and press the "Automatic heating key"
2 closes the relay switch 19, and the magnetron 9 starts heating the food by oscillating microwaves (step 51). Immediately thereafter, at time t=to, step 52
, the initial value vO of the output voltage of the infrared sensor 8 and the initial value UO of the output voltage of the humidity sensor 7 are stored in the RAM. Thereafter, as long as a change in the output voltage of the infrared sensor due to a rise in the temperature of the food can be detected, after the shortest possible time has elapsed, at time t=t1, the output voltage Vl of the infrared sensor and the output voltage Ul of the humidity sensor are detected, It is stored in RAM (step 53). In step 54 ■0 and vl
Determine the size relationship of. If the food is not a frozen food and the initial (1=10) temperature TO is higher than the ambient temperature Ta, as can be seen from the correspondence between the infrared sensor output voltage and the food temperature shown by the dotted line in Figure 2. , V
l -Vo >0, and in this case, of course, the food is determined to be a non-frozen food, and the process proceeds to step 61 to proceed to the normal "automatic heating" process.

Regardless of whether the food is a frozen food or not, the first (t
=to) when the temperature To is smaller than the ambient temperature Ta,
Moreover, if the temperature T1 at t=t1 is still smaller than Ta, as can be seen from the correspondence between the infrared sensor output voltage and the food temperature shown by the thin line in FIG.
Q<0. Note that even if TO<Ta, T1 is Ta
If it exceeds Vl-VO≧0, it is possible that
In the case of Vl-Vo, it goes without saying that step 54 proceeds to step 61, as in the case of TO>Ta. In any case, if it is determined in step 54 that v, -Vo≦0, the process proceeds to step 55, where the thermistor 11 detects the chopper temperature, that is, the ambient temperature Ta, and using this value, the microcomputer executes the step At 56, the output voltage Vr of the infrared sensor 8 corresponding to a temperature of -1°C is calculated.

Next, in step 57, Vl and Vr are compared and Vl-Vr≧
If it is 0, the food is determined to be a frozen food with a temperature of -1° C. or lower, and thereafter the food is thawed while the microwave output is intermittent in order to thaw the food uniformly (step 58). When the infrared sensor detects that the food has thawed and risen to a predetermined temperature (several degrees Celsius) (step 59), the microwave output is cut off (step 60), and the food thawing operation is completed. If it is determined in step 57 that Vl-Vr<0, the temperature of the food exceeds -1°C, and in this case, it is assumed that it is not a frozen food even if the temperature is below 0°C, and step 61
After that, normal "automatic heating cooking" is performed. In step 61, Ul and U2 stored in steps 52 and 53 are compared in the form of a ratio, and the output level of the humidity sensor at the time when heating should be stopped is set for each value range of U2/Ul. When the output voltage reaches the set level (step 62), the microwave output is cut off in step 60, and cooking is completed.

<Effects of the Invention> As is clear from the above description, according to the present invention, it is possible to obtain an "automatic heating" microwave oven that also has the function of thawing frozen foods to a predetermined thawing temperature without "heating" them.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing an embodiment of the present invention, Fig. 2 is an output characteristic diagram of an infrared sensor which is a component of this embodiment, Fig. 3 is an electric circuit diagram of this embodiment, and Fig. 4 is a diagram of the invention. FIG. 5, which is a front view of the embodiment, is a flowchart explaining the operation of this embodiment. 1 - Heating operation keyboard 2.3 - Heating operation key 4 - Heating chamber 5 - Fan 6 - Exhaust port 7 - Humidity sensor 8 - Infrared sensor 9 - Magnetron 10 - Chopper 11 - Thermistor 12 - Food 1 13, 14. 15-A-D converter 16--Microcomputer 17-Person output interface 18-) Transistor 19-Relay switch 20-Power switch 51-62-Flowchart steps Patent applicant
Sharp Agent Patent Attorney Nishi 1) New

Claims (1)

[Claims] A switching means that can switch the driving power source of the microwave generator between continuous energization state and intermittent open/close state, an infrared sensor installed on the ceiling of the heating chamber, and an infrared sensor installed in the exhaust passage of the heating chamber. A humidity/gas sensor, a heating instruction switch commonly used for different types of food, input signals from the infrared sensor and humidity/gas sensor, and a built-in program provide opening/closing control commands to the drive power source of the microwave generator. It has a microcomputer that emits the above humidity/gas sensor, determines the type of food in the heating chamber based on the temporal change rate of the output signal of the humidity/gas sensor, and sets the level of the humidity/gas sensor at which the heating stop command should be issued according to the type. , and is configured to determine whether the food in the heating chamber is a frozen food based on the output signal of the infrared sensor, and to issue a continuous opening/closing command to the drive power source of the microwave generator if the food is a frozen food. microwave oven.