JPS58200936A - Electronic range - Google Patents

Abstract

PURPOSE:To contrive the adequateness of heating of the titled device by a method wherein a sensor which detects the food humidity changing or the gas concentration caused by the dielectric heating is arranged near by an electric heater. CONSTITUTION:When a food 2 is dielectrically heated by the high-frequency electromagnetic wave generated by a magnetron 4, steam is generated from said food 2, said steam is discharged after introduced to a duct A'. At this time, a sensor 5 detects the humidity. Meanwhile, when a heater 10 is electrified and heated for the scorch finish cooking, said sensor 5 is heated up to higher temperature than about 400 deg.C, the useless substance attached to said sensor 5 is burnt out, then said sensor is refreshed. Accordingly, the operation accuracy of said sensor 5 is improved, the humidity detecting accuracy is also improved during the dielectric heating. In this case, the heat of said heater 10 is reflected by a reflector 11, the refreshing efficiency is improved. By such constitution, the humidity detecting accuracy is improved, the adequate heating can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a microwave oven, and its purpose is to detect the cooking state of food and heat it to an appropriate 1F.

Generally, the heating time for food is twice the initial temperature of this food fI4
．． It is determined by various quantities such as specific heat and absorbed energy. However, in conventional microwave ovens, the heating time is determined based on the type and amount of food to be dielectrically heated.

Therefore, in this case, among the various quantities that contribute to determining the heating time, the specific heat of the food and the initial temperature of the food are not particularly taken into account, and cooking errors may occur with such heating time settings. there were. In recent years, in order to solve the problems of conventional heating time setting, devices have been put into practical use that determine the dielectric heating time of food by detecting the humidity and gas concentration emitted from the food due to dielectric heating, and have attracted attention. ing. In this device, a heating element is provided around the sensor to refresh the sensor from dirt and the like, and after the sensor is refreshed by this heating element, the high-frequency oscillator is energized.

However, in this method, since the heating element for the freshco described in (-) is separately provided, there is a problem in that extra power is consumed for the purpose of generating heat.

Therefore, the technical object of the present invention is to enable sensor glue refreshing even without the above-mentioned conventional heating element.

The technical means of the present invention to solve this technical problem is to provide the above-mentioned sensor near the heater that heats the food! According to this technical means, each time the food is heated with the heater (e.g. browning the surface of the food), the sensor is sufficiently refreshed with a part of the heat emitted by the heater. With this sensor, humidity or gas concentration can be detected accurately, and as a result, optimal dielectric heating control for heated foods can be performed.

Furthermore, since there is no need to separately provide a heating element for refreshing, the configuration of a part of the sensor is simplified, and since the power consumption of the heating element is eliminated, the power consumption is reduced accordingly, resulting in energy savings. An embodiment of the present invention will be described below with reference to the accompanying drawings.

In FIG. 1, 1 is the main body of the microwave oven, 2 is food provided in the heating chamber A, and 3 is a blower fan.

4 is a magnetron used as an example of a high frequency oscillator, 6
is a humidity detection sensor made of metal oxide, and is installed inside the exhaust duct A/ from the heating chamber A. Also, 6
is a heating element that heats the atmosphere near the sensor 6, and closes the switch S to turn on electricity, but it is not necessarily necessary. 7 is a humidity amplifier, 8 is a cooking state detection circuit, and 9 is a control circuit for the heating element 6. 1o is a heater (for example, a sheathed heater) provided in the F part of the heating chamber A, and its energized part is provided in the exhaust duct A', and is connected to a power source within this duct A', although not shown. . In this configuration food 2
into heating chamber A and press the cooking button (not shown). (In this case, it is assumed that the switch S is open and the heating element 6 is not energized, and that the sensor 5 has been refreshed by the previous energization of the heater 10. This refresh will be described in detail later.) Then, the magnetron 4 energized, the magnetron 4 with
The food 2 is dielectrically heated by high-frequency electromagnetic waves radiated into the heating chamber A from the antenna 4a, and water vapor is generated from the food 2 due to this dielectric heating.

This water vapor is sent from the fan 3, heats up the magnetron 4 after cooling it, and enters the heating chamber A with cooling hot air (arrow F).
According to the arrow F', the air is discharged to the outside of the main body 1 through the exhaust duct A/.

Humidity is detected within this exhaust duct A/ by a sensor 6.

Figure 2 shows the sensor 5 in the state explained in Figure 1.
In the relative abundance graph detected by To-T5, time is H
0 to H5 represent the humidity at each time. If the time when the cooking button was pressed and the humidity at that time are To and Ho, then the cooling hot air from Magnetoon 4 flows into heating chamber A, and on the other hand, no water vapor has yet come out from food 2, so the relative humidity is It decreases like the M line. As electricity continues to be applied to the diversion magnetron 4 and heating continues, the cooling air volume of the magnetron 4 becomes more influential than the increase in water vapor generated from the food 2, and as a result, the relative humidity gradually decreases. Descend. Then, the point at which water vapor generation from food 2 increases and the humidity starts to rise is T3. At H3, the cooking state sensing circuit 8 of FIG. 1 stores the relative humidity at this point. Cooking ends at T4°H4 when a change in relative humidity greater than the preset relative humidity is detected (magnetron 4
Depending on the food item 2, either turn off the power to the
Constant K for the time from 2 to T4 (varies depending on food 2)
The cooking is completed by further dielectric heating for the time K (T4-T2). In this embodiment, the operations described in 1- below are performed.

Next, when power is applied to the heater 10 to brown the surface of the food 2, the surface of the food 2 is browned due to the heat emitted from the heater 1o, and at the same time, the heat generated by the heater 10 in the exhaust guide A' causes the sensor to be detected. 6 is heated to a temperature of 400°C or higher, and the waste matter attached to the sensor 6 is burnt out.
Refreshing is performed, and therefore accurate humidity detection is performed by the sensor 6 during the dielectric heating.

In this case, sensor 5 is opposite to heater 10.
A reflecting plate 11 having a hemispherical shape and a small number of holes is provided on the 1 side so as to cover the sensor 6 and the heating element 6, so that the heat from the heater 10 is reflected by the reflecting plate 11 and efficiently transmitted to the sensor 6. , refreshing can be performed reliably.

Furthermore, by providing the reflective plate 11, this reflective plate 11
Even though the reflecting plate 11 is provided with holes, airflow stagnates inside the reflecting plate 11, making it easier for the sensor 6 to detect humidity, and making control difficult from the point of view.

Note that the opening edge of this reflecting plate 11 is positioned to open downward in the lateral direction of the sensor 5, and the inner surface is also semispherical, so even if condensation such as water vapor occurs on this inner surface, it will not occur. Since it does not hit the sensor 5 along the inner surface and falls downward, it does not interfere with the humidity detection by the sensor 6.

Now, in the explanation in 1-1 above, we have talked about the case where the heater 1o is used occasionally, that is, the case where the sensor 5 is refreshed by the heat of the heater 1o, but depending on the household, Some households rarely use the heater 10, and in this case, the sensor 5 cannot be refreshed by the heater 1o, so the switch S is closed before pressing the cooking button. Then,
The control circuit 9 of the heating element 6 works together with the magnetron 4 and the fan 3, which causes the heating element 6 to generate heat and remove dust attached to the sensor 5 and water vapor (absorbed moisture) from the previous use, thereby refreshing the sensor. be exposed. When this is completed (in this embodiment, the surface of the sensor 6 is 40
When the temperature reaches 0° C. or higher, the power to the heating element 10 is cut off. Thereafter, the food 2 emits water vapor as in the case when the heating element 6 is not used, and the relative humidity at that time is measured by the sensor 6.
The cooking state sensing circuit 8 detects the difference in relative humidity from the time at the start of cooking, and controls the magnetron 4 based on this.

Further, in FIG. 2, in this case, as shown by the N line, the relative humidity reaches its lowest at T1°Hl at the end of refreshing by the heating element 6, that is, when the surface of the sensor 5 reaches 400°C. Then, when the current to the heating element 6 is cut off, the sensor 6 is cooled and the relative humidity increases, and from around the 12th section it becomes similar to the M line.

Although the sensor 5 detects the humidity in FIGS. 1 and 2, the sensor 5 may also detect the gas concentration based on the heating of the food.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a microwave oven according to an embodiment of the present invention, and FIG. 2 is a characteristic diagram thereof.

Claims (1)

[Claims] (]) A heating chamber, a high-frequency oscillator that dielectrically heats the food in the heating chamber, a sensor that detects humidity or gas concentration that changes due to the dielectric heating of the food by the high-frequency oscillator, and the food Equipped with a heater that heats the
A microwave oven with the above sensor installed near the heater. (2) The microwave oven according to claim 1, in which a reflector is provided on the opposite side of the sensor from the heater.