JPH06249447A - High-requency heating apparatus and bread detection method using the same - Google Patents

Abstract

PURPOSE:To automatically perform suitable cooking for foodstuffs by measuring voltage strengths of microwaves radiated into a heating chamber. CONSTITUTION:After foodstuffs are set on a table 2 in a heating chamber 1, microwaves are generated in the heating chamber 1 by a microwave generating means 5. In this case, leakage of microwaves is detected at regular intervals by a microwave detecting means 7, and a control means 8 compares the detected voltage with a preset threshold value of the detected voltage and determines a state of the food on the basis of changes with time in the detected voltages. Then, the control means 8 regulates a heating output stored in advance and sets a heating time on the basis of the determined result of the state of the food, and cooking is performed by a resistance heating means 3. Therefore, suitable cooking for the amount and state of the food in the heating chamber 1 can be automatically performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency heating apparatus, and more particularly to a high frequency heating apparatus equipped with a microwave generating device and a detecting device for a toaster range or the like and capable of detecting the condition of food.

[0002]

2. Description of the Related Art Conventionally, a high-frequency heating device is one in which food to be cooked is placed on a table arranged on the bottom surface of a heating chamber and heated by the action of microwaves introduced into the heating chamber. Is.

On the other hand, the toaster range is for heating and cooking with a heater mounted above or below a table on which bread is placed in a heating chamber. In some high-frequency heating devices and toaster ranges, the amount of food stored or the number of breads is measured by weight detection by a weight sensor to determine an appropriate cooking time and automatically operate.

[0004]

However, when baking bread in a high-frequency heating device, it is inconvenient to use it simply as a toaster, because heating the microwave alone causes the bread to become entangled.

Further, in the toaster, the difference in the initial temperature of the bread stored in the heating chamber is taken into consideration when the bread is frozen and the cooking time is determined only by determining the number of breads by weight detection. Because it is not done, cooking may not be successful. Furthermore, even if a humidity sensor that measures the humidity inside the heating chamber is attached to the toaster and the frozen state of the stored bread is determined, the moisture content of the bread itself is small, so the number of breads must be reliably determined. Is difficult, and automatic adjustment of cooking time is also difficult.

The present invention has been made in consideration of the above circumstances, and the amount of food in the heating chamber and the initial state of the food can be determined by measuring the voltage intensity of the microwave supplied into the heating chamber. An object of the present invention is to provide a high-frequency heating device that can be surely grasped and that enables appropriate automation of cooking according to the amount and state.

[0007]

FIG. 1 shows a block diagram of the configuration of the present invention. As shown in the figure, the present invention relates to a heating chamber 1 for storing food, a table 2 for placing food in the heating chamber, a resistance heating means 3 for heating food provided in the heating chamber, and resistance heating. Heating drive means 4 for controlling the operation of the means 3, microwave generation means 5 for supplying a microwave for food detection to the heating chamber, oscillation drive means 6 for controlling oscillation of the microwave generation means 5, and heating chamber Microwave detecting means 7 for detecting the microwave leaking through the opening of the top plate and outputting it as a voltage, and the heating driving means 4 for judging the state of the food in the heating chamber from the detected detection voltage of the microwave. The present invention provides a high-frequency heating device including a control means 8 for controlling the above.

Here, the table 2 on which the food is placed is preferably a rotary turntable which is usually used in a microwave oven in order to uniformly heat the food. The resistance heating means 3 preferably uses an infrared or nichrome wire heater to heat the bread or the like.

A magnetron is usually used as the microwave generator 5. Further, the heating drive means 4 and the oscillation drive means 6 include an electronic device including a semiconductor switch element and a relay that can turn on / off the heating or the oscillation or adjust the output of the heating or the oscillation according to a control signal from the control means 8. Composed of circuits.

The microwave detecting means 7 is usually composed of a linear receiving antenna for receiving microwaves and a detection circuit for detecting the waves received by the receiving antenna with direct current.

The control means 8 has a CPU (central control unit) as a center, a circuit for input / output conversion of analog signals and digital signals, and a procedure for determining the state of food using the input signals and controlling heating and the like. And a memory element and the like in which conditions of heating output and heating time corresponding to the food condition are stored.

[0012]

After the food is placed on the table in the heating chamber 1, microwaves are generated in the heating chamber by the microwave generating means 5 for a certain period of time. At this time, the microwave detection voltage leaked through the opening of the top plate in the heating chamber 1 is detected by the microwave detection means 7.

The microwave detection is performed a plurality of times at regular intervals, and the control means 8 compares the threshold value of the detection voltage set in advance with the detection voltage measured by the microwave detection means 7 and performs the measurement. The state of the stored food product is judged from the temporal changes in the detected plural detected voltages.
Next, the control means 8 adjusts the heating output and the heating time which are stored in advance based on the determination result of the food state, and causes the resistance heating means 3 to cook.

According to the present invention, the microwave is radiated into the heating chamber and the detection voltage of the microwave is measured before the heating by the resistance heating means 3 is performed as described above. It is possible to reliably grasp the amount of food and the initial state of the food, and it is possible to automate the appropriate cooking corresponding to the amount and the state.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on the embodiments shown in the drawings. The present invention is not limited to this. FIG. 2 shows a block diagram of an embodiment of the high frequency heating apparatus of the present invention.

In the figure, 21 is a food to be heated, 22 is a heating chamber for housing the food 21, 23 is a turntable provided at the bottom of the heating chamber for placing the food 21, and the turntable 23 is the heating chamber. The food 21 on the turntable 23 is heated uniformly by being rotated by a turntable motor 24 arranged outside.

An upper heater 25 is provided on a wall surface above the heating chamber 22, and a lower heater 26 is provided below the turntable 23.
To heat food. In addition, the top plate 27 of the heating chamber 22
The waveguide opening 2 facing the center of the turntable 23.
8 is opened, and a detection unit 30 to which a microwave sensor 29 for detecting microwaves leaking from the heating chamber is attached is provided on the outer surface side of the waveguide port 28 of the top plate 27.

The microwave sensor 29 is used for the food 2 being heated.
The microwaves, which are not absorbed by No. 1 but are standing inside the heating chamber 22 and leak from the waveguide port 28, are subjected to DC detection and a detection voltage corresponding to the detection level is output.

The amplification section 31 amplifies the detection voltage output from the microwave sensor 29 and gives the output to the control section 32. The control unit 32 determines the state of the stored food 21 on the basis of the detection voltage input from the amplification unit 31, and controls the magnetron drive unit 33 and the magnetron 35 that turn on and off the magnetron 35 that is a high-frequency radiation source. Cooling fan 36 for cooling, the heaters 25, 26
Heater drive unit 34 for turning on / off and adjusting the output,
And controls the operation of the turntable motor 34.

The control unit 32 is composed of a CPU, a memory in which means procedures (programs) such as heating operations are stored in advance, and circuit elements for converting input / output of analog signals such as detection voltage and digital signals. It

Further, the waveguide port 28 has a function of guiding the microwave standing inside the heating chamber 22 to the detection unit 30, and does not have to be a complete opening, and hot air to the detection unit and In order to prevent the invasion of dust, it is preferable to cover it with a cover made of a dielectric capable of transmitting microwaves.

The microwave sensor 29 comprises a microwave receiving antenna and a detection circuit for detecting the received wave of the receiving antenna by direct current. For example, as shown in FIG. 3, a copper foil pattern is formed on one surface of an aluminum substrate. By doing so, the antenna and the detection circuit are integrally configured.

FIGS. 3, 4, 5 and 6 are diagrams showing an embodiment of the circuit of the microwave sensor and the structure of the detecting portion.
FIG. 3 is a plan view of an embodiment of the microwave sensor 29 of the detection unit 30, in which the hatched portion shows a conductor pattern made of copper foil. The central portion of the aluminum plate is a circuit board having a predetermined inductivity, and one surface 5 of the circuit board is used.
A high frequency diode 5 having a linear antenna 511 formed in a pattern substantially in the center of 1a and having a cathode connected to a matching resistor 515 on one side in the line width direction of the antenna 511.
16 is patterned, and the anode of the high frequency diode 516 is connected to the ground surface 5 on the back surface through the through hole 518.
A high frequency detection circuit connected to 1b is arranged.

The other end of the antenna 511 in the line width direction is connected to a connecting line 517 at one end thereof, and a resistor R ₁ 514 for eliminating the influence of the connecting line 517 is formed in a pattern. A series circuit of resistors R ₂ 513 for taking out a voltage signal of the sensor output is patterned so as to be connected in parallel, a sensor output terminal is patterned on the other end side of the resistor R ₁ 514, and a capacitor 512 and a resistor R ₂ 513 are formed. One end of the through hole 5
An output circuit and an output line connected to the ground surface 51b on the rear surface via 19 are arranged.

A ground area 51c is provided on four sides of one surface 51a of the substrate, and through holes 53a, 53 for screwing the microwave sensor 51 to a support are provided at four corners.
a ... is provided.

FIG. 4 is an equivalent circuit diagram of the microwave sensor 29 shown in FIG. 3, in which the antenna 511 is connected to the cathode of a high frequency diode 516 via a matching resistor 515 and the anode is grounded.

Further the antenna 511 resistor R ₁ of 10KΩ is connected via a connection line 517, the other end of the resistor R ₁ is connected to the output terminal of the sensor output, between the antenna 511 and the resistor R ₁ is , A series circuit of a 1000 PF capacitor 512 and a 5.6 KΩ resistor R ₂ is connected in parallel, and one ends of the capacitor 512 and the resistor R ₂ are grounded.

FIG. 5 is an enlarged view of the vicinity of the detection unit 30. As shown in the drawing, on the outside of the position where the waveguide port 28 of the top plate 27 is formed,
A bracket 40 having a shallow rectangular parallelepiped box shape is fixed. The upper portion of the bracket 40 is opened over the entire surface, and a flange portion 41 formed by bending each edge outward is provided. The substrate of the microwave sensor 29 has the flange portion 41 with the surface on which the receiving antenna 51a is formed facing downward.
It is placed on the top of the bracket 40 and is fixed by screws with a plurality of setscrews 42, 42 ...
The detection unit 30 has a rectangular parallelepiped shape surrounded by the bottom and side surfaces of the microwave sensor 29 and the substrate of the microwave sensor 29.

FIG. 6 is an exploded perspective view of the detection unit 30 and the microwave sensor 29, as viewed from above the front part of the heating chamber 22. The waveguide port 28 has a predetermined angle (preferably 45 °) with respect to the direction of introduction of microwaves from the wall surface of the heating chamber provided with a magnetron shown by an arrow in the figure.
It is preferable that it is formed only with an inclination.

In the present invention, the amount of food stored in the heating chamber and the food stored in the frozen state are utilized by utilizing the microwave detection voltage detected by the microwave sensor 29 and the detection unit 30 having the above-mentioned configurations. Control unit 32
(Hereinafter referred to as a food condition detecting step).

Thereafter, the control unit 32, based on the detection information,
The food heating conditions are set, that is, the heating time and the heating output of the heater are adjusted according to a pre-installed program to automatically cook the food.

FIG. 7 shows an example of a temporal flow in which food is stored in the heating chamber, microwave heating is performed to detect the state of the food, and heating is performed with a heater for cooking. As shown in the figure, when food is stored in the heating chamber and an instruction to start cooking is given, first, heating by microwaves is performed in the food state detecting step. When the control unit 32 detects the cooking start instruction, it outputs an oscillation start signal to the magnetron oscillation drive unit 33, and the magnetron oscillation drive unit 33
Based on this signal, the magnetron 35 is activated and microwaves are radiated into the heating chamber.

In FIG. 7, for example, the output level 50
Microwave of 0 W, 13.5 seconds apart, 3 times in total, 1 each
Irradiate for 1.5 seconds. In this food condition detection step, the microwave radiation is not for heating the food but for detecting the condition such as the amount of the food. Therefore, the microwave is not radiated for a long time, and the microwave sensor 29 does not radiate the food. It suffices to radiate microwaves for a time and number of times sufficient to sufficiently detect the above condition.

The microwave sensor 29 detects the microwave leaking from the waveguide port 28 above the heating chamber and outputs a detection voltage. The control unit determines the detection voltage output through the amplification unit, selects the preset heating condition, adjusts the heating time and output in the subsequent food heating process, and stores it in advance. Cooking is performed by heating the heater automatically according to the procedure.

FIG. 8 shows an example of the detection average voltage output from the microwave sensor 29 when bread is used as food. In this example, as in FIG. 7, a microwave with an output of 500 W is radiated three times for 11.5 seconds in the food state detecting step. FIG. 8A shows a temporal change in the average detection voltage when only one piece of bread is stored in the heating chamber. FIG. 8B shows a temporal change of the detection average voltage when two breads are stored in the heating chamber.

In the figure, the average detection voltage is around 2.25 V when one pan is used, and the average detection voltage is around 1.5 V when two pans are used. According to the figure, the threshold value of the detection average voltage is, for example, 2V.
If is selected, the number of breads stored in the heating chamber can be reliably determined.

That is, as shown in FIG. 9A, when a value exceeding the threshold value 2V as the detection average voltage is detected the number of times of determination (here, three times), the control unit 32 sets one pan. It is determined that only those stored in the heating chamber. Then, in the food heating process, the control unit 32 selects the pre-stored heating time or the output level of the heater as a condition under which one piece of bread can be baked in an appropriate state, and the pre-stored condition is stored under the condition. Cook the bread according to the heating procedure given.

Specifically, cooking is performed by the heater driving unit 34 controlling the outputs of the heaters 25 and 26 in accordance with a signal relating to the heating time or the output level of the heater output from the control unit 32. Further, as shown in FIG. 9B, a value lower than the threshold value 2V is determined by the number of determinations (here, 3).
If it is detected, it is determined that the two breads are stored in the heating chamber, and the heating time is longer or the output level of the heater is higher than that in the case of FIG. 9B according to the heating condition stored in advance. Adjust to cook.

FIG. 9 shows a comparative example of the average detection voltage when one bread at room temperature and frozen is stored in the heating chamber. FIG. 9A shows the detection average voltage when one bread at room temperature is stored, which is stable at about 2.25V. Figure 9 (b)
Is the detection average voltage when one frozen bread is stored, but the value that was about 2.5 V at the beginning of storage shows a decreasing tendency over time. This means that the bread is heated by radiating microwaves, but "the initial value of the detection average voltage of frozen bread is higher than that of bread at room temperature, and there is a tendency for it to decrease due to heating by microwaves. By utilizing the property of “showing”, it is possible to determine whether the room temperature bread is stored or the frozen bread is stored.

For example, 2.3 V is stored in advance as the threshold value of the detection average voltage, the detection average voltage at the first time shows a value higher than 2.3 V, and at the time of the third measurement of the detection average voltage. When the detected average voltage lower than 2.3 V is detected, the control unit 32 determines that one freezing pan is stored in the heating chamber. Further, in the subsequent food heating process, the control unit 32 selects the heating time and the heater output level which are stored in advance as the cooking condition for one frozen bread and causes the cooking to be automatically performed according to the procedure stored in advance. .

The specific example of the configuration of the high frequency heating apparatus of the present invention and the example of the bread detecting method using the high frequency heating apparatus have been described above. The bread by measuring the detection voltage of the microwave as described above is described. The determination of the number of sheets and whether they are frozen or not can be applied to foods other than bread.

The threshold value of the detection voltage serving as the determination reference as shown in FIGS. 8 and 9 is preset for each food subject to experience, and the cooking conditions corresponding to the determination result are stored. By doing so, it is possible to automatically perform cooking suitable for the amount and condition of the food stored in the heating chamber.

By radiating microwaves to food such as bread for a certain period of time, the same effect as heating can be obtained, and in the case of bread, there is a problem in that bread is exposed when microwaves are radiated for a long time.

Therefore, in the case of cooking bread, the microwave radiation time should be as short as possible and the microwave output level should be low as long as the detection by the microwave sensor is possible in the food condition detecting step. desirable.

Therefore, in addition to the method of intermittently radiating the microwaves as shown in FIGS. 7 to 9, a method of continuously radiating the microwaves with the microwave output lowered, for example, from 500 W to 250 W may be used.

Further, in order to reduce the spread of the bread, after the bread is stored, the heater is heated for several seconds, and then the state of the stored bread is judged by carrying out the food state detection step by microwave heating. After that, the heater heating suitable for the state of the re-stored bread may be performed.

[0047]

According to the present invention, the amount of food in the heating chamber and the initial state of the food can be surely grasped by measuring the voltage intensity of the microwave radiated in the heating chamber. It is possible to automate appropriate cooking according to the condition.

[Brief description of drawings]

FIG. 1 is a configuration block diagram of the present invention.

FIG. 2 is a block diagram of a configuration in an embodiment of the present invention.

FIG. 3 is a plan view of an embodiment of the microwave sensor of the present invention.

FIG. 4 is an equivalent circuit diagram of the microwave sensor of the present invention.

FIG. 5 is an enlarged view of the vicinity of the microwave sensor and the detection unit in the embodiment of the present invention.

FIG. 6 is a perspective view showing an assembled state of the microwave sensor and the detection unit in the embodiment of the present invention.

FIG. 7 is an explanatory diagram of a food condition detecting step and a food heating step according to the present invention.

FIG. 8 is an explanatory diagram of a food condition detecting step when storing bread according to an embodiment of the present invention.

FIG. 9 is an explanatory diagram of a detection average voltage when a room temperature pan and a frozen pan according to an embodiment of the present invention are stored.

[Explanation of symbols]

 1 heating chamber 2 table 3 food heating means 4 heating drive means 5 microwave generation means 6 oscillation drive means 7 microwave detection means 8 control means 21 food (bread) 22 heating chamber 23 turntable 24 turntable motor 25 upper heater 26 lower part Heater 27 Top plate 28 Waveguide port 29 Microwave sensor 30 Detection part 31 Amplification part 32 Control part 33 Magnetron oscillation drive part 34 Heater drive part 35 Magnetron 36 Cooling fan

Claims (2)

[Claims] 1. A heating chamber for storing food, a table for placing the food in the heating chamber, a resistance heating means for heating the food provided in the heating chamber, and a heating drive means for controlling the operation of the resistance heating means. A microwave generating means for supplying a microwave for food detection to the heating chamber, an oscillation driving means for controlling the oscillation of the microwave generating means, and a microwave leaking through the opening of the top plate of the heating chamber. A high-frequency heating device comprising microwave detecting means for outputting a voltage as a voltage, and control means for determining the state of food in the heating chamber from the detected detection voltage of the microwave and controlling the heating driving means. 2. A microwave is radiated into the heating chamber by the microwave generation means 5 after a pan is put in the heating chamber, and the microwave detection voltage is measured a plurality of times by the microwave detection means 5 at regular intervals. Then, the control means 8
The number of breads is determined by comparing a preset threshold value with the measured plurality of detection voltages, and whether or not the bread is frozen is determined from the temporal change of the plurality of detection voltages. The bread detection method using the high-frequency heating device according to claim 1, wherein the determination is performed.