JPH0791670A - High frequency heating appliance - Google Patents

Abstract

PURPOSE:To enable an automatic cooking to be carried out without having any irregular finished state in food by a method wherein a surface temperature of the food itself is measured regardless of an initial temperature of the food or presence or absence of a tray and a container for the food. CONSTITUTION:Since a stirring device 9 agitates a high frequency electro-magnetic wave and intermittently shields off radiation heat incident to a pyroelectric thermal sensing means 19 against a food, a signal corresponding to a temperature of the food is detected by the pyroelectric thermal sensing means 19. Further, since a control means 21 controls either a heating calorie or a heating time against the food according to an output from the pyroelectric thermal sensing means 19, a heating control corresponding to the temperature of the food is realized. In particular, the stirring device 9 acts as a chopper for the pyroelectric thermal sensing means 19, it can be realized easily and in less- expensive manner.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to automatic cooking, especially uniform heating, of food in a high frequency heating device.

[0002]

2. Description of the Related Art Conventionally, a high-frequency heating apparatus of this type has a turntable provided at the bottom of the heating chamber and a stirrer at the rear of the heating chamber, as shown in Japanese Patent Publication No. 60-25875, for example. It was intended to evenly heat the food.

As shown in FIG. 5, a heating chamber 1 is provided inside the main body, and a turntable 2 is placed at the bottom of the heating chamber 1 for rotating food items (not shown). On the rear surface, which is the side surface of the heating chamber 1, there is a power supply port 4 having an opening cover 3 made of glass or the like. The opening cover 3 is fixed by a packing 5 made of silicon rubber or the like. On the other hand, the high-frequency electromagnetic wave from the magnetron 6 which is a high-frequency oscillator passes through the waveguide 7, is stirred by the stirrer 9 rotating faster than the rotation speed of the turntable 2 by the stirrer motor 8, and enters the heating chamber 1 through the power supply port 4. Is irradiated. Stirrer 9
Has a stirring blade 10 to control the way of radiating high frequency electromagnetic waves from the power supply port 4. The grid-shaped hatching portion 11 of the turntable 2 is a diagram showing a heating portion from the power supply port 4, and is a diagram showing that the turntable 2 is heated uniformly by rotating. Reference numeral 12 is a door for loading and unloading food, and 13 is a control means for controlling the heating amount and heating time of the food by the magnetron 6.

FIG. 6 is a central sectional view of FIG. The turntable 2 is made of pottery or the like, and food (not shown)
Can be loaded. A turntable motor 14 for rotating the turntable 2 is arranged at the bottom of the turntable 2 and the turntable motor 14
The rotary shafts of are connected by a table 15 for rotating the turntable 2. Further, a weight sensor 16 is arranged at the bottom of the turntable motor 14 to detect the weight of the food placed on the turntable 2.

The control means 13 controls the heating amount and heating time of the food based on the output from the weight sensor 16. For example, the weight sensor 16 indicates that the weight of food is W
In the case of (g), the heating time ts (second) is ts = W * 0.5 + 200 (second) (Equation 1), and the heating amount P (W) is the elapsed time t from the start of heating.
According to (second), P = 600 (W) (when 0 ≦ t <0.5 * ts) (Equation 2) P = 300 (W) (when 0.5 * ts ≦ t <ts) (Equation 3) It realizes automatic cooking.

[0006]

However, in the above-mentioned conventional structure, if the initial temperature of the food before heating is already high, the food is overheated. In addition, since the weight of the plate or container on which the food is placed varies, the weight of the food itself cannot be known and there is a problem in that the quality of the food varies.

The present invention is intended to solve the above-mentioned problems. By accurately measuring the surface temperature of the food itself without being influenced by the initial temperature of the food, the presence or absence of a plate, a container, etc. An object is to provide a high-frequency heating device capable of cooking.

[0008]

In order to achieve the above object, a high frequency heating apparatus of the present invention comprises a heating chamber for heating food and a pyroelectric heat detection for detecting radiant heat radiated from the food in a non-contact manner. Means, a high-frequency oscillator that generates high-frequency electromagnetic waves in the heating chamber, and a radiant heat that is provided between the food and the pyroelectric heat detection means to stir the high-frequency electromagnetic waves in the heating chamber and to enter the pyroelectric heat detection means from the food. A stirrer for intermittently shutting off the food and a control means for controlling the heating amount or heating time of the food according to the output of the pyroelectric heat detecting means.

Alternatively, a heating chamber for heating food, a pyroelectric heat detecting means for detecting radiant heat radiated from the food in a non-contact manner, a high frequency oscillator for generating high frequency electromagnetic waves in the heating chamber, food and pyroelectric type A stirrer provided between the heat detecting means and the high-frequency electromagnetic wave in the heating chamber, and intermittently cutting off the radiant heat entering the pyroelectric heat detecting means from food, and a reference temperature detection for detecting the temperature of the stirrer. And means for controlling the heating amount or heating time of the food according to the outputs of the pyroelectric heat detecting means and the reference temperature detecting means.

[0010]

According to the present invention, since the stirrer stirs high-frequency electromagnetic waves in the heating chamber and radiant heat incident from the food to the pyroelectric heat detecting means is interrupted intermittently by the above-described structure, the pyroelectric heat detecting means detects the food temperature. A signal corresponding to is detected. This is because the stirrer also serves as a chopper function for the pyroelectric detection means to intermittently connect the infrared incident light. now,
If food temperature is T1 (K) and stirrer temperature is T2 (K) when the temperature sensitive field of the pyroelectric heat detecting means is occupied by food, the heat entering the pyroelectric heat detecting means is assumed. Voltage signal V that converts energy into electric energy and outputs
s (V) becomes Vs = R * (ε1 * σ * T1 ⁴ −ε2 * σ * T2 ⁴ ) (Equation 4) according to the Stefan-Boltzmann law. Here, R is output sensitivity, ε1 and ε2 are emissivity of food and stirrer, and σ is Stefan-Boltzmann constant. When both ε1 and ε2 are constant (for example, about 0.93), (Formula 4) is Vs = K1 * (T1 ⁴ −T2 ⁴ ) (Formula 5) K1 = R * ε1 * σ = R * ε2 * σ It can be transformed like (constant). Therefore, the food temperature T1 (K) is calculated from the output voltage Vs (V) from the pyroelectric heat detecting means and the stirrer temperature T2 (K). When the stirrer temperature hardly changes, (Equation 5) can be transformed into Vs = K1 * T1 ⁴ + K2 (Equation 6). K2 is a constant determined by K1. Therefore, the output voltage Vs (V) from the pyroelectric heat detecting means
From this, the food temperature T1 (K) is calculated.

Next, the control means controls the heating amount or heating time of the food according to the output of the pyroelectric heat detecting means,
Heating control according to the food temperature T1 (K) is realized.

Alternatively, a reference temperature detecting means for detecting the temperature of the stirrer is provided, and the control means controls the heating amount or heating time of the food according to the output of the pyroelectric heat detecting means and the reference temperature detecting means. Even when the stirrer temperature fluctuates, the food temperature T1 (K) is accurately measured, and heating control according to the food temperature T1 (K) is realized.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS.
Will be explained. The same components as those in the conventional example are designated by the same reference numerals. As shown in FIG. 1, a heating chamber 1 is provided inside the main body.
A turntable 2 is provided on the bottom of the heating chamber 1 for rotating food items (not shown). The rotation frequency of the turntable 2 is 0.1 Hz, for example. On the rear surface, which is the side surface of the heating chamber 1, there is a power supply port 18 having an opening cover 17 formed of a thin material such as silicon having a low loss dielectric and a high infrared transmittance. Opening cover 17
Are fixed by a packing 5 made of silicon rubber or the like. On the other hand, the high-frequency electromagnetic wave from the magnetron 6 which is a high-frequency oscillator passes through the waveguide 7 and is stirred by the stirrer 9 which is rotated by the stirrer motor 8 at a constant cycle (for example, 10 Hz) sufficiently faster than the rotation speed of the turntable 2.
The heating chamber 1 is irradiated with electricity from the power supply port 18. The stirrer 9 has a stirring blade 10 made of a material that is a low-loss dielectric and does not transmit infrared rays, and controls the way of radiating high-frequency electromagnetic waves from the power supply port 18. The surface of the stirring blade 10 is coated with a black body to increase the emissivity. Pyroelectric heat detection means 19 is provided further behind the stirrer 9. The stirring blade 10 has an opening ratio of 5 so as to intermittently block the radiant heat entering the pyroelectric heat detecting means 19 from food.
It has a hollow portion of 0%. That is, the stirrer 9 also serves as the chopper function for the pyroelectric heat detecting means 19 to interrupt the infrared incident light.

FIG. 2 shows the structure of the pyroelectric heat detecting means 19. The pyroelectric heat detecting means 19 is a lens cover 191, and a condenser lens 19 made of a material that transmits infrared rays, such as silicon.
2. Extracting the frequency component corresponding to the rotation frequency of the stirrer 9 from the output signal of the pyroelectric element 193 and the pyroelectric element 193, which has the thin film pyroelectric material and converts the radiant heat energy collected by the condenser lens 192 into electric energy. A band amplifier 194 that outputs a voltage Vs (V) proportional to the radiant heat energy incident on the condenser lens 192 by further amplification is provided. The pyroelectric heat detecting means 19 detects the surface temperature of the food (not shown) placed on the turntable 2 from diagonally above via the stirring blade 10 and the opening cover 17.

In FIG. 1, the grid-like hatching portion 20 of the turntable 2 is a view showing the temperature-sensitive field of view of the pyroelectric heat detecting means 19, and no matter where the food is placed by the rotation of the turntable 2, the food itself. It detects the temperature of. The dotted line represents the locus of infrared light that enters the 20 pyroelectric heat detecting means 19 from the temperature-sensitive field of view.

Reference numeral 12 is a door for entering and leaving food, 21
Is a control means for controlling the heating amount or heating time of the food by the magnetron 6 according to the output of the pyroelectric heat detecting means 19.

FIG. 3 is a central sectional view of FIG. The turntable 2 is made of pottery or the like so that food can be placed on it. At the bottom of the turntable 2, a turntable motor 1 for rotating the turntable 2
4, the rotary shaft of the turntable motor 14 is connected to a table 15 for rotating the turntable 2.

The control means 21 is the pyroelectric heat detection means 19
The heating time to the food is controlled based on the output from. The heating amount is constant, for example, 600 W. Pyroelectric heat detection means 1
When 9 outputs a voltage Vs (V) proportional to the incident heat energy, this output voltage Vs (V) changes as shown in FIG. 4 as the food is heated by the magnetron 6. The control means 21 completes the heating of the food when the detected output voltage Vs (V) reaches a predetermined value V0 (V).
In FIG. 4, the waveform vibrates in the turntable 2
This is because the food is repeatedly moved into and out of the temperature sensitive field due to the rotation of, and the dotted line A that plots the maximum value of the vibration waveform corresponds to the surface temperature of the food itself, and the dotted line that plots the minimum value of the vibration waveform. B corresponds to the surface temperature of the turntable 2 other than food. Naturally, food has a higher dielectric constant than the turntable 2 and is more likely to absorb high-frequency electromagnetic waves, so the temperature rises faster (the slope of the dotted line A is steeper than the slope of the dotted line B). Where food temperature T1
The relationship between (K) and the detected output voltage Vs (V) is based on (Equation 6).

By the way, the control method of the heating amount and the heating time by the control means 21 is not limited to this. For example, the heating time may be determined only from the initial voltage for one turn of the turntable 2 at the start of heating, or the amount of heating of the food by the magnetron 6 may be changed over time.
The output voltage Vs (V) may be converted to the food temperature T1 (K) and then controlled based on the food temperature T1 (K).

In the above structure, the stirrer 9 is used as the heating chamber 1.
Since the high frequency electromagnetic wave in the inside is agitated and the radiant heat entering the pyroelectric heat detecting means 19 from the food is interrupted intermittently, the pyroelectric heat detecting means 19 detects a signal corresponding to the food temperature. This is because the stirrer 9 also serves as the chopper function for the pyroelectric type detection means 19 to interrupt the infrared incident light. Further, the control means 21 is the pyroelectric heat detection means 1
Since the heating amount or heating time of the food is controlled according to the output of 9, heating control according to the food temperature is realized. In other words, even if the initial temperature, size, shape, and type of food are different, or if the plate or container is present, the finished temperature of the food is always controlled to be the same, so there is an effect that automatic cooking can be performed without variations in the finished product. In particular, since the stirrer 9 also functions as the chopper of the pyroelectric heat detecting means 19, it can be realized easily and at low cost.

The stirrer 9 changes the radiation pattern of the high-frequency electromagnetic waves from the power supply port 18 in various ways, so that the distribution of the high-frequency electromagnetic waves in the heating chamber 1 (the intensity of the radio waves) is made uniform, and further, the turntable 2 serves to produce food. By rotating the inside of the heating chamber 1, the uniformity of the food is further enhanced.

Next, a second embodiment of the present invention will be described. The difference from the first embodiment is that a reference temperature detecting means for detecting the temperature of the stirrer 9 is provided, and the control means 21.
The point is to control the heating amount or heating time of food according to the outputs of the pyroelectric heat detecting means 19 and the reference temperature detecting means. Here, the food temperature T1 (K) and the pyroelectric heat detection means 1
The relationship with the output voltage Vs (V) from 9 is in accordance with (Equation 5) above.

In the above structure, the food temperature T1 (K) is a value obtained from the output voltage Vs (V) from the pyroelectric heat detecting means 19 and the temperature T2 (K) parameter of the stirrer 19. That is, even when the temperature T2 (K) of the stirrer 19 fluctuates from 270K to 330K, the food temperature T1 (K) is accurately measured in consideration of the fluctuation, and the food temperature T1 (K) is measured. Heating control is realized. In other words, there is an effect that the automatic cooking can be performed with higher accuracy and without variations in the workmanship.

[0024]

As described above, the present invention has the following effects.

(1) Since the heating amount or heating time is controlled according to the food temperature without being influenced by the initial temperature of the food, the presence or absence of a plate, a container, etc., automatic cooking with no variation in the finished product can be performed. In particular, since the stirrer also has the function of the chopper of the pyroelectric heat detecting means, it can be realized easily and inexpensively.

(2) Since the food temperature is accurately measured even when the stirrer temperature fluctuates, there is an effect that automatic cooking can be performed with higher accuracy and without variations in the finished product.

[Brief description of drawings]

FIG. 1 is a horizontal sectional view of a high frequency heating apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of pyroelectric heat detection means in the embodiment.

FIG. 3 is a central cross-sectional view of the high-frequency heating device in the example.

FIG. 4 is a diagram for explaining the operation of the control means in the embodiment.

FIG. 5 is a horizontal sectional view of a conventional high-frequency heating device.

FIG. 6 is a central cross-sectional view of a conventional high frequency heating device.

[Explanation of symbols]

 1 Heating Chamber 6 Magnetron (High Frequency Oscillator) 9 Stirrer 19 Pyroelectric Heat Detection Means 21 Control Means

Claims (2)

[Claims] 1. A heating chamber for heating food, a pyroelectric heat detecting means for non-contact detection of radiant heat radiated from the food, a high frequency oscillator for generating high frequency electromagnetic waves in the heating chamber, and the food. A stirrer provided between the pyroelectric heat detecting means and the high frequency electromagnetic wave in the heating chamber to interrupt the radiant heat entering the pyroelectric heat detecting means intermittently from the food; A high-frequency heating device comprising: a control unit that controls the amount of heating or the heating time for the food according to the output of the mold heat detection unit. 2. A heating chamber for heating food, a pyroelectric heat detecting means for non-contact detection of radiant heat emitted from the food, a high frequency oscillator for generating high frequency electromagnetic waves in the heating chamber, and the food. A stirrer that is provided between the pyroelectric heat detection means and that stirs the high-frequency electromagnetic waves in the heating chamber and intermittently blocks radiant heat that enters the pyroelectric heat detection means from the food, and the stirrer. A high-frequency heating device comprising: a reference temperature detecting means for detecting a temperature; and a control means for controlling the heating amount or heating time of the food according to the outputs of the pyroelectric heat detecting means and the reference temperature detecting means.