JPS5847674Y2 - High frequency heating device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a method for detecting the state of a high-frequency heating device having a function of detecting the heating state of an object to be heated.

Conventionally, to measure the heating temperature of the heated object in the heating chamber,
The temperature was measured by inserting or contacting the temperature sensing part into the object to be heated and receiving the signal from the temperature sensing part through a metal lead-out line when supplying high-frequency output. It had the following drawbacks.

That is, when a high-frequency output is generated, a high-frequency current due to the high-frequency output flows through the metal lead wire, but this current is generated when the temperature of the heated object is detected.
For example, it has an adverse effect on minute electrical signals from a detection unit such as a thermistor, making it difficult to accurately detect temperature.

At the same time, the above-mentioned high-frequency current signal is guided outside the heating chamber through the take-out line, resulting in a strong high-frequency output leaking to the outside, which not only has a great impact on other communication equipment, but also poses a threat to the human body. , exposed to this leaked high frequency power,
There was a risk of harm.

Therefore, this invention eliminates the fatal drawbacks mentioned above. When high-frequency output is being supplied, the output of the detection signal heating chamber is short-circuited, thereby completely preventing leakage of high-frequency output. This provides a safer high-frequency heating device.

An embodiment of the present invention will be described below.

Figure 1 is a schematic diagram for explaining the principle of the present invention.
2 is a heating chamber wall, 2 is a heating chamber, 3 is a magnetron that generates high-frequency output, 4 is an object to be heated, 5 is a detection unit containing a temperature sensing element such as a thermistor that is in contact with or inserted into the object to be heated 4, 6 7 is a lead wire for leading the signal from the detection section 5 to the outside of the heating chamber 2, and 7 is a shield wire for protecting the detection section 5 and the lead wire 6 from high frequency output, one end of which is connected to the heating chamber wall 1. ing.

Reference numeral 8 denotes a changeover switch that switches between contacts 8a and 8b in response to intermittent oscillation of the high-frequency output, and the contact 8a is connected to, for example, an amplifier circuit necessary for controlling the high-frequency output, while the contact 8b is connected to the shield wire 7 which is at the same potential as the heating chamber wall 1.

Further, reference numeral 9 denotes an output changeover switch for intermittent oscillation of the high frequency output, and the intermittent operation of the output changeover switch 9 and the changeover switch 8 is performed by a motor 10.

Reference numeral 11 denotes an impedance for preventing rush current generated in the high voltage transformer 12 due to the intermittent operation of the output changeover switch 9.

Furthermore, 13 is a control relay for stopping the high frequency output when the temperature of the heated object 4 reaches a temperature corresponding to a set value.

Conventionally, as a method for measuring and detecting the heating state of the heated object 4,
It is considered appropriate to contact or insert a temperature sensing element such as a thermistor into the object to be heated 4, but when using these temperature sensing elements, it is necessary to transmit the signal of this temperature sensing element outside the heating chamber 2. It was necessary to transmit the information to the appropriate control device.

In addition, since electrical signals are generally the most appropriate signal to extract from the temperature sensing element, it is recommended to use a metallic conductive material to lead the signal from the temperature sensing element to the outside of the heating chamber 2. It had to be.

On the other hand, from the perspective of high frequency output, providing a metallic substance in the heating chamber 2 means that, for example, by transmitting the lead wire 6,
There have been undesirable phenomena such as the high frequency output leaking out of the heating chamber 2, interfering with other communications, and having an adverse effect on the human body.

In addition, the high frequency output transmitted through the lead wire 6 is transmitted to the detection unit 5.
The value is considerably larger than the signal of the temperature sensing element provided in the temperature sensing element, and in some cases, the value may become larger than the signal of the temperature sensing element. Therefore, not only is it impossible to accurately detect the temperature of the heated object 4, but also There was also a risk that the control circuit would malfunction due to the influence of the high frequency output.

The high-frequency heating device of the present invention is configured such that the high-frequency output is oscillated intermittently by the motor 10 and the output changeover switch 9 provided to perform intermittent operation. Since this is an effective method for eliminating uneven heating of the heated object 4, the temperature of the heated object 5 can be detected at the minimum necessary level compared to the conventional case where measurements are taken at multiple locations on the heated object 5. The advantage is that it only needs to be placed in one place, or in extreme cases, in one place.

Furthermore, when the output selector switch 9 is open, a small amount of current is supplied to the high voltage transformer 12 through the impedance 11, and this current prevents a rush current when the output selector switch 9 is turned on. It is possible.

Furthermore, although the value of the impedance 11 has been appropriately selected, in some cases a minute high frequency output may oscillate. Since there is almost no influence, the above-mentioned drawbacks hardly occur.

When the output selector switch 9 is closed and high frequency output is generated, the selector switch 8 is connected to the contact 8b, and when the high frequency output is off, the selector switch 8 is connected to the contact 8b. 8a to perform temperature sensing operation.

This time relationship is shown in FIG.

In FIG. 2, a is a graph showing the time of high frequency output oscillation,
b indicates that the temperature detection operation is performed when the high frequency output is not oscillating.

In addition, Figure 3 shows another method of supplying high-frequency output, and shows a method in which the supply time of intermittent high-frequency output is relatively long at first, and then gradually shortened, as shown in C. .

This method shortens the overall heating time, and at the same time gradually increases the number of high-frequency output interruptions as time passes, which is effective in eliminating uneven heating.At the same time, as shown in d, the number of temperature detections or Since the time is increased, more accurate measurements can be made.

Moreover, the operation of the changeover switch 8 and the output changeover switch 9 may be performed by the motor 10, or may be performed using other electronic circuits.

When the changeover switch 8 is connected to the contact point 8a, a signal from the detection section 5 equipped with a temperature sensing element is transmitted through the lead wire 6, enters an amplifier circuit, etc., and is converted into an appropriate form.

On the other hand, the heating method of the heated object 4 differs depending on its type, such as fat, carbohydrate, protein, etc.
Since the heating temperature varies depending on the food to be cooked, the cook indicates a heating temperature that takes these into consideration.

This is set at the set value shown in FIG. 1, and when the temperature of the heated object 4 reaches this set value, the control circuit is activated, the control relay 13 is activated, and the high frequency output is stopped.

In this embodiment, the control relay 13 is used to stop the high frequency output.
However, for example, if the gate signal of a thyristor is
It is obvious that the same effect can be obtained with other methods such as F.

Furthermore, when the high frequency output is oscillating, the changeover switch 8 is connected to the contact 8b side, and the contact 8b is connected to the heating chamber wall 1, so the output wire 6 and the shielded wire 7 are short-circuited. There is no fear that the high frequency output will leak outside the heating chamber 2.

Furthermore, in order to completely prevent leakage of high frequency output, it is preferable to provide the changeover switch 8 as close to the heating chamber wall 1 as possible.

In addition, in the embodiment of the present invention, a temperature sensing element or the like is used to detect the heating state of the object to be heated 4, but in short, any other element is sufficient as long as it can detect the heating state. It is clear that exactly the same effect can be obtained even if, for example, an element sensitive to humidity is used.

As explained above, according to the present invention, there is no need to move the sensing element, so there is no loss time required for moving the sensing element, which was required in the conventional method, and the sensing element itself does not move around the food after it comes into contact with the food. This eliminates the loss time required to reach the desired temperature, and the electrical switching means allows the heating state of food to be detected with high accuracy in an extremely short period of time and without being affected by the harmful effects of microwaves. .

Therefore, it is possible to provide an extremely superior high-frequency heating device that can detect the heating state of food with high reliability without sacrificing the most important feature of the high-frequency heating device, which is speed-of-second cooking.

Furthermore, since the measurement is performed when the high-frequency output is not oscillating, it has the great advantage of being able to accurately measure the temperature.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of a high-frequency heating device showing an embodiment of the present invention, Fig. 2 is a diagram showing the relationship between high-frequency output and temperature detection by the same device, and Fig. 3 is a diagram showing an embodiment of the same device. There is. 5...detection section, 6...take-out line, 7.
...Shield wire, 8...Selector switch,
9... Output selector switch, 13... Control relay

Claims (1)

[Scope of utility model registration request] a heating chamber that accommodates an object to be heated; a high-frequency oscillator that supplies high frequency waves into the heating chamber; a detection section disposed within the heating chamber that detects the heating state of the object to be heated; an extraction line for passing through a small hole provided in the chamber wall and leading out of the heating chamber; a shield means for protecting the detection unit and the extraction line from high frequency waves and having one end connected to the heating chamber wall; and a high frequency output. an output changeover switch for causing intermittent oscillation; and an output changeover switch connected to the take-out line and configured to detect the heating state of the heated object based on a signal from the detection section when the high-frequency output is substantially zero. A high-frequency heating device comprising: a changeover switch that opens and closes synchronously with the temperature of the object to be heated; and a control means that stops high-frequency output when the temperature of the object to be heated reaches a predetermined value.