JPS6029195B2 - High frequency heating device - Google Patents

Description

[Detailed description of the invention] The present invention relates to a high frequency heating device equipped with a temperature detection section.

Figure 1 shows the general structure of this type of high-frequency heating device.
2 is a heating chamber, 2 is an object to be cooked placed in the heating chamber, 3 is a magnetron that oscillates microwaves to heat the object to be cooked, and 4 is an iron in a closing hole 5 approximately in the center of the upper wall of the heating chamber 1. a microwave prevention ring that is inserted into the microwave and that allows the infrared rays emitted by the food to be cooked 2 to pass through but blocks the microwave; 6 is a chopper that periodically cuts off the infrared rays that have passed through the ring;
7 is a motor that periodically rotates the chopper; 8 is a concave mirror that alternately reflects and concentrates the infrared rays emitted by the food to be cooked 2 and the chopper 6 due to the above-mentioned interruptions; 9 is located approximately at the east concentration point of the concave mirror; and receives the infrared rays, thereby causing the food to be cooked 2
This is an infrared detection element of an electric current type as a temperature detection section that outputs a signal corresponding to the temperature of , and the detection element is formed of lithium tantalate (LITa03) crystal or the like. The temperature of the food to be cooked 2 is measured based on the temperature signal from the Sagiden type infrared detection element 9. In such a configuration, when the food to be cooked 2 is placed outside the measurement field of the pyroelectric infrared detecting element 9 through the microwave prevention ring 4 as shown by the two-dot chain line, the pyroelectric infrared The detection element 9 outputs a signal corresponding to the temperature at the bottom of the heating chamber 1, which hardly changes in a low temperature state.

Therefore, for example, when performing a temperature operation in which high-frequency heating is terminated when the temperature of the food to be cooked 2 reaches 80°C, the infrared detecting element 9 will not output a temperature signal of 80°C, and the high-frequency heating will continue permanently. There was a risk that the food to be cooked 2 would catch fire. Furthermore, since the above-mentioned temperature operation is performed permanently even when the food 2 is not loaded, there is a risk of dry cooking. The present invention has been made in view of new points, and one embodiment of the present invention will be described in detail below with reference to an electrical block diagram of main parts.

That is, in FIG. 2, there is an output circuit that amplifies and detects the temperature signal from the infrared detection element 9 and outputs a DC voltage corresponding to the temperature of the food to be cooked 2, and the DC voltage is If the temperature of the food to be cooked 2 is high, the value becomes large, and in the opposite case, it becomes small.

11 converts the DC voltage from the output circuit 10 into a frequency,
In a V-F converter that outputs pulses as shown in FIG. 3a according to such a frequency, the output pulse interval 1 becomes small if the DC voltage from the output circuit 10 is large (in such a case,
(the above frequency becomes large), and in the opposite case it becomes large.

Therefore, if the DC voltage input to the V-F converter 11 is large, the number of pulses output in a certain period of time will be large, and in the opposite case, the number of pulses will be small. 12 is a microprocessor formed of a semiconductor large-scale integrated circuit;
is an output terminal of the microprocessor 12 that periodically outputs a pulse with a predetermined time width t, which is much larger than the pulse output from the V-F converter 11, as shown in FIG. 3b;
13 is an AND gate that outputs the AND of the output from the output terminal and the output from the V-F converter 11.

Therefore, as shown in FIG.
The pulses arriving from 1 will be output as they are.
14 is a counter, and the contents of the counter are sent to the output terminal ○ above.
, is released by a reset pulse as shown in Figure 3 d before outputting the pulse from , and then released by a reset pulse as shown in Figure 3 d before the output state 0 is released, and then the upper The number of output pulses from the AND gate 13 operating while pulses are being output from the output terminal ○ is counted.

(RESET) is a reset output terminal of the microprocessor 12 that outputs the IJ set pulse, 1 is an input terminal that inputs the output of the counter 14 to the microprocessor 12, and 15 is an input terminal of the microprocessor 12.
A digital display unit is connected to the display output terminal (DIS) of the device, and the display unit operates to display the temperature of the food to be cooked 2 based on the count of the counter 14 according to the temperature of the food to be cooked 2. The operation period is 1' when the pulses at the output terminals ○ and 1 are stopped, which comes immediately after the count by the counter 14.

02 is the output terminal of the microprocessor 2 which generates a single pulse as shown in FIG. A gate unit that opens the gate only when a single pulse arrives; 18 is a storage unit that stores the contents of the counter 14 at the time when the gate unit opens the gate; 03
is the microprocessor 12 which generates a single pulse as shown in FIG.
The output terminal 19 is a D/A converter, and the output terminal 03 is a D/A converter.
The gate is opened only during the arrival of a single pulse from the output circuit 10 to input the contents of the storage section 18, which is a digital signal, and operates to convert the digital signal into an analog signal corresponding to the signal from the output circuit 10.

Reference numerals 20 and 21 refer to gate portions that open the gates only during the arrival of a single pulse from the output terminal 03, similar to the D/A converter 19, and 22 refers to the D/A converter that is input when the gate portions 20 and 21 are opened. The comparator compares the analog signal of the output circuit 19 with the output signal of the output circuit 10, and outputs a predetermined signal if the difference between the two signals is smaller than a predetermined value.

23 is a key input section installed on the front panel (not shown) of the main body of the high-frequency heating device, and the key input section includes a START key for starting temperature operation, a STOP key for stopping temperature operation, and numeric keys from 0 to 9. Equipped with:

24 is a power supply circuit that supplies power to the magnetron 3; 12
converts the predetermined signal from the comparator 22 into the MA. An input terminal for inputting to the T microprocessor 12, the microprocessor 12 to which the signal from the key input section 23 is inputted.
The input terminal 04 transmits a control signal for stopping the oscillation of the magnetron 3 in the microprocessor 12 to the power supply circuit 24 by the predetermined signal to the input terminal 12.
This is an output terminal of the microprocessor 12 that outputs to the microprocessor 12.

The output terminal 04 is connected to the magnetron 3 by the microprocessor 12 by operating the key input unit 23.
A control signal for oscillating or stopping oscillation is also output to the power supply circuit 24. In the above configuration, when performing a temperature operation in which the high frequency heating is to be terminated when the temperature of the food to be cooked 2 reaches 8,000, for example, the key input section 23 is operated to operate the "Okamon".

If so, it's a microphone. The o processor 12 controls the power supply circuit 24 to start oscillation of the magnetron 3. The counter 14 is then reset by a signal from the reset output terminal (RESET). After that, the first pulse 16 from the output terminal 0 is input to the AND gate 13, so during that time the infrared detection element 9, the output circuit 10, the V-F converter 11
The number of pulses corresponding to the temperature of the food to be cooked 2 is counted by the counter 14 via the AND gate 13 as described above. Then, when the output of the first pulse 16 is completed from the output terminal ○, the microprocessor 2 inputs and processes the count contents of the counter 14, and displays the temperature of the food 2 immediately after the temperature operation starts on the display section 15. At the same time, a single pulse is immediately output from the output terminal 02. Therefore, since the gate section 17 opens the gate, the count contents of the counter 14 are stored in the storage section 18. This means that the content corresponding to the temperature of the food to be cooked 2 immediately after the start of the temperature operation has been stored. After that, reset output terminal (RESET) and output terminal 0. Since the pulses described above are output periodically and alternately, the temperature of the food to be cooked 2 is sequentially displayed on the display section 15 during the temperature operation.
will be displayed. However, since the output terminal 02 does not generate any pulse other than the single pulse mentioned above to open the gate of the gate section 17, the above-mentioned contents are held in the storage section 18. After that, a certain period of time T (
For example, after one minute has elapsed, a single pulse is output from the output terminal 03, so the D/A converter 19 opens the gate only during the arrival of the single pulse and outputs the contents of the storage unit 18 as a digital signal. The signal of the circuit 10 is converted into an analog signal corresponding to the signal of the circuit 10. At the same time, the gate sections 20 and 21 also open their gates only when a single pulse arrives from the output terminal 03. Therefore, the analog signal (
That is, the temperature signal of the infrared detection element 9 immediately after the start of temperature operation) is the output signal of the output circuit 10 at such time (
That is, since the temperature signal is input to the comparator 22 together with the temperature signal of the infrared detection element 9 (at the time when one minute has elapsed from the start of temperature operation), the comparator 22 compares both input signals. Then, assuming that the food to be cooked 2 is placed at the position indicated by the solid line shown in FIG. The difference (
Incidentally, the difference between the two signals in such a case corresponds to a considerable temperature difference in the food to be cooked 2 that occurs within one minute immediately after the start of the temperature operation.

) becomes larger than the above-described predetermined value, and the comparator 22 does not output the predetermined signal. That is, the self-comparator 22 detects the food to be cooked 2 when one minute has elapsed from the start of the temperature operation.
The microprocessor 2 recognizes that the temperature is normally placed in the heating chamber 1, and therefore the temperature operation is continued normally thereafter by the microprocessor 2. In other words, the temperature of the food to be cooked 2 is 80
The microprocessor 12 sequentially displays the temperature on the display unit 15 until the temperature reaches 80℃.
Then, the microprocessor 1 detects this information and controls the power supply circuit 24 to stop the oscillation of the magnetron 3. Therefore, the above-mentioned temperature operation ends. However, if the food to be cooked 2 is placed at the position indicated by the two-dot chain line in FIG. The difference in temperature corresponds to a slight temperature difference at the bottom of the heating chamber 1 that occurs during one minute from the start of temperature operation.) is smaller than the above-mentioned predetermined value,
Comparator 22 will output a predetermined signal. That is, the comparator 22 identifies that the food to be cooked 2 is not placed in the normal position in the heating chamber 1 one minute after the start of the temperature operation. Therefore, the above predetermined signal is input to input terminal 1.
2, the microprocessor 12 controls the power supply circuit 24 to stop the oscillation of the magnetron 3. Thereafter, the temperature operation described above will not be executed unless the food to be cooked 2 is laid out again at the position indicated by the solid line shown in FIG. 1 and the 4 OSTART key is operated again.

Also, in the case of dry cooking, the oscillation of the magnetron 3 is similarly stopped. Incidentally, if the STOP key of the key input unit 23 is operated, the temperature operation is stopped regardless of the output signal of the comparator 22.

In the embodiments of the present invention, the high-frequency heating device is provided with only the function of temperature control, but it may also be provided with other cooking modes such as timer control.

Furthermore, in the embodiment of the present invention, the comparison operation in the comparator 22 was performed only when 1 minute had passed after the start of temperature operation, but after 2 minutes,
It may be performed sequentially such as 3 minutes, . . . when the elapsed time has elapsed.

Further, in the embodiment of the present invention, the temperature detection section is the pyroelectric infrared detection element 9, but it may be a temperature probe with a built-in thermistor. Even in this case, in the state where the temperature probe is not inserted into the food to be cooked 2 (corresponding to the state where the food to be cooked 2 mentioned above is placed outside the measurement field of the element 9), or in the state of dry cooking, the above-mentioned condition is applied. Similarly, the oscillation of the magnetron 3 is stopped. Further, the present invention includes any high frequency heating device within the scope of the present invention.

As detailed above, according to the high-frequency heating apparatus of the present invention, even though the food to be cooked is placed inside the heating chamber, the temperature detection section cannot detect the temperature of the food to be cooked and temperature operation cannot be performed. Even if the food to be cooked is not placed in the heating chamber, such a condition can be detected very easily and the oscillation of the magnetron can be stopped, so that the food to be cooked will ignite as described above. It is extremely safe because there is no problem and the empty cooking condition does not continue.

Furthermore, according to the present invention, there are also the following effects. In other words, even if the temperature of the food to be cooked is detected by the temperature detector, if the amount of food to be cooked is extremely large and it is heated at low output, the temperature of the food to be cooked is hardly expected to rise and the temperature operation is stopped. Sometimes, the set temperature is not reached, effectively resulting in a malfunction, and high-frequency heating is performed for an abnormally long period of time, but such heating is stopped immediately because there is no temperature rise, thereby preventing the above-mentioned malfunction.

[Brief explanation of the drawing]

Figure 1 is a schematic cross-sectional view of a typical high-frequency heating device;
The figure is an electrical block diagram of the main parts of the high-frequency heating device according to the embodiment of the present invention, and FIG. 3 is an output waveform diagram of the main parts in FIG. 2. 9...Atsuden type infrared detection element (temperature detection section), 18
...Storage unit, 22...Comparator. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1 In a high-frequency heating device equipped with a temperature detection section, the temperature at the start of high-frequency heating is detected, and the temperature after a certain period of time has passed from the start of heating, and if the difference between the two detected temperatures is less than a predetermined value, the high-frequency A high-frequency heating device characterized by stopping heating midway.