JP2003115374A - High frequency heating equipment and magnetron drive controlling method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide high frequency heating equipment, which suppresses change of the heating energy, which is impressed to foods, by suppressing generating time of the unstable initial moding as much as possible. SOLUTION: It has a filament power supply 9, which drives a magnetron 1, a positive electrode power supply 13, a filament current detection means 16, a positive electrode power supply control means 18, and the control equipment 4 that controls these. Since the oscillation control of the magnetron is carried out only when the filament has been heated enough by conducting electricity of the positive electrode 13 by the positive electrode power supply control means 18, after the filament current has become in a stable state by the signal, which has been detected by the filament current detection means 16, the initial moding generating time can be suppressed sharply.

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 device that heats food by high-frequency heating energy generated while controlling a power supply device for driving a magnetron.

[0002]

2. Description of the Related Art Conventionally, as a high-frequency heating apparatus of this kind represented by a microwave oven for business use used in a fast food shop or the like, for example, one described in JP-A-5-29075 is known. there were. FIG. 6 shows the conventional high-frequency heating device described in the above publication.

In FIG. 6, 1 is a magnetron, 2 is a driving power source for driving the magnetron, 3 is a current transformer, 4 is a control device, 5 is an operating device, and 6 is a display device. When the operating device 5 is operated in this configuration and the power is turned on, a signal is sent to the control device 4, the control device 4 is activated, and the filament of the magnetron 1 is heated.
Generates microwaves. Then, the control device 4 reads the initial moding time of the magnetron 1 until the current value at which the magnetron 1 stably oscillates is reached. The standard initial moding time for each food and the current value are set in advance, and if the set current value is reached in a time shorter than the standard initial moding time, it is determined that the magnetron 1 is operating normally. Then, the display section 6 displays “heating”, “blue lamp lighting”, etc. to continue the heating, while the current value is reached for a time longer than the reference initial moding time, the magnetron is turned on. 1 is judged to be the end of life, and the display device 6 displays "failure", "red lamp lighting", etc.,
The heating is stopped and the exchange of the magnetron 2 is promoted.

[0004]

However, in the above-mentioned conventional structure, it is possible to prevent the heating of food by the magnetron whose output is reduced due to moding, but it is gradually changed. It is impossible to prevent the decrease of the irradiation time of the real high frequency energy due to the shortening of the stable oscillation time of the magnetron due to the generation time of the magnetron initial moding. It is necessary to make the value as close as possible to the value, which is uneconomical because the frequency of magnetron replacement is high, and malfunction due to changes in the surrounding environment, that is, the time at which initial moding occurs due to differences in voltage and frequency of repeated use. However, there is a problem in that In particular, in this type of high-frequency heating device, it is required to shorten the heating time of food, and for example, the heating time is often set to 10 seconds or less. Generally, the initial moding occurrence time of a magnetron is a normal magnetron, but depending on the situation,
Moreover, as the number of times of use increases, it takes several seconds. in this case,
Depending on the setting of the heating time, the actual irradiation time of high-frequency energy may range from several% to 50% or more of the set heating time, and the heating energy of food is halved compared to immediately after replacing the magnetron, and it is extremely unheated. The problem of becoming a state is becoming apparent.

The present invention is to solve the above-mentioned conventional problems. From the viewpoint that the initial moding generation until the magnetron reaches stable oscillation depends on the change in the electron emission capability from the filament. It is an object of the present invention to provide a high-frequency heating device that can heat foods with a sufficient electron emission and bring them to an appropriate finishing temperature.

[0006]

In order to solve the above-mentioned problems, the filament is heated before the anode power source of the magnetron starts to be energized, and the oscillation of the magnetron is started after the electron emission from the filament is stabilized. It was done like this.

As a result, the initial moding occurrence time can be shortened as much as possible, and the proportion of the preset heating operation time can be reduced, and the change in heating energy applied to the food can be greatly reduced.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 is for driving a filament power supply for heating a filament of a magnetron which generates high-frequency energy, a filament current detecting means for detecting a current flowing through the filament, and an anode drive. By providing such an anode power source and an anode power source control means for controlling the anode power source of the magnetron according to the output of the filament current detection means, the anode voltage can be applied after the current flowing through the filament is stabilized in a steady state. Therefore, it is possible to eliminate the unstable initial modding occurrence time which varies variously depending on the situation, and to prevent the heating energy applied to the food due to the initial moding occurrence from changing in any state.

The invention as defined in claim 2 is particularly characterized by claim 1.
Anode power supply control means for controlling the anode power supply of the magnetron of the high-frequency heating apparatus described in 1, the output value of the filament current detection means, and detects both of the change in the output value, a configuration for controlling the anode power supply control means of the magnetron. By doing so, it becomes possible to clearly determine that the filament current has stabilized to a steady value, and prevent malfunctions due to deviations in the filament current absolute value due to changes in external conditions such as changes in voltage and heating frequency. You can

According to a third aspect of the present invention, there is provided a filament power source for heating a filament of a magnetron which generates high frequency energy, a filament current detecting means for detecting a current flowing through the filament, and an anode power source for driving an anode. An arrangement for providing an anode power source control means for controlling the anode power source of the magnetron according to the output of the filament current detection means, a filament power source control means, and a means for storing the history of energization, and controlling the filament power source according to the stored history By including, by controlling the current flowing against the change in the steady current of the filament due to voltage change or change over time, by stabilizing this, the initial moding occurrence time is suppressed as much as possible, and at the same time,
By changing the filament resistance due to the deterioration of the magnetron itself, changing the filament surface that inhibits electron emission, and eliminating the gas generated in the tube, the initial moding occurrence time of the magnetron is made constant over a long period of time. It is possible to prevent the change in heating energy applied to food from being affected.

According to a fourth aspect of the present invention, a filament power source for heating a filament of a magnetron for generating high frequency energy is provided with a filament current detecting means for detecting a current flowing through the filament and an output of the filament current detecting means. According to the control of the anode power supply of the magnetron according to the anode power supply control means, the anode voltage can be applied after the current flowing through the filament is stabilized to a steady state, and the unstable initial state varies variously depending on the situation. It is possible to eliminate the moding generation time and to prevent the heating energy applied to the food from changing due to the initial moding generation in any state.

According to a fifth aspect of the present invention, the anode power source control means for controlling the anode power source detects both the output value of the filament current detecting means and the change in the output value to control the anode power source of the magnetron. This makes it possible to clearly determine that the filament current has stabilized to a steady value, and to prevent malfunctions due to deviations in the filament current absolute value due to changes in external conditions such as changes in voltage and heating frequency. it can.

According to a sixth aspect of the present invention, a filament power source for heating a filament of a magnetron for generating high frequency energy has a filament current detecting means for detecting a current flowing through the filament and an output of the filament current detecting means. A filament power supply control means for controlling the anode power supply of the magnetron, a filament power supply control means, and a means for storing the history of energization are provided, and the filament power supply is controlled according to the stored history, so that the filament due to voltage change or aging change By controlling the flowing current against the change in the steady current of and stabilizing it,
By suppressing the initial moding generation time as much as possible and making it constant, at the same time, by changing the filament resistance due to the deterioration of the magnetron itself, changing the filament surface that inhibits electron emission and eliminating the gas generated in the tube, It is possible to make the initial moding occurrence time of (1) constant over a long period of time so as not to affect the change of heating energy applied to the food.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. It should be noted that the same numbers are given to the configurations having the same functions as those of the conventional example, and the description thereof will be omitted.

(Embodiment 1) FIG. 1 shows a circuit of a high-frequency heating apparatus according to Embodiment 1 of the present invention.

In FIG. 1, the magnetron 1 comprises a filament power source 9 mainly composed of a filament transformer 8 for converting a power source voltage into a voltage and a current required for heating the filament 7, and a high DC voltage required for driving an anode. Ferro-resonant transformer 10 to convert to, rectifier 11, condenser 1
The anode power source 13 composed of two components constitutes a circuit configuration that is independently driven. The anode power supply 13 may be a so-called inverter power supply that drives and disconnects the primary circuit at a cycle of several tens of kHz in addition to the embodiment. Filament 7 and filament transformer 8 of this magnetron 1
Current detecting means 16 configured such that a part of the wiring connecting to the secondary winding 14 of the current transformer 15 penetrates the detection coil of the current transformer 15.
Is provided to detect the current flowing through the filament 7. A control relay 17 is provided in the primary circuit of the anode power source 13.
Anode power supply control means 18 composed of a circuit having a core is connected in series, and the contact 19 of the control relay 17 is opened and closed to enable intermittent control of the input to the anode power supply 8. The control relay 17 has a mechanical contact, but as another embodiment, a bidirectional switching element such as a triac or a semiconductor for switching the above-mentioned inverter power supply may be used. in this case,
The life as a contact can be almost ignored, and more advanced control becomes possible. In addition, a power switch 20 for turning on the power of the apparatus and an operation relay 21 for starting an operation are connected to the power source.

These devices are based on the program stored in the memory circuit of the microcomputer 22 arranged in the control device 4 and the signal current detected by the filament current detection means 16, and the operation relay 21 and the anode power supply control means. 18 is controlled. Further, as in the conventional example, an operating device 5 including a switch group for operating the device and a display device 6 for displaying the operating state of the control device 4 are provided.

The operation and action of the high-frequency heating device configured as described above will be described below. FIG. 2 is a flowchart showing the operation of the microcomputer 22 in the first embodiment.

When the start switch of the operating device 5 is operated, the operation switch 21 is turned on (step S1) and at the same time the timer 1 starts operating. The filament transformer is energized and the filament 7 connected to the secondary winding 14 is energized. Timer 1 operates (step S1-2)
Then, in the embodiment, it is determined whether 0.2 seconds has elapsed.
(Step S1-3) No control is performed during this period. In order for the filament 7 of the magnetron to properly emit electrons, a temperature of about 1700K is usually required. Therefore, materials such as trume tungsten that are unlikely to melt or deteriorate even at extremely high temperatures are used. Indicates that the resistance value at room temperature is extremely lower than the resistance value at the operating temperature.

Therefore, immediately after the start of energization, the magnetron 1
Regardless of the state of the filament 7, the current that is close to a short circuit flows through the secondary winding of the filament transformer 8.
In the present embodiment, the filament 7 of the magnetron 1
In order to accurately detect the state of, the state is not detected immediately after energization. 0.2 seconds after the filament 7 is gradually heated and its current begins to decrease, the signal current detected by the current transformer 15 is detected (step S1-4).
The microcomputer 22 stores a preset reference current value and compares it with this set value (step S1-
Perform 5). The reference current value is set to a value slightly larger than the signal current in the case of the filament current flowing during the normal operation, and when it becomes less than the set value, the signal of the control relay 17 in the anode control means 18 is sent. (Step S1
-6), the contact 19 is closed and the anode power supply 13 is energized, the output voltage of the anode power supply 13 is applied between the filament 7 of the magnetron 1 and the anode, and the magnetron 1 starts oscillating.
If it is larger than the reference current value in step S1-5, it is determined that the filament 7 is in an unheated state, and the current is detected again.

According to the above construction, the magnetron 1 always acts so that the voltage is applied to the anode only when the filament 7 is sufficiently heated and the electron emission is sufficient. Conversely, it means that it is possible to prevent the magnetron 1 from operating in a state where the filament 7 is unheated and the electron emission is insufficient, and the initial moding state due to the insufficient electron emission almost disappears. Like

As described above, in the present embodiment, the filament power source 9 for heating the filament 7 of the magnetron 1, the current transformer 15 for detecting the current flowing through the filament 7, and the anode power source 13 for driving the anode.
And a control relay 17 for controlling the anode power source 13 of the magnetron 1 according to the output of the current transformer 15, and the anode voltage after the current flowing through the filament 7 is stabilized to a steady state. Is applied, it is possible to prevent the change in heating energy applied to food by suppressing the unstable initial moding occurrence time which varies variously depending on the situation. Further, by providing a structure for starting the high-frequency heating operation, that is, the high-frequency oscillating time from the time when the anode power supply 13 starts to be energized, the electron emission from the filament 7 is not always sufficient. It is possible to measure only the energization time of the anode power source of the, and the magnetron seems to oscillate stably within the set heating time, and the heating energy applied to the food is not affected by the initial moding time. It becomes constant and the finishing temperature can be made constant. In particular, when this type of high-frequency heating device is repeatedly used, the temperature of the magnetron 1 constantly fluctuates due to the history of previous use. In the conventional case, this temperature change affects the heating state of the filament 7, and each time the temperature changes. Although the initial moding time changed and the final temperature fluctuated, the magnetron 1 oscillated after the filament current fell below a certain value. Can be greatly reduced, and an effect can be obtained for stabilizing the finish temperature.

In this embodiment, the filament 7
When the current flowing to the reference current value reaches the reference current value, the anode power supply 13 is immediately energized to bring the magnetron 1 into the oscillating state. However, in another embodiment, step S1-
There may be a case where a timer is provided between step 5 and step S1-6 and the process moves to step S1-6 after a certain time has elapsed. In this case, by appropriately setting the time of the timer, the magnetron enters an oscillating state with more stable electron emission from the filament 7, so that the initial moding state can be completely eliminated.

Further, in the present embodiment, an example in which one magnetron 1 is arranged in the apparatus is shown, but a plurality of similar configurations are provided and the anode power source 13 is provided in a state where the filament current of the last magnetron is stable. By controlling so that it is energized, it becomes possible to supply more stable heating energy to a device having a higher output, which is greatly affected by the initial moding occurrence time.

(Embodiment 2) FIG. 3 is a flow chart showing the operation of the microcomputer 22 of the high frequency heating apparatus according to Embodiment 2 of the present invention. The same reference numerals as those in the first embodiment have the same structure, and the description thereof will be omitted.

The difference from the configuration of the first embodiment is that the counter 1 is provided after step 1-5 and counting is performed by the counter. When it is determined in step S1-5 that the current is smaller than the reference current, the counter 1 is counted as once (step S2-6). When the count value of the counter 1 counts 10 times, it is determined that the filament current is stable and smaller than the set value (step S2-7), and the signal of the control relay 17 in the anode control means 18 is sent. Then, the contact 19 is closed to energize the anode power source 13, the output voltage of the anode power source 13 is applied between the filament 7 of the magnetron 1 and the anode, and the magnetron 1 starts oscillating. If it is larger than the reference current value in step S1-5, it is determined that the filament 7 is in an unheated state, and the counter 1 is reset to 0 (step S2-9).
Then, the current is detected again. Also, until the counter 1 counts 10 in step S2-7, step S1-
Returning to 4, the current is detected. In addition, in the present embodiment, the counting judgment of the counter 1 is set to 10 in step 2-7, but in other embodiments, an optimum value is appropriately set depending on the type of the magnetron 1 and the current detection period.
It may have different values.

According to the above structure, the magnetron 1 always operates so that the filament 7 is sufficiently heated and the voltage is applied to the anode after the electron emission is sufficiently maintained for a certain period of time. In this case, the anode power source is not energized until the filament current becomes stable even if the absolute value of the filament current changes due to the external environment, for example, changes in the voltage of the power source or variations in individual components.

As described above, the filament current is detected, both the output value of the current transformer 15 and the change in the output value are detected, and the anode power source 13 of the magnetron 1 is controlled. It is determined that the filament 7 is not sufficiently heated even if the voltage drops and the filament current is below the set current before it is sufficiently heated, and the filament 7 is not heated and the emission of electrons is insufficient. It becomes possible to more accurately prevent the magnetron 1 from operating in such a state, and it becomes possible to eliminate the initial moding state caused by the lack of electron emission.

(Embodiment 3) FIG. 4 shows a circuit of a high-frequency heating apparatus according to Embodiment 3 of the present invention. The difference from the first embodiment is that the filament power supply control means and the means for storing the history of energization are provided, and the filament power supply during magnetron oscillation is controlled based on the stored contents of the energization history. The same reference numerals as those in the first embodiment have the same structure, and the description thereof will be omitted.

In FIG. 4, reference numeral 23 is a filament power supply control means, which is composed of a switching element 24 such as a triac and its control circuit. The energization phase angle is changed by a signal from the control device 4 to control the input of the filament power supply 9. Make a configuration. Further, the microcomputer 22 includes a counter function for counting the number of operations inside, and a storage device 25 for storing the contents of the counter outside.
Is provided.

The operation and action of the high-frequency heating device configured as described above will be described below. FIG. 5 shows a flowchart of the microcomputer 22 in the third embodiment.

When the start switch of the operating device 5 is operated and the operation switch 21 is turned on, the filament transformer 8 is energized and the filament 7 connected to the secondary winding 14 is energized. 18
The steps until the control relay 17 closes the contact 19 and starts high frequency heating are the same as those in the second embodiment. In this embodiment, thereafter, control is performed according to the following program.

First, the control relay 17 is turned on and the contact 19
After closing the
The filament current is detected again (step 3-1).
The microcomputer 22 stores a preset reference current range during high frequency oscillation and compares it with this set range (step S3-2). The reference current range is set centering on the optimum value of the filament current flowing during normal operation, and if it is within the set range, the counter 2 is counted as once, and (step S3-3) a part of the storage device 25. One count is stored in (step S3-4). Counter 2
Is counted as a normal use state until it counts 10,000 times (step S3-5) (step S3-6), and the heating operation is terminated when the remaining time becomes 0 ( Step S3-7).

If the filament current is out of the reference current range in step S3-2, it is determined whether the filament current is larger or smaller than the current range (step S3-8).
If it is less than the set value, the microcomputer 22 sends a signal to increase the energization phase angle of the triac 24 in the filament control means 23 (step S3-).
9). On the other hand, if it is larger than the set value, the microcomputer 22 sends a signal to decrease the energization phase angle of the triac 24 in the filament control means 23 (step S3-10), returns to step S3-2, and detects the current again. I do.

In step S3-5, the counter 2 becomes 100.
When counting 00, the counter-3 is counted as once (step S3-11). It is judged whether or not the counter 3 is within 100 times (step S3-12), 10
If it is within 0 times, the conduction phase angle of the switching element is increased (step S3-13), and the filament current is increased to 20%.
increase. The set value of the reference current referred to at the time of judgment in step 1-5 is also set to be 20% larger than the initial set value (step S3-14), and the set high-frequency heating time is measured. Returning to (step S3-5), the heating operation ends when the remaining time becomes 0 (step S3-6). When the counter 3 exceeds 100 times, the energization phase angle of the switching element 24 is returned to the initial value (step S3-15), and the set value of the reference current referred to at the time of the determination in step 1-5 is also the initial value. Return to the set value (step S3-14), reset the counters 2 and 3 to 0 (step S3-16), and measure the set high-frequency heating time (step S3-5).
Return to. With the above-described configuration, the following effects occur in the operation of the magnetron 1.

That is, first, the temperature of the filament 7 that changes variously, that is, the temperature of the filament 7, which changes due to the cathode reverse heating phenomenon caused by the increase and decrease of the reflected wave due to the change of the power supply voltage during high frequency oscillation and the difference of the heated object such as food to be heated, By controlling the conduction phase angle of the current, the current is kept constant, the occurrence of moding due to the decrease of the electron emission capability due to the insufficient current is suppressed, and the change over time of the magnetron is reduced.

Further, inside the magnetron 1, there is generally a getter for inhibiting the operation of the electrons generated by the filament 7 in the action space, adsorbing the gas that causes the moding, and performing the operation efficiently. Although it is provided near the filament, this getter is, for example, as in this embodiment,
By raising the filament 7 to a temperature higher than the normal state 100 times per 10,000 times, the adsorption capacity can be further increased and the gas in the tube can be removed during that time.

Further, in the present embodiment, in the case of repeating the heating for a short time, considering that the number of times of energization has a greater effect on the life than the total of the heating times, the counter 2 is used for storing the energization history of the device. However, depending on the operation pattern of the high frequency heating device, the filament current may be increased at regular intervals depending on the energization time.

Further, even if the current is properly controlled, the resistance of the magnetron filament may gradually increase due to surface roughness or the like, and the electron emission capability may decrease, depending on the conditions of use. . In view of this case, as another embodiment, the filament current is increased by the energization phase angle of the filament power supply control unit 23 at a fixed time, every number of times, or gradually over the set life number and time from the initial stage, and from the initial stage, The emission of electrons from the filament 7 may be kept constant until the set life time is reached.

As described above, according to the output of the filament power source 9 for heating the filament 7, the current transformer 15 for detecting the current flowing through the filament, the anode power source 13 for driving the anode, and the output of the current transformer 15.
Control relay 17 for controlling the anode power supply of magnetron 1
And a switching element 2 for controlling the filament power supply
4 and a storage device 25 that stores a history of energization, and a configuration that controls the filament power supply 9 in accordance with the history such as the number of times of storage, thereby changing the steady-state current of the filament 7 due to a voltage change or a change over time. By controlling the current and stabilizing it, the initial moding generation time is minimized and stabilized, and at the same time, the filament resistance changes due to the deterioration of the magnetron 1 itself and the surface of the filament 7 that inhibits electron emission. Of the magnetron 1 can be kept constant for a long period of time by eliminating the change in temperature and the gas generated in the tube so as not to affect the change in heating energy applied to the food. I can.

[0041]

As described above, according to the first to sixth aspects of the present invention, the anode voltage is applied after the current flowing through the filament of the magnetron is stabilized to a steady state, and it varies depending on the situation. By suppressing the stable initial moding occurrence time as much as possible, it is possible to significantly suppress the change in heating energy applied to food.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a high-frequency heating device according to a first embodiment of the present invention.

FIG. 2 is a flowchart showing the operation of the microcomputer of the high frequency heating apparatus according to the first embodiment of the present invention.

FIG. 3 is a flowchart showing the operation of the microcomputer of the high frequency heating apparatus according to the second embodiment of the present invention.

FIG. 4 is a circuit diagram of a high frequency heating device according to a third embodiment of the present invention.

FIG. 5 is a flowchart showing the operation of the microcomputer of the high-frequency heating device according to the third embodiment of the present invention.

FIG. 6 is a circuit diagram of a conventional high frequency heating device.

[Explanation of symbols]

1 magnetron 4 control device 9 filament power supply 13 Anode power supply 16 Filament current detection means 18 Anode power supply control means 23 Filament power control means 25 storage

Claims (6)

[Claims] 1. A filament power supply for heating a filament of a magnetron for generating high-frequency energy, a filament current detection means for detecting a current flowing through the filament, an anode power supply for driving an anode, and the filament current detection means. A high frequency heating device comprising: an anode power source control means for controlling the anode power source of the magnetron according to the output. 2. The anode power supply control means for controlling the anode power supply is configured to detect both the output value of the filament current detection means and a change in the output value to control the anode power supply of the magnetron. The high-frequency heating device described. 3. A filament power supply for heating a filament of a magnetron for generating high-frequency energy, a filament current detection means for detecting a current flowing through the filament, an anode power supply for driving an anode, and the filament current detection means. A high-frequency heating apparatus comprising an anode power source control means for controlling the anode power source of the magnetron according to the output, a filament power source control means, and a means for storing a history of energization, and a configuration for controlling the filament power source according to the stored history. . 4. A filament power supply for heating a filament of a magnetron for generating high frequency energy, a filament current detection means for detecting a current flowing through the filament, and an anode power supply of the magnetron controlled according to an output of the filament current detection means. And an anode power source control means for controlling the magnetron drive control method. 5. The anode power supply control means for controlling the anode power supply controls both the output value of the filament current detection means and the change in the output value to control the anode power supply of the magnetron. 4. The magnetron drive control method according to item 4. 6. A filament power supply for heating a filament of a magnetron for generating high frequency energy, a filament current detection means for detecting a current flowing through the filament, and an anode power supply of the magnetron controlled according to an output of the filament current detection means. A magnetron drive control method comprising: providing an anode power supply control means, a filament power supply control means, and means for storing a history of energization, and controlling the filament power supply according to the stored history.