JP3446554B2 - High frequency heating equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply for driving a magnetron of a high frequency heating apparatus using a magnetron and a control method thereof.

[0002]

2. Description of the Related Art A conventional high-frequency heating device will be described with reference to the drawings.

As shown in FIG. 20, the conventional high-frequency heating apparatus uses a circuit configuration called a single-stone voltage resonance type circuit for a high voltage power supply circuit. 2 is 60Hz or 50H
z is a commercial power source, and 58 is a rectifier for full-wave rectifying the commercial power source to rectify the commercial power source to form a DC power source. Reference numeral 4 is a leakage type transformer, 6 is a semiconductor switching element, 7 is a drive circuit for outputting a pulse signal for driving the semiconductor switching element 6, 59 is a rectifier circuit connected to the secondary side of the leakage transformer 4, and 11 is a magnetron. . The leakage type transformer 4 and the capacitor 5 constitute a resonance circuit,
By this action, the voltage waveform of the semiconductor switching element 6 becomes sinusoidal. The collector voltage and current waveforms of the semiconductor switching element 6 are as shown in FIG.

With this resonance circuit, the semiconductor switching element 6 can be turned on after the voltage becomes zero,
Almost no switching loss (portion where voltage and current overlap) when turned on occurs. When turned off, the current sharply cuts off, but since the voltage rises in a sine wave shape, the slope becomes gentle and the switching loss at the time of off is reduced.
In this way, the resonant circuit has the effect of reducing the switching loss of the semiconductor switching element.

However, in the high-frequency heating apparatus having such a structure, as shown in FIG. 21, there is a problem that the maximum value of the voltage applied to the semiconductor switching element 6 generates a high voltage which is four times or more the power supply voltage. is there.

In order to solve this problem, therefore, prior to the present invention, a high-voltage power supply circuit for a high-frequency heating device shown in FIG. 22 has been proposed.

In FIG. 22, 3 is a DC power source, 60 is a first capacitor, 61 is a second capacitor, and 62 is a first capacitor.
Is a semiconductor switching element, 63 is a second semiconductor switching element, 64 is a drive circuit, 4 is a leakage type transformer, 8 is a rectifier circuit, and 11 is a magnetron.

The drive circuit 64 sends a pulse signal of a predetermined frequency and duty to the first semiconductor switching element 62.
To the second semiconductor switching element 63, a pulse signal obtained by delaying the inverted signal of the second semiconductor switching element 63 by the delay circuit 65 is applied.

Regarding the operation of this circuit, FIG. 22 and FIG.
This will be described with reference to FIG. First, when the first semiconductor switching element 62 is turned on, the collector current Ic flows through the primary side of the leakage type transformer 4 (FIG. 23).
(A) State (a)}.

When the first semiconductor switch 62 is turned off,
The current flowing on the primary side of the leakage transformer 4 starts flowing toward the first capacitor 60. At this time,
The voltage of the first semiconductor switching element 62 is shown in FIG.
It becomes like (c). This voltage is the second capacitor 61
When the initial voltage of 2 is reached, the diode forming the second semiconductor switching element 63 is turned on, and the charging of the second capacitor 61 is started. Since the second capacitor 61 has a larger capacitance value than that of the first capacitor 60, the slope of the voltage of the first semiconductor switching element 62 suddenly becomes gentle and the state of FIG. (B)
Move to. If the transistor forming the second semiconductor switching element 62 is turned on at the time of this charging, the slope of the current flowing from the primary side of the leakage transformer 4 toward the second capacitor 61 becomes zero. On the contrary, the current flows from the second capacitor 61 toward the primary side of the leakage type transformer 4, as shown in FIG.
Transition to state (d). When the transistor forming the second semiconductor switching element 63 is cut off at an arbitrary time T, the state (e) in which current starts to flow from the first capacitor 60 toward the primary side of the leakage transformer 4 is entered. At this time, the slope of the voltage of the first semiconductor switching element 62 becomes steep, and decreases toward zero due to the energy of the first capacitor 60. When this voltage becomes zero, the first semiconductor switching element 6
When 2 is turned on again, the same operation is repeated from the state (a) of FIG. 23, and the switching operation for reducing the switching loss can be realized. The high-voltage power supply circuit for energizing such a magnetron controls power (output) using an electronic circuit provided in the power supply circuit. In recent years, a microcomputer etc. provided outside the high-voltage power supply circuit (hereinafter referred to as a microcomputer, etc.) Is referred to as a system control circuit), and a method of controlling from the outside has been proposed.

[0011]

However, the high-frequency heating apparatus configured so that the power control of the high-voltage power supply circuit is performed by using the system control circuit provided outside thereof has the following problems. .

That is, since the magnetron has a structure close to that of a direct heating type bipolar vacuum tube, a state in which electrons can be emitted by heating the cathode (also serving as a heater) (oscillation possible state)
It requires a startup mode that raises the cathode temperature up to. Therefore, after passing through this start-up mode, it is necessary to switch to the steady mode in which microwaves for heating foods such as food are generated, and the system control circuit requires the high-voltage power supply circuit for power (output) control. Output setting information and a control signal for switching the above two operation modes.

Further, since the time required for the magnetron to reach the oscillating state is not constant, the system control circuit must judge the timing of switching to the steady mode based on the magnetron state. It is necessary to prevent malfunctions due to noise and the like that are optimum for the output setting values.

Further, the control signal for switching the operation mode to be sent to the high-voltage power supply circuit must be in a signal form in which it can be easily identified that the start mode has been switched to the steady mode, and the power in the steady mode is output at a high frequency. It must start up smoothly to the set value.

In addition, the control signal must have a signal form that can more clearly identify that the control mode has switched from the start mode to the steady mode. Furthermore, the power in the steady mode must be smoothly transferred to the high frequency output set value.

In response to such external control from the system control circuit, the high-voltage power supply circuit must surely identify whether the operation mode information is the operating state or the stopped state.

Further, when the operation mode information is in the activated state,
It is necessary to supply electric power to the heater of the magnetron to shorten the time required for starting (starting time) and prevent application of excessive voltage to the magnetron.

Further, it is necessary to surely identify that the operation mode information is in the steady state and to control the electric power from the outside stably.

Furthermore, when the signal from the system control circuit is abnormal, the circuit must be protected.

Further, the external control signal from the system control must be quickly identified and must be constructed so as not to be affected by noise or the like.

[0021]

In order to solve the above problems, the present invention provides a system control circuit, a high voltage power supply circuit, a magnetron connected to the high voltage power supply circuit, and input current information of the high voltage power supply circuit. A current information transmission path to be sent to the system control circuit, and a control signal transmission path to send a control signal from the system control circuit to the high-voltage power supply circuit, wherein the high-voltage power supply circuit is a DC power supply obtained by rectifying a commercial power supply. A resonance circuit composed of a leakage transformer connected to the DC power supply, a capacitor connected to the first winding of the leakage transformer, and a resonance circuit connected to the first winding of the leakage transformer. A semiconductor switching element, a drive circuit for generating a pulse signal for driving the semiconductor switching element from an output set value, and the leakage transistor. Rectifier circuit of which is connected to the secondary side
And the output setting value sent to the drive circuit from the control signal
An output setting that is made up of a power supply control circuit that switches operation modes such as stop, start, and steady state of the magnetron, and the system control circuit controls the input current information to be a value commensurate with the high frequency output setting value. The power supply control circuit outputs the control signal in which information and operation mode information are multiplexed.
It was configured to send to.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION A system control circuit, a high-voltage power supply circuit, and a magnetron connected to the high-voltage power supply circuit,
The high-voltage power supply circuit includes a current information transmission path for transmitting input current information of the high-voltage power supply circuit to the system control circuit and a control signal transmission path for transmitting a control signal from the system control circuit to the high-voltage power supply circuit. A resonant circuit including a DC power source obtained by rectifying a power source, a leakage type transformer connected to the DC power source, and a capacitor connected to a first winding of the leakage transformer, and the leakage type transformer. A semiconductor switching element connected to the first winding, a drive circuit for generating a pulse signal for driving the semiconductor switching element from an output setting value, and a rectification circuit connected to the secondary side of the leakage transformer , The output set value sent to the drive circuit is the control signal.
And a power supply control circuit that switches operation modes such as stop, start, and steady state of the magnetron, and the system control circuit ensures that the input current information has a value commensurate with the high frequency output set value. Power supply control of the control signal that multiplexes the output setting information and the operation mode information
The control signal path is simplified by the configuration that is sent to the circuit .

Further, the system control circuit is used for the magnetron whose time required to reach the oscillation state is not fixed.
Since the input current information and the determination level are compared to detect that the magnetron has switched to the oscillating state, it is possible to switch between the starting mode and the steady mode in accordance with the state of the magnetron.

[0024] in and constitute a judgment level as you switch according to the high-frequency output setting value, and further, configured to predetermined time masking the detection from the beginning of the active state, the noise current information signal This prevents erroneous detection immediately after the start of operation of the high-voltage power supply circuit, which is prone to mix in.

In the operation mode information, a steady state (I) is inserted before the steady state when switching from startup to steady state,
The high voltage power supply circuit can easily identify the change.

Since the output setting information in the steady (I) period is set according to the high frequency output set value, the power applied to the magnetron can be smoothly raised to the high frequency output set value.

Further, the stationary (I) period is divided into at least stationary (I-1) and stationary (I-2), and the stationary I
-2 is different from the stationary I-1 in the discrimination level and
Insert after steady I-1 and switch from startup to steady
Smoothing and specializing the steady state (I) to the signal setting indicating the switching to the steady state makes it possible to more clearly identify the switching from the activation of the operation mode information to the steady state.

Further, since the output setting information in the steady (I-2) period is set according to the high frequency output setting value,
The power applied to the magnetron up to the high frequency output setting value,
You can start up more smoothly.

Further, the power supply control circuit identifies the operation mode information as an operation state from the time when the control signal reaches the first level or higher until it reaches the second level which is lower than the first level. Since the high-voltage power supply circuit is configured to operate, the high-voltage power supply circuit can reliably identify whether the operation mode information sent from the system control circuit is the operating state or the stopped state.

Further, the power supply control circuit discriminates the operation mode information from the activated state from the time when the control signal reaches the first level or higher to the third level or higher, and sets the control signal to the activated setting. Since the output set value added with the value is configured to be sent to the drive circuit, it is possible to secure the electric power applied to the heater of the magnetron even if the control signal has a small value equal to or lower than the third level.

The high-voltage power supply circuit is a semiconductor switch.
Comprising a voltage limiter circuit for limiting the voltage of the grayed element, the power supply control circuit for a period which is identified as start state attenuates the output set value by operating said voltage limiter circuit limits the voltage applied to the magnetron With this configuration, it is possible to prevent application of an excessive voltage to the magnetron.

Further, the power supply control circuit discriminates that the operation mode information is in the steady state from the time when the control signal reaches the second level or higher, which is higher than the first level, to the second level or lower. Since it is configured as described above, it is possible to reliably identify the transition from the starting state to the steady state. Further, at this time, since the control signal is configured to be sent to the drive circuit, the output setting information in the steady state is from the second level to the fourth level (described later) lower than the first level.
Can be set by using a wide range, that is, the output set value set in more detail can be sent to the drive circuit, so that power control from the outside can be stabilized.

Further, when the control signal is out of the normal setting range, that is, when it reaches the fourth level or higher, the power supply control circuit is configured to stop the operation of the high voltage power supply circuit. It is possible to prevent a circuit failure due to an abnormality.

Furthermore, since the output set value is configured to be used after being filtered by the control signal, the power of the high-voltage power supply circuit is affected by a sudden change of the control signal or noise due to the switching of the operation mode. The power supply control circuit can identify the operation mode information that is difficult to receive and is multiplexed in the control signal, and can quickly switch to the required operation mode.

[0035]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a circuit diagram of a high frequency heating apparatus according to an embodiment of the present invention.

In FIG. 1, the same reference numerals as those in the conventional example are the same components, and detailed description thereof will be omitted.

The high voltage power supply circuit 1 includes a DC power supply 3 obtained by rectifying a commercial power supply 2, a leakage type transformer 4 connected to the DC power supply, a first winding of the leakage transformer and a capacitor connected thereto. 5, a semiconductor switching element 6 connected to the first winding, a drive circuit 7 thereof, a rectifier circuit 8 connected to the secondary side of the leakage transformer, and a semiconductor switching element 6 The output voltage of the rectifier circuit 8 is applied to the magnetron 11. The voltage limiter circuit 9 operates so as to detect the voltage of 1 and to limit the value thereof, and the power supply control circuit 10 for switching the operation mode.

Further, the current detector 12 detects the current input to the high voltage power supply circuit 1 and inputs the current information 13 to the system control circuit 15 through the current information transmission path 14.

The system control circuit 15 uses the current information 1
The output setting information 17 is increased or decreased so that 3 matches the high frequency output setting value 16. Further, the control signal 19 in which the output setting information 17 and the operation mode information 18 such as stop / start / steady state are multiplexed is sent to the high voltage power supply circuit 1 through the control signal transmission path 20. As shown in FIG. 2, the control signal 19 in which these two signals are multiplexed represents the large / small of the output setting information 17 by the large / small of the control signal 19, and the operation mode information 18 by the value of the control signal 19. And switching of operating mode from one mode to another,
The control signal 19 is shown by passing a predetermined value.
As described above, since the signals on the control signal transmission path 20 are integrated into the control signal 19 in which the two signals are multiplexed, the path can be simplified.

In the present invention, the control signal 19 in which these two signals are multiplexed is explained with a DC voltage value, but the present invention is not limited to this method, and other methods such as frequency or the duty ratio of the PWM signal are used. Can also be expressed as Further, the current detector 12 is configured to detect the input current of the high voltage power supply circuit 1, but is configured to detect the current flowing through the magnetron 11, the current of the elements forming the rectifier circuit 8 or the like. Good. In addition, the configuration of the resonance circuit composed of the first winding of the leakage transformer 4 and the capacitor 5 connected thereto, the configuration of the rectification circuit 8 connected to the secondary side of the leakage transformer 4, or the semiconductor switching element 6 The configuration of the power portion of the high-voltage power supply circuit 1 such as arrangement is not limited to the configuration described in the present invention,
It can be applied to many configurations such as the method described in the conventional example.

Second Embodiment FIG. 3A is a configuration diagram of the oscillation detecting means 21 provided in the system control circuit 15, and the same components as those in FIG. 1 are designated by the same reference numerals.

As described above, since the magnetron 11 has a structure close to that of a direct-heat type bipolar vacuum tube, the cathode temperature rises to a state where electrons can be emitted (oscillation possible state) (hereinafter, this state is referred to as a starting state). , The impedance of the magnetron 11 is very high, and almost no current flows there. With respect to the magnetron 11 in which the time required to reach the oscillating state is not fixed, the oscillation detecting means 21 provided in the system control circuit 15 uses this characteristic to switch the magnetron 11 from the starting state to the oscillating state by using the current information. Since it is configured to discriminate when 13 has increased to the oscillation detection level 22, the activation 28 and the steady state 29 of the operation mode information 18 can be switched following the state of the magnetron 11. Moreover, no special signal for oscillation detection is required. This detection may be performed using software as shown in FIG. 3 (b).

(Third Embodiment) FIG. 4A shows the oscillation detection level 23 for determining the switching of the magnetron 11 from the startup state to the oscillation state according to the high frequency output set value 16. It is a block diagram of the means 24, The same code | symbol is attached | subjected to the same component as FIG.

With this configuration, when the high frequency output set value 16 is high, the oscillation detection level 23 can be set high accordingly, and the noise resistance characteristic at the time of high high frequency output which is generally used can be improved. In this case as well as in the second embodiment, a configuration using software may be used.

(Embodiment 4) FIG. 5A shows an oscillation detecting means 26 which is provided with a mask 25 for a certain period of time from the start of the activation state of the magnetron 11 and prohibits oscillation detection during this mask period. It is a block diagram, and the same code | symbol is attached | subjected to the same component as FIG.

In this way, by masking the period in which the noise is relatively likely to be generated, such as the start of the starting state of the magnetron 11, it is possible to prevent the noise from being erroneously switched to the oscillation state. Also in this case,
A configuration using software may be used as shown in FIG.

(Embodiment 5) In FIG. 6A, an operation mode of steady (I) 30 is inserted at the beginning of steady 29 with respect to three operation mode information 18 of stop 27, start 28 and steady 29. 6B is a configuration diagram of the operating mode information creating unit 31, FIG. 6B is a diagram showing a schematic timing of the control signal 19 and the current information 13, and FIG. 7 is a configuration diagram when software is used. Is.

By this steady state (I), it is possible to clearly indicate to the high-voltage power supply circuit 1 that the operation mode has been switched from the startup to the steady state.

(Sixth Embodiment) FIG. 8A shows the operation mode information 18 of the steady (I) 32.
Is a configuration diagram of the operation mode information creating means 33 configured to switch according to the high frequency output set value 16, and FIG. 8B is a configuration diagram when software is used.

With this configuration, the operation mode information 18 of the steady (I) 32 can be brought closer to the value of the output setting information 17 used in the steady state, so that the steady (I) 32 can be smoothly switched to the steady 29. You can

(Embodiment 7) FIG. 9A shows an operation mode in which the operation mode information 18 of the steady (I) 32 is further divided into a steady (I-1) 34 and a steady (I-2) 35 and inserted. FIG. 9 is a configuration diagram of the information creating means 36, and FIG. 9B is a diagram showing its timing.

After this steady (I-1) 34, a steady (I-1)
-2) With the configuration of inserting 35, the steady (I-1) 34
Can be specialized to indicate that the operation mode switches from the startup 28 to the steady state 29, so that this switching can be clearly shown to the high-voltage power supply circuit 1.

(Embodiment 8) FIG. 10 shows a configuration in which the operation mode information 18 of the steady (I-2) 37 inserted after the steady (I-1) 34 is switched according to the high frequency output set value 16. It is a block diagram of the operation mode information creating means 38, and the same components as those in FIG. 9 are designated by the same reference numerals.

With this structure, the operation mode information 18 of the steady (I-2) 37 is used as the output setting information 17 used in the steady state.
Since it is possible to approach the value of
The switching to 9 can be clearly shown to the high-voltage power supply circuit 1, and the startup 28 can be smoothly switched to the steady state 29.

(Embodiment 9) FIG. 11A shows the control signal 19 provided in the power supply control circuit 10 of the high-voltage power supply circuit 1 in the operating state 39 and the stop state 40.
FIG. 4 is a configuration diagram of an operation / stop identification circuit 41 for identifying
FIG. 11B shows the timing.

The operation / stop identification circuit 41 defines the period from the time when the control signal 19 reaches the first level 42 or more to the first level 43 or lower, which is lower than the first level 42, as the operating state 39. For identification, the power supply control circuit operates the high-voltage power supply circuit during this period, and identifies it as the stopped state 40 and stops it during the other period.

In this way, from the stopped state 40 to the operating state 39
Since there is a difference in the identification level of switching from the operating state 39 to the stopped state 40 when switching to
The stop identification circuit 10 can reliably identify the stop and the operation.

(Embodiment 10) FIG. 12 shows the configuration of an activation identifying circuit 45 for identifying the control signal 19 as an activation state 44 and the operation of the power source control circuit 10 provided in the power source control circuit 10 of the high voltage power source circuit 1. Figure, Figure 1
3 is a diagram showing the timing of the control signal 19 and the output set value 46 input to the drive circuit 7 at that time, and the same components as those in FIG. 1 are designated by the same reference numerals.

The activation identification circuit 45 starts the third level 4 from the time when the control signal 19 reaches the first level 42 or higher.
The period until reaching 7 or more is identified as the activation state 44, and during this period, the power supply control circuit 10 outputs the output set value 46 obtained by adding the activation set value 48 to the control signal 19 input from the system control circuit 15. It is configured to be sent to.

As described above, by adding the start set value 48, the ON ratio of the drive pulse of the semiconductor switching element 6 can be increased, and sufficient electric power can be supplied to the heater of the magnetron 11.

Therefore, the start-up time of the magnetron 11 can be shortened in the start-up state 44 in which the control signal 19 which is held down to the third level 47 or lower to indicate the start-up 28 is input.

(Embodiment 11) FIG. 14 shows the voltage limiter circuit 9 when the control signal 19 is identified as the activation state 44.
FIG. 15 is an operation diagram of the power supply control circuit 10 and a configuration diagram of the voltage limiter circuit 9 configured to operate the same. FIG. 15 is an operation waveform diagram thereof, and the same components as those in FIG. .

Since the voltage limiter circuit 9 detects the voltage of the semiconductor switching element 6 and attenuates the output set value 50 when the voltage exceeds the set value 49, the semiconductor switching in the activated state is performed. The voltage of the element 6 can be limited to around the set value 49. Therefore,
Since the voltage applied to the magnetron 11 in the activated state 44 is controlled to be substantially constant, it is possible to prevent the excessive voltage application to the magnetron 11.

(Embodiment 12) FIG. 16 shows a steady state discrimination circuit 52 provided in the power source control circuit 10 of the high voltage power source circuit 1 for discriminating the control signal 19 from the steady state 51 and the control operation of the power source control circuit 10 at that time. It is a figure shown, and the same code | symbol is attached | subjected to the same component as FIG.

This steady identification circuit identifies the period from the time when the control signal 19 reaches the third level 47 or higher until it reaches the second level 43 or lower as the steady state 51, and the power supply control circuit 10 determines this period. Is configured to send the control signal 19 input from the system control circuit to the drive circuit 7 as the output set value 46.

Since the difference between the start and end identification levels of the steady state 51 is set in this manner, the steady identification circuit 52 can reliably identify the steady state 51.

Further, the system control circuit 15 uses a wide range from a fourth level 53 (details will be described later) to a second level 43, which is sufficiently higher than the third level 47, as shown in FIG. Since the output setting information 17 of the steady state 29 can be finely set, stable power control becomes possible.

(Embodiment 13) FIG. 18 shows an abnormality identifying circuit 55 provided in the power supply control circuit 10 of the high-voltage power supply circuit 1 for identifying the control signal 19 as an abnormal state 54, and the operation of the power supply control circuit 10 at that time. It is a figure, and the same code | symbol is attached | subjected to the same component as FIG.

The abnormality discriminating circuit 55 discriminates the abnormal state 54 when the control signal 19 reaches the fourth level 53 or higher, which is sufficiently higher than the third level 47, and the power supply control circuit 10 receives this. The high voltage power supply circuit 1 is configured to stop.

In this way, the control signal 19 changes to the fourth level 5
Reaching 3 indicates that normal power control is not performed because the device is out of the original setting range.

Therefore, since this is detected and the high-voltage power supply circuit 1 is stopped, it is possible to prevent a circuit failure due to a power control abnormality.

(Embodiment 14) FIG. 19 shows a control signal 19 input to the power supply control circuit 10.
On the other hand, it is a diagram showing a high voltage power supply circuit 1 configured to input an output set value 57 through which a control signal 19 is passed through a filter circuit 56 to a drive circuit 7, and the same components as those in FIG. The symbol is attached.

With such a configuration, the control signal 19 is filtered and the output set value 5 is changed smoothly.
7, and the signal is input to the drive circuit 7 and converted into a pulse signal to be applied to the semiconductor switching element 6, so that the operation mode information 18 of the control signal 19 is supplied to the power of the high voltage power supply circuit 1 and the high frequency output of the magnetron 11. The abrupt change due to the multiplexing of is not transmitted, and noise is also removed by this filtering process.

Further, the power supply control circuit 10 has a rapid change in the control signal 19 (indicating a change in the operation mode information 18).
Is input as it is, so it is in the stopped state 40, the activated state 4
4. The operation mode of the steady state 51 is surely identified, and the switching of the operation mode of the high-voltage power supply circuit 1 can be quickly followed by the change.

[0076]

As described above, according to the present invention, the system control circuit multiplexes the output mode information for increasing / decreasing so that the current information of the high-voltage power supply circuit matches the high frequency output setting value, and the operation mode information, Since it is configured to be sent to the high voltage power supply circuit, there is an effect that this control signal transmission path can be simplified.

Further, the oscillation detecting means included in the system control circuit switches the magnetron from the starting state to the oscillating state in which the time required to reach the oscillating state is not determined, and the input current information reaches the first oscillation detecting level. The system control circuit does not need a special signal for oscillation detection because it is configured to discriminate based on the increase, and has the effect that it can reliably follow the magnetron state and switch to the steady state. .

Further, by setting the oscillation detection level for judging the switching of the magnetron from the starting state to the oscillating state according to the high frequency output set value, it is possible to improve the noise resistance characteristic at the time of high high frequency output which is generally used. Have an effect.

Further, by providing a mask for a fixed time from the start of the magnetron start-up state and prohibiting oscillation detection during this mask period, the start-up of the magnetron start-up period is relatively easy to generate noise. In addition, there is an effect that it is possible to prevent accidental switching to the oscillation state.

By inserting the steady (I) operation mode at the beginning of the steady state, it is possible to clearly indicate to the high-voltage power supply circuit that the operating mode has been switched from the startup to the steady state.

Further, by arranging the control signal in the steady (I) operation mode to be switched according to the high frequency output setting value, there is an effect that the steady I can be switched to the steady state smoothly.

The steady (I) operation mode is further divided into a steady (I-1) and a steady (I-2), and the steady I
-2 is different from the stationary I-1 in the discrimination level and
Insert after steady I-1 and switch from startup to steady
By smoothing the voltage, there is an effect that this switching can be clearly shown to the high-voltage power supply circuit.

Further, by arranging the control signal in the steady (I-2) operation mode to be switched according to the high frequency output set value, the electric power applied to the magnetron can be made smoother up to the high frequency output set value. It has the effect that it can be launched.

Further, the operation / stop identification circuit provided in the power supply control circuit of the high-voltage power supply circuit is configured to provide a difference in the identification level of switching from the stopped state to the operating state and switching from the operating state to the stopped state. By doing so, the power supply control circuit has an effect of surely distinguishing the stop and the start.

Further, the activation identification circuit provided in the power supply control circuit of the high voltage power supply circuit identifies the period from the time when the control signal reaches the first level or higher to the third level or higher as the startup state, During this period, the power supply control circuit can supply sufficient power to the magnetron heater by configuring it so that the output set value obtained by adding the start set value to the control signal input from the system control circuit is sent to the drive circuit. It has the effect of shortening the startup time.

The high-voltage power supply circuit is a semiconductor switching device.
Comprising a voltage limiter circuit for limiting the voltage of the device, the power supply control circuit, the control signal is configured to operate the electric <br/> voltage limiter circuit when showing the starting state, excessive to the magnetron It has the effect of preventing voltage application.

Further, the steady discrimination circuit provided in the power supply control circuit of the high voltage power supply circuit has a third discrimination level for discriminating the start of the steady state of the control signal and a second discrimination level for discriminating the end of the steady state. Since the difference is provided, the steady state can be reliably identified. Further, since the output setting information in the steady state can be set in a wide range from the fourth level to the second level, which is sufficiently higher than the third level, it has an effect of enabling stable power control.

Further, the abnormality discriminating circuit provided in the power supply control circuit of the high-voltage power supply circuit discriminates an abnormal state when the control signal leaves the original setting range and reaches the fourth level or higher, and stops the high-voltage power supply circuit. Therefore, there is an effect of preventing a circuit failure due to an abnormal power control.

Further, since the control signal is filtered and input to the drive circuit, a sudden change due to the multiplexing of the operation mode information of the control signal is not transmitted to the power of the high voltage power supply circuit and the high frequency output of the magnetron. Have an effect. Furthermore, since abrupt changes in the control signal, that is, changes in the output setting information and operation mode information, are directly input to the power supply control circuit, the operation mode can be reliably identified and the operation mode of the high-voltage power supply circuit can be switched. Has the effect of being able to quickly follow the change.

[Brief description of drawings]

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

FIG. 2 is an explanatory diagram of a control signal of the present invention.

FIG. 3A is a configuration diagram of an oscillation detecting unit according to a second embodiment of the present invention, and FIG. 3B is a flowchart when the oscillation detection is performed by software.

FIG. 4 is a configuration diagram of oscillation detecting means according to a third embodiment of the present invention.

FIG. 5 is a configuration diagram of oscillation detecting means according to a fourth embodiment of the present invention.

FIG. 6 is a configuration and timing chart of an operation mode creating unit according to a fifth embodiment of the present invention.

FIG. 7 is a block diagram when the same operation mode is created by software.

FIG. 8 is a configuration diagram when the same operation mode creating means is performed by software.

FIG. 9 is a configuration and timing chart of an operation mode creating unit according to a seventh embodiment of the present invention.

FIG. 10 is a configuration diagram of operation mode creating means according to a seventh embodiment of the present invention.

11A is a configuration diagram of an operation / stop identification circuit 41 according to a ninth embodiment of the present invention, and FIG. 11B is the same timing diagram.

FIG. 12 is a configuration of a start discrimination circuit according to a tenth embodiment of the present invention,
Diagram showing the operation of the power supply control circuit and the timing with the control signal output set value

FIG. 13 is a diagram showing a timing of the control signal and an output set value input to the drive circuit.

FIG. 14 is an operation diagram of a power supply control circuit in a startup state and a configuration diagram of a voltage limiter circuit according to an eleventh embodiment of the present invention.

FIG. 15 is the same waveform diagram.

FIG. 16 is an operation diagram of a power supply control circuit in a steady state according to a twelfth embodiment of the present invention and a configuration diagram of a steady identification circuit.

FIG. 17 is a diagram showing a setting range of the output setting information.

FIG. 18 is an operation diagram of a power supply control circuit in an abnormal state and a configuration diagram of an abnormality identification circuit according to a thirteenth embodiment of the present invention.

FIG. 19 is a configuration diagram of a power supply control circuit according to a fourteenth embodiment of the present invention and an operation waveform diagram of control signals and output set values.

FIG. 20 is a configuration diagram of a high-frequency heating device according to a first conventional example.

FIG. 21 is a waveform diagram of the semiconductor switching element of the conventional example.

FIG. 22 is a configuration diagram of a high-voltage power supply circuit of a high-frequency heating device according to a second conventional example.

FIG. 23 is a waveform chart of each part of the conventional example.

[Explanation of symbols]

1 High-voltage power supply circuit 2 Commercial power supply 3 DC power supply 4 Leakage type transformer 5 capacitors 6 Semiconductor switching element 7 drive circuit 8 Rectifier circuit 9 Voltage limiter circuit 10 Power control circuit 11 magnetron 13 Current information 14 Current information transmission path 15 System control circuit 16 High frequency output setting value 17 Output setting information 18 Operation mode information 19 Control signal 20 Control signal transmission path 21, 24, 26 Oscillation detection means 22, 23 Oscillation detection level 25 masks 27 stop 28 Start 29 Stationary 30, 32 Stationary (I) 31, 33, 36, 38 Operation mode information creating means 34 Stationary (I-1) 35, 36 Stationary (I-2) 39 Operating state 40 stopped 41 Operation / stop identification circuit 42 First Level 43 Second Level 44 Starting state 45 Start-up identification circuit 46 Output setting value 47 Third Level 48 Start setting value 49 set value 50, 57 Output setting value 51 steady state 52 Stationary discrimination circuit 53 Fourth Level 54 Abnormal state 55 Abnormality discrimination circuit 56 Filter circuit

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshiro Ishio 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Kenji Yasui 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. (56) Reference JP-A-7-245963 (JP, A) JP-A-3-204518 (JP, A) JP-A-8-8056 (JP, A) JP-A-6-68973 (JP, A) JP-A-5-129074 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H05B 6/68

Claims (14)

(57) [Claims] 1. A system control circuit, a high-voltage power supply circuit,
A magnetron connected to the high-voltage power supply circuit, a current information transmission path for transmitting input current information of the high-voltage power supply circuit to the system control circuit, and a control signal transmission path for transmitting a control signal from the system control circuit to the high-voltage power supply circuit. The high-voltage power supply circuit includes a DC power supply obtained by rectifying a commercial power supply, a leakage type transformer connected to the DC power supply, and a capacitor connected to a first winding of the leakage transformer. A resonance circuit configured, a semiconductor switching element connected to the first winding of the leakage transformer, a drive circuit that creates a pulse signal for driving the semiconductor switching element from an output set value, and a leakage transformer Rectifier circuit connected to the secondary side
And the output setting value sent to the drive circuit from the control signal
An output setting that is made up of a power supply control circuit that switches operation modes such as stop, start, and steady state of the magnetron, and the system control circuit controls the input current information to be a value commensurate with the high frequency output setting value. The power supply control circuit outputs the control signal in which information and operation mode information are multiplexed.
High frequency heating device configured to send to. 2. The high frequency heating apparatus according to claim 1, wherein the system control circuit has an oscillation detection means for comparing the input current information and a determination level to determine that the magnetron has switched from a starting state to an oscillating state. 3. The determination level is set according to the high frequency output set value.
It switches El high-frequency heating apparatus according to claim 2, wherein. Wherein the predetermined time from the start of the activation state high-frequency heating apparatus according to claim 2, further comprising a masking means for masking the oscillation detection means. 5. The operation mode information includes stop, start, steady I,
Switches to stationary, the stationary I is the discrimination level is the constant
Different from usual and inserted at the beginning of the above steady, from start to steady
The high-frequency heating device according to claim 1 , wherein the switching to is clearly defined . 6. The high-frequency heating device according to claim 5, wherein the output setting information during the period of steady I is switched according to the high-frequency output setting value. 7. The stationary I period is divided into at least a stationary I-1 and a stationary I-2, and the stationary I-2 has a discrimination level.
Different from the stationary I-1 and inserted after the stationary I-1.
The high-frequency heating device according to claim 5 , which is turned on to smoothly switch from startup to steady . 8. The high-frequency heating device according to claim 7, wherein the output setting information in the period of steady I-2 is switched according to the high-frequency output setting value. 9. The power supply control circuit identifies the operation mode information as an operation state from the time when the control signal reaches the first level or higher until it reaches the second level which is lower than the first level. The high-frequency heating device according to claim 1, wherein the high-voltage power supply circuit is operated and the high-voltage power supply circuit is stopped during another period of time by identifying the stopped state. 10. The power supply control circuit discriminates the operation mode information from the activation state from the time when the control signal reaches the first level or higher until it reaches the third level or higher, and sets the activation setting to the control signal. The high frequency heating device according to claim 1, wherein the output set value added with the value is sent to the drive circuit. 11. A high voltage power supply circuit is a semiconductor switching device.
Comprising a voltage limiter circuit for limiting the voltage of the device, the power supply control circuit for a period which is identified as start state activates said voltage limiter circuit, a high frequency according to claim 1, wherein the structure for controlling the voltage applied to the magnetron Heating device. 12. The power supply control circuit discriminates the operation mode information as a steady state from the time when the control signal reaches the third level or higher until it reaches the second level or lower, and sets the output of the control signal. Claim 1 of the composition sent to a drive circuit as a value
The high-frequency heating device described. 13. The high frequency heating apparatus according to claim 1, wherein the power supply control circuit stops the operation when the control signal reaches a fourth level or higher. 14. The high-frequency heating device according to claim 10, wherein the power supply control circuit uses a signal obtained by filtering the control signal as an output set value.