JPH0744894B2 - Heating cooker - Google Patents

Description

TECHNICAL FIELD The present invention relates to a cooking device using induction heating.

2. Description of the Related Art In recent years, a heating cooker using induction heating has been required to be able to cook without being affected by an abnormal operation caused by a single impulse-like power supply noise.

A conventional cooking device using this type of induction heating is equipped with a protective function device such as an abnormal load detection device, temperature detection device or overvoltage or low voltage detection device, and the heating display LED is turned on during normal heating. Then, when the protection function device operates, heating is stopped once, the heating display LED is turned off for a certain period while heating is stopped, and then heating is restarted, but at this time, the protection function device is deactivated. If not, stop heating again, and while heating is stopped, LE for heating display
D was turned off for a certain period of time.

If the operation of the protective function device is released when the heating is restarted, the normal heating state is restored and the heating display LED is turned on again.

Problems to be Solved by the Invention In such a conventional cooker, the LED lights only when heating is in progress, but when the protective function device is activated, heating must be stopped and started repeatedly at fixed time intervals. Also, there was a problem that the LED also turned off and on repeatedly.

The present invention solves the above-mentioned problems, and always monitors the state of the inverter circuit and notifies the abnormality only when the abnormal state continuously occurs for a certain period of time or longer, and is caused by a common impulse noise such as a power supply noise. The first object is to eliminate the meaningless appeal to the user, which does not affect the cooking performance, by not displaying the abnormal motion with respect to the abnormal motion.

Also, the state of the inverter circuit is constantly monitored, and heating is forcibly stopped for a certain period of time (for example, about 8 seconds) only when an abnormal state occurs continuously for a certain period of time or more, and the abnormality is notified during that period, thus eliminating wasteful use. A second object is to prevent power consumption and to reliably appeal an abnormality only in an abnormal state that affects cooking performance.

Means for Solving the Problems In order to achieve the first object of the present invention, a heating coil that induction-heats a container, an inverter circuit that supplies a high-frequency current to the heating coil, and a heating state of the container are notified. A notifying means, an abnormality detection circuit that detects an abnormal state of the inverter circuit and outputs a signal, and a signal when the output of the abnormality detection circuit is not canceled within a fixed time after the abnormality detection circuit outputs a signal. And a timer circuit that outputs a signal, and the notification means notifies the abnormal state until the signal of the abnormality detection circuit is released after receiving the output signal of the timer circuit. As a means.

Further, in order to achieve the second object, in addition to the first problem solving means, a prohibition circuit that receives the output signal of the timer circuit and prohibits the oscillation of the inverter circuit for a predetermined time is provided.
A second problem solving means is to notify the abnormal state by the notification means while the prohibition circuit prohibits the oscillation of the inverter circuit.

Effect The present invention detects abnormalities when the operating state of the inverter circuit is abnormal due to the large fluctuation of the power supply voltage, abnormal oscillation of the inverter circuit, abnormal heating of parts, improper pot, etc. by the first means for solving the problems described above. When the circuit operates and the timer circuit operates by the signal from the abnormality detection circuit, and the signal is output from the abnormality detection circuit for a certain period of time or more, the timer circuit outputs a signal to the notification means and the notification means is a lighting element. Blinking or an alarm etc. informs the user of the abnormality by warning the equipment abnormality until the operating condition of the inverter circuit becomes normal and the signal from the abnormality detection circuit is released. After that, the inverter circuit is brought into a state in which it can oscillate again and the above contents are repeated.

Further, according to the second problem solving means, when the signal is output from the abnormality detection circuit for a predetermined time or longer, the timer circuit outputs a signal to the prohibition circuit, and the prohibition circuit forcibly oscillates the inverter circuit for a predetermined time. It is stopped (for about 8 seconds).
During this time, the notifying means warns the user of the abnormality by blinking the lighting element, alarming the device, or the like. After that (after about 8 seconds), the inverter circuit can be oscillated again, and the above contents are repeated.

Embodiment An embodiment of the first invention will be described below with reference to FIGS. 1 and 2.

In FIG. 1, an inverter circuit 2 is connected to a commercial power supply 1. The inverter circuit 2 includes a rectifier 3 connected to the commercial power supply 1, a capacitor 4 connected to the output terminal of the rectifier 3, a choke coil 5 and a smoothing capacitor 6 connected in series, and a resonance capacitor 7 connected to the smoothing capacitor 6. It is composed of a switching transistor 8 including a diode connected in antiparallel. Capacitor 4
The choke coil 5 and the choke coil 5 form a filter circuit. The heating coils 9 and 10 are connected in parallel with the resonance capacitor 7 to form a resonance circuit. The control circuit 11 is
An abnormality detection circuit 12 that detects an abnormal state of the inverter circuit 2 by detecting the voltage across the smoothing capacitor 6, an oscillation stop circuit 13 that stops the oscillation of the inverter circuit 2 by the output signal of the abnormality detection circuit 12, and an abnormality detection The time when the inverter circuit 2 is in an abnormal state is measured by the output signal of the circuit 12, and when the abnormal state continues for a certain time or longer, the timer circuit 14 that outputs a signal and the switching transistor
And a drive circuit 15 for driving the.

In this embodiment, the timer time before the timer circuit 14 measures the abnormal time of the inverter circuit 2 and outputs a signal is about 4 seconds. The abnormality detection circuit 12 may detect the abnormal state of the inverter circuit 2 by detecting the voltage across the resonance capacitor 7 or the switching transistor 8.

Next, in FIG. 2, a storage unit 18 for storing a pot 17 that is a container for rice is provided inside the main body 16, and an upper lid 19 covers the upper portion of the main body 16 so that the pot 17 can be opened and closed. By doing so, it can be taken out. Heating coil 9,
Reference numeral 10 is for induction heating a pot 17, which is placed on a support 20, and a plurality of ferrite cores 21 that absorb leakage magnetic flux are radially provided below the support 20. The load detection device 22 moves up and down and mechanically detects whether or not the pan 17 is a proper container for cooking rice.It is provided on the lower surface of the pan 17 and the pan 17 is not suitable for cooking. For example, it outputs to the control circuit 11 a signal that the pot 17 is improper. Control circuit 11
Controls the oscillation of the inverter circuit 2 and
It also controls the display unit 23, which is a notifying means for notifying the heating state of the pan 17 provided at the upper part of the table.

The operation of the above configuration will be described. When rice and water are put in the pan 17 and rice cooking is started, the control circuit 11 turns on the rice cooking LED of the display unit 23, and the inverter circuit 2 starts oscillating.
When a voltage abnormality occurs in the commercial power supply 1 during rice cooking and a voltage higher than the abnormality is input to the inverter circuit 2, a high voltage is applied to both ends of the smoothing capacitor 6. As a result, since the power supply voltage of the abnormality detection circuit 12 is abnormal, the inverter circuit 2
Is determined to be an abnormal state, and signals are output to the oscillation stop circuit 13 and the timer circuit 14, respectively. Here the oscillation stop circuit
13 outputs a signal to the drive circuit 15 so as to stop the operation of the switching transistor 8, and the drive circuit 15 stops the operation of the switching transistor 8. Then, the abnormality detection circuit 12 continues to output a signal until the voltage of the commercial power supply 1 becomes normal. At this point, the rice cooking LED remains lit.

Then, the timer circuit 14 operates the timer as an abnormal state of the inverter circuit 2. However, when this abnormal state recovers within 4 seconds, the abnormality detection circuit 12 releases the output signal from that point, and the drive circuit 15 Is driven, the inverter circuit 2 is oscillated, and the timer of the timer circuit 14 is reset.

On the contrary, when the abnormal state of the inverter circuit 2 does not recover within 4 seconds, the timer circuit 14 recovers from the abnormal state from that point until the output signal from the abnormality detection circuit 12 is released.
The signal is output to the display unit 23. While receiving the signal from the timer circuit 14, the display unit 23 blinks the rice cooking LED at 0.5 second intervals.

Thus, according to the heating cooker of the first embodiment of the present invention,
If the abnormal state of the inverter circuit 2 continues for a certain time (4 seconds) or more, the rice cooker LED blinks at 0.5 second intervals until the abnormal state is restored by the control circuit 11 to notify the user of the abnormal state. Therefore, the operation of the inverter circuit 2 is immediately stopped with respect to a single impulse-like noise, but the normal operation is restarted after the abnormal state of the inverter circuit 2 is recovered. Do not notify the user each time because it will not be affected. Although the abnormality detection circuit 12 detects the abnormal voltage of the commercial power supply 1 and detects the abnormal state of the inverter circuit 2 in the above embodiment, the invention is not limited to this. For example, it is not suitable for cooking. The load detection device 22 for detecting the pot 17 or the abnormal temperature rise of the components of the inverter circuit 2 (not shown) may be detected. Further, in the above-described embodiment, the notification means (display unit) 23 is a rice cooking LED and is configured to notify the abnormality by blinking. However, the same effect can be obtained even if the abnormality is notified by a buzzer or the like.

Next, an embodiment of the second invention will be described with reference to FIG. The same components as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted. The control circuit 24 detects an abnormal state of the inverter circuit 2 by detecting the voltage across the smoothing capacitor 6, and an oscillation stop circuit that stops the oscillation of the inverter circuit 2 by the output signal of the abnormality detection circuit 12. 13 and the output signal of the abnormality detection circuit 12, the time during which the inverter circuit 2 is in an abnormal state is measured, and when the abnormal state continues for a certain time or more, a signal is sent to the inhibition circuit 25 that inhibits the operation of the inverter circuit 2 for a certain time. A timer circuit 14 for outputting and a drive circuit 15 for driving the switching transistor 8 are provided.

In this embodiment, the prohibiting circuit 25 is the inverter circuit 2
The prohibition time for prohibiting the oscillation is about 8 seconds, and the timer time until the timer circuit 14 measures the abnormal time of the inverter circuit 2 and outputs a signal is about 4 seconds.

The operation of the above configuration will be described. When rice and water are put in the pan 17 and rice cooking is started, the control circuit 11 turns on the rice cooking LED of the display unit 23, and the inverter circuit 2 starts oscillating.
When a voltage abnormality occurs in the commercial power supply 1 during rice cooking and a voltage higher than usual is input to the inverter circuit 2, a high voltage is applied to both ends of the smoothing capacitor 6. As a result, the abnormality detection circuit 12 determines that the inverter circuit 2 is in an abnormal state because the power supply voltage is abnormal, and outputs signals to the oscillation stop circuit 13 and the timer circuit 14, respectively. Here the oscillation stop circuit
13 outputs a signal to the drive circuit 15 so as to stop the operation of the switching transistor 8, and the drive circuit 15 stops the operation of the switching transistor 8. Then, the abnormality detection circuit 12 continues to output a signal until the voltage of the commercial power supply 1 becomes normal. At this point, the rice cooking LED remains lit.

Then, the timer circuit 14 operates the timer as an abnormal state of the inverter circuit 2. However, when this abnormal state recovers within 4 seconds, the abnormality detection circuit 12 releases the output signal from that point, and the drive circuit 15 Is driven, the inverter circuit 2 is oscillated, and the timer of the timer circuit 14 is reset.

Conversely, when the abnormal state of the inverter circuit 2 does not recover within 4 seconds, the timer circuit 14 outputs a signal to the prohibition circuit 25 and resets the timer. And the prohibition circuit
25 prohibits the operation of the inverter circuit 2 for 8 seconds. This 8
Only for a second, the control circuit 24 blinks the rice cooking LED of the display unit 23 in 0.5 second steps. After 8 seconds, the prohibition is released, the inverter circuit 2 is made ready to oscillate again, and the abnormality detection circuit 12 detects the abnormal state of the inverter circuit 2.

Thus, according to the heating cooker of the second embodiment of the present invention,
If the abnormal condition of the inverter circuit 2 continues for 4 seconds or more, the control circuit 24 forcibly prohibits the operation of the inverter circuit 2 for about 8 seconds to prevent unnecessary power consumption, and the rice cooking LED blinks at 0.5 second intervals during this period. Then, the user is surely notified of the abnormality. Therefore, the operation of the inverter circuit 2 is immediately stopped for a single impulse-like noise, but the normal operation is restarted after the abnormal state of the inverter circuit 2 is recovered, so that the rice cooking performance is completely affected. There is not, so do not notify the user each time. Although the abnormality detection circuit 12 detects the abnormal voltage of the commercial power supply 1 and detects the abnormal state of the inverter circuit 2 in the above-described embodiment, the invention is not limited to this. In addition, an improper pan 17 may be detected, or an abnormal temperature rise of parts of the inverter circuit 2 may be detected. Further, in the above embodiment, the notification means (display unit)
Although 23 is a rice cooking LED and is configured to notify the abnormality by blinking, the same effect can be obtained even when the abnormality is notified by a buzzer or the like.

EFFECTS OF THE INVENTION As is apparent from the above description of the embodiments, according to the first invention, the user is notified of the abnormality only when the abnormal state of the inverter circuit occurs continuously for a certain period of time. It is possible to prevent repeated meaningless notifications to the user with respect to static noise. Further, according to the second aspect of the invention, when the abnormal state of the inverter circuit occurs continuously for a certain period of time, the heating is forcibly stopped for a certain period of time and the abnormality is notified during that period, so that wasteful power consumption can be prevented. Further, it is possible to reliably notify the user of the abnormality.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a heating cooker according to an embodiment of the present invention, and FIG.
FIG. 3 is a vertical sectional view of the heating cooker, and FIG. 3 is a circuit diagram of a heating cooker according to another embodiment of the present invention. 2 ... Inverter circuit, 9 ... Heating coil, 10 ... Heating coil, 12 ... Abnormality detection circuit, 14 ... Timer circuit, 17
…… Pot (container), 23 …… Display (notification means).

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shigeo Hamaoka 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References

Claims (2)

[Claims] 1. A heating coil for inductively heating a container, an inverter circuit for supplying a high-frequency current to the heating coil, a notifying means for notifying a heating state of the container, and an abnormal condition of the inverter circuit for detecting a signal. The abnormality detection circuit for outputting, and a timer circuit for outputting a signal when the output of the abnormality detection circuit is not canceled within a fixed time after the abnormality detection circuit outputs a signal, the notifying means includes the timer circuit. After receiving the output signal from the heating cooker, the abnormal state is notified until the signal from the abnormality detection circuit is released. 2. A prohibiting circuit for prohibiting the oscillation of the inverter circuit for a certain period of time in response to an output signal of the timer circuit, and an alarming means for notifying an abnormal state while the prohibiting circuit prohibits the oscillation of the inverter circuit. Claim 1
The cooker described.