JP2007289304A - Rice cooker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rice cooker which correctly performs a circuit operation when a power supply voltage declines and does not give loads to a circuit element in the rice cooker provided with a DC power source for an operation obtained from a commercial power source. <P>SOLUTION: An inner pot 1 is freely detachably housed inside a rice cooker main body 2 whose upper surface is opened, the inner pot 1 is induction-heated by a heating coil 3, and single direction power 4 obtained by rectifying the commercial power source 5 is converted to high frequency power by an inverter circuit 9 comprising a switching element 8, a resonance capacitor 7 and a smoothing circuit 6. By controlling a driving means 10 for driving the switching element 8 by a control means 11, induction heating when cooking rice and when insulating heat or the like is controlled. An operation current is supplied from a power circuit 20 to respective parts of the circuit, and when a detection voltage detected by a voltage detection means 21 for detecting the voltage of the commercial power source 5 is equal to or lower than a fixed voltage, the induction heating is stopped by a first stop means 22. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a rice cooker having a DC power supply for operation obtained from a commercial power supply.

  In general, home appliances produce a DC power supply for operation from a commercial power supply. In recent years, a single-chip power supply IC or the like has made it possible to create a DC power supply circuit in a space-saving manner. In addition, energy saving by switching the power source has been performed (for example, see Patent Document 1).

FIG. 9 is a block diagram of a conventional rice cooker. In FIG. 9, the inner pot 1 is installed in the rice cooker body 2, and the inner pot 1 is induction-heated by the heating coil 3. The unidirectional power supply 4 is obtained by rectifying the alternating current supplied from the commercial power supply 5. High frequency power for induction heating is generated by an inverter circuit 9 including a smoothing capacitor 6, a resonance capacitor 7, and a switching element 8 based on the unidirectional power supply 4. The driving means 10 drives the inverter circuit 8. The cooking means in the inner pot 1 is heated and cooked by controlling the driving means 10 at the time of cooking rice or keeping warm by the control means 11. The power supply circuit 12 is supplied with power from the commercial power supply 5 and generates power for circuit operation. The power of the driving means 10 is supplied from the power supply circuit 12, and heating is not performed during standby when rice cooking or heat insulation is not performed. Therefore, power supply to the driving means 10 is stopped by the power stop means 13, and power consumption during standby is Is trying to reduce.
JP 2000-287837 A

  However, in such a conventional configuration, the power supply voltage becomes unstable when the AC voltage of the commercial power supply 5 is low or the voltage drops during a power failure, and erroneous detection of input or induction heating becomes unstable, resulting in a circuit. There was a problem that a load was applied to the element.

  SUMMARY OF THE INVENTION The present invention solves the above-described conventional problems, and an object thereof is to provide a rice cooker that correctly performs a circuit operation when a power supply voltage drops and does not apply a load to a circuit element.

  In order to achieve the above object, the present invention is an inverter having a switching element, a resonant capacitor, and a smoothing circuit in which an inner pot is detachably housed in a rice cooker body having an open upper surface, and the inner pot is induction-heated by a heating coil. A unidirectional power source obtained by rectifying a commercial power source by a circuit is converted into high-frequency power, and a driving unit that drives a switching element is controlled by a control unit to control induction heating at the time of rice cooking or heat retention, etc. When the detection voltage detected by the voltage detection means for detecting the voltage of the commercial power supply is below a certain voltage, the induction heating is stopped by the first stop means.

  As a result, induction heating can be prohibited when the power supply voltage is unstable due to low AC voltage of the commercial power supply, such as when the commercial power supply voltage drops or during a power failure, and the circuit operates correctly and overloads the circuit elements. Can not be given.

  The rice cooker of the present invention can correctly perform circuit operation even during a power failure or a sudden voltage drop, and can prevent a load from being applied to circuit elements.

  The first invention is obtained by rectifying a commercial power source, a rice cooker body having an open upper surface, an inner pot detachably accommodated in the rice cooker body, a heating coil for induction heating the inner pot, and the like. A unidirectional power source, a switching element, a resonance capacitor, an inverter circuit that has a smoothing circuit and converts the unidirectional power source into high-frequency power, a driving unit that drives the switching element, and rice cooking by controlling the driving unit Control means for controlling induction heating at the time of heat insulation or the like, a power supply circuit for supplying an operating current to each part of the circuit, a voltage detection means for detecting the voltage of the commercial power supply, and a detection voltage detected by the voltage detection means is a constant voltage In the following cases, it is equipped with a first stopping means that stops induction heating. When the power supply voltage is unstable due to a low AC voltage of the commercial power supply such as when the commercial power supply voltage drops or during a power failure, induction Can be prohibited, correctly it performs circuit operation, it so as not to overload the circuit elements.

  According to a second aspect of the present invention, in the first aspect of the present invention, the first input unit that performs normal operation only when supplied from the power supply circuit is provided, and the detection voltage detected by the voltage detection unit is used instead of the first stop unit. Is provided with second stopping means for prohibiting input from the first input means to the control means when the voltage is below a certain voltage, and the power supply voltage is unstable due to the low AC voltage of the commercial power supply. Can prevent erroneous input.

  According to a third invention, in the first invention, in place of the first stop means, a third stop for stopping the induction heating for a fixed time after the detection voltage detected by the voltage detection means becomes a constant voltage. Providing a means to prevent induction heating while the voltage is unstable by prohibiting induction heating for a certain period of time until the level stabilizes even if the AC voltage of the commercial power supply becomes a certain voltage Therefore, the circuit operation can be performed correctly and the circuit element can be prevented from being overloaded.

  In a fourth aspect based on the second aspect, in place of the second stop means, the first input means controls the control means for a certain time after the detection voltage detected by the voltage detection means becomes a constant voltage. A fourth stopping means for prohibiting input is provided, and even if the AC voltage of the commercial power supply becomes a certain constant voltage, the input from the first input means is prohibited for a certain period of time until the level is stabilized. Thus, input while the voltage is unstable can be prohibited, and erroneous input can be prevented.

  According to a fifth invention, in the second invention, in place of the second stopping means, a calculation means for performing a calculation based on the output of the first input means and the output from the voltage detection means and outputting the result. And second input means for performing input correction based on the output from the calculation means, and by inputting from the second input means based on the output from the calculation means, the power supply voltage Stable input can be obtained regardless.

  A sixth invention is based on the first input means which performs normal operation only when supplied from the power supply circuit, the output of the first input means and the output from the voltage detection means in the first invention. A calculation means for performing a calculation and outputting a result, and instead of the first stop means, a fifth stop means for stopping induction heating by the output of the calculation means is provided, and the power supply voltage is Induction heating can be performed in a stable state.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 shows a block diagram of the rice cooker according to Embodiment 1 of the present invention, FIG. 2 shows a cross-sectional view of the rice cooker, and FIG. 3 shows a partially block circuit diagram of the rice cooker. .

  As shown in FIGS. 1 and 2, the inner pot 1 is detachably accommodated in the rice cooker body 2, and the inner pot 1 is induction-heated by a heating coil 3. The commercial power source 5 is supplied by the outlet 23, and the unidirectional power source 4 is obtained by rectifying the AC voltage supplied from the commercial power source 5. Based on the unidirectional power supply 4, an inverter circuit 9 including a smoothing capacitor 6, a resonance capacitor 7, and a switching element 8 generates high-frequency power for induction heating. The driving means 10 drives the switching element 8 constituting the inverter circuit 9. The control means 11 controls the drive means 10 at the time of rice cooking or heat retention, and controls induction heating. By this, the food in the inner pot 1 is heated and cooked.

  The power supply circuit 20 generates a DC voltage for circuit driving by the power supplied from the commercial power supply 5. The voltage detection means 21 detects the AC voltage of the commercial power source 5. The first stop means 22 is. The output is input to the control means 11, and the induction heating is stopped when the detection voltage detected by the voltage detection means 21 is below a certain voltage. Note that the circuit board 24 in FIG. 2 performs various controls.

  The operation in the above configuration will be described. In the first stop means 22, the voltage of the commercial power supply 5 detected by the voltage detection means 21 becomes an AC voltage necessary for the power supply circuit 20 to make a voltage that can reliably drive the inverter circuit 9 of the drive means 10. Until this, induction heating is prohibited. As a result, it is possible to prevent a malfunction of the circuit and an overload applied to the circuit element due to a transient voltage change of the power supply circuit 20 due to a power failure or a sudden voltage drop.

  Details of this point will be described with reference to FIG. The microcomputer 25 constitutes the control means 11 and the first stop means 22, and the power supply IC 26 constitutes the power supply circuit 20. The power supply IC 26 is supplied with an AC voltage from the commercial power supply 5, supplies a drive voltage V 1 to the microcomputer 25 and the like, and supplies a drive voltage V 2 to the IH control IC 27 and the drive IC 28 that constitute the drive means 10. In this case, since the IH control IC 27 and the drive IC 28 require higher voltages, V2> V1. Therefore, the IH control IC 27 and the drive IC 28 cannot normally operate depending on the output of the power supply IC 26 when the voltage rises at the time of power failure recovery or the like, but other circuits may operate normally.

  The transistor 29 is supplied with the divided voltage of the AC voltage from the commercial power source 5, and the transistor 29 functions as an emitter follower and inputs the divided value of the AC voltage of the commercial power source 5 to the microcomputer 25. . Until the microcomputer 25 sees the input from the transistor 29 and determines that the voltage V2 generated by the power supply IC 26 is an AC voltage necessary to generate a voltage that can reliably drive the IH control IC 27 and the drive IC 28. By prohibiting induction heating, it is possible to prevent malfunctions of the IH control IC 27 and the drive IC 28 and overloads applied to circuit elements due to a transient voltage change such as a power failure or a sudden voltage drop.

  As described above, in the present embodiment, the first stop unit 22 that stops the induction heating when the detection voltage detected by the voltage detection unit 21 is equal to or lower than a certain voltage is provided. When the power supply voltage is unstable due to the low AC voltage of the commercial power supply 5 such as during a power failure or the like, induction heating can be prohibited, and the circuit operation can be performed correctly so as not to overload the circuit elements.

(Embodiment 2)
FIG. 4 shows a block diagram of the rice cooker according to Embodiment 2 of the present invention.

  As shown in FIG. 4, the first input means 30 is supplied with an operating voltage from the power supply circuit 20 and operates normally only when supplied from the power supply circuit 20. The second stop means 31 prohibits the input from the first input means 30 to the control means 11 when the detection voltage detected by the voltage detection means 21 is below a certain voltage. Other configurations are the same as those of the first embodiment, and the same reference numerals are given and description thereof is omitted.

  The operation in the above configuration will be described. Input is stopped until the detection voltage detected by the voltage detection means 21, that is, the voltage value of the commercial power supply 5 becomes an AC voltage necessary for the power supply circuit 20 to produce a voltage that can reliably operate the first input means 30. By doing so, it is possible to prevent erroneous input due to the output voltage drop of the power supply circuit 20 due to a transient voltage change such as a power failure or a voltage drop.

  As described above, in the present embodiment, the first input unit 30 that operates normally only when supplied from the power supply circuit 20 is provided, and the first detection unit 30 detects when the detection voltage detected by the voltage detection unit 21 is equal to or lower than a certain voltage. Since the second stop means 31 for prohibiting the input from the one input means 30 to the control means 11 is provided, it is possible to prevent erroneous input due to the unstable power supply voltage due to the low AC voltage of the commercial power supply 5. Can do.

(Embodiment 3)
FIG. 5 shows a block diagram of a rice cooker according to Embodiment 3 of the present invention.

  As shown in FIG. 5, the third stop means 40 is configured to stop induction heating for a fixed time after the detection voltage detected by the voltage detection means 21 becomes a constant voltage. Other configurations are the same as those of the first embodiment, and the same reference numerals are given and description thereof is omitted.

  The operation in the above configuration will be described. In the third stop means 40, the voltage of the commercial power supply 5 detected by the voltage detection means 21 becomes an AC voltage necessary for the power supply circuit 20 to make a voltage that can reliably drive the inverter circuit 9 of the drive means 10. After that, by prohibiting induction heating for a certain period of time, it is possible to eliminate the influence of power fluctuation due to noise or the like, and accompanying a transient voltage change of the power supply circuit 20 due to a power failure or a sudden voltage drop. It is possible to prevent circuit malfunctions and overloads applied to circuit elements.

  As described above, in the present embodiment, since the third stop unit 40 that stops induction heating for a certain period of time after the detection voltage detected by the voltage detection unit 21 becomes a constant voltage, the commercial power source is provided. Even if the AC voltage of 5 becomes a certain constant voltage, by prohibiting induction heating for a certain period of time until the level stabilizes, induction heating can be prohibited while the voltage is unstable, and the circuit operates correctly. The overload can be prevented from being applied to the circuit element.

(Embodiment 4)
FIG. 6 shows a block diagram of a rice cooker according to Embodiment 4 of the present invention.

  As shown in FIG. 6, the fourth stopping unit 50 prohibits input from the first input unit 30 to the control unit 11 for a certain period of time after the detection voltage detected by the voltage detection unit 21 becomes a constant voltage. I am doing so. Other configurations are the same as those of the second embodiment, and the same reference numerals are given and description thereof is omitted.

  The operation in the above configuration will be described. The fourth stop means 50 is configured such that the voltage of the commercial power supply 5 detected by the voltage detection means 21 is changed to an AC voltage necessary for the power supply circuit 20 to generate a voltage that allows the first input means 30 to operate reliably. Then, by prohibiting input for a certain period of time, it is possible to eliminate the influence of power fluctuation due to noise and the like, and to reduce the output voltage drop of the power supply circuit 20 due to a transient voltage change such as a power failure or voltage drop. The accompanying erroneous input can be prevented.

  As described above, in the present embodiment, the fourth input unit that prohibits input from the first input unit 30 to the control unit 11 for a certain period of time after the detection voltage detected by the voltage detection unit 21 becomes a constant voltage. Since the stop means 50 is provided, even if the AC voltage of the commercial power supply 5 becomes a certain voltage, the voltage is unstable by prohibiting the input from the first input means 30 for a certain time until the level is stabilized. It is possible to prohibit input during a period, and to prevent erroneous input.

(Embodiment 5)
FIG. 7 shows a block diagram of a rice cooker according to Embodiment 5 of the present invention.

  As shown in FIG. 7, the calculation means 60 performs a calculation based on the output of the first input means 30 and the output from the voltage detection means 21 and outputs the result. The second input unit 61 performs input correction based on the output from the calculation unit 60. Other configurations are the same as those of the second embodiment, and the same reference numerals are given and description thereof is omitted.

  The operation in the above configuration will be described. The calculation means 60 performs calculation using two values, that is, the output from the voltage detection means 21 and the output from the first input means 30. As a result, the second input means 61 becomes an AC voltage necessary for the power supply circuit 20 to produce a voltage that allows the first input means 30 to operate reliably, and the output value of the first input means 30 is A normal value is output to the control means 11 only when the value is normal, and an abnormal value is output otherwise, resulting in an output voltage drop of the power supply circuit 20 due to a transient voltage change such as a power failure or a voltage drop. Incorrect input can be prevented.

  The calculation means 60 can be realized not only by a calculation by a microcomputer but also by a logical calculation by a logic element.

  As described above, in the present embodiment, the calculation means 60 that performs calculation based on the output of the first input means 30 and the output from the voltage detection means 21 and outputs the result, Since the second input unit 61 that performs input correction by output is provided, the input from the second input unit 61 based on the output from the calculation unit 60 enables stable input regardless of the power supply voltage. Can be obtained.

(Embodiment 6)
FIG. 8 shows a block diagram of a rice cooker according to Embodiment 6 of the present invention.

  As shown in FIG. 8, the calculation means 60 performs a calculation based on the output from the first input means 30 and the output from the voltage detection means 21 and outputs the result. The fifth stopping means 70 stops the induction heating by the output of the calculating means 60. Other configurations are the same as those of the first embodiment, and the same reference numerals are given and description thereof is omitted.

  The operation in the above configuration will be described. The calculation means 60 performs calculation using two values, that is, the output from the voltage detection means 21 and the output from the first input means 30. As a result, the fifth stopping means 70 becomes an AC voltage necessary for the power supply circuit 20 to produce a voltage that can reliably drive the inverter circuit 9 of the driving means 10, and the output value of the first input means 30 is A normal value is output to the control means 11 only when it is a normal value, and an abnormal value is output otherwise, resulting in a drop in the output voltage of the power supply circuit 20 due to a transient voltage change such as a power failure or a voltage drop. It is possible to prevent circuit malfunctions and overloads applied to circuit elements.

  As described above, in the present embodiment, induction heating is stopped by the output of the calculation means 60 that performs a calculation based on the output of the first input means 30 and the output of the voltage detection means 21 and outputs the result. Since the fifth stopping means 70 is provided, induction heating can be performed in a state where the power supply voltage is stable.

  As described above, the rice cooker according to the present invention correctly operates even during a power failure or a sudden voltage drop, and can prevent a load from being applied to circuit elements. It is useful as a rice cooker having a DC power supply.

The block diagram of the rice cooker of Embodiment 1 of this invention Cross section of the rice cooker Partial block diagram of the rice cooker The block diagram of the rice cooker of Embodiment 2 of this invention The block diagram of the rice cooker of Embodiment 3 of this invention Block diagram of rice cooker according to Embodiment 4 of the present invention The block diagram of the rice cooker of Embodiment 5 of this invention Block diagram of rice cooker according to Embodiment 6 of the present invention Block diagram of a conventional rice cooker

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inner pan 2 Rice cooker main body 3 Heating coil 4 Unidirectional power supply 5 Commercial power supply 6 Smoothing circuit 7 Resonance capacitor 8 Switching element 9 Inverter circuit 10 Driving means 11 Control means 20 Power supply circuit 21 Voltage detection means 22 First stop means

Claims (6)

A rice cooker body having an open top surface, an inner pot detachably housed in the rice cooker body, a heating coil for induction heating the inner pot, a unidirectional power source obtained by rectifying commercial power, and switching An inverter circuit having an element, a resonance capacitor, and a smoothing circuit, which converts the unidirectional power source into high-frequency power, driving means for driving the switching element, and induction at the time of rice cooking or warming by controlling the driving means Control means for controlling heating, power supply circuit for supplying an operating current to each part of the circuit, voltage detection means for detecting the voltage of the commercial power supply, and induction heating when the detection voltage detected by the voltage detection means is below a certain voltage The rice cooker provided with the 1st stop means to stop. First input means that performs normal operation only when supplied from the power supply circuit, and instead of the first stop means, when the detection voltage detected by the voltage detection means is below a certain voltage, the first input means The rice cooker of Claim 1 provided with the 2nd stop means which prohibits the input to the said control means. The rice cooker according to claim 1, further comprising third stop means for stopping induction heating for a predetermined time after the detection voltage detected by the voltage detection means becomes a constant voltage, instead of the first stop means. Instead of the second stop means, a fourth stop means for prohibiting input from the first input means to the control means for a predetermined time after the detection voltage detected by the voltage detection means becomes a constant voltage. Item 2. A rice cooker according to item 2. Instead of the second stopping means, an arithmetic means for performing an operation based on the output of the first input means and the output from the voltage detecting means and outputting the result, and an input correction is performed by the output from the arithmetic means. The rice cooker of Claim 2 provided with the 2nd input means. A first input unit that performs normal operation only when supplied from a power supply circuit; and an arithmetic unit that performs an operation based on an output of the first input unit and an output from the voltage detection unit and outputs a result. And it replaced with the 1st stop means, The rice cooker of Claim 1 provided with the 5th stop means which stops induction heating by the output of the said calculating means.

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