JP4114547B2 - Induction heating cooker - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to an induction heating cooker used in general homes and the like. More specifically, the present invention includes a plurality of induction heating coils, and one induction heating coil surrounds the other induction heating coil. It is related with the induction heating cooking appliance characterized by the structure which was able to connect between the terminals of the coil for induction heating installed in the outer side.
[0002]
[Prior art]
  Conventionally, as a configuration of an induction heating cooker having a plurality of induction heating coils and selecting or switching a coil to be induction heated, for example, a high frequency injected into a plurality of induction heating coils as shown in FIG. There is a configuration in which the presence or absence of current is controlled by the operation of an inverter circuit (see, for example, Patent Document 1).
[0003]
  In FIG. 3, 1 is a commercial power source, 2 is a frequency conversion means, and is composed of 3 rectifier circuits and 4 inverter circuits. Reference numeral 5 denotes a control means including 5a operation means, 5b display means, and 5c notification means, and further controls the induction heating by outputting a control signal to the inverter circuit 4a and the inverter circuit 4b. Reference numeral 6 denotes a first coil, and reference numeral 7 denotes a second coil, which is supplied with high-frequency current from the inverter circuits 4a and 4b in accordance with a control signal from the control means 5, and is not particularly shown in the figure. An object to be heated such as a pan placed on the coil 6 or the second coil 7 is heated.
[0004]
  The first coil 6 includes a first inner terminal 6a and a first outer terminal 6b, and the second coil 7 includes a second inner terminal 7a and a second outer terminal 7b, and the first coil 6 and the second coil 7 are not connected to each other and are independently connected to corresponding inverter circuits.
[0005]
  The operation | movement is demonstrated about the conventional induction heating cooking appliance comprised as mentioned above.
[0006]
  When the user inputs a heating command to the operation unit 5a, the control unit 5 informs the user that the command is received by the display unit 5b and the notification unit 5c, and the heating command corresponding to the received command is the first. It outputs to the inverter circuit 4a and the second inverter circuit 4b.
[0007]
  The first inverter circuit 4 a and the second inverter circuit 4 b supply high-frequency currents to the first coil 6 and the second coil 7, respectively, in accordance with a heating command from the control means 5. Therefore, although not specifically described in the figure, an object to be heated such as a pan placed on the first coil 6 and the second coil 7 is heated.
[0008]
  Thus, in the heating control means of the induction heating cooker shown in FIG. 3, the induction heating coil supplies high frequency current to each induction heating coil from the inverter circuit as necessary, and if there is no need to heat, the induction heating coil In general, the control is performed without supplying a high-frequency current.
[0009]
  However, in an induction heating cooker installed so that one induction heating coil surrounds the other induction heating coil, if the diameter of the bottom surface of the pan is small or the pan is removed from a predetermined position When placed, even if the coil placed outside is not heating, the high frequency magnetic field emitted from the inside coil is not fully absorbed by the pan and radiated to the outside, causing malfunction of other electrical products A defect may occur.
[0010]
  Therefore, as a general means for suppressing the high-frequency magnetic field radiated to the outside without being sufficiently absorbed by the pan, a means for reducing the radiated magnetic flux by installing a conductive ring on the outer periphery of the induction heating coil Is used (see, for example, Patent Document 2).
[0011]
  As a result, there is a need for a space for installing a conductive ring on the outer periphery, and the inner coil and the outer ring have a distance. A new conductive ring is required.
[0012]
[Patent Document 1]
    JP-A-5-347180
[Patent Document 2]
    Japanese Patent Laid-Open No. 7-22170
[0013]
[Problems to be solved by the invention]
  However, in the conventional configuration, the high frequency current is supplied from the first inverter circuit to the first coil and the high frequency current is supplied from the second inverter circuit to the second coil. When the bottom area of the pan is small, or when the pan is placed at a place deviated from the predetermined position, even if the second coil disposed on the outer periphery does not perform the heating operation, The generated high frequency magnetic field is not sufficiently absorbed by the pan and is radiated to the outside, which may cause a malfunction such as malfunction of other electrical products.
[0014]
  In order to suppress the magnetic field leaking from the first coil that performs the induction heating to the surroundings, a new magnetic shielding means such as a conductive ring is required on the outer periphery of the induction heating coil. Had.
[0015]
  In view of the above, the present invention solves the above-described conventional problems, and a second coil for induction heating is installed on the outer periphery of the first coil for induction heating, and the terminal of the second coil is provided. When the first coil performs induction heating without causing the second coil to perform a heating operation, the terminals of the second coil can be short-circuited to form the first coil. An object of the present invention is to provide an induction heating cooker capable of suppressing a magnetic field leaking to the surroundings without being absorbed by a pan in a generated high-frequency magnetic field.
[0016]
[Means for Solving the Problems]
  In order to solve the conventional problem, an induction heating cooker according to the present invention includes a first coil for induction-heating an object to be heated, and an outer side of the first coil.TheA second coil arranged to surround and inductively heat an object to be heated; a first switch capable of opening and closing a connection between one terminal of the second coil and another terminal; and the first coil Alternatively, an inverter circuit that supplies a high-frequency current to one or both of the second coils, and a control unit that controls the operation of the first switch and the inverter circuit, the control unit includes: When high frequency current is not supplied to the second coilAnd only when the first coil is heated more than a predetermined heating powerThe terminal of the second coil is short-circuited by the first switch, and the magnetic flux radiated from the first coil to the outside of the device is reduced.
[0017]
  Accordingly, when the first coil performs induction heating without performing the heating operation by the second coil, the high frequency radiated from the first coil is obtained by connecting the terminals of the second coil. An induction heating cooker is obtained that makes it possible to reduce the magnetic field leaking to the surroundings without being absorbed by the pan in the magnetic field.
[0018]
In addition, the opportunity for driving the first switch is reduced, and the contact is opened and closed only when the magnetic flux leaking to the outside needs to be reduced, so that the contact of the first switch is prevented from deteriorating. In addition, power consumption for driving the switch can be reduced.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
  The invention according to claim 1 is a first coil for inductively heating an object to be heated, and an outer side of the first coil.TheA second coil arranged to surround and inductively heat an object to be heated; a first switch capable of opening and closing a connection between one terminal of the second coil and another terminal; and the first coil Alternatively, an inverter circuit that supplies a high-frequency current to one or both of the second coils, and a control unit that controls the operation of the first switch and the inverter circuit, the control unit includes: When high frequency current is not supplied to the second coilAnd only when the first coil is heated more than a predetermined heating powerThe terminal of the second coil that performs induction heating is to reduce the magnetic flux radiated from the first coil to the outside of the device by short-circuiting the terminals of the second coil by the first switch. By providing the structure which short-circuits between, the induction heating cooking appliance which makes it possible to suppress the magnetic field which is not absorbed by the pan but leaks to the periphery in the high frequency magnetic field emitted from the first coil can be provided.
[0020]
  AlsoIn addition to reducing the opportunity to drive the first switch and opening and closing the contact only when it is necessary to reduce the magnetic flux leaking to the outside, the contact of the first switch is prevented from deteriorating, In addition, power consumption for driving the switch can be reduced.
[0021]
  Claim2According to the invention described above, in the above configuration, particularly when the high frequency current is not supplied to the first coil, the contact of the first switch is opened and closed, so that a spark is generated when the contact is opened and closed. The magnetic flux radiated to the outside can be reduced while suppressing deterioration of the contacts and preventing deterioration of the contacts.
[0022]
  Claim3The described inventionA first coil for inductively heating the object to be heated; a second coil for inductively heating the object to be heated, which is disposed to surround the first coil; one terminal of the second coil, and the like A first switch capable of opening and closing a connection with the terminal of the first coil, and the first coil Alternatively, an inverter circuit that supplies a high-frequency current to one or both of the second coils, the first switch, and a second switch that interrupts electrical connection between the first coil and the second coil. And control means for controlling operations of the first switch, the second switch, and the inverter circuit;WithThe control means short-circuits between the terminals of the second coil by the first switch when the inverter circuit supplies a high-frequency current to the first coil and does not supply the second coil to the second coil. In caseFirst2Coil and the first1It is possible to cut off the electrical connection with the coil of the coil, prevent the potential of the second coil from fluctuating, and reduce the electric field radiated to the outside of the device.Induction heating cooker can be provided.
[0023]
【Example】
  Example 1
  An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a circuit configuration of an induction heating cooker according to a first embodiment of the present invention.
[0024]
  In FIG. 1, 1 is a commercial power source, 2 is a frequency conversion means, which is composed of 3 rectifier circuits and 4 inverter circuits. Reference numeral 5 denotes a control means including 5a operation means, 5b display means, and 5c notification means, and further outputs a control signal to the inverter circuit 4 to control induction heating. Reference numeral 6 denotes a first coil, and reference numeral 7 denotes a second coil, which is supplied with a high-frequency current from the inverter circuit 4 in accordance with a control signal from the control means 5, and is not particularly shown in the figure. Alternatively, an object to be heated such as a pan placed on the second coil 7 is heated.
[0025]
  The first coil 6 includes a first inner terminal 6a and a first outer terminal 6b, and the second coil 7 includes a second inner terminal 7a, a second outer terminal 7b, and a second intermediate terminal 7c. In the present embodiment, the first inner terminal 6 a and the first outer terminal 6 b are always connected to the inverter circuit 4.
[0026]
  8 is a first switch, whether the second outer terminal 7b is connected to the output terminal of the inverter circuit 4, or is connected to the second inner terminal 7a to short-circuit all the second coils, Alternatively, it is possible to switch whether a part of the second coil is short-circuited by being connected to the second intermediate terminal 7c, and in this embodiment, it is connected to the output terminal of the inverter circuit 4 in a normal state where there is no specific instruction. Yes.
[0027]
  Reference numeral 9 denotes a second switch, and the second inner terminal 7a is electrically connected to the first outer terminal 6b which is a terminal of the first coil 6, or is electrically connected to the first coil 6. It is possible to switch between being connected to earth by cutting off the connection. In the present embodiment, the second switch 9 in a normal state where there is no specific instruction connects the second inner terminal 7a and the output terminal of the inverter circuit 4 connected to the first outer terminal 6b. is doing.
[0028]
  Reference numeral 10 denotes an input current detection means, which in this embodiment detects a current input to the frequency conversion means 2 by a current transformer and outputs a detection result to the inverter circuit 4.
[0029]
  Reference numeral 11 denotes second coil current detection means, which detects the current flowing through the second coil 7 by a current transformer in this embodiment, and outputs the detection result to the inverter circuit 4.
[0030]
  The operation | movement is demonstrated about the induction heating cooking appliance comprised as mentioned above.
[0031]
  When the user inputs a heating command to the operation means 5a, the control means 5 informs the user that the command has been received by the display means 5b and the notification means 5c, and the heating command corresponding to the received command is transmitted to the inverter circuit 4. To output.
[0032]
  The inverter circuit 4 drives the first switch 8 and the second switch 9 in accordance with the heating command from the control means 5, and to one or both of the first coil 6 and the second coil 7. Supply high-frequency current. Therefore, although not specifically described in the figure, an object to be heated such as a pan placed on the first coil 6 and the second coil 7 is heated.
[0033]
  If the induction heating operation by the second coil 7 is not performed as a heating command from the control means 5, the first switch 8 is driven to connect the second inner terminal 7a or the second intermediate terminal 7c and the second Two outer terminals 7b are short-circuited. Thus, when a high frequency current is supplied to the first coil 6, a high frequency current is induced in the second coil 7 due to the magnetic field generated by the first coil 6. The magnetic field generated by the high-frequency current induced in the second coil 7 intensifies the magnetic field generated by the first coil 6 inside the second coil 7 and the first coil outside the second coil 7. 6, the magnetic field leaking outward from the first coil 6 is reduced.
[0034]
  Further, when the first coil 6 performs a heating operation of a predetermined heating power or more, the terminals of the second coil 7 are short-circuited by the first switch 8 by short-circuiting the terminals of the second coil 7. By reducing the opportunity to drive the first switch 8 that is short-circuited and driving the first switch 8 only when it is necessary to reduce the magnetic flux that leaks to the outside, the contacts inside the first switch 8 And the consumption of electric power for driving the first switch 8 is reduced.
[0035]
  Further, when a predetermined high-frequency current is supplied while the amount of current supplied to the second coil 7 is detected by the second coil current detection means 11, the frequency conversion means 2 detected by the input current detection means 10. If the input current amount to is small, the inverter circuit 4 determines that the magnetic flux generated from the second coil 7 is not sufficiently absorbed in the pan as the article to be heated 22 and leaks to the outside. The inverter circuit 4 stops the supply of high-frequency current to the second coil 7 to stop the generation of magnetic flux, and short-circuits the terminals of the second coil 7 so as to perform induction heating from the first coil 6. The radiated magnetic flux is prevented from leaking outside the device without being absorbed by the object to be heated 22.
[0036]
  Further, when the terminals of the second coil 7 are short-circuited by the output signals from the various detection means, the display means 5b and / or the notification means 5c are used by the second coil 7 to the user. By notifying that the heating operation is stopped and the shield operation is performed, the user understands that cooking on the second coil 7 cannot be performed, and can perform cooking corresponding to the situation. I can do it.
[0037]
  Further, when an operation such as short-circuiting or releasing a contact in the first switch 8 is performed by an output signal of various detection means or a setting input by the user to the control means 5, the first coil 6 is controlled on the condition that no high-frequency current is supplied to 6, the discharge between the electrodes that may occur when short-circuiting or releasing is suppressed, and deterioration of the first switch 8 is prevented.
[0038]
  Further, when a high-frequency current is supplied to the first coil 6 by short-circuiting the terminals of the second coil 7, the first coil 6 is not absorbed by the heating load but is released to the outside of the device. A high-frequency current is induced in the second coil 7 in accordance with the amount of magnetic flux to be generated. Therefore, the second coil current detection means 11 detects the amount of magnetic flux emitted from the first coil 6 to the outside while detecting the high-frequency current induced in the second coil 7, and the first coil 6. By controlling the amount of high-frequency current supplied to 6, the amount of magnetic flux leaking is suppressed to a predetermined value or less.
[0039]
  Further, when a high frequency current induced by the first coil 6 is caused to flow by short-circuiting the terminals of the second coil 7, it is electrically connected to the first outer terminal 6 b that is a terminal of the first coil 6. By switching the connected second switch 9 and grounding the second inner terminal 7a, which is the terminal of the second coil 7, the potential of the second coil 7 does not fluctuate and the emission of the electric field is suppressed. The
[0040]
  The second coil 7 has three terminals such as a second inner terminal 7 a, a second outer terminal 7 b, and a second intermediate terminal 7 c, and a high frequency current supplied to the first coil 6. When the amount of input current detected by the input current detection means 10 is small with respect to the amount of current, it is determined that the amount of magnetic flux radiated to the outside of the device is large, and the second inner terminal 7a and the second outer side Terminal 7bAnd short circuit. When it is determined that the amount of magnetic flux is small, the second intermediate terminal 7c and the second outer terminal 7bBy selecting and short-circuiting, the amount of magnetic flux leaking to the outside of the device is controlled and reduced.
[0041]
  As described above, according to the present embodiment, when the high frequency current is not supplied to the second coil 7, the terminals of the second coil 7 are short-circuited to leak outward from the first coil 6. The magnetic field to be reduced can be reduced.
[0042]
  In addition, when the first coil 6 performs a heating operation of a predetermined heating power or more, the contacts inside the switch when operating the first switch 8 are short-circuited between the terminals of the second coil 7. It is possible to reduce the consumption of electric power for driving the switch and to reduce the magnetic field leaking outward from the first coil 6 while preventing the deterioration.
[0043]
  Further, the second coil current detection means 11 and the input current detection means 10 detect that the amount of magnetic flux leaking to the outside is large, and the terminals of the second coil 7 are short-circuited so that the magnetic flux can be obtained as necessary. Can be prevented from being emitted to the outside of the device.
[0044]
  In addition, when the terminals of the second coil 7 are short-circuited, the display means 5b and the notification means 5c are provided with a configuration that informs the user that the terminals of the second coil 7 are short-circuited. Thus, the user can understand that the leakage of magnetic flux is suppressed and cooking cannot be performed on the second coil 7.
[0045]
  The operation of opening and closing the contacts in the first switch 8 is performed when high-frequency current is not supplied to the first coil 6, thereby suppressing the discharge between the contacts. 8 deterioration can be prevented.
[0046]
  Further, by short-circuiting the terminals of the second coil 7 and detecting the amount of the high-frequency current induced by the high-frequency magnetic field output from the first coil 6, the load of the output of the first coil 6 is applied. By detecting the amount of magnetic flux leaking without being absorbed and adjusting the amount of high-frequency current input to the first coil 6, the amount of magnetic flux leaking can be suppressed to a predetermined value or less.
[0047]
  Moreover, while short-circuiting between the terminals of the second coil 7 to suppress leakage of the magnetic flux generated by the first coil 6 to the outside, the second coil 7 is electrically separated from the first coil 6, Further, by connecting to a stable potential, the emission of an electric field to the outside can be suppressed.
[0048]
  The second coil 7 has three terminals such as a second inner terminal 7a, a second outer terminal 7b, and a second intermediate terminal 7c, depending on the amount of magnetic flux radiated to the outside of the device. By selecting and short-circuiting the terminals, the amount of magnetic flux leaking to the outside of the device is controlled and reduced.
[0049]
  (referenceExample1)
  One aspect of the present inventionreferenceExamples will be described with reference to the drawings. FIG. 2 shows the first aspect of the present invention.oneofreferenceThe structure of the induction heating cooking appliance in an example is shown.
[0050]
  In FIG. 2, 6 is the first coil shown in FIG. 1 of the first embodiment, and 7 is the second coil shown in FIG. 1 of the first embodiment. The first coil 6 and the second coil 7 are arranged, and a pan or the like as a heated object 22 is placed on the upper surface of the top plate 21.
[0051]
  Reference numeral 23 denotes a pan installation detecting means, which is installed in the vicinity of the second coil 7 and detects whether or not a load such as a dedicated pan that is a target to be heated by the second coil 7 is placed. Concretely bookreferenceIn the example, the presence / absence of a pan as the object to be heated 22 is detected by a sliding switch having a built-in magnet.
[0052]
  Reference numeral 24 denotes pan deviation detecting means for determining the ratio of the metal to be heated to the projected area of the second coil 7. Concretely bookreferenceIn the example, a conductor is disposed on a portion corresponding to the projected area of the second coil 7 on the lower surface of the top plate 21, and the ratio of the pot due to the coupling of the conductor and the object 22 to be heated by the capacitance. And the ratio of whether the heated object 22 is placed in the correct position on the pan deviation detecting means 24 or the percentage of the pan deviation detecting means 24 covered if the position is misaligned is detected. is doing.
[0053]
  Also,referenceExample1In this case, the pan displacement detecting means 24 arranges a conductor on the lower surface of the top plate 21 and detects the signal from the coupling of the conductor and the object to be heated 22 by the electrostatic capacity. Can be used, it is also possible to determine how much the position of the object to be heated 22 is shifted by providing a plurality of light receiving elements.referenceAn example is that the second coil 7 is detected after detecting that the object to be heated 22 is displaced from a predetermined position or has a bottom area smaller than a predetermined area, regardless of the configuration and accuracy of the pan displacement detecting means 24. The effect is achieved by short-circuiting the terminals.
[0054]
  The operation | movement is demonstrated about the induction heating cooking appliance comprised as mentioned above.
[0055]
  When a pan, which is a heated object 22 made of a magnetic material and having a bottom surface larger than the outer shape of the second coil, is placed on the top plate 21 of the induction heating cooker, the pan installation detection circuit 23 incorporating the magnet has a magnet. By adsorbing to the pot, the presence of the pot is detected and a heating signal is output to the inverter circuit 4.
[0056]
  When the pan as the object to be heated 22 is lifted or when the pan is shifted to the left side in FIG. 2, it is immediately detected that there is no pan immediately above the pan installation detection means 23, and the second Since the terminals of the coil 7 are short-circuited, the magnetic field radiated from the first coil 6 and the second coil 7 can be prevented from leaking to the outside. Furthermore, when the heating by the second coil 7 is inappropriate on the top plate 21, for example, when a heated object 22 having a small bottom diameter is placed, the pot setting detection means 23 sets an appropriate pot. In order to detect that this is not done and to output a heating stop signal to the inverter circuit 4, the terminals of the second coil 7 are short-circuited to prevent leakage of magnetic flux.
[0057]
  Further, when a pan, which is a heated object 22 made of a non-magnetic material and having a bottom surface larger than the outer shape of the second coil, is placed on the top plate 21 of the induction heating cooker, a pan installation detection means 23 incorporating a magnet is provided. Erroneously detects that the pan does not exist because the magnet does not stick to the pan, and outputs a heating stop signal to the inverter circuit 4, but the pan misalignment detection means 24 has a large capacitance so that the pan is in the correct position. Since it detects that it is placed and outputs a heating signal to the inverter circuit 4, the heating operation by the second coil 7 becomes possible.
[0058]
  In addition, when the pan is slightly lifted or when the pan is slightly shifted, if the heating power is low, the amount of magnetic flux that leaks is small. Therefore, it is not always necessary to stop the heating by the second coil 7. Therefore, when the ratio of the metal to be heated on the projected area of the second coil 7 decreases and the amount of magnetic flux leaking increases, a heating stop signal is sent from the pan deviation detecting means 24 to the inverter circuit 4. Is output, the heating operation by the second coil 7 is stopped, the terminals of the second coil 7 are short-circuited to form a shield wire, and the leakage magnetic flux is suppressed.
[0059]
  Book as abovereferenceAccording to the example, in the configuration in which the terminals of the second coil 7 are short-circuited, a load such as a dedicated pan that is a target to be heated by the second coil 7 is not placed by providing the pan installation detection means 23. In this case, a heating stop signal is output from the pan setting detection means 23, and the inverter circuit 4 does not supply a high-frequency current to the second coil 7, but connects between the terminals of the second coil 7, It is possible to reduce leakage of magnetic flux radiated from one coil 6 to the outside.
[0060]
  Further, by providing the pan displacement detecting means 24, when a metal pan is placed at a position deviated from the projected area of the second coil 7, a heating stop signal is output from the pan displacement detecting means 24. The inverter circuit 4 connects the terminals of the second coil 7 without supplying high-frequency current to the second coil 7, and the magnetic flux radiated from the first coil 6 leaks to the outside. Can be reduced.
[0061]
  In the first embodiment, one first coil 6 exists inside the second coil 7, but there are a plurality of first coils 6 inside the second coil 7. Even in this case, by short-circuiting the terminals of the second coil, the effect of the present invention that prevents the magnetic flux radiated from the first coil 6 from leaking to the outside of the device can be achieved.
[0062]
  Further, in the first embodiment, the second coil 7 is outside the first coil 6.TheAlthough one piece is disposed so as to surround the first coil 6, even if there are a plurality of second coils 7 outside the first coil 6, the first coil 6 can be short-circuited between the terminals of the second coil. The effect of this invention which prevents that the magnetic flux radiated | emitted from the outside leaks out of an apparatus can be show | played.
[0063]
  In the first embodiment, the second switch 9 is connected to the second inner terminal 7a, the first coil 6, or the ground, but is not connected to the ground. In both cases, the electrical connection with the first coil 6 is cut off, whereby the potential of the second coil 7 can be prevented from fluctuating and the effect of the present invention can be achieved, which reduces the leakage of the electric field.
[0064]
  In the first embodiment, the inverter circuit 4 drives the first switch 8 and the second switch 9, but the first switch 8 and the second switch 9 are driven by the inverter. The control means 5 is not limited to the circuit 4 and may be performed by short-circuiting the terminals of the second coil 7 and connecting the second coil 7 short-circuited between the terminals to a fixed potential. The effects of the invention can be achieved.
[0065]
  In the first embodiment, when the terminal of the second coil 7 to be short-circuited is selected, the amount of the high-frequency current supplied to the first coil 6 and the input current detected by the input current detecting means 11 are selected. The amount of magnetic flux leaking was determined based on the correlation with the amount. Regardless of the means for detecting the amount of magnetic flux, the entire second coil 7 is short-circuited when the amount of magnetic flux is large, and the second when the amount of magnetic flux is small. The effect of the present invention can be achieved by corresponding to the amount of short-circuiting according to the amount of magnetic flux, such as short-circuiting part of the second coil.
[0066]
  Also,referenceExample1The pan setting detection means 23 uses a sliding switch with a built-in magnet, but a material that can be inductively heated with a built-in switch that detects engagement with the object to be heated 22 and a coil that generates magnetic flux. Any detector that detects whether or not a load to be induction-heated is placed on the second coil 7, such as a detection unit that detectsreferenceAlthough only one is provided in the example, it goes without saying that the detection accuracy is higher when there are a plurality of them.
[0067]
  Also,referenceExample1In this case, the pan displacement detecting means 24 arranges a conductor on the lower surface of the top plate 21 and detects the signal from the coupling of the conductor and the object to be heated 22 by the electrostatic capacity. Can be used, it is also possible to determine how much the position of the object to be heated 22 is shifted by providing a plurality of light receiving elements.referenceFor example, regardless of the configuration and accuracy of the pan displacement detecting means 24, the second coil is detected when the heated object 22 is displaced from a predetermined position or when the bottom area is smaller than the predetermined area. The effect is achieved by short-circuiting the terminals 7.
[0068]
【The invention's effect】
  As described above, claims 1 to3According to the invention, the magnetic field leaking to the surroundings without being absorbed by the pan in the high-frequency magnetic field emitted from the first coil is provided by providing a configuration for short-circuiting the terminals of the coil of the brother 2 that performs induction heating. An induction heating cooker that can be suppressed can be provided.
[0069]
In addition, the opportunity for driving the first switch is reduced, and the contact is opened and closed only when the magnetic flux leaking to the outside needs to be reduced, so that the contact of the first switch is prevented from deteriorating. In addition, power consumption for driving the switch can be reduced.
[Brief description of the drawings]
FIG. 1 is a diagram showing a circuit configuration of an induction heating cooker in Embodiment 1 of the present invention.
FIG. 2 of the present inventionreferenceExample1Showing the configuration of the induction heating cooker
FIG. 3 is a diagram showing a circuit configuration of a conventional induction heating cooker
[Explanation of symbols]
  1 Commercial power supply
  2 Frequency conversion means
  3 Rectifier circuit
  4 Inverter circuit
  5 Control means
  6 First coil
  7 Second coil
  8 First switch
9 Second switch

Claims (3)

A first coil for inductively heating the object to be heated; a second coil for inductively heating the object to be heated that surrounds the outside of the first coil; one terminal of the second coil; A first switch capable of opening and closing the connection to the terminal, an inverter circuit for supplying a high-frequency current to one or both of the first coil and the second coil, the first switch, and the inverter circuit Control means for controlling the operation of the control circuit, the control means only when the inverter circuit does not supply a high frequency current to the second coil and when the first coil performs a heating operation of a predetermined heating power or more. An induction heating cooker that reduces the magnetic flux radiated from the first coil to the outside of the device by short-circuiting the terminals of the second coil by the first switch. Control means, induction heating cooker according to claim 1 high-frequency current to the first coil at a timing which is not being supplied, for opening and closing the contacts of the first switch. A first coil for inductively heating the object to be heated; a second coil for inductively heating the object to be heated, which is disposed to surround the first coil; one terminal of the second coil, and the like A first switch capable of opening and closing the connection to the terminal, an inverter circuit for supplying a high-frequency current to one or both of the first coil and the second coil, the first switch, comprising a coil and a second switch for interrupting the electrical connection between the second coil, and control means for controlling the operation of said first switch and the second switch and the inverter circuit, the control When the inverter circuit supplies a high frequency current to the first coil and does not supply the second coil to the second coil, the first switch shorts between the terminals of the second coil. , the second Induction cooker it cuts off the electrical connection between the coil and the first coil.

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