JP2011090914A - Inductive heating apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inductive heating apparatus which surely detects boil-over and of which cleaning of a top plate is easy. <P>SOLUTION: The inductive heating apparatus has: the top plate 2 to mount a cooking container 1; a heating coil 3 which generates an inductive magnetic field in order to heat the cooking container 1; a heating control section 4 which controls high frequency current supplied to the heating coil 3 and controls heating electric power of the cooking container 1; a plurality of electrodes 5 of the same area arranged on the lower face of the top plate 2; and a capacitance detector 6 to detect changes in capacitance caused in the electrodes 5 by the fact that a cooked object is adhered to the top plate 2. When the changes in capacitance are detected by the capacitance detector 6, the heating power is controlled to be changed by the heating control section 4. By nearly equalizing a wiring length to connect the electrodes 5 and the capacitance detector 6, detection variations in boil-over of respective electrodes can be suppressed. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an induction heating device used in general homes, restaurants, offices, and the like.

  Conventionally, this type of induction heating device changes the capacitance by covering the electrode placed on the lower surface of the top plate with a cooking container or food spilled from the cooking container. A detection method is disclosed (for example, see Patent Document 1).

JP 2008-159494 A

  However, the conventional configuration has a problem that the influence of the electric field generated during induction heating differs depending on the size and placement position of the cooking container, the shape and arrangement of the electrodes, and the like.

  The present invention solves the above-described conventional problems, and provides an induction heating device that can easily detect spillage by using the same method of receiving the influence of the electric field even if the size of the cooking container or the electrode changes. With the goal.

  In order to solve the above-described conventional problems, an induction heating apparatus according to the present invention includes a top plate on which a cooking container is placed, a heating coil that generates an induction magnetic field to heat the cooking container, and a high-frequency current supplied to the heating coil. A heating control unit for controlling the heating power of the cooking container, a plurality of electrodes of the same area arranged on the lower surface of the top plate, and a capacitance generated in the electrode by the object to be cooked adhering to the top plate And an induction heating device that controls the heating power to be changed by the heating control unit when the capacitance detecting unit detects that the capacitance has changed. Thus, the lengths of the wires connecting the electrodes and the capacitance detecting means are substantially equal.

  This makes adjustments such as changing the detection threshold of the detection circuit section for each electrode by making the influence of the electric field generated during induction heating substantially equal to the wiring connecting the electrode and the detection circuit section. It is possible to detect the spillage.

  According to the induction heating device of the present invention, detection can be reliably performed with the same detection sensitivity for each electrode, and adjustment of detection sensitivity can be made unnecessary.

The block diagram of the induction heating apparatus of Embodiment 1 of this invention. The figure which shows the electrostatic capacitance detection result of the electrostatic capacitance detection means of the induction heating apparatus in Embodiment 1 of this invention. Layout diagram when the wiring length connecting the electrode of the induction heating device and the capacitance detecting means in Embodiment 1 of the present invention is the same Layout diagram when the electrostatic capacity detection means of the induction heating apparatus in Embodiment 1 of the present invention is put together in one place The layout figure from which the wiring length which connects the electrode of the induction heating apparatus and electrostatic capacitance detection means in Embodiment 4 of this invention differs FIG. 10 is a diagram illustrating an example of detection of spillage in Embodiment 4 The figure which shows the layout of the metal part of the approximate vicinity of the electrode of the induction heating apparatus in Embodiment 6 of this invention The figure which showed the spilling on the metal part of the approximate vicinity of the electrode of the induction heating apparatus in Embodiment 6 of this invention

  1st invention controls the high frequency electric current supplied to the top plate which mounts a cooking vessel, the induction coil which generates an induction magnetic field in order to heat a cooking vessel, and the heating coil, and the heating electric power of a cooking vessel A heating control unit to be controlled, a plurality of electrodes having the same area disposed on the lower surface of the top plate, and a capacitance for detecting a change in capacitance generated in the electrode when an object to be cooked adheres to the top plate And an induction heating device that controls the heating power to be changed by the heating control unit when the capacitance detecting unit detects a change in capacitance. By making the wiring lengths connecting the capacitance detecting means substantially equal, the influence of the electric field generated during induction heating can be made substantially equal, and adjustment of detection sensitivity can be made unnecessary.

  In the second invention, in particular, the plurality of electrodes arranged on the lower surface of the top plate according to the first invention are formed by printing a conductive material on the top plate, so that the electrode and the top plate are integrated. Detection can be performed.

  In the third invention, in particular, the wiring connecting the electrode of the first invention and the capacitance detecting means can be configured by printing a conductive material on the top plate, thereby reducing the space inside the device. In addition, since fluctuations in capacitance can be suppressed, detection of spillage can be stabilized.

  4th invention controls the heating power of a cooking vessel by controlling the high frequency current supplied to the top plate which mounts a cooking vessel, the induction coil which generates an induction magnetic field in order to heat a cooking vessel, and the heating coil A heating control unit to be controlled, a plurality of electrodes having the same area disposed on the lower surface of the top plate, and a capacitance for detecting a change in capacitance generated in the electrode when an object to be cooked adheres to the top plate And an induction heating device that controls the heating power to be changed by the heating control unit when the capacitance detecting unit detects a change in capacitance. And the capacitance detecting means, the wiring length depends on the wiring length by setting the threshold value for detecting the change in capacitance according to the wiring length. By changing the threshold according to degree of influence of the electric field that can be the sensitivity of each electrode the same.

  5th invention controls the high frequency electric current supplied to the top plate which mounts a cooking container, the induction coil which generates an induction magnetic field in order to heat a cooking container, and the said heating coil, and the heating power of a cooking container A heating control unit for controlling, a plurality of electrodes disposed on the lower surface of the top plate, and a capacitance detecting means for detecting a change in capacitance generated in the electrodes due to the food to be cooked on the top plate; An induction heating device that controls the heating power to be changed by the heating control unit when the capacitance detecting means detects that the capacitance has changed. When the areas are different, the threshold value according to the degree of influence of the electric field depending on the electrode area is set by setting the threshold value for detecting the change in the capacitance according to the electrode area. Will be changed, the sensitivity of each electrode can be the same.

  6th invention controls the high frequency electric current supplied to the top plate which mounts a cooking vessel, the induction coil which generates an induction magnetic field in order to heat a cooking vessel, and the heating coil, and the heating power of a cooking vessel A heating control unit for controlling, a plurality of electrodes disposed on the lower surface of the top plate, and a capacitance detecting means for detecting a change in capacitance generated in the electrodes due to the food to be cooked on the top plate; An induction heating device that controls the heating power to be changed by the heating control unit when the capacitance detecting means detects that the capacitance has changed. By adopting a configuration in which the metal part is arranged in the vicinity, the capacitance detection means can be easily detected by allowing the heated object to spill over to both the electrode and the metal part. Can.

  In the seventh aspect of the invention, in particular, the metal part of the sixth aspect of the invention is detected by making the ratio of the spilled heated object to the metal part the same for each electrode by making the distance from the electrode substantially the same. Can be made the same accuracy.

  In the eighth aspect of the invention, in particular, the metal part of the sixth or seventh aspect of the invention is connected to the stable potential of the heating control part or the electrostatic capacity detection means, so that the detection of the electrostatic capacity detection means can be performed more reliably. can do.

  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 an induction heating apparatus in the first embodiment of the present invention.

  In FIG. 1, a top plate 2 on which a cooking container 1 for heating a cooked food is placed, a heating coil 3 for generating an induction magnetic field to heat the cooking container 1, and power from a commercial power source are converted. An inverter circuit 7 for supplying a high frequency current to the heating coil 3 and a heating control unit 4 for controlling the heating power of the cooking vessel 1 by controlling the inverter circuit 7 are configured.

  The electrode 5 is configured on the lower surface of the top plate 2, and a capacitance detecting means 6 for detecting a change in capacitance between the electrode 5 and another conductor is connected to the heating control unit 4, and heating is performed. The control unit 4 controls the inverter circuit 7 according to the result of the capacitance detection means 6 to change the high-frequency current supplied to the heating coil 3, thereby controlling the heating power to the cooking vessel 1.

  The cooking container 1 is a container in which to-be-cooked items such as ingredients are placed, and is a pan, a frying pan, a kettle or the like, and can be heated by induction heating.

  The cooking vessel 1 is placed on a top plate 2 that forms part of the outline of the induction heating device. At that time, the cooking container 1 is placed at a position facing the heating coil 3. The top plate 2 often uses crystallized glass, but is not limited thereto.

  The heating coil 3 is supplied with a high-frequency current from an inverter circuit 7 that operates according to an instruction from the heating control unit 4, and generates a high-frequency magnetic field by the current. An eddy current is generated in the cooking vessel 1 that has received the high-frequency magnetic field, and the cooking vessel 1 is heated by the eddy current.

  The heating control unit 4 is connected to an operation unit 8 and an inverter circuit 7 for a user of the induction heating device to instruct heating power and the like. For example, when the automatic cooking mode is instructed by the operation unit 8, the heating control unit 4 controls the inverter circuit 7 according to the content of the automatic cooking.

  In addition, even when the user starts or stops heating or adjusts the heating power from the operation unit 8, the heating control unit 4 controls the inverter circuit 7 so as to perform a desired operation. is there.

  The electrode 5 is a conductor formed on the lower surface of the top plate 2 by application or adhesion, and forms a capacitor with the conductor on the top plate 2. Normally, there is nothing on the top plate 2, so air plays its role.

  However, when another object such as the cooking container 1, fingers, water, or an object to be cooked is on the top plate 2, the capacitance changes because the relative permittivity of each object is different from that of air. This change in capacitance is detected by the capacitance detection means 6.

  The electrostatic capacity detection means 6 often detects a change in electrostatic capacity by converting it into a change in DC voltage, but is not limited thereto.

  About the induction heating apparatus comprised as mentioned above, the operation | movement and an effect | action are demonstrated below.

  When the user instructs the start of heating through the operation unit 8, the heating control unit 4 operates the inverter circuit 7 to supply a high-frequency current to the heating coil 3. Thereby, a high frequency magnetic field is generated from the heating coil 3 and heating of the cooking vessel 1 is started.

  The heating control unit 4 controls the inverter circuit 7 so that the heating power set by the user is obtained by operating the operation unit 8. Specifically, for example, an input current of the inverter circuit 7 is detected, and the detected value is input to the heating control unit 4.

  The heating control unit 4 compares the thermal power set by the user with the input current of the inverter circuit 7 and changes the operation state of the inverter circuit 7. By repeating such an operation, the heating control unit 4 operates to control the heating power set by the user and maintain the heating power.

  In this way, when the cooking container 1 is heated, the cooking object in the cooking container 1 may reach the boiling point, and the cooking object may be spilled out of the cooking container 1.

  At that time, if the heating is continued without reducing the heating power, the cooking object spills from the cooking vessel 1 one after another, and the operation unit 8 is hot and cannot be operated due to the operation unit 8. There is a possibility that problems such as being unable to clean due to the food to be cooked will occur.

  In addition, the food to be cooked spilled from the cooking container 1 onto the top plate 2 may stick to the top plate 2 when heat is applied.

  However, when a change in the capacitance detected by the capacitance detecting means 6 is detected, the heating power is reduced or the heating is stopped to prevent the spilling from continuing, and the food to be cooked adheres to the top plate 2. You can prevent it from happening.

  When realizing such an induction heating device, energy is injected into the capacitance detecting means 6 under the influence of an electric field generated during induction heating, and the electrode 5 and the object to be cooked are originally detected. The capacitance may not be detected accurately.

  FIG. 2 is a diagram showing a capacitance detection result of the capacitance detection means of the induction heating apparatus in the first embodiment of the present invention.

  FIG. 2 (a) shows an example when it is not affected by the electric field. Even when induction heating is started with Ta, the detected value maintains A before the start of heating. Then, when the spilling occurs at Tb and the heated object covers the electrode 5, the electrostatic capacity increases, and the detection value of the electrostatic capacity detecting means 6 for detecting it decreases.

  This is because the capacitance detection means 6 is configured to observe the impedance change due to the increase in the capacitance of the electrode 5 by resistance partial pressure, but is not limited to such a configuration.

  Then, after Tc, as the spilled heated object moves, the manner of application onto the electrode 5 is different, and it can be seen that the capacitance changes and the detection value gradually changes.

  On the other hand, an example affected by the electric field is shown in FIG. The detection value that was A before heating starts increases to C when induction heating is started with Ta. This is because the detection of the capacitance detection means 6 does not increase because the stray capacitance formed in the electrode 5 decreases, but energy is injected through the electrode 5 from the electric field generated by starting induction heating. As a result, it is considered that the detection value of the capacitance detection means 6 has increased.

  When the heated object to be spilled by Tb covers the electrode 5, the heated heated object plays the role of an antenna and is more affected by the electric field than before the spilled, and the capacitance detecting means The detection value of 6 increases significantly to D.

  When the induction heating is stopped at Td, the detection value of the capacitance detection means 6 is not affected by the electric field, and only the capacitance formed by the electrode 5 is obtained. At that time, since the electrostatic capacity is increased by covering the electrode 5 with the object to be heated which was not before the start of heating, the detection value is E which is smaller than the detection value A before the start of heating. Yes.

  Thus, when not affected by the electric field, the detection value of the capacitance detection means 6 varies faithfully with respect to the change in capacitance formed by the electrode 5 as shown in FIG.

  However, as shown in FIG. 2B, the electrostatic capacitance detection means 6 is not only based on the capacitance formed by the electrode 5 but also by the magnitude of energy injected through the electrode 5 from the electric field when affected by the electric field. The detected value fluctuates.

  Note that FIG. 2 is an example of spillage and does not necessarily indicate the change in the detected value as shown in FIG.

  The influence of such an electric field is determined by various factors. One of them is a wiring for connecting the electrode 5 and the capacitance detecting means 6. The influence of the electric field varies depending on the length of the wiring and how it is routed. For example, if the wiring is routed in a shape close to a circle, the wiring functions as a loop antenna. In addition, it is easy to function as an antenna even when the wiring is long.

  Therefore, in the present invention, as an induction heating apparatus in which the wiring length connecting the electrode 5 and the capacitance detecting means 6 is substantially equal, the influence of the electric field is made to be the same level in the plurality of electrodes 5, so Can be the same.

By doing so, it is possible to prevent the sensitivity from being different for each electrode for detecting the spillage and to give the user a sense of incongruity, and to provide an easy-to-use induction heating device.

  FIG. 3 is a layout diagram when the wiring lengths connecting the electrodes of the induction heating apparatus and the capacitance detection means in the first embodiment of the present invention are the same.

  In FIG. 3, three electrodes 5 (5aa, 5ab, 5ac) having the same area are arranged for one induction heating unit. And the electrostatic capacitance detection means 6 (6aa, 6ab, 6ac) which detects the electrostatic capacitance of the electrode 5 is distribute | arranged to the vicinity of each electrode 5, and equidistant.

  Such an arrangement not only has the same wiring length for the three electrodes 5, but also has the advantage that it is not easily affected by an electric field because the wiring length itself is short. However, since the electrostatic capacity detection means 6 are scattered, the layout inside the apparatus is complicated, and the cost increases by configuring the electrostatic capacity detection means 6 separately, resulting in an increase in cost. There are also disadvantages.

  FIG. 4 is a layout diagram when the electrostatic capacity detection means of the induction heating apparatus in the first embodiment of the present invention is collected in one place, and shows only one induction heating unit.

  In FIG. 4, each electrostatic capacitance detection means 6 is arranged in the vicinity. With such an arrangement, a plurality of capacitance detecting means 6 can be integrated, the layout inside the device can be simplified, and cooling inside the device is advantageous and reliable. A high induction heating device can be realized.

  Moreover, since it can be manufactured at low cost, it also provides benefits to the user.

  In such a layout, if the electrodes 5 and the capacitance detecting means 6 are wired at the shortest distance, the way of receiving the influence of the electric field differs for each electrode, which gives the user a sense of incongruity. Therefore, it is necessary to adjust the detection sensitivity of the capacitance detection means 6 for each electrode 5.

  Therefore, by making the wiring length the same for every electrode 5 as shown in FIG. 4, the influence of the electric field is the same, and the same even if the detection sensitivity of the spillage or the electrode 5 changes. Therefore, it is possible to realize an induction heating device that can be used with peace of mind by the user.

(Embodiment 2)
Next, a second embodiment of the present invention will be described. Description of the same parts as those in the first embodiment will be omitted, and only differences will be described.

  In the present embodiment, the plurality of electrodes 5 arranged on the lower surface of the top plate 2 are configured by printing a conductive material on the top plate 2.

  Since the electrode 5 functions as an electrode if it is a conductive material, for example, a metal plate may be disposed on the lower surface of the top plate. However, the capacitance generated in the electrode 5 is extremely small. For this reason, the capacitance value changes even with a small factor. For example, the capacitance value changes even if there is a gap between the metal plate and the top plate.

  Therefore, in order to stably acquire the capacitance value, the conductive material is printed on the back surface of the top plate 2 to configure the electrode 5. By doing so, since the distance between the top plate 2 and the electrode 5 is kept constant, the capacitance value is stabilized.

  Therefore, it is possible to stably detect spillage. Further, since the assembly of the equipment is simplified, it can be manufactured at a low cost, which brings benefits to the user.

(Embodiment 3)
Next, a third embodiment of the present invention will be described. Description of the same parts as those in the first embodiment will be omitted, and only differences will be described.

  In the present embodiment, the wiring connecting the electrode 5 and the capacitance detecting means 6 is configured by printing a conductive material on the top plate 2.

  Since the wiring for connecting the electrode 5 and the capacitance detecting means 6 is only required to be electrically connected, it may be connected by a vinyl composite wire or the like. However, actually, as described in the second embodiment, the capacitance generated in the electrode 5 is extremely small, and thus the capacitance may be affected even if the wiring length is different or the routing state is changed.

  In such a state, there is a possibility that the detection accuracy of the spillage varies. Therefore, it is desirable that the wiring has a stable length and routing.

  Therefore, in order to stably acquire the capacitance value, a conductive material is printed on the back surface of the top plate 2, and the capacitance is obtained by electrically connecting the electrode 5 and the capacitance detection means 6. The value of becomes stable. Therefore, it is possible to stably detect spillage. Further, since the assembly of the equipment is simplified, it can be manufactured at a low cost, which brings benefits to the user.

(Embodiment 4)
Next, a fourth embodiment of the present invention will be described. Description of the same parts as those in the first embodiment will be omitted, and only differences will be described.

  In the present embodiment, when the wiring length for electrically connecting the electrode 5 and the capacitance detection means 6 is different, the threshold value for the capacitance detection means 6 to detect a change in capacitance is determined according to the wiring length. This is an induction heating device to be set.

  FIG. 5 is a layout diagram showing different wiring lengths for connecting the electrodes of the induction heating apparatus and the capacitance detecting means in the present embodiment. In FIG. 5, only one induction heating unit is shown. As described in the first embodiment, when the electrostatic capacitance detection means 6 are arranged in a scattered manner for each electrode as shown in FIG. 3, the wiring length itself can be shortened, so that it is difficult to be affected by the electric field. Have advantages.

  However, since the capacitance detection means 6 are scattered, the layout inside the apparatus is complicated, and the capacitance detection means 6 is separately configured to increase the cost, resulting in an increase in cost. There are disadvantages.

  Therefore, the arrangement of the capacitance detection means 6 as shown in FIG. 4 and FIG. 5 can simplify the layout inside the device and reduce the manufacturing cost and provide it at low cost.

  In that case, since the distance between the electrode 5 and the capacitance detection means 6 is different, the first embodiment is configured to have the same wiring length.

In this case, the influence of the electric field is the same, and the sensitivity is the same for each electrode 5 when the capacitance detection means 6 detects a change in the capacitance value. do it.

  However, when the wiring between the electrode 5 and the capacitance detecting means 6 is made to be in a shape close to the shortest distance as shown in FIG. 5, the wiring length differs for each electrode. In this case, the influence of the electric field is different and the sensitivity varies.

  FIG. 6 shows an example of detection of spillage in the induction heating apparatus according to the fourth embodiment of the present invention. FIG. 6A shows a change in the detection value of the capacitance detection means 6 when not affected by the electric field. The detected value is A before the start of heating. Then, the heating starts at Ta, and when the spilling occurs at Tb and the object to be heated covers the electrode 5, the detection value decreases, and at Tc, the detection value decreases to B.

  Then, when the spilled heated object gradually moves and the covering method on the electrode 5 changes, the detection value gradually increases. In such a change in the detection value, in this example, the spilling occurs and the capacitance of the object to be heated covers the electrode 5 to change the capacitance. The detection value of the capacitance detection means 6 is from A to B. The amount of change is E.

  Therefore, if there is a change equal to or less than E from the value before spilling, it can be determined that spilling has occurred. Specifically, for example, assuming that the threshold value is E / 2, if the detection value of the capacitance detection means 6 is equal to or less than (A−E / 2), it can be determined that the spill is over.

  Next, FIG. 6B is an example in the case of being slightly affected by the electric field. The detection value before the start of heating is A, but when the heating is started with Ta, the detection value is slightly increased by injecting energy from the electric field.

  When the spilling occurs at Tb and the object to be heated covers the electrode 5, the detection value decreases, and at Tc, the detection value decreases to C. Then, when the spilled heated object gradually moves and the covering method on the electrode 5 changes, the detection value gradually increases.

  In such a change in the detection value, in this example, the spilling occurs, and the capacitance is changed by the object to be heated covering the electrode 5, and the detection value of the capacitance detection means 6 decreases to C. The amount of change is F.

  In FIG. 6B, the amount of change after the start of heating is used, but the amount of change from the detected value (A) before the start of heating may be used. As a determination, if there is a change of F or less, it can be determined that a spill has occurred.

  The amount of change F in FIG. 6B is smaller than the amount of change E in FIG. This is because in FIG. 6B, it is affected by the electric field. As described in the first embodiment, when the capacitance detecting means 6 is configured to observe the impedance change due to the increase in the capacitance of the electrode 5 by the resistance partial pressure, the spilling occurs and the heated object is the electrode 5. When the surface is covered, the detection value of the capacitance detection means 6 decreases. On the other hand, when it is affected by the electric field, energy is injected and the detection value increases.

  When Ta is detected, the detection value rises only due to the influence of the electric field, whereas when Tb, two events in which the capacitance increases due to the influence of the electric field and the occurrence of spillage and the detection value decreases overlap, The amount of change decreases.

FIG. 6C shows a case where the influence of the electric field is further increased, and the amount of change further decreases to G alone. As described above, since the amount of change in the detected value varies depending on how the electric field is affected, the threshold value for detecting the occurrence of spillage must be optimized.

  For example, when the threshold is set to E / 2 based on FIG. 6A, only G changes in FIG. 6C, so that it cannot be detected if E / 2> G.

  The level affected by the electric field varies depending on the wiring length in this embodiment. As the wiring length becomes longer, it becomes more susceptible to the influence of the electric field, so the amount of change when spilled is reduced. Therefore, by determining the threshold value from the relationship between the wiring length and the amount of change, it is possible to reliably detect the overflowing.

(Embodiment 5)
Next, a fifth embodiment of the present invention will be described. Description of the same parts as those in the first embodiment will be omitted, and only differences will be described.

  In this Embodiment, when the area of the some electrode 5 differs, it is set as the induction heating apparatus which sets the threshold value in which the electrostatic capacitance detection means 6 detects a change of an electrostatic capacitance according to an electrode area.

  In the fourth embodiment, it has been described that the influence of the electric field is different depending on the wiring length, but the influence of the electric field is also different when the area of the electrode is different. Accordingly, by determining the threshold value from the relationship between the electrode area and the amount of change, it is possible to reliably detect the spillage.

(Embodiment 6)
Next, a sixth embodiment of the present invention will be described. Description of the same parts as those in the first embodiment will be omitted, and only differences will be described.

  In the present embodiment, the induction heating apparatus is configured such that the metal portion is disposed in the vicinity of the plurality of electrodes 5.

  When the spilling occurs and the object to be heated covers the electrode 5, the detection value of the capacitance detecting means 6 is affected by the influence of the electric field. At that time, if the heated object to be spilled covers the metal part, the influence of the electric field can be reduced.

  FIG. 7 is a diagram showing a layout example of the metal part in the vicinity of the electrode of the induction heating device in the fifth embodiment of the present invention, and is a view of the top plate 2 as seen from the back surface.

  In FIG. 7, the top surface of the top plate 2 that forms the outline of the induction heating device has no irregularities and is easy to clean, which is an advantage of the induction heating device. The back surface of the top plate 2 is provided with a metal part around it for fixing the glass and reinforcing the strength.

  FIG. 8 is a diagram showing an example of spilling on the metal part in the vicinity of the electrode of the induction heating device according to Embodiment 6 of the present invention. FIG. 8A shows the case where the object to be heated does not come on the metal part 9, and FIG. 8B shows the case where the object to be heated comes on the metal part 9.

  In FIG. 8 (a), the heated object in the spilled cooking container 1 covers the electrode 5 and is also connected to the cooking container 1. At this time, a capacitor is formed by the heated object spilled over the electrode 5, and the capacitance detecting means 6 detects the capacitance.

At this time, when an electric field is generated by performing induction heating, the energy injected from the electric field is superimposed on the detection value of the electrostatic capacitance detection means 6 via the electrode 5, and the change in the electrostatic capacitance to be detected can be understood. It becomes difficult.

  At this time, the degree of influence of the electric field is determined by various factors such as the electrode area, the wiring length, and the wiring routing.

  However, in FIG. 8B, the heated object is also covered on the metal part 9. In this case, when the electrode 5 and the heated object to be spilled are formed, not only the capacitor but also the capacitor formed by the metal part 9 and the heated object to be spilled exist, and these are the same spilled object to be heated. Connected.

  In this state, when an electric field is generated by performing induction heating, the energy injected from the electric field is released to the metal part side and affects the detection value of the capacitance detection means 6 connected to the electrode 5. There is nothing.

  Therefore, it is possible to detect a change in capacitance without being affected by an electric field, and it is possible to accurately detect a spill.

  In order to further enhance the effect, it is necessary to cover the heated object that has been spilled over both the electrode 5 and the metal part 9, so that the metal part 9 is preferably in the vicinity of the electrode 5. It is desirable that the electrode 5 and the metal part 9 are arranged at the same distance.

  Further, it is more effective that the metal portion 9 has the same potential as a stable potential that does not vary, such as the ground of the circuit.

  By adopting such a configuration, the plurality of electrodes are not affected by different levels of electric fields, and the spillage can be detected more reliably.

  As described above, the induction heating apparatus according to the present invention ensures that the food to be spilled is reliably spilled by making the electrode area and wiring length for detecting spillage the same, or setting the detection threshold accordingly. Since it has the effect of preventing the spilling from being continued while maintaining the cooking performance, it is effective for cleaning of the induction heating device used in general households.

DESCRIPTION OF SYMBOLS 1 Cooking container 2 Top plate 3 Heating coil 4 Heating control part 5 Electrode 6 Capacitance detection means 9 Metal part 10 Object to be heated

Claims (8)

A top plate on which the cooking container is placed; a heating coil that generates an induction magnetic field to heat the cooking container; and a heating control unit that controls the heating power of the cooking container by controlling a high-frequency current supplied to the heating coil; A plurality of electrodes of the same area disposed on the lower surface of the top plate, and a capacitance detecting means for detecting a change in capacitance generated in the electrodes due to the food to be cooked on the top plate, When the capacitance detecting means detects that there is a change in capacitance, the heating control unit controls the heating power to change so that the electrode and the capacitance detection An induction heating device in which the lengths of wires connecting the means are substantially equal. The induction heating apparatus according to claim 1, wherein the plurality of electrodes arranged on the lower surface of the top plate is configured by printing a conductive material on the top plate. The induction heating apparatus according to claim 1, wherein the wiring connecting the electrode and the capacitance detecting means is configured by printing a conductive material on the top plate. A top plate on which the cooking container is placed; a heating coil that generates an induction magnetic field to heat the cooking container; and a heating control unit that controls the heating power of the cooking container by controlling a high-frequency current supplied to the heating coil; A plurality of electrodes of the same area disposed on the lower surface of the top plate, and a capacitance detecting means for detecting a change in capacitance generated in the electrodes due to the food to be cooked on the top plate, When the capacitance detecting means detects that there is a change in capacitance, the heating control unit controls the heating power to change so that the electrode and the capacitance detection An induction heating device that sets a threshold value for detecting a change in capacitance by the capacitance detection means according to the wiring length when the wiring lengths connecting the means are different. A top plate on which the cooking container is placed; a heating coil that generates an induction magnetic field to heat the cooking container; and a heating control unit that controls the heating power of the cooking container by controlling a high-frequency current supplied to the heating coil; A plurality of electrodes arranged on the lower surface of the top plate, and a capacitance detecting means for detecting a change in capacitance generated in the electrodes when an object to be cooked adheres to the top plate, When it is detected that there is a change in capacitance by the capacitance detection means, the heating controller controls the heating power to be changed, and when the areas of the plurality of electrodes are different, An induction heating apparatus in which a capacitance detection unit sets a threshold value for detecting a change in capacitance according to an electrode area. A top plate on which the cooking container is placed; a heating coil that generates an induction magnetic field to heat the cooking container; and a heating control unit that controls the heating power of the cooking container by controlling a high-frequency current supplied to the heating coil; A plurality of electrodes arranged on the lower surface of the top plate, and a capacitance detecting means for detecting a change in capacitance generated in the electrodes when an object to be cooked adheres to the top plate, When the capacitance detecting means detects that there is a change in the capacitance, the heating control unit controls the heating power to be changed, and a metal unit is provided in the vicinity of the plurality of electrodes. An induction heating device configured to be arranged. The induction heating apparatus according to claim 6, wherein the metal portion has a substantially equal distance from the electrode. The induction heating apparatus according to claim 6 or 7, wherein the metal part is connected to a stable potential of the heating control part or the capacitance detection means.

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