WO2011155222A1

WO2011155222A1 - Induction cooker

Info

Publication number: WO2011155222A1
Application number: PCT/JP2011/003308
Authority: WO
Inventors: 武平　高志; 小笠原　史太佳; 雅志木下; 祐史山本
Original assignee: パナソニック株式会社
Priority date: 2010-06-10
Filing date: 2011-06-10
Publication date: 2011-12-15
Also published as: JPWO2011155222A1

Abstract

Disclosed is an induction cooker configured to begin a timer count if the rate of change of a capacitance signal from a reference value is greater than or equal to a reference value updating rate of change, to continue the count until a predetermined maximum count time elapses if the rate of change continues to be within a range greater than or equal to the reference value updating rate of change and less than or equal to a boil-over determination rate of change during a period from when the count began to a first predetermined time, and to restart the reference value updating process once the timer counted to the maximum counting time.

Description

Induction heating cooker

The present invention relates to an induction heating cooker, and particularly to an induction heating cooker having a function of detecting a spill from a heated container such as a pan during cooking.

In a conventional induction heating cooker, the detection of boiling over is performed by providing a plurality of electrodes on the outer periphery of the heating coil as described in Japanese Patent Application Laid-Open No. 2008-159494 (Patent Document 1). It was done based on the change in capacitance.

FIG. 5 is a diagram showing a configuration of a conventional induction heating cooker described in Patent Document 1. In FIG. FIG. 6 is a graph showing a change in capacitance in an electrode for performing the overflow detection described in Patent Document 1.

As shown in FIG. 5, in the conventional induction heating cooker, a plurality of small disk-like electrodes 103 are concentrically distributed on the outer periphery of the heating coil 104. Each electrode 103 distributed is connected to a capacitance measuring circuit 106, and the capacitance between each electrode 103 and a surrounding dielectric such as air or a heating container is detected. . The conventional induction heating cooker configured as described above has a configuration in which the plurality of electrodes 103 are dispersedly arranged on the outer periphery of the heating coil 104, and thus is mounted on the heating coil 104 via a top plate (top plate). When liquid is spilled from the peripheral part of a heating container such as a pan placed, the liquid spilled exists on or near any of the electrodes 103. As a result, the capacitance of one of the electrodes 103 is changed by the spilled liquid, thereby detecting the spill. In a state where there is no spillage in the heating container at the time of heating, air having a relative dielectric constant of 1 exists mainly between the electrode 103 and the heating container in addition to the top plate. However, when spilling occurs, moisture intervenes between the electrode 103 and the heating container, and the capacitance increases rapidly. Therefore, it is possible to detect the spillage by detecting the capacitance of the electrode 103 as described above.

In the conventional induction heating cooker, when it is detected that the capacitance of the electrode 103 has suddenly increased (see FIG. 6), the control circuit 105 determines that it is spilled, and the power from the AC power supply 101 is input to the high frequency. The operation of the driving circuit 102 that generates electric power is stopped, or the current flowing through the heating coil 104 is reduced.

JP 2008-159494 A

As described above, it is possible to detect spillage by detecting the electrostatic capacity by using the electrodes 103 dispersedly arranged on the outer periphery of the heating coil 104, but the spilled menu, the shape of the pan, and the thermal power In some cases, the momentum is low and there is a pattern that spills slowly over time, the capacitance does not change abruptly, and the spillage detection may not be detected accurately. Moreover, if the threshold value of the change amount of the electrostatic capacitance is set to be small, erroneous detection due to touching the top plate occurs frequently, and even when the droplets adhere to the top plate, the spillage is detected and heating is stopped. For this reason, simply setting the threshold value for the amount of change in capacitance has resulted in a cooking device that is inconvenient for the user.

In an induction heating cooker, a top plate having a smooth surface and no unevenness is provided as a cooking surface, and is configured so that dirt generated by spilling can be easily wiped off. However, if a spill occurs, leaving it as it is will cause a safety problem if a large amount of spill occurs, and even if a small amount of spill occurs, it will dry on the top plate and stick Therefore, there is a problem that wiping becomes difficult. Therefore, when a spill occurs, it is important to notify the user immediately and stop the heating operation or reduce the heating. However, depending on the state of the spill, the cooking menu that causes the spill, the shape of the pan, and the thermal power, there may be a small amount of spill at a time and detection of the spill may not be possible. In addition, even if the amount of spillage is small, if it continues to spill over time, the amount of spillage will eventually spread so that it will spread over the top plate, and the product performance will not be satisfactory. Management) is a big problem.

An object of the present invention is to provide a highly reliable and safe induction heating cooker that can reliably detect the occurrence of spilling when a small amount of spilling in a heating container that occurs during cooking is continued. To do.

The induction heating cooker according to the first aspect of the present invention is:
A top plate on which the heating container is placed;
A heating coil provided below the top plate for inductively heating the heating container;
An inverter for supplying a high frequency current to the heating coil;
An electrode provided on the back surface of the top plate in the vicinity of the periphery of the heating coil;
A capacitance detector for detecting a capacitance of the electrode by supplying a high-frequency current to the electrode;
A storage unit for storing a reference value for measuring the amount of change in the capacitance;
A control unit that controls the output of the inverter to be a first set value set by an output setting unit;
After the amount of change of the capacitance with respect to the reference value exceeds the fixed amount of spillage, the spillover detection is performed to stop the heating operation or reduce the output of the inverter to a second set value lower than the first set value. And comprising
The overflow detection unit replaces the capacitance detected during the predetermined period with the reference value when the state in which the change amount is less than the reference value update change amount smaller than the fixed overflow change amount continues for a predetermined period. Perform the reference value update process stored in the storage unit,
When the change amount is equal to or greater than the reference value update change amount, the overflow detection unit prohibits the reference value update process, and the timer starts counting and starts counting for a first predetermined time. When the change amount is continuously greater than or equal to the reference value update change amount and within the change range less than or equal to the overflow determination change amount or within a change range narrower than the change range, a preset longer than the first predetermined time Continue counting until the maximum count time has elapsed,
The overflow detector is configured to resume the reference value update process when the timer counts up to the maximum count time.
The induction cooking device according to the first aspect configured as described above is reliable and safe for reliably detecting the occurrence of spillage when a small amount of spillage in the heating container that occurs during cooking continues. Become a highly functional cooker

In the induction heating cooker according to the second aspect of the present invention, the spillover detection unit according to the first aspect is configured to elapse a second predetermined time after the change amount is equal to or greater than the spillover confirmed change amount. Then, the heating is stopped or the output of the inverter is set to a second set value lower than the first set value. The induction cooking device according to the second aspect configured as described above can reliably detect the spilling and reduce or stop the heating output even when a small amount of spilling continues.

In the induction heating cooker according to the third aspect of the present invention, the overflow detection unit in the first aspect or the second aspect prohibits the reference value update process, and the amount of change is the reference value. The reference value update process is resumed when the amount of change is less than the update change amount. The induction heating cooker of the 3rd viewpoint comprised as mentioned above can prevent erroneous detection of the spilling by the fluctuation | variation of the electrostatic capacitance which can occur at the time of cooking, and a user can cook continuously.

According to the present invention, it is possible to provide an induction heating cooker that can accurately detect spillage in a heating container that occurs during an induction heating operation and that can greatly reduce erroneous detection of spillage.

The block diagram which shows the structure of the induction heating cooking appliance of Embodiment 1 which concerns on this invention. The top view which shows the various electrodes etc. which were formed in the top plate in the induction heating cooking appliance of Embodiment 1. The figure which shows an example (b) of the electrostatic capacitance detection signal (a) detected in the induction heating cooking appliance of Embodiment 1, and the heating output output from the inverter It is a diagram showing a state of a menu display unit of the operation unit and a display unit in the induction heating cooker of the first embodiment, and shows a procedure for setting Fukikobore detection operation It is a diagram showing a state of a menu display unit of the operation unit and a display unit in the induction heating cooker of the first embodiment, and shows a procedure for setting Fukikobore detection operation It is a diagram showing a state of a menu display unit of the operation unit and a display unit in the induction heating cooker of the first embodiment, and shows a procedure for setting Fukikobore detection operation It is a diagram showing a state of a menu display unit of the operation unit and a display unit in the induction heating cooker of the first embodiment, and shows a procedure for setting Fukikobore detection operation It is a diagram showing a state of a menu display unit of the operation unit and a display unit in the induction heating cooker of the first embodiment, and shows a procedure for setting Fukikobore detection operation Block diagram showing the configuration of a conventional induction heating cooker A graph showing the change in capacitance in detecting boiling over in a conventional induction heating cooker

Hereinafter, specific embodiments according to the induction heating cooker of the present invention will be described with reference to the accompanying drawings. The present invention is not limited to the specific configurations described in the following embodiments, and is based on the same technical idea as the technical idea described in the embodiment and the common general technical knowledge in this technical field. Is included.

(Embodiment 1)
FIG. 1 is a block diagram showing the configuration of the induction heating cooker according to the first embodiment of the present invention.

1, the induction heating cooker of Embodiment 1 includes a top plate (top plate) 2 on which a heating container (for example, a pan) 1 is placed, and a heating coil 3 for induction heating the heating container 1. , An inverter 4 for supplying high-frequency current to the heating coil 3, an AC power supply 6 for supplying power to the inverter 4 via a rectifier 5, an input current supplied from the AC power supply 6 via the rectifier 5, and heating from the inverter 4 A current detection unit 7 that detects an output current supplied to the coil 3, a drive control of the inverter 4 based on an input / output current detection signal from the current detection unit 7, a control unit 8 having a timer, and a top plate 2 A plurality of electrodes 9 pattern-printed on the back surface (the surface on which the heating container 1 is placed in FIG. 1 as the front surface, and the opposite surface), and the capacitance for detecting the capacitance of each electrode 9 Inspection Unit 10, a storage unit 12 that stores a capacitance detection signal detected by capacitance detection unit 10, an input / output current detection signal detected by current detection unit 7, and the like, a capacitance detection signal, and an input / output And a spill detector 11 that detects a spill state of the heating container 1 based on a current detection signal or the like.

In addition, in the induction heating cooker of Embodiment 1, the structure and function for detecting the spilling state in the heating container 1 are mainly demonstrated, and the function and structure for detecting other states, for example, heating Description of the state detection function other than the spilled state, such as detection when the container 1 is shifted, floated, burned, and a small load is placed on the top plate 2, is omitted, and also in the block diagram of FIG. Configurations other than the spilled state are omitted.

FIG. 2 is a plan view of the top plate 2 showing various electrodes formed by pattern printing using a conductive film on the top plate 2 in the induction heating cooker according to the first embodiment. The top plate 2 shown in FIG. 2 is formed of heat resistant glass, for example, crystallized glass. The top plate 2 is drawn with two

circle patterns

2a and 2b that indicate the heating position on which a heating container (for example, a pan or the like) 1 as an object to be heated is placed. For example, heating with a maximum output of 3 kW The position corresponding to the coil 3 is shown. In the first embodiment, a configuration having two heating coils 3 will be described. However, the number of heating coils 3 is not limited to two, and any number of heating coils 3 such as one, three, and four. The circle pattern and the electrode are formed according to the number of the heating coils 3.

As shown in FIG. 2, the top plate 2 in the induction heating cooker according to the first embodiment is provided with a plurality of operation electrodes 16 serving as operation switches for the user to set the operation of the induction heating cooker. ing. The position where the operation electrode 16 is provided is a region closer to the user side than the

circle patterns

2 a and 2 b on the top plate 2. In the following description, the user side in the top plate 2 is referred to as the near side, and the opposite is referred to as the back side. Further, at the position on the drawing shown in FIG. 2, the position on the top plate 2 is specified by referring to the left side and the right side of the top plate 2.

A plurality of electrodes 9 (blow-off detection electrodes 9a to 9g) are formed on the outer peripheral portions of the

circle patterns

2a and 2b. These electrodes 9 serve as state detection electrodes for detecting a spilled state or the like.

In the outer peripheral portion of the left circle pattern 2a in the top plate 2 shown in FIG. 2, the arc-shaped left rear electrode 9a along the annular shape of the circle pattern 2a is formed on the back side on the left side, and the circle pattern is formed on the front side on the left side. An arc-shaped left front electrode 9b along the circular shape of 2a and an arc-shaped left central electrode 9c along the circular shape of the circle pattern 2a are formed on the center side. The left rear electrode 9a, the left front electrode 9b, and the left center electrode 9c are configured to surround the outer periphery of the left circle pattern 2a. In addition,

connection terminals

19a, 19b, and 19c are formed at one end of each of the left rear electrode 9a, the left front electrode 9b, and the left center electrode 9c. These

connection terminals

19a, 19b, and 19c have a function of a detection terminal for detecting the overflowing state.

Similarly, also in the outer peripheral portion of the right circle pattern 2b, the arc-shaped right rear electrode 9d along the circular shape of the circle pattern 2b is provided on the right back side, and the circle pattern 2b is provided on the right front side. An arc-shaped right front electrode 9e along the shape and an arc-shaped right center electrode 9f along the ring shape of the circle pattern 2b are formed on the center side. These right rear electrode 9d, right front electrode 9e, and right center electrode 9f are configured to surround the outer periphery of the right circle pattern 2b. Further,

connection terminals

19d, 19e, and 19f are formed at one end of each of the right rear electrode 9d, the right front electrode 9e, and the right center electrode 9f. These

connection terminals

19d, 19e, and 19f have a function of a detection terminal for detecting the overflowing state.

A protection electrode 9g is provided at the center of the top plate 2, and is between the left center electrode 9c and the right center electrode 9f. From the left rear electrode 9a to the connection terminal 19a and the right rear electrode 9d A region between the wiring patterns led out to the connection terminal 19 d and a region parallel to the operation electrode 16 are arranged on the front side of the central portion of the top plate 2. The protective electrode 9g also has a connection terminal 19g formed at the end thereof, and has a function of a detection terminal for detecting a spilled state as with the other electrodes.

Moreover, in the induction heating cooker of Embodiment 1, the temperature detection part 17 which is a temperature sensor for detecting the temperature of the heating container 1, and the user setting the heating conditions of the induction heating cooker, etc. The operation unit 18 is provided. The temperature signal of the heating container 1 from the temperature detection unit 17 and the setting signal from the operation unit 18 are input to the control unit 8 to drive and control the inverter 4. Furthermore, the induction heating cooker according to the first embodiment is provided with a display unit 20 so that the heating conditions set by the user, the operation state of the induction heating cooker, and the like are displayed.

As shown in FIG. 1, the capacitance detection unit 10 includes a high frequency signal generation unit 13 that supplies a high frequency signal to each electrode 9, a rectification unit 14 that rectifies a high frequency current from each electrode 9, and a rectification unit 14. And a voltage detector 15 that detects the rectified DC voltage. The connection terminals (19a to 19g) of the electrodes 9 (9a to 9g) are supplied with a high-frequency signal from the high-frequency signal generation unit 13 of the capacitance detection unit 10, and the electrodes 9 (9a to 9g). ) Is electrically connected to the rectifying unit 14 in order to detect the capacitance.

In the induction heating cooker according to the first embodiment configured as described above, a pan or the like as the heating container 1 is placed at the position indicated by the

circle patterns

2a and 2b, and the user heats at the operation unit 18. Conditions etc. are set and induction heating operation is started. In the initial heating stage in which the induction heating operation is started, there is no spillage, and air having a relative dielectric constant of 1 is mainly present between the electrode 9 and the heating container 1. Thereafter, the induction heating operation continues, the contents of the heated heating chamber 1 becomes a boiling state, boiling over the possible state occurs. When the spilling occurs, a part of the content containing a lot of water having a relative dielectric constant of 80 exists around the electrode 9. As a result, the capacitance at the electrode 9 increases rapidly. If the spilled state continues, the increased state of the capacitance is continued to some extent according to the state at that time.

As described above, in the heating operation, it is not necessary to detect the spilled state until the contents of the heating container 1 reach the boiling possible temperature (the temperature at which the contents can be boiled). When the contents reach the boiling possible temperature, there is a possibility that spilling may occur, so it is necessary to always detect the spilling state. For this reason, in the induction heating cooker of Embodiment 1, it sets so that 5 seconds may be set as a fixed time from the start of heating to the boiling possible temperature, and the overflow detection operation is not performed for these 5 seconds. Has been. If the temperature of the heating container 1 or the like reaches the boiling possible temperature by the temperature detection unit 17 within 5 seconds from the start of heating, it is determined as abnormal and the heating operation is stopped.

In the induction cooking device of the first embodiment, the detection of the spilled state is performed based on the capacitance detection signal from the capacitance detection unit 10 and the input / output current signal from the current detection unit 7. 11 is performed.

FIG. 3 shows an example of the capacitance detection signal (FIG. 3A) detected in the induction heating cooker according to the first embodiment and the heating output (FIG. 3B) output from the inverter 4. Show. FIG. 3A is a waveform diagram showing an example of the capacitance detection signal (Vd) input from the capacitance detection unit 10 to the spill detection unit 11, and in FIG. Indicates a capacitance detection signal (voltage signal) output from the voltage detection unit 15, and the horizontal axis indicates the elapsed time. FIG. 3B shows the heating output (P) from the inverter 4 when the capacitance detection signal (Vd) shown in FIG. 3A is detected.

In the capacitance detection signal (Vd) shown in FIG. 3 (a), output from the voltage detection unit 15 is caused by the occurrence of spillage from the heating container 1 and the rapid increase in the capacitance of one of the electrodes 9. This shows a case where the electrostatic capacitance detection signal (Vd), which is a voltage signal that has been generated, is rapidly decreasing.

[Low-moistness detection operation]
Hereinafter, the overflow detection operation in the state of the capacitance detection signal (Vd) shown in FIG.

First, in the initial stage of the induction heating operation for starting heating the heating container 1 (not shown in FIG. 3A), the contents of the heating container 1 have not reached the boiling temperature, so there is no spilling and static There is no abrupt change in the capacitance detection voltage detected by the voltage detection unit 15 of the capacitance detection unit 10. As described above, the induction heating cooker according to the first embodiment is configured not to perform the overflow detection operation during the detection data invalid period that is a fixed time (for example, 5 seconds) from the start of the induction heating operation. Actually, processing for invalidating the detection data (change amount: ΔV) calculated in the overflow detection operation described below is performed.

When a certain amount of time (for example, 5 seconds) has passed since the induction heating operation started and the overflow detection operation is started, the detection signal input from each electrode 9 is rectified by the rectification unit 14 and input to the voltage detection unit 15. Is done. The capacitance detection signal (voltage signal: Vd) detected by the voltage detection unit 15 is constantly changing over time. For this reason, in the induction heating operation of the induction heating cooker according to the first embodiment, the voltage detection unit 15 always outputs the capacitance detection signal (Vd) from each electrode 9 to the boiling detection unit 11.

The spill detector 11 detects a capacitance detection signal (Vd) indicating the capacitance of each electrode 9 input from the voltage detector 15 of the capacitance detector 10 at regular intervals. In the overflow detector 11, for example, an average value is calculated every predetermined number of times (for example, 8 times) from a voltage signal (voltage value) detected every 20 ms, and the calculated average value is used for the detection period. The capacitance signal (Vc) in (first predetermined period: for example, 1 second) is used. The capacitance signal (Vc) calculated as described above is subjected to arithmetic processing in the spill detector 11 to determine the presence or absence of a spill state.

The graph shown in FIG. 3A shows the capacitance detection signal (Vd) output from the voltage detection unit 15, and this capacitance detection signal (Vd) is output from the overflow detection unit 11. Since the signal changes in substantially the same manner as the capacitance signal (Vc) to be used, the capacitance signal (Vc) will be described with reference to the graph shown in FIG.

[When the change amount of the capacitance signal (Vc) is equal to or less than the first change amount: the reference value update change amount (ΔV1)]
In the overflow detector 11, the capacitance signal (Vc (1)) detected at the beginning of the overflow detection operation is registered in the storage unit 12 as a reference value (Vo). Note that a preset value may be used for the first reference value (Vo). The electrostatic capacitance signal (Vc (2)) detected for the second time is compared with the registered reference value (Vo), and the amount of change (ΔV (2)) from the reference value (Vo) is detected. The If the detected change amount (ΔV (2)) is less than a first change amount (ΔV1; for example, 3 digits) that is a preset reference value update change amount, the capacitance signal (Vc ( 2)) is registered in the storage unit 12 as a reference value (Vo). In this way, the capacitance signal (Vc (n)) is compared with the reference value (voltage signal) which is the previously detected capacitance signal (Vc (n−1)), and the change amount (ΔV (N)) is detected and compared with a first change amount that is a reference value update change amount as a threshold value. Here, “Vc (n)” indicates a capacitance signal detected at the present time.

Therefore, if the change amount (ΔV (n)) of the current capacitance signal (Vc (n)) is less than the first change amount (ΔV1), the capacitance signal (Vc (n)) at that time is the same. It is registered in the storage unit 12 as a reference value (Vo), and is compared with a capacitance signal (Vc (n + 1)) detected next time. As described above, the latest reference value (Vo) is always sequentially stored in the storage unit 12 during the period in which the capacitance signal (Vc) is gradually changing. In the overflow detection operation, the reference value update operation described above is sequentially performed. If the change amount (ΔV (n)) becomes equal to or greater than the first change amount (ΔV1), the control unit 8 uses a timer. Start counting. When the change amount (ΔV (n)) stays within the first change range (CL1) within 5 seconds from the start of counting, the reference value (Vo) at the start of the timer count is stored in the storage unit 12, The timer continuously counts and stops the reference value update operation.

In the induction heating cooker of the first embodiment, the first change range (CL1) for determining whether or not to update and register as the reference value (Vo) is the first change as shown in FIG. The amount (ΔV1) is not less than the maximum value of the reference value update change amount, and is in a range up to the maximum value (ΔV) of the second change amount (ΔV2), which is an overflow determination change amount described later. In the first embodiment, the specific range of the first change range (CL1) is “3 to 12 digits”. Here, “digit” indicates 8 bit (255 digit) resolution, and 1 bit is 0.0195V.

As described above, in a normal induction heating operation in which no abnormal state has occurred, that is, in a state in which the capacitance of the electrode 9 does not change rapidly, the current capacitance signal (Vc (n)) and the previous detection are performed. Is compared with the reference value (Vo) which is the capacitance signal (Vc (n−1)), and the change amount is less than the first change amount (ΔV1: for example, 3 digits) (excluding the boundary point). Therefore, the capacitance signal (Vc (n)) detected at that time is newly registered as a reference value (Vo) and recorded in the storage unit 12. Similarly, when the change amount stays within the first change range (CL1) for 5 seconds from the start of the timer count, the reference value (Vo) is newly registered, and the timer count is cleared. Thus, in the induction heating cooker of Embodiment 1, in the normal induction heating operation, the detected capacitance signal (Vc) is the latest reference value (Vo) every detection period (for example, 1 second). ).

[When the timer count continues and the amount of change in the capacitance signal (Vc) exceeds the third change amount (ΔV3), which is the determined change amount)
Next, in the spillover detection unit 11, the capacitance signal (Vc (n)) is compared with the stored reference value (Vo) at the point A at the start of the timer count, and the third change that is the spillover definite change amount. The operation in the case where the amount has changed to the amount (ΔV3) or more will be described.

In the graph of FIG. 3A, when the electrostatic capacitance detection signal (Vd), that is, the electrostatic capacitance signal (Vc) exceeds the third variation (ΔV3), which is the determined amount of overflowing indicated by the point B. The induction heating cooker according to the first embodiment enters the spilling confirmation waiting period, and waits for 2 seconds (second predetermined time) while continuing the heating. Since the capacitance signal (Vc (n)) detected at the point B is equal to or greater than the third change amount (ΔV3) compared to the stored reference value (Vo) at the point A, which is the reference value, the timer count The electrostatic capacitance signal (point A) at the start continues to be registered as the reference value (Vo) as it is. In FIG. 3A, the reference value (Vo) at point A is fixed as the reference value. Thus, the reference value (Vo) is fixed during the reference value update stop period, and the amount of change with respect to the fixed reference value (Vo) is calculated. In the first embodiment, the third change amount (ΔV3), which is a definite amount of overflowing change, is set to “15 digits”.

Even when the change amount (ΔV (n)) of the capacitance signal (Vc) exceeds the first change amount (ΔV1), the detected capacitance signal is detected next. When (Vc (n + 1)) returns within the first change amount (ΔV1) compared to the previously stored reference value (Vo), the reference value update stop period is canceled and the timer count is also cleared. The reference value is updated without being stored until the timer count condition is satisfied again.

[When the overwriting confirmation waiting period has elapsed]
When the electrostatic capacitance signal (Vc) becomes equal to or more than the third change amount (ΔV3), which is the spillage confirmation change amount, during the spillage confirmation standby period, the predetermined heating is continued for 2 seconds, and the heating is stopped after 2 seconds, Notification of spillage detection.

In the induction heating cooker according to the first embodiment, in the overflow detection period in which the detected electrostatic capacity signal (Vc (n)) is equal to or greater than the third variation (ΔV3), which is the final variation, the inverter 4 The heating output is stopped from the first set value (P1: for example, 3 kW) registered at the time of setting the induction heating operation condition to the second set value (P2: for example, 0 W).

As described above, the induction heating cooker according to the first embodiment has the first predetermined amount from when the change amount of the capacitance signal (Vc) exceeds the first change amount (ΔV1) that is the reference value update change amount. In the spillage determination period starting after the elapse of time (5 seconds), the induction heating operation is stopped or reduced when the detection of the spillover is confirmed. This state is shown in FIGS. 3A and 3B. As shown in FIGS. 3A and 3B, when the change amount of the capacitance signal (Vc) from the reference value (Vo) is equal to or greater than the first change amount (ΔV1) that is the reference value update change amount. When the timer count is started and within the first change range (CL1) and the timer count reaches the first predetermined time, the reference value update period ends and the reference value update stop period starts. The first change range (CL1) is a timer count continuation determination period, is equal to or greater than the maximum value of the first change amount ΔV1 that is the reference value update change amount, and is a second change amount ΔV2 that is the overflow determination change amount (for example, The range is less than the maximum value of 12 digits).

In the reference value update stop period, the capacitance signal (capacitance voltage at point A in FIG. 3A) detected at the start of the timer count is stored and used as the reference value (Vo). With this stored reference value (Vo), the overflow determination is confirmed after a second predetermined time (2 seconds) from when the detected capacitance signal (Vc) exceeds the third change amount (ΔV3). Then, the heating output is stopped.

In the induction heating cooker according to the first embodiment, when the detected amount of change in capacitance is equal to or greater than the reference value update change amount (ΔV1), the spill detector 11 prohibits the reference value update process, and the timer Starts counting, and during the first predetermined time (for example, 5 seconds) from the start of counting, the detected change amount is continuously greater than or equal to the reference value update change amount (ΔV1), If the current value is within the change range of (ΔV3) or less, or the reference value update change amount (ΔV1) that is narrower than this change range and is within the change range of the overflow determination change amount (ΔV2), the count is continued. The count is continued until a preset maximum count time (for example, 60 seconds) longer than the predetermined time elapses. The overflow detection unit 11 resumes the reference value update processing when the timer counts up to the maximum count time.

[Menu display]
4A to 4E show the states of the operation display unit 18 and the menu display unit of the display unit 20 in the induction heating cooker according to the first embodiment, and show the procedure for setting the overflow detection operation.

FIG. 4A is a display state diagram of the menu display unit in the operation unit 18 and the display unit 20 when the user sets the heating conditions before the induction heating operation of the first embodiment is performed. As shown in FIG. 4A, only the “menu” operation switch is displayed in the menu display section. When the user selects (presses) the “menu” mark, as shown in FIG. 4B, in addition to the “menu”, “heating”, “pan mark”, “fried food”, “baked food”, “kettle mark”, “Koketsu” and “Off / Start” marks are displayed. At this time, only the “heating” mark blinks.

In the state shown in FIG. 4B, "off / start" select mark (pressing) Then, together with the induction heating operation is started, burnt detection operation is started. The burning detection operation is to detect burning of the contents of the heating container 1 and is detected by the temperature detection unit 17 based on information such as a rapid temperature rise. During this induction heating operation, only the burn-out detection operation is activated, and the overflow detection operation is not started.

In the state shown in FIG. 4B, when the “menu” mark is selected (pressed), a menu display portion is displayed as shown in FIG. 4C. As shown in FIG. 4C, “Fukibokore” mark is newly displayed from the menu display section shown in FIG. 4B, and “Heating” and “Pot mark” are blinkingly displayed. That is, when the user selects (presses) the “cut / start” mark in this state, the induction heating operation is started, and the burn-in detection operation and the overflow detection operation are started. FIG. 4D shows the display state of the menu display section during the induction heating operation. As shown in FIG. 4D, “heating”, “pan mark”, “menu”, and “off / start” are displayed during the induction heating operation, and the user can change the menu at any time during the induction heating operation. It is possible to stop the heating operation.

As described above, during the induction heating operation in which the overflow detection operation is set, as a result of the above-described overflow detection operation, when the overflow detection is confirmed and the occurrence of the overflow is detected, as shown in FIG. “Blowout” flashes. In addition, in the induction heating cooker of Embodiment 1, it is the structure by which "Fukikobo" flashes and is displayed on the menu display part when it detects the overflow, but "Fukikobo" flashes and is in the state of being overflowing. It is good also as a structure alert | reported by an audio | voice.

In the menu display section of the induction heating cooker according to the first embodiment, every time the “menu” mark is pressed and selected, “heating”, then “fried food”, “baked food”, “kettle mark”, And "heating" blinks sequentially, and it is comprised so that a to-be-heated object may be selected. The “kettle mark” indicates a kettle operation.

The operation unit 18 in the induction heating cooker according to the first embodiment includes operation switches (left and right movements) required in the induction heating cooker such as selection of a heater, temperature setting (heating power adjustment), timer setting, and the like. Arrow marks to indicate, marks indicating increase / decrease (+,-), etc.) are provided.

As described above, the induction heating cooker of the present invention is based on signals from a plurality of arc-shaped electrodes provided on the back surface of the top plate in the vicinity of the periphery of the heating coil, as specifically exemplified in the embodiment. Therefore, it is possible to accurately detect the amount of change in the capacitance generated in the electrode, greatly reduce the erroneous detection of spillage in the heating container that occurs during induction heating operation, and reliably detect the occurrence of spillage. It becomes an induction heating cooker with high reliability and safety.

Also, the induction heating cooker of the present invention can improve the accuracy of detection of spilling without momentum, and can reliably detect spilling regardless of the type of pan, cooking menu, and thermal power. Furthermore, the induction heating cooker of the present invention can suppress the frequency of erroneous detection of spilling by making it a two-step detection even with detection with a small change amount, and reliably detect the occurrence of spilling. Can do.

The induction heating cooker of the present invention includes a top plate on which a heating container is placed, a heating coil that is provided below the top plate and induction-heats the heating container, an inverter that supplies high-frequency current to the heating coil, and a heating coil A plurality of electrodes provided on the back surface of the top plate in the vicinity of the periphery, a capacitance detector for detecting a capacitance of the electrodes by supplying a high frequency signal to the electrodes, and using the detected capacitance as a reference value Detectable by a storage unit that can be stored, a control unit that controls the heating output of the inverter to be a first set value (P1: for example, 3 kW or less) set at the start of induction heating, and a capacitance detection unit When the change amount of the capacitance with respect to the reference value is the first change amount (ΔV1: for example, 3 digits) which is the reference value update change amount, the timer is started, and the change amount is within the first change range. (CL1: For example, 3 to 12 digits) If the timer continues for a predetermined time, the timer counts continuously for a predetermined time, and the reference value at that time is stored in the storage unit until the timer count ends, and from the stored reference value And a spillover detector that stops heating to a preset second set value (P2: 0 W, for example) when the third change amount (ΔV3: 15 digits, for example), which is the spilling fixed change amount, is provided. .

In addition, in the induction heating cooker of the present invention, the spill detector is a timer continuation condition within the first change range (CL1) (not including the boundary point) for a first predetermined time (for example, 5 seconds), If it stays, the timer count is continued, and if it falls outside the first change range (including the boundary point) within the first predetermined time, the timer count is cleared and the reference value is updated. At this time, if the timer count continues to be a condition, the heating is stopped or decreased when the third change amount (ΔV3) or more is reached by the end of the timer count (for example, 60 seconds), It is configured to notify the detection of overflowing.

The induction heating cooker of the present invention configured as described above can detect overflowing spillage over time, and improve the accuracy of detection of spillage.

In addition, the induction heating cooker of the present invention is particularly suitable for detecting boiling over, with the maximum value (ΔV: 12 digits) of the first change range (CL1) being equal to the threshold value (maximum value: 15 digits) of the third change amount (ΔV3). Alternatively, a configuration may be adopted in which it is difficult for erroneous detection to occur with a single shift with respect to erroneous detection such as pan shift by setting to be small.

In addition, in the induction heating cooker of the present invention, in particular, when the boiling detection unit satisfies the condition of the first predetermined time within the first change range, the timer count is set for a predetermined time (for example, a maximum count time of 60 seconds). continue. Meanwhile, the time when the timer count is started is stored as the reference value (Vo) of the capacitance, and the overflow detection is executed based on the amount of change from the reference value. At this time, the timer counts up to a predetermined time (for example, a maximum count time of 60 seconds), but at the end of the count, the timer is cleared and the update of the storage reference value is allowed to suppress the frequency of erroneous detection of spillover. be able to.

Furthermore, the induction heating cooker of the present invention, particularly when the spillover detection unit approaches the stored reference value, the timer is cleared and the reference value is updated, thereby generating erroneous detection of spillage. The frequency can be reduced.

According to the present invention, it is possible to improve the accuracy of detecting spillage without momentum, and it is possible to reliably detect regardless of the type of pan, the cooking menu, and the thermal power. In addition, even with a small amount of change, by using two-stage detection, the frequency of erroneous detection of spilling can be suppressed, and the occurrence of spilling can be reliably detected, and highly reliable induction heating is possible. A cooker can be provided.

It is possible to provide the market with a highly reliable induction heating cooker that can improve the accuracy of detection of spillage in the heating container that occurs during the induction heating operation, and can greatly reduce false detections.

DESCRIPTION OF SYMBOLS 1 Heating container 2 Top plate 4 Inverter 8 Control part 9 Electrode 10 Capacitance detection part 11 Overflow detection part 12 Memory | storage part 13 High frequency signal generator 14 Rectification part 15 Voltage detection part 18 Operation part 20 Display part

Claims

A top plate on which the heating container is placed;
A heating coil provided below the top plate for inductively heating the heating container;
An inverter for supplying a high frequency current to the heating coil;
An electrode provided on the back surface of the top plate in the vicinity of the periphery of the heating coil;
A capacitance detector for detecting a capacitance of the electrode by supplying a high-frequency current to the electrode;
A storage unit for storing a reference value for measuring the amount of change in the capacitance;
A control unit that controls the output of the inverter to be a first set value set by an output setting unit;
After the amount of change of the capacitance with respect to the reference value exceeds the fixed amount of spillage, the spillover detection is performed to stop the heating operation or reduce the output of the inverter to a second set value lower than the first set value. And comprising
The overflow detection unit replaces the capacitance detected during the predetermined period with the reference value when the state in which the change amount is less than the reference value update change amount smaller than the fixed overflow change amount continues for a predetermined period. Perform the reference value update process stored in the storage unit,
When the change amount is equal to or greater than the reference value update change amount, the overflow detection unit prohibits the reference value update process, and the timer starts counting and starts counting for a first predetermined time. If the change amount is continuously greater than or equal to the reference value update change amount and within the change range less than or equal to the determined overflow change amount or within a change range narrower than the change range, the preset time longer than the first predetermined time is set in advance Continue counting until the maximum count time has elapsed,
When the timer counts up to the maximum count time, the boiling detection unit is an induction heating cooker configured to restart the reference value update process.
The overflow detection unit stops heating after the second predetermined time has elapsed after the change amount is equal to or more than the determined overflow amount, or the output of the inverter is lower than the first set value. The induction heating cooker of Claim 1 comprised so that it might set to a 2nd setting value.
The said overflow detection unit is configured to restart the reference value update process when the change amount becomes less than the reference value update change amount after prohibiting the reference value update process. Induction heating cooker.