HK1181243B - Induction cooking device - Google Patents

Description

Induction heating cooker

Technical Field

The present invention relates to an induction heating cooker, and more particularly to an induction heating cooker having a function of detecting scorching in a heating container such as a pot during heating cooking.

Background

Conventionally, such an induction heating cooker performs a boiling detection operation after the start of heating, measures the viscosity and volume of a cooking material present inside a cooking container (for example, a pot) based on the temperature and input power at the time of boiling detection and a temperature change pattern until the end of boiling, and determines a stewing power required for heating after boiling. A conventional induction heating cooker is configured to have a stewing cooking mode in which when the soup in a heated cooking container is dried and the temperature of the bottom surface (pan bottom) of the cooking container rapidly rises and rises above a predetermined value, it is determined that the cooked object is burnt on the pan bottom (see, for example, patent document 1).

Fig. 14 is a block diagram of a conventional induction heating cooker, and fig. 15 is a flowchart showing an operation of the conventional induction heating cooker shown in fig. 14.

In fig. 14, a top plate 102 is a plate made of crystalline ceramic provided on the upper surface of the induction heating cooker, and a heating coil 103 is provided below the top plate 102. When a pan 101 as a cooking container is heated, the pan 101 is placed on the top plate 102 so that the bottom of the pan faces the heating coil 103. The inverter circuit 108a includes switching elements and resonant capacitors, constitutes an inverter together with the heating coil 103, and supplies a high-frequency current to the heating coil 103. The control unit 107 controls the on/off of the switching elements of the inverter circuit 108a to control the heating output. In order to detect the temperature of the pot 101 as a cooking container, a thermistor 104 is provided on the back surface of the top plate 102 on which the pot 101 is placed, and the temperature of the back surface of the top plate 102 is measured. The thermistor 104 outputs a detection signal obtained by measuring the temperature of the back surface of the top plate 102 to the control unit 107. The operation unit 110 operated by the user is provided with an output setting unit 110a, a heating start key 110b for starting a heating operation, and a control mode selection key 110c for selecting an operation mode. The output setting unit 110a includes: a down key 110aa for reducing the output set value by 1 st step every time it is pressed in the operation in the heating mode; and a raise key 110ab that increases the output setting value by 1 st step each time it is pressed.

Next, the operation of the conventional induction heating cooker configured as described above will be described with reference to fig. 15. When the power switch 106 is turned on (S301), the control unit 107 enters a standby mode. The control unit 107 stops the heating operation in the standby mode, and operates the control mode selection key 110c of the operation unit 110 to enable selection of one operation mode from among a plurality of operation modes including the stewing mode. When the operation mode is selected in the standby mode (S302) and the heating start key 110b is pressed (S303), the heating operation is started in the selected operation mode. For example, when the boiling mode is selected and the heating operation is started (yes in S304), the control unit 107 prohibits the output setting unit 110a from changing the output setting value, and automatically controls the heating output after the boiling detection operation is performed, as described in patent document 1. If an abnormal rise in the temperature of the pan 101 is detected based on the detection signal from the thermistor 104, the burnt coke detection function of the burnt coke detection section 105 that detects burnt coke is operated (S306). When, for example, the heating mode is selected instead of the stewing mode and the heating operation is started (S304: no), the control section 107 prohibits the scorch detection function from being operated (S305). At this time, the output set value in the output setting unit 110a can be changed.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 10-149875

Disclosure of Invention

Problems to be solved by the invention

However, in the conventional induction heating cooker configured as described above, the cooking mode in which the scorch detection function operates is limited to the simmering mode, and the output setting unit 110a is prohibited from changing the output setting value in the simmering mode. That is, in the heating mode in which the user can change the output set value in the output setting unit 110a, the user cannot operate the scorch detection function. Therefore, in order for the user to operate the scorch detection function in the induction heating cooker, the stewing mode must be selected. In the case of the stewing mode, if scorching does not occur at the temperature of the cooking container under stewing, there is no sharp temperature rise, and if a sharp temperature rise occurs, scorching may occur. Therefore, in the case of the stewing mode, a sharp temperature rise is detected, and scorching detection can be performed. However, in the other operation mode (heating mode), depending on the type of heating cooking, there is a case where the temperature of the pot 101 does not change constantly, but rapidly becomes high, and therefore it is difficult to detect the scorch accurately.

The present invention solves the problems of the conventional induction heating cooker configured as described above, and an object thereof is to provide an induction heating cooker including: in this induction heating cooker, even if cooking is performed in a heating mode in which a heating output can be freely selected by a user's operation, the scorch detection function can be activated when it is determined that the scorch detection function needs to be executed, and the scorch detection function can be deactivated when the scorch detection function performs an unnecessary operation and may have an adverse effect on the cooking operation. That is, an object of the present invention is to provide an induction heating cooker with good usability, which suppresses adverse effects on a normal cooking operation performed in a heating mode and prevents deterioration of a scorched degree.

Means for solving the problems

The induction heating cooker of the present invention solves the above problems in the conventional induction heating cooker, and includes: a top plate on which a cooking container is placed; an inverter circuit provided below the top plate and including a heating coil for heating the cooking container; an infrared sensor disposed below the top plate, detecting infrared rays emitted from a bottom surface of the cooking container and transmitted through the top plate, and outputting infrared detection information corresponding to a temperature of the bottom surface of the cooking container; a scorch detection unit for performing a scorch detection operation for detecting scorch of the cooking object on the bottom surface of the cooking container based on the infrared sensor information, and outputting scorch information; an output setting unit for selecting 1 output setting value from a plurality of different output setting values; and a control unit that controls a heating operation of the inverter circuit so that a high-frequency current is supplied to the heating coil and a heating output is set to a selected output set value, the control unit including: a 1 st timer for counting a measured cooking time from a start of a heating operation of the inverter circuit; and a load input detection unit for detecting that a load is input to the cooking container based on the infrared detection information output from the infrared sensor, wherein when the measured cooking time measured by the 1 st time measurement unit has not elapsed for a set time period of 1 st, the heating operation is continued even if the scorch detection information is output from the scorch detection unit, and when the load input detection unit detects that a load is input, the time measured by the 1 st time measurement unit is reset to restart the time measurement.

The induction heating cooker of the present invention configured as described above is capable of preventing the burnt state from becoming serious when cooking is performed in the heating mode in which heating is performed based on the heating output selected by the user, and avoiding the burnt state detection function from being activated to unnecessarily stop heating or reduce the heating output when cooking is performed in which the heating operation such as water boiling or cooking is completed in a short time, or in cooking such as grill cooking or barbecuing in which food material is additionally put during cooking and a required time for stirring or turning over the cooked material is performed. Thus, in the induction heating cooker of the present invention, the user can continue cooking without feeling awkward and without impairing usability.

In the means for solving the problems of the present invention described below, specific names of components, signal names, and the like in the embodiments described below are shown in parentheses to show the relevance, but the present invention is not limited to the description of the embodiments.

An induction heating cooker according to claim 1 of the present invention includes:

a top plate (1) on which a cooking container (2) is placed;

an inverter circuit (8) which is provided below the top plate and includes a heating coil (3) that heats the cooking container;

an infrared sensor (4) which is disposed below the top plate, detects infrared rays emitted from the bottom surface of the cooking container and transmitted through the top plate, and outputs infrared detection information (A) corresponding to the temperature of the bottom surface of the cooking container;

a scorch detection unit (50) for performing a scorch detection operation for detecting scorch of the cooking object on the bottom surface of the cooking container based on the infrared sensor information (A), and outputting scorch information (B);

an output setting unit (14) for selecting 1 output setting value from a plurality of different output setting values; and

a control unit (15) for controlling the heating operation of the inverter circuit so that the heating coil is supplied with a high-frequency current and the heating output is set to a selected output set value,

the control unit (15) includes: a 1 st timer unit (31) for counting a measured cooking time (Tp) from the start of a heating operation of the inverter circuit; and a load application detection unit (33) that detects that a load is applied to the cooking container (2) based on the infrared detection information (A) output from the infrared sensor (4),

when the measured cooking time (Tp) measured by the 1 st timer unit has not elapsed for the 1 st set time (T1), the heating operation is continued even if the scorch detection information (B) is output from the scorch detection unit, and when the load application detection unit detects that the load is applied, the time (Tp) measured by the first timer unit is reset to restart the measurement.

The induction heating cooker of claim 1 thus configured can discriminate between simmering and other cooking (for example, cooking) in the heating mode, detect scorching without deteriorating the scorching state in the case of simmering, and avoid unnecessary detection of scorching in cooking finished in a shorter time than in simmering, or in cooking or broiling in which a cooking object is mixed or turned over, thereby improving usability.

In an induction heating cooker according to claim 2 of the present invention, the load application detector (33) according to claim 1 is configured to: when the state in which the infrared detection information (A) output from the infrared sensor (4) has decreased by a predetermined value or more continues for a predetermined time, it is determined that the load has been applied. The induction heating cooker of claim 2 thus configured is capable of improving usability because unnecessary scorching detection is not performed in cooking or the like such as cooking of a mixed cooking material, in which the change in the infrared detection information (a) detected by the infrared sensor (4) is large.

In an induction heating cooker according to claim 3 of the present invention, the load application detector (33) according to claim 1 is configured to: when the infrared detection information (A) detected by the infrared sensor (4) does not rise for a predetermined time or more, it is determined that the load is applied. In the induction heating cooker of claim 3 thus constituted, unnecessary scorching detection is not performed in the case of barbeque cooking or the like in which the infrared detection information (a) detected by the infrared sensor (4) is unlikely to rise, such as turning the cooked item, and therefore usability can be improved.

In an induction heating cooker according to claim 4 of the present invention, the control unit according to claim 1 or 2 is configured to: when the measured cooking time (Tp) of the 1 st timer unit is equal to or less than a first elapsed set time (T1), and the scorch detection unit (50) outputs the scorch detection information (B), the temperature control is performed by controlling the heating operation of the inverter circuit so that the infrared detection information (A) becomes a value close to a predetermined set value within a range not exceeding the predetermined set value, and the reference for detecting the load application by the load application detection unit (33) is increased as compared with the case where the temperature control is not performed. The induction heating cooker of claim 4 thus configured can greatly suppress the progress of scorching even if the occurrence of scorching starts without performing unnecessary detection of scorching during, for example, cooking that has ended in a short time, and can avoid a situation in which the detection of scorching is not normally performed because the detection of load application is frequently performed.

In an induction heating cooker according to claim 5 of the present invention, the induction heating cooker includes: when the load application detection unit (33) detects that a load is applied after the measured cooking time of the 1 st timer unit (31) of any one of the 1 st to 4 th aspects exceeds the 1 st set time, the measured cooking time of the 1 st timer unit (31) is reset and the timer is restarted. The induction heating cooker of claim 5 thus constituted can improve usability because the detection of scorching does not unnecessarily operate even in the case of cooking or broiling cooking, such as mixing or turning of cooked items, which requires a long time or continuous cooking.

Effects of the invention

In the induction heating cooker of the present invention, even if the user can select the heating output and select the heating mode for performing the heating cooking different from the stewing mode to perform the stewing cooking, the user can detect the burnt paste and automatically stop the heating operation, or reduce the heating output and operate the heating mode without deteriorating the burnt paste state, and when the cooking such as the frying cooking is finished in a short time or the cooking such as the mixing or turning of the cooked objects is performed, the burnt paste detection function is not unnecessarily operated, thereby improving the usability.

Drawings

Fig. 1 is a block diagram showing an overall configuration of an induction heating cooker according to embodiment 1 of the present invention.

Fig. 2 is a circuit diagram showing a schematic configuration of an infrared sensor used in the induction heating cooker of embodiment 1.

Fig. 3 is a graph showing output characteristics of an infrared sensor in an induction heating cooker according to embodiment 1.

Fig. 4 is a diagram showing a relationship between a temperature detected by the infrared sensor and an elapsed time after the start of heating in the induction heating cooker according to embodiment 1.

Fig. 5 (a) and (b) are diagrams showing the relationship between the detected temperature of the infrared sensor and the elapsed time after the start of heating in the induction heating cooker of embodiment 1, and the relationship between the output power value W and the elapsed time.

Fig. 6 (a) and (b) are diagrams showing the relationship between the detection temperature of the infrared sensor and the elapsed time after the start of heating and the relationship between the output power value W and the elapsed time in the induction heating cooker of embodiment 1 for load application detection.

Fig. 7 is a flowchart showing a load drop detection operation when the temperature of the induction heating cooker of embodiment 1 drops.

Fig. 8 is a flowchart showing a load drop detection operation when the temperature of the induction heating cooker of embodiment 1 does not rise.

Fig. 9 (a), (b), and (c) are graphs showing the relationship between the detected temperature of the infrared sensor and the elapsed time after the start of heating in the induction heating cooker according to embodiment 2 of the present invention, the relationship between the output power value and the elapsed time, and the relationship between the predetermined temperature for detecting the load drop and the elapsed time.

Fig. 10 (a) and (b) are graphs showing the relationship between the detected temperature of the infrared sensor and the elapsed time after the start of heating in the induction heating cooker of embodiment 3, and the relationship between the output power value and the elapsed time.

Fig. 11 is a block diagram showing the overall configuration of an induction heating cooker according to embodiment 4 of the present invention.

Fig. 12 is a graph showing the rising time measuring operation and the falling temperature calculating operation of the scorched particles detecting unit in the induction heating cooker of embodiment 4.

Fig. 13A is a graph showing the relationship between determination values of the scorch detection operation of the scorch detecting unit in the induction heating cooker of embodiment 4.

Fig. 13B is another graph showing the relationship between determination values of the scorch detection operation of the scorch detecting unit in the induction heating cooker of embodiment 4.

Fig. 14 is a block diagram showing a structure of a conventional induction heating cooker.

Fig. 15 is a flowchart showing the operation of the conventional induction heating cooker.

Detailed Description

Hereinafter, an induction heating cooker according to an embodiment of the present invention will be described with reference to the drawings. The present invention is not limited to the specific configurations described in the following embodiments, and includes configurations based on the same technical ideas as those described in the embodiments and technical common knowledge in the technical field.

(embodiment mode 1)

Fig. 1 is a block diagram showing an overall configuration of an induction heating cooker according to embodiment 1 of the present invention. As shown in fig. 1, an induction heating cooker according to embodiment 1 includes: a ceramic top plate 1 provided on an upper surface of the induction heating cooker; and a heating coil 3 (an outer coil 3a and an inner coil 3 b) that inductively heats the cooking container 2 on the top plate 1 by generating a high-frequency magnetic field. The top plate 1 is made of an electrically insulating material such as glass, and is transparent to infrared rays. A heating coil 3 as an induction heating coil is disposed below the top plate 1. The heating coil 3 is divided into two concentrically and includes an outer coil 3a and an inner coil 3 b. A gap is formed between the inside of the outer coil 3a and the outside of the inner coil 3 b. The cooking container 2 placed on the top plate 1 generates heat by eddy current generated by the high-frequency magnetic field of the heating coil 3.

An operation unit 14 for a user to perform various operations such as start/stop of a heating operation and setting is provided in a region on the user side of the top panel 1. A display unit (not shown) is provided between the operation unit 14 and the region where the cooking container 2 is placed.

In the induction heating cooker of embodiment 1, the infrared sensor 4 as a cooking container temperature detector is provided below the gap between the outer coil 3a and the inner coil 3 b. In the induction heating cooker of the present invention, the position where the infrared sensor 4 is provided is not limited to the configuration of embodiment 1, and may be any position where the temperature of the cooking container 2 can be accurately detected. Infrared rays emitted from the bottom surface of the cooking container 2 based on the temperature of the bottom surface of the cooking container 2 pass through the top plate 1, pass through the gap between the outer coil 3a and the inner coil 3b, enter the infrared sensor 4, and are received by the infrared sensor 4. The infrared sensor 4 detects the received infrared rays and outputs an infrared detection signal a as infrared detection information based on the amount of infrared rays detected.

Below the heating coil 3 are provided: a rectifying/smoothing unit 7 that converts an ac voltage supplied from the commercial power supply 6 into a dc voltage; and an inverter circuit 8 that generates a high-frequency current by obtaining a dc voltage from the rectifying/smoothing unit 7 and outputs the generated high-frequency current to the heating coil 3. Further, an input current detection unit 9 (CT) for detecting an input current flowing from the commercial power supply 6 to the rectifying and smoothing unit 7 is provided between the commercial power supply 6 and the rectifying and smoothing unit 7.

The rectifying and smoothing unit 7 includes: a full-wave rectifier 10 constituted by bridge diodes; and a low-pass filter connected between output terminals of the full-wave rectifier 10 and composed of a choke coil 16 and a smoothing capacitor 17. The inverter circuit 8 includes: a switching element 11 (IGBT is used in embodiment 1); a diode 12 connected in anti-parallel with the switching element 11; and a resonance capacitor 13 connected in parallel with the heating coil 3. The switching element 11 of the inverter circuit 8 generates a high-frequency current by performing an on/off operation. The inverter circuit 8 and the heating coil 3 constitute a high-frequency inverter.

The induction heating cooker according to embodiment 1 further includes a control unit 15, and the control unit 15 controls the high-frequency current supplied from the inverter circuit 8 to the heating coil 3 by controlling the on/off operation of the switching element 11 of the inverter circuit 8. The control unit 15 controls the high-frequency current of the heating coil 3 based on an operation mode setting signal and a heating condition setting signal from the operation unit 14, and an infrared detection signal a detected by the infrared sensor 4, and controls the amount of heating power of the cooking container 2.

The control unit 15 includes: an inverter control unit 40 that controls on/off operations of the switching elements 11 based on an operation mode setting signal, a heating condition setting signal, and an infrared detection signal a (e.g., a voltage signal) from the infrared sensor 4, which are transmitted from the operation unit 14; a detected temperature calculation unit 30 that converts the infrared detection signal a of the infrared sensor 4 into a temperature and outputs a detected temperature signal; a 1 st timer 31 for counting a cooking time from the start of heating; and a load application detector 33 for detecting that a load is applied to the cooking container 2 based on a change in the detected temperature converted by the detected temperature calculator 30.

Here, in embodiment 1 of the present invention, the change in the detected temperature converted by the detected temperature calculating unit 30 is used, but the present invention is not limited to this, and the following configuration is also possible: in this configuration, the load application is detected directly by the load application detector 33 without performing temperature conversion based on the infrared detection signal a of the infrared sensor 4.

Further, the induction heating cooker of embodiment 1 is provided with a scorch detection unit 50. The measured cooking time signal measured by the 1 st timer 31 of the controller 15 and the detected temperature signal generated by the detected temperature calculator 30 are input to the scorch detector 50, and it is determined whether the cooking object is stew or another cooking (for example, cooking such as stir-frying) based on the measured cooking time signal and the detected temperature signal. If the scorch detecting part 50 determines to stew cooking and detects scorching at the bottom of the cooking container 2, the scorch detecting part 50 outputs a scorch detection signal B to the inverter control part 40 of the control part 15.

As described above, the operation unit 14 is provided in the region near the top plate 1 (user side), and the display unit for displaying the operation mode, the operation state, and the like is provided in the region between the operation unit 14 of the top plate 1 and the cooking container 2 placed thereon. The operation unit 14 includes a plurality of capacitive switches 14a to 14 c. The switches 14a to 14c are switches for inputting instructions related to cooking, and are provided in accordance with the number of heating coils 3. The switch of the operation unit 14 according to the present invention is not limited to the capacitance type, and various switching means such as a button type like a touch switch may be used.

Each of the switches 14a to 14c is assigned a specific function. For example, the switch 14a is an "off/on" switch to which a function of controlling the start and end of cooking is assigned. The operation unit 14 for inputting control commands such as heating conditions by user operation is provided with an output setting unit 14b and an operation mode selection key 14c for selecting an operation mode. A down key 14b2 for decreasing the output set value by 1 st gear and a up key 14b1 for increasing the output set value by 1 st gear are provided in the output setting portion 14 b. By performing key operations of the output setting unit 14b, one output setting value can be selected and set from a plurality of output setting values (for example, 6 steps of 1=100W, 2=300W, 3=700W, 4=1000W, 5=2000W, and 6= 3000W).

When it is detected that the switches 14a to 14c of the operation unit 14 are pressed, the inverter control unit 40 of the control unit 15 controls the driving of the inverter circuit 8 based on the pressed switches, and controls the high-frequency current supplied to the heating coil 3.

First, when the "off/on" switch 14a is pressed, the operation mode of the control unit 15 becomes a standby mode in which heating is stopped. In the standby mode, an operation mode for controlling an operation during the heating operation can be selected. In the standby mode, by operating the operation mode selection key 14c, one operation mode (heating mode, stewing mode, etc.) can be selected from a plurality of operation modes.

In the standby mode, when the heating mode is selected and the heating start key 14a is pressed (selected), the heating operation is started, and the control unit 15 automatically sets the output setting value to "set 4= 1000W" and shifts to the heating mode. Here, the heating mode is an operation mode in which heating is performed in accordance with an output set value selected by a user. The output setting portion 14b has a raise key 14b1 and a lower key 14b2, and when the control portion 15 operates in the heating mode, the output setting value can be changed to a desired setting (setting 1 to setting 6) by operating the output setting portion 14 b. When the output setting value is changed in the output setting unit 14b, the output setting unit 14b outputs an output setting signal indicating that the output setting value is changed to the control unit 15. The control unit 15 monitors the input current of the inverter circuit 8 in the input current detection unit 9 including a current transformer, and drives and controls the switching elements 11 constituting the inverter circuit 8 so that the heating output (infrared detection signal a) from the inverter circuit 8 becomes an output set value. Thus, the desired high-frequency current is supplied to the heating coil 3 by driving and controlling the switching element 11.

Fig. 2 is a circuit diagram showing a schematic configuration of an infrared sensor 4 as a cooking container temperature detector used in the induction heating cooker of embodiment 1. As shown in fig. 2, the infrared sensor 4 includes a photodiode 21, an operational amplifier 22, and 2 resistors 23 and 24. One end of the resistors 23, 24 is connected to the photodiode 21. The other end of the resistor 23 is connected to the output terminal of the operational amplifier 22, and the other end of the resistor 24 is connected to the inverting output terminal (-) of the operational amplifier 22. The photodiode 21 is a light receiving element formed of InGaAs or the like, and a current flows when infrared rays having a wavelength of about 3 μm or less transmitted through the top plate 1 are irradiated, and the magnitude and the increase rate of the current flowing increase as the temperature of the irradiated infrared rays increases. The current generated by the photodiode 21 is amplified by the operational amplifier 22, and is output to the control unit 15 as an infrared detection signal a (corresponding to a voltage value V0) indicating the temperature of the cooking container 2. Since the infrared sensor 4 used in the induction heating cooker of embodiment 1 is configured to receive infrared rays emitted from the cooking container 2, it has excellent thermal responsiveness compared to a thermistor that detects temperature through the top plate 1, and can realize high-precision control.

Fig. 3 is a graph showing the output characteristics of the infrared sensor 4. In fig. 3, the horizontal axis represents the bottom surface temperature (bottom temperature) of cooking container 2 such as a pan, and the vertical axis represents the voltage value (V0) of infrared detection signal a output from infrared sensor 4. When infrared rays having a wavelength of about 3 μm or less transmitted through the top plate 1 are irradiated to the photodiode 21 of the infrared sensor 4, a current flows through the photodiode 21. Since the photodiode 21 is a light receiving element formed of InGaAs or the like in which the magnitude and the increasing rate of the current flowing increases as the temperature of the infrared light to be irradiated increases, the infrared sensor 4 is switched as follows, for example, when 120 ℃ or higher and lower than 200 ℃ is defined as a low temperature region, 200 ℃ or higher and lower than 250 ℃ is defined as an intermediate temperature region, and 250 ℃ or higher and lower than 330 ℃ is defined as a high temperature region: as the temperature (detection value) of the irradiated infrared ray becomes higher, the magnification is switched, and the temperature region is switched as shown by low temperature region → medium temperature region → high temperature region.

In the induction heating cooker of embodiment 1, the infrared sensor 4 is switched as follows: outputting an infrared ray detection signal AL when the bottom surface temperature of the cooking container 2 is about 120 or more and less than 200 ℃; outputting an infrared detection signal AM when the bottom surface temperature is about 200 ℃ or higher and lower than 250 ℃; the infrared detection signal AH is output when the bottom surface temperature is about 250 ℃ or higher and less than 330 ℃. The infrared sensor 4 is configured not to output the infrared detection signal a when the bottom surface temperature of the cooking container 2 is lower than about 120 ℃. The "no infrared detection signal a" in this case includes not only a state in which the infrared sensor 4 does not output the infrared detection signal a at all, but also a state in which the infrared detection signal a is not substantially output, that is, a state in which the output control unit 15 cannot substantially read a weak signal of a degree of temperature change of the bottom surface of the cooking container 2 in accordance with a change in magnitude of the infrared detection signal a. The output value of the infrared ray detection signal a increases exponentially when the temperature of the cooking container 2 is about 120 ℃.

The temperature sensor of the infrared sensor 4 is not limited to a photodiode, and may include a temperature sensor such as a thermopile.

Next, the structure of the scorch detection unit 50 and the scorch detection operation in the induction heating cooker of embodiment 1 will be described with reference to fig. 4, 5, and 6. Fig. 4 is a graph showing the detected temperature Tn by way of example in order to explain a method for determining which of simmering cooking or other cooking (e.g., stir-frying cooking). Fig. 4 shows an example of the relationship between the detected temperature Tn of the infrared sensor 4 after the start of heating and the elapsed time. Fig. 5 (a) is a graph showing an example of the relationship between the detection temperature Tn [ ° c ] of the infrared sensor and the elapsed time [ sec ] after the start of heating, and fig. 5 (b) is a graph showing an example of the relationship between the output power value [ W ] and the elapsed time [ sec ]. Fig. 6 is an example of a case where the load application is detected during heating, fig. 6 (a) is a graph showing an example of a relationship between a detected temperature Tn [ ° c ] of the infrared sensor and an elapsed time [ sec ] after the start of heating, and fig. 6 (b) is a graph showing an example of a relationship between an output power value [ W ] and an elapsed time [ sec ].

Hereinafter, for simplicity of explanation, it is assumed that the output is set to "set 4= 1000W", and the actual output power value [ W ] is also 1000W without change. The control unit 15 receives the output voltage [ V0] of the infrared sensor 4, measures the magnitude of the output voltage [ V0], and transmits the information to the scorch detection unit 50. The infrared detection signal a from the infrared sensor 4 may be directly input to the scorch detection unit 50 without passing through the control unit 15. The scorch detector 50 includes a temperature storage unit (not shown) for storing the 1 st output voltage value V1 and the 2 nd output voltage value V2 larger than the 1 st output voltage value V1 in advance.

In fig. 4, the value indicated by the celsius degree is a value converted by the detected temperature calculating unit 30, and for example, the detected temperature Tn of the cooking container 2 is "Temp 1 (1 st set temperature)" [ ° c ] and indicates the temperature (for example, about 130 ℃) at which the 1 st output voltage value V1 is outputted from the infrared sensor 4.

Similarly, the detected temperature Tn of the cooking container 2 is "Temp 2 (2 nd set temperature)" [ ° c ] and represents a temperature (for example, about 240 ℃) when the 2 nd output voltage value V2 is output from the infrared ray sensor 4. Then, the output voltage from the infrared sensor 4 is converted into a temperature, and the temperature is expressed as a temperature Tn detected by the infrared sensor 4 in degrees celsius.

In fig. 4, when the temperature of the bottom surface of the cooking container 2 heated at the setting 4 (1000W) rises, the temperature detected by the infrared sensor 4 also starts to rise. Then, first, it is determined whether the cooking is a simmering cooking or another cooking (for example, a stir-frying cooking) based on the detected temperature Tn at which the measured cooking time Tp from the start of heating measured by the 1 st timer unit 31 reaches the preset initial elapsed setting time T0. In the case of stew cooking, since the water content is high as compared with other cooking, the temperature of the cooking material in the cooking container 2 generally changes around 100 ℃, and when the water content evaporates and disappears and the cooking material starts to be burnt, the temperature of the cooking container 2 also starts to rise. On the other hand, in the case other than the cooking, the temperature generally continuously rises while the heating is continued. The cooking object is discriminated on the basis of the difference. If the detected temperature Tn when the measured cooking time Tp reaches the initial elapsed set time T0 is higher than the 1 st set temperature Temp1[ deg.C ], it is judged as cooking other than simmering cooking, such as cook-fry cooking, in which the water content is small, and if the detected temperature Tn at this time is the 1 st set temperature Temp1[ deg.C ] or less, it is judged as simmering cooking.

Next, as shown in fig. 5, after it is determined that the cooking is simmering because the detected temperature Tn at which the measured cooking time Tp from the start of heating reaches the initial elapsed setting time T0 is the 1 st setting temperature Temp1 or less, if the heating is continued, the moisture content of the cooked material gradually decreases. Finally, the water content of the cooked product disappears and scorching starts to occur. Since the detected temperature Tn starts to rise as the scorch progresses, when the detected temperature Tn reaches the 2 nd set temperature Temp2[ ° c ], the scorch detection unit 50 determines that scorch has occurred during the cooking of the food, and outputs a scorch detection signal B.

At this time, it is originally desired that the control unit 15 drive-controls the inverter circuit 8 to stop the heating operation of the heating coil 3 with respect to the cooking container 2, but, for example, even in the case of cooking, depending on the type or amount of the cooking object, water seeps out from the cooking object during cooking, and even if heating is continued, the temperature is hardly raised, and in the case where the measured cooking time Tp reaches the initial elapsed setting time T0, the detected temperature Tn may become equal to or lower than the 1 st setting temperature Temp1 even in the case of cooking. In such a case, when cooking is continued, even if the cooking is done, it is determined that the cooking is scorched during stewing, and heating is stopped during cooking.

Therefore, in the induction heating cooker of embodiment 1, as shown in fig. 5 (B), for example, even if the scorch detection signal B is output from the scorch detection unit 50, the possibility of cooking is not zero, and therefore, the heating operation is continued for a certain time, and when the measured cooking time Tp from the start of heating reaches the 1 st elapsed set time T1 and the detected temperature Tn at that time is still equal to or higher than the 2 nd set temperature Temp2, the scorch detection unit 50 determines that the occurrence of scorch is detected, and stops the heating control of the control unit 15, and stops the heating operation of the cooking container 2. In this case, if the induction heating cooker is provided with a display unit or a notification unit, the induction heating cooker may be configured such that: the user is notified that the occurrence of scorch has been detected and the heating action is stopped.

In the induction heating cooker of embodiment 1, the reason why the heating operation is continuously performed until the set time T1 elapses from the 1 st time is that: generally, since the stew cooking often takes a long time, and the other cooking (for example, the cook cooking) is often completed in a shorter time than the stew cooking, the possibility of stopping the heating operation before the cooking is completed can be reduced by continuing the heating operation without erroneously judging the cook cooking or the like as the stew cooking.

As is clear from the above, the longer the 1 st elapsed setting time T1 is, the more the heating operation before completion of cooking in cooking other than the simmering cooking can be prevented from being stopped, but if the time is set to be too long, there is a problem as follows: when scorching occurs during actual cooking, the scorching expands. Therefore, it is desirable to set the time: this time is longer than the time assumed to be normally completed in cooking other than the simmering cooking, and is as short as possible.

However, if cooking is performed for a certain long period of time, such as when cooking is erroneously determined to be simmering and cooking is repeated, there is a possibility that heating may be erroneously stopped even if the above control is performed.

As shown in fig. 6 (a), when the detected temperature Tn exceeds the first set temperature Temp1, the temperature of the detected temperature Tn should be continuously increased as it is in the case of the scorch during the stewing cooking, but the temperature of the bottom surface of the cooking container 2 is changed and the detected temperature Tn is decreased in the case of the mixing of the cooked material or the turning over of the cooked material during the cooking, such as the stir-frying or the grill cooking. When the load application detection unit 33 determines that the temperature drop of the detected temperature Tn is a load application by a determination means described later, the timer for Tp is reset and the timer is restarted. In fig. 6 (a), originally, at Td1 when the elapsed time Tp from the start of heating reaches T1, the detected temperature Tn exceeds the second set temperature Temp2 and it should be determined that scorch is occurring, but since it is detected before that the load is applied, Tp is reset and re-timed, Tp does not reach the first elapsed set time T1 and it is not determined that scorch is occurring. Thereafter, at a time point when Tp, which is counted again from the time point when the load application is detected, exceeds 1 st elapsed setting time T1 and Tn is Td2 equal to or greater than Temp2, the scorch detector 50 determines that scorch is occurring during cooking, and outputs a scorch detection signal B.

Next, a method for determining the load drop in the load drop detector 33 in the induction heating cooker according to embodiment 1 will be described with reference to fig. 7 and 8. Fig. 7 and 8 are flowcharts each showing a load drop detection operation executed by the load drop detection unit 33 based on a temperature change in the detected temperature Tn detected by the detected temperature calculation unit 30.

In fig. 7, the detection temperature Tn is first detected (step s 1). Next, at step s2, it is determined whether or not the temperature Tn detected at step s1 is higher than the maximum temperature Tn (max) measured up to this point. In step s2, since the detected temperature Tn continues to rise when scorching has occurred during the cooking, Tn should be higher than Tn (max), and therefore step s2 is an important part for determining whether scorching has actually occurred during the cooking. If it is determined in step s2 that Tn is higher than Tn (max), the process proceeds to step s3, where Tn (max) is updated to Tn.

On the other hand, when it is determined in step s2 that Tn is not more than Tn (max), the process proceeds to step s 4. In step s4, it is determined whether the detection temperature Tn has dropped by a predetermined temperature (5 ℃ C. in the present embodiment) or more from Tn (max). That is, when the mixture of the cooked materials in the cooking or the like is performed, or when the additional addition of the food material is performed, or the like, a temperature drop is observed, and it is determined whether or not the temperature actually changes due to a factor other than the scorch in the cooking or the like. If the detection temperature Tn is judged to be 5 ℃ lower than Tn (max), the routine proceeds to step s 5.

Then, in step s5, it is determined whether or not the temperature decrease of 5 ℃ or more in step s4 continues for a predetermined time (5 seconds or more in the present embodiment). In the measurement of the detected temperature Tn, the temperature may be instantaneously lowered by external disturbance or the like, or even in the case of stew cooking, the temperature may be lowered for a very short time due to repetition of boiling and evaporation of water during scorching of the cooked product, and therefore, in order to accurately detect the load placed on the cooking container 2 without making a false determination with respect to such a phenomenon, the step s5 is required.

If it is determined in step s5 that the temperature decrease of 5 ℃ or more has continued for 5 seconds or more, it is confirmed that the load has been applied.

In fig. 8, unlike the flowchart of load placement detection shown in fig. 7, step s4 in fig. 7 is not present in fig. 8, the determination time at step s5 in fig. 7 is longer in fig. 8, and the rest of the description is omitted, similarly to fig. 7.

In step s2 of fig. 8, it is determined whether or not the detected temperature Tn detected in step s1 is higher than the highest temperature Tn (max) measured up to this point. When it is determined in step s2 that Tn is not more than Tn (max), the process proceeds to step s 5. In step s5, it is determined whether or not the state in which Tn is the highest temperature Tn (max) or less in step s2 continues for a predetermined time (20 seconds or more in the present embodiment). In step s5, for example, when cooking is performed by baking a pancake or a miscellaneous pancake, or when the cooking object is turned upside down after one surface is baked, a significant drop in temperature is not observed because a certain degree of heat is always maintained, but if the heating is not continued for a while, the temperature does not rise, and step s5 corresponds to such a case, and the 5 seconds set in fig. 7 should be set to a time longer than at least 5 seconds in the pattern of fig. 8.

If it is determined at step s5 that the state in which the temperature rise has not occurred continues for 20 seconds or longer, it is determined that the load has been applied.

Accordingly, according to the induction heating cooker of embodiment 1, it is determined whether the cooking is simmering or another cooking (for example, cooking), and when the temperature Tn measured in the simmering reaches the 2 nd set temperature Temp2, the scorch detection information (scorch detection signal B) is output, and when the measured cooking time Tp measured by the 1 st timer 31 reaches the 1 st elapsed set time T1 or more, the heating of the cooking container 2 by the heating coil 3 is stopped, and when the load application detector 33 determines that the load is applied, the measured cooking time Tp is reset and the time measurement is restarted, whereby the heating can be continued until the cooking is completed even when the cooking is performed by cooking or broiling and if the cooking is erroneously determined to be simmering.

In addition, in the induction heating cooker of embodiment 1, the detection temperature calculating unit 30 is configured to convert the output voltage of the infrared sensor 4 into the temperature, but the present invention is not limited to this configuration, and similar effects can be obtained even with a configuration in which the control is directly performed based on the output voltage of the infrared sensor 4.

In the induction heating cooker of embodiment 1, the output set value is set to 4 (1000W), but the present invention is not limited thereto, and the same control may be performed for other set values. Further, if the initial elapsed setting time T0, the 1 st elapsed setting time T1, and the 1 st set temperature Temp1 and the 2 nd set temperature Temp2, which are threshold values of the detected temperature Tn of the infrared sensor 4, are set to optimum values for each output setting value, more accurate control is possible.

Further, if the initial elapsed time T0, the 1 st elapsed time T1, and the 1 st set temperature Temp1 and the 2 nd set temperature Temp2, which are threshold values of the detected temperature Tn of the infrared sensor, are set to respective optimum values according to the type of the metal material of the cooking container 2 that can be determined based on information from the inverter circuit 8 (for example, information such as the on time of the switching element 11, the current flowing through the heating coil 3, the frequency of the control switching element 11, and the current supplied to the inverter circuit 8), it is possible to perform determination with higher accuracy. This is because not only the size of the cooking container 2 but also the difference in characteristics such as thermal conductivity and the like occur depending on the kind of the metal material, and the degree of progress of the scorch varies depending on the difference in thermal conductivity and the like.

In the induction heating cooker of embodiment 1, the output set value is not limited, but it is difficult to distinguish between the simmering cooking and cooking other than the simmering cooking (for example, cooking) based only on the detected temperature of the infrared sensor 4 as the heating power is higher, and therefore, it is desirable to make the scorching detection function of the simmering cooking function to be effective only when the output set value is equal to or lower than a predetermined value. The method can be realized by the following modes: the control unit 15 performs control so that the scorch detection function is disabled when the value set by the output setting unit 14b of the operation unit 14 is higher than a predetermined value.

In addition, although the induction heating cooker of embodiment 1 is configured to stop the heating operation after confirming that scorch is detected, the present invention is not limited to this configuration, and may be configured as long as it can suppress the development of scorch, and for example, may be configured as follows: the heating operation is continued with an output corresponding to the heating power at the time of so-called heat retention in which the heating output is about 100W to 200W.

In the induction heating cooker of embodiment 1, the condition for determining that scorch is detected is set to the case where the cooking time from the start of heating reaches the first elapsed time T1, but the present invention is not limited to this case, and for example, the condition for determining that scorch is detected may be set to the case where the integrated power from the start of heating reaches the predetermined value. Further, by changing the accumulated power according to the type of the metal material of the cooking container 2 that can be determined based on the information from the inverter circuit 8, the accuracy can be further improved. This is because various characteristics such as thermal conductivity vary depending on the kind of the metal material, and the degree of progress of the scorch varies depending on the difference in thermal conductivity, and this is another important factor, and the thermal efficiency of the power supplied from the inverter circuit 8 to the cooking container 2 varies depending on the kind of the metal material.

Further, according to the induction heating cooker of embodiment 1, since the bottom surface temperature of the cooking container 2 is detected by the infrared sensor 4, the bottom surface temperature can be detected with high responsiveness as compared with the case of using a temperature sensing element such as a thermistor, and therefore, the scorch can be detected with high accuracy.

Further, according to the induction heating cooker of embodiment 1, when the load application detection unit 33 detects that the load is applied, the measurement cooking time Tp is reset and newly measured, but the present invention is not limited thereto, and the following configuration may be adopted: when it is desired to control so as not to perform the scorch detection as much as possible, the scorch detection is not performed until the heating is continued after the load application is detected.

(embodiment mode 2)

Next, an induction heating cooker according to embodiment 2 of the present invention will be described with reference to fig. 1 to 4 and 9. Note that the same reference numerals are given to parts having the same functions and configurations as those described in the induction heating cooker of embodiment 1, and the description thereof is omitted.

Fig. 9 is a graph showing an example of the relationship between the detected temperature Tn [ ° c ] of the infrared sensor 4 and the elapsed time [ sec ] after the start of heating in the induction heating cooker according to embodiment 2 of the present invention (fig. 9 (a)), a graph showing an example of the relationship between the output power value [ W ] and the elapsed time [ sec ] (fig. 9 (b)), and a graph showing an example of the relationship between the predetermined value of temperature drop in load application and determination [ ° c ] and the elapsed time [ sec ] (fig. 9 (c)).

In fig. 9, when the detected temperature Tn reaches the 2 nd set temperature Temp2, the scorch detection unit 50 outputs a scorch detection signal B. However, since the measured cooking time Tp from the start of heating has not yet reached the 1 st set time T1, the heating control by the control unit 15 is not stopped. However, if the heating is continued while maintaining the output power value (1000W in embodiment 2), the temperature of the cooking container 2 continues to rise, and if scorching occurs during the stew cooking, the degree of scorching develops and continues to deteriorate.

To avoid this, in the induction heating cooker of embodiment 2, when the detected temperature Tn reaches the 2 nd set temperature Temp2, the heating operation is turned off. As a result, when the detected temperature Tn decreases and reaches the 3 rd set temperature Temp3 (in embodiment 2, the 3 rd set temperature Temp3 is set to a value 5 ℃ lower than the 2 nd set temperature Temp 2) which is lower than the 2 nd set temperature Temp2, the heating operation is again brought into the on state. That is, the temperature control is performed so that the detected temperature Tn does not exceed the 2 nd set temperature Temp 2. When the measured cooking time Tp from the start of heating reaches the 1 st set time T1 and the detected temperature Tn reaches the 2 nd set temperature Temp2, it is determined that scorching has occurred during the cooking, and the heating control by the controller 15 is stopped to stop the heating operation of the cooking container 2.

In the temperature regulation control described above, the detected temperature Tn may be lowered by a predetermined temperature or more for a predetermined time or more depending on variations in the material and size of the pot, the type and amount of the cooking material, and the like, and the load application detection unit 33 determines that a load is applied, clears the measured cooking time Tp, and does not operate the detection of the scorch while the cooking is in the scorch state.

To avoid this, in embodiment 2 of the present invention, when the detected temperature Tn reaches the second set temperature Temp2 and the temperature adjustment control is started, the enlarged load application detector 33 determines that the detected temperature at which the load is applied has decreased by a predetermined value. As shown in fig. 9 (c), the predetermined value is enlarged from 5 ℃ to 20 ℃ in the present embodiment.

As described above, in the induction heating cooker of embodiment 2, the scorch detection unit 50 of the control unit 15 determines whether the cooking is the simmering or another cooking (for example, a cooking), and when the temperature Tn reaches the 2 nd set temperature Temp2 during the simmering, performs the temperature adjustment control so that the detected temperature Tn does not exceed the 2 nd set temperature Temp2, outputs scorch detection information (scorch detection signal B), and the enlarged load drop detection unit 33 determines that the temperature at which the load is dropped has decreased by a predetermined value (that is, increases the reference for detecting the load drop). The induction heating cooker of embodiment 2 is configured to stop the heating operation of the heating coil 3 on the cooking container 2 when the measured cooking time Tp measured by the 1 st timer unit 31 reaches the 1 st elapsed set time T1 or more. Further, since the induction heating cooker of embodiment 2 is configured as described above, even when cooking is performed, if cooking is erroneously determined to be stew cooking, heating can be continued until cooking is completed, and development of scorching during stew cooking can be suppressed.

In addition, in the induction heating cooker of embodiment 2, the following actions are taken: after the measured cooking time Tp reaches the 1 st set time T1 and the detected temperature Tn reaches the 2 nd set temperature Temp2, it is determined that scorching is detected. However, for example, the following actions (e.g., an action to display the blur) may also be taken: since the temperature adjustment control is already performed after the detected temperature Tn reaches the 2 nd set temperature Temp2, it is determined that scorching is detected at the time when the measured cooking time Tp reaches the 1 st elapsed set time T1.

In the induction heating cooker of embodiment 2, after the detected temperature Tn reaches the 2 nd set temperature Temp2, the temperature adjustment control is performed so that the detected temperature Tn does not exceed the 2 nd set temperature Temp2 until the measured cooking time Tp from the start of heating reaches the 1 st set time T1. However, the present invention is not limited to this configuration, and similar effects can be obtained even with a configuration in which the output of the heating operation is changed in accordance with the slope or absolute value of the temperature change of the detected temperature Tn (for example, fuzzy control). Further, although the configuration in which the temperature adjustment control is performed based on the on/off control of the heating operation has been described, the temperature adjustment control may be performed, for example, by changing the heating output without turning the heating operation off.

(embodiment mode 3)

Next, an induction heating cooker according to embodiment 3 of the present invention will be described with reference to fig. 1 to 4 and 10. Note that the same reference numerals are given to parts having the same functions and configurations as those described in the induction heating cookers of embodiment 1 and embodiment 2, and the description thereof is omitted.

Fig. 10 is a graph showing an example of the relationship between the temperature Tn [ ° c ] detected by the infrared sensor 4 after the start of heating and the elapsed time [ sec ] (fig. 10 (a)), and a graph showing an example of the relationship between the output power value [ W ] and the elapsed time [ sec ] (fig. 10 (b)), in the induction heating cooker according to embodiment 3.

In the graph shown in fig. 10 (a), even if the initial elapsed set time T0 has elapsed since the start of heating, the temperature Tn detected by the infrared sensor 4 is equal to or lower than the 1 st set temperature Temp1, and therefore the scorch detector 50 determines that the cooking is performed at that time. Then, the heating operation is continued, and only when the measured cooking time Tp exceeds the 1 st set time T1 and the detected temperature Tn reaches the 2 nd set temperature Temp2, the scorch detection unit 50 outputs scorch detection information (scorch detection signal B), and the heating control of the control unit 15 is stopped, and the heating operation for the cooking container 2 is stopped.

When the load application detector 33 determines that the load such as the cooking material is applied after the measured cooking time Tp exceeds 1 st and the set time T1 elapses, the measured cooking time Tp is reset and the timer is restarted (at Td 4). Thereafter, when the measured cooking time Tp, which is newly started, exceeds the first elapsed setting time T1 and the detected temperature Tn reaches the second setting temperature Temp2, the scorch detection unit 50 outputs scorch detection information (scorch detection signal B), stops the heating control of the control unit 15, and stops the heating operation of the cooking container 2.

In the induction heating cooker of embodiment 3 configured as described above, the scorch detection unit 50 determines whether the cooking is simmering or another cooking (for example, cooking), and, when the load application detector 33 detects the application of the load after the measured cooking time Tp from the start of heating exceeds the set time T1 that has elapsed since the time T1 passed, the measurement of the measured cooking time Tp is restarted, and, even if cooking time is long when cooking time is determined to be stew cooking such as stir-fry cooking or grill cooking, the load input detector 33 can detect that the temperature is decreased due to the mixing of the cooking materials for cooking, the turning over of the cooking materials during the grill cooking, or the like, and by continuing the heating for the 1 st set time period, even if cooking or broiling cooking is being performed, if the cooking is erroneously determined to be stew cooking, it is possible to prevent a problem that the heating operation is stopped by determining that scorching has been detected before the cooking is completed.

In the induction heating cooker of embodiment 3, the heating is continued even after the detected temperature Tn reaches the 2 nd set temperature Temp 2. However, the present invention is not limited to this configuration, and the control unit 15 may be configured to execute the following temperature control: before the measured cooking time Tp reaches the 1 st elapsed set time T1, the detected temperature Tn is not allowed to exceed the second set temperature Temp 2.

(embodiment mode 4)

Next, an induction heating cooker according to embodiment 4 of the present invention will be described with reference to fig. 2 to 4, fig. 11 to 13A, and fig. 13B. Note that the same reference numerals are given to parts having the same functions and configurations as those described in the induction heating cookers of embodiment 1 and embodiment 2, and the description thereof is omitted.

Fig. 11 is a block diagram showing the overall configuration of an induction heating cooker according to embodiment 4 of the present invention. Fig. 12 is a graph showing an example of the rising time measuring operation and the falling temperature calculating operation of the scorch detection unit 50 in the induction heating cooker of embodiment 4. Fig. 13 is a graph for explaining the operation of detecting scorching by the scorching detector 50 in the induction heating cooker of embodiment 4, and shows an example of the determination value.

In the induction heating cooker of embodiment 4 shown in fig. 11, the scorch detection unit 50 includes: a rise time measuring unit 51 for measuring the rise time of the detection temperature Tn of the infrared sensor 4; a drop temperature calculation unit 52 that calculates a temperature drop of the detected temperature Tn within a predetermined time after the heating operation is stopped; a storage unit 53 that stores the values obtained by the rise time measurement unit 51 and the fall temperature calculation unit 52; and a determination unit 54 for calculating a determination value based on the values obtained by the rise time measurement unit 51 and the fall temperature calculation unit 52, and determining whether the cooking is stewing or other cooking based on the determination value. The control unit 15 includes a load application detection unit 33 in addition to the inverter control unit 40, the 1 st timer unit 31, and the detected temperature calculation unit 30, and the load application detection unit 33 detects that a load such as a cooking material is applied to the cooking container 2 based on a temperature change in the detected temperature Tn detected by the detected temperature calculation unit 30.

Hereinafter, a method of determining cooking by stew and other cooking in the induction heating cooker of embodiment 4 will be described with reference to fig. 12 and 13A.

In the detected temperature Tn shown in fig. 12, for example, when the temperature of the bottom surface of the cooking container 2 heated at the set temperature 4 (1000W) rises, the detected temperature Tn of the infrared sensor 4 starts rising, and the detected temperature Tn reaches the 1 st set temperature Temp1, but the measured cooking time Tp from the start of heating does not reach the initial elapsed set time T0, it cannot be determined as stew cooking. Therefore, the discrimination between the stew cooking and other cooking (for example, the cook cooking) is performed based on the temperature rise and the temperature fall of the detected temperature Tn. The discrimination method is described below.

First, the rise time measuring unit 51 measures the rise time Tup required for the detected temperature Tn to rise from the 1 st set temperature Temp1[ ° c ] to the 4 th set temperature Temp4[ ° c ]. The 4 th set temperature Temp4[ ° c ] is preferably equal to or lower than the 2 nd set temperature Temp2, which is a scorch detection temperature, or lower than the 2 nd set temperature Temp2, and is preferably set to 160 ℃ in embodiment 4. Then, the heating operation is stopped for a predetermined time T (for example, 10 seconds) from the detected temperature Tn reaching the 4 th set temperature Temp 4. The reduced temperature calculation unit 52 calculates a reduced temperature of the bottom surface temperature of the cooking container 2 within the predetermined time T after the heating operation is stopped. The calculation method may be simply calculated using a value indicating how much the detected temperature Tn after the elapse of the predetermined time T has decreased from the 4 th set temperature Temp4, or may be calculated using the reached temperature after the predetermined time has elapsed since the stop of heating, but the following method is executed in the induction heating cooker of embodiment 4: the temperature drop per second was measured, and the average value Tave of the temperature drop over a period of 10 seconds was calculated.

Next, the operation of the determination unit 54 in the scorch detection unit 50 will be described with reference to fig. 13. In fig. 13A, the vertical axis represents the rise time [ sec ] measured by the rise time measuring unit 51, and the horizontal axis represents the average value of the falling temperatures [ ° c ] calculated by the falling temperature calculating unit 52.

The determination reference value C of the average values of the rise time and the fall temperature shown in fig. 13A is previously determined in accordance with the specification of the induction heating cooker. As shown in fig. 13A, an area above the boundary line of the determination criterion C is defined as a stewing area, and an area below the boundary line of the determination criterion C is defined as a cooking area. In addition, the boundary line of the determination criterion C is defined as a stewing area. Here, there is a correlation between the degree of temperature drop at the time of heating stop and the thickness of the cooking container, and the greater the thickness of the cooking container, the greater the heat capacity, and therefore the slower the temperature drop. If the thickness of the cooking vessel can be practically ignored, the rise time is long in the case of stewing and short in the case of cooking. Thus, the cooking area and the cooking area can be discriminated using the predetermined rise time as a boundary.

However, it is actually necessary to consider the thickness of the cooking container, and as described above, the rise time becomes longer as the thickness of the cooking container becomes larger, even if the same cooking is performed. So that the greater the thickness of the cooking container, the more the rightward growth tendency of the boundary line of the cooking area and the cook area is inclined, as shown in fig. 13A.

After the rise time Tir measured by the rise time measuring unit 51 of the scorch detecting unit 50 and the fall temperature average value Tave calculated by the fall temperature calculating unit 52 are determined in the determining unit 54, as shown in fig. 13, it is determined whether the cooking is stewing cooking or other cooking (for example, cooking). When the rise time Tir from the rise time measuring unit 51 and the fall temperature average value Tave from the fall temperature calculating unit 52 are determined, the boundary line of the coordinates (Tir 1 and Tave 1) in fig. 13 with respect to the criterion C is located in the lower region, and therefore the result of the determination is regarded as cooking and heating is continued without detecting scorching.

On the other hand, when the rise time Tir from the rise time measuring unit 51 and the fall temperature average value Tave from the fall temperature calculating unit 52 are coordinates (Tir 2 and Tave 2), the boundary line with respect to the determination criterion C is located in the upper region, and thus the determination result is determined as stew cooking. When it is determined that the cooking is performed by the stewing operation, the detected temperature Tn reaches the 2 nd set temperature Temp2[ ° c ] and the measured cooking time Tp from the start of heating is equal to or longer than the 1 st elapsed set time T1, it is determined that the scorch is detected, the heating control by the controller 15 is stopped, and the heating operation of the cooking container 2 is stopped. When it is determined that the cooking is done by stewing, the load application detector 33 clears the measured cooking time Tp from the start of heating when it detects that the load is applied during heating, and restarts the timer.

In the induction heating cooker according to embodiment 4 configured as described above, the scorch detection unit 50 determines whether the cooking is simmering or another cooking (for example, cooking), and outputs scorch detection information (scorch detection signal B) when the temperature Tn reaches the 2 nd set temperature Temp2 during the simmering. Further, by stopping the heating operation of the heating coil 3 on the cooking container 2 when the measured cooking time Tp measured by the 1 st timer unit reaches the 1 st elapsed set time T1 or more, even if cooking is performed, and cooking is erroneously determined to be stew cooking, the heating operation can be continued until cooking is completed, and when the temperature of the bottom surface of the cooking container 2 heated at, for example, the setting 4 (1000W) rises and the temperature of the infrared sensor 4 starts to rise, the scorch detector 50 measures the rise time Tup from the 1 st set temperature Temp1[ ° c ] to the 4 th set temperature Temp4[ ° c ] by the rise time measurement unit 51, whereby cooking in a cooking system with a short rise time and cooking in a stew system with a long rise time can be determined. Then, the heating operation is stopped for a predetermined time T (for example, 10 seconds) from when the detected temperature Tn reaches the 4 th set temperature Temp4 (° C), and the falling temperature of the bottom surface temperature of the cooking container 2 is calculated by the falling temperature calculating unit 52 for each second (average value Tave of the falling temperatures during 10 seconds), for example, whereby the thickness of the bottom portion of the cooking container 2 to be used can be estimated so that the relationship between the rising time and the thickness of the bottom portion of the cooking container 2 estimated from the falling temperature becomes a linear proportional equation (boundary line of the determination reference C) shown in fig. 13, and the distinction between the cooking and the cooking can be determined with high accuracy.

In addition, a thickness range of a cooking container that is generally used may be considered, and as shown in fig. 13B, when the thickness is equal to or less than a certain thickness or when the thickness is equal to or more than a certain thickness, the boundary line of the determination value may be made a fixed value.

As shown in fig. 13A and 13B, the horizontal axis may be the arrival temperature after a predetermined time has elapsed. Similarly, the vertical axis may be an increase temperature per second in temperature increase.

In fig. 13A, the inclination of the boundary line of the determination value is not fixed, and the inclination is set in consideration of the fact that the material used differs depending on the thickness of the cooking container and the thermal conductivity differs. That is, generally, when the thickness is not more than a certain fixed thickness, the cooking container is almost made of stainless steel, and the thermal conductivity of stainless steel is small. Therefore, the rise time is larger, and therefore the inclination is set larger.

As described above, in the induction heating cooker of the present invention, even when cooking is performed in the heating mode in which the heating output can be freely selected by the user's operation, the scorch detection function can be activated when it is considered necessary to perform the scorch detection function, and the scorch detection function can be inhibited when the scorch detection function is unnecessarily activated and may adversely affect the cooking operation. Further, even when it is determined that the cooking is stew in the cooking, broiling, or the like, the load input detector 33 can detect that the temperature is lowered due to the mixing of the cooking materials for the cooking, the turning over of the cooking materials during the broiling, or the like, and continue the heating during the lapse of the set time of the 1 st time, thereby preventing the problem that the heating operation is stopped by the determination that the scorch is detected before the cooking is completed. Therefore, according to the present invention, it is possible to provide an induction heating cooker which is excellent in usability and which can suppress adverse effects in a normal cooking operation performed in a heating mode and can prevent deterioration of a scorched level.

Industrial applicability

The induction heating cooker of the present invention can detect scorching in an operation mode in which heating is performed based on an output setting selected by a user, and can continue cooking without unnecessarily performing scorching detection in cooking such as stir-fry cooking, and therefore, the induction heating cooker of the present invention can be widely applied to induction heating cookers of an embedded type, a tabletop type used on a table, a fixed type used on a mounting table, and the like in home use or business use.

Description of the reference symbols

1 Top plate

2 cooking vessel

3 heating coil (Induction heating coil)

4 infrared sensor

8 inverter circuit

14 operating part

15 control part

31 st timer part

33 load input detector

40 inverter control unit

50 burnt detecting part

51 rise time measuring unit

52 reduced temperature calculation unit

53 storage unit

54 judging unit

Claims (6)

1. An induction heating cooker, comprising:

a top plate on which a cooking container is placed;

an inverter circuit provided below the top plate and including a heating coil for heating the cooking container;

an infrared sensor disposed below the top plate, detecting infrared rays emitted from a bottom surface of the cooking container and transmitted through the top plate, and outputting infrared detection information corresponding to a temperature of the bottom surface of the cooking container;

a scorch detection unit for performing a scorch detection operation for detecting scorch of the cooking object on the bottom surface of the cooking container based on the infrared sensor information, and outputting scorch information;

an output setting unit for selecting 1 output setting value from a plurality of different output setting values; and

a control unit for controlling a heating operation of the inverter circuit so that a high-frequency current is supplied to the heating coil and a heating output is set to a selected output set value,

the control unit includes: a 1 st timer for counting a measured cooking time from a start of a heating operation of the inverter circuit; and a load application detection unit for detecting that a load is applied to the cooking container based on the infrared detection information output from the infrared sensor,

the induction heating cooker comprises:

when the cooking time measured by the 1 st timer unit has not elapsed for the set time 1, the heating operation is continued even if the burnt detection information is output from the burnt detection unit,

when the load application detection unit detects that the load is applied, the time counted by the 1 st timer unit is reset and the timer is restarted.

2. The induction heating cooker as claimed in claim 1,

the load drop detection unit is configured to: and determining that the load is applied when a state in which the infrared detection information detected by the infrared sensor is reduced by a predetermined value or more continues for a predetermined time.

3. The induction heating cooker as claimed in claim 1,

the load drop detection unit is configured to: and determining that a load is applied when the infrared detection information detected by the infrared sensor does not rise for a predetermined time or more.

4. The induction heating cooker according to claim 1 or 2,

the control unit is configured to: when the cooking time measured by the 1 st timer unit is equal to or less than the 1 st elapsed set time, and the scorch detection unit outputs the scorch detection information, the heating operation of the inverter circuit is controlled to perform temperature adjustment so that the infrared detection information becomes a value close to a predetermined set value within a range not exceeding the predetermined set value, and the reference for detecting the load application by the load application detection unit is increased as compared with the case where the temperature adjustment is not performed.

5. An induction heating cooker according to any one of claims 1 to 3,

the induction heating cooker comprises:

when the load application detector detects that a load is applied after the cooking time measured by the 1 st timer unit exceeds the 1 st set time, the cooking time measured by the 1 st timer unit is reset and the timer is restarted.

6. The induction heating cooker according to claim 4,

the induction heating cooker comprises:

when the load application detector detects that a load is applied after the cooking time measured by the 1 st timer unit exceeds the 1 st set time, the cooking time measured by the 1 st timer unit is reset and the timer is restarted.