JPWO2011161954A1 - Induction heating cooker - Google Patents

Abstract

The induction heating cooker according to the present invention includes an infrared sensor (5) that detects infrared rays emitted from the cooking vessel (2) and transmitted through the top plate (1), and a cooking vessel (2) based on the output of the infrared sensor (5). A temperature calculation unit (11) for calculating a calculated temperature (Tb) corresponding to the bottom surface temperature (Ta) of the steel sheet, and when the calculated temperature (Tb) exceeds the control temperature (T), the heating output is suppressed, and the control temperature (T) A heating control unit (10) that controls the inverter circuit (9) so that it is heated at a predetermined heating output and a disturbance light determination unit (12) that determines the presence or absence of the influence of disturbance light. The light discriminating unit (12) discriminates the presence or absence of disturbance light based on the change state of the calculated temperature (Tb) with the passage of time, and when the calculated temperature (Tb) exceeds the control temperature (T), the disturbance If the light discriminating unit (12) discriminates that there is disturbance light, control Degree (T) of the ambient light determination unit (12) is changed to a higher control temperature (T1) calculated temperature (Tb) when it is determined that there is disturbance light.

Description

  The present invention relates to an induction heating cooker that induction-heats a cooking container.

  2. Description of the Related Art In recent years, induction heating cookers that induction-heat cooking containers such as cooking containers and frying pans with a heating coil have been widely used in general households and commercial kitchens.

  FIG. 6 is a block diagram showing a configuration of a conventional induction heating cooker 20 described in Patent Document 1. As shown in FIG. As shown in FIG. 6, the induction heating cooker 20 includes a top plate 14 on which a cooking vessel 13 that heats the food is placed, and an infrared sensor that detects infrared rays 21 that are emitted from the cooking vessel 13 and pass through the top plate 14. 15, a temperature detection unit 16 that converts the output signal 22 of the infrared sensor 15 output based on the radiant energy of the infrared ray 21 received by the infrared sensor 15 into the temperature of the cooking vessel 13, and induction for heating the cooking vessel 13 A heating coil 17 that generates a magnetic field, a heating control unit 18 that controls the high frequency current of the heating coil 17 based on temperature information of the temperature detection unit 16 to control the amount of heating power of the cooking container 13, and the heating control unit 18 is heated. And an input unit 19 for inputting the above conditions. The infrared sensor 15 is shifted from the center of the heating coil 17 and arranged near the inner periphery of the heating coil 17 on the input unit 19 side, thereby measuring the bottom surface temperature of the cooking container 13 having a temperature higher than the center of the heating coil 17. In addition, the influence of infrared rays from other than the cooking container 13 can be reduced, and the temperature detection accuracy of the temperature detector 15 is improved.

  Here, when the infrared ray 21 radiated from the cooking container 13 reaches the infrared sensor 15, the infrared sensor 15 outputs an output signal 22 having a corresponding magnitude. The heating power of the heating coil 17 is controlled according to the magnitude of the output signal 22. Strictly speaking, the infrared rays radiated from the cooking container 13 are divided into infrared rays that are transmitted through the lower surface of the top plate 14 and infrared rays that are reflected from the lower surface of the top plate 14, and the transmitted infrared rays are provided below the top plate 14. The infrared sensor 15 is reached. The infrared light reflected by the lower surface of the top plate 14 is further reflected by the upper surface of the top plate 14 and reaches the infrared sensor 15. These operations are repeated and the radiant energy received by the infrared sensor 15 is converted into a temperature by the temperature detector 16.

JP 2008-262719 A

  However, since the top plate 14 of the above-described conventional induction heating cooker 20 is made of glass, sunlight 23 (hereinafter also referred to as disturbance light 23) or the like from the lateral direction or obliquely upward direction of the heating coil 17 is generated. Infrared rays from other than the cooking vessel 13 are input to the infrared sensor 15 by being transmitted through the top plate 14 or being repeatedly reflected and transmitted within the top plate 14. A noise signal output from the infrared sensor 15 in response to the disturbance light 23 is input to the temperature detection unit 16 as an output signal 22. As a result, since the control signal 24 input from the temperature detection unit 16 to the heating control unit 18 performs control corresponding to the noise signal, a malfunction occurred in the induction heating cooker. For example, since the disturbance light 23 is generated, there is a problem that the cooking container 13 is not heated although it is at room temperature.

  The present invention solves the above-described problem, and enables the infrared sensor 15 to accurately measure the bottom surface temperature of the cooking container 13 even if the infrared sensor 15 is affected by infrared rays coming from other than the cooking container 13. An object of the present invention is to provide an induction heating cooker capable of accurately heating the cooking container 13 to a user's desired temperature.

An induction heating cooker according to the present invention includes a top plate formed of a material on which a cooking vessel is placed and which transmits infrared rays, a heating coil that heats the cooking vessel, and an inverter circuit that supplies high-frequency current to the heating coil. An infrared sensor that is disposed below the top plate and detects infrared rays emitted from the bottom surface of the cooking container; and a heating output of the inverter circuit is set to a heating output, and an output signal of the infrared sensor A temperature calculation unit that calculates a bottom surface temperature of the cooking container based on the heating operation is stopped when the calculated temperature calculated by the temperature calculation unit exceeds a set control temperature, or the heating output is set to the set heating A heating control unit that controls the inverter circuit so as to reduce the heating output to be lower than the output, and a shadow of disturbance light based on the calculated temperature. And a disturbance light determination unit for determining the presence or absence of,
When the heating control unit determines that the disturbance light determination unit has an influence of disturbance light when the calculated temperature exceeds the control temperature,
The control temperature is changed to a temperature higher than the calculated temperature when the disturbance light determination unit determines that there is an influence of disturbance light.

  Further, in the induction heating cooker, the disturbance light determination unit, when the calculated temperature exceeds the control temperature and the heating operation is stopped or is reduced to a heating output lower than the set heating output, When the rising gradient of the calculated temperature exceeds a predetermined rising gradient, it is determined that there is an influence of disturbance light.

  Further, in the induction heating cooker, the disturbance light determination unit, when the calculated temperature exceeds the control temperature and the heating operation is stopped or is reduced to a heating output lower than the set heating output, When the temperature increase width of the calculated temperature in the first predetermined time width is measured every time the third predetermined time width elapses, and the temperature increase width continuously exceeds the predetermined threshold in the second predetermined time width, the disturbance It is characterized by determining that there is an influence of light.

  Furthermore, in the induction heating cooker, when the calculated temperature exceeds the control temperature, the disturbance light determination unit determines that the disturbance light determination unit has an influence of disturbance light. The control temperature is changed to a temperature higher by a predetermined value than the calculated temperature when it is determined that there is an influence of light.

  Furthermore, in the induction heating cooker, when the calculated temperature exceeds the control temperature, the disturbance light determination unit determines that the disturbance light determination unit has an influence of disturbance light. The control temperature is changed to a temperature higher than the control temperature by a difference between the calculated temperature when it is determined that there is an influence of light and a reference temperature corresponding to room temperature.

  According to the induction heating cooker according to the present invention, the bottom temperature of the cooking container is accurately detected by the infrared sensor, and the bottom temperature of the cooking container is low even if there is an influence of infrared rays coming from other than the bottom of the cooking container. In this case, the cooking container can be heated, and the bottom surface temperature of the cooking container can be accurately controlled to the set temperature regardless of the influence of ambient light.

It is a block diagram which shows the structure of the induction heating cooking appliance which concerns on the 1st Embodiment and 2nd Embodiment of this invention. (A) is a graph explaining basic operation | movement of the induction heating cooking appliance which concerns on 1st Embodiment of FIG. 1, and 2nd Embodiment, Comprising: The relationship between elapsed time and the bottom face temperature Ta of the cooking vessel 2 is shown. It is a graph, (b) corresponds to (a), is a graph showing the relationship between the elapsed time and the calculated temperature Tb of the temperature calculation unit 11, (c) corresponds to (a), the elapsed time and the inverter It is a graph which shows the relationship with the heating output P of the circuit. (A) is a graph which shows the relationship between the bottom face temperature Ta of the cooking container 2 heated with the induction heating cooking appliance 2 which concerns on 1st Embodiment of FIG. 1, and elapsed time, (b) is (a) and It is a graph which shows the relationship between elapsed time and the calculated temperature Tb with the elapsed time axis in common, and (c) shows the relationship between the elapsed time and the heating output P of the inverter circuit 9 with (a) and the elapsed time axis in common. (D) is a graph showing the relationship between the elapsed time and the temperature rise width ΔTb with respect to the calculated temperature Tb before the first predetermined time width Δt0 of the calculated temperature Tb, with the elapsed time axis in common with (a). It is. (A) is the graph which shows the relationship between elapsed time and bottom face temperature Ta of the cooking container 2, in the cooking container 2 of the induction heating cooking appliance which concerns on 1st Embodiment of FIG. 1, (b) is (a). Is a graph showing the relationship between the elapsed time and the calculated temperature Tb, (c) is a graph corresponding to (a), showing the relationship between the elapsed time and the heating output P of the inverter circuit 9, ( d) is a graph corresponding to (a) and showing the relationship between the elapsed time and the temperature rise width ΔTb with respect to the calculated temperature Tb before the first predetermined time width Δt0 of the calculated temperature Tb. (A) is a graph which shows the relationship between bottom face temperature Ta of cooking container 2 heated with the induction heating cooking appliance which concerns on 2nd Embodiment of FIG. 1, and elapsed time, (b) is (a) and progress. It is a graph which shows the relationship between elapsed time and calculated temperature Tb which makes a time axis common, (c) makes the elapsed time axis common with (a), and shows the relationship between elapsed time and the heating output P of the inverter circuit 9. (D) is a graph showing the relationship between the elapsed time and the temperature rise width ΔTb with respect to the calculated temperature Tb before the first predetermined time width Δt0 of the calculated temperature Tb, with the elapsed time axis in common with (a). It is. It is a block diagram which shows the structure of the conventional induction heating cooking appliance.

According to a first aspect of the present invention, there is provided a top plate formed of a material on which a cooking vessel is placed and transmitting infrared rays, a heating coil for heating the cooking vessel, an inverter circuit for supplying a high frequency current to the heating coil, and the top plate And an infrared sensor that detects infrared rays radiated from the bottom surface of the cooking container, and a heating output of the inverter circuit is set to a heating output, and the cooking container is based on an output signal of the infrared sensor. A temperature calculation unit that calculates a bottom surface temperature of the liquid crystal, and heating operation is stopped when the calculated temperature calculated by the temperature calculation unit exceeds a set control temperature, or the heating output is lower than the set heating output A heating control unit that controls the inverter circuit so as to reduce the output, and whether or not there is an influence of disturbance light based on the calculated temperature Comprising a disturbance light determination unit, and,
When the heating control unit determines that the disturbance light determination unit has an influence of disturbance light when the calculated temperature exceeds the control temperature,
The control temperature is changed to a temperature higher than the calculated temperature when the disturbance light determination unit determines that there is an influence of disturbance light.

  According to this configuration, when there is no influence of disturbance light on the infrared sensor and the calculated temperature exceeds the control temperature, the heating output of the inverter circuit is controlled so as not to exceed the control temperature. On the other hand, when the temperature of the cooking container is low and the calculated temperature exceeds the control temperature due to the influence of ambient light on the infrared sensor, the set control temperature is set to a higher control temperature so that it is not affected by the ambient light. And changed. For this reason, if the bottom surface temperature of the cooking container is low even when it is affected by ambient light, the cooking container can be heated, and the temperature at the bottom of the pan can be adjusted with an infrared sensor regardless of the presence of external light. Detection is performed with high accuracy, and the bottom surface temperature of the cooking container is controlled to be a set temperature.

In the second invention, in particular, in the disturbance light determination unit of the first invention, the calculated temperature exceeds the control temperature and the heating operation is stopped or the heating power is lowered to a lower heating power than the set heating power. In this case, when the rising gradient of the calculated temperature exceeds a predetermined rising gradient, it is determined that there is an influence of ambient light.
According to this configuration, it is possible to accurately determine the presence or absence of disturbance light with a simple configuration.

  In the third aspect of the invention, in particular, in the disturbance light determination unit of the second aspect of the invention, the calculated temperature exceeds the control temperature and the heating operation is stopped or the heating output is lowered to a lower heating output than the set heating output. The temperature rise width of the calculated temperature in the first predetermined time width is measured each time a third predetermined time width elapses, and the temperature rise width is continuously set to a predetermined threshold value in the second predetermined time width. When exceeding, it is determined that there is an influence of disturbance light.

  According to this configuration, it is possible to accurately determine the presence or absence of disturbance light with a simple configuration.

  According to a fourth aspect of the invention, in particular, the heating control unit according to any one of the first to third aspects of the invention is such that when the calculated temperature exceeds the control temperature, the disturbance light determination unit has an influence of disturbance light. If determined, the control light is changed to a temperature higher than the calculated temperature when the disturbance light determination unit determines that there is an influence of disturbance light.

  According to this configuration, the magnitude of the influence of disturbance light can be detected and the control temperature can be corrected based on the magnitude of the influence of disturbance light. It is possible to control with high accuracy.

  In the fifth invention, in particular, when the heating temperature control unit of the fourth invention determines that the disturbance light determination unit has an influence of disturbance light when the calculated temperature exceeds the control temperature, the disturbance light determination The control temperature is changed to a temperature higher than the control temperature by a difference between the calculated temperature when the unit determines that there is an influence of ambient light and a reference temperature corresponding to room temperature.

  According to this configuration, the magnitude of the influence of disturbance light can be detected and the control temperature can be corrected based on the magnitude of the influence of disturbance light. It is possible to control with high accuracy.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, this invention is not limited by this embodiment.

First embodiment.
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a first embodiment of the present invention.

  As shown in FIG. 1, the induction heating cooking appliance which concerns on the 1st Embodiment of this invention is the heating which heats the top plate 1 which mounted the cooking vessel 2 and formed with the material which permeate | transmits infrared rays, and the cooking vessel 2 The coil 3, the inverter circuit 9 for supplying a high-frequency current to the heating coil 3, the infrared sensor 5 that is disposed below the top plate and detects infrared rays emitted from the bottom surface of the cooking vessel 2, and the heating output P of the inverter circuit 9 are A temperature calculation unit 11 that calculates the bottom surface temperature Ta of the cooking container 2 based on the infrared detection signal 6 that is output from the infrared sensor 5 and the calculated temperature calculated by the temperature calculation unit 11 so that the heating output P1 is set. When Tb exceeds the set control temperature T, the heating operation is stopped, or the heating output P is decreased to the heating output P2 lower than the set heating output P1. A heating control unit 10 that controls the digital circuit 9 and a disturbance light determination unit 12 that determines the presence or absence of the influence of disturbance light based on the calculated temperature Tb. The heating control unit 10 has a calculated temperature Tb that exceeds the control temperature. If the disturbance light determination unit 12 determines that there is an influence of disturbance light, the control temperature T is set to a control temperature T1 higher than the calculated temperature Tb when the disturbance light determination unit 12 determines that there is an influence of disturbance light. .

  Moreover, in the induction heating cooking appliance which concerns on the 1st Embodiment of this invention, the disturbance light discrimination | determination part 12 exceeds the control temperature T, and heating lower than the heating output P1 set whether the heating operation is stopped or set. In the case where the output P2 is decreased, when the rising gradient m of the calculated temperature Tb exceeds the predetermined rising gradient m1, it is determined that there is an influence of disturbance light. Here, the gradient m is a change value of the calculated temperature with respect to a predetermined unit time, that is, a value obtained by dividing the change value of the calculated temperature by the unit time. Moreover, output, such as a heating output, means power or a power value.

  Moreover, in the induction heating cooking appliance which concerns on the 1st Embodiment of this invention, the disturbance light discrimination | determination part 12 exceeds the control temperature T, and the heating output lower than the set heating output whether the heating operation is stopped or set. When the temperature is decreased to P2, the temperature increase width ΔTb of the calculated temperature Tb in the first predetermined time width Δt0 is measured every time the third predetermined time width Δt2 elapses, and the temperature increase width ΔTb is the second predetermined time. An induction heating cooker characterized by determining that there is an influence of disturbance light when the predetermined threshold A is continuously exceeded in the width Δt1.

  In FIG. 1, the induction heating cooker includes an operation unit 4 for inputting conditions for a user to perform heating, and a rectifying and smoothing unit 8 for converting an AC voltage supplied from a commercial power supply 7 into a DC voltage. .

  Similar to the conventional induction heating cooker 20 shown in FIG. 6, the top plate 1 forms the upper surface of a box-shaped outer shell (not shown) of the induction heating cooker. The cooking container 2 is placed on the top plate 1. At that time, the cooking container 2 is placed at a position facing the heating coil 3. The top plate 1 is made of an electrically insulating material having heat resistance such as crystallized ceramics that transmits infrared rays.

  The heating coil 3 is divided into two concentric circles, and includes an outer coil 3a and an inner coil 3b connected in series. A gap is provided between the outer coil 3a and the inner coil 3b. A high frequency current is supplied to the heating coil 3 from an inverter circuit 9 described later, and a high frequency magnetic field is generated by the high frequency current. An eddy current is generated on the bottom surface of the cooking vessel 2 that has received a high-frequency magnetic field, and the cooking vessel 2 is heated by Joule heat generated by the eddy current.

  The infrared sensor 5 is provided below the top plate 1. Infrared radiation radiated from the middle in the radial direction of the bottom surface of the cooking container 2 is guided downward from the gap between the outer coil 3a and the inner coil 3b, and the infrared sensor 5 is provided so as to receive the guided infrared radiation. It is done. At this position, since the high frequency magnetic field of the heating coil 3 is stronger than the center of the heating coil 3, it is possible to detect the bottom surface temperature Ta that is substantially the highest temperature of the bottom surface temperature Ta of the cooking vessel 2 or higher than the center of the heating coil 3. . The infrared rays radiated from the bottom surface of the cooking container 2 enter the top plate 1 and pass through, and then are received by the infrared sensor 5 through the gap between the outer coil 3a and the inner coil 3b. The infrared sensor 5 detects the received infrared rays and outputs an infrared detection signal 6 corresponding to the detected amount of infrared rays, that is, the bottom surface temperature Ta of the cooking container, to the temperature calculation unit 11.

  In the main body of the induction heating cooker, a rectifying / smoothing unit 8 that converts an AC voltage supplied from the commercial power supply 7 into a DC voltage, and a DC voltage supplied from the rectifying / smoothing unit 8 to generate a high-frequency current are generated. An inverter circuit 9 that outputs a high-frequency current to the heating coil 3 is provided.

  The rectifying / smoothing unit 8 includes a full-wave rectifier 81 including a bridge diode, a choke coil 82 having one end connected to the positive-side output terminal of the full-wave rectifier 81, the other end of the choke coil 82, and the negative electrode of the full-wave rectifier 81. A low-pass filter including a smoothing capacitor 83 connected between the output terminals is provided.

  Between the output terminals of the rectifying and smoothing unit 8, a switching element 91 (in the present embodiment, for example, an insulated gate bipolar transistor) and the heating coil 3 that constitute the inverter circuit 9 are connected in series. The inverter circuit 9 further includes a diode 92 connected in antiparallel to the switching element 91 and a resonance capacitor 93 connected in parallel with the heating coil 3. The inverter circuit 9 supplies the high frequency current generated by the resonance circuit of the heating coil 3 and the resonance capacitor 93 to the heating coil 3 when the switching element 91 is turned on / off.

  The top plate 1 is provided with an operation unit 4 including a plurality of switches on the surface operated by the user. For example, a heating start / stop switch for instructing the induction heating cooker to start and stop heating by the user, and a temperature that is automatically controlled so that the temperature of the cooking container becomes a control temperature (for example, 160 ° C., 180 ° C.) Automatic temperature adjustment function selection switch for selecting an adjustment mode, and a temperature setting switch (not shown) for instructing the control temperature of the cooking container when the temperature adjustment mode is selected by the automatic temperature adjustment function selection switch and heated. Is included in the operation unit 4.

  When heating is started, the heating control unit 10 starts heating at the set output P1 that is the set heating output, and is the control temperature T transmitted from the operation unit 4 and the output value of the temperature calculation unit 11. The calculated temperature Tb is compared, and when the calculated temperature Tb exceeds the control temperature T, the switching element 91 is turned off and the heating operation of the inverter 9 is stopped. Thus, the bottom surface temperature of the cooking container 2 is controlled so as not to exceed the control temperature T set by the operation unit 4. When the calculated temperature Tb exceeds the control temperature T, the heating control unit 10 turns off the switching element 91 and stops the heating operation of the inverter 9 when the calculated temperature Tb exceeds the control temperature T. The heating output P may be lowered to a heating output P2 that is smaller than the set heating output P1, and the control temperature T may be controlled to be equal to or lower than the calculated temperature Tb.

  The disturbance light determination unit 12 has a case where the calculated temperature Tb, which is the output value of the temperature calculation unit 11, exceeds the control temperature T and the heating operation is stopped or the heating output P is suppressed to a value lower than the set output P1. The presence / absence of ambient light is determined based on the magnitude of the rising gradient m over time of the calculated temperature Tb (hereinafter also referred to as the rising gradient m of the calculated temperature Tb when the heating output P is suppressed). For example, when the rising gradient m of the calculated temperature Tb when the heating output P is suppressed exceeds the predetermined rising gradient m1, the disturbance light determining unit 12 determines that the disturbance light is present, and the control temperature T Is changed to a second control temperature T1 higher than the control temperature T. The predetermined ascending slope m1 can be set to, for example, zero or a negative value near zero.

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

  When the user instructs the start of heating by the operation unit 4, the heating control unit 10 operates the inverter circuit 9 to supply a high frequency current to the heating coil 3. A high frequency magnetic field is generated from the heating coil 3 by this high frequency current, and heating of the cooking vessel 2 placed almost at the center on the heating coil is started.

  The infrared sensor 5 detects infrared rays emitted from the bottom surface of the cooking vessel 2 and outputs an infrared detection signal 6 based on the detected amount of infrared rays. The temperature calculation unit 11 that has received the infrared detection signal 6 calculates the bottom surface temperature Ta of the cooking vessel 2.

  The heating control unit 10 controls the heating output P of the inverter circuit 9 so that the bottom surface temperature Ta of the cooking container 2 is controlled to the set temperature Ts set by the operation unit 4. The heating control unit 10 changes the conduction time of the drive signal of the switching element 91 in order to control the output of the inverter control circuit 9.

  Fig.2 (a) is a graph explaining the basic operation | movement of the induction heating cooking appliance which concerns on 1st Embodiment of FIG. 1, Comprising: It is a graph which shows the relationship between elapsed time and bottom face temperature Ta of the cooking vessel 2. FIG. 2 (b) corresponds to FIG. 2 (a), and is a graph showing the relationship between the elapsed time and the calculated temperature Tb of the temperature calculator 11, and FIG. 2 (c) corresponds to FIG. 2 (a). 4 is a graph showing the relationship between the elapsed time and the heating output P of the inverter circuit 9.

  FIG. 2A and FIG. 2C show that the heating output P of the inverter circuit 9 starts heating at the preset output P1 at time t20. When the bottom surface temperature Ta exceeds the set temperature Ts, the heating operation of the inverter circuit 9 is stopped, and when the bottom surface temperature Ta falls below the set temperature Ts at the time t22, the inverter circuit 9 resumes the heating operation with the set output P1. . Thereafter, the bottom surface temperature Ta exceeds the set temperature Ts at the time t23 and falls below the set temperature Ts at the time t24. Thereafter, such control is repeated.

  FIG. 2B shows a control operation performed by the temperature calculation unit 11 and the heating control unit 10 in order to realize the control described in FIG. That is, in FIG. 2B, the calculated temperature Tb corresponding to the bottom surface temperature Ta of the cooking container 1 is controlled corresponding to the set temperature Ts set by the operation unit 4 after the heating operation is started at the time t20. It is shown that the temperature T is controlled. Similar to the control operation described in FIG. 2A, the calculated temperature Tb curve once exceeds the control temperature T, and then the calculated temperature Tb falls below the control temperature T at time t22. Thereafter, the calculated temperature Tb exceeds the control temperature T at time t23 and falls below the control temperature T at time t24. The same applies thereafter.

  FIG. 2 (c) shows the relationship between the heating output P of the inverter circuit 9 and the elapsed time. The period when the calculated temperature Tb in FIG. 2 (b) is lower than the control temperature T, for example, from the time point t20. During the period t21, the period from time t22 to time t23, the period from time t24 to time t25, and the like, the heating output P of the inverter circuit 9 performs the heating operation with the set output P1 by the drive signal from the heating control unit 10. By driving the inverter circuit 9, a high-frequency current due to the on / off operation of the switching element flows through the heating coil 3, and the cooking vessel 2 generates heat. On the other hand, the switching element 91 is off during a period in which the calculated temperature Tb is higher than the control temperature T, for example, a period from the time t21 to the time t22, a period from the time t23 to the time t24, a period from the time t25 to the time t26, and the like. The heating control unit 10 controls the state so that the heating operation of the inverter circuit 9 is stopped. Thus, the inverter circuit 9 is controlled so that the bottom surface temperature Ta of the cooking container 2 becomes substantially the set temperature Ts by repeating the heating operation stop and the heating operation at the set output P1. Instead of stopping the heating operation, the bottom surface temperature Ta of the cooking container 2 may be operated with a low heating output P2 that quickly decreases to a temperature lower than the set temperature Ts.

  Next, the case where the calculated temperature Tb is equal to or higher than the control temperature T due to the influence of infrared rays coming from other than the cooking container 2 even though the cooking container 2 is at room temperature before the start of heating will be described.

  In the case of this condition, if the operation description in FIG. 2 is applied, the relationship that the calculated temperature Tb of the temperature calculation unit 11 is equal to or higher than the control temperature T is established even when heating is started. Therefore, the heating control unit 10 does not start the heating operation of the inverter circuit 9 and the high frequency current does not flow to the heating coil 3, so that the cooking container 2 is not heated and remains at room temperature.

  Below, the method of solving the said subject is demonstrated.

  Fig.3 (a) is a graph which shows the relationship between the bottom face temperature Ta of the cooking container 2 heated with the induction heating cooking appliance 2 which concerns on 1st Embodiment of FIG. 1, and elapsed time. FIG. 3B is a graph showing the relationship between the elapsed time and the calculated temperature Tb with the elapsed time axis in common with FIG. FIG. 3C is a graph showing the relationship between the elapsed time and the heating output P of the inverter circuit 9 with the elapsed time axis in common with FIG. FIG. 3D is a graph showing the relationship between the elapsed time axis and the temperature rise width ΔTb with respect to the calculated temperature Tb before the first predetermined time width Δt0 of the calculated temperature Tb with FIG. is there.

  FIG. 3A shows that heating is actually started at time t32. Further, the subsequent change of the bottom surface temperature Ta of the cooking container 2 with the passage of time is the same as described with reference to FIG.

  In FIG. 3B and FIG. 3C, the temperature Tb calculated by the temperature calculation unit 11 at the time t30 that is a first predetermined time width Δt0 (for example, 60 seconds) before the start of heating (time t32) is shown. Since the temperature is equal to or higher than the control temperature T, it is indicated that heating is not started even though a heating start command is input in the operation unit 4. Thereafter, after time t32, the control temperature T is changed to a control temperature T1 higher than the control temperature T by a predetermined temperature. Heating is started at time t32 when the control temperature T1 exceeds the calculated temperature Tb. When the control temperature T1 does not exceed the calculated temperature Tb, the control temperature T1 is changed to a control temperature T2 higher than the control temperature T1 by a predetermined temperature. In this way, the control temperature T is changed to a high level until the calculated temperature Tb is exceeded, and the heating operation is started. Subsequent operations are the same as those described with reference to FIG.

  FIG. 3C shows the relationship between the heating output P of the inverter circuit 9 and the elapsed time. As shown in the figure, the period in which the calculated temperature Tb in FIG. 3B is lower than the control temperature T1, for example, the period from the time point t32 to the time point t33, the period from the time point t34 to the time point t35, etc. 9 is a heating state. On the other hand, the inverter circuit 9 stops the heating operation during a period in which the calculated temperature Tb is higher than the control temperature T1, for example, a period from time t33 to time t34, a period from time t35 to time t36, and the like.

  FIG. 3D shows the relationship between the temperature rise width ΔTb of the calculated temperature Tb and the elapsed time with respect to the value before the first predetermined time width Δt0 has elapsed. With reference to this figure, the determination of the presence or absence of the influence of disturbance light in the disturbance light determination unit 12 will be described. When the relationship that the calculated temperature Tb of the temperature calculation unit 11 is equal to or higher than the control temperature T is established at the time t30 before the start of heating, the disturbance light determination unit 12 calculates the first predetermined time width Δt0 before the time t31. The temperature Tb is stored, and the temperature increase width ΔTb of the calculated temperature Tb at the time t31 with respect to the calculated temperature Tb before the first predetermined time width Δt0 from the stored time t31 is calculated. The amount of infrared rays coming from other than the cooking container 2 does not depend on the bottom surface temperature Ta of the cooking container 2 and does not change, and the temperature rise ΔTb is almost zero. When the calculated temperature Tb exceeds the control temperature T and the heating operation is stopped or is decreased to the heating output P2 lower than the set output P1, the ambient light determining unit 12 calculates the calculated temperature Tb in the first predetermined time width Δt0. Is measured every time a third predetermined time width Δt2 (for example, 1 second) elapses, and the temperature increase width ΔTb is continuously measured for the second predetermined time width Δt1 (for example, 90 seconds) for the threshold A. Is exceeded, it is determined that the rising gradient m of the calculated temperature Tb during this period exceeds the predetermined temperature gradient m1, and the disturbance light determination unit 12 is determined to be influenced by infrared rays from other than the cooking container 2. ing. The threshold A may be set to a negative value near zero. When the disturbance light determination unit 12 determines that there is an influence of disturbance light, as shown in FIG. 3B, the disturbance light determination unit 12 determines the control temperature T from the calculated temperature Tb when the determination is made. Change to a higher control temperature T1.

  As described above, by changing the control temperature T to the control temperature T1 that is higher than the calculated temperature Tb when the determination is made, the calculated temperature Tb of the temperature calculating unit 11 falls below the control temperature T1, and the temperature calculating unit 11 The high frequency current is supplied to the heating coil 3 until the calculated temperature Tb becomes equal to or higher than the control temperature T1.

  Thereafter, based on the comparison result between the calculated temperature Tb of the temperature calculator 11 and the control temperature T1, the heating operation of the inverter circuit 9 is started and stopped, and the bottom surface temperature Ta of the cooking vessel 2 is controlled.

  Here, the control temperature T <b> 1 described above can be determined by previously measuring the influence on the infrared detection signal 6 when the ambient light such as sunlight is irradiated. For example, the control temperature T1 is set in advance to a value that is larger by a predetermined value than the calculated temperature Tb when the disturbance light considered to be maximum in the normal use state is irradiated to the induction heating cooker. In this case, the larger the predetermined value, the less affected by disturbance light, but the difference from the control temperature T becomes large and the bottom temperature Ts of the cooking container becomes higher than the set temperature. It can be set appropriately in consideration of being easily affected.

  Next, the case where the calculated temperature Tb is higher than the control temperature T due to the influence of infrared rays coming from the cooking container 2 where the temperature of the cooking container 2 is higher than the normal temperature before the start of heating will be described.

  In the case of this condition, when the description of the operation in FIG. 2 is applied, a relationship in which the calculated temperature Tb of the temperature calculation unit 11 is equal to or higher than the control temperature T is established even when heating is started. Therefore, since the heating control unit 10 does not drive the switching element 91 of the inverter circuit 9 and no high frequency current is input to the heating coil 3, the cooking container 2 is not heated and the temperature is lowered due to heat radiation.

  Below, the method of solving the said subject is demonstrated.

  FIG. 4A is a graph showing the relationship between the elapsed time and the bottom surface temperature Ta of the cooking container 2 in the cooking container 2 of the induction heating cooker according to the first embodiment of FIG. ) Corresponds to FIG. 4A, and is a graph showing the relationship between the elapsed time and the calculated temperature Tb of the temperature calculation unit 11, and FIG. 4C corresponds to FIG. 4A, and the elapsed time and the inverter. FIG. 4D is a graph showing the relationship between the heating output P of the circuit 9 and FIG. 4D corresponds to FIG. 4A, with respect to the calculated temperature Tb before the first predetermined time width Δt0 of the elapsed time and the calculated temperature Tb. It is a graph which shows the relationship with temperature rise width (DELTA) Tb.

  In FIG. 4A, since the bottom surface temperature Ta of the cooking container 2 exceeds the set temperature Ts set by the operation unit 4 at the time t40 before the start of heating, the heating is not started and the bottom surface temperature Ta is released by heat dissipation. Has been shown to decrease over time.

  In FIG. 4B, the calculated temperature Tb by the temperature calculating unit 11 exceeds the control temperature T based on the set temperature Ts set by the operating unit 4 at the time t40 before the start of heating. 4, the heating operation is not started in spite of the input of the heating start command. As described with reference to FIG. 4A, the calculated temperature Tb draws a descending curve due to heat dissipation as time passes, It is shown that heating of the cooking container 2 is started at time t42 when the temperature is equal to or lower than the control temperature T. The subsequent movement of the curve is the same as described with reference to FIG.

  FIG. 4C shows the relationship between the heating output P of the inverter circuit 9 and the elapsed time. The period in which the calculated temperature Tb in FIG. 4B is equal to or lower than the control temperature T, for example, from the time t42 to the time In the period t43, the period from time t44 to time t45, etc., the inverter circuit 9 performs the heating operation with the set output P1.

  FIG. 4D shows the relationship between the temperature rise width ΔTb of the calculated temperature Tb and the elapsed time with respect to the value before the first predetermined time width Δt0 has elapsed. With reference to this figure, the operation of determining the presence or absence of the influence of disturbance light in the disturbance light determination unit 12 will be described. When the relationship that the calculated temperature Tb is equal to or higher than the control temperature T is established at the time t40 before the start of heating, the ambient light determination unit 12 calculates the calculated temperature Tb from the time t40 to the time after the first predetermined time width Δt0 (time t41). The temperature rise width ΔTb is calculated. When the temperature rise width ΔTb is a negative value below the negative threshold A, the disturbance light determination unit 12 determines that the light is not affected by infrared rays from other than the cooking container 2 and the control temperature T is not changed. Is shown (see FIG. 4C).

  According to the configuration of the first embodiment described above, even when the calculated temperature Tb is equal to or higher than the control temperature T before the start of heating, the presence or absence of disturbance light based on the disturbance light determination unit 12 is determined, and the disturbance light determination unit If 12 is determined to be “no disturbance light”, the control temperature T is not changed, and if the disturbance light determination unit 12 determines that “disturbance light is present”, the control temperature T is controlled so as not to be affected by the disturbance light. Since the correction to change to the temperature T1 can be performed, heating can be started and the temperature of the cooking container 2 can be adjusted with high accuracy regardless of the presence or absence of ambient light. In addition, it is possible to accurately determine the presence or absence of ambient light by determining the gradient of the temperature change with respect to the elapsed time of the output of the infrared sensor 5 before the start of the heating operation.

Second embodiment.
Hereinafter, a second embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of an induction heating cooker according to a second embodiment of the present invention. Fig.2 (a) is a graph explaining the basic operation | movement of the induction heating cooking appliance which concerns on 2nd Embodiment of FIG. 1, Comprising: It is a graph which shows the relationship between elapsed time and bottom face temperature Ta of the cooking vessel 2. FIG. 2 (b) corresponds to FIG. 2 (a), and is a graph showing the relationship between the elapsed time and the calculated temperature Tb of the temperature calculator 11, and FIG. 2 (c) corresponds to FIG. 2 (a). 4 is a graph showing the relationship between the elapsed time and the heating output P of the inverter circuit 9.

  Note that a description of the same components and operations as those in the first embodiment will be omitted.

The induction heating cooker according to the second embodiment of the present invention is different from the induction heating cooker according to the first embodiment in that it has the following characteristic configuration. That is, in the induction heating cooker according to the present embodiment, when the calculated temperature Tb exceeds the control temperature T, the heating control unit 10 determines that the disturbance light determination unit 12 has “the influence of disturbance light”. It is characterized in that the control temperature is changed to a temperature higher by a predetermined value than the calculated temperature Tb when the disturbance light determination unit 12 determines that there is an influence of disturbance light.
Moreover, in the induction heating cooking appliance which concerns on this embodiment, when the heating control part 10 determines with the disturbance light discrimination | determination part 12 having the influence of disturbance light, when the calculated temperature Tb exceeds the control temperature T, disturbance light The control temperature T is set to a temperature higher than the control temperature by the difference (T0−Tat) between the calculated temperature T0, which is the calculated temperature Tb when the determination unit 12 determines that there is an influence of ambient light, and the reference temperature Tat corresponding to room temperature. To change.

  Fig.5 (a) is a graph which shows the relationship between the bottom face temperature Ta and elapsed time of the cooking vessel 2 heated with the induction heating cooking appliance which concerns on 2nd Embodiment of FIG. FIG. 5B is a graph showing the relationship between the elapsed time and the calculated temperature Tb with the elapsed time axis in common with FIG. FIG. 5 (c) is a graph showing the relationship between the elapsed time and the heating output P of the inverter circuit 9 with the elapsed time axis in common with FIG. 5 (a), and FIG. 5 (d) is the same as FIG. 5 (a). 6 is a graph showing the relationship between the elapsed time axis and the temperature rise width ΔTb with respect to the calculated temperature Tb before the first predetermined time width Δt0 of the calculated temperature Tb with a common elapsed time axis.

  In FIG. 5A, at time t50 before the actual heating operation is started, a heating command is input in the operation unit 4, and the bottom surface temperature Ta of the cooking container 2 is a temperature set in the operation unit 4. Although it is below Ts, heating is not started, and heating is started at time t52. The operation after the start of heating is the same as described with reference to FIGS. 2 (b) and 3 (b).

  FIG. 5B shows that at the time t50 before the start of heating, the calculated temperature Tb is equal to or higher than the control temperature T due to the influence of infrared rays coming from other than the cooking container 2, so that heating is not started. Yes. Further, it is shown that the heating is started by changing the control temperature T to the higher control temperature T2 at the time t52 when it is determined that there is ambient light. In addition, the description regarding the calculated temperature T0 which is the value of the calculated temperature Tb at the time t52 and the description regarding the control temperature T2 are described in FIG.

  FIG. 5 (c) shows the relationship between the heating output P of the inverter circuit 9 and the elapsed time, and in a period when the calculated temperature Tb in FIG. 5 (b) is lower than the control temperature T 2 higher than the control temperature T. It is shown that the inverter circuit 9 is in a heated state. That is, it is shown that heating to the cooking container 2 starts at time t52 and stops at time t53.

  FIG. 5D shows the relationship between the temperature rise width ΔTb of the calculated temperature Tb and the elapsed time with respect to the value before the first predetermined time width Δt0 has elapsed. With reference to this figure, the operation of determining the presence or absence of the influence of disturbance light in the disturbance light determination unit 12 will be described. When the relationship that the calculated temperature Tb is equal to or higher than the control temperature T is established at the time point t50 before the start of heating, the ambient light determination unit 12 performs the calculated temperature from the time point t50 to the time after the first predetermined time width Δt0 (time point t51). A temperature rise width ΔTb of Tb is calculated. Since the amount of infrared rays coming from other than the cooking vessel 2 does not normally change, the temperature rise width ΔTb is almost zero when the infrared rays from other than the cooking vessel 2 are affected. When the calculated temperature Tb exceeds the control temperature T and the heating operation is stopped or is lower than the set output P1, the ambient light determining unit 12 has a temperature increase width ΔTb of the calculated temperature Tb in the first predetermined time width Δt0. Is measured every time a third predetermined time width Δt2 (for example, 1 second) elapses, and when the temperature rise width ΔTb continuously exceeds the threshold A for the second predetermined time width Δt1 (for example, 90 seconds), disturbance The light discriminating unit 12 determines that it is affected by infrared rays from other than the cooking container 2. The threshold A may be set to a negative value near zero. As a result, as shown in FIG. 5B, the control temperature T is changed to a higher control temperature T2. Further, the control temperature T2 is calculated by the difference between the calculated temperature T0 that is the value of the temperature Tb calculated by the temperature calculation unit 11 at the time t52 when it is determined that there is an influence of disturbance light, and the reference temperature Tat. Here, for the reference temperature Tat, the room temperature may be measured with a thermistor or the like, or an average room temperature may be set. By setting the control temperature T to a control temperature T2 (= T + (T0−Tat)) that is higher by (T0−Tat), the calculated temperature Tb of the temperature calculation unit 11 is lower than the control temperature T2, and heating is performed at time t52. Is started. That is, as shown in FIGS. 5B and 5C, the inverter circuit 9 performs the heating operation until the calculated temperature Tb of the temperature calculating unit 11 becomes equal to or higher than the control temperature T2, and the cooking vessel 2 is heated. The Thereafter, based on the comparison result between the calculated temperature Tb of the temperature calculation unit 11 and the control temperature T2, the inverter circuit 9 repeats the heating operation and the heating stop to control the bottom surface temperature Ta of the cooking vessel 2.

  According to the structure of 2nd Embodiment mentioned above, since the control temperature T2 according to the magnitude | size of the influence of the infrared rays which come from other than the cooking container 2 can be determined, the precision of temperature control of the bottom face temperature Ta of the cooking container 2 is improved. It becomes possible to raise more.

  In the first embodiment and the second embodiment, the voltage resonance type single-stone inverter is used as the inverter circuit 9. However, the inverter circuit 9 is not limited to this and may be a current resonance type. Moreover, the inverter circuit 9 should just be an inverter circuit employable for induction heating provided with several switching elements, such as a 2 stone type half bridge inverter and a 4 stone type full bridge inverter.

  As described in detail above, according to the induction heating cooker according to the present invention, even if there is an influence of infrared rays coming from other than the cooking container, the cooking container can be accurately adjusted and heated to the set temperature. It is useful as a cooking device used at home.

1,14 Top plate,
2,13 Cooking container,
3, 17 Heating coil,
3a outer coil,
3b inner coil,
4 Operation part,
5, 15 Infrared sensor,
6 Infrared detection signal,
7 Commercial power supply,
8 Rectification smoothing part,
81 full wave rectifier,
82 choke coil,
83 smoothing capacitor,
9 Inverter circuit,
91 switching elements,
92 diodes,
93 Resonant capacitor,
10 Heating control unit,
11 Temperature calculator,
12 Disturbance light discrimination unit,
16 temperature detector,
18 Heating control unit,
19 Input section,
20 induction heating cooker,
21 Infrared,
22 output signal,
23 Sunlight (disturbance light),
24 control signals,
T, T2 control temperature,
Calculated temperature at T0 time t52,
Ta bottom surface temperature of the cooking container 2,
Tat reference temperature,
Tb calculated temperature,
m Increasing gradient of calculated temperature,
m1 predetermined ascending slope,
Ts set temperature,
P Heating output,
P1 setting output,
P2 reduced heating power,
ΔTb The temperature rise width with respect to the calculated temperature Tb before the predetermined time width Δt0 of the calculated temperature Tb,
Δt0 first predetermined time width,
Δt1 second predetermined time width,
Δt2 Third predetermined time width.

  The present invention relates to an induction heating cooker that induction-heats a cooking container.

  2. Description of the Related Art In recent years, induction heating cookers that induction-heat cooking containers such as cooking containers and frying pans with a heating coil have been widely used in general households and commercial kitchens.

  FIG. 6 is a block diagram showing a configuration of a conventional induction heating cooker 20 described in Patent Document 1. As shown in FIG. As shown in FIG. 6, the induction heating cooker 20 includes a top plate 14 on which a cooking vessel 13 that heats the food is placed, and an infrared sensor that detects infrared rays 21 that are emitted from the cooking vessel 13 and pass through the top plate 14. 15, a temperature detection unit 16 that converts the output signal 22 of the infrared sensor 15 output based on the radiant energy of the infrared ray 21 received by the infrared sensor 15 into the temperature of the cooking vessel 13, and induction for heating the cooking vessel 13 A heating coil 17 that generates a magnetic field, a heating control unit 18 that controls the high frequency current of the heating coil 17 based on temperature information of the temperature detection unit 16 to control the amount of heating power of the cooking container 13, and the heating control unit 18 is heated. And an input unit 19 for inputting the above conditions. The infrared sensor 15 is shifted from the center of the heating coil 17 and arranged near the inner periphery of the heating coil 17 on the input unit 19 side, thereby measuring the bottom surface temperature of the cooking container 13 having a temperature higher than the center of the heating coil 17. In addition, the influence of infrared rays from other than the cooking container 13 can be reduced, and the temperature detection accuracy of the temperature detector 15 is improved.

  Here, when the infrared ray 21 radiated from the cooking container 13 reaches the infrared sensor 15, the infrared sensor 15 outputs an output signal 22 having a corresponding magnitude. The heating power of the heating coil 17 is controlled according to the magnitude of the output signal 22. Strictly speaking, the infrared rays radiated from the cooking container 13 are divided into infrared rays that are transmitted through the lower surface of the top plate 14 and infrared rays that are reflected from the lower surface of the top plate 14, and the transmitted infrared rays are provided below the top plate 14. The infrared sensor 15 is reached. The infrared light reflected by the lower surface of the top plate 14 is further reflected by the upper surface of the top plate 14 and reaches the infrared sensor 15. These operations are repeated and the radiant energy received by the infrared sensor 15 is converted into a temperature by the temperature detector 16.

JP 2008-262719 A

  However, since the top plate 14 of the above-described conventional induction heating cooker 20 is made of glass, sunlight 23 (hereinafter also referred to as disturbance light 23) or the like from the lateral direction or obliquely upward direction of the heating coil 17 is generated. Infrared rays from other than the cooking vessel 13 are input to the infrared sensor 15 by being transmitted through the top plate 14 or being repeatedly reflected and transmitted within the top plate 14. A noise signal output from the infrared sensor 15 in response to the disturbance light 23 is input to the temperature detection unit 16 as an output signal 22. As a result, since the control signal 24 input from the temperature detection unit 16 to the heating control unit 18 performs control corresponding to the noise signal, a malfunction occurred in the induction heating cooker. For example, since the disturbance light 23 is generated, there is a problem that the cooking container 13 is not heated although it is at room temperature.

  The present invention solves the above-described problem, and enables the infrared sensor 15 to accurately measure the bottom surface temperature of the cooking container 13 even if the infrared sensor 15 is affected by infrared rays coming from other than the cooking container 13. An object of the present invention is to provide an induction heating cooker capable of accurately heating the cooking container 13 to a user's desired temperature.

An induction heating cooker according to the present invention includes a top plate formed of a material on which a cooking vessel is placed and which transmits infrared rays, a heating coil that heats the cooking vessel, and an inverter circuit that supplies high-frequency current to the heating coil. An infrared sensor that is disposed below the top plate and detects infrared rays emitted from the bottom surface of the cooking container; and a heating output of the inverter circuit is set to a heating output, and an output signal of the infrared sensor A temperature calculation unit that calculates a bottom surface temperature of the cooking container based on the heating operation is stopped when the calculated temperature calculated by the temperature calculation unit exceeds a set control temperature, or the heating output is set to the set heating A heating control unit that controls the inverter circuit so as to reduce the heating output to be lower than the output, and a shadow of disturbance light based on the calculated temperature. And a disturbance light determination unit for determining the presence or absence of,
When the heating control unit determines that the disturbance light determination unit has an influence of disturbance light when the calculated temperature exceeds the control temperature,
The control temperature is changed to a temperature higher than the calculated temperature when the disturbance light determination unit determines that there is an influence of disturbance light.

  Further, in the induction heating cooker, the disturbance light determination unit, when the calculated temperature exceeds the control temperature and the heating operation is stopped or is reduced to a heating output lower than the set heating output, When the rising gradient of the calculated temperature exceeds a predetermined rising gradient, it is determined that there is an influence of disturbance light.

  Further, in the induction heating cooker, the disturbance light determination unit, when the calculated temperature exceeds the control temperature and the heating operation is stopped or is reduced to a heating output lower than the set heating output, When the temperature increase width of the calculated temperature in the first predetermined time width is measured every time the third predetermined time width elapses, and the temperature increase width continuously exceeds the predetermined threshold in the second predetermined time width, the disturbance It is characterized by determining that there is an influence of light.

  Furthermore, in the induction heating cooker, when the calculated temperature exceeds the control temperature, the disturbance light determination unit determines that the disturbance light determination unit has an influence of disturbance light. The control temperature is changed to a temperature higher by a predetermined value than the calculated temperature when it is determined that there is an influence of light.

  Furthermore, in the induction heating cooker, when the calculated temperature exceeds the control temperature, the disturbance light determination unit determines that the disturbance light determination unit has an influence of disturbance light. The control temperature is changed to a temperature higher than the control temperature by a difference between the calculated temperature when it is determined that there is an influence of light and a reference temperature corresponding to room temperature.

  According to the induction heating cooker according to the present invention, the bottom temperature of the cooking container is accurately detected by the infrared sensor, and the bottom temperature of the cooking container is low even if there is an influence of infrared rays coming from other than the bottom of the cooking container. In this case, the cooking container can be heated, and the bottom surface temperature of the cooking container can be accurately controlled to the set temperature regardless of the influence of ambient light.

It is a block diagram which shows the structure of the induction heating cooking appliance which concerns on the 1st Embodiment and 2nd Embodiment of this invention. (A) is a graph explaining basic operation | movement of the induction heating cooking appliance which concerns on 1st Embodiment of FIG. 1, and 2nd Embodiment, Comprising: The relationship between elapsed time and the bottom face temperature Ta of the cooking vessel 2 is shown. It is a graph, (b) corresponds to (a), is a graph showing the relationship between the elapsed time and the calculated temperature Tb of the temperature calculation unit 11, (c) corresponds to (a), the elapsed time and the inverter It is a graph which shows the relationship with the heating output P of the circuit. (A) is a graph which shows the relationship between the bottom face temperature Ta of the cooking container 2 heated with the induction heating cooking appliance 2 which concerns on 1st Embodiment of FIG. 1, and elapsed time, (b) is (a) and It is a graph which shows the relationship between elapsed time and the calculated temperature Tb with the elapsed time axis in common, and (c) shows the relationship between the elapsed time and the heating output P of the inverter circuit 9 with (a) and the elapsed time axis in common. (D) is a graph showing the relationship between the elapsed time and the temperature rise width ΔTb with respect to the calculated temperature Tb before the first predetermined time width Δt0 of the calculated temperature Tb, with the elapsed time axis in common with (a). It is. (A) is the graph which shows the relationship between elapsed time and bottom face temperature Ta of the cooking container 2, in the cooking container 2 of the induction heating cooking appliance which concerns on 1st Embodiment of FIG. 1, (b) is (a). Is a graph showing the relationship between the elapsed time and the calculated temperature Tb, (c) is a graph corresponding to (a), showing the relationship between the elapsed time and the heating output P of the inverter circuit 9, ( d) is a graph corresponding to (a) and showing the relationship between the elapsed time and the temperature rise width ΔTb with respect to the calculated temperature Tb before the first predetermined time width Δt0 of the calculated temperature Tb. (A) is a graph which shows the relationship between bottom face temperature Ta of cooking container 2 heated with the induction heating cooking appliance which concerns on 2nd Embodiment of FIG. 1, and elapsed time, (b) is (a) and progress. It is a graph which shows the relationship between elapsed time and calculated temperature Tb which makes a time axis common, (c) makes the elapsed time axis common with (a), and shows the relationship between elapsed time and the heating output P of the inverter circuit 9. (D) is a graph showing the relationship between the elapsed time and the temperature rise width ΔTb with respect to the calculated temperature Tb before the first predetermined time width Δt0 of the calculated temperature Tb, with the elapsed time axis in common with (a). It is. It is a block diagram which shows the structure of the conventional induction heating cooking appliance.

According to a first aspect of the present invention, there is provided a top plate formed of a material on which a cooking vessel is placed and transmitting infrared rays, a heating coil for heating the cooking vessel, an inverter circuit for supplying a high frequency current to the heating coil, and the top plate And an infrared sensor that detects infrared rays radiated from the bottom surface of the cooking container, and a heating output of the inverter circuit is set to a heating output, and the cooking container is based on an output signal of the infrared sensor. A temperature calculation unit that calculates a bottom surface temperature of the liquid crystal, and heating operation is stopped when the calculated temperature calculated by the temperature calculation unit exceeds a set control temperature, or the heating output is lower than the set heating output A heating control unit that controls the inverter circuit so as to reduce the output, and whether or not there is an influence of disturbance light based on the calculated temperature Comprising a disturbance light determination unit, and,
When the heating control unit determines that the disturbance light determination unit has an influence of disturbance light when the calculated temperature exceeds the control temperature,
The control temperature is changed to a temperature higher than the calculated temperature when the disturbance light determination unit determines that there is an influence of disturbance light.

  According to this configuration, when there is no influence of disturbance light on the infrared sensor and the calculated temperature exceeds the control temperature, the heating output of the inverter circuit is controlled so as not to exceed the control temperature. On the other hand, when the temperature of the cooking container is low and the calculated temperature exceeds the control temperature due to the influence of ambient light on the infrared sensor, the set control temperature is set to a higher control temperature so that it is not affected by the ambient light. And changed. For this reason, if the bottom surface temperature of the cooking container is low even when it is affected by ambient light, the cooking container can be heated, and the temperature at the bottom of the pan can be adjusted with an infrared sensor regardless of the presence of external light. Detection is performed with high accuracy, and the bottom surface temperature of the cooking container is controlled to be a set temperature.

In the second invention, in particular, in the disturbance light determination unit of the first invention, the calculated temperature exceeds the control temperature and the heating operation is stopped or the heating power is lowered to a lower heating power than the set heating power. In this case, when the rising gradient of the calculated temperature exceeds a predetermined rising gradient, it is determined that there is an influence of ambient light.
According to this configuration, it is possible to accurately determine the presence or absence of disturbance light with a simple configuration.

  In the third aspect of the invention, in particular, in the disturbance light determination unit of the second aspect of the invention, the calculated temperature exceeds the control temperature and the heating operation is stopped or the heating output is lowered to a lower heating output than the set heating output. The temperature rise width of the calculated temperature in the first predetermined time width is measured each time a third predetermined time width elapses, and the temperature rise width is continuously set to a predetermined threshold value in the second predetermined time width. When exceeding, it is determined that there is an influence of disturbance light.

  According to this configuration, it is possible to accurately determine the presence or absence of disturbance light with a simple configuration.

  According to a fourth aspect of the invention, in particular, the heating control unit according to any one of the first to third aspects of the invention is such that when the calculated temperature exceeds the control temperature, the disturbance light determination unit has an influence of disturbance light. If determined, the control light is changed to a temperature higher than the calculated temperature when the disturbance light determination unit determines that there is an influence of disturbance light.

  According to this configuration, the magnitude of the influence of disturbance light can be detected and the control temperature can be corrected based on the magnitude of the influence of disturbance light. It is possible to control with high accuracy.

  In the fifth invention, in particular, when the heating temperature control unit of the fourth invention determines that the disturbance light determination unit has an influence of disturbance light when the calculated temperature exceeds the control temperature, the disturbance light determination The control temperature is changed to a temperature higher than the control temperature by a difference between the calculated temperature when the unit determines that there is an influence of ambient light and a reference temperature corresponding to room temperature.

  According to this configuration, the magnitude of the influence of disturbance light can be detected and the control temperature can be corrected based on the magnitude of the influence of disturbance light. It is possible to control with high accuracy.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, this invention is not limited by this embodiment.

First embodiment.
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a first embodiment of the present invention.

  As shown in FIG. 1, the induction heating cooking appliance which concerns on the 1st Embodiment of this invention is the heating which heats the top plate 1 which mounted the cooking vessel 2 and formed with the material which permeate | transmits infrared rays, and the cooking vessel 2 The coil 3, the inverter circuit 9 for supplying a high-frequency current to the heating coil 3, the infrared sensor 5 that is disposed below the top plate and detects infrared rays emitted from the bottom surface of the cooking vessel 2, and the heating output P of the inverter circuit 9 are A temperature calculation unit 11 that calculates the bottom surface temperature Ta of the cooking container 2 based on the infrared detection signal 6 that is output from the infrared sensor 5 and the calculated temperature calculated by the temperature calculation unit 11 so that the heating output P1 is set. When Tb exceeds the set control temperature T, the heating operation is stopped, or the heating output P is decreased to the heating output P2 lower than the set heating output P1. A heating control unit 10 that controls the digital circuit 9 and a disturbance light determination unit 12 that determines the presence or absence of the influence of disturbance light based on the calculated temperature Tb. The heating control unit 10 has a calculated temperature Tb that exceeds the control temperature. If the disturbance light determination unit 12 determines that there is an influence of disturbance light, the control temperature T is set to a control temperature T1 higher than the calculated temperature Tb when the disturbance light determination unit 12 determines that there is an influence of disturbance light. .

  Moreover, in the induction heating cooking appliance which concerns on the 1st Embodiment of this invention, the disturbance light discrimination | determination part 12 exceeds the control temperature T, and heating lower than the heating output P1 set whether the heating operation is stopped or set. In the case where the output P2 is decreased, when the rising gradient m of the calculated temperature Tb exceeds the predetermined rising gradient m1, it is determined that there is an influence of disturbance light. Here, the gradient m is a change value of the calculated temperature with respect to a predetermined unit time, that is, a value obtained by dividing the change value of the calculated temperature by the unit time. Moreover, output, such as a heating output, means power or a power value.

  Moreover, in the induction heating cooking appliance which concerns on the 1st Embodiment of this invention, the disturbance light discrimination | determination part 12 exceeds the control temperature T, and the heating output lower than the set heating output whether the heating operation is stopped or set. When the temperature is decreased to P2, the temperature increase width ΔTb of the calculated temperature Tb in the first predetermined time width Δt0 is measured every time the third predetermined time width Δt2 elapses, and the temperature increase width ΔTb is the second predetermined time. An induction heating cooker characterized by determining that there is an influence of disturbance light when the predetermined threshold A is continuously exceeded in the width Δt1.

  In FIG. 1, the induction heating cooker includes an operation unit 4 for inputting conditions for a user to perform heating, and a rectifying and smoothing unit 8 for converting an AC voltage supplied from a commercial power supply 7 into a DC voltage. .

  Similar to the conventional induction heating cooker 20 shown in FIG. 6, the top plate 1 forms the upper surface of a box-shaped outer shell (not shown) of the induction heating cooker. The cooking container 2 is placed on the top plate 1. At that time, the cooking container 2 is placed at a position facing the heating coil 3. The top plate 1 is made of an electrically insulating material having heat resistance such as crystallized ceramics that transmits infrared rays.

  The heating coil 3 is divided into two concentric circles, and includes an outer coil 3a and an inner coil 3b connected in series. A gap is provided between the outer coil 3a and the inner coil 3b. A high frequency current is supplied to the heating coil 3 from an inverter circuit 9 described later, and a high frequency magnetic field is generated by the high frequency current. An eddy current is generated on the bottom surface of the cooking vessel 2 that has received a high-frequency magnetic field, and the cooking vessel 2 is heated by Joule heat generated by the eddy current.

  The infrared sensor 5 is provided below the top plate 1. Infrared radiation radiated from the middle in the radial direction of the bottom surface of the cooking container 2 is guided downward from the gap between the outer coil 3a and the inner coil 3b, and the infrared sensor 5 is provided so as to receive the guided infrared radiation. It is done. At this position, since the high frequency magnetic field of the heating coil 3 is stronger than the center of the heating coil 3, it is possible to detect the bottom surface temperature Ta that is substantially the highest temperature of the bottom surface temperature Ta of the cooking vessel 2 or higher than the center of the heating coil 3. . The infrared rays radiated from the bottom surface of the cooking container 2 enter the top plate 1 and pass through, and then are received by the infrared sensor 5 through the gap between the outer coil 3a and the inner coil 3b. The infrared sensor 5 detects the received infrared rays and outputs an infrared detection signal 6 corresponding to the detected amount of infrared rays, that is, the bottom surface temperature Ta of the cooking container, to the temperature calculation unit 11.

  In the main body of the induction heating cooker, a rectifying / smoothing unit 8 that converts an AC voltage supplied from the commercial power supply 7 into a DC voltage, and a DC voltage supplied from the rectifying / smoothing unit 8 to generate a high-frequency current are generated. An inverter circuit 9 that outputs a high-frequency current to the heating coil 3 is provided.

  The rectifying / smoothing unit 8 includes a full-wave rectifier 81 including a bridge diode, a choke coil 82 having one end connected to the positive-side output terminal of the full-wave rectifier 81, the other end of the choke coil 82, and the negative electrode of the full-wave rectifier 81. A low-pass filter including a smoothing capacitor 83 connected between the output terminals is provided.

  Between the output terminals of the rectifying and smoothing unit 8, a switching element 91 (in the present embodiment, for example, an insulated gate bipolar transistor) and the heating coil 3 that constitute the inverter circuit 9 are connected in series. The inverter circuit 9 further includes a diode 92 connected in antiparallel to the switching element 91 and a resonance capacitor 93 connected in parallel with the heating coil 3. The inverter circuit 9 supplies the high frequency current generated by the resonance circuit of the heating coil 3 and the resonance capacitor 93 to the heating coil 3 when the switching element 91 is turned on / off.

  The top plate 1 is provided with an operation unit 4 including a plurality of switches on the surface operated by the user. For example, a heating start / stop switch for instructing the induction heating cooker to start and stop heating by the user, and a temperature that is automatically controlled so that the temperature of the cooking container becomes a control temperature (for example, 160 ° C., 180 ° C.) Automatic temperature adjustment function selection switch for selecting an adjustment mode, and a temperature setting switch (not shown) for instructing the control temperature of the cooking container when the temperature adjustment mode is selected by the automatic temperature adjustment function selection switch and heated. Is included in the operation unit 4.

  When heating is started, the heating control unit 10 starts heating at the set output P1 that is the set heating output, and is the control temperature T transmitted from the operation unit 4 and the output value of the temperature calculation unit 11. The calculated temperature Tb is compared, and when the calculated temperature Tb exceeds the control temperature T, the switching element 91 is turned off and the heating operation of the inverter 9 is stopped. Thus, the bottom surface temperature of the cooking container 2 is controlled so as not to exceed the control temperature T set by the operation unit 4. When the calculated temperature Tb exceeds the control temperature T, the heating control unit 10 turns off the switching element 91 and stops the heating operation of the inverter 9 when the calculated temperature Tb exceeds the control temperature T. The heating output P may be lowered to a heating output P2 that is smaller than the set heating output P1, and the control temperature T may be controlled to be equal to or lower than the calculated temperature Tb.

  The disturbance light determination unit 12 has a case where the calculated temperature Tb, which is the output value of the temperature calculation unit 11, exceeds the control temperature T and the heating operation is stopped or the heating output P is suppressed to a value lower than the set output P1. The presence / absence of ambient light is determined based on the magnitude of the rising gradient m over time of the calculated temperature Tb (hereinafter also referred to as the rising gradient m of the calculated temperature Tb when the heating output P is suppressed). For example, when the rising gradient m of the calculated temperature Tb when the heating output P is suppressed exceeds the predetermined rising gradient m1, the disturbance light determining unit 12 determines that the disturbance light is present, and the control temperature T Is changed to a second control temperature T1 higher than the control temperature T. The predetermined ascending slope m1 can be set to, for example, zero or a negative value near zero.

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

  When the user instructs the start of heating by the operation unit 4, the heating control unit 10 operates the inverter circuit 9 to supply a high frequency current to the heating coil 3. A high frequency magnetic field is generated from the heating coil 3 by this high frequency current, and heating of the cooking vessel 2 placed almost at the center on the heating coil is started.

  The infrared sensor 5 detects infrared rays emitted from the bottom surface of the cooking vessel 2 and outputs an infrared detection signal 6 based on the detected amount of infrared rays. The temperature calculation unit 11 that has received the infrared detection signal 6 calculates the bottom surface temperature Ta of the cooking vessel 2.

  The heating control unit 10 controls the heating output P of the inverter circuit 9 so that the bottom surface temperature Ta of the cooking container 2 is controlled to the set temperature Ts set by the operation unit 4. The heating control unit 10 changes the conduction time of the drive signal of the switching element 91 in order to control the output of the inverter control circuit 9.

  Fig.2 (a) is a graph explaining the basic operation | movement of the induction heating cooking appliance which concerns on 1st Embodiment of FIG. 1, Comprising: It is a graph which shows the relationship between elapsed time and bottom face temperature Ta of the cooking vessel 2. FIG. 2 (b) corresponds to FIG. 2 (a), and is a graph showing the relationship between the elapsed time and the calculated temperature Tb of the temperature calculator 11, and FIG. 2 (c) corresponds to FIG. 2 (a). 4 is a graph showing the relationship between the elapsed time and the heating output P of the inverter circuit 9.

  FIG. 2A and FIG. 2C show that the heating output P of the inverter circuit 9 starts heating at the preset output P1 at time t20. When the bottom surface temperature Ta exceeds the set temperature Ts, the heating operation of the inverter circuit 9 is stopped, and when the bottom surface temperature Ta falls below the set temperature Ts at the time t22, the inverter circuit 9 resumes the heating operation with the set output P1. . Thereafter, the bottom surface temperature Ta exceeds the set temperature Ts at the time t23 and falls below the set temperature Ts at the time t24. Thereafter, such control is repeated.

  FIG. 2B shows a control operation performed by the temperature calculation unit 11 and the heating control unit 10 in order to realize the control described in FIG. That is, in FIG. 2B, the calculated temperature Tb corresponding to the bottom surface temperature Ta of the cooking container 1 is controlled corresponding to the set temperature Ts set by the operation unit 4 after the heating operation is started at the time t20. It is shown that the temperature T is controlled. Similar to the control operation described in FIG. 2A, the calculated temperature Tb curve once exceeds the control temperature T, and then the calculated temperature Tb falls below the control temperature T at time t22. Thereafter, the calculated temperature Tb exceeds the control temperature T at time t23 and falls below the control temperature T at time t24. The same applies thereafter.

  FIG. 2 (c) shows the relationship between the heating output P of the inverter circuit 9 and the elapsed time. The period when the calculated temperature Tb in FIG. 2 (b) is lower than the control temperature T, for example, from the time point t20. During the period t21, the period from time t22 to time t23, the period from time t24 to time t25, and the like, the heating output P of the inverter circuit 9 performs the heating operation with the set output P1 by the drive signal from the heating control unit 10. By driving the inverter circuit 9, a high-frequency current due to the on / off operation of the switching element flows through the heating coil 3, and the cooking vessel 2 generates heat. On the other hand, the switching element 91 is off during a period in which the calculated temperature Tb is higher than the control temperature T, for example, a period from the time t21 to the time t22, a period from the time t23 to the time t24, a period from the time t25 to the time t26, and the like. The heating control unit 10 controls the state so that the heating operation of the inverter circuit 9 is stopped. Thus, the inverter circuit 9 is controlled so that the bottom surface temperature Ta of the cooking container 2 becomes substantially the set temperature Ts by repeating the heating operation stop and the heating operation at the set output P1. Instead of stopping the heating operation, the bottom surface temperature Ta of the cooking container 2 may be operated with a low heating output P2 that quickly decreases to a temperature lower than the set temperature Ts.

  Next, the case where the calculated temperature Tb is equal to or higher than the control temperature T due to the influence of infrared rays coming from other than the cooking container 2 even though the cooking container 2 is at room temperature before the start of heating will be described.

  In the case of this condition, if the operation description in FIG. 2 is applied, the relationship that the calculated temperature Tb of the temperature calculation unit 11 is equal to or higher than the control temperature T is established even when heating is started. Therefore, the heating control unit 10 does not start the heating operation of the inverter circuit 9 and the high frequency current does not flow to the heating coil 3, so that the cooking container 2 is not heated and remains at room temperature.

  Below, the method of solving the said subject is demonstrated.

  Fig.3 (a) is a graph which shows the relationship between the bottom face temperature Ta of the cooking container 2 heated with the induction heating cooking appliance 2 which concerns on 1st Embodiment of FIG. 1, and elapsed time. FIG. 3B is a graph showing the relationship between the elapsed time and the calculated temperature Tb with the elapsed time axis in common with FIG. FIG. 3C is a graph showing the relationship between the elapsed time and the heating output P of the inverter circuit 9 with the elapsed time axis in common with FIG. FIG. 3D is a graph showing the relationship between the elapsed time axis and the temperature rise width ΔTb with respect to the calculated temperature Tb before the first predetermined time width Δt0 of the calculated temperature Tb with FIG. is there.

  FIG. 3A shows that heating is actually started at time t32. Further, the subsequent change of the bottom surface temperature Ta of the cooking container 2 with the passage of time is the same as described with reference to FIG.

  In FIG. 3B and FIG. 3C, the temperature Tb calculated by the temperature calculation unit 11 at the time t30 that is a first predetermined time width Δt0 (for example, 60 seconds) before the start of heating (time t32) is shown. Since the temperature is equal to or higher than the control temperature T, it is indicated that heating is not started even though a heating start command is input in the operation unit 4. Thereafter, after time t32, the control temperature T is changed to a control temperature T1 higher than the control temperature T by a predetermined temperature. Heating is started at time t32 when the control temperature T1 exceeds the calculated temperature Tb. When the control temperature T1 does not exceed the calculated temperature Tb, the control temperature T1 is changed to a control temperature T2 higher than the control temperature T1 by a predetermined temperature. In this way, the control temperature T is changed to a high level until the calculated temperature Tb is exceeded, and the heating operation is started. Subsequent operations are the same as those described with reference to FIG.

  FIG. 3C shows the relationship between the heating output P of the inverter circuit 9 and the elapsed time. As shown in the figure, the period in which the calculated temperature Tb in FIG. 3B is lower than the control temperature T1, for example, the period from the time point t32 to the time point t33, the period from the time point t34 to the time point t35, etc. 9 is a heating state. On the other hand, the inverter circuit 9 stops the heating operation during a period in which the calculated temperature Tb is higher than the control temperature T1, for example, a period from time t33 to time t34, a period from time t35 to time t36, and the like.

  FIG. 3D shows the relationship between the temperature rise width ΔTb of the calculated temperature Tb and the elapsed time with respect to the value before the first predetermined time width Δt0 has elapsed. With reference to this figure, the determination of the presence or absence of the influence of disturbance light in the disturbance light determination unit 12 will be described. When the relationship that the calculated temperature Tb of the temperature calculation unit 11 is equal to or higher than the control temperature T is established at the time t30 before the start of heating, the disturbance light determination unit 12 calculates the first predetermined time width Δt0 before the time t31. The temperature Tb is stored, and the temperature increase width ΔTb of the calculated temperature Tb at the time t31 with respect to the calculated temperature Tb before the first predetermined time width Δt0 from the stored time t31 is calculated. The amount of infrared rays coming from other than the cooking container 2 does not depend on the bottom surface temperature Ta of the cooking container 2 and does not change, and the temperature rise ΔTb is almost zero. When the calculated temperature Tb exceeds the control temperature T and the heating operation is stopped or is decreased to the heating output P2 lower than the set output P1, the ambient light determining unit 12 calculates the calculated temperature Tb in the first predetermined time width Δt0. Is measured every time a third predetermined time width Δt2 (for example, 1 second) elapses, and the temperature increase width ΔTb is continuously measured for the second predetermined time width Δt1 (for example, 90 seconds) for the threshold A. Is exceeded, it is determined that the rising gradient m of the calculated temperature Tb during this period exceeds the predetermined temperature gradient m1, and the disturbance light determination unit 12 is determined to be influenced by infrared rays from other than the cooking container 2. ing. The threshold A may be set to a negative value near zero. When the disturbance light determination unit 12 determines that there is an influence of disturbance light, as shown in FIG. 3B, the disturbance light determination unit 12 determines the control temperature T from the calculated temperature Tb when the determination is made. Change to a higher control temperature T1.

  As described above, by changing the control temperature T to the control temperature T1 that is higher than the calculated temperature Tb when the determination is made, the calculated temperature Tb of the temperature calculating unit 11 falls below the control temperature T1, and the temperature calculating unit 11 The high frequency current is supplied to the heating coil 3 until the calculated temperature Tb becomes equal to or higher than the control temperature T1.

  Thereafter, based on the comparison result between the calculated temperature Tb of the temperature calculator 11 and the control temperature T1, the heating operation of the inverter circuit 9 is started and stopped, and the bottom surface temperature Ta of the cooking vessel 2 is controlled.

  Here, the control temperature T <b> 1 described above can be determined by previously measuring the influence on the infrared detection signal 6 when the ambient light such as sunlight is irradiated. For example, the control temperature T1 is set in advance to a value that is larger by a predetermined value than the calculated temperature Tb when the disturbance light considered to be maximum in the normal use state is irradiated to the induction heating cooker. In this case, the larger the predetermined value, the less affected by disturbance light, but the difference from the control temperature T becomes large and the bottom temperature Ts of the cooking container becomes higher than the set temperature. It can be set appropriately in consideration of being easily affected.

  Next, the case where the calculated temperature Tb is higher than the control temperature T due to the influence of infrared rays coming from the cooking container 2 where the temperature of the cooking container 2 is higher than the normal temperature before the start of heating will be described.

  In the case of this condition, when the description of the operation in FIG. 2 is applied, a relationship in which the calculated temperature Tb of the temperature calculation unit 11 is equal to or higher than the control temperature T is established even when heating is started. Therefore, since the heating control unit 10 does not drive the switching element 91 of the inverter circuit 9 and no high frequency current is input to the heating coil 3, the cooking container 2 is not heated and the temperature is lowered due to heat radiation.

  Below, the method of solving the said subject is demonstrated.

  FIG. 4A is a graph showing the relationship between the elapsed time and the bottom surface temperature Ta of the cooking container 2 in the cooking container 2 of the induction heating cooker according to the first embodiment of FIG. ) Corresponds to FIG. 4A, and is a graph showing the relationship between the elapsed time and the calculated temperature Tb of the temperature calculation unit 11, and FIG. 4C corresponds to FIG. 4A, and the elapsed time and the inverter. FIG. 4D is a graph showing the relationship between the heating output P of the circuit 9 and FIG. 4D corresponds to FIG. 4A, with respect to the calculated temperature Tb before the first predetermined time width Δt0 of the elapsed time and the calculated temperature Tb. It is a graph which shows the relationship with temperature rise width (DELTA) Tb.

  In FIG. 4A, since the bottom surface temperature Ta of the cooking container 2 exceeds the set temperature Ts set by the operation unit 4 at the time t40 before the start of heating, the heating is not started and the bottom surface temperature Ta is released by heat dissipation. Has been shown to decrease over time.

  In FIG. 4B, the calculated temperature Tb by the temperature calculating unit 11 exceeds the control temperature T based on the set temperature Ts set by the operating unit 4 at the time t40 before the start of heating. 4, the heating operation is not started in spite of the input of the heating start command. As described with reference to FIG. 4A, the calculated temperature Tb draws a descending curve due to heat dissipation as time passes, It is shown that heating of the cooking container 2 is started at time t42 when the temperature is equal to or lower than the control temperature T. The subsequent movement of the curve is the same as described with reference to FIG.

  FIG. 4C shows the relationship between the heating output P of the inverter circuit 9 and the elapsed time. The period in which the calculated temperature Tb in FIG. 4B is equal to or lower than the control temperature T, for example, from the time t42 to the time In the period t43, the period from time t44 to time t45, etc., the inverter circuit 9 performs the heating operation with the set output P1.

  FIG. 4D shows the relationship between the temperature rise width ΔTb of the calculated temperature Tb and the elapsed time with respect to the value before the first predetermined time width Δt0 has elapsed. With reference to this figure, the operation of determining the presence or absence of the influence of disturbance light in the disturbance light determination unit 12 will be described. When the relationship that the calculated temperature Tb is equal to or higher than the control temperature T is established at the time t40 before the start of heating, the ambient light determination unit 12 calculates the calculated temperature Tb from the time t40 to the time after the first predetermined time width Δt0 (time t41). The temperature rise width ΔTb is calculated. When the temperature rise width ΔTb is a negative value below the negative threshold A, the disturbance light determination unit 12 determines that the light is not affected by infrared rays from other than the cooking container 2 and the control temperature T is not changed. Is shown (see FIG. 4C).

  According to the configuration of the first embodiment described above, even when the calculated temperature Tb is equal to or higher than the control temperature T before the start of heating, the presence or absence of disturbance light based on the disturbance light determination unit 12 is determined, and the disturbance light determination unit If 12 is determined to be “no disturbance light”, the control temperature T is not changed, and if the disturbance light determination unit 12 determines that “disturbance light is present”, the control temperature T is controlled so as not to be affected by the disturbance light. Since the correction to change to the temperature T1 can be performed, heating can be started and the temperature of the cooking container 2 can be adjusted with high accuracy regardless of the presence or absence of ambient light. In addition, it is possible to accurately determine the presence or absence of ambient light by determining the gradient of the temperature change with respect to the elapsed time of the output of the infrared sensor 5 before the start of the heating operation.

Second embodiment.
Hereinafter, a second embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of an induction heating cooker according to a second embodiment of the present invention. Fig.2 (a) is a graph explaining the basic operation | movement of the induction heating cooking appliance which concerns on 2nd Embodiment of FIG. 1, Comprising: It is a graph which shows the relationship between elapsed time and bottom face temperature Ta of the cooking vessel 2. FIG. 2 (b) corresponds to FIG. 2 (a), and is a graph showing the relationship between the elapsed time and the calculated temperature Tb of the temperature calculator 11, and FIG. 2 (c) corresponds to FIG. 2 (a). 4 is a graph showing the relationship between the elapsed time and the heating output P of the inverter circuit 9.

  Note that a description of the same components and operations as those in the first embodiment will be omitted.

The induction heating cooker according to the second embodiment of the present invention is different from the induction heating cooker according to the first embodiment in that it has the following characteristic configuration. That is, in the induction heating cooker according to the present embodiment, when the calculated temperature Tb exceeds the control temperature T, the heating control unit 10 determines that the disturbance light determination unit 12 has “the influence of disturbance light”. It is characterized in that the control temperature is changed to a temperature higher by a predetermined value than the calculated temperature Tb when the disturbance light determination unit 12 determines that there is an influence of disturbance light.
Moreover, in the induction heating cooking appliance which concerns on this embodiment, when the heating control part 10 determines with the disturbance light discrimination | determination part 12 having the influence of disturbance light, when the calculated temperature Tb exceeds the control temperature T, disturbance light The control temperature T is set to a temperature higher than the control temperature by the difference (T0−Tat) between the calculated temperature T0, which is the calculated temperature Tb when the determination unit 12 determines that there is an influence of ambient light, and the reference temperature Tat corresponding to room temperature. To change.

  Fig.5 (a) is a graph which shows the relationship between the bottom face temperature Ta and elapsed time of the cooking vessel 2 heated with the induction heating cooking appliance which concerns on 2nd Embodiment of FIG. FIG. 5B is a graph showing the relationship between the elapsed time and the calculated temperature Tb with the elapsed time axis in common with FIG. FIG. 5 (c) is a graph showing the relationship between the elapsed time and the heating output P of the inverter circuit 9 with the elapsed time axis in common with FIG. 5 (a), and FIG. 5 (d) is the same as FIG. 5 (a). 6 is a graph showing the relationship between the elapsed time axis and the temperature rise width ΔTb with respect to the calculated temperature Tb before the first predetermined time width Δt0 of the calculated temperature Tb with a common elapsed time axis.

  In FIG. 5A, at time t50 before the actual heating operation is started, a heating command is input in the operation unit 4, and the bottom surface temperature Ta of the cooking container 2 is a temperature set in the operation unit 4. Although it is below Ts, heating is not started, and heating is started at time t52. The operation after the start of heating is the same as described with reference to FIGS. 2 (b) and 3 (b).

  FIG. 5B shows that at the time t50 before the start of heating, the calculated temperature Tb is equal to or higher than the control temperature T due to the influence of infrared rays coming from other than the cooking container 2, so that heating is not started. Yes. Further, it is shown that the heating is started by changing the control temperature T to the higher control temperature T2 at the time t52 when it is determined that there is ambient light. In addition, the description regarding the calculated temperature T0 which is the value of the calculated temperature Tb at the time t52 and the description regarding the control temperature T2 are described in FIG.

  FIG. 5 (c) shows the relationship between the heating output P of the inverter circuit 9 and the elapsed time, and in a period when the calculated temperature Tb in FIG. 5 (b) is lower than the control temperature T 2 higher than the control temperature T. It is shown that the inverter circuit 9 is in a heated state. That is, it is shown that heating to the cooking container 2 starts at time t52 and stops at time t53.

  FIG. 5D shows the relationship between the temperature rise width ΔTb of the calculated temperature Tb and the elapsed time with respect to the value before the first predetermined time width Δt0 has elapsed. With reference to this figure, the operation of determining the presence or absence of the influence of disturbance light in the disturbance light determination unit 12 will be described. When the relationship that the calculated temperature Tb is equal to or higher than the control temperature T is established at the time point t50 before the start of heating, the ambient light determination unit 12 performs the calculated temperature from the time point t50 to the time after the first predetermined time width Δt0 (time point t51). A temperature rise width ΔTb of Tb is calculated. Since the amount of infrared rays coming from other than the cooking vessel 2 does not normally change, the temperature rise width ΔTb is almost zero when the infrared rays from other than the cooking vessel 2 are affected. When the calculated temperature Tb exceeds the control temperature T and the heating operation is stopped or is lower than the set output P1, the ambient light determining unit 12 has a temperature increase width ΔTb of the calculated temperature Tb in the first predetermined time width Δt0. Is measured every time a third predetermined time width Δt2 (for example, 1 second) elapses, and when the temperature rise width ΔTb continuously exceeds the threshold A for the second predetermined time width Δt1 (for example, 90 seconds), disturbance The light discriminating unit 12 determines that it is affected by infrared rays from other than the cooking container 2. The threshold A may be set to a negative value near zero. As a result, as shown in FIG. 5B, the control temperature T is changed to a higher control temperature T2. Further, the control temperature T2 is calculated by the difference between the calculated temperature T0 that is the value of the temperature Tb calculated by the temperature calculation unit 11 at the time t52 when it is determined that there is an influence of disturbance light, and the reference temperature Tat. Here, for the reference temperature Tat, the room temperature may be measured with a thermistor or the like, or an average room temperature may be set. By setting the control temperature T to a control temperature T2 (= T + (T0−Tat)) that is higher by (T0−Tat), the calculated temperature Tb of the temperature calculation unit 11 is lower than the control temperature T2, and heating is performed at time t52. Is started. That is, as shown in FIGS. 5B and 5C, the inverter circuit 9 performs the heating operation until the calculated temperature Tb of the temperature calculating unit 11 becomes equal to or higher than the control temperature T2, and the cooking vessel 2 is heated. The Thereafter, based on the comparison result between the calculated temperature Tb of the temperature calculation unit 11 and the control temperature T2, the inverter circuit 9 repeats the heating operation and the heating stop to control the bottom surface temperature Ta of the cooking vessel 2.

  According to the structure of 2nd Embodiment mentioned above, since the control temperature T2 according to the magnitude | size of the influence of the infrared rays which come from other than the cooking container 2 can be determined, the precision of temperature control of the bottom face temperature Ta of the cooking container 2 is improved. It becomes possible to raise more.

  In the first embodiment and the second embodiment, the voltage resonance type single-stone inverter is used as the inverter circuit 9. However, the inverter circuit 9 is not limited to this and may be a current resonance type. Moreover, the inverter circuit 9 should just be an inverter circuit employable for induction heating provided with several switching elements, such as a 2 stone type half bridge inverter and a 4 stone type full bridge inverter.

  As described in detail above, according to the induction heating cooker according to the present invention, even if there is an influence of infrared rays coming from other than the cooking container, the cooking container can be accurately adjusted and heated to the set temperature. It is useful as a cooking device used at home.

1,14 Top plate,
2,13 Cooking container,
3, 17 Heating coil,
3a outer coil,
3b inner coil,
4 Operation part,
5, 15 Infrared sensor,
6 Infrared detection signal,
7 Commercial power supply,
8 Rectification smoothing part,
81 full wave rectifier,
82 choke coil,
83 smoothing capacitor,
9 Inverter circuit,
91 switching elements,
92 diodes,
93 Resonant capacitor,
10 Heating control unit,
11 Temperature calculator,
12 Disturbance light discrimination unit,
16 temperature detector,
18 Heating control unit,
19 Input section,
20 induction heating cooker,
21 Infrared,
22 output signal,
23 Sunlight (disturbance light),
24 control signals,
T, T2 control temperature,
Calculated temperature at T0 time t52,
Ta bottom surface temperature of the cooking container 2,
Tat reference temperature,
Tb calculated temperature,
m Increasing gradient of calculated temperature,
m1 predetermined ascending slope,
Ts set temperature,
P Heating output,
P1 setting output,
P2 reduced heating power,
ΔTb The temperature rise width with respect to the calculated temperature Tb before the predetermined time width Δt0 of the calculated temperature Tb,
Δt0 first predetermined time width,
Δt1 second predetermined time width,
Δt2 Third predetermined time width.

Claims (5)

A top plate formed of a material on which a cooking vessel is placed and which transmits infrared rays, a heating coil for heating the cooking vessel, an inverter circuit for supplying a high-frequency current to the heating coil, and the top plate disposed below the top plate An infrared sensor for detecting infrared radiation radiated from the bottom surface of the cooking container, and the heating output of the inverter circuit is set to a set heating output, and the bottom temperature of the cooking container is calculated based on the output signal of the infrared sensor. When the calculated temperature calculated by the temperature calculating unit and the temperature calculating unit exceeds a set control temperature, the heating operation is stopped or the heating output is reduced to a heating output lower than the set heating output. A heating control unit that controls the inverter circuit, and a disturbance light determination unit that determines whether or not there is an influence of disturbance light based on the calculated temperature , Equipped with a,
When the heating control unit determines that the disturbance light determination unit has an influence of disturbance light when the calculated temperature exceeds the control temperature,
An induction heating cooker, wherein the control temperature is changed to a temperature higher than the calculated temperature when the disturbance light determination unit determines that there is an influence of disturbance light.   The disturbance light determining unit, when the calculated temperature exceeds the control temperature and the heating operation is stopped or is lowered to a heating output lower than the set heating output, the rising gradient with respect to the elapsed time of the calculated temperature The induction heating cooker according to claim 1, wherein when it exceeds a predetermined ascent gradient, it is determined that there is an influence of ambient light.   The disturbance light determining unit is configured to calculate the first predetermined time width when the calculated temperature exceeds the control temperature and the heating operation is stopped or is lowered to a heating output lower than the set heating output. Measuring the temperature rise width every time a third predetermined time width elapses, and determining that there is an influence of ambient light when the temperature rise width continuously exceeds a predetermined threshold in the second predetermined time width The induction heating cooker according to claim 2 characterized by.   The heating control unit determines that the disturbance light determination unit has an influence of disturbance light when the disturbance light determination unit has an influence of disturbance light when the calculated temperature exceeds the control temperature. The induction heating cooker according to any one of claims 1 to 3, wherein the control temperature is changed to a temperature that is higher than the calculated temperature by a predetermined value.   The heating control unit determines that the disturbance light determination unit has an influence of disturbance light when the disturbance light determination unit has an influence of disturbance light when the calculated temperature exceeds the control temperature. The induction heating cooker according to claim 4, wherein the control temperature is changed to a temperature higher than the control temperature by a difference between the calculated temperature and a reference temperature corresponding to room temperature.

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