JP6131469B2 - Induction heating cooker - Google Patents

Description

  The present invention relates to an induction heating cooker that heats an object to be heated such as a cooking container.

  In recent years, induction heating cookers that induction-heat cooking containers such as pans and frying pans using a heating coil have been widely used in general households and commercial kitchens, and generally, above the heating coil when heating is started. It is configured so that it can detect whether or not a pan is placed on the. As the detection method, there is a method in which an inverter that supplies a high-frequency current to a heating coil is driven, and an output characteristic of the inverter at that time is read by a control microcomputer to detect the presence or absence of a pan (for example, see Patent Documents 1 and 2) . In addition, after detecting the absence of a pan, some inverters intermittently oscillate (for example, every 2 seconds) so that it can be detected when the pan is placed.

JP 2003-17235 A JP 2011-165552 A

  However, in the conventional configuration, when the inverter is driven in a state where there is no pan, a load is applied to the switching element or the like constituting the inverter due to the intermittent oscillation for detecting the presence or absence of the pan, and there is a risk that the deterioration of the parts is accelerated. There is a possibility that wasteful power is consumed, and even if a pan is placed after that, during the intermittent oscillation off period, it cannot be detected that the pan has been placed, and heating recovery cannot be performed immediately. There is also a problem that when the is mounted, it is heated by intermittent oscillation. In addition, even if a small-diameter pan or the like is placed at a position where the detection by the infrared sensor cannot be performed properly, it can be heated if the bonding area with the heating coil can be obtained to some extent, and the temperature cannot be controlled appropriately. It had the problem that.

  The present invention solves the above-mentioned problem, and it is possible to quickly detect the absence of a pan and to stop heating even if it is in a condition where the detection of the infrared sensor cannot be appropriately performed while heating is possible. You can notify the user to reposition the pan, reduce the load on the electronic parts, suppress the consumption of wasted power, and, for example, metal such as knives and forks Even if small items are placed on the heating coil, they can be prevented from being heated to a high temperature, and when a pan is placed in the state without a pan, the panless state can be detected quickly. An object of the present invention is to provide an induction heating cooker that can cancel heating and return to heating.

In order to achieve the above object, an induction heating cooker according to the present invention includes a top plate formed of a material that transmits infrared rays, and a heating coil that induction-heats a pan placed at a predetermined position on the top plate. And an inverter circuit that supplies a high-frequency current to the heating coil, an infrared sensor that detects infrared rays that are radiated from the bottom surface of the pan and transmitted through the top plate, and an output of the infrared sensor is equal to or greater than a first predetermined value. A control unit for controlling the output of the inverter circuit so as to stop the heating of the pan by the heating coil, and a display unit for displaying a set thermal power and a heating state, and heating the pan by the heating coil After the start, when the output of the infrared sensor becomes equal to or higher than a second predetermined value corresponding to a temperature higher than the first predetermined value, the control unit detects the predetermined position. Pot stops the heating of the heating coil is determined that there is no, the display unit is characterized in that an indication that there is no pot.

  As a result, when there is no pan at the position corresponding to the heating coil, or when the pan is moved greatly during heating, sunlight or illumination light enters the infrared sensor directly, and the detection output of the infrared sensor is By determining that there is no pan at a predetermined position when a value exceeding the output range at the time of normal temperature detection is reached, it is possible to quickly detect that there is no pan.

  The induction heating cooker of the present invention can quickly detect that there is no pan at the corresponding position above the heating coil, reduce the load on the electronic components, and when the small-diameter pan is out of pan, etc. Even when heating is possible, even if the infrared sensor cannot properly detect it, it stops heating and informs the user that there is no pan, and prompts the user to reposition the pan. The inverter does not oscillate afterwards, and it is possible to suppress the consumption of wasted power, and even if small metal objects are placed on the heating coil, they can be prevented from being heated to a high temperature. An induction heating cooker that is safe and easy to use can be provided.

  Moreover, when a pan is placed in a state without a pan, the detection of the state without a pan can be quickly canceled and the heating can be resumed.

Schematic of the upper surface of the induction heating cooker in Embodiment 1 of the present invention. No pan detection operation and display flowchart of induction heating cooker in Embodiment 1 of the present invention

  The first invention is a top plate formed of a material that transmits infrared rays, a heating coil that induction-heats a pan placed at a predetermined position on the top plate, and a high-frequency current is supplied to the heating coil. An inverter circuit, an infrared sensor that detects infrared rays radiated from the bottom surface of the pan and transmitted through the top plate, and heating of the pan by the heating coil is stopped when the output of the infrared sensor exceeds a first predetermined value. And a control unit for controlling the output of the inverter circuit, and a display unit for displaying a set thermal power and a heating state, and after starting heating the pan by the heating coil, the output of the infrared sensor is the When the temperature exceeds a second predetermined value corresponding to a temperature higher than the first predetermined value, the control unit determines that there is no pan at the predetermined position and adds the heating coil. Is stopped, the display unit is an induction heating cooker which is configured to a display indicating that there is no pot. Thereby, when the bottom surface temperature of the pan is equal to or higher than the first predetermined value and heating is stopped to prevent overheating, or when heating is intermittently performed at low heating power, etc., the heating off period is However, when the pan is removed from a predetermined position on the top plate or when the pan is greatly displaced, the infrared sensor can directly detect the state of no pan by quickly detecting the light of sunlight or lighting, Since the inverter does not oscillate, it is possible to reduce the load applied to the electronic component and to suppress the consumption of wasted power. Also, even if the small diameter pan is out of pan, it can be heated, but even if it is not properly detected by the infrared sensor, it stops heating and informs the user that there is no pan. Can be repositioned. Furthermore, even when small metal objects such as knives and forks are placed on the heating coil, they can be prevented from being heated to a high temperature.

2nd invention has a pan detection circuit which detects whether a pan exists on the said heating coil by the characteristic of the output of the said inverter circuit especially in 1st invention, The said pan detection circuit does not have a pan When the control unit detects that the pan is not on the display unit and stops heating by the heating coil, the inverter circuit is intermittently oscillated so that the pan is on the heating coil. When the output of the infrared sensor becomes equal to or higher than the second predetermined value, heating by the heating coil is stopped regardless of the output of the pan detection circuit, and the inverter is detected. The circuit is configured not to intermittently oscillate, and the display unit displays the same display as when the pan detection circuit detects that there is no pan. This ensures that no pan is detected by the pan detection circuit based on the output characteristics of the inverter circuit when the inverter circuit is oscillated even when the infrared sensor cannot detect the absence of pan due to the usage environment, such as when used in a dark room. If the infrared sensor detects the absence of pan, the intermittent oscillation can be stopped so that unnecessary power is not consumed. By using the same display at the time of detection, the user can recognize concisely and clearly only that the pan is not placed in the predetermined position, regardless of which method the panless state is detected. it can.

  According to a third aspect of the invention, in the first or second aspect of the invention, when the output of the infrared sensor becomes equal to or higher than a third predetermined value corresponding to a temperature higher than the first predetermined value, the control unit is There is provided a hard stop section for stopping the heating coil by forcibly stopping the drive signal of the inverter without intervention. As a result, even if an unexpected situation occurs, such as when the microcomputer that constitutes the control unit operates abnormally due to a latch, etc., and continues to output a heating signal, heating is reliably stopped when there is no pan and the pan is not placed. It is possible to prevent the heating operation from continuing, and it is possible to prevent a dangerous state such as heating of small metal objects from occurring.

  In a fourth aspect of the invention, in particular, in any one of the first to third aspects of the invention, the control unit determines the absence of a pan based on the output of the infrared sensor until the first predetermined time elapses. When the output of the sensor falls below a fourth predetermined value corresponding to a temperature lower than the second predetermined value, the operation of the inverter is started to resume heating of the heating coil, and the first predetermined time When the output of the infrared sensor does not fall below the fourth predetermined value until the time elapses, the display unit turns off the panless display and returns to the initial state. Thereby, even when a pan is placed while the infrared sensor is not detecting the pan, the infrared sensor can quickly determine the presence of the pan and return the heating, so that it is easy to use and the cooking performance is improved. In addition, when no pan is placed, it is possible to prevent wasteful power consumption by turning off the panless display after a predetermined time has elapsed.

  In a fifth aspect of the invention, in particular, in any one of the first to fourth aspects of the invention, the control unit determines that there is no pan at the predetermined position, and displays that the display unit has no pan. This is when the output of the infrared sensor is equal to or greater than the second predetermined value and the second predetermined time has elapsed. As a result, when the output of the infrared sensor temporarily rises due to noise, light incident when the pan is shaken, etc., the display unit can be prevented from displaying no pan, and flickering of the display can be prevented.

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

(Embodiment 1)
FIG. 1 is a schematic view of the upper surface of the induction heating cooker according to the first embodiment of the present invention. As shown in FIG. 1, the top plate 1 is arrange | positioned on the apparatus upper surface so that a to-be-heated object can be mounted. A heating coil 2 is provided below the top plate 1. An infrared sensor 3 that detects the temperature of the pan bottom of the pan placed on the heating coil 2 is arranged slightly in front of the center of the heating coil 2, and a control unit (not shown) corresponds to the set temperature set by the user. In the temperature adjustment mode that operates so as to be the temperature of the heated object, the output of the heating coil 2 is adjusted so that the output of the infrared sensor 3 becomes a value corresponding to the set temperature, and is set by the user. In the heating mode in which the object to be heated is heated with the set heating power, when the temperature of the object to be heated rises and the output of the infrared sensor 3 becomes higher than the first predetermined value, the output of the heating coil 2 is reduced to prevent overheating. Or operate to stop heating. Here, the infrared sensor 3 is arranged slightly in front of the heating coil 2, but the arrangement location is not limited as long as the temperature of the pan bottom of the pot on the heating coil 2 can be detected. A plurality of infrared sensors 3 may be arranged for one heating coil 2. On the front side (user side) of the top plate 1 is an operation including a power switch 4 that turns on and off the power supply to the machine body, a display unit 5 that displays a heating state corresponding to each of the plurality of heating coils 2, and a heating start key. Part 6 is provided.

  About the induction heating cooking appliance comprised as mentioned above, the operation | movement is demonstrated using FIG.

  FIG. 2 is a flowchart of the panless detection operation and display, and shows the operation from the initial mode of STEP 01 (heating stop, no display) that is in a state after the power is turned on. When the heating start key is operated in STEP02, the process proceeds to STEP03, enters the heating mode, operates the inverter, and starts heating. At this time, the display unit displays that the heating is being performed, for example, by lighting the set thermal power. Next, in STEP 04, it is determined whether or not the output of the infrared sensor 3 is greater than or equal to a second predetermined value. Here, the second predetermined value is a value higher than the first predetermined value corresponding to the temperature at which the heating power in the temperature adjustment mode is set to the maximum temperature or the heating power in the heating mode is reduced or stopped. Then, in a normal use state in which an object to be heated such as a pan is heated, it does not exceed the second predetermined value, but the infrared sensor 3 detects sunlight or light of illumination, and the output is the second predetermined value. When it is determined as above, it is determined that there is no pan and the process proceeds to STEP08. On the other hand, if the output of the infrared sensor 3 is less than the second predetermined value, the process proceeds to STEP 05. In STEP 05, it is determined whether the output of the infrared sensor 3 is equal to or higher than the first predetermined value. If this is the case, the process proceeds to STEP 06 to stop heating and return to STEP 04, and if it is less than the first predetermined value, the process proceeds to STEP 07 to perform heating and return to STEP 04, whereby the temperature corresponding to the first predetermined value is reached. This prevents overheating of the pan.

  In STEP08, which has been determined that there is no pan in STEP04 and has shifted to, the operation of the inverter is stopped to stop heating, and the display unit 5 displays that there is no pan, for example, by flashing the set thermal power. Then, it progresses to STEP09 and it is judged whether there is no pan and it is judged whether the 1st predetermined time passed since heating was stopped. When the first predetermined time has not elapsed, the process proceeds to STEP 10 and it is determined whether or not the output of the infrared sensor 3 is equal to or smaller than a fourth predetermined value that is equal to or smaller than the second predetermined value. Here, the fourth predetermined value is an output value in a range obtained when the infrared sensor 3 does not detect sunlight or illumination light, and is set to a level (for example, 300 ° C.) that can prevent oil ignition and the like. It shall be. When it is determined that the output of the infrared sensor 3 is equal to or lower than the fourth predetermined value, it is determined that a pan is placed on the heating coil 2, and the process proceeds to STEP03 to resume heating. The display unit 5 displays that the heating is in progress. If not less than the fourth predetermined value, the process returns to STEP09. If the first predetermined time has elapsed in STEP 09, the process proceeds to STEP 01 and the initial mode is set.

Further, when the output of the infrared sensor 3 becomes equal to or higher than a third predetermined value corresponding to a temperature higher than the first predetermined value while having the above-described operation, the inverter of the inverter does not pass through a control unit constituted by a microcomputer or the like. A hardware stop unit (not shown) that stops the drive signal directly and forcibly is provided, and the output of the infrared sensor 3 has exceeded the third predetermined value regardless of the operation of the flowchart of FIG. Is detected, the drive signal of the inverter is forcibly fixed near the ground potential of the drive signal, and the operation of the inverter is stopped. As a result, even if the worst condition occurs in which the microcomputer constituting the control unit stops functioning due to external noise and the inverter drive signal continues to be output, It is possible to stop heating reliably with a circuit made up of discretes that are less prone to malfunction, and that the heating operation is continued without a pan placed, and for example, metal objects such as knives and forks are heated. It can be effectively prevented.

  Note that both the second predetermined value and the third predetermined value are values corresponding to a temperature higher than the first predetermined value, but the vertical relationship between the second predetermined value and the third predetermined value is as follows. This does not necessarily matter. However, forcibly stopping the drive signal of the inverter is a crisis-avoidance operation, and ideally the third condition because the control unit should be set to a condition that is rarer than the condition for normally stopping the inverter. The predetermined value should be a value corresponding to a temperature equal to or higher than the second predetermined value.

  With the above configuration, the infrared sensor 3 directly detects sunlight or illumination light when the pan is removed or greatly displaced during heating, even during intermittent oscillation due to operations such as the temperature control function. Can quickly detect that there is no pan, so the user can quickly be notified that there is no pan, and when the pan has been removed for a certain period of time, It is possible to prevent wasteful power consumption without delaying the time to transition, and after detecting no pan, it is not necessary to perform intermittent oscillation to detect the re-mounting of the pan, so inverter oscillation does not occur. While reducing the load concerning an electronic component, it can suppress that useless electric power is consumed. Furthermore, even when small metal objects such as knives and forks are placed on the heating coil, they can be prevented from being heated to a high temperature. Further, even when a pan is placed during detection of no pan, the infrared sensor 3 can quickly detect that the pan has been placed and return the heating to improve usability and improve cooking performance. In addition, when no pan is placed, it is possible to prevent unnecessary power consumption by turning off the panless display and setting the initial mode after a predetermined time has elapsed.

  In addition, it is judged whether the pan is on the heating coil 2 according to the output characteristics of the inverter circuit, and if it is judged that there is no pan, the pan detection circuit that intermittently oscillates the inverter circuit to detect the re-mounting of the pan It is further preferable that the display unit has the same panless display when the infrared sensor 3 determines that the pan is not present and when the pan detection circuit detects that the pan is absent. Thereby, for example, when used in a dark room, even when the infrared sensor 3 cannot detect the absence of a pan depending on the usage environment, the absence of a pan can be reliably detected. Since it is the same at the time of detection and at the time of detection by the pan detection circuit, it is possible for the user to take actions such as adjusting the position of the pan or replacing the pan in a situation where there is no pan without a sense of incongruity.

  Further, when the time during which the output of the infrared sensor 3 is equal to or greater than the second predetermined value continues for the second predetermined time, it is determined that there is no pan on the heating coil 2 and the operation of the inverter is stopped for heating. It is good also as a structure which stops and the display part 5 displays that there is no pan. Thereby, when the output of the infrared sensor 3 rises temporarily due to noise or the like, the absence of pan is not detected and the display unit 5 can be prevented from displaying no pan, and flickering of the display can be prevented.

  The induction heating cooker of the present invention can quickly detect that there is no pan above the heating coil, reduce the load applied to the electronic components, and suppress consumption of wasted power. It can be applied to all uses of cooking devices that use sensors.

DESCRIPTION OF SYMBOLS 1 Top plate 2 Heating coil 3 Infrared sensor 4 Power switch 5 Display part 6 Operation part

Claims (5)

A top plate formed of a material that transmits infrared rays, a heating coil that induction-heats a pan placed at a predetermined position on the top plate, an inverter circuit that supplies high-frequency current to the heating coil, An infrared sensor for detecting infrared radiation radiated from the bottom surface and transmitted through the top plate; and the inverter circuit configured to stop heating the pan by the heating coil when the output of the infrared sensor is equal to or higher than a first predetermined value. A control unit for controlling the output; and a display unit for displaying a set heating power and a heating state. After starting heating the pan by the heating coil, the output of the infrared sensor is more than the first predetermined value. When the temperature exceeds a second predetermined value corresponding to a high temperature, the control unit determines that there is no pan at the predetermined position, and stops heating the heating coil, Serial display section induction cooking device has a configuration that an indication that there is no pot. According to the output characteristics of the inverter circuit, it has a pan detection circuit that detects whether or not the pan is on the heating coil, and when the pan detection circuit detects that there is no pan, the control unit displays the pan on the display unit. After indicating that there is no pan and stopping heating by the heating coil, the inverter circuit is intermittently oscillated to detect whether the pan is on the heating coil or not by the pan detection circuit. When the output of the sensor is equal to or greater than the second predetermined value, the heating by the heating coil is stopped regardless of the output of the pan detection circuit so that the inverter circuit does not oscillate intermittently. The induction heating cooker according to claim 1, wherein the pan detection circuit is configured to display the same as when the pan detection circuit detects that there is no pan. When the output of the infrared sensor becomes equal to or higher than a third predetermined value corresponding to a temperature higher than the first predetermined value, the drive signal of the inverter is forcibly stopped without passing through the control unit. The induction heating cooker according to claim 1 or 2, further comprising a hard stop unit that stops heating of the heating coil. The control unit determines that there is no pan from the output of the infrared sensor, and the output of the infrared sensor corresponds to a temperature lower than the second predetermined value until the first predetermined time elapses. When the value falls below a predetermined value, the operation of the inverter is started to resume heating of the heating coil, and the output of the infrared sensor does not fall below the fourth predetermined value until the first predetermined time elapses. The induction heating cooker according to any one of claims 1 to 3, wherein the display unit is configured to turn off the panless display and return to the initial state. The control unit determines that there is no pan at the predetermined position and displays the display unit indicating that there is no pan when the output of the infrared sensor remains above the second predetermined value. The induction heating cooker according to any one of claims 1 to 4, which is a time when a predetermined time of 2 or more has elapsed.