Induction heat cooking device

1. An induction heat cooking device comprising:

a top plate made of a material through which an infrared light is transmitted;

a heating coil for receiving a high frequency current to heat a cooking container placed on the top plate by induction;

an inverter circuit for providing the high frequency current to the heating coil;

an operation unit including an operation mode setting unit for setting an operation mode of the inverter circuit;

an infrared sensor for detecting an infrared light that is emitted from a bottom surface of the cooking container and transmitted through the top plate;

a control unit for controlling an output of the inverter circuit, based on an output of the infrared sensor and a setting inputted to the operation unit; and

a notification unit,

wherein the operation mode includes a preheating heating mode for performing preheating before performing heating,

wherein when the operation mode is set to a preheating heating mode, the control unit starts operation in a preheating mode for heating the cooking container with a first heating output corresponding to the preheating heating mode, and wherein when an increment of an output value of the infrared sensor is more than a first predetermined increment since the heating starts with the first heating output, the control unit causes the notification unit to notify a user that the preheating is finished, and the operation mode is changed to a waiting mode for performing heating with a second heating output that is lower than the first heating output.

2. The induction heat cooking device according to claim 1 , wherein the operation mode is changed to the waiting mode when the increment of the output value of the infrared sensor with respect to a predetermined initial output value exceeds the first predetermined increment, instead of the increment of the output value of the infrared sensor since the heating starts with the first heating output, and wherein the predetermined initial output value is an output value of the infrared sensor that is obtained when the cooking container, having such a temperature that the gradient of increase in the output of the infrared sensor with respect to a change of temperature of the cooking container is equal to or less than a predetermined value, is placed on the top plate.

3. The induction heat cooking device according to claim 1 , wherein the infrared sensor is arranged at a position in the radius direction of a coiled wire of the heating coil.

4. The induction heat cooking device according to claim 1 , wherein the infrared sensor includes a photodiode made of silicon.

5. The induction heat cooking device according to claim 1 , wherein when the increment of the output value of the infrared sensor is equal to or more than a second predetermined increment in the waiting mode, the heating is performed with a third heating output that is smaller than the second heating output, or the heating is halted, and wherein when the increment of the output value of the infrared sensor is less than a third predetermined increment that is equal to or less than the second predetermined increment, the heating is performed with the second heating output.

6. The induction heat cooking device according to claim 5 ,

wherein the operation unit further includes a heating power setting unit with which a user gives an instruction for setting a heating power of the inverter circuit,

wherein when the user inputs an instruction for changing the setting of the heating power by means of the heating power setting unit in the waiting mode, the operation mode is changed to the heating mode for performing heating with a fourth heating output corresponding to the heating power instructed by the user,

wherein when the increment of the output value of the infrared sensor is more than a fourth predetermined increment in the heating mode, the heating is performed with a fifth heating output that is smaller than the fourth heating output, or the heating is halted,

and wherein when the increment of the output value of the infrared sensor is less than a fifth predetermined increment that is equal to or less than the fourth predetermined increment, the heating is performed with the fourth heating output.

7. The induction heat cooking device according to claim 6 , wherein when the fourth heating output is more than the second heating output, the fourth predetermined increment is set larger than the second predetermined increment.

8. The induction heat cooking device according to claim 6 , wherein when the fourth heating output is less than the second heating output, the fourth predetermined increment is set equal to the first predetermined increment.

9. The induction heat cooking device according to claim 1 , wherein the first predetermined increment is changeable.

10. The induction heat cooking device according to claim 9 further comprising:

an input current detection unit for detecting a magnitude of an input current provided from a power source; and

a heating coil current detection unit for detecting a magnitude of a heating coil current flowing in the heating coil,

wherein the control unit determines a material of the cooking container based on the detected magnitude of the input current and the detected magnitude of the heating coil current at the start of the preheating mode, and sets the first predetermined increment based on the determined material of the cooking container.

11. The induction heat cooking device according to claim 9 further comprising:

a buoyancy reduction plate arranged between the top plate and the heating coil; and

a temperature detection unit for detecting a temperature of the buoyancy reduction plate,

wherein the control unit sets the first predetermined increment based on the temperature of the buoyancy reduction plate that is detected by the temperature detection unit after the heating starts with the first heating output.

12. The induction heat cooking device according to claim 9 further comprising:

a buoyancy reduction plate arranged between the top plate and the heating coil;

a first temperature detection unit for detecting a temperature of the buoyancy reduction plate; and

a second temperature detection unit for detecting a temperature of the top plate,

wherein the control unit determines whether the bottom surface of the cooking container is warped or not based on a difference between the temperature detected by the first temperature detection unit and the temperature detected by the second temperature detection unit, and sets the first predetermined increment according to whether there is a warpage or not.

13. The induction heat cooking device according to claim 1 ,

wherein the control unit includes an input power integration unit for adding up an input power,

wherein when the increment of the output value of the infrared sensor since the start of the heating with the first heating output is not more than the first predetermined increment but the integration value of the input power since the start of the heating with the first heating output, that is added up by the input power integration unit, is more than a predetermined power integration value, the notification unit notifies the user that the preheating is finished, and the operation mode is changed to the waiting mode.

14. The induction heat cooking device according to claim 13 , wherein the predetermined power integration value is changeable.

15. The induction heat cooking device according to claim 14 further comprising:

an input current detection unit for detecting a magnitude of an input current provided from a power source; and

a heating coil current detection unit for detecting a magnitude of a heating coil current flowing in the heating coil,

wherein the control unit determines a material of the cooking container based on the detected magnitude of the input current and the detected magnitude of the heating coil current at the start of the preheating mode, and sets the predetermined power integration value based on the determined material of the cooking container.