Induction heating cooker

Patent metadata

Field	Value
Publication number	US-9769883-B2
Application number	US-201013256154-A
Country	US
Kind code	B2
Filing date	Mar 11, 2010
Priority date	Mar 19, 2009
Publication date	Sep 19, 2017
Grant date	Sep 19, 2017

Abstract

There is provided a placement position determining part that calculates a rising gradient of an output value of the infrared sensor every after passage of a first predetermined time and performs a placement position determining operation of determining that a placement position of a cooking vessel is improper when the rising gradient is smaller than a first threshold value, and the placement position determining part performs the placement position determining operation after a lapse of a second predetermined time from the start of heating, thereby accurately determining that the cooking vessel is improperly placed on a top plate and preventing overheating of the cooking vessel.

First claim

The invention claimed is:

1. An induction heating cooker comprising:
a top plate configured to carry a cooking vessel placed thereon;
a heating coil provided under the top plate and configured to inductively heat the cooking vessel;
an inverter circuit configured to supply a high-frequency current to the heating coil;
an infrared sensor configured to detect an infrared ray emitted from a bottom surface of the cooking vessel;
a heat-sensitive element in contact with a lower surface of the top plate for detecting a temperature of the cooking vessel;
a control part configured to compare a temperature detected by the heat-sensitive element to a control temperature value associated with the heat-sensitive element, which is set to a first temperature value, and to reduce an output of the inverter circuit or stop a heating operation when the temperature detected by the heat-sensitive element exceeds the control temperature value; and
a placement position determining part configured to:
repeatedly determine a temperature detected by the infrared sensor at a period equal to a first predetermined time to thereby periodically determine a rate of increase of an output value of the infrared sensor,
when after passage of a second predetermined time from the start of heating, the temperature detected by the infrared sensor is a) determined to be higher than a predetermined temperature value and b) the rate of increase of the output value of the infrared sensor is smaller than a first threshold value, determine that a placement position of the cooking vessel is improper,

wherein when the placement position determining part determines that the cooking vessel is improperly placed, the control part is further configured to set the control temperature value associated with the heat-sensitive element to a second temperature value lower than the first temperature value to thereby cause the heating operation to continue up until the second temperature value is detected by the heat-sensitive element and then stop.

2. The induction heating cooker according to claim 1 , wherein
the placement position determining part is configured to determine that the placement position of the cooking vessel is improper when the rate of increase is less than the first threshold value and when a rise value of detected temperature of the infrared sensor from the start of heating becomes larger than the first predetermined value before a lapse of the second predetermined time from the start of heating.

3. The induction heating cooker according to claim 1 , wherein
the placement position determining part is configured to determine that the placement position of the cooking vessel is improper when the rate of increase is less than the first threshold value and when an increase in an output voltage of the infrared sensor from the start of heating becomes larger than a second predetermined value before a lapse of the second predetermined time from the start of heating.

4. The induction heating cooker according to claim 1 , wherein
the placement position determining part is configured to calculate a rate of increase of detected temperature of the infrared sensor by calculating a rise value of the detected temperature of the infrared sensor at a third predetermined time shorter than the second predetermined time.

5. The induction heating cooker according to claim 1 , wherein when the placement position part calculates a rate of increase greater than or equal to the predetermined temperature value, the control temperature value is set to a third temperature value that is higher than the first temperature value to thereby cause the heating operation to continue up until the third temperature value is detected by the heat-sensitive element and then stop.

6. The induction heating cooker according to claim 1 , wherein
the control part is configured to reduce the output of the inverter circuit or stop the heating operation when the placement position determining part determines that the placement position of the cooking vessel is improper.

7. The induction heating cooker according to claim 1 , wherein
the placement position determining part is configured to calculate an increase gradient of the rate of increase every after passage of a fourth predetermined time and determines that the placement position of the cooking vessel is improper only when the increase gradient is smaller than a second threshold of negative value.

8. The induction heating cooker according to claim 7 , wherein
the placement position determining part is configured to calculate a value of increase in the rate of increase at a fifth predetermined time every after passage of the fourth predetermined time.

9. The induction heating cooker according to claim 1 , wherein
the placement position determining part is configured to determine that the placement position of the cooking vessel is improper only when the rate of increase continues to remain smaller than the first threshold value for a time period longer than a sixth predetermined time.

10. The induction heating cooker according to claim 2 , wherein
the placement position determining part is configured to determine that the placement position of the cooking vessel is improper when the rate of increase is less than the first threshold value and when the rise value of the detected temperature of the infrared sensor from the start of heating continues to be larger than the first predetermined value for a time period longer than a seventh predetermined time.

11. The induction heating cooker according to claim 3 , wherein
the placement position determining part is configured to determine that the placement position of the cooking vessel is improper when the rate of increase is less than the first threshold value and when the increase in the output voltage of the infrared sensor from the start of heating continues to be larger than the second predetermined value for a time period longer than an eighth predetermined time.

12. The induction heating cooker according to claim 7 , wherein
the placement position determining part is configured to determine that the placement position of the cooking vessel is improper only when the increase gradient of the rate of increase continues to remain smaller than the second threshold value for a time period longer than a ninth predetermined time.

13. The induction heating cooker according to claim 1 , further comprising an informing part for issuing a warning, wherein
the control part causes the informing part to issue the warning when the placement position determining part determines that the placement position of the cooking vessel is improper.

14. An induction heating cooker comprising:
a top plate configured to carry a cooking vessel placed thereon;
a heating coil provided under the top plate and configured to inductively heat the cooking vessel;
an inverter circuit configured to supply a high-frequency current to the heating coil;
an infrared sensor configured to detect an infrared ray emitted from a bottom surface of the cooking vessel;
a heat-sensitive element in contact with a lower surface of the top plate for detecting a temperature of the cooking vessel;
a control part configured to compare a temperature detected by the heat-sensitive element to a control temperature value associated with the heat-sensitive element that is set to a first temperature value and to reduce an output of the inverter circuit or stop a heating operation when the temperature detected by the heat-sensitive element exceeds the control temperature value; and
a placement position determining part configured to periodically c

Assignees

• Hashimoto Takuya
• Watanabe Kenji
• Noguchi Shintaro
• Ogata Taizo
• Panasonic Ip Man Co Ltd

Inventors

• Hashimoto Takuya
• Watanabe Kenji
• Noguchi Shintaro
• Ogata Taizo

Classifications

• H05B6/062 Primary

  for cooking plates or the like · CPC title

• H05B2213/07

  Heating plates with temperature control means · CPC title

• H05B2213/04

  Heating plates with overheat protection means · CPC title

• H05B6/1209

  induction cooking plates or the like and devices to be used in combination with them · CPC title