Induction heating device

• US 6,812,440 B2
• Filed: 05/17/2004
• Issued: 11/02/2004
• Est. Priority Date: 11/21/2001
• Status: Expired due to Term

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Fujita, Atsushi, Fujii, Yuji, Kataoka, Akira, Miyauchi, Takahiro, Niiyama, Koji, Hirota, Izuo
• Primary Examiner(s): Leung, Philip H.
• Application Number:
  US10/483,791
• Publication Number:
  US 20040188426A1
• Time in Patent Office: 169 Days
• Field of Search: 219/620-627, 219/661-668, 219/518, 993/25, 99D/IG.14, 363/74, 363/95
• US Class Current: 219/626
• CPC Class Codes: H05B 6/04 Sources of current
• CPC Class Codes: H05B 6/062 for cooking plates or the like

Abstract

An induction heating device prevents an object to be heated from being displaced and buoyed from a mounting surface due to an mutual action of repulsive forces between the object to be heated and an induction heating coil. The induction heating device includes a source-current detector for detecting a source current input to a high-frequency inverter including the induction heating coil and an inverter circuit, a source-current change detector for measuring a change against time of a magnitude of the source current to detect a displacement and buoying of the object to be heated, such as a cooking pot, and a change examining unit. The controller controls an output of the high-frequency inverter in response to a detection result of the change examining unit. The induction heating device prevents the cooking pot from being displaced and buoyed even if the pot is not touched by a user at startup of heating or during the heating operation, and is inexpensive and safe.

Claims

1. An induction heating device comprising:

an induction heating coil for generating a high frequency magnetic field to heat an object;

an inverter for supplying a high frequency current to the induction heating coil;

an output detector for detecting an magnitude of an output of the inverter by detecting a power or a source current input to the inverter;

a displacement detector for measuring a change against lapse of time of the magnitude of the output of the inverter detected by the output detector and for detecting a displacement of the object based on the measured change; and

a controller for controlling the output of the inverter in response to a detection result of the displacement detector.

2. The induction heating device according to claim 1, wherein the displacement detector detects a displacement of the object based on the change against lapse of time of the magnitude of the output of the inverter before the output of the inverter shifts to a stable level from a level at a startup lower than the stable level.

3. The induction heating device according to claim 1, wherein the displacement detector detects a displacement of the object based on the change against lapse of time of the magnitude of the output of the inverter while the output is at a stable level.

4. An induction heating device comprising:

an induction heating coil for generating a high frequency magnetic field to heat an object;

an inverter for supplying a high frequency current to the induction heating coil;

an output detector for detecting a magnitude of an output of the inverter by detecting a peak or an average of a high frequency current or voltage produced by the inverter;

a displacement detector for measuring a change against lapse of time of the magnitude of the output of the inverter detected by the output detector and for detecting a displacement of the object based on the measured change; and

a controller for controlling the output of the inverter in response to a detection result of the displacement detector.

5. The induction heating device according to claim 4, wherein the displacement detector detects a displacement of the object based on the change against lapse of time of the magnitude of the output of the inverter before the output of the inverter shifts to a stable level from a level at a startup lower than the stable level.

6. The induction heating device according to claim 4, wherein the displacement detector detects a displacement of the object based on the change against lapse of time of the magnitude of the output of the inverter while the output is at a stable level.