INDUCTION COOKING APPLIANCE INCLUDING TEMPERATURE SENSING OF INDUCTIVELY HEATED COOKING VESSEL BY "MODULATED" LIGHT

• US 3,719,789 A
• Filed: 12/29/1971
• Issued: 03/06/1973
• Est. Priority Date: 12/29/1971
• Status: Expired due to Term

• Current Assignee: John D. Harnden Jr
• Original Assignee: John D. Harnden Jr
• Inventors: Harnden, John D. Jr.
• Primary Examiner(s): Staubly, R. F.
• Assistant Examiner(s): Reynolds, B. A.
• Application Number:
  US05/213,352
• Time in Patent Office: 433 Days
• Field of Search: 219/10.49,10.75,10.77,10.79,502 356/43,45,48 73/355 350/16LC
• US Class Current: 219/627
• CPC Class Codes: F24C 3/126 on ranges
• CPC Class Codes: H05B 2213/07 Heating plates with temperature control means
• CPC Class Codes: H05B 6/062 for cooking plates or the like

Abstract

Herein disclosed is an induction cooking range having a counter on which there is supported a cooking vessel to be inductively heated by an induction coil having a central aperture; the induction coil being located below the counter. The cooling vessel, or utensil, has at least on portion thereof coated or covered with a material which changes at least one optical property thereof in response to temperature changes. The coated portion of the vessel which rests on the counter covers a passage provided in the counter; said passage being axially aligned, or in register, with the central aperture of the coil. The range includes a temperature sensing unit comprising an LED for directing monochromatic light through the central aperture and passage onto the vessel'"'"''"'"'s coating. The temperature sensing unit also includes a photodetector for detecting the light reflected from the coating whereby the temperature of the vessel is determinable. In another embodiment the counter is made of light transmitting material and the aforesaid passage is not required; the directed and reflected light passing through the counter.

Claims

1. An induction cooking appliance, for heating a cooking vessel having at least one portion thereof in which electric current may be induced to heat said one portion and to vary at least one optical parameter of said portion in response to the temperature thereof, comprising:

vessel suPporting means in which no substantial heating current is induced when said supporting means is subjected to a changing magnetic field, said supporting means having a surface on which said vessel is supportable and a passage extending through said supporting means and defining at said surface a first opening and also defining a second opening at another end of said passage, at least a part of said one portion of said vessel being proximate said first opening when said vessel is supported on said surface so that from said part there extends a light propagation path which is comprised of said first opening, said passage, and said second opening;

an induction coil energizable for generating a changing magnetic field in said one portion of the supported vessel whereby heating current is induced in said one portion and said one optical parameter is varied;

means for energizing said coil with electric power of at least ultrasonic frequency; and

means, coupled with said light propagation path, for detecting temperature-correlated changes in said optical parameter.

2. The appliance according to claim 1 further comprising signal means, coupled with said means for detecting temperature correlated changes, for generating a signal representative of the temperature of said one portion corresponding to the change in the optical parameter thereof.

3. The appliance according to claim 2 wherein said means for detecting temperature correlated changes includes a light source and light responsive means, said light source being arranged to direct light through said propagation path onto said part of said one portion whereat said part reflects said directed light as modulated light which includes information as to the temperature of said part of said one portion corresponding to a change in said optical parameter, said light responsive means receiving said modulated light, and, in turn, modulating said signal means.

4. The appliance according to claim 3 wherein said light source is comprised of light emitting diode.

5. The appliance according to claim 3 wherein said light source includes a lens for directing light from said light source through said propagation path and on to said part of said one portion of said vessel.

6. The appliance according to claim 3 wherein said light responsive means is comprised of a photodiode.

7. The appliance according to claim 3 wherein said light source emits monochromatic light.

8. The appliance according to claim 3 wherein said light source is comprised of a light emitting diode which emits monochromatic light and wherein said light responsive means is comprised of a photodiode.

9. The apparatus according to claim 8 wherein said optical parameter is color.

10. An induction cooking appliance, for heating a cooking vessel having at least one portion thereof in which electric current may be induced to heat said one portion and to vary at least one optical parameter of said portion in response to the temperature of said one portion, comprising:

vessel supporting means in which no substantial heating current is induced when said supporting means is subjected to a changing magnetic field, said supporting means having a surface on which said vessel is supportable, said supporting means being comprised of a material which transmits light;

an induction coil energizable for generating a changing magnetic field in said one portion of the supported vessel whereby heating current is induced in said one portion and said one optical parameter is varied;

means for energizing said coil with electric power of at least ultrasonic frequency; and

, means, optically coupled with said vessel supporting means, for detecting temperature-correlated changes in said optical paramater.

11. The appliance according to claim 10 further comprising:

signal means, coupled with said means for detecting temperature correlated changes, for generating a signal representative of the temperature of said one portion corresponding to the change in the optical parameter thereof.

12. The appliance according to claim 11 wherein said means for detecting temperature correlated changes includes a light source and light responsive means, said light source and light responsive means, said light source being arranged to direct light through said light transmitting vessel supporting means onto said one portion of said vessel whereat said one portion reflects said directed light as modulated light through said vessel supporting means, said modulated light including information as to the temperature of said one portion corresponding to a change in said optical parameter, said light responsive means receiving said modulated light, and, in turn, modulating said signal means.

13. The appliance according to claim 12 wherein said light source is comprised of a light emitting diode which emits monochromatic light and wherein said light responsive means is comprised of a photodiode.

14. The appliance according to claim 10 wherein said optical parameter is color.

15. An induction cooking appliance, for heating a cooking vessel having at least one portion thereof in which electric current may be induced to heat said one portion and to vary the color of said one portion in response to the temperature thereof, comprising:

a light transmitting counter in which no substantial heating current is induced when said counter is subjected to a changing magnetic field, said counter having an uninterrupted surface on which said vessel is supportable;

an induction coil energizable for generating a changing magnetic field in said one portion of said supported vessel whereby heating current is induced in said one portion and the color of said one portion is varied;

means for energizing said coil with electric power of at least ultrasonic frequency;

a light emitting diode emitting monochromatic light through said counter and onto said one portion of said vessel, said heated one portion of said vessel reflecting the monochromatic light directed thereat by said light emitting diode through said counter;

light responsive means for receiving the reflected light transmitted through said counter from said heated one portion; and

, signal means coupled with said light responsive means for generating a signal representative of the temperature of said one portion of said vessel corresponding to the color of said one portion.

16. In combination with a cooking vessel including at least one portion thereof in which electric current may be induced by a changing magnetic field to heat said one portion and to vary the temperature thereof, said vessel including a coating on said one portion which changes color in response to the temperature of said one portion, an induction cooking appliance comprising:

light-transmitting vessel supporting means in which no substantial heating current is induced when said supporting means is subjected to a changing magnetic field, said supporting means having a surface on which said vessel is supportable;

an induction coil energizable for generating a changing magnetic field in said one portion of the supported vessel whereby heating current is induced in said one portion and said coating changes color in response to the temperature of said one portion;

means for energizing said coil with electric power of at least ultrasonic frequency; and

, means, optically coupled with said light-transmitting supporting means, for detecting temperature-correlated color changes of said coating.

17. The combination according to claim 16 wherein said coating is comprised of liquid crystals which change the color of said coating in response to the temperature thereof.

18. The appliance according to claim 6 further comprising means for varying the color of the light emitted by said light emitting diode and wherein said optical parameter is color.