Error correction for optical detector in glass-ceramic cooktop appliances

• US 20040099652A1
• Filed: 11/27/2002
• Published: 05/27/2004
• Est. Priority Date: 11/27/2002
• Status: Active Grant

• Current Assignee: Haier US Appliance Solutions, Inc. DBA GE Appliances (Haier Group Company)
• Original Assignee: General Electric Company
• Inventors: Berkcan, Ertugrul, Saulnier, Emilie Thorbjorg
• Granted Patent: US 6,864,465 B2
• Time in Patent Office: Days
• US Class Current: 219/448.11
• CPC Class Codes: H05B 3/746 Protection, e.g. overheat cutoff, hot plate indicator

Abstract

A sensor assembly for a glass-ceramic cooktop appliance having at least one burner assembly disposed under a glass-ceramic plate. The sensor assembly includes an optical detector arranged to receive radiation from the glass-ceramic plate and produce an output signal corresponding to a cooktop related property of the glass-ceramic plate. A controller is provided to receive the output signal from the optical detector. The controller includes means for making a correction to said output signal for corruptive flux incident on the optical detector.

Claims

1. A sensor assembly for a glass-ceramic cooktop appliance having at least one burner assembly disposed under a glass-ceramic plate, said sensor assembly comprising:

an optical detector, said optical detector being arranged to receive radiation from said glass-ceramic plate and produce an output signal corresponding to a cooktop related property of said glass-ceramic plate; and

a controller receiving said output signal from said optical detector, said controller including means for making a correction to said output signal for corruptive flux incident on said optical detector.

2. The sensor assembly of claim 1 wherein said cooktop related property is temperature.

3. The sensor assembly of claim 1 wherein said means for making a correction monitors the power level of said burner assembly and corrects said output signal based on a scale factor that corresponds to the power level .

4. The sensor assembly of claim 1 wherein said means for making a correction monitors the current level of said burner assembly and corrects said output signal based on a scale factor that corresponds to the current level.

5. The sensor assembly of claim 1 wherein said means for making a correction monitors the voltage level of said burner assembly and corrects said output signal based on a scale factor that corresponds to the voltage level.

6. The sensor assembly of claim 1 wherein said optical detector includes first and second detector elements, said first detector element producing said first-mentioned output signal and said second detector element producing a second output signal that is fed to said controller, said means for making a correction determining an error signal from said second output signal and subtracting said error signal from said first-mentioned output signal.

7. The sensor assembly of claim 1 wherein said means for making a correction subtracts a DC offset correction from said output signal.

8. The sensor assembly of claim 1 wherein said means for making a correction subtracts a predetermined percentage of said output signal from said output signal.

9. The sensor assembly of claim 8 wherein said predetermined percentage is in the range of about 5-15 percent.

10. The sensor assembly of claim 1 wherein said means for making a correction establishes and uses a power estimate of said corruptive flux to correct said output signal.

11. The sensor assembly of claim 10 wherein said power estimate is based on the relationship:

T_cir=α

₁+α

₂I

where T_cir is the effective color temperature of said burner assembly, a₁ and a₂ are constants, and I is the current through said burner assembly.

12. The sensor assembly of claim 10 wherein said power estimate is based on the relationship:

13. The sensor assembly of claim 10 wherein said power estimate is based on the relationship:

14. The sensor assembly of claim 1 further comprising a filter disposed between said optical detector and said glass-ceramic plate, said filter blocking flux in the spectrum in which corruptive flux is most prevalent.

15. The sensor assembly of claim 1 wherein the underside of said glass-ceramic plate is roughened.

16. The sensor assembly of claim 1 wherein the underside of said glass-ceramic plate is provided with an anti-reflective coating.

17. A method for sensing cooktop related properties in a glass-ceramic cooktop appliance having at least one burner assembly disposed under a glass-ceramic plate and an optical detector arranged to receive radiation from said glass-ceramic plate and produce an output signal corresponding to a cooktop related property of said glass-ceramic plate, said method comprising:

monitoring said output signal; and

making a correction to said output signal for corruptive flux incident on said optical detector.

18. The method of claim 17 wherein said correction is made by monitoring the power level of said burner assembly and correcting said output signal based on a scale factor that corresponds to the power level.

19. The method of claim 17 wherein said correction is made by monitoring the current level of said burner assembly and correcting said output signal based on a scale factor that corresponds to the current level.

20. The method of claim 17 wherein said correction is made by monitoring the voltage level of said burner assembly and correcting said output signal based on a scale factor that corresponds to the voltage level.

21. The method of claim 17 wherein said optical detector includes first and second detector elements, said first detector element producing said first-mentioned output signal and said second detector element producing a second output signal, and wherein said correction is made by determining an error signal from said second output signal and subtracting said error signal from said first-mentioned output signal.

22. The method of claim 17 wherein said correction is made by subtracting a DC offset correction from said output signal.

23. The method of claim 17 wherein said correction is made by subtracting a predetermined percentage of said output signal from said output signal.

24. The method of claim 23 wherein said predetermined percentage is in the range of about 5-15 percent.

25. The method of claim 17 wherein said correction is made by establishing and us power estimate of said corruptive flux.

26. The method of claim 25 wherein said power estimate is based on the relationship:

T_cir=α

₁+α

₂I

where T_cir is the effective color temperature of said burner assembly, a₁ and a₂ are constants, and I is the current through said burner assembly.

27. The method of claim 25 wherein said power estimate is based on the relationship:

28. The method of claim 25 wherein said power estimate is based on the relationship:

29. The method of claim 17 further comprising disposing a filter between said optical detector and said glass-ceramic plate, said filter blocking flux in the spectrum in which corruptive flux is most prevalent.

30. The method of claim 17 further comprising roughening the underside of said glass-ceramic plate.

31. The method of claim 17 further comprising providing an anti-reflective coating on the underside of said glass-ceramic plate.

32. A method for determining an error correction in a glass-ceramic cooktop appliance having at least one burner assembly disposed under a glass-ceramic plate and an optical detector arranged to receive radiation from said glass-ceramic plate and produce an output signal corresponding to a cooktop related property of said glass-ceramic plate, said method comprising:

obtaining a fit of said output signal against a reference temperature for a power off phase of said burner assembly;

applying said fit to construct an expected signal for a power on phase of said burner assembly; and

using the difference of said power off fit and said power on fit to obtain an error correction.

33. The method of claim 32 further comprising obtaining a map or a modeling of said error correction as a function of the current through said burner assembly.

34. The method of claim 32 further comprising obtaining a map or a modeling of said error correction as a function of the power to said burner assembly.

35. The method of claim 32 further comprising obtaining a map or a modeling of said error correction as a function of the voltage to said burner assembly.

36. The method of claim 32 further comprising calibrating said error correction in terms of the ratio of said error correction to said output signal.