Glass ceramic cooktop with infrared sensor

Patent metadata

Field	Value
Publication number	US-2017215231-A1
Application number	US-201715411745-A
Country	US
Kind code	A1
Filing date	Jan 20, 2017
Priority date	Jan 21, 2016
Publication date	Jul 27, 2017
Grant date	—

Abstract

A cooktop is provided that includes a glass ceramic cooking plate that exhibits enhanced mechanical strength and at the same time increased spectral transmittance in the infrared range. The glass ceramic cooking plate makes it possible to detect, through the glass ceramic cooking plate, the temperature of a piece of cookware placed thereon using an infrared sensor, and to perform an automated cooking process in response thereto.

First claim

What is claimed is:

1 . A cooktop, comprising:
a glass ceramic cooking plate with at least one cooking zone; at least one heater arranged below the glass ceramic cooking plate in a region of the cooking zone; at least one infrared sensor having a sensing area arranged so as to face the cooking zone through the glass ceramic cooking plate; electronics connected to the at least one infrared sensor, the electronics being configured to control a power output of the at least one heater based on an output signal of the at least one infrared sensor, and wherein the glass ceramic cooking plate is made of a lithium aluminosilicate glass ceramic containing a composition (in percent by weight) of:

Al 2 O 3
18-23,

Li 2 O
2.5-4.2,

SiO 2
60-69,

ZnO
0-2,

Na 2 O + K 2 O
0.2-1.5,

MgO
  0-1.5,

CaO + SrO + BaO
0-4,

B 2 O 3
0-2,

TiO 2
2.3-4.5,

ZrO 2
0.5-2,  

P 2 O 5
0-3,

SnO 2
  0-<0.6,

Sb 2 O 3
  0-1.5,

As 2 O 3
  0-1.5,

TiO 2 + ZrO 2 + SnO 2
3.8-6,  

preferably V 2 O 5
0.01-0.08,

Fe 2 O 3
0.008-0.3, 

wherein the glass ceramic cooking plate has a gradient layer at or towards a surface thereof and an underlying core,
wherein the glass ceramic cooking plate has keatite mixed crystals as a predominant crystal phase in the core and high-quartz mixed crystals as a predominant crystal phase in the gradient layer, and
wherein the keatite mixed crystals have a crystal phase content that exceeds 50% a total crystal phase content of the high-quartz mixed crystals and the keatite mixed crystals in a depth of 10 μm or more.

2 . The cooktop as claimed in claim 1 , wherein the composition further comprises coloring oxides up to a maximum amount of 1.0 wt %.

3 . The cooktop as claimed in claim 1 , wherein the glass ceramic cooking plate has a thickness in a range between 2.8 mm and 4.2 mm.

4 . The cooktop as claimed in claim 1 , wherein the glass ceramic cooking plate has a transmittance, normalized to a glass ceramic cooking plate of 4 mm thickness, selected from the group consisting of greater than 5% at a wavelength of 3000 nm, greater than 7% at a wavelength of 3000 nm, greater than 18% at a wavelength of 3200 nm, greater than 24% at a wavelength of 3200 nm, greater than 37% at a wavelength of 3400 nm, greater than 43% at a wavelength of 3400 nm, greater than 51% at a wavelength of 3600 nm, greater than 54% at a wavelength of 3600 nm, and any combinations thereof.

5 . The cooktop as claimed in claim 1 , wherein the infrared sensor has a spectral sensitivity in a range of wavelengths between 2800 nm and 4400 nm.

6 . The cooktop as claimed in claim 1 , wherein the electronics being configured to control the power output of the at least one heater based on an emission coefficient of a piece of cookware on the region of the cooking zone.

7 . The cooktop as claimed in claim 1 , further comprising a conductor configured to guide heat radiation of a piece of cookware on the region of the cooking zone to the infrared sensor.

8 . The cooktop as claimed in claim 1 , wherein the sensing area of the infrared sensor faces a bottom or a lateral surface of a piece of cookware on the region of the cooking zone.

9 . The cooktop as claimed in claim 1 , wherein the glass ceramic cooking plate has a smooth surface on both faces thereof.

10 . The cooktop as claimed in claim 1 , further comprising a heater arranged on the glass ceramic cooking plate, wherein the heater is selected from the group consisting of a radiation heater, a halogen heater, an induction heater, and an electrical resistance heater.

11 . The cooktop as claimed in claim 1 , wherein the infrared sensor and the electronics are designed for control starting at a temperature of a piece of cookware on the region of the cooking zone of at least 90° C.

12 . The cooktop as claimed in claim 1 , wherein the infrared sensor and the electronics are designed for control starting at a temperature of a piece of cookware on the region of the cooking zone of at least 70° C.

13 . The cooktop as claimed in claim 1 , wherein the electronics are further configured to control an electrical appliance arranged outside the cooktop based on the output signal of the infrared sensor.

14 . The cooktop as claimed in claim 13 , wherein the electrical appliance is an exhaust hood.

15 . The cooktop as claimed in claim 1 , wherein the glass ceramic cooking plate has a reduced thickness in some areas, and wherein the gradient layer is provided in and/or beyond the areas of reduced thickness.

16 . The cooktop as claimed in claim 1 , wherein the glass ceramic cooking plate is has a bend and/or a three-dimension deformation, and wherein the gradient layer is provided in and/or beyond the bend and/or the three-dimensional deformation.

17 . The cooktop as claimed in claim 1 , wherein the glass ceramic cooking plate has at least one opening, and wherein the gradient layer is provided so as to extend to an edge of the opening and/or so as to extend on a wall of the opening.

18 . The cooktop as claimed in claim 1 , comprising a maximum fraction of diffused light, normalized to a glass ceramic cooking plate of 4 mm thickness, selected from the group consisting of not more than 15% at a wavelength of 470 nm, not more than 12% at a wavelength of 470 nm, not more than 20% in a range of wavelengths from 400 nm to 500 nm, not more than 17% in a range of wavelengths from 400 nm to 500 nm, not more than 6% at a wavelength of 630 nm, not more than 5% at a wavelength of 630 nm, not more than 4% at a wavelength of 630 nm, and any combinations th

Assignees

• Schott Ag

Inventors

• Doerk Birgit
• Bockmeyer Matthias
• Zenker Thomas
• Weiss Evelin
• Ohl Gerold
• Taplan Martin
• Dudek Roland
• Backes Sasha

Classifications

• C03C3/097

  containing phosphorus, niobium or tantalum · CPC title

• H05B6/1209

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

• H05B3/744

  Lamps as heat source, i.e. heating elements with protective gas envelope, e.g. halogen lamps · CPC title

• C03C3/083 Primary

  containing aluminium oxide or an iron compound · CPC title

• H05B3/74

  Non-metallic plates {, e.g. vitroceramic, ceramic or glassceramic hobs, also including power or control circuits} · CPC title