US3883719A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Glass-ceramic cooktop with film heaters
Assignee: General Electric Co
•
Filing: 1974-05-10
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Granted: 1975-05-13
•
Expires: 1994-05-10
Abstract
Abstract A glass-ceramic cooktop with a plurality of metallic film heaters of circular pattern bonded to the underside thereof. Each turn of the film heater has a generally uniform electrical resistance per unit of length throughout its length and is shown of constant width. The resistance per unit of length of each turn increases from each turn to the next from the centermost turn of the circular pattern to the outermost turn so the widest turn is at the center, and each turn decreases in width from the centermost turn to the outermost turn. The spacing between turns is minimal and substantially uniform throughout. The film heater has a pair of adjacent terminal sections of relatively low resistance per unit area to reduce the temperature of the portion sections. the glass-ceramic plate in the vicinity of the terminal section.
Inventors
- 👤 Bohdan Hurko
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 14:27
CPC Classifications
H; H05; H05B; H05B3/00; H05B3/68; H05B3/74; H05B3/748; H05B2203/00; H05B2203/013; H05B2203/017
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
136 words
A solid plate surface heating unit comprising a flat plate having an electrical film heater in winding strip form of generally uniform thickness bonded to the underside thereof, the resistance per unit area of the heated portion of the film heater varying in increasing proportion to the distance of the given area from an imaginary center line of the film heater pattern to give a biased heat distribution toward the outside of the film heater pattern so that the temperature distribution across the top surface of the solid plate is substantially uniform, the resistance per unit area at a given distance from the center bEing substantially constant, while the resistance per unit area varies in steps on an ascending curve as the distance of a particular area increases from the center of the film heater pattern.
Claim 2
Dependent Claim
136 words
A solid plate surface heating unit comprising a flat plate having an electrical film heater in winding strip form of generally uniform thickness bonded to the underside thereof, the resistance per unit area of the heated portion of the film heater varying in increasing proportion to the distance of the given area from an imaginary center line of the film heater pattern to give a biased heat distribution toward the outside of the film heater pattern so that the temperature distribution across the top surface of the solid plate is substantially uniform, the resistance per unit area at a given distance from the center bEing substantially constant, while the resistance per unit area varies in steps on an ascending curve as the distance of a particular area increases from the center of the film heater pattern.
Claim 3
Dependent Claim
23 words
A solid plate surface heating unit as recited in claim 1 wherein the said film heater strip is wound in a circular pattern.
Claim 4
Dependent Claim
23 words
A solid plate surface heating unit as recited in claim 1 wherein the said film heater strip is wound in a spiral pattern.
Claim 5
Dependent Claim
57 words
A solid plate surface heating unit as recited in claim 3 wherein the said film heater strip has terminal portions outside the main heated area of the film heater, said terminal portions being of relatively low resistance per unit area so as to obtain a relatively low temperature at the terminal portions of the film heater strip.
Claim 6
Dependent Claim
74 words
A solid plate surface heating unit as recited in claim 2 wherein the said film heater strip has a pattern with a plurality of adjacent turns that are spaced apart a minimal distance that is substantially uniform throughout so that the film heater strip substantially covers a maximum area of the solid plate within a given area so as to obtain the lowest temperatures of the film heater strip for a given power rating.
Claim 7
Dependent Claim
37 words
A solid plate surface heating unit as recited in claim 3 wherein each individual turn of the spiral film heater strip is of generally uniform electrical resistance per unit area throughout the length of each individual turn.
Claim 8
Dependent Claim
39 words
A solid plate suface heating unit as recited in claim 6 wherein the resistance per unit area of each turn increases from one turn to the next from the centermost turn of the spiral pattern to the outermost turn.
Claim 9
Dependent Claim
44 words
A solid plate surface heating unit as recited in claim 7 wherein each individual turn of the spiral film heater strip is of substantially uniform width throughout, while the width of the turns decreases in steps from the centermost turn to the outermost turn.
Claim 10
Dependent Claim
83 words
A solid plate surface heating unit as recited in claim 4 wherein the said spiral film heater strip is a double spiral pattern which is doubled back on itself adjacent the center of the spiral pattern, the film heater strip terminating in an adjacent pair of elongated terminal sections of relatively low resistance per unit area compared to the main heated portion of the film heater pattern so that the electrical terminations are made remote from the heated portion of the film heater.
Claim 11
Dependent Claim
48 words
A solid plate surface heating unit as recited in claim 9 wherein the said solid plate is a high resistivity glass-ceramic plate, and the said film heater is of multilayers of noble metals such as platinum and gold, and the said terminal sections include a layer of silver.
Claim 12
Dependent Claim
60 words
A solid plate surface heating unit as recited in claim 9 wherein the said solid plate is a metallic plate having a high resistivity porcelain enamel layer interposed between the film heater and the metallic plate, the said film heater comprising multi-layers of noble metals such as platinum and gold, and the said terminal sections include a layer of silver.
Claim 13
Dependent Claim
35 words
A solid plate surface heating unit as recited in claim 2 wherein the said circular pattern of the film heater strip is a folded concentric circular pattern having an adjacent pair of cold terminal sections.
Claim 14
Dependent Claim
45 words
A solid plate surface heating unit as recited in claim 3 wherein the said spiral pattern is a single spiral having one terminal section located adjacent the center of the film heater pattern and a second terminal located adjacent the outermost turn of the pattern.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-05-12 | 1978-11-11 | 1979-05-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-05-12 | 1982-11-11 | 1983-05-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-05-12 | 1986-11-11 | 1987-05-13 | $7700.00 | Window Closed / Lapsed |