Electrical heating device

• US 4,626,664 A
• Filed: 09/26/1984
• Issued: 12/02/1986
• Est. Priority Date: 02/15/1984
• Status: Expired due to Fees

• Current Assignee: Calorique Limited
• Original Assignee: Flexwatt Corporation
• Inventors: Grise, Frederick G. J.
• Primary Examiner(s): Goldberg, E. A.
• Assistant Examiner(s): PRESTON, GERALD
• Application Number:
  US06/654,772
• Time in Patent Office: 797 Days
• Field of Search: 219/203, 219/211, 219/212, 219/217, 219/345, 219/464, 219/522, 219/528, 219/535, 219/539, 219/541, 219/543, 219/544, 219/553, 219/525, 219/542, 219/549, 338/22 R, 338/22 SD, 338/211, 338/212, 338/217
• US Class Current: 219/525
• CPC Class Codes: H05B 2203/013 Heaters using resistive films or coatings
• CPC Class Codes: H05B 2203/016 Heaters using particular connecting means
• CPC Class Codes: H05B 2203/032 Heaters specially adapted for heating by radiation heating
• CPC Class Codes: H05B 3/26 heating conductor mounted on insulating base for transparent areas H05B3/84, H05B3/86
• CPC Class Codes: H05B 3/56 Heating cables
• CPC Class Codes: H05B 3/565 flat cables

Abstract

An electrical heating device comprising a substrate having an upper insulating surface, a semi-conductor pattern carried on the insulating surface, and a pair of metallic conductors mounted in face-to-face engagement with said semi-conductor pattern. The semi-conductor pattern includes a pair of spaced connector portions and at least one heating portion extending between and electrically connected to each of said connector portions, the connector portions have a electrical conductivity greater than that of said heating portion, and each of the metallic conductors is in face-to-face engagement with a respective one of said connector portions and has an area that is less than that of said respective one of said connector portions and an area:perimeter ratio greater than D/20 wherein D is the major dimension of the respective conductor portion.

Claims

1. In an electrical heating device comprising

a generally flat substrate having an upper insulating surface,

a semi-conductor pattern carried by said upper surface of said substrate, and

a pair of generally flat metallic conductors mounted in a face-to-face engagement with said semi-conductor pattern,

that improvement wherein:

said semi-conductor pattern includes a pair of spaced connector portions and at least one heating portion extending between and electrically connected to each of said connector portions;

said connector portions have an electrical conductivity greater than that of said said heating portion; and

,

each of said metallic conductors is in face-to-face engagement with a respective one of said connector portions, and the surface thereof in such engagement has an area that is less than the area of the upper surface of said respective one of said connector portions, the area;

perimeter ratio of said surface of said conductor being about D/4 wherein D is the major dimension of said area of said conductor.

2. The heating device of claim 1 wherein an insulating layer overlyies said semi-conductor pattern and said conductors and sealing engages portions of said substrate that are free from said semi-conductor pattern.

3. The heating device of claim 1 including a wire electrically connected to each of said conductors, each such electrical connection being made by a connector engaging said wire and extending through a respective conductor.

4. The heating device of claim 1 wherein said heating portion includes areas having different conductivities (ohms per square).

5. The heating device of claim 1 wherein the minimum distance from said heating portion to a side edge of said heater is less than the width of either of said connection portions.

6. The heating device of claim 1 wherein said heating portion extends from one of said connection portions through a loop of at least 180°

to the other of said connection portions.

7. The heating device of claim 6 including two of said heating portions connected to generally opposite sides of said connection portions.

8. The heating device of claim 1 including two of said heating portions, each of said heating portions having substantially the same watt density.

9. The heating device of claim 1 wherein said heating portions are substantially identical and extend in generally opposite directions from said connection portions.

10. The heating device of claim 1 wherein each of said connecting portions are adjacent each other, and said heating portion extends from each of said connecting portions in a direction forming an angle of not less than about 90°

with a line extending directly from one of said connecting portions to the other of said connecting portions.

11. The heating device of claim 10 including at least two of said heating portions.

12. In an electrical heating device comprising

a generally flat substrate having an upper insulating surface,

a semi-conductor pattern carried by said upper surface of said substrate, and

a pair of metallic conductors mounted in face-to-face engagement with said semi-conductor pattern,

that improvement wherein:

said semi-conductor pattern includes generally U-shaped heating portions extending in opposite directions from and electrically connected to each of said conductors; and

each of said heating portions includes areas of different conductivities (ohms per square) connected electrically in series.

13. The heating device of claim 12 wherein each of heating portions includes a pair of parallel, spaced apart leg portions of a first conductivity and an intermediate portion of a second conductivity different from said first conductivity.

14. The heating device of claim 13 wherein said semi-conductor pattern includes a pair of spaced connector portions, each of said leg portions has one end thereof connected to a respective one of said connector portions, and the other end thereof connected to a said intermediate portion.

15. The heating device of claim 12 wherein said heating portions are substantially identical.

16. The heating device of claim 14 wherein said connecting portions are adjacent each other, and a said heating portion extends from each of said connecting portions in a direction forming an angle of not less than about 90°

with a line extending directly from one of said connecting portions to the other of said connecting portions.