Flexible heater device

• US 20030102296A1
• Filed: 09/13/2002
• Published: 06/05/2003
• Est. Priority Date: 01/25/1999
• Status: Active Grant

• Current Assignee: Illinois Tool Works Inc.
• Original Assignee: Illinois Tool Works Inc.
• Inventors: Storiz, Paul J., Starozhitsky, Michael, Varma, Tilak R., Nelson, James P., Bulgajewski, Edward
• Granted Patent: US 6,884,965 B2
• Time in Patent Office: Days
• US Class Current: 219/217
• CPC Class Codes: B60N 2/5685 Resistance
• CPC Class Codes: H05B 2203/006 using interdigitated electrodes
• CPC Class Codes: H05B 2203/011 Heaters using laterally extending conductive material as connecting means
• CPC Class Codes: H05B 2203/013 Heaters using resistive films or coatings
• CPC Class Codes: H05B 2203/017 Manufacturing methods or apparatus for heaters
• CPC Class Codes: H05B 2203/019 Heaters using heating elements having a negative temperature coefficient
• CPC Class Codes: H05B 2203/02 Heaters using heating elements having a positive temperature coefficient
• CPC Class Codes: H05B 2203/029 Heaters specially adapted for seat warmers
• CPC Class Codes: H05B 3/34 flexible, e.g. heating nets or webs
• CPC Class Codes: H05B 3/342 heaters used in textiles
• CPC Class Codes: H05B 3/347 woven fabrics

Abstract

The heating device includes a conductive layer which is positioned on an electrically insulative substrate. Preferably, the conductive layer is screen printed onto the substrate. The substrate is designed to limit elongation of the conductive layer, thereby improving the durability of the conductor and enabling the heating device to be used in flexible applications, such as automobile seats. The substrate can include at least one aperture passing therethough to further improve flexibility, fatigue resistance, and breathability of the heater. The conductive layer is configured to include a buss structure with a first buss ground inwardly adjacent from the periphery of the heating device and a first buss with serpentine paths extending from one edge of the heating device to another edge. The buss structure further includes a second buss with L-shaped portions positioned between the serpentine paths and the first buss ground. The second buss ground is located in a central location between the serpentine paths. A resistive or thermistor layer, preferably with a resistance which increases materially in response to increased temperature, is placed over the conductive layer.

Claims

1. A heating device for producing heat when connected to an electrical power source, including:

an electrically insulative substrate positioned beneath a flexible member;

a conductive layer screen printed on said substrate in a pattern thereby forming a buss structure, wherein said substrate is adapted to limit elongation of said conductive layer when said substrate is subjected to a flexing action so as to improve durability of the conductive layer; and

a resistive layer applied to said conductive layer, such that when an electrical power source is connected to said buss structure of the heating device, heat is generated.

2. The heating device of claim 1, wherein said substrate is a polyester film.

3. The heating device of claim 1, wherein said substrate is a dielectric film substrate.

4. The heating device of claim 1, wherein said resistive layer has an increasing resistance in response to an increasing temperature, thereby resulting in a self-regulating temperature characteristic.

5. The heating device of claim 1, wherein said substrate includes apertures formed therethrough.

6. The heating device of claim 1, further comprising a flame retardant material.

7. The heating device of claim 1, wherein the heating device is a seat heater for an automobile.

8. A heating device for producing heat when connected to an electrical power source, including:

an electrically insulative substrate having at least one aperture extending therethrough;

a conductive layer screen printed on said substrate in a pattern thereby forming a buss structure; and

a resistive layer applied to said conductive layer, such that when an electrical power source is connected to said buss structure of the heating device, heat is generated.

9. The heating device of claim 8, wherein said substrate is a dielectric film substrate.

10. The heating device of claim 8, wherein said resistive layer has an increasing resistance in response to an increasing temperature, thereby resulting in a self-regulating temperature characteristic.

11. The heating device of claim 8, further comprising a flame retardant material.

12. The heating device of claim 8, wherein the heating device is a seat heater for an automobile.

13. A heating device for producing heat when connected to an electrical power source, including:

a substrate;

a layer of resistive material;

a layer of conductive material forming a buss structure for providing electrical current to said layer of resistive material; and

said buss structure including a first buss ground which extends around a periphery of the heating device;

a first buss in electrical communication with said first buss ground, including at least two serpentine paths extending through an area bounded by said first buss ground;

a second buss ground positioned between said at least two serpentine paths; and

a second buss located between said first buss ground and said at least two serpentine paths.

14. The heating device of claim 13, wherein said at least two serpentine paths include alternating inwardly facing curved portions and outwardly facing curved portions.

15. The heating device of claim 14, wherein said second buss ground includes second buss ground extensions which extend into said inwardly facing curved portions of said at least two serpentine paths

16. The heating device of claim 15, wherein said second buss includes second buss extensions which extend into said outwardly facing curved portions of said at least two serpentine paths.

17. The heating device of claim 16, wherein said second buss ground extensions and said second buss extensions have circular portions defining apertures therein which pass through the heating device.

18. The heating device of claim 17, wherein said second buss includes a first L-shaped portion comprises a first shorter leg and a first longer leg and a second L-shaped portion comprising a second shorter leg and a second longer leg.

19. The heating device of claim 18, wherein said first shorter leg and said second shorter leg are colinear along a first edge of the heating device, a space being formed between said first shorter leg and said second shorter leg through which said at least two serpentine paths extend.

20. The heating device of claim 19, wherein said first longer leg extends along a second edge of the heating device and said second longer leg extends along a third edge of the heating device, wherein said first longer leg is parallel to said second longer leg.

21. The heating device of claim 20, wherein said first longer leg and said second longer leg are perpendicular to said first shorter leg and said second shorter leg.

22. The heating device of claim 21, wherein said second buss ground is parallel to said first longer leg and said second longer leg.

23. The heating device of claim 22, wherein said at least two serpentine paths include spur portions.

24. The heating device of claim 23, wherein said second buss ground extensions include spur portions.

25. The heating device of claim 24, wherein said second buss extensions include spur portions.

26. The heating device of claim 13, wherein resistance of said resistive layer increases with increasing temperature thereby providing a self-regulating temperature characteristic.

27. The heating device of claim 13, wherein said substrate is dielectric.

28. The heating device of claim 27, wherein said conductive layer is screen printed over said substrate.

29. The heating device of claim 28, wherein said conductive layer is formed from a material chosen from the group consisting of copper, gold, silver, aluminum, carbon, graphitic materials and a conductive polymer.

30. A method of assembling a heating device for use in an automobile seat, the method comprising the steps of:

providing an electrically insulative substrate;

screen printing a conductive layer onto the substrate, the substrate being adapted to limit elongation of the conductive layer;

applying a resistive layer onto the conductive layer, the conductive layer and resistive layer being adapted to generate heat when subjected to an electrical power source;

applying at least one of a fabric material, an adhesive, and a flame retardant material to either side of the substrate; and

positioning the foregoing assembly between an outer seating material and an inner seating material.

31. The method of claim 30, wherein the step of applying at least one of a fabric material, an adhesive, and a flame retardant material to either side of the substrate includes applying an adhesive over the resistive layer and applying a flame retardant fabric over the adhesive, and wherein the outer seating material is an upholstery fabric and the inner seating material is a foam rubber.