Electrical heater with thermistor

• US 6,495,809 B2
• Filed: 03/01/2002
• Issued: 12/17/2002
• Est. Priority Date: 10/06/2000
• Status: Expired due to Term

• Current Assignee: Illinois Tool Works Inc.
• Original Assignee: Illinois Tool Works Inc.
• Inventors: Bulgajewski, Edward, Sharp, Larry L.
• Primary Examiner(s): PAIK, SANG YEOP
• Application Number:
  US10/086,921
• Publication Number:
  US 20020079311A1
• Time in Patent Office: 291 Days
• Field of Search: 219/538, 219/539, 219/541, 219/543, 219/548, 219/552, 338/307, 338/308, 338/309, 338/323, 338/324, 338/325, 338/326, 338/328, 338/330
• US Class Current: 219/548
• CPC Class Codes: H05B 2203/003 using serpentine layout
• CPC Class Codes: H05B 2203/005 using multiple resistive elements or resistive zones isolated from each other
• CPC Class Codes: H05B 2203/006 using interdigitated electrodes
• 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 2203/029 Heaters specially adapted for seat warmers
• CPC Class Codes: H05B 3/26 heating conductor mounted on insulating base for transparent areas H05B3/84, H05B3/86
• CPC Class Codes: H05B 3/342 heaters used in textiles
• CPC Class Codes: H05B 3/345 knitted fabrics
• CPC Class Codes: H05B 3/347 woven fabrics

Abstract

An electrical heater having a plurality electrodes disposed adjacently on a substrate in spaced apart relation and interconnected by a thermistor material, for example a positive temperature coefficient material. The electrodes each have at least one end portion and preferably two opposite end portions coupled to corresponding electrical terminal located at a common termination zone on the substrate. A spacing between adjacent electrodes may vary and adjacent electrodes may include interdigitated portions to vary the heat produced on select portions of the substrate.

Claims

1. An electrical heater comprising:

a substrate;

a plurality of electrical terminals, including a first electrical terminal, a second electrical terminal, a third electrical terminal and a fourth electrical terminal;

first and second electrodes disposed on the substrate in spaced apart relation, each of the first and second electrodes having first and second power application ends, the first electrical terminal in electrical contact with the first power application end of the first electrode, the second electrical terminal in electrical contact with the second power application end of the first electrode, the third electrical terminal in electrical contact with the first power application end of the second electrode and the fourth electrical terminal in electrical contact with the second power application end of the second electrode;

a first adjacent portion of the first and second electrodes having corresponding interdigitated electrode portions protruding therefrom, and another adjacent portion of the first and second electrodes devoid of interdigitated electrode portions;

a thermistor material electrically interconnecting the first and second electrodes; and

a voltage source connected to the first, second, third and fourth electrical terminals such that a summation of electrical paths between adjacent portions of the first and second electrodes is substantially the same from the first power application ends of the electrodes to the second power application ends of the electrodes.

2. The heater of claim 1, the thermistor material comprising a positive temperature coefficient material.

3. The heater of claim 2, the first and second electrodes each having the first and second power application ends located at a common termination zone on the substrate.

4. The heater of claim 3, the substrate being a fabric coated with the positive temperature coefficient material and the first and second electrodes disposed thereon.

5. The heater of claim 1, a spacing between a first portion of the first and second electrodes is greater than a spacing between a second portion of the first and second electrodes.

6. An electrical heater comprising:

a substrate;

a plurality of electrical terminals, including a first electrical terminal, a second electrical terminal, a third electrical terminal and a fourth electrical terminal;

first and second electrodes disposed on the substrate in spaced apart relation,

the first and second electrodes each having first and second opposite end portions located at a common termination zone on the substrate, the first electrical terminal in electrical contact with the first opposite end portion of the first electrode, the second electrical terminal in electrical contact with the second opposite end portion of the first electrode, the third electrical terminal in electrical contact with the first opposite end portion of the second electrode and the fourth electrical terminal in electrical contact with the second opposite end portion of the second electrode,

the first and second electrodes having interdigitated electrode portions protruding therefrom; and

a thermistor material electrically interconnecting the first and second electrodes.

7. The heater of claim 6, including a voltage source and a switch connected to the opposite end portions of the first and second electrodes such that a summation of electrical paths at adjacent portions along the first and second electrodes from one of the corresponding end portions thereof to the other corresponding end portion thereof is substantially the same.

8. An electrical heater, comprising:

a substrate;

a plurality of electrical terminals;

a plurality of first, second and third electrodes disposed on the substrate in spaced apart relation,

the second electrode located between the first and third electrodes,

the first, second and third electrodes each having opposite end portions located at a common termination zone of the substrate, each opposite end portion of each electrode having a corresponding different one of the plurality of electrical terminals connected thereto,

a thermistor material electrically interconnecting the first, second and third electrodes, and

a voltage source including switch means for directing a more positive first voltage to at least one first end of at least one electrode and a less positive second voltage to at least one second end of at least one electrode.

9. The heater of claim 8, the thermistor material comprising a positive temperature coefficient material.

10. The heater of claim 8, the switch means including a multi-pole, multi-position switch electrically coupled to the opposite end portions of the first, second and third electrodes.

11. The heater of claim 8, a plurality of electrical terminals fastened to the substrate at the common termination zone, each of the opposite end portions of the first, second and third electrodes electrically coupled to a corresponding one of the plurality of electrical terminals.

12. The heater of claim 8, the voltage source connected to the opposite end portions of the first, second and third electrodes such that a summation of electrical paths along the first and third electrodes between the opposite end portions thereof is substantially the same when a more positive voltage is applied to at least one of the end portions of the first and third electrodes and a less positive voltage is applied to at least one of the opposite end portions of the first and third electrodes.

13. The heater of claim 8, the voltage source connected to the opposite end portions of the first, second and third electrodes such that a summation of electrical paths along the first and second electrodes between the opposite end portions thereof is substantially the same when a more positive voltage is applied to at least one of the end portions of the first and second electrodes and a less positive voltage is applied to at least one of the opposite end portions of the first and second electrodes.

14. The heater of claim 8, the voltage source connected to the opposite end portions of the first, second and third electrodes such that a summation of electrical paths along the second and third electrodes between the opposite end portions thereof is substantially the same when a more positive voltage is applied to at least one of the end portions of the second and third electrodes and a less positive voltage is applied to at least one of the opposite end portions of the second and third electrodes.

15. The heater of claim 8, adjacent portions of the first, second and third electrodes being arranged in a generally serpentine pattern on the substrate.

17. The heater of claim 8, adjacent portions of at least two of the first, second and third electrodes having interdigitated electrode portions protruding therefrom.

18. The heater of claim 17, spacing between adjacent portions of at least two of the first, second and third electrodes varies.

19. The heater of claim 8, the substrate being a fabric coated with a positive temperature coefficient material, and the first, second and third electrodes being screen printed thereon.

16. An electrical heater, comprising:

a substrate;

a plurality of first, second and third electrodes disposed on the substrate in spaced apart relation;

the second electrode located between the first and third electrodes, the second electrode being wider than the first and third electrodes;

the first, second and third electrodes each having opposite end portions located at a common termination zone of the substrate;

a thermistor material electrically interconnecting the first, second and third electrodes; and

a voltage source including switch means for directing a more positive first voltage to at least one first end of at least one electrode and a less positive second voltage to at least one second end of at least one electrode.

20. An electrical heater comprising:

a substrate;

a plurality of electrical terminals, including a first electrical terminal, a second electrical terminal, a third electrical terminal and a fourth electrical terminal;

first and second electrodes disposed on the substrate in spaced apart relation, each electrode having first and second power application ends, the first electrical terminal in electrical contact with the first power application end of the first electrode, the second electrical terminal in electrical contact with the second power application end of the first electrode, the third electrical terminal in electrical contact with the first power application end of the second electrode and the fourth electrical terminal in electrical contact with the second power application end of the second electrode;

a spacing between some adjacent portions of the first and second electrodes different than a spacing between other adjacent portions of the first and second electrodes;

a thermistor material electrically interconnecting the first and second electrodes; and

a voltage source connected to the power application ends such that a summation of electrical paths between adjacent portions of the first and second electrodes is substantially the same from the first power application ends of the electrodes to the second power application ends of the electrodes.

21. The heater of claim 20, the first and second electrodes each having corresponding opposite end portions located at a common termination zone of the substrate.

22. The heater of claim 21, some adjacent portions of the first and second electrodes having interdigitated portions protruding therefrom, and other adjacent portions of the first and second electrodes being devoid of interdigitated portions.