Flexible self-regulating heating pad combination and associated method
US5451747A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 3, 1992 |
| Grant date | Sep 19, 1995 |
| Priority date | — |
| Expiry date | Mar 3, 2012 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH05B2203/035
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A flexible, electric heating pad having a self-limiting heating element is provided. The heating element includes a pair of relatively spaced conductors surrounded by a positive temperature coefficient (PTC) material. A layer of electrically insulating material surrounds the PTC material. The PTC material includes a polyolefin resin having a relatively low flexural modulus. The heating element is disposed in a generally serpentine configuration within passages formed in the covering material of the heating pad. The passages are formed by joining together layers of covering material using ultrasonic welding or other suitable ways. The temperature of the heating element is controlled using controller circuit which utilizes a solid state timed interval control circuit. A safety circuit is provided for non-resettably disconnecting electrical power from the heating element if short or open circuit conditions occur therein. A temperature indicator and a variable automatic shutoff circuit are also provided with the controller circuit. A method of making the heating pad is also provided.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.