Flexible electric heating pad using PTC ceramic thermistor chip heating elements
US4937435A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 15, 1989 |
| Grant date | Jun 26, 1990 |
| Priority date | — |
| Expiry date | Mar 15, 2009 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH05B2203/02
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A flexible electric heating pad has a plurality of positive temperature coefficient (PTC) ceramic thermistor chip heating elements arranged in a two dimensional array between first and second flexible planar sheets of electrically conductive material, preferably woven of copper wire or other electrically conductive fibers. The PTC thermistor chips are disposed in spaced openings in a flexible dielectric separator disposed between the sheets and each chip has opposed planar surfaces soldered, welded or brazed to the sheets to establish electrical and thermal contact therewith. An outer flexible dielectric material covers the external surfaces of the sheets to prevent grounding or shock. A metallic enclosure, for example of stainless steel, can be formed over the outer dielectric material to add corrosion or abrasion resistance to the flexible heating pad.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.