Flat electrical resistance heating element
US4908497A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 27, 1989 |
| Grant date | Mar 13, 1990 |
| Priority date | — |
| Expiry date | Feb 27, 2009 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH05B2203/026
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
The invention is for a flat electrical heating resistance element, so called foil elements. Elements according to the invention can be used for many purposes, however, it is specially intended for use as heating elements for water beds. The object of the invention is to minimize the electromagnetic fields caused by the elements. The influence of such magnetic fields on humans is on the whole unknown why there is a common desire that the strength of these magnetic fields shall be as low as possible in order to minimize effects, if any. Heating elements according to the invention have electrical resistance wire or band placed in loops on a plastic foil surface, whereby the loops have four with each other parallel conductors, electrically connected so that in any given moment the direction of the current in the two outer conductors are in the same direction and in the two inner conductors in the same direction opposite to the outer conductors.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.