Directional detector of changes in a local electrostatic field
US4316180A · kind A · utility
Inventor
Key dates
| Filing date | Apr 9, 1979 |
| Grant date | Feb 16, 1982 |
| Priority date | — |
| Expiry date | Apr 9, 1999 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG08B13/26
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
A directional detector of changes in a local electrostatic field comprising two parallel flat coils of copper wire, separated by an electrically grounded plane rectangular conductor that is coated on both sides with an insulator, and associated signal conditioning electronics has been constructed. The combination of coils and plane rectangular conductors forms two independent wideband antennas which, when placed in an unobstructed electromagnetic radiation field, have induced in them electric currents of equal peak-to-peak values. When the combination was brought near an ungrounded body, such as a person standing on an insulator to earth, a coupling of high frequency potentials of the ungrounded body and the nearest coil occurred, while the coil farthest away from the body, due to the presence of the electrically grounded plane rectangular conductor, was unaffected. The coupling of high frequency potentials caused an increase in the amplitude of the electric current in the affected coil which was used in conjunction with the electric current in the unaffected coil, and the signal conditioning electronics to activate an alarm unit.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.