Capacitive occupancy detector apparatus
US4796013A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 15, 1986 |
| Grant date | Jan 3, 1989 |
| Priority date | — |
| Expiry date | Oct 15, 2006 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01H3/141
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A capacitive occupancy detector apparatus includes a personnel containment device having first and second electrodes which will define an electric field therebetween which will be intercepted by a person present in the containment device. A detecting device is provided for detecting the capacitance formed between the first and second electrodes and a processor is provided for storing the capacitance at predetermined periods. The difference between the last capacitance detected and a capacitance previously stored is detected to determine the presence of a person when the difference indicates an increase of the capacitance exceeding a first predetermined threshold. A second threshold is set based upon the capacitance which determines the presence of a person so that the subsequent determination of the absence of a person is based upon detecting a decrease of the capacitance with respect to the second threshold.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.