Proximity switch immune to interference fields
US4841163A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 16, 1988 |
| Grant date | Jun 20, 1989 |
| Priority date | — |
| Expiry date | Feb 16, 2008 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03K17/16
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A proximity switch immune to interference fields includes an oscillator circuit (1) that can be influenced by a permanent magnet, this circuit being damped in the basic condition by a core of a coil (13), which core consists of an amorphous metal, and being undampable by the approach of the permanent magnet. In order to prevent triggering of the proximity switch by a magnetic alternating field, a signal evaluating circuit (2), yielding a switching signal corresponding to the undamped condition of the oscillator circuit (1), and a signal evaluating circuit (8) are connected to the oscillator circuit output (17). The signal evaluating circuit (8) detects an output signal produced by a magnetic alternating field separately as interference and blocks, by way of a blockable holding circuit (5), the switching signal path so long as a magnetic alternating field is present.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.