Use of telemetry coil to replace magnetically activated reed switch in implantable devices
US4541431A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 20, 1984 |
| Grant date | Sep 17, 1985 |
| Priority date | — |
| Expiry date | Sep 20, 2004 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S128/903
- WIPO fieldMedical technology
- WIPO sectorInstruments
Abstract
A combined telemetry system and magnetic field sensor for use in an implantable medical device. The telemetry system includes a conventional resonant circuit for transmitting and receiving data. The resonant circuit has a coil which is also used to sense the presence of a magnetic field exceeding a threshold value. The resonant frequency varies with the strength of the magnetic field which passes through the coil. Periodically, the resonant circuit is energized, and during a sensing window of predetermined duration which then immediately follows the voltage across the coil is examined for a predetermined number of zero crossings. That number of zero crossings will occur only in the presence of a magnetic field whose amplitude exceeds the threshold value. It is possible to achieve a sensitivity in such a system which is comparable to that of conventional miniature reed switches.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.