Power transfer circuit for implanted devices
US6212431A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 18, 1999 |
| Grant date | Apr 3, 2001 |
| Priority date | — |
| Expiry date | Aug 18, 2019 |
Classification
- Technology area (CPC A)Human Necessities
- CPC primaryA61N1/36038
- WIPO fieldMedical technology
- WIPO sectorInstruments
Abstract
An external power transfer circuit (12) couples ac power having a fixed frequency into an implantable electrical circuit (14), e.g., an implantable tissue stimulator, while automatically maintaining optimum power transfer conditions. Optimum power transfer conditions exist when there is an impedance match between the external and implanted circuits. The external transfer circuit includes a directional coupler (42) and an impedance matching circuit (44). The directional coupler senses the forward power being transferred to the implant device, as well as the reverse power being reflected form the implant device (as a result of an impedance mismatch). The impedance matching circuit includes at least one variable element controlled by a control signal. The sensed reverse power is used as a feedback signal to automatically adjust the variable element in the impedance matching circuit, and hence the output impedance of the external power transfer circuit, so that it matches the input impedance of the implant device, despite variations that occur in the input impedance of the implant device due to variations in implant distance and implant load.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.