초록 ▼

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

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.

대표청구항 ▼

[What is claimed is:] [1.]eternal driver means for generating an ac power signal at a fixed frequency;an external coil for receiving the ac power signal and inductively coupling the ac power signal to the implantable device;an impedance matching circuit interposed between the external coil and exter

[What is claimed is:] [1.]eternal driver means for generating an ac power signal at a fixed frequency;an external coil for receiving the ac power signal and inductively coupling the ac power signal to the implantable device;an impedance matching circuit interposed between the external coil and external driver means for setting an output impedance of the power coupling system, the impedance matching circuit having means for adjusting the output impedance as a function of a control signal;directional coupler means coupled to the ac power signal for sensing reverse power;signal processing means for generating the control signal as a function of the sensed reverse power, and applying the control signal to the impedance matching circuit so as to adjust the output impedance to match the input impedance of the implantable device.