Cochlear implant employing frequency-division multiplexing and frequency modulation

• US 5,069,210 A
• Filed: 04/17/1989
• Issued: 12/03/1991
• Est. Priority Date: 04/17/1989
• Status: Expired due to Fees

• Current Assignee: Smith & Nephew Richards Incorporated (Smith & Nephew PLC)
• Original Assignee: Smith & Nephew Richards Incorporated (Smith & Nephew PLC)
• Inventors: Jeutter, Dean C., Han, James C., Josse, Fabien J.
• Primary Examiner(s): Cohen, Lee S.
• Assistant Examiner(s): PONTIUS, KEVIN LANE
• Application Number:
  US07/339,479
• Time in Patent Office: 960 Days
• Field of Search: 128/420.5, 128/420.6, 128/419 R, 455/41, 600/25
• US Class Current: 607/57
• CPC Class Codes: A61N 1/36038 Cochlear stimulation

Abstract

A cochlear prosthesis composed of a transmitter part which is to be carried exterior to the user'"'"'s body and a receiver part which is to be implanted in the user, the transmitter and receiver parts being coupled by a radio link provided by implanted receiver coils and external transmitter coils free of any percutaneous connections. In the transmitter part, sound signals are obtained in plurality of channels, and these channels are frequency multiplexed into a composite signal with the aid of a plurality of surface acoustic wave filters, each having a respective passband. In the implanted receiver, the received composite signal is frequency demultiplexed by means of a similar plurality of surface acoustic wave filters each having a respective passband. A further signal is transmitted from the transmitter part to the receiver part via the radio link in order to supply operating power for the circuits in the receiver part, where the further signal is rectified to produce d.c. operating voltages.

Claims

1. A cochlear prosthesis comprising:

a transmitter part arranged to be carried by a user and comprising;

a sound-to-electrical signal transducer for deriving an electrical analog signal representative of incident acoustic signals in the audible frequency range;

sound processing means connected to said transducer for dividing the electrical analog signal into a plurality of component signals;

frequency modulating means connected to said sound processing means for deriving a plurality of frequency modulated signals each having a respectively different center frequency and each frequency modulated with a respective component signal;

bandpass filter means composed of a plurality of first filter elements, each element being connected to receive a respective frequency modulated signal from said frequency modulating means and having a selected pass band centered on a respective center frequency of said frequency modulating means;

frequency multiplexing means connected to said filter means for combining the signals passed by all of said filter elements; and

transmitting antenna means connected to said frequency multiplexing means for emitting a radiation signal corresponding to the signals combined by said frequency multiplexing means; and

a receiver part arranged to be surgically implanted in the user'"'"'s body and comprising;

receiving antenna means arranged to be positioned in proximity to said transmitting antenna means for converting the radiation signal emitted by said transmitting antenna means into a received signal corresponding to the signals combined by said frequency multiplexing means;

frequency demultiplexing means including a plurality of second filter elements, said frequency demultiplexing means being connected to said receiving antenna means for causing each said second filter element to pass a respective portion of the received signal lying in a respective frequency band;

demodulator and amplifier means connected to said frequency demultiplexing means for individually demodulating and amplifying the signal portion passed by each said second filter element; and

a plurality of output electrodes each arranged to be implanted at a selected location in a cochlea of the user and each connected to said amplifier means for receiving a respective individually amplified received signal portion,

wherein said first filter elements are surface acoustic wave filters.

2. A prosthesis as defined in claim 1 wherein said second filter elements are surface acoustic wave filters.

3. A prosthesis as defined in claim 2 wherein said frequency multiplexing means comprise a plurality of inductors connected to form a constant-k ladder circuit which is connected between said surface acoustic wave filters and said transmitting antenna means.

4. A prosthesis as defined in claim 2 wherein said transmitter part and said receiver part are composed entirely of analog signal circuits.

5. A cochlear prosthesis comprising:

a transmitter part arranged to be carried by a user and comprising;

a sound-to-electrical signal transducer for deriving an electrical analog signal representative of incident acoustic signal in the audible frequency range;

sound processing means connected to said transducer for dividing the electrical analog signal into a plurality of component signals;

frequency modulating means connected to said sound processing means for deriving a plurality of frequency modulated signals each having a respectively different center frequency and each frequency modulated with a respective component signal;

bandpass filter means composed of a plurality of first filter elements, each element being connected to receive a respective frequency modulated signal from said frequency modulating means and having a selected pass band centered on a respective center frequency of said frequency modulating means;

frequency multiplexing means connected to said filter means for combining the signals passed by all of said filter elements; and

transmitting antenna means connected to said frequency multiplexing means for emitting a radiation signal corresponding to the signals combined by said frequency multiplexing means; and

a receiver part arranged to be surgically implanted in the user'"'"'s body and comprising;

receiving antenna means arranged to be positioned in proximity to said transmitting antenna means for converting the radiation signal emitted by said transmitting antenna means into a received signal corresponding to the signals combined by said frequency multiplexing means;

frequency demultiplexing means including a plurality of second filter elements, said frequency demultiplexing means being connected to said receiving antenna means for causing each said second filter element to pass a respective portion of the received signal lying in a respective frequency band;

demodulator and amplifier means connected to said frequency demultiplexing means for individually demodulating and amplifying the signal portion passed by each said second filter element; and

a plurality of output electrodes each arranged to be implanted at a selected location in a cochlea of the user and each connected to said amplifier means for receiving a respective individually amplified received signal portion,

wherein said frequency modulating means comprise a plurality of phase locked loops each connected to derive a respective frequency modulated signal from a respective component signal.

6. A cochlear prosthesis comprising:

a transmitter part arranged to be carried by a user and comprising;

a sound-to-electrical signal transducer for deriving an electrical analog signal representative of incident acoustic signal in the audible frequency range;

sound processing means connected to said transducer for dividing the electrical analog signal into a plurality of component signals;

frequency modulating means connected to said sound processing means for deriving a plurality of frequency modulated signals each having a respectively different center frequency and each frequency modulated with a respective component signal;

bandpass filter means composed of a plurality of first filter elements, each element being connected to receive a respective frequency modulated signal form said frequency modulating means and having a selected pass band centered on a respective center frequency of said frequency modulating means;

frequency multiplexing means connected to said filter means for combining the signals passed by all of said filter elements; and

transmitting antenna means connected to said frequency multiplexing means for emitting a radiation signal corresponding to the signals combined by said frequency multiplexing means; and

a receiver part arranged to be surgically implanted in the user'"'"'s body and comprising;

receiving antenna means arranged to be positioned in proximity to said transmitting antenna means for converting the radiation signal emitted by said transmitting antenna means into a received signal corresponding to the signals combined by said frequency multiplexing means;

frequency demultiplexing means including a plurality of second filter elements, said frequency demultiplexing means being connected to said receiving antenna means for causing each said second filter element to pass a respective portion of the received signal lying in a respective frequency band;

demodulator and amplifier means connected to said frequency demultiplexing means for individually demodulating and amplifying the signal portion passed by each said second filter element; and

a plurality of output electrodes each arranged to be implanted at a selected location in a cochlear of the user and each connected to said amplifier means for receiving a respective individually amplified received signal portion,

wherein said frequency demultiplexing means comprise a plurality of inductors connected to form a constant-k ladder circuit which is connected between said receiving antenna means and said plurality of second filter elements.