Implantable cochlear stimulator having backtelemetry handshake signal

• US 5,569,307 A
• Filed: 10/12/1994
• Issued: 10/29/1996
• Est. Priority Date: 09/22/1989
• Status: Expired due to Term

• Current Assignee: Alfred E. Mann Foundation For Scientific Research
• Original Assignee: Alfred E. Mann Foundation For Scientific Research
• Inventors: Schulman, Joseph H., Gord, John C., Wolfe, James H., Strojnik, Primoz, Whitmoyer, David I.
• Primary Examiner(s): Kamm, William E.
• Assistant Examiner(s): LAYNO, CARL HERNANDZ
• Application Number:
  US08/322,066
• Time in Patent Office: 748 Days
• Field of Search: 607/55, 607/56, 607/57, 607/32, 607/60
• US Class Current: 607/56
• CPC Class Codes: A61N 1/36038 Cochlear stimulation
• CPC Class Codes: A61N 1/36185 Selection of the electrode configuration
• CPC Class Codes: A61N 1/37252 Details of algorithms or data aspects of communication system, e.g. handshaking, transmitting specific data or segmenting data
• CPC Class Codes: H04R 2460/03 Aspects of the reduction of energy consumption in hearing devices
• CPC Class Codes: H04R 25/505 using digital signal processing

Abstract

An external wearable processor (WP) of a cochlear stimulating system transmits a data signal to an implanted cochlear stimulator (ICS). The ICS is controlled through the data signal so that cochlear stimulation is provided by the ICS only after a determination is made that the WP is in proper signal contact therewith, and that the ICS is functioning properly. The ICS extracts a raw power signal from the data signal and generates different operating voltages from the extracted raw power signal. A detector generates a power bad signal whenever one of the operating voltages is less than a reference voltage. The ICS also detects and generates a carrier detect signal when the data signal is being received. Clock signals are generated within the ICS, and a phase locked loop (PLL) lock signal is generated when the clock signals are phase locked to the data signal. ICS circuitry further checks the parity of the incoming data signal and generates a parity alarm signal whenever a parity error is detected. A back telemetry carrier signal is transmitted from the ICS only when a prescribed combination of the carrier detect, PLL lock, power bad, and parity alarm signals exist. The back telemetry carrier signal, when received at the WP, is used as a handshake signal to signal the WP that the ICS is in proper signal communication with the WP, and that operation of the ICS can proceed.

Claims

1. An implantable cochlear stimulator comprising:

(a) receiver means for receiving a data signal from an external transmitter, the data signal comprising a series of data frames separated by a parity bit signal and an end of frame signal, each data frame comprising a plurality of data words, each data word defining an amplitude for a tissue stimulating signal for a different output channel of the tissue stimulator, and a command word for controlling a processor means in the tissue stimulator, the receiver means including

data conditioner means for generating a carrier detect signal and conditioned data signal whenever said data conditioner means receives said data signal,

clock decoder means for generating a clock signal and a phase locked loop (PLL) lock signal, the PLL lock signal being generated only when the generated clock signal is phase-locked to the received said conditioned data signal, and

parity error detection means for generating a parity alarm signal whenever a parity error occurs within the data frame;

(b) power supply means coupled to said receiver means for extracting a raw power signal from the data signal, said raw power signal being used to provide operating power for the human tissue stimulator, the power supply means including

voltage downcoverter means for generating a plurality of different operating voltages from the raw power signal, and

power bad detector means connected to the voltage downconverter means for generating a power bad signal whenever at least one of the operating voltages is less than a prescribed reference voltage;

(c) a plurality of output channels, each having an electrode connected thereto, the electrode being insertable into a human cochlea;

(d) processor means for serially processing the plurality of data words and command word in each data frame received by the receiver means and including

a command detector responsive to the command words for controlling the functions of the processor,

data word latching means for successively storing the data words, and

switch means for successively coupling voltages representative of output signals from the data word latching means to successive ones of the output channels; and

(e) back telemetry means for generating a back telemetry carrier signal, receivable by an external receiver, only when a prescribed combination of said carrier detect signal, PLL lock signal, power bad signal, and parity error signal exists, said back telemetry carrier signal serving as a handshake signal for the external receiver.

2. The implantable cochlear stimulator of claim 1 wherein the prescribed combination of the carrier detect signal, PLL lock signal, power bad signal, and parity error signal that causes the back telemetry carrier signal to be generated comprises the presence of the carrier detect signal and the PLL lock signal, and the absence of the power bad signal and the parity error signal, whereby the handshake signal to the external receiver only occurs when the data signal is being received by the receiver means, a clock signal has been generated that is phase-locked to the data signal, no parity errors are being detected in the data frames, and raw power is being successfully extracted from the data signal, with at least one correct operating voltages being present.

3. The implantable cochlear stimulator of claim 1 wherein each of said carrier detect signal, PLL lock signal, power bad signal, and parity error signal may assume an asserted or non-asserted state, with the asserted state being assumed when a prescribed condition is present, and the non-asserted state being assumed when the prescribed condition is not present, and wherein the prescribed combination of the carrier detect signal, PLL lock signal, power bad signal, and parity error signal that causes the back telemetry carrier signal to be generated comprises the asserted state of the carrier detect signal and the PLL lock signal, and the non-asserted state of the power bad signal and the parity error signal, with the handshake signal thereby being presented to the external receiver only when the data signal is being received by the receiver means, a clock signal is generated that is phase-locked to the data signal, no parity errors are detected in the data frames, and raw power is successfully extracted from the data signal, with at least one correct operating voltage being derived therefrom.

4. The implantable cochlear stimulator of claim 1 further including means for modulating the back telemetry carrier signal with status data indicative of selected monitored parameters within the implantable cochlear stimulator, whereby an external receiver may demodulate the back telemetry carrier signal to recover said status data.

5. A cochlear stimulator system comprising:

a wearable processor (WP); and

an implantable cochlear stimulator (ICS);

the WP including;

a headpiece having an external coil, and

means for generating a data signal and applying it to the external coil in the headpiece, the data signal comprising a series of data frames separated by a parity bit signal and an end of frame signal, each data frame comprising a plurality of data words, each data word defining an amplitude for a cochlear stimulating signal for a different output channel of the ICS, and a command word for controlling a processor means in the ICS;

the ICS including;

receiver means, including an implanted coil inductively coupled to the external coil of the headpiece, for receiving the data signal from the WP,

data conditioner means connected to said receiver means for generating a carrier detect signal and a conditioned data signal whenever said data signal is being received,

clock decoder means connected to said data conditioner means for generating a clock signal and a phase locked loop (PLL) lock signal, the PLL lock signal being generated only when the generated clock signal is phase-locked to the conditioned data signal,

parity error detection means for receiving said conditioned data signal and generating a parity alarm signal whenever a parity error occurs within the data frame;

power supply means coupled to the receiver means for extracting a raw power signal from the data signal, the raw power signal being used to provide operating power for the ICS,

voltage downcoverter means for generating a plurality of different operating voltages from the raw power signal,

power bad detector means for generating a power bad signal whenever at least one of the plurality of different operating voltages is less than a prescribed reference voltage;

a plurality of output channels, each having an electrode connected thereto, the electrode being insertable into a human cochlea;

processor means for serially processing the plurality of data words and command word in each data frame received by the receiver means, including a command detector responsive to the command words for controlling the functions of the processor, data word latching means for successively storing the data words, and switch means for successively coupling voltage signals representative of output signals from the data word latching means to successive ones of the plurality of output channels, and

back telemetry means for generating a back telemetry carrier signal receivable by the WP only when a prescribed combination of said carrier detect signal, PLL lock signal, power bad signal, and parity alarm signal exists, said back telemetry carrier signal thereby serving as a handshake signal for the WP;

the WP further including means for receiving the back telemetry carrier signal and controlling the ICS, via the control word sent in each data frame, so that the ICS does not generate any cochlear stimulating signals until such time as the ICS generates, and the WP receives, the back telemetry carrier signal.

6. The cochlear stimulation system of claim 5 wherein the WP further includes means for responding to the absence of the back telemetry carrier signal as an indication of a system defect in the ICS, and for initiating a restart mode of the ICS and continuing in such restart mode, until the back telemetry carrier signal is again detected.

7. The cochlear stimulation system of claim 6 further including means for modulating the back telemetry carrier signal with status data indicative of selected monitored parameters within the ICS, and wherein the WP includes means for demodulating the back telemetry carrier signal to recover the status data.

8. The cochlear stimulation system of claim 7 wherein the back telemetry means further includes telemetry multiplexer means for selecting one of a multiplicity of parameters within the ICS to modulate the back telemetry carrier signal as a function of a telemetry command signal received from the WP as part of the data signal.

9. The cochlear stimulation system of claim 7 wherein the back telemetry means further includes an analog-to-digital converter means for converting analog parameters selected by the telemetry multiplexer means to a digital signal prior to modulating of the back telemetry carrier signal, whereby the back telemetry carrier signal is modulated with the digital signal.

10. The cochlear stimulation system of claim 9 wherein the ICS further includes an indifferent electrode and means for switchably connecting the indifferent electrode in circuit relationship with at least one of the plurality of output channels in order to selectively provide monopolar stimulation.

11. The cochlear stimulation system of claim 10 wherein the telemetry multiplexer means selects one of the multiplicity of parameters for modulating the back telemetry carrier signal from the group comprising:

a tank voltage representative of the raw power signal extracted by the power supply means, the raw power signal, one of the plurality of different operating voltages derived from the raw power signal by the voltage downconverter means, the prescribed reference voltage used by the power bad detection means, output voltages appearing at an output of each output channel, a current signal representative of an output current generated by each output channel, an indifferent electrode voltage, and an indifferent electrode current.

12. A method of safely operating an implantable cochlear stimulator (ICS) having a plurality of output channels so that it generates a cochlear stimulating signal in a selected output channel only after it is properly in signal communication with and controlled by an external wearable processor (WP), comprising the steps of:

(a) generating a data signal in the WP and applying it to an external coil in a headpiece of the WP, the data signal comprising a series of data frames separated by a parity bit signal and an end of frame signal, each data frame comprising a plurality of data words, each data word defining an amplitude for a cochlear stimulating signal for a different output channel of the ICS, and a command word for controlling the ICS;

(b) receiving the data signal in an implanted coil of the ICS inductively coupled to the external coil of the headpiece;

(c) generating a carrier detect signal within the ICS whenever said data signal is being received;

(d) locking in phase said data signal with a generated clock signal;

(e) generating a clock signal and a phase locked loop (PLL) lock signal within the ICS, with the PLL lock signal being generated only when said locking in phase occurs;

(f) determining if a parity error exists within the data frame;

(g) generating a parity alarm signal based upon the result of said parity error determination;

(h) extracting a raw power signal from the data signal, and using the raw power signal to provide operating power for the ICS;

(i) generating a plurality of different operating voltages from the raw power signal;

(j) comparing at least one of the plurality of different operating voltages to a prescribed reference voltage;

(k) generating a power bad signal whenever the at least one of the plurality of different operating voltages is less than the prescribed reference voltage;

(l) serially processing the plurality of data words and command word in each data frame received by the receiver means in order to control the ICS, including successively storing the data words, and successively coupling voltage signals representative of output signals from the data words to successive ones of the plurality of output channels, and

(m) generating a back telemetry carrier signal receivable by the WP only when a prescribed combination of the carrier detect signal, PLL lock signal, power bad signal, and parity alarm signal exists, the back telemetry carrier signal thereby serving as a handshake signal for the WP;

(n) receiving the back telemetry carrier signal at the ICS and controlling the ICS, via the control word sent in each data frame, so that the ICS does not generate any cochlear stimulating signals until such time as the ICS generates, and the WP receives, the back telemetry carrier signal.

13. The method of claim 12 further including responding to the absence of the back telemetry carrier signal at the WP as an indication of a system defect in the ICS, and in response to such system defect indication initiating a restart mode of the ICS and continuing in such restart mode until the back telemetry carrier signal is detected.