Programmable human tissue stimulator

Claims

I claim:

1. A programmable human tissue stimulator system comprising:

an implanted stimulating signal generator for generating body tissue stimulating pulses responsive to control signals,

an implanted memory means for storing control signals for controlling said stimulating signal generator,

external control means for generating a plurality of sets of signals, each set including control signals, and signals which represent a memory address in said memory means,

external means for transmitting said generated sets of signals;

an implanted receiver for receiving said sets of transmitted signals,

implanted means for verifying that the received signals in each set are accurate and for producing an accurate signal when each signal in a set has substantially either a first waveform or a second waveform,

an implanted memory address means for storing the memory address which is represented by the memory address representing signal in the set;

implanted means responsive to said accurate signal for entering selected ones of the received control signals in each set in the memory means at the memory address stored in said memory address means, and

implanted means for controlling said implanted stimulating signal generator with control signals from said memory.

2. A programmable human tissue stimulator system as recited in claim 1 wherein said means for verifying that the received signals in each set are accurate includes:

means for determining that each set of signals includes identification signals at preselected locations within the set and that each identification signal at its preselected location has a predetermined one of said first and second waveforms.

3. A programmable human tissue stimulator system as recited in claim 1 wherein there is included an implanted transmitter means for external transmission of signals applied thereto,

selector means for applying to said implanted transmitter means control signals which are stored in said memory means,

external receiver means for receiving the control signals transmitted by said implanted transmitter means, and

means for determining that the control signals received by said external receiver means correspond to the control signals generated by said means for generating control signals.

4. A programmable human tissue stimulator system as recited in claim 1 wherein said sets of signals comprise digital words, each digital word including identification bits at preselected locations within said word,

said means for verifying includes means for examining said preselected locations to determine the presence or absence of said identification bits.

5. A programmable human tissue stimulator system as recited in claim 1 wherein there is included an implanted transmitter means for external transmission of signals applied thereto,

coupling means connecting said implanted stimulating signal generator to the tissue to be stimulated,

detecting means connected to said coupling means for detecting the stimulating signal applied by said stimulating generator to said tissue, as well as any electrical signal produced by said tissue,

selector means for applying signals detected by said detecting means to said implanted transmitter means,

external receiver means for receiving the detected signals transmitted by said implanted transmitter means, and

means for diplaying the signals received by said external receiver means.

6. A programmable human tissue stimulator system as recited in claim 1 wherein said means for verifying that the received signals are accurate and producing an accurate signal indicative thereof includes,

a second external means for transmitting said generated set of signals,

a second implanted receiver for receiving said second set of signals transmitted by said second means for transmitting, and

means for comparing the set of signals received by said implanted receiver with the set of signals received by said second implanted receiver and producing said accurate signal if they are identical.

7. A programmable human tissue stimulator system as recited in claim 6 wherein said second external means for transmitting is a modulated light source, and

said second implanted receiver is a light to electrical signal transducer.

8. A programmable human tissue stimulator system as recited in claim 1 wherein said external control means includes:

means for generating a first signal for turning off and a second signal for turning on said implanted stimulating signal generator, and

implanted switch means for applying operating potential to said implanted stimulating signal generator responsive to said first signal and for discontinuing the application of said operating potential responsive to said second signal.

9. A programmable human tissue stimulator system as recited in claim 1 wherein said external control means includes means for generating successive sets of signals each of which when applied to said implanted stimulating signal generator causes only a predetermined incremental change in said implanted stimulating signal output.

10. A programmable human tissue stimulator system comprising:

an implanted stimulating signal generator for generating body tissue stimulating pulses responsive to control signals,

an implanted memory means for storing control signals for controlling said stimulating signal generator,

external control means for generating a plurality of sets of signals, each set including control signals,

external means for transmitting said generated sets of signals,

an implanted receiver for receiving said sets of transmitted signals,

implanted means for verifying that the received signals in each set are accurate and for producing an accurate signal when each signal in a set has substantially either a first waveform or a second waveform,

implanted means responsive to said accurate signal for entering selected ones of the received control signals in each set in a location in said memory means which is defined by other signals in the set,

implanted means for controlling said implanted stimulating signals generator with control signals from said memory, each set of signals comprises a word comprised of binary pulses, each binary pulse rising from a leading edge to a first predetermined amplitude which extends first for a predetermined interval thereafter, then said binary pulse extends for a second predetermined interval at an amplitude level determined by its binary value, and thereafter extends for a third predetermined interval at a second predetermined value,

means for determining that each signal has an acceptable waveform includes,

first means responsive to the leading edge of a binary pulse for generating a reset pulse responsive to a binary value amplitude level change during said second predetermined interval, and

second means responsive to the leading edge of a binary pulse for generating a reset pulse responsive to a change in said first predetermined amplitude during said first predetermined interval,

register means into which a received binary word is transferred from said implanted receiver, and

means for applying said reset signals to said register means to clear said register means.

11. A programmable human tissue stimulator system comprising:

an implanted stimulating signal generator for generatng, responsive to control signals, body tissue stimulating pulse trains having parameters which are determined by said control signals,

an implanted memory means for storing, at different locations, different parameter determining control words for determining the parameters of the pulse train output of said stimulating pulse signal generator,

external control means for generating digital word signals, each word including a first plurality of binary bits representing a parameter for a pulse train, a second plurality of binary bits representing the storage location of said parameter in memory, and a third plurality of binary bits representing patient identifying data,

an external transmitter for transmitting said digital word signals,

an implanted receiver for receiving said transmitted signals,

an implanted temporary storage means for storing word signals received by said receiver,

means for verifying that the waveform of the received binary bits in a word have a predetermined acceptable waveform and clearing said temporary storage if the waveform is not acceptable,

implanted means for storing patient identifying data,

means for comparing the received patient identifying data with stored patient identifying data and producing an acceptance signal if they are the same,

means responsive to said acceptance signal for transferring said first plurality of binary bits, from said temporary storage into the location in memory means indicated by said second plurality of binary bits, and

means responsive to said acceptance signal for clearing said temporary storage.

12. A programmable human tissue stimulator system as recited in claim 11 wherein there is included:

an implanted transmitter means for external transmission of signals applied thereto,

implanted selector means for selecting for application to said implanted transmitter means signals occurring at predetermined locations within the implanted circuits of said programmable human tissue stimulator system specified by selection signals,

said digital word signals generated by said external control means including a fourth plurality of binary bits representative of a selection signal,

means for applying a fourth plurality of binary bits received by said implanted receiver to said implanted selector means whereby said implanted transmitter transmits the signals from the location specified,

an external receiver for receiving the transmitted signals, and

means for utilizing the signals received by said external receiver.

13. A programmable human tissue stimulator system as recited in claim 11 wherein said implanted signal generator includes switch means for applying pulse wavetrains from said stimulating signal generator to tissue at different locations, and

means responsive to stored first pluralities of binary bits in said memory for controlling operation of said switch means.

14. A programmable human tissue stimulator system as recited in claim 11 wherein there is included:

a second external transmitter means for transmitting said generated word signals,

a second implanted receiver for receiving the signals transmitted by said second external transmitter means, and

means for comparing the first and second pluralities of binary bits received by said second implanted receiver, with the first and second pluralities of binary bits in said temporary storage and producing a temporary storage clear signal when they are not alike.

15. A programmable human tissue stimulator system as recited in claim 14 wherein said second external means for transmitting is a modulated light source, and

said second implanted receiver is light to electrical signal transducer.

16. A programmable human tissue stimulator system as recited in claim 14 wherein said second external means for transmitting is a means for generating a modulated sound, and

said second implanted receiver is a sound to electrical signal transducer.

17. A programmable human tissue stimulator system as recited in claim 14 wherein said second external means for transmitting is a means for generating a modulated magnetic field, and

said second implanted receiver is a magnetic field to electrical signal transducer.

18. A programmable human tissue stimulator system as recited in claim 11 wherein said external control means includes means for generating successive control signals each of which when applied to said implanted stimulating signal generator causes only a predetermined incremental change in said implanted stimulating signal output.

19. A programmable human tissue stimulator system as recited in claim 11 wherein each of the pulses of said pulse trains generated by said implanted stimulating signal generator are biphasic pulses.

20. A programmable human tissue stimulator system as recited in claim 11 wherein each of the digital word signals generated by said external control means includes redundant binary bits at predetermined spaced locations in a word, and there is included:

means for verifying the presence of said redundant binary bits at said predetermined locations and preventing said means for comparing producing an acceptance signal when said redundant binary bits are not at said predetermined locations.

21. A programmable human tissue stimulator system as recited in claim 4 wherein said external control means includes:

means for generating a first signal for turning off and a second signal for turning on said implanted stimulating signal generator, and

implanted switch means for applying operating potential to said implanted stimulating signal generator responsive to said first signal and for discontinuing the application of said operating potential responsive to said second signal.

22. A programmable human tissue stimulator system as recited in claim 11 wherein there is included an implanted reference level signal source, and

said external means for generating digital word signals includes means to specify a word signal for instructing said implanted digitally responsive switch means to connect to said implanted reference level signal source, whereby the signal received by said external receiver means will be a calibration signal.

23. A system for obtaining electrical biophysical signals from electrodes placed at a plurality of different tissue locations within a body comprising:

external means for generating digital word signals specifying a tissue location from which it is desired to obtain electrical biophysical signals,

an external transmitter for transmitting said digital word signals,

an implanted receiver for receiving said digital word signals,

an implanted transmitter for transmitting an electrical biophysical signal,

implanted switch means responsive to said digital word signals for selectively connecting to said implanted transmitter an electrode placed at a tissue location from among a plurality of electrodes placed at different tissue locations within said body, said location being specified by said digital word signal, whereby said implanted transmitter will transmit electrical biophysical signals from said tissue location, and

external receiver means for receiving said transmitted electrical biophysical signals.

24. A programmable human tissue stimulator system comprising:

an implanted stimulating signal generator for generating body tissue stimulating pulses responsive to control signals,

an implanted memory means for storing control signals, for controlling said stimulating signal generator,

external control means for generating a plurality of sets of signals, each set including at least control signals, several of said sets further including memory location signals,

means for transmitting each of said generated sets of signals,

an implanted receiver for receiving each of said transmitted sets of signals,

means for verifying that the received signals in each set are accurate and producing an accurate signal indicative thereof only when each signal in the set has substantially either a first or a second waveform,

means responsive to said accurate signal for entering said received control signals in said memory means, at a location defined by the memory location signals in the set,

means responsive to certain ones of said control signals in said memory means for controlling said generator to establish the frequency of the body tissue stimulating pulses which it generates,

means responsive to others of said control signals in said memory means for controlling said generator to establish the periods of bursts of the body tissue stimulating pulses which it generates, and

means responsive to still others of said control signals in said memory means for controlling said generator to establish the amplitude of the body tissue stimulating pulses which it generates.

25. A programmable human tissue stimulator system as recited in claim 24 wherein said body tissue stimulating pulses are adapted to be applied to more than one body tissue, through plural applicator means,

said means responsive to others of said control signals in said memory for controlling said generator to establish the periods of bursts of the body tissue stimulating pulses includes means for controlling the timing of the application of said periods of bursts to said plural applicator means which are adapted to apply them to each of said more than one body tissue.

26. A programmable human tissue stimulator system comprising

an implanted stimulating signal generator for generating, responsive to control signals, body tissue stimulating pulse trains having parameters which are determined by said control signals,

an implanted memory means for storing, at different locations, different parameter determining control words for determining the parameters of the pulse train output of said stimulating pulse signal generator,

external control means for generating digital word signals, each word including a first plurality of binary bits representing a parameter for a pulse train, a second plurality of binary bits representing the storage location of said parameter in memory, and a third plurality of binary bits representing identifying data,

an external transmitter for transmitting said digital word signals,

an implanted receiver for receiving said transmitted signals,

an implanted temporary storage means for storing word signals received by said receiver,

implanted means for storing identifying data,

means for comparing the received identifying data with stored patient identifying data and producing an acceptance signal if they are the same,

means responsive to said acceptance signal for transferring said first plurality of binary bits, from said temporary storage into the location in memory means indicated by said second plurality of binary bits, and

means responsive to said acceptance signal for clearing said temporary storage.

27. A programmable human tissue stimulator system as recited in claim 26 wherein there is included:

an implanted transmitter means for external transmission of signals applied thereto,

implanted selector means for selecting for application to said implanted transmitter means signals occurring at predetermined locations within the implanted circuits of said programmable human tissue stimulator system specified by selection signals,

said digital word signals generated by said external control means including a fourth plurality of binary bits representative of a selection signal, instructing said selector means to apply the patient identifying word to said implanted transmitter means to be transmitted externally,

an external receiver for receiving the transmission of said implanted transmitter means, and

means for displaying the identifying word received by said external receiver for verification.

28. A programmable human tissue stimulator system comprising:

an implanted stimulating signal generator for generating, responsive to control signals, body tissue stimulating pulse trains having parameters which are determined by said control signals,

an implanted memory means for storing, at different locations, different parameter determining control words for determining the parameters of the pulse train output of said stimulating pulse signal generator,

external control means for generating digital word signals, including a plurality of binary bits representing identifying data,

an external transmitter for transmitting said digital word signals,

an implanted receiver for receiving said transmitted signals, as implanted transmitter,

implanted means for storing identifying data,

means for comparing the received identifying data with the stored identifying data, and

means for selectively connecting said internal transmitter to said implanted means for storing identifying data to selectively transmit said stored identifying data.

29. A programmable human tissue stimulator system comprising:

an implanted stimulating signal generator responsive to different groups of control signals for generating body tissue stimulating pulses having characteristics which are functions of said groups of the control signals;

an implanted memory means for storing in a plurality of locations groups of control signals, for controlling said stimulating signal generator as a function of at least some of said groups of control signals;

external control means for generating any one of a plurality of sets of signals, each set including a group of control signals, some sets further including memory-address-defining signals;

means for transmitting each generated set of signals;

an implanted receiver for receiving said transmitted set of signals;

means for verifying that the received set of signals is accurate and producing an accurate signal indicative thereof, only when each signal in the set has substantially a first or a second waveform;

means responsive to said accurate signal for entering the control signals in the received set in said memory means, at a location, defined by said memory-address-defining signals in said received set, without affecting the control signals located in other locations; and

an implanted battery for continuously applying power to at least said generator and said memory means, independent of external power source means.

30. A programmable human tissue stimulator system as described in claim 29 wherein said external control means includes manually carriable and operable external control means for generating at least one of said sets of signals for transmission to said implanted receiver, said at least one set includes a group of control signals for varying at least one characteristic of said stimulating pulses.

31. A programmable human tissue stimulator system as described in claim 30 wherein said one characteristic is pulse amplitude.

32. A programmable human tissue stimulator system as described in claim 30 wherein said one characteristic is pulse frequency.

33. A programmable human tissue stimulator system as described in claim 20 wherein said manually carriable and operable external control means includes means for generating a set of signals which includes control signals for turning said signal generator on or off.

34. A programmable human tissue stimulator system as described in claim 30 further including implanted transmitter means for transmitting to said manually carriable external control means signals indicative of the control signals received therefrom.

35. A programmable human tissue stimulator system as described in claim 24 wherein said manually carriable external control means is adapted to be worn on a patient's wrist or attachable to form part of a patient's wearable item of jewelry.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to living tissue stimulators and, more particularly, to a programmable living tissue stimulator.

2. Description of the Prior Art

Various devices are presently in existence which are implantable in a human patient to stimulate body tissues. Among the best known of these devices is the cardiac pacemaker, which provides stimulating pulses to a patient's heart, via one or more electrodes, connected to the pacemaker through electrode leads. Many of the existing implantable cardiac pacemakers include a power source in the form of a battery, which is rechargeable by means of recharging power, transmitted to the implanted pacemaker from an external power source.

In recent years extensive research has been directed to develop stimulators for other than the heart, in order to relieve patients of the crippling effects of various physiological disorders. For example stimulators have been proposed to stimulate the brain, the spine, muscles, glands and organs or any other stimulatable matter. The stimulating pulses from these stimulators are intended to help patients, suffering from various disorders, e.g. cerebral palsy, spasticity, rigidity, epilepsy and other disorders, which are due to either improper, or the absence of natural stimulating pulses. Also, it has been appreciated that pain, such as phantom limb pain, resulting from a severed limb may be alleviated by applying stimulating pulses to the nerves proximal the damaged area. A workshop was held at the National Institute of Health, Bethesda, Maryland on Apr. 27-28, 1972, and a report of the workship entitled "Functional Neuromuscular Stimulation" was published in 1972 by the National Academy of Sciences, Washington, D.C.

Different disorders require different stimulations. That is, the various parameters of the stimulating pulses, such as pulse amplitude, pulse frequency, pulse width, and other pulse parameters have to be different for different disorders and may differ from patient to patient. Furthermore, even for the same patient, the parameters may have to be varied depending on the patient's condition at any given time. Clearly, it would be prohibitively expensive to fabricate a customized stimulator for each patient. Furthermore, even if tailor-made for a specific patient, the stimulator would have to be capable of varying the pulses' parameters in order to vary the stimulation to suit the patient's changing conditions. Also, in a stimulator designed to stimulate tissue at different locations in the body, e.g., the right and left hemispheres of the brain, it is important to be able to control the relationships between the pulses to be applied to the different brain portions.

The only practical solution to the problem is to provide a basic implanted stimulator system, hereinafter referred to as a human tissue stimulator (HTS), which is programmable, in response to signals which are transmitted to the HTS from a source external to the body, in order to vary the parameters of the pulses which the HTS is to provide, to suit the needs of each particular patient depending on his type and state of disorder. Since the patient's safety is paramount, it is obvious, that the programmable HTS must be extremely reliable. Also, it is very important to provide the programmer, e.g. a doctor, with an accurate indication of the parameters which were introduced into the HTS in order to verify that the proper parameters were accepted. Also in many cases it is desirable to observe the biological response to a stimulation by measuring the electrical potential produced by the tissues being stimulated.

Since we live in an environment which is noisy, i.e., one in which spurious electrical and other type signals, generally referred to as noise are present, it is extremely important that the signals which are transmitted to the implanted HTS to program it, in order to vary the parameters of the pulses provided thereby, are not affected or altered by the noise, and that, if affected the affected signals received by the HTS, do not cause improper pulse parameters, which, if permitted to be introduced and stored in the HTS may endanger the patient's life, particularly when stimulation takes place at such extremely sensitive parts of the body as the brain or the spine. Quite often a doctor after examining a patient may wish to change one or more of the parameters, e.g., pulse amplitude and not disturb the other parameters. Also, it is believed desirable to enable the patient himself to vary one or more selected parameters, if and when such variation is necessary, when the patient is away from the doctor's office. This capability may be desirable in order to alleviate unexpected discomfort or pain, as a result of the stimulating pulses and/or increase the stimulation when it is felt to be needed.

None of the known human tissue stimulators, which have been proposed to date, possess the desired capabilities as hereinbefore discussed. In the known stimulators, proposed to date, all parameters must be changed even when less than all of the parameters require change. Also, in most systems only the doctor can change the parameters, and even the doctor is not provided with a direct indication of the parameters introduced by him into the stimulator. Rather, the indication of the introduced parameters is provided indirectly, by recording or otherwise observing the response of the patient to the stimulating pulses, which are produced by the stimulator as a result of the doctor-introduced parameters. Furthermore, in the prior art during programming of the stimulator, the patient has to be practically in contact with the external programming unit, from which the programming signals are transmitted to the implanted stimulator, in order to minimize the effect of the ever-present noise. The patient cannot move about during programming and/or be at an appreciable distance, e.g., several feet, from the programming unit, which under some circumstances would be most desirable. For example, correcting a gait dysfunction by stimulating a nerve to a leg muscle to produce a normal walking motion.

OBJECTS AND SUMMARY OF THE INVENTION

It is a primary object of the present invention to provide a new improved programmable tissue stimulator.

Another object is to provide a programmable human tissue stimulator which is extremely reliable in that special means are included therein to practically insure that only the parameters chosen by a programmer to be stored in the stimulator are in fact stored therein.

Yet another object of the present invention is to provide a programmable human tissue stimulator in which one or more of the parameters stored therein, so as to control the characteristics of the stimulating pulses provided by the stimulator, may be varied without having to vary and change all the stored parameters.

These and other objects of the invention are achieved by providing an HTS which includes a plurality of memories in which are stored different parameters including all parameters necessary to control the characteristics of the stimulating pulses provided by the HTS. The HTS includes receiving and decoding circuitry, designed to receive digital signals in the form of multi-bit parameter words of unique formats and decode them. Special decoding criteria are employed to insure that only parameter words, which were not affected by noise, are permitted to vary the contents of any of the parameters in the memories. In the HTS of the present invention any one of the parameters, stored in any of the memories, may be changed without having to change or affect the parameters stored in the other memories. The contents of any one of the memories, as well as any one of several analog signals including biopotential signals may be transmitted out of the implanted HTS for verification purposes or other use. The HTS is operable to respond to doctor-programmed parameters, which are transmitted to the HTS from a master external programmer or from a patient-operated miniature control unit (MCU) with which the patient can affect the operation of the HTS and selected parameters stored therein.

The novel features of the invention are set forth with particularity in the appended claims. The invention will best be understood from the following description when read in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an embodiment of the invention.

FIG. 2 is a pulse waveform diagram shown to assist in an understanding of this invention.

FIG. 2a is a block schematic diagram exemplifying an oscillator which may be used with this invention.

FIG. 2b is a block schematic diagram of a pulse burst on/off timing generator.

FIG. 3a illustrates the contents of parameter words used by this invention.

FIG. 3b illustrates the contents of parameter words with redundancy.

FIG. 3c illustrates the contents of a parameter word which define the mode of its entry into a memory.

FIG. 3d is a drawing illustrating binary bit waveforms in accordance with this invention.

FIG. 4 is a block schematic of part of a decoder which is used in this invention.

FIG. 5 completes the decoderblock schematic diagram and also illustrates the input to memory.

FIG. 6 is a block schematic diagram illustrating an alternative system for transmitting parameter words to the HTS.

FIG. 7 is a table of pulse train modes used to stimulate two different tissues.

FIG. 8 is a waveform diagram illustrating modes of pulse wave trains applied to tissues.

FIG. 9 illustrates schematically a single pulse generator connected for stimulating two tissues, shown to illustrate problems which may arise.

FIGS. 10 and 11 illustrate a mode control circuit arrangement for applying pulses alternately to at least two tissues.

FIG. 12 is a mode control circuit arrangement for applying pulses simultaneously to at least two tissues.

FIG. 13 is a schematic diagram illustrative of an amplitude control arrangement which may be used.

FIG. 14 is a waveform diagram illustrating bipolar pulses which may be used for tissue stimulation.

FIG. 15 is a block schematic diagram illustrating circuits which may be used for the selector, in accordance with this invention.

FIG. 6 is a block schematic diagram of a circuit for enabling the HTS transmitter to transmit the signals selected by the selector used with this invention.

FIG. 17 is a block schematic diagram of a controller, which may be used with this invention.

FIG. 18 is a schematic diagram illustrating a patient's controller.

FIG. 19 is a circuit diagram illustrating how the power of an implanted HTS may be controlled from outside of the body.

FIG. 20 is a schematic diagram of circuits which may be used to insure that the signals transmitted to the HTS are for the intended HTS.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Attention is now directed to FIG. 1 which is a simplified block diagram useful in explaining different significant aspects of the HTS of the present invention. However, as will become apparent from the following description, the invention is not intended to be limited thereto. In FIG. 1, numeral 10 designates a human tissue stimulator (HTS) which is assumed to be implanted below the skin 12 of a patient. The circuitry shown to the left of the skin 12 represents circuitry, external to the patient. The HTS includes some parts which are included in any conventional prior art HTS. However, the pulse generator, amplifier and mode circuit, 14, is not believed conventional and is hereinafter simply referred to as pulse generator 14, whose function is to provide stimulating pulses. These pulses by means of electrode leads 15a and 15b are assumed to be applied to electrode pair A, located at tissue A (not shown), e.g., a nerve or a muscle to be stimulated. The pulse generator 14 as well as other circuits in the HTS 10 are assumed to be powered from a power source, such as a battery 16, and if desired through an up-converter 17. The function of the latter, when used, is to raise the battery voltage in order to power those circuits requiring voltage higher or lower than that provided by the battery 16.

The particular HTS 10, shown in FIG. 1, the battery 16 is assumed to be of the rechargeable type, although other types of batteries may be used. The HTS includes means adapted to receive recharging energy from a source external to the body in order to recharge the battery 16. For explanatory purposes the recharging means inside the HTS is represented by a coil 19 which in inductively coupleable to an external coil 21 which forms part of an external controller 22. Charging energy from the external coil 21 is coupled into the implanted coil 19. The coupled energy from coil 19 is applied to a charging circuit 23 which is connected to the battery 16 to recharge the latter. Various arrangements are well known in the art for recharging an implanted battery and therefore the recharging circuitry will not be described in any detail.

In accordance with this invention the HTS 10 further includes an antenna 25, which for explanatory purposes is assumed to be a transmit and a receive (T/R) antenna for radio frequency (RF) signals. In the receive mode, signals e.g., RF signals from the external controller 22 are transmitted by an external transmitting antenna 26, are received by the implanted antenna 25 and are supplied to an RF receiver 28. The signals from receiver 28 are supplied to a decoder 30, whose function will later be discussed in detail. In the transmit mode implanted antenna 25 is used to transmit RF signals supplied thereto from an implanted RF transmitter 32 to the external antenna 26 which, in the receive mode, sends these signals to the external controller 22, for purposes to be discussed later.

Briefly, the information or data in the RF signals, received by the receiving antenna 25 from the external antenna 26, is in the form of multi-bit parameter words which include parameter values or simply parameters, which are to be stored in parameter memories, which form part of the implanted HTS. In order to insure that the received parameter words are not affected by noise and truly represent proper parameters the signals from the receiver 28 are decoded in the decoder 30. Only if the received parameter words are found to be proper and unaffected by noise are the parameter words, contained in them permitted to be transferred to and stored in the parameters memories, which together with their controls are represented by numeral 35.

As will be explained hereinafter in detail,