CA1129012A - Transcutaneous pain reliever - Google Patents
Transcutaneous pain relieverInfo
- Publication number
- CA1129012A CA1129012A CA329,209A CA329209A CA1129012A CA 1129012 A CA1129012 A CA 1129012A CA 329209 A CA329209 A CA 329209A CA 1129012 A CA1129012 A CA 1129012A
- Authority
- CA
- Canada
- Prior art keywords
- assembly
- energy
- pain reliever
- battery
- external electrode
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
- A61N1/00—Electrotherapy; Circuits therefor
- A61N1/18—Applying electric currents by contact electrodes
- A61N1/32—Applying electric currents by contact electrodes alternating or intermittent currents
- A61N1/36—Applying electric currents by contact electrodes alternating or intermittent currents for stimulation
- A61N1/36014—External stimulators, e.g. with patch electrodes
- A61N1/36021—External stimulators, e.g. with patch electrodes for treatment of pain
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- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Radiology & Medical Imaging (AREA)
- Animal Behavior & Ethology (AREA)
- Heart & Thoracic Surgery (AREA)
- Engineering & Computer Science (AREA)
- Biomedical Technology (AREA)
- Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
- Pain & Pain Management (AREA)
- Biophysics (AREA)
- General Health & Medical Sciences (AREA)
- Public Health (AREA)
- Veterinary Medicine (AREA)
- Charge And Discharge Circuits For Batteries Or The Like (AREA)
- Electrotherapy Devices (AREA)
- Magnetic Treatment Devices (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A transcutaneous pain reliever utilizes a plurality of battery powered inductive energy generators, which are sequentially and individually activated, a clocking system which automatically inhibits pulsing of each energy generator until a previous one of the energy generators has delivered its energy, and an anti-adapt system to prevent a patient from becoming acclimated to the sensations. An energy absorption sensor indicates the amount of energy not absorbed by the electrodes and a bridged, transformerless battery charger permits the use of inexpensive low power diodes and a battery saver permits excess energy to charge batteries.
A transcutaneous pain reliever utilizes a plurality of battery powered inductive energy generators, which are sequentially and individually activated, a clocking system which automatically inhibits pulsing of each energy generator until a previous one of the energy generators has delivered its energy, and an anti-adapt system to prevent a patient from becoming acclimated to the sensations. An energy absorption sensor indicates the amount of energy not absorbed by the electrodes and a bridged, transformerless battery charger permits the use of inexpensive low power diodes and a battery saver permits excess energy to charge batteries.
Description
l~Z9~lZ
TRANSCUTANEOUS PAIr~ RELIEVER
The present invention consists of a transcutaneous pain reliever which relieves pain by the electrical stimulation of part of a patient~s body.
While the mechanics of suppressing pain by electrical impulses is not yet completely known, two theories appear to have been developed. In one theory, the electrical impulses arrive at the central nervous system faster than the pain impulses in order to modulate the pain impulses. This theory indicates that electrical impulses travel through the larger nerve fibers at greater speeds whereas pain impulses travel through the smaller nerve fibers at slower rates.
A more recent theory which has been developed is the so-called "gate control" theory. According to that theory, pain relief is achieved because of the inhibition of certain nerve fibers by electrica~ly activating the larger nerve fibersO There is a "gate" in the spinal cord which blocks pain signals from reaching the brain. This gate is closed by electrical stimulation of the larger nerve fibers so as to block pain signals to the brain coming through the smaller nerve fibers.
Regardless of the accuracy of either theory, various ins~ruments using electric impulses to inhibit or suppress pain have been commercially available for many years. These existing instruments operate by exciting only a few electrodes attached to certain affected areas of the patient's body and are believed to be inadequate because Or the limited areas stimulated. If larger numbers of electrodes can be used, then larger areas can be stimulated to produce more effective pain relief. However, increased stimulation area cannot be achieved by simply increasing electrode size since most of the energy flows between the closest points of approach of the electrodes. In addition, increasin~
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excitation between electrodes will increase the current density through the skin. Furthermore, electrodes may inadvertently touch each other or be fired simultaneously or be superimposed on each other. These conditions may result in a sensation which may be more painful than the pain to be alleviated.
Hence, current instruments do not lend themselves to simple modification to accomplish the main objects of this invention, i.e. increasing the stimulation area without danger of injury to the patient and provide a form of stimulation which permits rather than forces the tissue to accept energy. Some of them deliver pulses of adjustable constant current at variable repetition rates. Others have adjustable compliance and some are capable of supplying the alectrodes either simultaneously or alternately. Still others supply unipolar excitation while some supply bipolar ones. Not all of the current instruments are constant current types. Some are high impedance pulse generators, other modulate the peaks of pulses while others do not. There appears to be as many waveforms as there are manufacturers with no consensus as to what is the best.
It is an object of the present invention to provide an improved transcutaneous pain reliever which mitigates the above problems and uses multiple electrode assemblies which will permit an increase in the area of stimulation without increasing current density so that there is no danger or unpleasant sensation to the patient.
The present invention provides a transcutaneous pain reliever, comprising a plurality of external electrode assemblies for supplying electrical excitations to a patient, means for sequentially and individually pulsing current through the external electrode assemblie~, means for interrupting the pulsing of the current through the external electrode assemblies and means responsive to the completion of a pulse from any one of the electrode assemblies to discontinue the interruption of
TRANSCUTANEOUS PAIr~ RELIEVER
The present invention consists of a transcutaneous pain reliever which relieves pain by the electrical stimulation of part of a patient~s body.
While the mechanics of suppressing pain by electrical impulses is not yet completely known, two theories appear to have been developed. In one theory, the electrical impulses arrive at the central nervous system faster than the pain impulses in order to modulate the pain impulses. This theory indicates that electrical impulses travel through the larger nerve fibers at greater speeds whereas pain impulses travel through the smaller nerve fibers at slower rates.
A more recent theory which has been developed is the so-called "gate control" theory. According to that theory, pain relief is achieved because of the inhibition of certain nerve fibers by electrica~ly activating the larger nerve fibersO There is a "gate" in the spinal cord which blocks pain signals from reaching the brain. This gate is closed by electrical stimulation of the larger nerve fibers so as to block pain signals to the brain coming through the smaller nerve fibers.
Regardless of the accuracy of either theory, various ins~ruments using electric impulses to inhibit or suppress pain have been commercially available for many years. These existing instruments operate by exciting only a few electrodes attached to certain affected areas of the patient's body and are believed to be inadequate because Or the limited areas stimulated. If larger numbers of electrodes can be used, then larger areas can be stimulated to produce more effective pain relief. However, increased stimulation area cannot be achieved by simply increasing electrode size since most of the energy flows between the closest points of approach of the electrodes. In addition, increasin~
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~129~1~
excitation between electrodes will increase the current density through the skin. Furthermore, electrodes may inadvertently touch each other or be fired simultaneously or be superimposed on each other. These conditions may result in a sensation which may be more painful than the pain to be alleviated.
Hence, current instruments do not lend themselves to simple modification to accomplish the main objects of this invention, i.e. increasing the stimulation area without danger of injury to the patient and provide a form of stimulation which permits rather than forces the tissue to accept energy. Some of them deliver pulses of adjustable constant current at variable repetition rates. Others have adjustable compliance and some are capable of supplying the alectrodes either simultaneously or alternately. Still others supply unipolar excitation while some supply bipolar ones. Not all of the current instruments are constant current types. Some are high impedance pulse generators, other modulate the peaks of pulses while others do not. There appears to be as many waveforms as there are manufacturers with no consensus as to what is the best.
It is an object of the present invention to provide an improved transcutaneous pain reliever which mitigates the above problems and uses multiple electrode assemblies which will permit an increase in the area of stimulation without increasing current density so that there is no danger or unpleasant sensation to the patient.
The present invention provides a transcutaneous pain reliever, comprising a plurality of external electrode assemblies for supplying electrical excitations to a patient, means for sequentially and individually pulsing current through the external electrode assemblie~, means for interrupting the pulsing of the current through the external electrode assemblies and means responsive to the completion of a pulse from any one of the electrode assemblies to discontinue the interruption of
- 2 -.
the pulsing of the current to a succeeding one of the electrode assemblies.
A preferred embodiment of the invention has been chosen for purposes of illustration and description and is shown in the accompanying drawings forming a part of the specification, wherein:
Figure 1 is a schematic view showing the circuitry of the battery charger, the clocXing system and the anti-adapt system used in accordance with the present invention.
Figure 2 is a schematic view showing an energy generator of the present invention with the lower part showing the parts in block diagram form, the central part showing the recommended values for the parts and the upper part showing the parts used.
Figure 3 is a schematic diagram showing the circuitry between the control connectors and the energy generators.
Figure 4, 5 and 6, which appear on the same sheet as Figure 1, show the waveforms generated at points A, B and C, of Figure 2.
Figure 7 is a diagramatic view of a simplified version of the energy generator as shown in Figure 2.
Figure 8 is a view similar to Figure 7 showing the use f a B
0~L2 battery saver energy spreader circuitu The battery charger of the present invention is shown schematically in ~ig. 1. The power for the instrument is obtained from a plurality or chain Or batteries Bl to ~40 A switch S3 controls the battery chain connections between CHARGE, OFF and ON.
The charger unit is a brldged, transformerless bridge rectifier unit which permits the use o~ low voltage inexpensive diodes (such as 25 V PIV,) on a 230 volt line. The battery charger comprises diodes D3, D4, D5 and D6 which are arranged as a bridge. A zener diode D8 is used across the output of the bridge. 2ener diode D8 permits the batteries Bl to B4 to be disconnected ~rom the bridge without subjecting the bridge diodes to large inverse voltages. The voltage passing zener D8 is no larger than the breakdown voltage of zener D8 so that the zener diode D8 protects the low voltage bridge diodes D3 to D6 when the battery is disconnected from the charger and the charging circuit ls still receiving power from the main power line.
Since the voltage of zener D8 is greater than the battery voltage, the zener D8 has no effect when the batteries Bl-B4 are connected to the charger by switch S3. However, if the batteries Bl-B4 are disconnected from the charger, the zener D8 absorbs the charging current while insuring that the maximum voltage across the bridge diodes D3-D6 is only slightly greater ; than it would have been with the batteriesin place. Thus, even though the charging voltage supply is very high, the bridge diodes D3-D6 require a rating only slightly greater than that of the zener diode voltage of D8 which in turn is only slightly greater than the battery voltage.
The voltage Or the zener diode D8 depends upon the i 3 battery requirements and, in the example illustrated, is preferably B
between 10 and 15 voltsO The batteries Bl-B4 are 150 milliampere-hour batteries which may be recharged at 15 milliamperes~
Preferably, they are nickel cadmium batteries of about 1.41 volts approximately, so that the battery chain total is 5.64 voltsO The LED D9 requires about 1 o6 volts and the reverse voltage protection diode D7 requires about 0~7 volts. Hence, breakdown voltage of .
zener diode D8 is such that no current passes through it when the battery assembly Bl B4 is c~nnected to the bridge D3-D6 by switch S3 .
being in the CHARGE position~ Under such circumstances, the 10 voltage from D7 to the cathode of zener D8 is approximately 8 .
volts so that if D8 is of greater voltagej e.gO about 10 volts, .
no current passesO
When the switch S3 is not in the CHARGE position but .
in the OFF or the ON positions, the output of the bridge D3-D6 is absorbed by zener diode D8. The current is limited by the resistors R15 and R16 to about 15 milliamperes under either 230 volt or the 115 volt depending upon the position of switch S4, some contacts o~ which are not used as a switch but rather as a set of points on which to mount the resistor R16. The inclusion ~20 of zener D8 across the bridge D3-D6 with the accompanying volta~e dropping resistors prevents the diodes in bridge D3-D6 from being subjected to any voltage greater than the breakdown voltage of the zener diode D8 in all positions o~ battery switch S3.
The energy generator chassis circuitry is incorporated ~ in a circuit separate from the control chassis containing the : batteries so that the physical interconnection of the two circuits makes it impossible to recharge the batterles while they are connected to the energy chassis. Hence, there can be no physical connection between the main po~er line and the person undergoing treat.~.ent ~Jhile the batteries are being charged since the batteries I
, ~12~0~;~
must be separated from the control chassis before they are - charged.
The improved clocking system Or the present invention is designed to operate the numerous electrodes individually and sequentially. Experimentallyg it has been verified that about 30 to 40 excitations/second no perceptual changes are felt at threshold level, whereas above threshold levels~ a few subjects perceive the difference between 40 and 80 Hz and none over 80 Hz.
; At the low battery voltage it can take as long as 2 milliseconds to store the maximum energy. The clocking system must insure against more than one generator operating together and, in accordance with the present invention, the clock is automatically inhibited untll the last generator in the chain of generators has delivered its energy.
In addition, it has also been found that as time passes, there is a decreasing sensory perception, or acclimitization, at constant energy. An "anti-adapt" system has been devised to avoid this. While lt is not necessary to "feel" the stimulations for ; effectiveness, there is a tendency for the therapist~ as well as the patient, to require some sort of a sensory effect. Based on the fact that step changes in energy of a few percent can be fclt, a system of clock modulation was devised which stops excitation approximately 10% of the time of a 1/2 to 2 second base when thc 7J~7~ "Anti-adapt" ls "on" and about 10~ ms Or a 20 second base when it is "off".
This "anti-adapt" system is also useful to determine defective energy generators since the chain stops in the absence of a trigger pulse to the next generator so that the last gener~tor never signals the clock to operate the first generator and the energy absorption sensor (described more fully hereinafter) i~--~ 9~lZ
indicates that the stage has failed~
The upper portion of Fig~ 1 shows the Clocking System and the Anti-adapt System. The central chassis circuitry consists of two multi-vibrators ICl and IC3 (compr~sing IC4011) and is a standard and well kno~Jn CMOS quad NAND gate ~!hich is available from a number of manufacturers. In general, the clocking system consists of a multi-vibrator ICl ~ade up Or gates I and II with pins 1~ 2 and 3 and 4, 5 and 6, res~ectively.
This multi-vibrator may be a well known RCA multi-vibrator in which a diode Dl is used to create an asymmetric clock. ~ased on the position of switch Sl, the output repetition rate is 50 or 80 Hz at pin 4. If desired9 Sl may be replaced by a potentiometer and a fixed resistor to permit the clock to be variable rather than preset.
It is also possible to substitute for the 2 leg NAND gate of the clock ICl, the equivalent function of a 2 leg NAND Schmitt trigger, which is also of CMOS construction. The internal regenerative action of the Schmitt trigger reduces battery drain because of reduction in the time during which the series transistors in the output Or the gates can conduct from the power supply to common. This ~lould reduce the load on the batteriesO
Pins 2 and 6 of multi-vibrator ICl connect together to the output of an antiadapt multi-vibrator IC3 having gates I and II with pins 7 to 10 and 11 to 14, respect~vely. The antiadapt multi-vibrator IC3 has a s~litch S2 ~hich modulates the clock. If S2 is in the "on" position, the main clock output of pin 4 is inhibited for approxim2tely 100 milliseconds out Or every second. If S2 is in the "off" position, the multi-vibrator ICl operates more slo.lly and is considerably more asy~etric, i.e.
the output of pin 4 is inhibited about 10 ~illiseconds out Or 3o ~pproximately every 10-20 seconds. The frequency is controlled .
by capacltors C2 and C3, which are identical, with the effective capacitance being halved by the series connection. If electrolytic capacitors are used at C2 and C3~ resistor R13 is provided to prevent reverse bias. If monolytic capacitors are to be used, the capacitor C2 may be replaced by a short circuit and resistor R13 is eliminated so that only C3 remains.
Pins 13 and 9 are interconnected so that when the instru~ent is turned on, and receives power from the batteries Bl-B4, pin 13 rises with the power switch output at 3, but pin 9 is delayedc Pin 9 is allo~Jed to rise with a time constant which is a product of resistor R12 and capacitor C5~ With pin 9 remaining at ground potential lohger than pin 13, the output 10 of gate I
is held at a "1" and with pin 13 of gate II also at "1"~ the multi-vibrator is inhibited. The output on pin 11 is held at "0"
until pin 9 rises to "1" at which time the multi-vibrator IC3 is released. Pin 11 is a R~SET to all the energy generatorsO Hence, the energy generators are conditioned to be in the "offl' position when the instrument is turned on. American Association for Medical Instrumentation Regulations suggest a long turn-on delay for instruments without switches on outputs. The time constant R12 C5 generates approximately a 15 second delay to conform to ` the requirements.
The clock output pin 4 of ICl enters a trigger circuit IC2 which is a separate C2~0S integrated circuit and which may be a triple NA~ gate type 4023. This trigger circuit comprises a flip-flop with pins 10, 11, 12 and 13 on gate I and pins 1, 2, 8 and 9 on gate II. The clock output at 4 comes in while pin 10 of gate I is in the "1" condition, at ~Ihich time pin 9 of gate II, which has been in the "1" condition, goes to "0". R6 and C4 is a delay circuit which pernits a brief pulse of about 15 microseconds I
. .
2~ 2 ~ .
to issue from pin 6 of gate III. The output on pin 10 remains at a "1" and pin 9 remains at "0" until either a DONE IN signal arrives at pin 8 of gate II or a RESET occurs on pins 2 of gate II and 3 of gate III. At that time, the clock output 4 operates on pin 12 of gate I. The RESET causes pin 4 to be in the "1"
condition while pin 11 is in the "0" condition so that no TRIG
OUT occurs during RESET of the energy generator.
Referrring to Fig~ 2, the DONE IN signal is a competion signal from the last connected energy generator. Each energy generator chassis consists of a number of generators. In the present application, six generators are used so that there are six identical boards interconnected to a mother board which has a control transistor Q5 ~2N5172). The connector which permits the control chassis to power the energy generator chassis has five active pins in the interconnecting connector while the connector which permits subsequent energy generators to ~e connected consist of six pins (see additional DISABLE pin).
As shown in Fig. 3, if an additional energy generator chassis is plugged into the first energy generator chassis, the control transistor Q5 is inhibited (see DISABLE on its base) from operating because no output exists on the common DONE IN
line. It is only the last stage of the last chassis which drives the control transistor Q5 so that while there are as many Q5 transistors as there are generator chassis, only the last one will be permitted to operate.
If the DONE IN signal does not arrive between successive clock pulses, no TRIG OUT signal from pin 6 (Fig. 1) will arise until a DONE IN occurs so that the clock rate is, in effect, divided by two, if the time required to operate all the energy generators results in a DONE IN signal arriving after the second clock pulse and before the third. It is also possible to release the clock immediately upon receipt of a DONE IN signal X
_ g _ 90~2 if a cl~ck pulse has been missedD
In connection with the energy generator of the p~esent invention, the energy is stored inductivelyO An inductance Tl (Fig. 2) is used in each of the energy generators, the secondary winding of which is connected to the electrodes.
In general, energy may be stored either inductively or capacitativelyO Capacitative storage of energy is not desirable in a system whose outputs must be isolated from each other because the energy must be delivered through a transformer or some other isolator. In addition, capacitor voltages are high and trans~ormer failure may result in dangerous situations.
However, inductor storage of energy is possible ~rom a relatively low supply voltage. The energy stored is 1/2 LI2, lf L
is in henries and I is in amperes, the energy is in watt-seconds.
LI
The time T required to attain a given current is T - V where the resistance of the inductor is negligible, V is the effective supply voltage, I is the current, L is the inductance and T is in seconds.
It has been experimentally determined that energies between 10-6 and 2xlO 4 watt-seconds, which, respectively, correspond to subsensory and painful forced muscle cont~ ction, were desirabie. The energy is created by storage on a 25 t 5 millihenry inductor Tl which is formed by winding 225 turns of #34 wire on 1/2 of the bobbin of an 18mm Dia ferrite pot core hav~ng an AL f 630. This particular ferrite core is able to store the maximum energy only ~ust prior to saturation so that there is no possibility that the inductor can deliver much more than the maximum energy desire~.
Operating room conditions demand the use of no more than about 6 volts without danger. In order to avoid the problem of possible transformer breakdown and because of portability - .
considerations, the present invention uses a battery operated instrument. Batteries change their voltage as a function of residual capacity, so that a series connection of four fully chargecl Ni Cd batteries initially deliver about 5.64 volts (5-10% capacity used), about 5 volts most of the time (80~
capacity) and rapidly discharge to 0 in the last 10~ of capacityO
In order to achieve the maximum interval between battery recharge it is necessary to regulate the energy since a change from ~o64 to for example, 3.5 volts would lead to a decreased storage 10 energy of 37.8~ as the battery output decayedO The energy may _-be regulated by controlling either the ef~ective battery voltage, controlling the time of com~ection of the inductor to the battery or controlling the current in the inductor. The control must be e~fective over the entire energy range and for the inductor Tl is from approximately 5 to 100 milliamperes. The lnductor should have no energy stored except prior to release so that the energy must be ~witched in such a way that only one Or a series of generators, each of which provide their isolated output to a pair of electrodes, can be activated at one time.
~20 ~ecause of the large number of generators contemplated, _ each with the two electrodes, the invention includes a method of determining the amount of energy not absorbed by the electrodes.
The energy generators and absorption sensor of the present invention is shown in Fig. 2. The energy generator IC4 comprises gates NAND 1 and NAND 2 which make up a flip-flop with NAND 1 initially having its output in the "0" condition and NAND 2 having its output ln the ~ conditlon. Thus, transistors Ql and Q2 are held in the "off" condition since no base curren~ is avallable for Ql. Ql and Q2 are preferably a Darlington pair modified by Dl which bridges the emitter-base of Ql and is used I
~3 ~ l~g~l~
t~ accelerate shu~-off of Q2. ,Ihen a clock pul~e arrives, the output Or NAND 1 raises and Ql and Q2 saturate since the collectors cannot obtain sufficient cur~ nt from the inductor.
The voltage on the collector side of the inductor falls almost to common and re~ains in this condition until point C, the waveform of ~:hich i~ shown in Fig. 6, or the voltage caused by the current through R4~ R5, is sufficient to turn on Q3O l~hen Q3 turns on, its collector stabilizes the base ~roltage o~ Ql so that the current in the inductor Tl can no longer increase. At this point, the collector voltage of Q3 rises abruptly to the supply voltage, which may be approximately ~5. This increase in voltage is noo communicated to NAND 3 through Cl by current through R6 because the junction of ClR6 is no longer clamped by D2.
R7, R8 and Cl make up a differentiator with R7 and R8 used to establish a DC bias level for the differentiator and its _ tlme constant. If the number of sta~es of energy ~eneration is large or there is no mother board, it is possible to save one resistor per energy generator at the cost of 2 resistors which are used to set a common bias level. To establish the differentiator reference level, the present design uses 2N
resistors, it is possible to use N+2 resistors where N is the number of energy generators.
The input leg of NAI~ 3 to Cl is normally biased 1/3 of the supply voltage above ground. When the voltage at point A
(the waveform of which is sho~n in Fig. 4) rises abruptly, because the other two legs of the gate I~AI~D 3 are in the "1" condition the output of NAI~D 3 falls to "0". This resets gate NAI~D 2 .~hich in turn alters the state of NAI~D 1 vi~ the connection between pins 6 and 11 end at the same ti~e eenerates an output which is preferably -~2 -;
::
F~
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the narrowest output pulse possible consistent with the given gate chain. NAND 3 not only resets the memory assembly of its own ~generator but also ~ sets the memory assembly of the next ~ generator. In the last generator, however, NAND 3 causes Q5 to activate a DONE IN signal, as well as reset its own memory.
The connection between the output of NAND 1 and one - of the input legs of NAND 3 guarantees an output pulse width of two propagation delay times, onl~ one of which is required ~or the next energy generator. Thus the output from NAND 3 iæ a fairly narrow pulse (approximately 400 NS) guaranteed to be wide enough to operate the next stage and at the same time narrow enough to prevent a signal other than the valid one from being pulsed from the output of NAND 3. This is important since subsequent electrodes, or subsequent energy generators can, if the electrodes from a previous generator are geometrically disposed, permit current to pass through the output winding of a previous stage. If the differentiator were not gated then a false trigger signal could be supplied. Because of the interconnection of NAND 1 and NAND 3 there is no possible method of generating a false trigger signal.
When NAMD 1 and NAND 2 are altered by NAND 3 the output Or NAND 2 forces Q3 into heavy conduction by reason Or the capacitor C2. This quickly shuts Orr Ql directly and Q2 via Dl.
The shut-off is rapid enough 80 the energy that was stored in the inductor Tl cannot dissipate through Ql, Q2. It must ; dissipate either through D3 and D6, in which case LED D6 will illuminate, or through the secondary winding Or Tl through D4 to the external electrodes.
If the external electrodes are properly connected, then the voltage at A will not rise enough to pass current throu6h D6 since the voltage required is the voltage necessary to pass current through D7, D8 and D9 on the mother board. D7, D8 and . D9, Q4 and R9 form a power zener diode, or a low lmpedance zener ,~........... . . . . . .
29~)12 diode. The diodes, are normally 33 volt zeners, having an accumulated su~ of about 100 volts. If the voltage on the collector of Ql, Q2 exceeds 100 volts current passes through D6 and the LED lights up. If the energy does not pass through D5 then it must have passed out the secondary winding f ~1-If for any reason Q3 fails in the open condition thecircuit ~ill continue to operate. The current r-Lses in the inductor and when it reaches core saturation the inductance i~ falls very rapidly and voltage can no longer be supported across the core winding since the inductance falls to llo" or very close to "O". Under this situation a pulse is still delivered to the gated different~ tor and a subsequent trigger to the succeding stage, however, since the inductor Tl has been chosen to saturate at slightly more than the maximum energy, an unsafe condition does not exist. Under every other situaffDn of failure, 1.e. Q3 failing as a short, the generator fails to do anything and no trigger pulse is generated fro~ the gated differentiator an~ the firing for the remainder of the chain is halted until a RESET occurs. The energy generators-will fire sequentially during failure up to the failed stage and no further, therefore it is possible with the electrodes disconnected to examine the light pattern from D6 LED~ and determine the last stage to operate. The stage following that is defective.
Capacitor C2 speeds up the shut-off of Ql, Q2 which is important at the lower currents. At the ~aximum value of R5, very little energy is placed on the primary of Tl and if Ql, Q2 do not shut off rapidly then the ener6y stored in the inductor T
will be lost to Ql, Q2 during shut-off.
; Another function of C2 is to stabilize the current regulating loop. The output Or I~h~D 2 is ne2r either co~on or '.
. i %
the positive supply by reason of the nature of the CMOS
integrated circuit, the effective series resistance of about 500 ohms is considered almost negligible. The current regulator (Ql, Q2, Q3 and associated parts) is effective, restricting changes in output energy to approximately 5% for a supply voltage swing of 3-l/2 to 10 or 12 volts. The diode D5 is a germanium or Shottky diode whose purpose is to temperature compensate the regulator loop, including the ferrite core of Tl. D4 restricts the direction of energy delivery and this restriction is associated with the absence of any unpleasant sensations under the electrodes.
The regulator arrangement permits delivery of constant watt-seconds per pulse to pairs of electrodes, independent of the state of the battery supply (as long as there is sufficient voltage for the circuit to operate at all). The energy is stored in the ferrite core Tl by controlling the flux density in the core which is done by the primary winding connected to the feed back current regulator which will turn itself off when the current commanded by the adjustable potentiometer (R5) has been reached. The energy (l/2 LI2) is inhibited from leaving via the current regulator loop because it ceases to be able to conduct after it is satisfied. The energy in the core Tl is free to leave by one of two alternative paths, i.e. through a secondary winding to the tissue-electrode system or via the primary alternate absorption system of D3, D6, D7, D8, D9, R9 and Q4. The secondary winding is isolated from the tissue during energy storage by a series diode D4. The voltage across electrodes in good contact with the skin does not exceed 30 to 40 volts maximum when 100 milliamperes flows. If the voltage across the electrodes does not exceed acceptable values, e.g.
approximately 90 volts, all the energy is sent to the tissue-electrode system. If it is in excess of gn volts ~9~)~2 the electrode contact 15 not good and the energy 18 released to both the electrode tissue system and through LED D6. Th~t portlon of the energy whlch passes through the LED D6 illuminates it, thereby alerting the therapist that the electrodes assoclated with that particular energy generator are in poor contact. The brighter the LED the poorer the electrode contact wlth no connectlon caus~ng the brightest conditions.
The present invention also envlsion~ the use of a battery ~aver if large numbers Or energy generators are connected but only a few are used. Energy stored on the inductor but not delivered to the electrodes can be returned to the battery. A third wlnding would be incorporated on the core bobbin and the LED absorption sensor system moved to the additional windlng. In order to be effective an energy spreader, consisting Or a capacitor and a transistor as well as re~istors, is used to meter the returned energy slowly in co~parison to its availability since the battery electrochemical characteristics will not permit recharge by extremely short pulses.
This battery saver fe~ture with an energy spreader . . .
- 20 is illustrated in Figs. 7 and 8.
Figure 7 ls a diagrammatic simplified version Or the energy generator shown in Fig. 2 which has been described above and which has an indicator circuit whlch illuminates an LED D6 if the energy available from the inductor Tl is not absorbed by the load at a voltage lower than the zener breakdown voltage of zener diodes D7-D9. m e effective zener breakdown voltage consists of Vz + Vled + Vdiode, where Vled + Vdiode are the foreward voltage drops across these elements.
; When transistors Ql and Q2 are turned off, the energy in Tl is 1/2LI2, where I i6 the current in the inductor . ~
. .
s , ' .
~29~
at the time the transistors are turned off. At this ti~e, the energy is dissipated in either the external electrodes or in the indicator circuitry or the transistor circuit. Vz effective must ble chosen so that the transistor breakdown ls not an available energy sink. For that interval that IZload> OR = Vz effective, the energy is discharged into both the external electrodes and the indicator circuitry. ~hen there is no external load, all the energy is absorbed by the indicator circuitry and would ordinarily be wasted. However, the energy ; 10 not absorbed by the external load may be conserved, i.e.
returned to a rechargeable battery B provided that the form - in which the energy is retuLrned is compatible to its acceptance by the electrochemical system that makes up the battery B.
To be compatible the recharge voltage must be greater than that of the battery and the charge must be distributed in time for an interval which is long compared ~lith the time re~uired to satisfy the electrochemical requirements associated ~ith recharge. In the present structure, the duration for direct energy recovery from the condition occuring with an open circuit -~20 no load situation at the output is too short. The electrochemicalsystem will not, for instance, recognize sub-microsecond and microsecond energy pulses as being suitable for charge recovery.
In order to make the energy recoverable it must be stored and fed back to the battery more slowly.
. 2 shows a circuit for spreading the energy and recharging a battery. This may be the original batteries Bl-B4 used to supply po-ler to the unit or it may be a separate battery.
Instead of being returned to co~on, t~e zener diodes D7-D9 are ! returned to a capacltor C4 which is connected to the battery B
throu~n an inductor T2. The inductance of T2 is large enough so that essentially no current flo.Js through lt for short term changes on C4. The voltage cn C4 ls essentlally ~/7 -.. -~
B
, ~ lZ9~12 Vb. Tne energy that was in Tl will, if it does not exit through the external load, find its way onto C4 (neglecting resistive losses associated with Va, Vd, & Vled)0 This will result in a voltage increase ~ V) on C4 such that ~ V = I(L/C) 1/2. The incremental voltage will lead to a current (whose driving voltage is ~ V-Vd) ~hich is slo~11y metered into the battery B
by the impedance of the inductor T2.
The use o~ the resistor R10 across the diode D10 permits the energy to be placed on C4 from voltage Vb. m e metering time consists of the size of C4 and T2 and depends on the interval between energy availabilities from Tl as well as the restrictions of the electrochemical system. Storing the energy on C4 increases the effective peak zener voltage by a V. Vz effective=Vz+Vd+Vled+Vb and the sum must be less than the collector to emitter breakdown voltage of the transistors Ql-Q2. A lower value of Vz may require selection of zener diodes having a lower breakdown potentialO
It will thus be seen that the present invention provides an improved transcutaneous pain reliever having multiple electrode ~20 pairs to increase the area Or stimulation while at the same time keeping the current density constant without any danger to the patient because of increased voltage or any conceivable failure mode. The invention also provides for an improved energy generator in ~hich energy is stored inductively with an improved electrode energy absorption sensor to determine actual energy not absorbed by the electrodes and provides an improved clocking system in which the var~ous electrodes are not fired together but sequentially activated. The invention ~urther provides an "antiadapt" system ln order to prevent the patient ~ro~ becoming acclimated to the sensations and includes the use of an improved battery saver so that -/~ .
, ~
nergy not delivered can be returned to the batteries. The battery charger used with the present invention is trans-formerless and is zener bridged to permit the use of signal diodes for charging purposes and which is automatically dis-connected when being charged.
Thus the present invention provides an improved transcutaneous pain reliever in which the circuitry is such that there is no danger of the various electrodes firing together.
It also provides an improved transcutaneous pain reliever which is unable to cause injury in any conceivable failure mode.
The present invention further provides an improved transcutaneous pain reliever in which the energy generators use inductively stored energy, and an improved transcutaneous pain reliever in which an electrode energy absorption sensor is provided in order to determine actual energy not absorbed by the electrodes.
The present invention also provides an improved transcutaneous pain reliever which uses an improved clocking system for energizing the various electrodes individually with the clocking system devised so that more than one generator cannot operate at the same time.
Further the present invention provides an improved transcutaneous pain reliever which incorporates therein an "antiadapt" system in order to prevent the patient from becoming acclimated to the electrical impulses.
It also provides an improved transcutaneous pain reliever in which a transformerless, bridged battery charger is used to permit inexpensive low power low voltage signal diodes to be used independent of the magnitude of a much higher charging ,. --2~
~29~1Z
vo:Ltage source.
In addition, the present invention provides animproved transcutaneous pain reliever in which the battery charger is automatically mechanically disconnected from the main patient connectable circuitry when it is charging.
It also provides an improved transcutaneous pain reliever in which a battery saver is provided so that excess energy not delivered to electrodes can be returned to the batteries.
As many and varied modifications of the subject matter of this invention will become apparent to those skilled in the art from the detailed description given hereinabove, it will be understood that the present invention is limited only as p~ovided in the claims appended hereto.
: I
-~0~
the pulsing of the current to a succeeding one of the electrode assemblies.
A preferred embodiment of the invention has been chosen for purposes of illustration and description and is shown in the accompanying drawings forming a part of the specification, wherein:
Figure 1 is a schematic view showing the circuitry of the battery charger, the clocXing system and the anti-adapt system used in accordance with the present invention.
Figure 2 is a schematic view showing an energy generator of the present invention with the lower part showing the parts in block diagram form, the central part showing the recommended values for the parts and the upper part showing the parts used.
Figure 3 is a schematic diagram showing the circuitry between the control connectors and the energy generators.
Figure 4, 5 and 6, which appear on the same sheet as Figure 1, show the waveforms generated at points A, B and C, of Figure 2.
Figure 7 is a diagramatic view of a simplified version of the energy generator as shown in Figure 2.
Figure 8 is a view similar to Figure 7 showing the use f a B
0~L2 battery saver energy spreader circuitu The battery charger of the present invention is shown schematically in ~ig. 1. The power for the instrument is obtained from a plurality or chain Or batteries Bl to ~40 A switch S3 controls the battery chain connections between CHARGE, OFF and ON.
The charger unit is a brldged, transformerless bridge rectifier unit which permits the use o~ low voltage inexpensive diodes (such as 25 V PIV,) on a 230 volt line. The battery charger comprises diodes D3, D4, D5 and D6 which are arranged as a bridge. A zener diode D8 is used across the output of the bridge. 2ener diode D8 permits the batteries Bl to B4 to be disconnected ~rom the bridge without subjecting the bridge diodes to large inverse voltages. The voltage passing zener D8 is no larger than the breakdown voltage of zener D8 so that the zener diode D8 protects the low voltage bridge diodes D3 to D6 when the battery is disconnected from the charger and the charging circuit ls still receiving power from the main power line.
Since the voltage of zener D8 is greater than the battery voltage, the zener D8 has no effect when the batteries Bl-B4 are connected to the charger by switch S3. However, if the batteries Bl-B4 are disconnected from the charger, the zener D8 absorbs the charging current while insuring that the maximum voltage across the bridge diodes D3-D6 is only slightly greater ; than it would have been with the batteriesin place. Thus, even though the charging voltage supply is very high, the bridge diodes D3-D6 require a rating only slightly greater than that of the zener diode voltage of D8 which in turn is only slightly greater than the battery voltage.
The voltage Or the zener diode D8 depends upon the i 3 battery requirements and, in the example illustrated, is preferably B
between 10 and 15 voltsO The batteries Bl-B4 are 150 milliampere-hour batteries which may be recharged at 15 milliamperes~
Preferably, they are nickel cadmium batteries of about 1.41 volts approximately, so that the battery chain total is 5.64 voltsO The LED D9 requires about 1 o6 volts and the reverse voltage protection diode D7 requires about 0~7 volts. Hence, breakdown voltage of .
zener diode D8 is such that no current passes through it when the battery assembly Bl B4 is c~nnected to the bridge D3-D6 by switch S3 .
being in the CHARGE position~ Under such circumstances, the 10 voltage from D7 to the cathode of zener D8 is approximately 8 .
volts so that if D8 is of greater voltagej e.gO about 10 volts, .
no current passesO
When the switch S3 is not in the CHARGE position but .
in the OFF or the ON positions, the output of the bridge D3-D6 is absorbed by zener diode D8. The current is limited by the resistors R15 and R16 to about 15 milliamperes under either 230 volt or the 115 volt depending upon the position of switch S4, some contacts o~ which are not used as a switch but rather as a set of points on which to mount the resistor R16. The inclusion ~20 of zener D8 across the bridge D3-D6 with the accompanying volta~e dropping resistors prevents the diodes in bridge D3-D6 from being subjected to any voltage greater than the breakdown voltage of the zener diode D8 in all positions o~ battery switch S3.
The energy generator chassis circuitry is incorporated ~ in a circuit separate from the control chassis containing the : batteries so that the physical interconnection of the two circuits makes it impossible to recharge the batterles while they are connected to the energy chassis. Hence, there can be no physical connection between the main po~er line and the person undergoing treat.~.ent ~Jhile the batteries are being charged since the batteries I
, ~12~0~;~
must be separated from the control chassis before they are - charged.
The improved clocking system Or the present invention is designed to operate the numerous electrodes individually and sequentially. Experimentallyg it has been verified that about 30 to 40 excitations/second no perceptual changes are felt at threshold level, whereas above threshold levels~ a few subjects perceive the difference between 40 and 80 Hz and none over 80 Hz.
; At the low battery voltage it can take as long as 2 milliseconds to store the maximum energy. The clocking system must insure against more than one generator operating together and, in accordance with the present invention, the clock is automatically inhibited untll the last generator in the chain of generators has delivered its energy.
In addition, it has also been found that as time passes, there is a decreasing sensory perception, or acclimitization, at constant energy. An "anti-adapt" system has been devised to avoid this. While lt is not necessary to "feel" the stimulations for ; effectiveness, there is a tendency for the therapist~ as well as the patient, to require some sort of a sensory effect. Based on the fact that step changes in energy of a few percent can be fclt, a system of clock modulation was devised which stops excitation approximately 10% of the time of a 1/2 to 2 second base when thc 7J~7~ "Anti-adapt" ls "on" and about 10~ ms Or a 20 second base when it is "off".
This "anti-adapt" system is also useful to determine defective energy generators since the chain stops in the absence of a trigger pulse to the next generator so that the last gener~tor never signals the clock to operate the first generator and the energy absorption sensor (described more fully hereinafter) i~--~ 9~lZ
indicates that the stage has failed~
The upper portion of Fig~ 1 shows the Clocking System and the Anti-adapt System. The central chassis circuitry consists of two multi-vibrators ICl and IC3 (compr~sing IC4011) and is a standard and well kno~Jn CMOS quad NAND gate ~!hich is available from a number of manufacturers. In general, the clocking system consists of a multi-vibrator ICl ~ade up Or gates I and II with pins 1~ 2 and 3 and 4, 5 and 6, res~ectively.
This multi-vibrator may be a well known RCA multi-vibrator in which a diode Dl is used to create an asymmetric clock. ~ased on the position of switch Sl, the output repetition rate is 50 or 80 Hz at pin 4. If desired9 Sl may be replaced by a potentiometer and a fixed resistor to permit the clock to be variable rather than preset.
It is also possible to substitute for the 2 leg NAND gate of the clock ICl, the equivalent function of a 2 leg NAND Schmitt trigger, which is also of CMOS construction. The internal regenerative action of the Schmitt trigger reduces battery drain because of reduction in the time during which the series transistors in the output Or the gates can conduct from the power supply to common. This ~lould reduce the load on the batteriesO
Pins 2 and 6 of multi-vibrator ICl connect together to the output of an antiadapt multi-vibrator IC3 having gates I and II with pins 7 to 10 and 11 to 14, respect~vely. The antiadapt multi-vibrator IC3 has a s~litch S2 ~hich modulates the clock. If S2 is in the "on" position, the main clock output of pin 4 is inhibited for approxim2tely 100 milliseconds out Or every second. If S2 is in the "off" position, the multi-vibrator ICl operates more slo.lly and is considerably more asy~etric, i.e.
the output of pin 4 is inhibited about 10 ~illiseconds out Or 3o ~pproximately every 10-20 seconds. The frequency is controlled .
by capacltors C2 and C3, which are identical, with the effective capacitance being halved by the series connection. If electrolytic capacitors are used at C2 and C3~ resistor R13 is provided to prevent reverse bias. If monolytic capacitors are to be used, the capacitor C2 may be replaced by a short circuit and resistor R13 is eliminated so that only C3 remains.
Pins 13 and 9 are interconnected so that when the instru~ent is turned on, and receives power from the batteries Bl-B4, pin 13 rises with the power switch output at 3, but pin 9 is delayedc Pin 9 is allo~Jed to rise with a time constant which is a product of resistor R12 and capacitor C5~ With pin 9 remaining at ground potential lohger than pin 13, the output 10 of gate I
is held at a "1" and with pin 13 of gate II also at "1"~ the multi-vibrator is inhibited. The output on pin 11 is held at "0"
until pin 9 rises to "1" at which time the multi-vibrator IC3 is released. Pin 11 is a R~SET to all the energy generatorsO Hence, the energy generators are conditioned to be in the "offl' position when the instrument is turned on. American Association for Medical Instrumentation Regulations suggest a long turn-on delay for instruments without switches on outputs. The time constant R12 C5 generates approximately a 15 second delay to conform to ` the requirements.
The clock output pin 4 of ICl enters a trigger circuit IC2 which is a separate C2~0S integrated circuit and which may be a triple NA~ gate type 4023. This trigger circuit comprises a flip-flop with pins 10, 11, 12 and 13 on gate I and pins 1, 2, 8 and 9 on gate II. The clock output at 4 comes in while pin 10 of gate I is in the "1" condition, at ~Ihich time pin 9 of gate II, which has been in the "1" condition, goes to "0". R6 and C4 is a delay circuit which pernits a brief pulse of about 15 microseconds I
. .
2~ 2 ~ .
to issue from pin 6 of gate III. The output on pin 10 remains at a "1" and pin 9 remains at "0" until either a DONE IN signal arrives at pin 8 of gate II or a RESET occurs on pins 2 of gate II and 3 of gate III. At that time, the clock output 4 operates on pin 12 of gate I. The RESET causes pin 4 to be in the "1"
condition while pin 11 is in the "0" condition so that no TRIG
OUT occurs during RESET of the energy generator.
Referrring to Fig~ 2, the DONE IN signal is a competion signal from the last connected energy generator. Each energy generator chassis consists of a number of generators. In the present application, six generators are used so that there are six identical boards interconnected to a mother board which has a control transistor Q5 ~2N5172). The connector which permits the control chassis to power the energy generator chassis has five active pins in the interconnecting connector while the connector which permits subsequent energy generators to ~e connected consist of six pins (see additional DISABLE pin).
As shown in Fig. 3, if an additional energy generator chassis is plugged into the first energy generator chassis, the control transistor Q5 is inhibited (see DISABLE on its base) from operating because no output exists on the common DONE IN
line. It is only the last stage of the last chassis which drives the control transistor Q5 so that while there are as many Q5 transistors as there are generator chassis, only the last one will be permitted to operate.
If the DONE IN signal does not arrive between successive clock pulses, no TRIG OUT signal from pin 6 (Fig. 1) will arise until a DONE IN occurs so that the clock rate is, in effect, divided by two, if the time required to operate all the energy generators results in a DONE IN signal arriving after the second clock pulse and before the third. It is also possible to release the clock immediately upon receipt of a DONE IN signal X
_ g _ 90~2 if a cl~ck pulse has been missedD
In connection with the energy generator of the p~esent invention, the energy is stored inductivelyO An inductance Tl (Fig. 2) is used in each of the energy generators, the secondary winding of which is connected to the electrodes.
In general, energy may be stored either inductively or capacitativelyO Capacitative storage of energy is not desirable in a system whose outputs must be isolated from each other because the energy must be delivered through a transformer or some other isolator. In addition, capacitor voltages are high and trans~ormer failure may result in dangerous situations.
However, inductor storage of energy is possible ~rom a relatively low supply voltage. The energy stored is 1/2 LI2, lf L
is in henries and I is in amperes, the energy is in watt-seconds.
LI
The time T required to attain a given current is T - V where the resistance of the inductor is negligible, V is the effective supply voltage, I is the current, L is the inductance and T is in seconds.
It has been experimentally determined that energies between 10-6 and 2xlO 4 watt-seconds, which, respectively, correspond to subsensory and painful forced muscle cont~ ction, were desirabie. The energy is created by storage on a 25 t 5 millihenry inductor Tl which is formed by winding 225 turns of #34 wire on 1/2 of the bobbin of an 18mm Dia ferrite pot core hav~ng an AL f 630. This particular ferrite core is able to store the maximum energy only ~ust prior to saturation so that there is no possibility that the inductor can deliver much more than the maximum energy desire~.
Operating room conditions demand the use of no more than about 6 volts without danger. In order to avoid the problem of possible transformer breakdown and because of portability - .
considerations, the present invention uses a battery operated instrument. Batteries change their voltage as a function of residual capacity, so that a series connection of four fully chargecl Ni Cd batteries initially deliver about 5.64 volts (5-10% capacity used), about 5 volts most of the time (80~
capacity) and rapidly discharge to 0 in the last 10~ of capacityO
In order to achieve the maximum interval between battery recharge it is necessary to regulate the energy since a change from ~o64 to for example, 3.5 volts would lead to a decreased storage 10 energy of 37.8~ as the battery output decayedO The energy may _-be regulated by controlling either the ef~ective battery voltage, controlling the time of com~ection of the inductor to the battery or controlling the current in the inductor. The control must be e~fective over the entire energy range and for the inductor Tl is from approximately 5 to 100 milliamperes. The lnductor should have no energy stored except prior to release so that the energy must be ~witched in such a way that only one Or a series of generators, each of which provide their isolated output to a pair of electrodes, can be activated at one time.
~20 ~ecause of the large number of generators contemplated, _ each with the two electrodes, the invention includes a method of determining the amount of energy not absorbed by the electrodes.
The energy generators and absorption sensor of the present invention is shown in Fig. 2. The energy generator IC4 comprises gates NAND 1 and NAND 2 which make up a flip-flop with NAND 1 initially having its output in the "0" condition and NAND 2 having its output ln the ~ conditlon. Thus, transistors Ql and Q2 are held in the "off" condition since no base curren~ is avallable for Ql. Ql and Q2 are preferably a Darlington pair modified by Dl which bridges the emitter-base of Ql and is used I
~3 ~ l~g~l~
t~ accelerate shu~-off of Q2. ,Ihen a clock pul~e arrives, the output Or NAND 1 raises and Ql and Q2 saturate since the collectors cannot obtain sufficient cur~ nt from the inductor.
The voltage on the collector side of the inductor falls almost to common and re~ains in this condition until point C, the waveform of ~:hich i~ shown in Fig. 6, or the voltage caused by the current through R4~ R5, is sufficient to turn on Q3O l~hen Q3 turns on, its collector stabilizes the base ~roltage o~ Ql so that the current in the inductor Tl can no longer increase. At this point, the collector voltage of Q3 rises abruptly to the supply voltage, which may be approximately ~5. This increase in voltage is noo communicated to NAND 3 through Cl by current through R6 because the junction of ClR6 is no longer clamped by D2.
R7, R8 and Cl make up a differentiator with R7 and R8 used to establish a DC bias level for the differentiator and its _ tlme constant. If the number of sta~es of energy ~eneration is large or there is no mother board, it is possible to save one resistor per energy generator at the cost of 2 resistors which are used to set a common bias level. To establish the differentiator reference level, the present design uses 2N
resistors, it is possible to use N+2 resistors where N is the number of energy generators.
The input leg of NAI~ 3 to Cl is normally biased 1/3 of the supply voltage above ground. When the voltage at point A
(the waveform of which is sho~n in Fig. 4) rises abruptly, because the other two legs of the gate I~AI~D 3 are in the "1" condition the output of NAI~D 3 falls to "0". This resets gate NAI~D 2 .~hich in turn alters the state of NAI~D 1 vi~ the connection between pins 6 and 11 end at the same ti~e eenerates an output which is preferably -~2 -;
::
F~
, 9~
the narrowest output pulse possible consistent with the given gate chain. NAND 3 not only resets the memory assembly of its own ~generator but also ~ sets the memory assembly of the next ~ generator. In the last generator, however, NAND 3 causes Q5 to activate a DONE IN signal, as well as reset its own memory.
The connection between the output of NAND 1 and one - of the input legs of NAND 3 guarantees an output pulse width of two propagation delay times, onl~ one of which is required ~or the next energy generator. Thus the output from NAND 3 iæ a fairly narrow pulse (approximately 400 NS) guaranteed to be wide enough to operate the next stage and at the same time narrow enough to prevent a signal other than the valid one from being pulsed from the output of NAND 3. This is important since subsequent electrodes, or subsequent energy generators can, if the electrodes from a previous generator are geometrically disposed, permit current to pass through the output winding of a previous stage. If the differentiator were not gated then a false trigger signal could be supplied. Because of the interconnection of NAND 1 and NAND 3 there is no possible method of generating a false trigger signal.
When NAMD 1 and NAND 2 are altered by NAND 3 the output Or NAND 2 forces Q3 into heavy conduction by reason Or the capacitor C2. This quickly shuts Orr Ql directly and Q2 via Dl.
The shut-off is rapid enough 80 the energy that was stored in the inductor Tl cannot dissipate through Ql, Q2. It must ; dissipate either through D3 and D6, in which case LED D6 will illuminate, or through the secondary winding Or Tl through D4 to the external electrodes.
If the external electrodes are properly connected, then the voltage at A will not rise enough to pass current throu6h D6 since the voltage required is the voltage necessary to pass current through D7, D8 and D9 on the mother board. D7, D8 and . D9, Q4 and R9 form a power zener diode, or a low lmpedance zener ,~........... . . . . . .
29~)12 diode. The diodes, are normally 33 volt zeners, having an accumulated su~ of about 100 volts. If the voltage on the collector of Ql, Q2 exceeds 100 volts current passes through D6 and the LED lights up. If the energy does not pass through D5 then it must have passed out the secondary winding f ~1-If for any reason Q3 fails in the open condition thecircuit ~ill continue to operate. The current r-Lses in the inductor and when it reaches core saturation the inductance i~ falls very rapidly and voltage can no longer be supported across the core winding since the inductance falls to llo" or very close to "O". Under this situation a pulse is still delivered to the gated different~ tor and a subsequent trigger to the succeding stage, however, since the inductor Tl has been chosen to saturate at slightly more than the maximum energy, an unsafe condition does not exist. Under every other situaffDn of failure, 1.e. Q3 failing as a short, the generator fails to do anything and no trigger pulse is generated fro~ the gated differentiator an~ the firing for the remainder of the chain is halted until a RESET occurs. The energy generators-will fire sequentially during failure up to the failed stage and no further, therefore it is possible with the electrodes disconnected to examine the light pattern from D6 LED~ and determine the last stage to operate. The stage following that is defective.
Capacitor C2 speeds up the shut-off of Ql, Q2 which is important at the lower currents. At the ~aximum value of R5, very little energy is placed on the primary of Tl and if Ql, Q2 do not shut off rapidly then the ener6y stored in the inductor T
will be lost to Ql, Q2 during shut-off.
; Another function of C2 is to stabilize the current regulating loop. The output Or I~h~D 2 is ne2r either co~on or '.
. i %
the positive supply by reason of the nature of the CMOS
integrated circuit, the effective series resistance of about 500 ohms is considered almost negligible. The current regulator (Ql, Q2, Q3 and associated parts) is effective, restricting changes in output energy to approximately 5% for a supply voltage swing of 3-l/2 to 10 or 12 volts. The diode D5 is a germanium or Shottky diode whose purpose is to temperature compensate the regulator loop, including the ferrite core of Tl. D4 restricts the direction of energy delivery and this restriction is associated with the absence of any unpleasant sensations under the electrodes.
The regulator arrangement permits delivery of constant watt-seconds per pulse to pairs of electrodes, independent of the state of the battery supply (as long as there is sufficient voltage for the circuit to operate at all). The energy is stored in the ferrite core Tl by controlling the flux density in the core which is done by the primary winding connected to the feed back current regulator which will turn itself off when the current commanded by the adjustable potentiometer (R5) has been reached. The energy (l/2 LI2) is inhibited from leaving via the current regulator loop because it ceases to be able to conduct after it is satisfied. The energy in the core Tl is free to leave by one of two alternative paths, i.e. through a secondary winding to the tissue-electrode system or via the primary alternate absorption system of D3, D6, D7, D8, D9, R9 and Q4. The secondary winding is isolated from the tissue during energy storage by a series diode D4. The voltage across electrodes in good contact with the skin does not exceed 30 to 40 volts maximum when 100 milliamperes flows. If the voltage across the electrodes does not exceed acceptable values, e.g.
approximately 90 volts, all the energy is sent to the tissue-electrode system. If it is in excess of gn volts ~9~)~2 the electrode contact 15 not good and the energy 18 released to both the electrode tissue system and through LED D6. Th~t portlon of the energy whlch passes through the LED D6 illuminates it, thereby alerting the therapist that the electrodes assoclated with that particular energy generator are in poor contact. The brighter the LED the poorer the electrode contact wlth no connectlon caus~ng the brightest conditions.
The present invention also envlsion~ the use of a battery ~aver if large numbers Or energy generators are connected but only a few are used. Energy stored on the inductor but not delivered to the electrodes can be returned to the battery. A third wlnding would be incorporated on the core bobbin and the LED absorption sensor system moved to the additional windlng. In order to be effective an energy spreader, consisting Or a capacitor and a transistor as well as re~istors, is used to meter the returned energy slowly in co~parison to its availability since the battery electrochemical characteristics will not permit recharge by extremely short pulses.
This battery saver fe~ture with an energy spreader . . .
- 20 is illustrated in Figs. 7 and 8.
Figure 7 ls a diagrammatic simplified version Or the energy generator shown in Fig. 2 which has been described above and which has an indicator circuit whlch illuminates an LED D6 if the energy available from the inductor Tl is not absorbed by the load at a voltage lower than the zener breakdown voltage of zener diodes D7-D9. m e effective zener breakdown voltage consists of Vz + Vled + Vdiode, where Vled + Vdiode are the foreward voltage drops across these elements.
; When transistors Ql and Q2 are turned off, the energy in Tl is 1/2LI2, where I i6 the current in the inductor . ~
. .
s , ' .
~29~
at the time the transistors are turned off. At this ti~e, the energy is dissipated in either the external electrodes or in the indicator circuitry or the transistor circuit. Vz effective must ble chosen so that the transistor breakdown ls not an available energy sink. For that interval that IZload> OR = Vz effective, the energy is discharged into both the external electrodes and the indicator circuitry. ~hen there is no external load, all the energy is absorbed by the indicator circuitry and would ordinarily be wasted. However, the energy ; 10 not absorbed by the external load may be conserved, i.e.
returned to a rechargeable battery B provided that the form - in which the energy is retuLrned is compatible to its acceptance by the electrochemical system that makes up the battery B.
To be compatible the recharge voltage must be greater than that of the battery and the charge must be distributed in time for an interval which is long compared ~lith the time re~uired to satisfy the electrochemical requirements associated ~ith recharge. In the present structure, the duration for direct energy recovery from the condition occuring with an open circuit -~20 no load situation at the output is too short. The electrochemicalsystem will not, for instance, recognize sub-microsecond and microsecond energy pulses as being suitable for charge recovery.
In order to make the energy recoverable it must be stored and fed back to the battery more slowly.
. 2 shows a circuit for spreading the energy and recharging a battery. This may be the original batteries Bl-B4 used to supply po-ler to the unit or it may be a separate battery.
Instead of being returned to co~on, t~e zener diodes D7-D9 are ! returned to a capacltor C4 which is connected to the battery B
throu~n an inductor T2. The inductance of T2 is large enough so that essentially no current flo.Js through lt for short term changes on C4. The voltage cn C4 ls essentlally ~/7 -.. -~
B
, ~ lZ9~12 Vb. Tne energy that was in Tl will, if it does not exit through the external load, find its way onto C4 (neglecting resistive losses associated with Va, Vd, & Vled)0 This will result in a voltage increase ~ V) on C4 such that ~ V = I(L/C) 1/2. The incremental voltage will lead to a current (whose driving voltage is ~ V-Vd) ~hich is slo~11y metered into the battery B
by the impedance of the inductor T2.
The use o~ the resistor R10 across the diode D10 permits the energy to be placed on C4 from voltage Vb. m e metering time consists of the size of C4 and T2 and depends on the interval between energy availabilities from Tl as well as the restrictions of the electrochemical system. Storing the energy on C4 increases the effective peak zener voltage by a V. Vz effective=Vz+Vd+Vled+Vb and the sum must be less than the collector to emitter breakdown voltage of the transistors Ql-Q2. A lower value of Vz may require selection of zener diodes having a lower breakdown potentialO
It will thus be seen that the present invention provides an improved transcutaneous pain reliever having multiple electrode ~20 pairs to increase the area Or stimulation while at the same time keeping the current density constant without any danger to the patient because of increased voltage or any conceivable failure mode. The invention also provides for an improved energy generator in ~hich energy is stored inductively with an improved electrode energy absorption sensor to determine actual energy not absorbed by the electrodes and provides an improved clocking system in which the var~ous electrodes are not fired together but sequentially activated. The invention ~urther provides an "antiadapt" system ln order to prevent the patient ~ro~ becoming acclimated to the sensations and includes the use of an improved battery saver so that -/~ .
, ~
nergy not delivered can be returned to the batteries. The battery charger used with the present invention is trans-formerless and is zener bridged to permit the use of signal diodes for charging purposes and which is automatically dis-connected when being charged.
Thus the present invention provides an improved transcutaneous pain reliever in which the circuitry is such that there is no danger of the various electrodes firing together.
It also provides an improved transcutaneous pain reliever which is unable to cause injury in any conceivable failure mode.
The present invention further provides an improved transcutaneous pain reliever in which the energy generators use inductively stored energy, and an improved transcutaneous pain reliever in which an electrode energy absorption sensor is provided in order to determine actual energy not absorbed by the electrodes.
The present invention also provides an improved transcutaneous pain reliever which uses an improved clocking system for energizing the various electrodes individually with the clocking system devised so that more than one generator cannot operate at the same time.
Further the present invention provides an improved transcutaneous pain reliever which incorporates therein an "antiadapt" system in order to prevent the patient from becoming acclimated to the electrical impulses.
It also provides an improved transcutaneous pain reliever in which a transformerless, bridged battery charger is used to permit inexpensive low power low voltage signal diodes to be used independent of the magnitude of a much higher charging ,. --2~
~29~1Z
vo:Ltage source.
In addition, the present invention provides animproved transcutaneous pain reliever in which the battery charger is automatically mechanically disconnected from the main patient connectable circuitry when it is charging.
It also provides an improved transcutaneous pain reliever in which a battery saver is provided so that excess energy not delivered to electrodes can be returned to the batteries.
As many and varied modifications of the subject matter of this invention will become apparent to those skilled in the art from the detailed description given hereinabove, it will be understood that the present invention is limited only as p~ovided in the claims appended hereto.
: I
-~0~
Claims (27)
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A transcutaneous pain reliever, comprising a plurality of external electrode assemblies for supplying electrical excitations to a patient, means for sequentially and individually pulsing current through said external electrode assemblies, means for interrupting the pulsing of the current through said external electrode assemblies and means responsive to the completion of a pulse from any one of said electrode assemblies to discontinue the interruption of the pulsing of the current to a succeeding one of said electrode assemblies.
2. A transcutaneous pain reliever as claimed in claim 1, wherein said current pulsing means comprise means for inductively storing energy and means for releasing said energy to electrodes.
3. A transcutaneous pain reliever as claimed in claim 1, wherein said current pulsing means include clocking assembly for controlling the pulsing of the external electrode assemblies.
4. A transcutaneous pain reliever as claimed in claim 1, wherein storage means are provided for storing energy before passage to the external electrode assemblies and an absorption sensing mechanism is in circuit with said storage means to indicate the amount of energy not used by the external electrodes.
5. A transcutaneous pain reliever as claimed in claim 1, including a battery charger comprising a bridge assembly having a plurality of diodes arranged in a bridge, said bridge assembly having means to permit batteries to be charged to be connected thereto, a zener diode assembly across the output of the bridge assembly, and means for connecting the bridge assembly to a charging voltage source, said zener diode assembly having a breakdown voltage greater than the battery voltage and the bridge diode assembly having a voltage rating greater than the zener diode breakdown voltage.
6. A transcutaneous pain reliever as claimed in claim 1, wherein an anti-adapt system is provided comprising a multi-vibrator, the multi-vibrator being connected to a clock assembly and including means for inhibiting the output of the clock assembly.
7. A transcutaneous pain reliever as claimed in claim 1, including a battery saver comprising a storage coil and a charge release coil, a zener diode assembly for an absorption sensor, said zener diode assembly having a capacitor for connection to a battery to be charged, and an additional inductor coil in circuit with the zener diode assembly whereby energy not used by the release coil will be supplied to the battery to charge it through the said additional inductor coil.
8. A transcutaneous pain reliever as claimed in claim 2, wherein the current pulsing means include clock assembly is provided for controlling the pulsing of the external electrode assemblies.
9. A transcutaneous pain reliever as claimed in claim 8, wherein storage means are provided for storing energy before passage to the external electrode assemblies and absorption sensing means are provided in circuit with said storage means to indicate the amount of energy not used by the external electrode assemblies.
10. A transcutaneous pain reliever as claimed in claim 9, including a battery charger comprising a bridge assembly having a plurality of diodes arranged in a bridge, said bridge assembly having means to permit batteries to be charged to be connected thereto, a zener diode assembly across the output of the bridge assembly, and means connecting the bridge assembly to a charging voltage source, said zener diode assembly having a breakdown voltage greater than the battery voltage and the bridge diode assembly having a voltage rating greater than the zener diode breakdown voltage.
11. A transcutaneous pain reliever as claimed in claim 10, wherein an anti-adapt system is provided comprising a multi-vibrator, the multi-vibrator being connected to a clock assembly and including means for inhibiting the output of the clock assembly.
12. A transcutaneous pain reliever as claimed in claim 11, including a battery saver comprising a storage coil, and a charge release coil, a zener diode assembly for an absorption sensor, said zener diode assembly having a capacitor for connection to a battery to be charged and an additional inductor coil in circuit with the zener diode assembly whereby energy not used by the release coil will be supplied to the battery to charge it through the said additional inductor coil.
13. A transcutaneous pain reliever as claimed in claim 2, wherein said pulse preventing means comprise control transistors respectively associated with said external electrode assemblies, said control transistors being inhibited when no output exists on a DONE IN line common to said plurality of control transistors.
14. A transcutaneous pain reliever as claimed in claim 13, wherein a trigger assembly is provided to pulse a signal through said external electrode assemblies, said trigger assembly being inoperative until a DONE IN signal from one of said control transistors is received by said trigger assembly.
15. A transcutaneous pain reliever as claimed in claim 14, wherein an energy generator assembly is interposed in circuit between each of said external electrode assemblies and said trigger assembly for activating a respective one of said control transistors.
16. A transcutaneous pain reliever as claimed in claim 15, wherein a memory assembly and a gated differentiator for supplying a pulse to said memory assembly are provided in said energy generator assembly.
17. A transcutaneous pain reliever as claimed in claim 16, wherein said energy generator assembly includes a current regulator circuit in circuit with a flip-flop assembly for controlling the release of energy from said inductive storage means.
18. A transcutaneous pain reliever as claimed in claim 17, wherein said current regulator circuit includes a darlington pair and a feedback transistor, said darlington pair having its collector load connected to the inductive storage means and being in circuit with a first gate of the flip-flop, the output of which is responsive to a pulse from the trigger circuit, energy stored in said inductive storage means being released when the current regulator is shut off.
19. A transcutaneous pain reliever as claimed in claim 18, wherein said inductive storage means comprises a storage winding for storing the energy and a release winding for releasing said energy to the external electrode assemblies.
20. A transcutaneous pain reliever as claimed in claim 13, wherein a symmetric clock assembly including a multi-vibrator and a diode is provided for operating said external electrode assemblies.
21. A transcutaneous pain reliever as claimed in claim 20, wherein a switch is provided in the clock assembly multi-vibrator to vary the repetition rate of an output of the clock assembly.
22. A transcutaneous pain reliever as claimed in claim 20, wherein a potentiometer and a fixed resistor are provided for varying the output of the clock.
23. A transcutaneous pain reliever as claimed in claim 22, wherein an anti-adapt system is provided comprising a multi-vibrator connected to the clock assembly and including means for inhibiting the output of said clock assembly, the inhibiting means comprising a switch in circuit with said anti-adapt multi-vibrator with associated resistors.
24. A transcutaneous pain reliever as claimed in claim 23, wherein said clock assembly is in circuit with a trigger circuit, said trigger circuit comprising a flip-flop and a TRIG
OUT gate.
OUT gate.
25. A transcutaneous pain reliever as claimed in claim 13, including a battery saver comprising a storage coil, and a charge release coil, a zener diode assembly for an absorption sensor, said zener diode assembly having a capacitor for connection to a battery to be charged and an additional inductor coil in circuit with the zener diode assembly whereby energy not used by the release coil will be supplied to the battery to charge it through the said additional inductor coil, switch means being provided for connecting the diode assembly to the battery and for connecting the battery to a respective one of the external electrode assemblies so that connections of the battery to said external electrode assembly automatically disconnects battery from the diode assembly and connection of battery to the diode assembly automatically disconnects the battery from said external electrode assembly.
26. A transcutaneous pain reliever as claimed in claim 25, wherein the anti-adapt system and the clock assembly are connected to the segment of the switch of the battery charger which is connected to said external electrode assembly.
27. A transcutaneous pain reliever as claimed in claim 26, wherein storage means are provided for storing energy before passage to the external electrode assemblies and absorption sensing means are provided in circuit with said storage means to indicate the amount of energy not used by the external electrode assemblies, the absorption sensing means comprising an LED for indicating an excessive electrode voltage and a diode interposed between said storage means and said LED.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US05/921,344 US4256116A (en) | 1978-07-03 | 1978-07-03 | Transcutaneous pain reliever |
| US921,344 | 1978-07-03 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1129012A true CA1129012A (en) | 1982-08-03 |
Family
ID=25445303
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA329,209A Expired CA1129012A (en) | 1978-07-03 | 1979-06-06 | Transcutaneous pain reliever |
Country Status (7)
| Country | Link |
|---|---|
| US (1) | US4256116A (en) |
| JP (1) | JPS5510991A (en) |
| CA (1) | CA1129012A (en) |
| DE (1) | DE2926861A1 (en) |
| FR (1) | FR2430239A1 (en) |
| GB (1) | GB2039742B (en) |
| SE (1) | SE7905744L (en) |
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-
1978
- 1978-07-03 US US05/921,344 patent/US4256116A/en not_active Expired - Lifetime
-
1979
- 1979-06-06 CA CA329,209A patent/CA1129012A/en not_active Expired
- 1979-07-02 SE SE7905744A patent/SE7905744L/en not_active Application Discontinuation
- 1979-07-02 FR FR7917130A patent/FR2430239A1/en active Granted
- 1979-07-03 GB GB7923022A patent/GB2039742B/en not_active Expired
- 1979-07-03 JP JP8354879A patent/JPS5510991A/en active Granted
- 1979-07-03 DE DE19792926861 patent/DE2926861A1/en not_active Ceased
Also Published As
| Publication number | Publication date |
|---|---|
| GB2039742A (en) | 1980-08-20 |
| GB2039742B (en) | 1983-05-05 |
| FR2430239A1 (en) | 1980-02-01 |
| SE7905744L (en) | 1980-01-04 |
| FR2430239B3 (en) | 1981-05-29 |
| DE2926861A1 (en) | 1980-01-24 |
| JPS6240030B2 (en) | 1987-08-26 |
| US4256116A (en) | 1981-03-17 |
| JPS5510991A (en) | 1980-01-25 |
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