US 2350797 A
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June 6, 1944. P. MORLAND El'AL.
MEANS FOR PRODUCING ELECTRIC IMPULSES Filed Sept. 3, 1941 IIVIENTOR Pans/v Menu/yo Jones/v A001. SM/TH Patented June 6, 1944 l MEANS FOR PRODUCING ELECTRIC IMPULSES Preben Morland, Gentofte, and Jorgen Adolph Smith, Copenhagen, Denmark; vested in the Alien Property Custodian Application September 3, 1941, Serial No. 409,384 In Denmark June 21, 1940 7 Claims.
The invention relates to an apparatus for treatment of nerves and muscles by means of electric impulses, especially for artificial innervation of 'muscles, for instance for therapeutic purposes. The apparatus according to the invention is especially adapted for use in the training of muscles.
For the above mentioned purpose, electric impulses are used the voltage curve of which may be monopolar, i. e. the voltage curve for each individual impulse is either entirely above or entirely below a voltage of repose which generally will be zero. Usually, however, the voltage curve will be dipolar, i. e. the voltage curve has one portionsituated on one side of the voltage of repose, and an adjoining portion situated on the opposite side thereof. In therapeutics, such impulses are frequently called monophase and diphase or else galvanic and faradic impulses, respectively. The duration of each impulse will generally be constant and is referred to, in the following, as the impulse duration. The individual impulses are emitted in succession, in such a manner that the time interval between two successive impulses is always larger than the duration of each individual impulse.
Further, the time interval between the impulses as well as their amplitude should be able to be varied continuously and automatically. Apparatuses by which such electric impulses may be produced are known, but the possibilities of variation offered by these apparatuses are very limited, and the variations are effected by deficient mechanical means.
The present invention has for its object to provide an apparatus by which it is feasible to perform at any time the desired variations in the ranges of variation for the amplitude and time interval of the impulses, and in the manner in which the amplitude and time interval of the impulses are varying.
According to the invention, this result is attained in that the apparatus is fitted with means for producing a rhythmically pulsating current which is utilized for controlling the time interval The apparatus may have two potentiometers through which the rhythmically pulsating current is passing, and from which the controlling voltages are taken that serve to control the time interval and the amplitude of the impulses.
The said rhythmically pulsating currents may be produced in the anode circuit of a discharging valve, by means of a relay the coil of which is inserted in the anode circuit of thevalve, and which alternately charges and discharges a condenser inserted in the control circuit of the valve.
The anode circuit of the valve may contain potentiometers from which the voltages for controlling the time interval and the amplitude of the impulses are taken. In order to be able to reduce arbitrarily to zero the minimum value of the current through the potentiometers, without the relay being prevented from operating, a portion of the circuit containing the relay coil, the valve and the potentiometers may be shunted with a variable resistance.
In order to change the shape of the pulsating current, means may be found for altering the charging current and the discharging current "of the condenser independently of each other.
The impulses may be produced by means of a condenser, by charging or discharging the same by way of a discharging bulb of the kind having between the individual impulses and similarly ably formed by charging and discharging currents for a condenser or, maybe, by an amplification of such currents.
an igniting voltage that is higher than the extinguishing voltage, and by charging or discharging the condenser by way of a discharging valve the grid voltage of which is controlled by the rhythmically pulsating current, the time interval between the impulses being thus altered in accordance with the said current. The minimum time interval between the impulses may be modified by altering a grid bias imposed on the valve. 7
The discharging bulb may preferably be a glow lamp.
The adjustment of the amplitude of the impulses may be effected by an amplifier valve in which the impulses are amplified, and on the grid voltage of which the rhythmically pulsating current is superimposed, in such a manner that the impulse amplitude varies in accordance with the vention,
Fig. 2 the voltage curves for a series of 'impulses produced by means of the apparatus shown in Fig. 1, and
Fig. 3 the voltage curves for two individual impulses.
The apparatus shown in Fig. 1 consists of three parts, viz. one part for producing the rhythmically pulsating current, one part for producing the impulses and for controlling the mutual time interval between the latter, and one portion for controlling the amplitude of the impulses.
The rhythmically pulsating current is .produced by means of a triode valve I the anode 2 of which is connected, by way of a relay coil 3v for a relay 4, to the positive terminal 5 of a source of voltage. The cathode I in the valve I is connected to the negative terminal 6 of the source of voltage by way of two parallel current paths, viz. partly by way of a potentiometer B with a sliding contact 9, and partly by way of a series connection consisting of a resistance I6 and a potentiometer II with a sliding contact I2. The two current'paths may be alike, and are merely shown different in order to indicate that each currentpath may either consist merely of a potentiometer or of a potentiometer connected in series with a fixed resistance. The two potentiometers'may further be replaced by one single potentiometer having two sliding contacts adapted to be adjusted independently of each other. Across a resistance I4 the armature of the relay 4 is connected to the grid I3 of the valve I, which grid is further connected to the cathode I by way of'a resistance I5 and a condenser I6. A battery I'I, the positive and negative terminals of which are marked 18 and I9 respectively, has two cutlets 2i] andZI, the voltage being more positive at the outlet 20 than at the outlet 2|. he'outlet 26 is connected to the cathode I. The positive terminal I6 of the battery is connected, by way of a potentiometer 22 with a sliding contact 23 and, by way of a resistance '24, to the outlet'ZI which by way of a resistance 25 and a potentiometer 26 with a sliding contact 21 is connected to; the negativeterminal I9 of the battery. The sliding contacts 23 and 21 are con.- nected; respectively, to a circuit-breaking contact 28 and a. circuit-closing contact 29 intherelay 4.
When the" current in the relay coil .3 alternately'assumes various values, the armature I3 will alternately'close a contact with the contacts 28" and :29; At the moment-when a contact is closed for instance betweenthe armature I3 and the contact-28, the current in the relay coil will be relatively small. Across the potentiometer 22, the sliding :contact 2.3, the contact 2 8 and the re-' sistance Id-the grid I3 will receive a voltage that is-higher than the voltage imparted subsequently thereto by way of the potentiometer 26, the sliding contact 21 and the contact 29, when the armaturelfi' is attracted. The grid I3, however, does not at once receive the voltage possessed by the sliding contact 23, as the condenser I6 must first be charged by way of the resistances I4 and I 5 which'limit the current. Gradually, as the has dropped to a certain value, th armature I3 recedes, and closes again a contact with the contact 28 causing the condenser I6 to be charged again with a positive voltage on the grid side. By the chargings and dischargings of the condenser I6 produced in this manner, a rhythmically pulsating current is produced in the anode circuit of the valve I, and corresponding voltages will occur on the potentiometers 8 and I I. The form of these voltages may be varied by varying the magnitude of one or more of the coupling elements in the circuit having connection'to the grid I3. When these values have been fixed, the time required by the voltage for rising and for dropping may be varied, independently of each other, by means of the sliding contacts 23 and 2?. If for instance the sliding contact 23 is approached to the Positive end of the potentiometer 22, the voltage difference between the cathode I and the sliding contact 23 will increase. The condenser I5 will consequently be charged more quickly, and the anode current of the valve will increase more quickly.
By the arrangement described heretofore the current through the potentiometers 8 and I I does not vary down to the minimum limit zero. In order to attain this result, there is provided, between the anode 2 and the negative terminal 6 of the source of voltage, a variable resistance 36 serving to shunt the series connection of the valve 1 and the potentiometers 8 and I I inserted in parallel. The resistance 30 is adjusted in such a manner that the current through the valve I and the potentiometers 8 and II will approach zero as closely as desired, when the current in the relay coil 3 has dropped to its minimum value at which the relay armature I3 recedes. The varying current through the relay coil 3 will not be altered in consequence hereof.
Every point of the potentiometer 22 has a voltage that is higher than the voltage required in order that the current passing through the relay coil 3 may be sufficiently intense to cause the coil to attract the armature I3, and every point of the potentiometer 25 has a voltage that is lower than the voltage required in order that the current through the relay coil 3 may be so small that the armature I3 recedes.
The portion of the apparatus in which the impulses controlled by the rhythmically pulsating current are produced, and in which the mutual time interval of the impulses is adjusted, contains a pentode Valve 3| the controlling grid 32 of which is connected, by way of a filter chain consisting of two resistances 3,3 and 34 and a condenser 35, to the sliding contact I2 on the potentiometer II. The valve 3| has further an anode 36, an intercepting grid 31, a shielding grid 38 and a cathode 39. The intercepting gri 31 is connected to the cathode 39. The shielding grid 38 receives a positive voltage by way of a sliding contact 40 on a potentiometer -4I inserted between the terminals 5 and 6 of the source of voltage. A condenser 42 isprovided between the shielding grid 38 and the negative terminal 6. By way of a glow lamp 43, the anode 36 is connected to the positive terminal 5 and, by way of a condenser 44, to the negative terminal 6. The cathode 39 is connected to a slidingcontact 45 on a potentiometer 46 which is inserted in a resistance chain containing further the resistances 41 and 48, and being connected by way of the terminals 5 and :6 of the source of voltage, The cathode 39 is coupled to the negative terminal 6 by means of a condenser 49. I
The'valve 3| acts as a variable resistance disposed as a shunt across the condenser 44. When the condenser is charged by way of th glow lamp 43, the latter is extinguished, and the condenser 44 is discharged by way of the valve 3|, until the voltage over the condenser has become so low that the glow lamp 43 is ignited again, and charges the condenser 44 etc. An impulse is produced at each charging and subsequent discharging of the condenser 44.
The voltage impulses occurring by way of the condenser 44 have a duration that is mainly equal to the time interval between the individual impulses. The voltage rises quickly and in a rectilinear manner to a certain value, and drops then relatively-slowly to a certain lower value, after which it rises quickly again etc. The Voltage curve for the condenser 44 assumes consequently a toothed appearance, each tooth corresponding to one single impulse. The shape of the impulses, however, is. changed during their further passage through the apparatus, as further described in the following.
. The time interval between the impulses may be modified by altering the resistance in the valve 3|. This resistance is depending on the voltage of the grid 32 in comparison with the cathode 39. If the grid voltage rises, the resistance in the valve 3| is reduced and, consequently, the time interval between the impulses becomes'shorter. The grid voltage and, consequently, the time in terval between the impulses are controlled by the voltage of the sliding contact 12 relatively to the cathode 39, and this voltage is determined partly by the rhythmically pulsating current passin through the potentiometer II and partly by the drop of voltage across the resistance that is inserted between the sliding contact 45 and the negative terminal 6 of the source of voltage. This drop of voltage may be regulated by means of the sliding contact 45, the position of which determines the maximum time interval between the impulses. By means of the sliding contact l2, the range of variations for the time interval is adjusted. Gradually as the sliding contact I 2 is approached to the negative end of the potentiometer II, the range of variations for the time. interval becomes smaller and smaller, and finally a constant time interval between the impulses is reached which is determined by the position of the sliding contact 45.
When the maximum time interval for the impulses is altered, the minimum time interval will be altered at the same time. provided that the range of variations remains the same. In order impulses may be reduced, independently of the grid bias for the valve 3|.
The'voltage variations produced on the condenser 44 are directed, by way of a coupling condenser 50, to'the last part of the apparatus in which the amplitude of the impulses is controlled. This part contains an amplifier valve Si in the shape of a pentode with a cathode 52, a controlling grid 53, a shielding grid 54, an intercepting grid 55 and an anode 56. The impulses are directed from the coupling condenser to the controlling grid 53. The anode 56receives a positive voltage by way of a choking coil 51. The intercepting grid is connected to the cathode 52. The shielding grid 54 receives positive voltage by way of a resistance 58, and is coupled to the negative terminal 6 of the source of voltage, by means of a condenser 59. The cathode 52 is connected to the negative terminal '6 by Way ofa variable resistance 60 which is shunted with a condenser 6|. 7 r
The voltage taken from the potentiometer 8 by means of the sliding contact 9 .is directed to the grid 53 by Way of a filter chain consisting of two resistances 62 and 63 and a condenser 64, in such a manner that the constant grid bias determined by the magnitude of the variable resistance 60 is superimposed with the voltage determined by the rhythmically pulsating current passing through the potentiometer,
by way of thelower part of the potentiometer to be able to alter the maximum time interval. Y
without altering the minimum time interval. the range of variations for the time interval must be altered correspondingly. This may be done for instance by inserting, between the sliding contact l2 and the negative terminal of the source of voltage, a variable resistance which s dimen sioned in such a manner, and the controlling sh aft of which is coupled mechanically to the con olling shaft of the potentiometer 46 in such .a manner that a change in the maximum time intervalwill not influence the minimum time nterval, but will solely influence the range of variations. Such a variable resistance is not shown on the drawing. a
The maximum time interval is further dependent on the position of the sliding contact an on the potentiometer 4|. in such a manner that by approaching this contact to the positive end of the potentiometer the time interval between the 8 determined by the positionof the sliding contact 9. The amplification produced in the valve 5| is varied in time with the rhythmically pulsating current. Th amplified impulses aredelivered from a terminal 65 which is connected to the anode 56 by way oia condenser 66, and a terminal 6'! which is connected to the negative terminal 6 of the source of voltage. The range of amplification variations for the impulses may be adjusted by means of the sliding contact 9 on the potentiometer 8, and is varied from zero and upward,'while theminimum amplitude may be adjusted by means of the variable resistance 60. i Y
The magnitude of the impulses directed on to the grid- 53 may be limited by means of a variable resistance 68; one end of which is -connected to the grid 53, and the other end of which is'connected to the negative terminal 6, by way of a condenser 69. When theresistance 68 is reduced, the impulses will be reduced.
As'mentioned above, the shape of each individual impulse is altered during the. passage through theapparatus. The curve of voltage for the voltages "occurring on the condenser 44 has a toothed appearance, each toothcorresponding to one single impulse. When the im-, pulses have passed the condenser 50, which for instance may be about cm., their voltage curve has about the shape of a triangle with a relatively short base, and the duration of the impulses is consequently smaller than the time interval between. two successive impulses. I In consequence of the impedances contained in the o tlet circuit of the valve 5|. the impulses become dipolar; and assume the shape-shown in the voltage on the outlet terminals or the apparatus being plotted as a function of the time. The finely drawn lines H and 12 through the voltage maxima and minima, respectively, of the individual impulses do not indicate the voltages occurring at the outlet terminals of the apparatus, but are merely enveloping curves for the series of impulses, and they illustrate the rhythmically pulsating variation of the impulse amplitude. The portion of the enveloping curves for which the impulse amplitude is increasing and decreasing are called, respectively, the wave rise and the wave drop. By the selection of various amplifier valves, and by a suitable se- 7 lection of the coupling elements contained in the inlet circuit of the valv I, and by the'intro-.
duction of capacities, resistances and self inductions in the grid circuit for the Valve 5|, the shape of the wave rise and the wave drop may be adjusted as desired. Analogously, the modification of the time interval between successive impulses at various points of the enveloping curves may be adjusted as desired. The difference in height between the maxima and minima of the enveloping curves indicates the range of amplitude variation, and the minima of the en- Veloping curves indicate the minimum amplitude. The corresponding time interval between the impulses is the maximum time interval which may be adjusted to any desired value by means of the sliding contact 40, and may be altered inside of any desired range by means of the sliding contact 45. The minimum time interval occurs in the maxima of the enveloping curves, and the difference between the latter and the maximum time interval is the variation range which may be modified by the sliding contact l2, and has the lower limit zero, independently of the maximum time interval.
The time passing between two wave summits of the enveloping curve may be varied by means of the sliding contacts 23 and 21. A change in this range of variations may be effected by altering the magnitudes of the coupling elements entering in the grid circuit for the valve l,or by the addition of further coupling elements. The charging of the condenser l6 may also'be effected by means of one valve more instead of the battery shown, or by means of a mechanically driven sliding contact which alters the voltage of the grid l3.
.Instead of the triode valve I, there maybe used a valve with more grids, any one of which maybe used as a controlling grid. A combinationgrid may also be used having such a num ber of electrodes that/both the productionof the rhythmically pulsating current and the amplitude variation or the variation of the time interval between the individual impulses may be effected in the same valve.
The coupling between the valves 3| and 5! may be altered in such a manner that the impulses are directed from both sides of the glow lamp 43 to cathode 52 and the grid 53, respectively, by means of suitable coupling elements.
,The bulb 43 may be a glow lamp or other known discharging valve, the ignition voltage of which is higher than the extinguishing voltage, for instance a 'so-called gas diode. In order togain stability, the condenser M is coupled to the negative terminal 6 of the source of voltage, but it may also be disposed in parallel to the discharging bulb 43. When a glow lamp is used, the individual impulses occur with the shape shown in Fig.
tus. The figure shows the voltage variation for two successive impulses l3 and 14. The oscillations are dipolar, and the two halves of each impulse variation may be rendered more or less symmetrical by the insertion of impedances in the circuits in which the glow lamp is inserted. The duration and the time interval of the impulses are marked 1? and T, respectively.
The amplifier valve 5| and its coupling may be varied, the impulses, however, being constantly delivered to one of the grids of amplifier valve. The ratios between the shown combinations of fixed resistances and potentiometers should preferably be selected in such a manner that the desired variation will be attained by a full rotation of the controlling shafts of the potentiometers.
The time interval T between the impulses varies mainly between 10 seconds and 450 of a second. The amplitude varies between zero and about 20 volts.
Having thus described my invention, what I claim is: u
1. An apparatus for the treatment of nerves and muscles by means of electric impulses, comprising means for producing a succession of electric impulses, a device for generating a rhythmically pulsating current, means controlled by said pulsating current to vary the time intervals between said individual impulses, and independent ly adjustable means also controlled by said pulsating current to vary the amplitude of said impulses.
2. An apparatus, as claimed in claim 1, in which said device for generating the rhythmically pulsating current includes a condenser which is alternately charged and discharged. i
3. An apparatus, as claimed in claim 1, in which said means forvarying the time intervals between the individual impulses and said means for varying the amplitude of said impulses, each includes a separate potentiometer by way of which the rhythmically pulsating current is passing and from which the controlling voltages for varying the time interval and amplitude, respectively, of the impulses are delivered.
7 4. An apparatus, as claimed in claim 1, in which said device for generating the rhythmically pulsating current includes a discharge valve,v a relay having its coil inserted in thejanojde circuit of the discharge valve, and a condenserv inserted in the inlet circuit of said valve and being controlled by said relay to be alternatelycharged and discharged in order to produce, variations,in the anode current of the valve.
5. An apparatus, as claimed in claim 1, in which said device for generating the rhythmically pulsating current includes a dischargevalve, a relay having its coil inserted in the anode circuit of a said discharge valve, anda condenser inserted 3, at the outlet terminals of the appara- 7 into the] inlet circuit of said discharge .valve and being controlled by said relay to be alternately charged and dischargedin order to produce variations in the anode current of the valve, said means for varying the time intervals between the individual impulses and'said means for varying the amplitude of said impulses, each including 'a separate potentiometer inserted in the anode circuit of said valve, said apparatus including further a variable resistance shunting a portion of said device for generating the rhythmically pulsating current includes a condenser which is alternately charged and discharged and means for altering the charging current and the discharging currents of the condenser, independently of are amplified, means to superimpose the rhythmically pulsating current on the grid voltage of said amplifier valve in order to vary the amplitude of the impulses, and means for altering a grid bias imposed on the valve in order to vary the each other, and consequently the shape of the 6 minimum voltage of the impulses.
rhythmically pulsating current.
7. An apparatus, as claimed in claim ,1, comprising an amplifier valve in which the impulses PREBEN MORLAND. JORGEN ADOLPH SMITH.