US2133140A - Recording device - Google Patents

Description

Oct. 11, 1938. H. E. HOLLMANN RECORDING DEVICE 5 Sheets-Sheet 1 Filed Jan. 8, 1936 fizz/ ezzzar: Haas Erich Hellman Oct. 11, 1938. 5 HOLLMANN 2,133,140

RECORDING DEVICE Filed Jan. 8, 1956 5 Sheets-Sheet 2 FIG. 2

liwezaibrx ,fians Erik}; Hollm mm Oct. 11, 1938. H. E. HOLLMANN RECORDING DEVICE Filed Jan. 8, 1936 5 Sheets-Sheet 3 A fie/we FIG. 5

HOIZJ Eric/Q Hell/mum y Patented Oct. 11, 1938 UNITED STATES" Application Jam, a, 1936, Serial Na. In Germany December 29, 1934 11 Claima; (01. res-2.06)

The present invention relates to electro-cardlographs and more particularly to an improved system for and method of producing cardiographic records. I

As is well known, electro-cardiographs 'depend for their action on the minute potential variations produced in the human or animal organism by the exciting action of the heart. .By recording these action potentials or currents tapped from different portions of the body such as between the limbs as continuous curves. by means of an electric oscillograph such asan electro-magnetic mirror oscillograph or a cathode ray oscillograph physicians are enabled to draw valuable conclusions on the propagation of the exciting action and other conditions of the heart of a patient.

In measuring and/or recording the voltage in the heart, it is found that the voltage varies according to the direction of theaxis of the heart which latter further changes during a heart beat cycle, so that it has become customary to secure various simultaneous combinations of readings of voltages between different points of the body, such as from, the left arm through the heart to the right arm, hereinafter referred to as action voltage or derivation I; from the left arm to one of the legs such as the left leg, hereinafter referred to as action voltage or derivation II; and from the right arm to the left leg, hereinafter referred to as action voltage or derivation III, or between any other points of the body such as between diiferent points of the patient's breast with theheart' in.the center. By simultaneously recording two or more action voltages upon the same viewing screen and/or record strip and in relation to the same time axis, both the magnitudes and phase differences between the instantaneous potentials of the action voltages during the individual heart beat cycles may be studied and valuable information obtained about the function and anatomical condition of the heart. Q

For the simultaneous recording of two or more action voltages or derivations a corresponding number of recording devices are required. Moreover, the action potential variations obtained are extremely weak, thus making it necessary to use a'separate amplifier to increase the potentials sufficiently so as to effect a deflection of the recording beam such as the light beam in a mirror type oscillograph or the electron beam in a cathode ray oscillograph.

While the improvements of the present invention are primarily useful for cathode ray oscillographic systems they may be employed with equal advantage for any other type of oscillograph, such as a mirror oscillograph. Special advantages are obtained when using a cathode ray oscillograph as a recording devicedu'e to the 5 fact that a cathode ray oscillograph is a potential responsive rather than a current responsive device, whereby. reactions from one tapping circuit or derivation through thebody upon another tapping circuit due to current flow are sub- 10 stantially eliminated.

The method of using a separate amplifier for increasing the action voltages drawn from the patient, apart from the fact of increasing the parts and apparatus required and consequently 15 the initial cost, has the further disadvantage that the amplifiers have to be adjusted to equal gain and matched both as ,to'amplitude and frequency response in order to enable a comparison of both amplitude and phase relation of the in-= 20 dividual cardiographic curves obtained.

It is an object of the present invention to overcome the above difiiculty and to enable the use of a limited number of amplifiers for simultaneously and independently recording a plurality of 25 action voltages drawn from different points of the human body.

With this general object in view the invention in one of its embodiments involves the provision of a system wherein the input of a single ampli- 30 fier is connected periodically and in rapid succession to a plurality of input circuits or connectors applied to the points of the body of a patient from which the action voltages are to be drawn by means of a periodic switching de- 35 vice, while at the same time the output of the amplifienis connected to the respective recording devices synchronously with the connection of the input circuit. In order to preserve the shape of the curves recorded the switching fre- 40 quency is made considerably higher than the maximumfrequency of the heart beat curves or cycles, and furthermore the recording devices are sufiiciently damped to eliminate the eifect of transient potentials produced bythe switching 4:; operation. Since the frequency of the heart beat curves or cycles is rather low, simple mechanical switching means such as oscillating or rotating contact devices may be employed for effecting the synchronous connection of the input and 50 output circuits of the amplifier.

According to another embodiment of the invention especially adapted for simultaneous recording of two action voltages, a single oscillograph is provided with means for alternately 5 shifting its time axis from one position to another in synchronism with the switching of the action voltages to the input of the amplifier.

Accordingly, it is a further object of the invention to provide an electro-cardiographic system for simultaneous and independent recording of at least two action voltages drawn from different points of the human body by means of a single recording device and amplifier.

A further object of the invention is the provision of a system for recording three or more action potentials drawn from the human body with a limited number of amplifiers with or without synchronous switching.

Another object is the provision of a simplified composite cathode ray oscillograph for simultaneously and independently recording a plurality of input potentials hooked up according to a three-pole system upon a single viewing and/or recording screen.

The above and further objects and features of the invention will become more apparent from the following detailed description taken with reference to the accompanying drawings forming part of this specification and wherein Figure 1 illustrates a simple diagram for a multiple electro-cardiograph system employing a single amplifier and synchronous switching devices associated with the input and output circuit of the amplifier,

Figure2 shows a similar system to Figure 1 employing a composite cathode ray oscillograph constructed according to the invention, 1

Figure 3 shows a further modification of the invention for simultaneous and independent recording of several action voltages by means of a single amplifier and oscillograph device,

Figure 4 illustrates a system for simultaneous recording of three action potentials drawn from a human body employing two amplifiers,

Figure 5 illustrates the composite deflecting arrangement for a multiple cathode ray oscillograph embodied in Figure 4, and

Figure 6 shows a system similar to Figure 4 for multiple recording of three action potentials.

Like reference characters identify like parts in the difi'erent views of the drawings.

Referring to Figure 1 of the drawings, there are shown at I, 2 and 3 three tapping points from which action potentials are drawn from the human body by means of suitable connectors strapped to a patient. Thus. point I may correspond to the left arm; point 2 to the right arm; and point 3 to the left leg whereby the voltages obtained between these points are represented by the connecting lines therebetween as shown at I, II and III forming a three-pole voltage triangle. There are further shown at 4 and 5 a pair of oscillogra-phic recording devices for simultaneously recording the action voltages II and III. The recording devices illustrated are of the electro-magnetic mirror type comprising electro-magnets and mirrors I2 and I 3, respectively, suspended on strings passed through the magnetic field in a known manner and upon which light beams from a source 69 are projected to be variably defiected by the oscillations of the mirrors in accordance with the currents applied to the magnet windings. The currents required for energizing the magnets are supplied from a valve amplifier i. In order to record the action voltages II and III simultaneously, the input and output circuits of the amplifier are each connected to the movable members of a pair of synchronously operated switching devices 1 and 8 having cooperating contacts connected to the points I and 2 and to the open ends of the energizing windings of the recording devices 4 and 5, respectively. In the example shown for recording the two action voltages II and III, the tapping point 3 and the inner serially connected ends of the energizing windings of the recording devices 4 and 5 are grounded. The switching devices I- and 8 may be operated in any suitable manner such as by means of electromagnets energized by interrupted direct current impulses or the like produced in the example shown by an electro-magnetic vibrator or buzzer 9.

In an arrangement of this type, it is seen that the voltage II between the tapping point I and ground isapplied to the input of the amplifier in the position III of the switch I while in the position II of the switch the action voltage III between the point 2 and ground is impressed upon the amplifier. Simultaneously the corresponding oscillograph devices 4 and 5 are connected to the output of the amplifier in synchronism with the switch 8 and as a result both oscillograph devices receive short current impulses the intensity of which is proportional to the instantaneous potentials prevailing at the tapping points I and 2. The mirrors I2 and I3 are therefore deflected in proportion to the instantaneous variations of the action voltages H and III and may serve to produce oscillographic records on a recording strip such as a photographic film or paper in a known manner. In order to prevent interference by the transient switching potentials, the oscillograph devices should be sufiiciently damped. Further details, such as the circuit connections, provision of supply voltages, etc., for the amplifier 6 and the rest of the apparatus have been omitted from the drawings for the sake of simplicity of illustration and disclosure and as not forming a part of the present invention.

The principle of the invention as illustrated by Figure 1 may be extended to the recording of all three action potentials. For this purpose, it is advantageous to consider the three tapping points I, 2 and 3 as the potential points of a three phase system subject to the general law of such systems according to which the geometrical vector sum of the three voltages at every instant is equal to zero; or in other words, the sum of the voltages between I and 3 and 2 and 3 must at any time be equal to the voltage between I and 2. Thus by forming the differential voltage between the action voltages II and III the action voltage I may be obtained.

In place of electro-magnetic recording devices as illustrated, it is understood that any other oscillograph device may be used such as a cathode ray or glow discharge oscillograph without departing from the spirit of the invention.

If a cathode ray oscillograph is used, the arrangement may be greatly simplified by using a composite multi-beam oscillograph device constructed according to the invention in place of three separate oscillograph tubes. In a device of this character only four electrostatic deflecting plates are required for effecting the deflection of the three electron beams as illustrated in greater detail in Figure 2. In the latter there is shown a system for simultaneously recording three action voltages between points I, 2 and 3 related to each other according to a delta system by means of a single amplifier and a single composite multi-beam cathode ray oscillograph. The input circuit for the amplifier is substantially similar to that shown in Figure 1. The contacts 'ot :the;.s witching device fijiasso with. the output circuit or the. ampiiiierare con-.

1 concentrated.electron beam tr, pencil; The deflecting fieldfor the'centraliel'ectron beam is producedbetw'een' the-plates. and If! while the; de-

1 I ilecting:fleldsffor the outer electron beams are :produced between. the plates i6 and I9 and, the I plates i1 and-, respectively; Depending on 1 the position of the switches land 8, plates liand I I are charged to a potential proportional to" the ,instantaneouspotentials at the tapping p ints I I and}, respectively. [Inorder to prevent a dis sipation of these charges vduringthe Switching I eriods by leakage and'to imposesuflicient dampof vacuum or gaseous discharge tubes operating ing upon the deflecting systems; the plates liiand i! have connected; therewith suitable damping elements such as resistances 2| and condensers ,22 placed betweenthe plates and ground. It is seen that in this manner an instantaneous .voltage corresponding to the action voltage II is impressed upon the plates iGjand l9, and a further voltage corresponding to the action voltage III :is impressed upon the plates 'l'I and 20, while a voltage proportional to the difierence between the action voltages II and III corresponding to the action voltage I is set up between the plates l6 and l Tin such a manner that the three action voltages are simultaneouslyrecorded by the three electron beams. The arrangement of the remaining parts of the cathode ray tube I8 such as the luminescent screen-impinged by the electron beams to produce luminous recording spots and further means for producing a permanent record on a photographic strip are obvious to those skilled in the art and have been-omitted from the drawings and disclosure for simplification. I In an analogousfmanner the action voltage I may be obtained by the difference between the currents supplied by the amplifier. if a current responsive recording device is used. In the latter case, however, reactions and disturbances may occur under certain circumstances with re-'- gard to the distribution or the current for wh ch reason an, electrostatically responsive recording device such as-a cathode ray oscillograph is to be preferred in practice.

In place of electro-magnetically operated synchronous switching devices any equivalent known arrangement may be used such as rotating contact devices mounted upon the same shaft,.or electronic switching may be employed by means substantially without inertia and controlled by suitable alternating control potentials. It is further understood that the invention may be employed for'recording' more than three action voltages by means of a common amplifier by correspondinglyincreasing the number of switching contacts, as is readily understood.

Referring to Figure 3, there is shown an arfrangement for simultaneously recording tw-o action voltages '(Iand H) though a single amplifier and by means of'a single recording device by alternately displacing the zero axis of the recording device synchronously withv the connection faiaa i'o' elated or heinput' circuit 0'! the amplifier. In the example illustrated the action voltage I is connected to the in-put of the amplifier 26 in the position 23 ofa'vibrating switch 24 while the action voltage II is connected to the amplifier input in ,the'opposite position-25 or the. switch.

There. is further shown a means-such as a battery 21 for impressing an additional di'fierentiating potential inseries with the action voltage II to effect 'a displacement of the zero or time axis on. themoving recording strip 29 of the record'- ing device 28connected to the output circuit of the amplifier 26; Thus,-in the position 25 of the switch 24, the small additional voltage supplied by the battery 21 is also amplified in such'a mannerfl-that the recording beam of the indicating device is displaced by a definite distance shownat 30. In this manner the two action potentials are 'diiferentiat'ed from each other by displacementoi the zero or time axis by an amount equal to the deflection 30 on the recording strip 28. If

now the action voltages are superimposed aiternately and in rapid succession by the action of the vibrating switch 24 and at a frequency which is high relative to the frequency of the heart beat cycles or curves to be recorded, cardiographic curves representing the variations of the .action potentials l and 2 are recordedabove-the respective zero or-time axes on the recording strip. 1 i

This simplemethod offers theadvantage over previous arrangements that only a single oscillographic device isrquired which does not require any smoothing or damping elements due to the fact that the oscillograph is operating continuously during both switching! periods in such a manner that the recording is independent of transient potentials between the switch-v ing periods, since'only the instantaneous values are recorded without integrationas in the case of the previously described arrangement. III" the switching is instantaneous as is true of most mechanical switches, the luminous recording spot will change so quickly to and from the two axes that the change will hardly be noticeable or only a slight shadow 'be produced between the two cardiographic records.

While it is possible by an arrangement of this type to record only two action; voltages, the

system has great advantages due to its simplicity and etliciency where not more than two simultarieous records are required.

' In certain cases the switching may cause annoyance to sensible patients although weak capacitative charging currents may be impressed upon the patient'withou't harm if the apparatus is suitably designed and constructed.

Inview of the distortions which may occur in an electro-cardiogram due to the slightest irritation of the patient, it may be desirable incertain cases to eliminate entirely any potential variations in the patient circuit and to effect a displacement of thezero axis of the recording device in another portion of the system. For this purpose a second contact may be provided upon the movable member of the switch 24 by means of which either the bias of an intermediate stage, the plate voltage or the magnitude of the output load resistance of the amplifier 26 may be varied synchronously with the switching operation. Furthermore, the synchronous displacement of the zero axis may be efl'ected independently of the recording device such as by directing the light beam of the oscillograph to an 1 auxiliary oscillating mirror mounted upon the tongue or movable member of the switch 24 in such a manner as to project the light beam to one zero axis in one position of the switch and to the other zero axis in the other switch position. Finally, if a cathode ray oscillograph is employed the zero point may be displaced magnetically by means of a small magnetic field coil with an energizing circuit connected and disconnected by an additional contact associated with the switch 24 to deflect the cathode ray periodically to and from the two time axes.

Referring to Figure 4 there is shown a system for recording three action voltages such as supplied from a triangular tapping system previously described whereby only two amplifiers without switching are required. The action voltages I and II are applied to a triple-cathode ray oscillograph 32 through the intermediate amplifiers 30 and 3|. The electron beams for the tube 32 are produced by means of cathods 33, 34 and 35 surrounded by concentration cylinders 50, 5| and 52, respectively, or any other electron-optical concentrating systems. The cathodes are further arranged opposite the openings 36, 3'! and 38 of a common diaphragmatic anode or focussing electrode 53. In place of three separate deflecting systems for the electron beams, a composite deflecting arrangement comprising four electrostatic deflecting plates 39, 40, 4| and 42 arranged in parallel is provided similar to that shown in Figure 2. The electron beam produced by the cathode 33 is passed between the deflecting plates 39 and 40; the electronbeam produced by the cathode 34 is passed between the deflecting plates 49 and 4|; and the electron beam produced by the cathode 35 is passed between the deflecting plates 4| and 42.

The operation of an arrangement of this type will be better understood by disregarding the amplifiers 30 and 3|. In the latter case the voltage triangle I, 2 and 3 is connected to the four deflecting plates 39 to 42 in such a manner that point 3 is connected to the two outer plates 39 and 42 which accordingly are at the same potential while the points and 2 are connected to the two central plates 40 and 4|, respectively. As is seen, the voltage I is impressed upon the plates 39 and 40 and the voltage II is impressed upon the plates 4| and 42 while the voltage III appears between the plates 40 and 4|. As a result, the three electron beams are deflected by the three voltages and three simultaneous cardiographic records produced upon the luminescent screen applied to the opposite end of the tube. In order to obtain a time axis for the curves obtained, either a moving recording strip or rotating mirror may be provided or the electron beams may be simultaneously deflected linearly in a direction at right angles to the deflection effected by the plates," and 42. For the latter purpose according tg a further feature of the invention a common/pair of time sweep deflecting plates 43 and 44 (see Figure 5) extending over all four deflecting members 39 to 42 are provided connected to a suitable source of sweep potential preferably of saw tooth shape' anodes of the amplifiers 45 and 46 provided with load impedances 41 and 48 connected in series with the anodes and a common anode potential source 49. If both amplifiers are of equal design and balanced to have equal gain only the voltage III will appear between the anodes whereby the central electron beam is deflected in accordance with the variations of this voltage. The effect of the direct current voltage drops produced by the impedances 41 and 48 are eliminated or balanced by connecting the outer plates 39' and 42 to suitable tap points of the anode potential source to prevent initial displacement of the outer electron beams from their zero positions. Otherwise, the arrangement and operation according to Figure 6 is substantially similar to that described in connection with Figure 4.

The arrangements and methods disclosed by the invention are not limited to the recording action potentials drawn from a human body but as is understood equally apply to the amplification and/0r recording of any potential variations related in accordance with a three-pole system.

It will be evident from the above that the invention is not limited to the specific arrangements and methods shown and disclosed herein for illustration, but that the underlying inventive concept and novel principle is susceptible of numerous variations and modifications coming within the broader scope and spirit of the invention as defined in the appended claims.

I claim:

1. In an electro-cardiograph for simultaneously recording a plurality of action voltages drawn from different contact points of a patient, a' recording system, a common amplifier, switching means for successively and periodically connecting the input of said amplifier to the different contact points at a frequency substantially higher than the highest frequency of the action voltages to be recorded, means operating in synchronism with said first means for separately recording the individual action voltages as curves upon diilerent zero axes of the recording system, and damping means for said recording system to eliminate the effect of transient switching potentials upon the curves recorded.

2. In a device for simultaneously recording three action voltages of a human organism linked up with each other in the form of a three-pole system, a common amplifier, means for periodically connecting the input of said amplifier in rapid alternation to two of said voltages at a rate which is high relative to the variations of said action voltages, and means for recording the third of said voltages as a differential voltage of the two amplified voltages.

3. In an electro-cardiograph, means for simultaneously recording a plurality of action potentials drawn from different contact points of a patient, comprising a plurality of recording units each coordinated to one contact point for individually recording the action potentials tapped therefrom, a common'amplifier, switching means for periodically connecting the input of said amplifier in rapid succession to the separate contact points, further switching means for successively and periodically connecting the output of said amplifier to the respective recording units in synchronism with said first switching means, the frequency of said switching means being high compared with the frequency of the action voltages to be recorded, and damping means for said recording units to eliminate the eiiect of tran- 4. In apparatus for simultaneously recording a three alternating voltages linked up with each other in the form of a three-pole system, a cathode ray tube comprising means for producing three separate cathode rays and four defleeting members arranged side by side, each of said cathode rays passing between two of said deflecting members, the two 7 outer deflecting members being connected to one pole of said system and each of the two inner deflecting members being connected to one of the remaining two poles of said voltage triangle, whereby each of said rays is controlled by one of said voltages. v

5.,Inv apparatus for simultaneously recording three alternating voltages ,linked up with each other in the form of a three-hole system, a cathode ray device comprising means for pro- .ducing three separate cathode rays, a first deflecting arrangement comprising four electrostatic deflecting plates arranged side by side, each of said cathode rays passing between two plates of said deflecting arrangement, a second deflecting arrangement comprising a pair of deflecting plates perpendicular to and coextensive with said first deflecting arrangement, and means for impressing the potential at one pole of said system upon both of the outer plates of said first deflecting arrangement and for impressing each of, the potentials at the remaining poles of said system upon one of the inner plates of said first deflecting arrangement, whereby all three cathode rays are individually deflected by said first deflecting arrangement in one plane by the voltages of said system and may be simultaneously deflected by a voltage impressed upon said second deflecting arrangement in a perpendicular plane.

6. Means for simultaneously recording three alternating voltages linked up with each other according to a delta circuit comprising a composite cathode ray oscillograph, means for producing three separate electron beams therein and an electrostatic deflecting system comprising four deflecting plates arranged substantially parallel to each other, each of said cathode rays passing between two of said deflecting plates, and connections from both outer deflecting plates to one pole and from each of the inner plates to one of the remaining poles of said deltas circuit.

'7. Means for simultaneously recording three alternating voltages linked up with each other in a delta circuit comprising a composite cathode ray oscillograph, means for producing three initially concentrated substantially parallel electron beams therein, a common diaphragmatic focussing electrode having three apertures each passing one of said electron beams, and an electrostatic deflecting system comprising four deflecting plates arranged substantially parallel to each other, each of said electron beams passing between two or said deflecting plates, and connections from both outer deflecting plates to one pole and from each of the inner plates to one of the remaining poles of said delta circuit.

8. In a device for the simultaneous indication of three alternating voltages linked up with each other in the form of a three pole system, one of said poles being earthed, the combination of two amplifiers the input circuit of each of which is connected to one of the two free poles of said three-pole system and a common cathode ray oscillographic device comprising means for producing three cathode rays, four deflecting plates in linear arrangement, each one of said three rays being flanked by two of said deflecting plates,

the two outer ones of said deflecting plates being earthed and the two inner ones of said deflecting plates each being connected to one of said two amplifiers, respectively.

9. In a device for the simultaneous recording of three alternating voltages linked up with each other in form of a three pole system, one pole of which is earthed, of a common amplifier, a com mon cathode ray oscillographic tube, means for producing three separate cathode rays therein, four deflecting plates in said tube in linear arrangement, the two outer ones of said deflecting plates being earthed, means for alternately connecting the two inner ones of said deflecting plates to the input circuit of said common amplifier in rapid periodicity and means for synchronously connecting said amplifier to each of said two free poles of the said three pole system.

10. In a device for the recording of more than one action voltage of a human organism, a com--v mon amplifier, recording devices respectively adapted for recording each of the action voltages, means for periodically connecting the output of said amplifier in rapid succession to each of the said respective recording devices, and electric damping means adapted to suppress the recording of the switching impulses to permit the simultaneous recording of said alternating voltages.

11. In a device for simultaneously recording three action voltages of a human organism linked upwith each other in the form of a three-phase system, a cathode ray tube comprising means including a common anode for producing three separate cathode rays, four deflecting members for said three rays arranged parallel to each other and at equal distance from said anode, the two outer deflecting members being connected to one pole of said three-phase system, and means including a common amplifier for periodically connecting each of the remaining poles of said system to one of the inner deflecting members through said amplifier in rapid succession.

HANS ERICH HOILMANN.

CERTIFICATE OF CORRECTION.

Patent No. 2,1 ,1uo. October 11, 19

HANS ERICH HOLIMANN.

It is hereby certified that the above numbered patent was erroneously issued to the patentee, said "Hollmann" whereas said patent should have been issued to Radio Patents Corporation, a corporation of New York, as assignee, as shown by the record of assignments in this office; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 15th day of November, A. D. 19

enry Van Arsdale (Seal) 7 Acting Commissioner of Patents.

Images