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Oct. 15, 1946.
|_. R'o'sA ET'AL.
2,409,317
APPARATUS FOR THE-RECORDING OF SLOW PROCESSES
Filed Feb. 21; 1940
36
INVENTORSI
Laszlo 208a
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areas {
Zak
'
Patented Oct. 15, 1946
2,409,317
vUNETED STATES’ PATENT OFFIQE
2,409,317
APPARATUS FOR THE RECORDING OF
SLOW PROCESSES
Laszlo Rosa, Budapest VIII, and Imre Zakarias,
Budapest VII, Hungary; vested in the Alien
Property Custodian
Application February 21, 1940, Serial No. 320,074
In Hungary February 11, 1939
4 Claims. ' (o1.12s-2.0e)
1
2
So called electro-cardiographs for the pick-up
and recording of the cardiac function are already
known, in which the electric voltage impulses in
duced by the work of the muscles of the heart are
ampli?er tube, should be smaller than 0.03 milli
volt, a tube having a high degree of ampli?ca
tion, corresponding to an ampli?cation factor
g>33 preferably a screen grid tube is employed in
the ?rst ampli?er stage. The voltage to be am
transferred on the luminous screen of a cathode
pli?ed which is admitted to the apparatus through
ray tube or on an electro-mechanical device e. g.
the terminals I—I is impressed through the con
on a galvanometer, and in which the variation as
denser 3 on the control grid 2 of this tube. The
a function of time of the voltages is traced on a
bias voltage of the control grid 2 is supplied by
?lm band kept in uniform motion. In View of the
the battery 5 by means of the resistance 4. The
fact that in electrocardiography the peak values
feeding voltage for the anode 9 and for the screen
of the differences of potential between the elec
grid 8 of the ampli?er tube I is stabilized in the
trodes do not amount to more than to about 2-3
?rst stage by the series resistance l3 and by the
millivolts, an amplifying apparatus comprising a
four-stage stabilizer tube l0, whilst the second
number of stages is required in order to enable
these voltage impulses to operate the recording 15 stage of stabilization is attended to by the sta
bilizer tubes 5 and l’ and by the series resistance
device which possesses a relatively low degree of
it. The stabilizer tubes may be of the well—
sensitivity. In the equipments of known types
known glow discharge type, such as neon tubes,
the necessary supply of heating and anode cur~
which provide substantially‘ a ?xed voltage drop
rent is supplied by batteries forming part of the
equipment. A drawback of this arrangement is 20 thereacross. The four-stage stabilizer tube 10
may comprise four of the tubes shown at 6 and ‘I
that owing to the rapid diminution of voltages
in series so as to break up the voltage drop across
possible in the case of these batteries the ampli
the tubes into stages. An example of a two
?cation is, immediately after putting the appara
stage stabilizer tube device is illustrated at H‘!
tus in circuit, exposed to fluctuations, by which
recording is rendered unreliable, the voltage con 25 in Fig. 4 of British Patent No. 472,951, accepted
October 4, 1937. The current consumption of the
dition of the batteries themselves being in gen
stabilizer tube if! in the ?rst ?ltering stage is
eral unknown to the attendants. Experiments
higher (amounting to about 30-50 milliamperes)
have shown that it is possible to avoid the ?uc
than the current consumption of the stabilizer
tuations of ampli?cation if the voltages required
forfeeding the ampli?er tubes are derived from 30 tubes 6 and l of the second ?ltering stage
(amount to about 5-10 milliamperes), which cir
the electric mains system (if necessary from a
cumstance preferably also ?nds expression in the
motor-car storage battery) and if for stabilizing
dimensions of the tubes in question. ‘The sta
the anode and grid direct voltages of at least the
bilizer tubes 6 and 1 employed in the second ?lter
?rst (input) ampli?er tube at least two mutually
ing stage may possibly be dispensed with, and in
consecutive ?ltering stages having high time con
the remaining ?ltering stages it is possiblev to em
stant are employed, at least one ?ltering stage
ploy voltage stabilizing transformers, circuit ar
consisting of a voltage-stabilizing tube or tubes,
rangements comprising electronic tubes e. g. re
Whilst the remaining ?ltering stages either con
?ex circuit arrangements of stabilizer tubes or
sist of a voltage stabilizing tube or tubes likewise,
or of a voltage-stabilizing transformer, a motor v40 motor generators possessing an adequate amount
of mechanical inertia, the feeding of the last
generator having a sufficient degree of inertia, or
named apparatus being effected by means of the
a circuit arrangement comprising electronic tubes,
e. g. a reflex circuit arrangement of stabilizer
tubes.
alternating or direct current mains system or pos
sibly by means of a motor car storage battery of
>
The diagram of connections of an embodiment 45 6 to 12 volts.
The working point of the screen grid tube l in
shown by way of example of the apparatus ac
the ?rst ampli?er stage should according to the
cording to the invention is represented on the
invention preferably be adjusted in such a man
accompanying drawing.
.
ner that relatively to the anode the fluctuations
_ On the drawing, l denotes the ?rst (input)
ampli?er tube, without the device for heating the 50 of the anode and of the screen grid direct volt
ages should exactly mutually balance. This de
cathode, whilst M denotes the second and I5 the
sired adjustment will be reached if
third ampli?er tube. As, in the case of appara
bia
tus for examining the cardiac function, it is es
sential that the ?uctuations of the feeding volt
AEg2aeg2R¢—-AE‘;—0
ages, expressed for the control grid of the ?rst 55 iniwhich formula AEgz‘ is the ?uctuation of the
2,409,317
4
ampli?er tubes should preferably be taken from
screen grid direct voltage, AEa the ?uctuation of
the anode feeding voltage.
a battery, possibly by means of a voltage divider
of high resistance.
For the calibration of the ampli?er it is pos
sible to derive alternating voltage, preferably by
L11
5602
is the degree of steepness of the anode current
expressed as a function‘ of the screen grid voltage
and Ra the working resistance in the anode cir
cuit, which latter is marked ii on the drawing. f
In order to enable the compensation described 10
above of the voltage ?uctuations to be'achieved,
means of a resistive voltage divider, from the
heating voltage of the ampli?er tubes, it being
possible to impress the said calibrating voltage
on the control grid of the ?rst ampli?er tube.
If in the apparatus, recording is effected by
means of a cathode ray tube, it is preferable to
the anode resistance H is constructed as an ad
employ a cathode ray tube of. such a type the
justable resistance.
fluorescent screen of which emits blue light for
the purposes of taking photographs, and green,
The calculation shows that
in the case of the usual high-frequency pentodes ,
the working resistance has to be adjusted between
50,000 and 100,000 ohms, in order to achieve com
pensation.
,
.
'
In the second ampli?er stage the screen grid
tube 14, and, respectively, in the third ampli?er
stage the triode I5 work with voltages stabilized
in one stage only, the said stabilization being
taken care of by the stabilizer tube i0 and by
the series resistance :13. The anode resistance iii
of the screen grid tube i4 is adjustable likewise,
in the same way as the anode resistance 5 i in the
?rst ampli?er stage in order to enable the work
ing point of the ampli?er tube ill to be adjusted
in such a manner as to ensure that the ?uctua
yellow or white light for the purposes of direct
observation, or in which a secondary luminous
surface is employed. As the inertia of the
human eye amounts to about one-eighth of one
second, the time constant of the luminous sub
stance emitting the green, yellow or white light
should be greater than one-third of one second.
The voltage to be graphically recorded is im
pressed upon one of the pairs of de?ecting plates
of the cathode ray tube, whilst in the case of
25 direct observation a saw-tooth voltage is im
pressed on the other pair of de?ecting plates, the
frequency of which saw-tooth voltage can be
synchronized with that of the heart-‘beat. As
tions of the feeding voltages of the anode and of
the period of one heart-beat may vary between
the screen grid, respectively, should just exact
ly mutually balance. The control grid 49 of the
ampli?er tube iii receives the bias voltage from
about 0.2 and 2 seconds, the saw-tooth voltage
generator should be constructed in such a man
her as to enable the period of oscillation to be
adjusted at least between 0.5 and 2 seconds. The
the battery [3 over the resistance H. The feed
ing voltages for the anode 21 and for the screen
capacity of the condenser, periodically charged
grid 20 of the ampli?er tube M are stabilized
and discharged for producing the saw-tooth
voltage should be assumed at a value higher than
by means of the stabilizer tub-e it and the se
ries resistance I3. The control grid 2% of the
2 micro-farads.
In the case of an electrocardiographic ex
triode l5 receives the bias voltage from the bat
tery 3% over the resistance 30, whilst the control
amination, for instance, the apparatus should
voltage itself is admitted to the control grid 2g 40 be used in the following manner: The electrodes
through the condenser 32. The anode 33 works
?xed to the right and left arms of the person to
on the resistance 34, whilst the ampli?ed voltage
be examined should be connected to the ter
is admitted to the recording device e. g. cathode
minals I—I. The difference of potential pro
ray tube 36 at the terminals O-O by means of
duced by the cardiac function should be am
the condenser 35.
45 pli?ed by means of the tubes I, It, I5; the am
pli?ed voltage should be taken off at the ter
The condensers 22, 23, 2d, 21 and 28 as well as
minals O—O and may be supplied, e. g., to one
the resistance 25 and the switch 26 are employed
pair of deflecting plates of a cathode ray tube,
for in?uencing the width of, i. e. for altering, the
band of frequencies passed by the ampli?er com
from which the variation in time of the differ
posed of the tubes l, I4, l5, and of the elements 50 ence of potential, i. e., the so-called electro
of circuit arrangement belonging to them. It
cardiogram should be photographed on a running
is possible to assure by these means that the am
?lm band.
pli?er should pass those frequencies only, which
What we claim is:
are essential, e. g., in the recording of the cardiac
1. Apparatus for the pick-up and recording of
function, the frequencies of the heart sound: 20 55 slow processes of motion taking place in organs
to 400 Hertz, and the frequencies of the electro- 1 of the human or animal body, especially of the
cardiogram: 0.5 to ‘10 Hertz.
'
function of the heart, the said apparatus consist
Experiments have shown that at least by way
ing of a recording device, of an ampli?er, of a
of ?rst ampli?er tube and of stabilizer tubes it
common power source for the feeding of the am
is necessary to employ tubes of such a kind the 60 pli?er tubes, and of stabilizing means for the
essential electrodes of which are constructed as
anode and grid direct voltages of at least the’
low in microphony as possible and/ or to ?x these
?rst (input) ampli?er tube, said stabilizing means
tubes in a resilient manner. The anode and grid
consisting of at least two consecutive ?ltering
bias voltages of the ampli?er tubes in the second
stages having high time constants, each of the
and further ampli?er stages should be stabilized 65 said ?ltering stages consisting of a voltage stabi
at least in one stage by means of low-frequency
lizing tube device, the current dissipation and
?ltering with the aid of stabilizer tubes, it being
preferably also the dimensions of the voltage
possible to employ, partly or entirely, the same
stabilizing tube device of the ?rst stage being
greater than the current dissipation and dimen
stabilizer tube or tubes for the stabilizing of the
feeding voltages of the various ampli?er stages. 70 sions of the voltage stabilizing tube device of the
second ?ltering stage.
The control grid bias voltage of the ampli?er
2. Apparatus for the pick-up and recording of
tubes can be produced by means of the voltage
slow processes of motion taking place in organs
drop in one cathode resistance, or supplied from;
of the human or animal vbody, especially of the
a stabilized voltage; the bias voltage of the ?rst
ampli?er tube and possibly also those of further 76 function of the heart, the said apparatus con
2,409,317
5
sisting of a recording device, of an ampli?er, of a
common power source for the feeding of the am
pli?er tubes and of at least one ?ltering member
serving for the adjustment in the desired extent
pli?er tubes, in which at least the ?rst ampli?er
of the band of frequencies passed by the ampli
tube is a tube, preferably with screened grid, pos
?er, each ?ltering member being composed of a
sessing a high ampli?cation factor greater than 5 condenser and a resistance, and of stabilizing
33, for the adjustment of the working point
means for the anode and grid direct voltages of
whereof a variable resistance is provided, and of
at- least the ?rst (input) ampli?er tube, said
stabilizing means for the anode and grid direct.
stabilizing means consisting of at least two con
voltages of at least the ?rst (input) ampli?er
secutive ?ltering stages having high time con
tube, said stabilizing means consisting of at least 10 stants, each of the said ?ltering stages consisting
two consecutive ?ltering stages having high time
of a voltage stabilizing tube device, the current
constants, each of the said ?ltering stages con-F)
dissipation and the dimensions of the voltage
sisting of a voltage stabilizing tube device, the"
stabilizing tube device of the ?rst stage being
current dissipation and the dimensions of the
greater than the current dissipation and dimen
voltage stabilizing tube device of the ?rst stage 15 sions of the voltage stabilizing tube device of the
being greater than the current dissipation and
second ?ltering stage.
dimensions of the voltage stabilizing tube device
4. The apparatus of claim 1 including a screen
of the second ?ltering stage.
grid and an anode in said ?rst ampli?er tube, and
3. Apparatus for the pick-up and recording of
a resistance in. series with said anode of the order
slow processes of motion taking place in organs 20 of 50,000 ohms whereby ?uctuations of the anode
of the human or animal body, especially of the
and screen grid voltages substantially neutralize
function of the heart, the said apparatus con—
each other.
,
sisting of a recording device, of an ampli?er, of a
LASZLO ROSA.
common power source for the feeding of the am
IMRE ZAKARIAS.
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