U.S. patent number 3,810,457 [Application Number 05/301,675] was granted by the patent office on 1974-05-14 for diagnostic apparatus for automatically generating an intensity-time diagram showing points of minimum involuntary muscle movement.
This patent grant is currently assigned to Robert Bosch Elektronik GmbH. Invention is credited to Lutz Bottcher, Karl-August Heyne.
United States Patent |
3,810,457 |
Bottcher , et al. |
May 14, 1974 |
DIAGNOSTIC APPARATUS FOR AUTOMATICALLY GENERATING AN INTENSITY-TIME
DIAGRAM SHOWING POINTS OF MINIMUM INVOLUNTARY MUSCLE MOVEMENT
Abstract
Both amplitude and pulse width of pulses applied to the muscle
are varied automatically, a given number of pulses being applied at
a given amplitude and pulse width prior to increasing the
amplitude. The given number varies with the pulse width. The
amplitude is increased until involuntary muscle movement results.
The same procedure is repeated at the subsequent pulse width.
Inventors: |
Bottcher; Lutz (Berlin,
DT), Heyne; Karl-August (Berlin, DT) |
Assignee: |
Robert Bosch Elektronik GmbH
(Berlin, DT)
|
Family
ID: |
5825938 |
Appl.
No.: |
05/301,675 |
Filed: |
October 27, 1972 |
Foreign Application Priority Data
|
|
|
|
|
Nov 24, 1971 [DT] |
|
|
2158132 |
|
Current U.S.
Class: |
600/554 |
Current CPC
Class: |
A61B
5/4519 (20130101); A61B 5/1106 (20130101) |
Current International
Class: |
A61B
5/11 (20060101); A61N 1/08 (20060101); A61b
005/05 () |
Field of
Search: |
;128/2.1R,419P,419R,421,422,423 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Kamm; William E.
Attorney, Agent or Firm: Striker; Michael S.
Claims
What is claimed as new and desired to be protected by Letters
Patent is set forth in the appended claims:
1. Diagnostic apparatus for generating points of minimum
involuntary muscle movement as a function of amplitude and duration
of electrical pulses applied to said muscle for entry of an
intensity-time diagram, comprising, in combination, adjustable
pulse generator means for furnishing a sequence of pulses, each of
said pulses having an amplitude and a pulse width; electrode means
connected to said adjustable pulse generator means and adapted to
be placed in operative proximity of said muscle for applying said
pulses thereto; control means connected to said adjustable pulse
generator means for controlling said pulse width to one of a number
of selectable pulse widths; first counting means connected to said
pulse generator means, for counting said pulses and automatically
changing said amplitude of said pulses following receipt of a given
number of said pulses; varying means connected to said first
counting means, for varying said given number in dependence upon
said pulse width of said pulses; and stop means for stopping said
first counting means upon appearance of said involuntary muscle
movement, said amplitude and said pulse width of said pulses of
said adjustable pulse generator means at appearance of said
involuntary muscle movement constituting the coordinates of one of
said points of minimum involuntary muscle movement.
2. Apparatus as set forth in claim 1, wherein said stop means
comprise manually activated switch means for activation by the
operator of said apparatus upon observance of said involuntary
muscle movement.
3. An arrangement as set forth in claim 1, wherein said stop means
comprise sensor means for sensing said involuntary muscle movement
and furnishing a corresponding stop signal.
4. Apparatus as set forth in claim 1, wherein said adjustable pulse
generator means comprise a source of current, output switch means
for connecting said source of current to said electrode means when
activated, and control pulse generator means for furnishing control
pulses for activating said output switch means.
5. Apparatus as set forth in claim 4, wherein said output switch
means comprise semi-conductor switch means.
6. Apparatus as set forth in claim 4, wherein said control pulse
generator means comprise first timing means for determining the
pulse width of said control pulses; and wherein said control means
comprise additional timing means, and timing switch means for
connecting said additional timing means to said control pulse
generator means for varying the pulse width thereof.
7. Apparatus as set forth in claim 6, wherein said timing switch
means comprise timing counter means.
8. Apparatus as set forth in claim 7, wherein said first counting
means comprise amplitude control counting means furnishing counting
output signals each signifying a predetermined multiple of said
given number of electrical pulses, and amplitude control circuit
means connected between said amplitude control counting means and
said source of current, for varying the amplitude of said
electrical pulses in dependence upon said counting output
signals.
9. Apparatus as set forth in claim 8, wherein said first counting
means further comprise control pulse counting means connected to
said control pulse generator means, for counting said control
pulses and furnishing a counter advance signal advancing the count
on said amplitude control counting means when the number of
so-counted control pulses is equal to said given number.
10. Apparatus as set forth in claim 9, further comprising first
connecting means connected between said timing counter means and
said amplitude control counting means for varying said given number
in dependence upon the output of said timing counter means.
11. Apparatus as set forth in claim 10, further comprising means
resetting said control pulse counting means in response to said
counter advance signal.
12. Apparatus as set forth in claim 11, further comprising reset
means connected to said amplitude control counting means for
resetting said amplitude control counting means a predetermined
number of counts in response to each activation of said reset
means.
13. Apparatus as set forth in claim 12, wherein said amplitude
control counting means has a reverse counting input; and wherein
said reset means comprise second pulse generator means for
furnishing a sequence of reset pulses upon activation, reset pulse
counting means for counting said reset pulses and for furnishing
corresponding reset counting output signals, and means for applying
said reset pulses to said reverse counting input of said amplitude
control counting means and for blocking the application of said
reset pulses to said reverse counting input in response to a
predetermined one of said reset counting output signals.
14. Apparatus as set forth in claim 13, wherein said means for
applying and blocking said reset pulses from said reverse input
comprise AND-gate means.
15. Apparatus as set forth in claim 14, wherein said reset pulse
counting means furnish said predetermined one of said reset
counting output signals at a predetermined reset counting output
terminal; wherein said timing counter means has a forward counting
input; further comprising inverter means connecting said
predetermined reset counting output terminal and said forward
counting terminal of said timing counter means.
16. Apparatus as set forth in claim 15, further comprising
additional inverter means connected to the output of said AND-gate
means; and additional AND-gate means having a first input connected
to the output of said additional inverter means, a second input
connected to the output of said control pulse generator means, and
an output connected to the input of said control pulse counting
means, whereby said predetermined reset couting output signal
causes said additional AND-gate means to become conductive and
permit the application of said control pulses to the input of said
control pulse counting means.
17. Apparatus as set forth in claim 16, wherein said stop means
furnish a stop signal for terminating the operation of said second
pulse generator means and for resetting said reset pulse counting
means and said control pulse counting means.
18. An arrangement as set forth in claim 17, wherein said stop
means comprise manually activatable switch means.
19. An arrangement as set forth in claim 17, wherein said stop
means comprise electromechanical transducer means.
20. Apparatus as set forth in claim 19, wherein said
electromechanical transducer means comprise capacitor winding means
applied in operative vicinity of said muscle, circuit means
connected to said capacitance pickup means to furnish an electrical
signal in response to capacitance changes resulting from said
involuntary movement of said muscle, filter means for filtering
said electrical signal, and threshold means connected to the output
of said filter means.
21. Apparatus as set forth in claim 20, further comprising start
signal furnishing means; bistable circuit means connected to said
start signal furnishing means and having a "0" output connected to
said timing counter means for setting said timing counter means to
a determined count and a "1" output; NAND-gate means having a first
input connected to said "1" output of said bistable circuit means,
a second input connected to said predetermined reset counting
output terminal and an output connected to said control pulse
counting means; and additional control pulse counting means for
counting said control pulses and for advancing said timing counter
means in response to a predetermined number of so-counted control
pulses, said predetermined number varying as a function of the
count on said timing counter means, said additional control pulse
counter means having reset means for resetting said additional
control pulse counting means upon receipt of said predetermined
number of control pulses.
22. Apparatus as set forth in claim 23, wherein said stop means
furnish a stop signal resetting said bistable means to furnish said
"0" output.
23. Apparatus as set forth in claim 22, further comprising means
interconnecting said stop means and said additional control pulse
counting means for causing said stop signal reset said additional
control pulse counting means.
24. Apparatus as set forth in claim 1, further comprising means for
indicating said points on said intensity-time diagram, said means
comprising a plurality of lamp means each connected to a
corresponding output of said amplitude control counting means, lamp
back means for supporting said lamps, each in a predetermined
position relative to the other of said lamps, recording means for
having said intensity-time diagram inscribed thereon positioned to
receive light from said lamp means, table means for supporting said
recording means, and moving means for moving said table means in a
direction perpendicular to said lamp bank means, to a position
corresponding to the output of said timing counter means.
25. Apparatus as set forth in claim 24, further comprising fine
positioning means for furnishing an exact adjustment of the
position of said recording means relative to said lamp bank
means.
26. Apparatus as set forth in claim 25, wherein said moving means
comprise motor means; wherein said table means has a plurality of
markings in the direction perpendicular to the axis of said lamp
bank means; and wherein said fine positioning means comprise sensor
means for sensing said markings and furnishing a marking signal in
response thereto, and connecting means connecting said sensor means
to said motor means for stopping said motor means in response to
said marking signal.
27. Apparatus as set forth in claim 26, wherein said sensor means
comprise photoelectric sensor means.
Description
BACKGROUND OF THE INVENTION:
This invention relates to a diagnostic apparatus for generating an
intensity-time diagram showing points of minimum involuntary muscle
movement as a function of amplitude and duration of electrical
pulses applied to said muscle.
It is known that when electrical pulses are applied to the muscles
in a human body, and in particular when these pulses are current
pulses, then a healthy muscle will respond to pulses having
amplitudes larger than a given amplitude at a given pulse width by
contracting. However, muscles injured by sickness contract at
different values from those causing contraction in healthy muscles.
Thus in order to diagnose illnesses certain intensity-time diagrams
are recorded showing characteristic values at which the muscles
contract. These diagrams give a good indication of the condition of
the muscles. It should be noted that for this discussion the term
intensity will be taken to mean the amplitude of the pulse applied
to the muscle, while the term time will refer to the pulse width of
the pulse applied to the muscle.
Diagnostic apparatus of the above-described type is known wherein
the adjustment of the pulse width takes place automatically while
the amplitude of the pulses is set by hand. The point at which the
muscle contraction occurs is then recorded by means of a two
coordinate type recorder which is activated by means of a
switch.
SUMMARY OF THE INVENTION
It is the object of the present invention to furnish diagnostic
apparatus for generating an intensity-time diagram showing points
of minimum involuntary muscle movement as a function of amplitude
and duration of electrical pulses applied to said muscle, wherein
the required amplitude adjustment as well as the duration
adjustments are carried out automatically.
It is a further object of the present invention that apparatus of
this type be combined with recording apparatus which is both
accurate and simple.
It is a further object of the present invention to greatly decrease
the time required to generate the above-mentioned intensity-time
diagram.
The present invention comprises adjustable pulse generator means
furnishing a sequence of electrical pulses, each of said pulses
having a determined amplitude and pulse width. It further comprises
first counter means connected to said pulse generator means for
counting said electrical pulses and automatically changing the
amplitude of said pulses following receipt of a given number of
said pulses. Varying means vary said given number in dependence
upon said pulse width of said pulses. Finally, stop means stop said
first counting means upon appearance of said involuntary muscle
movement.
The novel features which are considered as characteristic for the
invention are set forth in particular in the appended claims. The
invention itself, however, both as to its construction and its
method of operation, together with additional objects and
advantages thereof, will be best understood from the following
description of specific embodiments when read in connection with
the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWING:
FIG. 1 shows an intensity-time diagram;
FIG. 2 is a block diagram of the apparatus of the present invention
required for determining the rheobase;
FIG. 3 is a block diagram of the portion of the apparatus required
for determining the chronaxie;
FIG. 4 is a circuit diagram showing the control pulse
generator;
FIG. 5 is a circuit diagram showing the amplitude control control
means;
FIG. 6 is a circuit diagram showing the circuit means for changing
the pulse width and pulse interval of the pulses furnished by the
generator of FIG. 4;
FIG. 7 is a schematic diagram of the sensor means for sensing the
muscle contractions;
FIG. 8 is a circuit diagram showing the recording arrangement;
and
FIG. 9 shows the interconnection between counters 12, 16 and 17 of
FIG. 2.
DESCRIPTION OF THE PREFERRED EMBODIMENTS:
A preferred embodiment of the present invention will now be
described with reference to the drawing.
FIG. 1 shows an intensity-time diagram as is to be generated by the
present invention. The pulse width of the applied pulses is plotted
along the abscissa, while the ordinate represents the amplitude of
the pulses in milliamps. Associated with each of the pulse widths
shown along the abscissa is a determined pulse interval. Thus for
pulses having a pulse width of one second, the interval between
pulses is two seconds and, therefore, the width/interval ratio 0.5.
For a pulse width of one second and an interval of 2 seconds, the
current intensity is measured which is just barely sufficient to
effect a minimum involuntary muscle movement, that is a contraction
or twitching. The so-found valve is designated as the basic
threshold or rheobase. It is designated by the letter A in FIG. 1.
A second important point in the diagram is designated with
reference letter B, which represents the chronaxie. For determining
the chronaxie, the time interval is measured for which a current
having twice the amplitude of the rheobase value must flow in order
that the minimum involuntary muscle movement takes place (the time
interval herein referred to is the pulse width of the applied
pulses). A further value, designated by E in FIG. 1 is designated
as use time and represents the pulse width required to cause a
minimum involuntary muscle movement when the pulse amplitude is the
same as that of the rheobase.
The points mentioned above, as well as the curves connecting said
points, can of course be derived from pulses having different pulse
shapes. The curve designated by C was derived using rectangular
pulses, while the curve having reference numeral D indicates a
curve derived using pulses having a logarithmic shape. These curves
and the rheobase and chronaxie values can be used to drawn
conclusions about the condition of the muscles of the patient.
In FIG. 2, an electrode 10 is connected to the patient in order
that the diagram described in FIG. 1 may be generated. The
electrode 10 is connected to a current source 11 which has
associated amplitude control circuit means. The current source 11
and the amplitude control circuit means associated therewith are
connected to the outputs y.sub.1 -y.sub.n of amplitude control
counting means denoted by reference numeral 12. The amplitude of
the current applied to the patient varies as a function of the
count registered on the amplitude control counting means, that is
on which the outputs y.sub.1 -y.sub.n is energized. Lamps 13 are
connected, one to each output y.sub.1 -y.sub.n. These lamps thus
indicate the count on counter 12 and thus the amplitude of the
pulses applied to the patient. Each lamp lights when the output to
which it is connected caries a "1" signal. The lamps 13 are also
shown again as part of the means indicating the point in the
intensity-time diagram, 28. They are mounted in a lamp bank 32.
The reverse counting input (R) of counter 12 is connected to the
output of AND-gate means 14. The forward counting input (F) of
counter 12 is connected to the output of control pulse counting
means 17 whose input is connected to control pulse generator means
18 through additional AND-gate means 15. The second input of
additional AND-gate means 15 is connected via an inverter 19 to the
output of AND-gate 14, whereby control pulses generated by pulse
generator 18 are transmitted to the counter 17 when the output
signal of AND-gate 14 is a O signal. Under these conditions counter
17 counts the pulses generated by pulse generator 18. When the
number of so-counted control pulses is equal to a given number,
counter 17 furnishes a counter advance signal to amplitude control
counting means 12, thereby advancing the count on counter 12 by one
unit. This increases the amplitude of the pulses furnished by stage
11 to electrode 10. Further, it causes the next-following lamp 13
to light. The count of counter 17 at which the counter advance
signal is furnished in turn depends upon the output of counter 16
herein referred to as timing counter means.
The control pulses furnished by the pulse generator 18 are also
applied directly to stage 11. In this stage they operate switching
means which cause the current pulses to be applied to electrode 10
with a frequency and a pulse width determined by the pulses
furnished by pulse generator 18. The pulse width and the frequency
of the pulses furnished by pulse generator 18 in turn depend upon
the output of the timing counter means, namely counter 16.
The reset pulse counting means, namely a counter 20 have an input
connected to the output of AND-gate 14. A predetermined reset
counting output terminal is connected to one input of AND-gate 14,
which causes AND-gate 14 to become conductive when counter 20 has
reached a particular count. Further, the forward counting input of
counter 16 is connected to the predetermined reset counting output
terminal of counter 20 (designated 3 0 in FIG. 2) through an
inverter 21. Thus as soon as a zero signal appears at the selected
output of counter 20, counter 16 is advanced by one count. The
second input of AND-gate 14 is connected to the output of second
pulse generator means 22. Second pulse generator means 22 have an
input connected to a switch 23, closing of which furnishes a reset
signal starting said second pulse generator means. Power is
supplied to the arrangement shown in FIG. 2 through a main switch
which is not shown.
The first input of AND-gate 14 is also directly connected to the
first input of a NAND-gate 24 to whose second input is applied one
output of a bistable stage 25 which is shown in FIG. 3 and will be
described in greater detail in connection with that Figure. The
output of NAND-gate 24 is connected to the input of a second
NAND-gate 26 to whose second input a phototransistor 27 is
connected. This phototransistor is part of the fine positioning
means for the table carrying the diagram and will be described in
greater detail below. The output of second NAND-gate 26 is
connected to the input of the control pulse generator 18. Pulse
generator 18 is thus activated when the correct inputs are present
for the NAND-gates 24 and 26.
Pulse generator 22, counter 17 and counter 20 are all connected to
stop means, here a switch 29 which is closed by the operator of the
apparatus when the minimum involuntary muscle movement is observed.
Operation of switch 29 causes pulse generator 22 to be
disconnected, and counters 17 and 20 to be deactivated and reset to
zero. Alternatively (by switching a selector switch 29 from the
position shown in FIG. 2 to a position connecting terminal b of
said switch to the remainder of the circuit), the arrangement can
be automated even further by substituting another embodiment of
stop means, namely automatic sensor means 30 which, as will be
described in more detail below, furnish a pulse upon occurrence of
the muscle contraction. The pulse of course operates exactly as
does the closing of switch 29, but the arrangement 30 does not
require anyone to operate the equipment and observe the
patient.
The above-described arrangement operates as follows:
To start the equipment, switch 23 is closed. This causes pulse
generator 22 to start generating pulses. At this point counter 20
is in its null position which is so arranged that the predetermined
reset counting output terminal carries a I signal. This I signal is
applied to one input of AND-gate 14 and therefore allows this
AND-gate to be conductive for pulses from the second pulse
generator means. These pulses are therefore applied to the input of
counter 20, where they continue to increase the count on said
counter, one unit for each received pulse. The pulses appearing at
the output of AND-gate 14 are also applied to the reverse counting
input of counter 12, where they result in a reverse count of one
unit for each received pulse. Thus counter 12 is reset, until, at
the most, its zero position is reached.
For a predetermined count on counter 20, a O signal appears at the
predetermined reset counting output terminal. This causes AND-gate
14 to be blocked so that no further inputs are received by counters
20 and 12. Further, the O signal at the predetermined reset
counting output terminal of the reset pulse counting means 20
causes counter 16 to be moved to the x.sub.1 position.
The x.sub.1 output signal of counter 16 is used to move a table 31
which is part of the indicating means 28. The signal causes the
table to be moved in a direction perpendicular to the axis of the
lamp bank 32. This lamp bank, as previously explained, carries
lamps 13. For greater clarity, lamps 13 are again shown in the lamp
bank 32. Table 31 has a paper, recording means, which carry the
diagram shown in FIG. 1. The paper is spread upon the table in such
a way that each intersection of the vertical and horizontal lines
is over a hole 33 in the table. Movement of the table in the
direction indicated by the arrow in proportion to the signal
x.sub.1 thus causes the x values to be generated, while the y
value, that is the ordinate, is furnished by the lighting of one of
the lamps 14. Thus when counter 16 is switched to furnish the
x.sub.1 output signal, table 31 is driven by motor 34 into the
position wherein the lamp bank is lined up with the x.sub.1
coordinate shown in FIG. 1. When the table has moved into the
correct position the hole 35 shown in FIG. 2 is lined up with a
light source 37 and a phototransistor 27 and phototransistor 27
thus furnishes a signal to the second input of NAND-gate 26 which
causes this NAND-gate to become conductive for signals furnished by
first NAND-gate 24. The signal from phototransistor 27 is also used
to stop the motor, 34, which moves the table. This will be
described in more detail below. When the zero signal next appears
at the output of counter 20, the control pulse generator means 18
are thus activated. At this point, pulse generator 18 commences to
furnish pulses having a pulse width and pulse intervals determined
by the output of counter 16. To correspond with FIG. 1, the first
pulse width would be one second, and the first pulse interval two
seconds. At this time counter 12 furnishes a y.sub.1 output which
controls the amplitude of the current to be a relatively small
amplitude of, according to FIG. 1, 1 milliamper.
Current pulses are thus applied to electrode 10 having a pulse
width and pulse interval determined by pulse generator 18 and an
amplitude determined by counter 12. A number of identical pulses is
applied to the patient in order that any muscle action may be
observed before a higher amplitude current is used. The reaction
time of the observer observing the patient, if such be present,
must of course also be taken into consideration. Thus counter 17
counts the pulses furnished by pulse generator 18 and furnishes a
counter advance signal to counter 12 only after a predetermined
number of identical pulses has been applied to electrode 10 and
thus to the muscle of the patient. Only when counter 17 has reached
a predetermined counting output, which, in turn, is determined by
the state of counter 16, and no muscle twitching has been observed,
is a counter advance signal applied to counter 12, thereby
increasing the amplitude of the current pulses applied to the
patient. From FIG. 1 it is seen that when the counter 12 furnishes
a count y.sub.2, the amplitude of the current in the pulses applied
to the patient is 1.5 miliamps. Simultaneously with the furnishing
of the counter advance signal to counter 12, counter 17 is reset.
Further, the change in the count on counter 12 of course causes a
different lamp 13 to light. Specifically of course the next lamp
following the lamp activated by output y.sub.1 will light. Again a
predetermined number of identical pulses is furnished until counter
17, in the absence of a muscle twitch, again advances counter 12.
The amplitude of the current pulses applied to the muscle of the
patient is increased until the minimum muscle movement is observed
and the operator of the machine operates stop switch 29 or,
alternatively, the automatic stop means 30 are activated by the
twitching of the muscle. This causes pulse generator 22 to be
deactivated and counters 17 and 20 to be deactivated and reset to
zero. The place on the paper may now be marked under which the lamp
13 is lit. This first measured value which was obtained from pulses
having a pulse width of one second and an interval of two seconds
is, as mentioned above, designated the rheobase.
For generating the next pulse on the diagram switch 23 must again
be activated. The previously reset counter 20 is furnished pulses
through AND-gate 14 for a forward counting operation, while counter
12 is simultaneously reset an equal number of steps. Counter 12 may
not be reset all the way to the value of y.sub.1 in order to speed
the measuring process. The number of steps that counter 12 is reset
is so chosen that one is absolutely certain that the minimum muscle
twitching will be observed. Experience has shown that it is
sufficient to reset counter 12 by approximately six steps, since
this will result in a current pulse amplitude which does not as yet
cause muscle twitching. Reference to FIG. 1 will show that for
rectangular pulses the curve starting at the rheobase value at
first is substantially horizontal.
When counter 20 has again reached the position wherein a zero
signal appears at the predetermined reset counting output terminal,
the resetting of counter 12 is stopped and counter 16 is advanced
by one step. This again causes motor 34 to be activated and table
31 to be moved to the next position. Again, the signal from
photo-transistor 27 serves as a fine positioning signal which stops
the motor and causes pulse generator 18 to be activated as
described above. The holes 35 in the table of course are bored in
such a manner that each of the holes indicates the correct
positioning in the x direction. Thus line x.sub.2 will be directly
aligned with the lamp bank when the next signal appears on
phototransistor 27. The pulse width furnished by pulse generator 18
now is the pulse width and pulse interval determined by count
x.sub.2 on counter 16. This is a shorter pulse width and possibly
also a shorter pulse interval. Again, pulses are applied to the
patient with the pulse width and interval determined by pulse
generator 18. Again, the amplitude of the pulses depends upon the
output of counter 12. This amplitude is increased as stated
previously after a predetermined number of identical pulses has
been applied to the patient. Upon observance of the minimum muscle
movement either the response of stage 30 or the closing of switch
29 causes the counters and pulse generators to be reset and
deactivated as stated above. The lamp lit along the line x.sub.2
then indicates the value of y which is to be entered on the
diagram. This process is then repeated for other points in FIG.
1.
In order to find the value required for the chronaxie, the
procedure is the following: As mentioned above, pulses of twice the
amplitude as the rheobase are applied to the muscle and the pulse
width is increased until the minimum muscle twitching appears.
The portion of the apparatus for carrying out this procedure is
shown in FIG. 3. First, start switch 38 is activated, causing
bistable circuit means 25 to switch to the second stable state.
Switching the bistable circuit means 25 also causes counter 16 to
be advanced to its end count, namely count x.sub.14, at which the
minimum pulse width is furnished by pulse generator 18. The output
at counter terminal x.sub.14 causes the motor to be energized,
thereby moving table 31 into the position wherein point x.sub.14 is
lined up with the lamp bank. The amplitude of the pulses applied to
the patient is so adjusted that it is double the amplitude as was
obtained by the rheobase measurement. Activation of the pulse
generator 18, following correct position of the table, then causes
short pulses to be delivered to the patient. Again, a predetermined
number of equal pulses is applied to the patient until the count on
counter 16 is changed. As previously stated enough time must be
allowed, especially if the stop is manually operated, to allow the
observer to see the muscle movement and to react thereto.
The number of so-applied equal pulses depends upon the count on
counter 16. This is accomplished by providing a counter 39 which
counts the number of pulses furnished by pulse generator 18. The
counter is preset to a number corresponding to the count on counter
16. When counter 39 reaches zero, it furnishes a pulse to counter
16 which causes this counter to count backwards by one unit.
Simultaneously, counter 39 is again set to its initial condition
corresponding to the new count on counter 16, causing pulse
generator 18 to deliver a corresponding number of equal pulses
having a slightly longer pulse width than the previously applied
pulses. If no muscle movement is observed, the procedure is
repeated until such muscle movement is observed, switch 29 is
activated or unit 30 responds. The point on the diagram determined
by the positioning of table 31 and the lighting of one of the lamps
13 can then be entered into the diagram.
The apparatus has a "repeat" key which causes the whole process to
be repeated automatically for any desired point, so that the
obtained values may be checked.
The individual units shown in FIGS. 2 and 3 and their
interconnection will now be described in greater detail with
reference to FIGS. 4-9.
FIG. 4 is a circuit diagram of control pulse generator means 18,
pulse generator 18 comprises a monostable multivibrator having
transistors 40 and 41. The base of transistor 40 is connected to
the collector of transistor 41 by means of a capacitor 42, while
the base of transistor 41 is connected to the collector of
transistor 40 by means of a resistor 43. Base of transistor 40 is
connected through a resistor 44 to the common plus line 45, while
the emitter of transistor 40 is connected to the common minus line
46. The collector of transistor 40 is connected through a resistor
47 to the plus line 45. The emitter of transistor 41 is also
connected to the plus line 45 and the collector of transistor 41 is
connected to the minus line 46 by means of a voltage divider
comprising resistors 48 and 49. The collector-emitter circuit of a
switching transistor 50 is connected in parallel to the
base-emitter circuit of transistor 41. The base of transistor 50 is
connected to the positive line through a resistor 51 and is also
connected to the base 2 of a unijunction transistor 52, whose first
base is connected to minus line 46. The emitter of unijunction
transistor 52 is connected to a terminal 56. Terminal 56 is
connected to the collector of a transistor 54 whose emitter is
connected to minus line 46. Terminal 56 is also connected to one
terminal of a capacitor 55 whose other terminal is connected to
minus line 46. The collector of a transistor 53 is also connected
to terminal 56, while its emitter is connected to the plus line
through a resistor 59. The base of transistor 53 is connected to
the tap of a voltage divider comprising a Zener diode 57 and a
resistor 58. The output of second NAND-gate 26 is applied to the
base of transistor 54.
The operation of the above-described pulse generator 18 is as
follows:
When a O signal appears at the output of second NAND-gate 26, which
signal has approximately the potential of minus line 46, then
transistor 54 is blocked and capacitor 55 is charged through the
collector-emitter circuit of transistor 53 and resistor 59. The
current charging capacitor 55 of course is determined not only by
resistor 59 but by the voltage divider ratio of the voltage divider
having Zener diode 57 and resistor 58. Under these conditions
transistors 40 and 41 of the monostable multivibrator are in the
conductive state so that substantially the full positive potential
appears at the collector of transistor 41 and thus at the
right-hand electrode of capacitor 42. Similarly, the left-hand
electrode of capacitor 42 is the potential determined by the minus
line 46. When the voltage across capacitor 55 reaches a
predetermined value, the internal base resistance of double base
diode 52 is greatly reduced for a short time and capacitor 55
discharges through double base diode 52. Thus a negative pulse is
applied to the base of transistor 50, causing this transistor to be
switched to the conductive state. This in turn causes the base of
transistor 41 to receive a positive signal, blocking transistor 41.
This causes the potential at the collector of transistor 41 and
thus at the right-hand electrode of capacitor 42 to become
substantially equal to the negative potential available on line 46.
The voltage on the left-hand electrode of capacitor 42 is still
more negative than this value by approximately the operating
voltage. Thus transistor 40 is also blocked and remains blocked
until capacitor 42 has recharged through resistor 44 to such a
point that the potential on the left electrode is sufficient to
switch transistor 40 to the conductive state. This causes
transistor 41 to become conductive again also and capacitor 42
recharges to its original potential.
The above-described process is repeated when the voltage across
capacitor 55 again has reached the value for causing unijunction
transistor 52 to become conductive. The voltage generated at
terminal 56 to have a substantially exponential form. Corresponding
to this exponential form, the output shown at terminal 60 and
terminal 61 is a rectangular pulse sequence, the amplitude at
terminal 60 being approximately twice the amplitude appearing at
terminal 61.
Changes in the pulse width and the pulse interval of the pulses are
accomplished by changing the resistors and the capacitors in the
above-described circuit. The pulse width depends at least in part
on the values of resistors 59 and capacitors 55, while the pulse
interval depends at least in part on the value of resistor 44 and
capacitor 42. How these are changed will be shown in the
description of FIG. 6.
With reference to FIG. 5, it will now be shown how the amplitude of
the pulses applied to the patient is made to vary as a function of
the output of counter 12. FIG. 5 shows the circuitry required for
this purpose. Specifically, FIG. 5 shows the amplitude control
circuit means, namely transistors 62 and 63 and the associated
resistors as well as output switch means 60 and the symbolically
shown electrode 67. Transistors 62 and 63 serve only as an
illustration. A much larger plurality of such transistors would of
course be used, namely one for each counting output of counter 12.
Specifically, the emitters of transistors 62 and 63 are connected
in common to the minus line 46, while the collector of transistor
62 is connected to the emitter of a transistor 66 constituting
output switch means through a resistor 64 while the collector of
transistor 63 is connected to said emitter via a resistor 65. The
collector of transistor 66 is connected to the electrodes shown in
symbolic form as a resistor 67 to the voltage source denoted by
U.sub.2. The output of the pulse generator 18, namely terminal 60,
is applied to the base of transistor 66.
The base of transistors 62 and 63 are connected to the respective
counting outputs of counter 12 through resistors 68 and 69
respectively. Counter 12 may be any conventional counter and
comprise bistable circuits in each counting stage. Further, each
counting output y.sub.1 -y.sub.n is connected to the base of a
transistor 73, 72, etc. through resistors 71, 70 respectively. The
emitters of transistors 73 and 72 are connected to ground
potential, while the collectors are connected to the positive line
through lamps 13. Transistors 73, 72, etc., operate as amplifiers.
Thus when counter 12 furnishes a signal output y.sub.1, transistor
73 becomes conductive causing lamp 13 to light. The lighting of the
lamp thus indicates the state of counter 12. This in turn gives an
indication of the amplitude of the pulses applied to the patient
since transistor 63 is also put into the conductive state by a
signal at terminal y.sub.1 and causes current to flow upon
application of a pulse to the base of transistor 66 which current
depends upon resistor 65. Thus the current flowing through resistor
67 (which symbolizes the muscle of the patient) has an amplitude
depending upon the state of counter 12 and a pulse width and
interval depending upon the output of pulse generator 18. When the
signal at counting output y.sub.1 disappears and the signal at
counting output y.sub.2 appears, the amplitude of the current is
determined by resistor 64, since transistor 62 will then be
conductive.
FIG. 6 shows the circuitry which is required to change the pulse
width and interval in dependence on the count of counter 16. It
should be noted that terminals a, b, c and d in FIG. 4 are the same
as those shown in FIG. 6. The top line of FIG. 4 is the plus line,
while the bottom line is ground potential. Referring now to FIG. 6,
it is seen that the outputs x.sub.1, x.sub.2 . . . x.sub.m of
counter 16 are connected in pairs to the inputs of OR-gates 74
whose outputs are connected through base resistors 75 to the bases
of transistors 76. Although only two transistors 76 are shown for
each element which may be varied (capacitor 55, resistor 59 and
resistor 44) more of such transistors and associated elements may
of course be furnished. In any case each count on counter 16
results in the energization of at least one OR-gate 74 for each of
the above-mentioned elements. When a positive signal is passed
through the OR-gate 74, the associated transistor 76 becomes
conductive connecting the associated element (for example 55') into
the circuit. Since elements 59 and 44 do not have any connection to
ground potential, an additional transistor 76' must be provided for
each of these components. Specifically, the transistor 76 which is
associated, for example, with resistor 59', has a voltage divider
circuit in its collector circuit. Connected to the tap of the
voltage divider is the base of a transistor 76' whose
emitter-collector circuit is connected from the positive line
(terminal b) to one terminal of resistor 59' whose other terminal
is connected to point a of FIG. 4. When transistor 76 becomes
conductive, the voltage at the base of transistor 76' drops causing
this transistor also to become conductive. This of course connects
element 59' into the circuit of FIG. 4. Resistors 44' are connected
into the circuit of FIG. 4 in the same fashion, except that the
switching transistor which switches these between points d and c in
FIG. 4 is labelled 76" in FIG. 6. It best becomes evident that with
a circuit such as shown in FIG. 6, the width and the interval
between the pulses furnished by pulse generator 18 as shown in FIG.
4 may be varied over extremely wide ranges.
FIG. 7 shows one embodiment of the automatic stop means labelled
stage 30 in FIGS. 2 and 3. The circuit shown in FIG. 7 shows a
capacitive pickup 77 which is connected to the patient. The pickup,
denoted by capacitor 77, forms part of a voltage divider whose
other portion is embodied in a resistor 78. The voltage divider tap
of this voltage divider is connected to the emitter of a field
effect transistor 79 whose output is smoothed by a low pass filter
80. The output of low pass filter 80 is in turn connected to the
input of a threshold stage 81. When the threshold of threshold
means 81 is passed, threshold circuit 81 furnishes the proper
signal for deactivating pulse generator 22 and counters 17, 20 and
39. This signal of course results when the signal at the input of
field effect transistor 79 changes due to muscle contraction in the
patient.
FIG. 8 shows the control circuit for controlling motor 34 which
drives table 31. The direction of rotation of motor 34 is
determined by the setting of a switch 34'. The remainder of the
circuit is used to start and stop the motor. Specifically, both the
forward and the reverse counting input of counter 16 are connected
to the input of an OR-gate 82 whose output is connected to the
switching input of a monostable multivibrator 83. An output of
monostable multivibrator 83 is connected through a resistor 84 to
the base of a transistor 85 whose emitter-collector circuit is
connected in series with a resistor 86 and a light source 37, here
a gallium-arsenide light emitting diode, the so-formed series
circuit being connected from ground to the positive line. The
emitter-collector circuit of a phototransistor 27 is connected to
plus line 45 by means of a resistor 87 and is further connected to
the base of a transistor 89 through a resistor 88. The
emitter-collector circuit of transistor 89 is connected from
positive line 45 to ground. Transistor 89 forms part of a bistable
stage which also includes transistor 90 and resistors 91 and 92.
Specifically, resistor 91 is connected from the base of a
transistor 89 to the collector of the transistor 90, while resistor
92 is connected from the collector of transistor 89 to the base of
transistor 90. Further, the emitter-collector circuit of a
transistor 93 is connected between the base and emitter of
transistor 90, the base of transistor 93 being connected to the
collector of transistor 85. The emitter of transistor 90 is
connected to ground potential, while its collector is connected to
the coil of a relay 91 whose other terminal is connected to plus
line 45. Relay 91 controls contacts 95 which, when closed, short
circuits motor 34. The above-mentioned switch 34' which determines
the direction of rotation of motor 34 is connected in parallel with
said motor and contacts 95.
The above-described circuit operates as follows:
When a pulse is received at either the forward or reverse counting
input of counter 16, that is when the count on counter 16 is
changed in either direction, this pulse is transmitted through
OR-gate 82 to the monostable multivibrator 83, thereby switching
this monostable multivibrator to the unstabled state. At this time,
transistor 85 is blocked, blocking the current flow through diode
37 and therefore causing diode 37 to stop the emission of light.
Therefore, no more light is received by phototransistor 27 and this
transistor blocks. However, the blocking of transistor 85 has
caused a positive potential to be applied to the base of transistor
93, causing this transistor to become conductive. This causes a
negative potential to be applied to the base of transistor 90
causing this to block. Therefore, relay 91 is deenergized and
contacts 95 open. Motor 34 will commence to run in the direction
indicated by switch 34. This causes table 31 to move until a hole
35 in the rod 36 affixed to table 31 causes light to be transmitted
from diode 37 to phototransistor 27. It should be noted that the
time constant of monostable stage 83 is so arranged that diode 37
is again energized prior to the time that the next hole is
positioned in front of diode 37. Thus phototransistor 27 becomes
conductive and a negative signal is applied to the base of
transistor 89 causing transistor 89 and, therefore, transistor 90
to become conductive. Thus current again flows through the coil of
relay 91 causing contacts 95 to close thereby stopping motor
34.
The interconnection between counters 16, 17 and 12 is shown in FIG.
9. Two flip-flop stages 103 and 104 of counter 16 are shown.
Flip-flop stage 103 has an output 110 and a second output 111 while
flip-flop stage 104 has an output 112. Counter 17 further comprises
two AND-gates, 107 and 108, two OR-gates 105 and 106, and a further
AND-gate 109. The output of gate 109 furnishes the counter advance
signal to counter 12. Specifically, this signal is furnished on a
line 114 and it must be noted that counter 12 advances each time
the signal on line 114 changes from a zero to a one state.
AND-gates 107 and 108 each have a plurality of inputs connected
with specific counting stages of counter 16 as will be discussed
below. The output of AND-gate 107 is connected to one input of
OR-gate 105 whose other input is connected to output 110 of
flip-flop 103. Similarly, the output of AND-gate 108 constitutes
one input of OR-gate 106 whose other input is connected to output
112 of flip-flop 104. The outputs of OR-gates 105 and 106
constitute the inputs to AND-gate 109 whose output, as discussed
above, constitutes the counter advanced signal when changing from a
zero to a one state.
The above-described arrangement operates as follows:
Initially it is assumed that counter 16 has a specified output at
output x.sub.1, that is for example a zero potential output. This
indicates that two identical pulses are to be applied to the
patient before any changes in amplitude occur. Pulse generator 18
(after depression of key 38) delivers a pulse sequence 116 to the
input 102 of counter 17.
Initially output 110 of flip-flop 103 carries a I signal, output
111 a zero signal and output 112 of flip-flop 104 also carries a I
signal. Only output x.sub.1 of counter 16 carries a zero signal,
that is outputs x.sub.2 . . . x.sub.m all have a "1" potential.
Thus the output of AND-gate 104 is a "1" potential which does not
serve to advance counter 12, as stated previously, this counter
responds only to changes from "0" to "1" on line 114.
As shown in FIG. 9, the first pulse in the first sequence 116 has a
trailing edge 115. This trailing edge 115 causes flip-flop 103 to
flip, that is output 110 now carries a "0" output, while output 111
is fliped from the "0" to the "1" state. The state of flip-flop 104
is unchanged since this flip-flop reacts only to a change from "1"
to "0." Both inputs of OR-gate 105 thus have a "0" signal which
causes a "0" signal to appear at its output in turn causing a "0"
signal to appear on line 114. Counter 12 is not sensitive to change
of state from "1" to "0." The trailing edge 117 of the second pulse
in pulse sequence 116 again causes flip-flop 103 to flip. Output
110 therefore changes from a "0" to a "1" state while output 111
changes from a "1" to a "0" state. OR-gate 105 receives a "1"
signal from output 110 and therefore furnishes a "1" signal to
AND-gate 109. Flip-flop 104 is sensitive to the change from "1" to
"0" experienced at output 111 and therefore also changes state,
that is output 112 changes from "1" to "0." Since its second input
still carries a "1" signal, OR-gate 106 continues to furnish a "1"
signal to AND-gate 109 causing the signal on line 114 to change
from a "0" to a "1" state, thereby advancing counter 12 by one
step.
Thus counter 12 is advanced for every other pulse in pulse sequence
116. Once counter 16 has passed counting stage x.sub.4, all outputs
x.sub.1, x.sub.2, x.sub.3 and x.sub.4 carry a positive potential
which cause AND-gate 107 and therefore OR-gate 105 to furnish a 1
signal without interruption. During the four subsequent pulses in
pulse sequence 116 one of the outputs x.sub.5 . . . x.sub.8 has a 0
potential. Thus the signal on line 114 will remain at 0. Following
the fourth pulse flip-flop 104 changes state, causing a 1 signal to
appear at output 112, which in turn causes a 1 signal to appear at
the output of OR-gate 106 and on line 114. This change from 0 to
one on line 114 causes counter 12 to advance by one step. FIG. 9
thus illustrates how the given number of pulses applied to the
muscle at any amplitude as determined by the state of counter 12
depends upon the counting state of counter 16. FIG. 9 only shows
two stages of counter 17. Of course further stages will be required
in a practical case.
The interconnection between 18 and 16 and 39 of course can be
carried out in an analogous fashion. Under those circumstances the
counter indicated as counter 17 in FIG. 9 would correspond to
counter 39 of FIG. 3. The output of AND-gate 109 would be connected
to the counting input of counter 16, whose outputs x.sub.1 . . .
x.sub.m would be connected to AND-gates 107 and 108 as in FIG.
9.
It will be noted that the indicating arrangement shown in the
drawing and comprising table 31 which is moved perpendicular to the
axis of a lamp bank 32 constitutes only one possible embodiment. It
is of course equally possible to record the results of the
measurements by means of known x-y recorders, the count on counter
12 constituting one coordinate while the count on counter 16
constitutes the other coordinate of a measuring point. Further, the
points can be indicated by a field of light sources in which every
possible point, namely all the intersections of lines x.sub.1 to
x.sub.n with lines y.sub.1 to y.sub.n are represented by a lamp.
Logic circuit means can then be used to cause that particular lamp
to light up which has the coordinate x.sub.1 corresponding to the
count of counter 16 and the coordinate y corresponding to the count
on counter 12.
While the invention has been illustrated and described as embodied
in a specific indicator and counting circuit, it is not intended to
be limited to the details shown, since various structural and
curcuit changes may be made without departing in any way from the
spirit of the present invention.
Without further analysis, the foregoing will so fully reveal the
gist of the present invention that others can by applying current
knowledge readily adapt it for various applications without
omitting features that, from the standpoint of prior art fairly
constitute essential characteristics of the generic or specific
aspects of this invention and, therefore, such adaptations should
and are intended to be comprehended within the meaning and range of
equivalence of the following claims.
* * * * *