Note: Descriptions are shown in the official language in which they were submitted.
~ ~83~
Thls invention relates to a parenteral administra-
tion set, and more particularly, to an intravenous infusion
set for administering fluid to a patient and the like.
Still more particularly, the invention relates to a disposable
parenteral or intravenous infusion set which has an internal
valve that is electronically controlled to accurately regulate
the rate at which the fluid is fed intravenously to a
patient.
In the prior art, various means have been used to -~ -
control the rate of flow through IV sets for thus regulating
the rate of intravenous administration of fluid to a patient.
For example, manual flow control means have been provided in ; ,
the form of clamps or the like, which are positioned on a
length of IV tubing and are adjusted to pinch ~he tubing to
enable more or less flow through the tubing and thus into the
veins of a patient. Such devices are subject to irregular
operation, however, due to changes in Eluid pressure or due ~ `
to human error in setting the clamps and the like. Elec-
tronically controlled devices have also been utilized,
wherein an external, electromechanically operated valve is
associated with the IV tubing to pinch the tubing and thus
control the rate of flow therethrough dependent upon a
signal from a timer which is preset to give a predetermined ``~
number of signals per unit of time. In such electronically
controlled or operated devices, the circuits are relatively
complicated and expensive, azd the valve means utilized
...,:, ~ .
-2-
~ ~' '
83~1~Z,
pinch or crimp or otherwise deform the tubing to control
flow therethrough, thus substantially increasing the expense
of the units and reducing the reliability thereof. For
example, pinching of the IV tubing results in cold flow of
the tubing with a consequent change in the flow rate there- -~
through. Still other prior art devices use elec~rically
controlled valves which flutter, or operate at some multiple
of the desired drip rate, or internal drop sensing means are
used.
In accordance with the present invention, a solid
state circuit is utllized to control an electromagnetically
operated valve in the IV set to control the rate of flow
therethrough. The set is of the gravity feed type and thus
will not continue to feed fluid in the event the needle
goes through a vein and into the surround mg tissue. The
valve itself is an internal valve operable between open
and closed positions without requiring deformation of the
tubing or other parts of the set, and in one form of the ;,
invention comprises a reciprocating ball member which is
.
normally maintained seated under the action of gravity and ~ ~ -
fluid pressure above the ball to thus prevent flow through - ~
the set and eleetromagnet means are disposed adjacent the ~ ~ ;
ball to lift the ball from its seat whenever a signal is
sent to the electromagnet means by a timer or clock mechanism. ~ ;
The timer generates a plurality of pulses per unit of time
at a constant repetition rate, as determined by the setting
on the clock or timer, and directly corresponding to the
desired number of drops of IV fluid per unit of time.
; Moreover, permanent magnet means are preferably provided on --
the set to hold the valve open in the event of a power
:. ,
-3-
1~133~02
failure or the like, or to ef:Eect ~lushillg of the set, or to transport the
patient from one location to another, and a conventi.onal clamp means may be
used to regulate the flo~ in such event. ~xternal drop detecting means are
also used, thus eliminating completely any penetration or deformation of the
set.
The present invention may be summarised according to a first broad
aspect as an electronically controlled intravenous infusion set, comprising:
a supply of intravenous fluid, a drip chamber connected with said supply;
a length of IV tubing connected with the drip chamber; said drip chamber and
length of IV tubing comprising a fluid flow passage means; valve means conn-
ected in the intravenous inusion set downstream of the supply of IV fluid
within the flow passage means and being operated between open and closed
positions; valve operating means external of the flow passage means and opera~
tive to operate the valve means between open and closed positions to control
flow of IV fluid through the intravenous infusion set; electrical circuit : ~.
means connected with the valve operating means to control operation of the
valve means, said circuit means including a variable timer means having means
to generate a plurality of pulses per unit of time at a constant repetition
rate and directly corresponding to a desired number of drops of IV fluid
per unit of time, a bistable latching flip-flop connected between the timer
means and the valve operating means and operative to maintain the valve ,: :
opsrating means de-energized until a pulse is received from the timer means
and then operative to enable energization of the valve operating means
to open the valve and hold the valve open until a drop falls, drop detector
means operatively associated with the drip chamber to sense a drop falling
through the drip chamber, said drop detector means operatively connected
with the bistable latching flip-flop to reset the flip-flop and thus de- :
energize the valve operating means when a drop is sensed by the drop ;~
detector means to enable the valve to close, and no-drop detector means oper-
atively connected with the drop detector means and with the timer means and
bistable latching flip-flop and operative to indicate a no-drop condition
when a pulse is received from the timer means~)ut no pulse is received from
~33(~(~2
the drop detector means~ and operative to lock the latching flip-10p and
prevent energization of the valve operating means when sa:id no-drop condition
is sensed.
According to another broad aspect, the present invention
providesin an in~ravenous infusion set including a drip chamber adapted to be
connected with a supply of IV fluid and a length of IV tubing connected with
the drip chamber, the improvement comprising an electromagnetically operated
valve means in the drip chamber for controlling the rate of flow through the
intravenous infus.ion set, said valve means comprising an extension on the
lower end of the drip chamber, an axially upwardly facing valve seat in the
extension, a magnetically attractive valve in the extension cooperable with
the valve seat and maintained in closed position under the action of gravity, ;
electromagnet means externally of the drip chamber adjacent the valve to
operate the valve to its open position upon energization of said electro-
magnet means, and electronic control means connected with said electromagnet ~ :
means to operate said electromagnet means to open said valve at predetermined
in~ervals of time to establish a desired drip rate through said drip chamber, ~-
said electronic control means comprising a variable timer means having means
to generate a preset number of pulses per unit of time, a switch means
connected with the timer means and with the electromagnet means and operative
to energize the electromagnet means to open the valve when a pulse is
generated by said timer means and to maintain the electromagnet energized and
hold the valve open until a drop falls, drop detector means operatively
associated with the drip chamber to sense the falling drop and generate a : - ;.
pulse in response thereto, said drop detector means connected with said
switch means to reset said switch means and thus de-energize said electro- ~ `
magnet means and close said valve when said drop falls, and no-drop i
detector means operatively connected with said timer means to receive the ~
pulses therefrom and connected with said drop detector means to receive :;
pulses therefrom when a drop is detected, the ou~put of said no-drop . :~
detector means connected with said switch means, and said no~drop detector
means operative when no drop falls, and two pulses are thus sequentially
4a-
.4 .~ ~:
~3~3~2
received from the timer means in the a~sence o~ an intexvenlng pulse from
the drop detector means, to :inh:ibit the switch means and prevent energization
of the electromagnet means.
According to a further broad aspect, the present invention
provides an electronically controlled intravenous infusion set for use with
a supply of intravenous fluid, comprising: a drip chamber connected with
said supply; a length of IV tubing connected with the drip chamber for
receiving IV fluid from the drip chamber; said drip chamber and length of IV ::
tubing comprising a fluid flow passage means; valve means wi~hin the flow
passage means and operable between open and closed positions; valve operating
means external of the flow passage means and operative to operate the valve ; ~
means between open and closed positions to control flow of IV fluid through . .~ -.
the intravenous infusion set; electrical circuit means connected with the .
valve operating means to control operation of the valve means, said circuit .;~
means including variable timer means having means to generate a plurality - :-
of pulses per unit of time directly corresponding to a desired number of : ~
drops of IV fluid per unit of time, irst switch means connected in the . ~ .
circuit means between the timer means and the valve operating means and :
operative to maintain the valve operating mecms de-energized until a pulse
is received from the timer means and then operative to energize the valve
operating means to open the valve and hold it open until a drop falls, drop
detector means operatively associated with the drip chamber to sense a drop : -.
falling through the drip chamber and generate a pulse in response thereto,
said drop detector means operatively connected with the first switch means
to send the pulse generated upon sensing a drop to the first switch means
to reset the switch means and thus de-energize the valve operating means when :~a drop is sensed by the drop detector means, and no-drop detector means
includin~ a second switch means operatively connected in the circuit means
with the first switch means to send a signal to the first switch means to
inhibit the first switch means and prevent energization of the valve operat~
ing means in the absence of drop pulses between successive clock pulses.
According to ye~ another broad aspect, the present invention
....... . . .
13~83~)2
provi~es an elec~ronically controlled intravenous infusion s~t for use with
a supply of intravenous fluid, said set co~prising in combination, a drip
chamber adapted to be connected wi~h said supply, a length of IV tubing
connected with the drip chamber for receiving IV fluid trom said drip chamber,
said drip chalnber and length of IV tubing comprising a fluid flow passage,
valve means within said flow passage and operable between open and closed
positions, valve operating means external of the flow passage and operative
to operate the valve means between open and closed positions to control flow
of IV fluid through the intravenous infusion set, electrical circuit means
connected with the valve operating means to control operation of the valve
means, said circuit means including variable timer means for generating a
plurality of pulses per unit o time directly corresponding to a desired
number of drops of IV fluid per unit of time, switch means connected in
the circuit means between the timer means and the valve operating means for
e:Efecting energization of the valve operating means alld opening of the valve
means in response to the pulses generated by said timer means, drop detector
means operatively associated with the drip chamber to sense a drop falling
through said drip chamber and produce a signal in response thereto, means
responsive to the signal produced by said drop detector means and operative ~ -
upon said switch means to reset said switch means and thus de-energize the
valve operating means and close the valve means when a drop is sensed by
the drop detector means, and no-drop detector means responsive to the pulses
produced by said timer means and the signal produced by said drop detector
means for detecting the absence of drop pulses between successive clock -
pulses and inhibiting said switch means in response thereto.
The solid state circuit is exceptionally simple and reliable
and is, therefore, substantially more economical than prior art devices and
utilizes both integrated circuits and discrete components. All logic -~
functions are accomplished via integrated circuits, and discrete components
are used to limit and ampli~y current, establish time periods of the
integrated circuits and form bias networks. The integrated circuits used
are conventional N 7473 J-K bistable flip~flops, a conventional monostable
~ -4c-
'~ .
83~C12
flip-flop identified as ~otorola Part No~ C 3803, and conventional 555
integrated circuit chips. The circuit includes a variable clock or timerJ
a drop detector, a pulse shaper, a drop pulse extender, a drop indicator,
a latch, a no-drop detector, a no~drop alarm and a no~drop indicator. ~s
determined by the frequency adjustment of the clock, when a predetermined
interval of time has elapsed, the clock will undergo a negative transition
and send a negative pulse to the latch. This causes the latch to send a
pulse or to generate a forward bias on a transistor switch, which energizes
the electromagnet and thus opens the valve to enable a drop to form in the `-
drip chamber. When the drop fallsJ it is sensed by the drop detector,
which is entirely external of the flow path and which includes light sensi-
tive means optically coupled across the drip chamber so that a falling drop
interferes with the optical coupling, and which
'~ ~ " ,'"'
'' ~''~' '..
', ~, ';~ ~ -
' ~ ~
4d~ ~
,~
. , ,
. . :
~3n(~2
sends a signal to the pulse shaper, wherc the signal is
amplified and squared ~Ip and then conducted to the drop pulse
extender, which extends the width of the pulse to thus result
in energization of ~he drop indicator for a period of time
sufficient to be observed. The pulse shaper also sends a
pulse to the latch or switch means to reset the latch and
remove the bias from the transistor switch to thus de-
energize the valve and enable the valve to close.
The outpu~ of the variable clock is also connected
with the no-drop detector to trigger the no-drop detector,
and an output of the drop pulse extender is also connected ~ -
with the no-drop detector to reset the no-drop detector.
This output of the drop pulse extender undergoes a change of
state substantially simultaneously with the cha~ges of state
of the pulse shaper. Thus, if no drop is detected, the - -
no-drop detector will~not be reset and the output of the ~:
no-drop detector, which is fed to the J input of the latch,
will cause the latch to respond to the next clock pulse by
driving its Q output low, and will thereafter maintain the ;
latch at a "zero" as long as no drops are detected. The
no-drop detector is itself locked up by the drop indicating
output from the drop pulse extender, such that the no-drop
detector will not be energized or change states every time
a signal is received from the clock, which would in turn
enable the latch to be triggered every other cloGk pulse.
The output from the latch and the reset output
from the drop pulse extender are also connected with the
no-drop alarm, such that under normal operating conditions
the output of the drop pulse extender and of the latch will
go negative at the same time, and the no-drop alarm will not
'.~ :
_5_
3~
be triggered, ~md the no-drop inclicator wlll not be turned
on. ~lowever, whencver a no-drop condition occurs, the out-
put from the drop pulse extender will stay at a "one" state,
enabling the no-drop alarm to be triggered on the next
negative transit-ion from the latch, and the no-drop indicator ~ :
will thus be turned on indicating a fault condition.
Further, the drop de~ector includes a pair of photodiodes
or other sensing means disposed adjacent one another on
one side of the drip chamber and accordingly the sensitivity
of the unit is significantly increased, such that in the
event of fogging or the like of the drip chamber wall,
the sensor is s~ill sensitive enough to detect the presence
of a falling drop. Moreover) the use of two sensing means ;
results in a broader field of view and thus a drop can be
detected even though the set may no~ be supported in a true
vertical position. Still further, if one sensor fails, the
other can still sense the presence of a falling drop. ~ ~
Accordingly, with the present invention an s
exceptionally accurate and reliable electronically controlled
intravenous infusion set is provided which is both simple
and economical, and the circuit is maintained in a locked
or latched condition under normal circumstances, and is
~llocked or unlatched for each drop. Moreover, in accordance -
with the present invention, a unique drip chamber has a
valve in the outlet portion thereof for controlling flow
through an IV set provided w-ith the present invention.
Objects of the Invention
It is an object of this invention to provide an
electronically controlled IV set for accurately controlling
:
-6- ~
. ~ : , , . : , ~ ,
1~3~
the rate of flow of fluid being administered intravenously
to a patient, and wherein an internal valve means and
external drop sensing means are provided in the set operative
to control flow through the set in response to a signal pro-
vided ~rom a timer mechanism and operative to control flow
without pinching, penetrating, or otherwis~ deforming the
IV set.
Another object of this invention is to provide
an electronically controlled IV set for intravenous ad- ~-
ministration of fluids to a patient wherein an electro-
magnetically operated valve is provided in the set and a
control circuit is connected with the valve and includes ~;
both integrated circuits and discrete components, with all
logic functions being accomplished via integrated circuits,
and wherein the circuit is operative to maintain the valve
de-energized or latched under normal conditions, and to ~;
unlock or energize the valve for obtaining each drop.
A further object of the invention is to provide a
drip chamber for an IV set, wherein a valve for controlling
flow through the drip chamber is provided in a lower portion
of the drip chamber itself.
Yet another object of the invention is to provide `~
an intravenous infusion set in which an electronically
controlled valve is utilized to control the drip rate
through the set, and wherein magnet means are provided for
holding the valve open to enable flushing of the set or to ~ ~
enable flow even in the event of a power failure or if the ; ~`
patient i~ b.ing transported from one location to another.
_7
~830~2'
: ,
Bricf Description of the Drawings
Figure 1 is a perspective view of a first form of the inv~ntion,
wherein the sensing device is mounted to the drip chamber of an IV set and
the control valve and circuitry therefor ar~ connected with the IV tubing
between the ends thereof.
Figure 2 is an enlarged, exploded view of the drip chamber and
sensing device of the first form of the invention.
Figure 3 is an enlarged, perspective view of the control valve
and a portion of the IV tubing and of the electromagnet means for operating
the valve.
Figure 4 is a greatly enlarged, fragmentary view in section of
the valve and its relationship with the electromagnet means.
Figure 5 is a schematic view of the circuit for the electronic
.~
control of the invention. ~ -
: . ~
Figure 6, appearing on the same drawing sheet as Figure 3, is
a diagrammatic plan view of a first form of photoelectric sensing means in
accordance with the invention.
'~
Figure 7, appearing on the same drawing sheet as Figure 3, is
a chart illustrating the signal relationship of the clock, latch and pulse ~ ~ ;
shaper of the invention.
Figure 8, appearing on the same drawing sheet as Figurè 3, ls
a schematic circuit diagram of a second form of drop detector in accordance
wlth the invention.
Figure 9 is a view similar to Figure 3, of the permanent magnet
means for holding the valve open.
Figure 10 is a schematic view of a second form of electronically
controlled IV set in accordance with the invention, wherein the sensing
device, control valve and circuitry therefor are all positioned on the drip
chamber.
~ .
~ ~,
~ '
~83~1~Z
Figure 11 is a fragmentary, enlarged view in
section of the drip chamber of Figure 10, showing the
position of the valve in relation to the drip chamber.
Detailed Description of the Invention
In the drawings, wherein like reference numerals
indicate like parts throughout the several views~ ~n IV
set is indicated generally at 10 and includes a bottle or
bag or other suitable supply 11 of IV fluid F, suitably
suspended or supported from a hook H carried by an upright
post or support S. A drip chamber 12 is connected to the
bottom of the supply 11 in a conventional manner, and -
typically the drip chamber I2 has a piercing end 12a thereon
which is inserted into the bottom end of the supply ll. A
suitable filter means 13 is preferably provided in the drip
chamber 12 for filtering contamlnants froni the fluid F. A
length of IV tubing 14 is connected with the drip chamber at
one end and is connected with an internal valve means 15
at its other end~ and a second length of IV tubing 16 is
connected at one of its ends with the valve means 15 and at
its other end with a suitable needle or the like 17 for
insertion into the arm or the like A of a patient for intra-
venous administration of fluids to the patient. The drip
chamber and length of IV tubing define a fluid flow passage
means for the IV fluid. -
A suitable electronic control means 18 is operatively
associated with the valve means 15 and is caused to energize
the valve means in response to a preset signal. The control
means 18 is also connected with a suitable photoelectric
sensing means 19 positioned on the drip chamber 12 for
'.
_ g _
~330~Z
sensing a drop of fluid ~ falling through the drip chamber
and sending a signal to the control means to reset it. A
manually operated clamp 20 of substantially conventional
construction is provided on the IV tubing 16.
The photoelectric sensing device or drop detector
19 is preferably of molded plastic and comprises a generally
U-shaped housing 21 having an elongate slot or notch 22
in one side thereof, with a generally U-shaped channel or
groove.23 in the body extending around the notch 22 adjacent
the upper portion thereof. A suitable light source 24 is : :
in the housing 21 adjacent one side of the notch 22, and a
suitable light sensitive means 25, such as a pair of photo-
diodes 25a and 25b or the like, is in the housing 21 at .
the other side of notch 22 in alignment with the light source
24. The provision of a pair of photodi.odes 25a and 25b,
disposed side-by-side on the opposite side of the drip .~
chamber 12 from the light source 24, as seen in Figure 6, ~:
substantially eliminates the danger of an improper or ;;~
erratic reading in the event the drip chamber wall becomes
~ fogged or drops form. on the wall thereof, since the two
photodiodes significantly increase the sensitivity of the
device~ and even in the event of the photodiodes 25a or
25b becoming partially blocked by such fogging or drops
forming on the wall of the drip chamber, the circuit
remains balanced, whereby a drop falling through the drip
chamber will interrupt the beam of light to the photodiode ~ :
and cause a voltage change at the photodiode 25a to thus
generate a signal to operate the device. Further, by using
two photodiodes~ even if the device is not accurately
vertically suspended, the sweep of ~he sensor is such that
a falling drop is still detected, even though it does not
-10- :,
: :
:-. - ~ , , ~ ; ,
. . . : ~ :
~0830~
fall through the center of the device. In use, the drop
detector 19 is mounted to the drip chamber 12 by inserting
the drip chamber into the notch 22 with the flange 12b
at the upper end of the drip chamber received in the
groove 23 in the housing 21, and with the light source
24 and light sensitive means 25 disposed substantially at
diametrically opposi~e sides of the drip chamber 12, so
that a drop falling through the drip chamber will interrupt
the beam of light from light source 24 and cause a voltage
change at the photodiode 25, to thus transmit a signal to
the control means 18.
The control means 18 includes a suitable housing
or control box 26 in which the circuitry is contained,
and an electrically controlled valve operating housing 27a
in which a pair of electromagnets 28 and 29 are disposed on
opposite sides of a slot or notch 30~ which is slightly
enlarged at Its rear side or edge 31 and is constructed in
relation to the size of the valve means 15, such that the
valve means may be inserted through the slot 30 and pulled
downwardly into the enlarged portion 31.
The valve means pTeferably comprises a one-piece,
elongate, plastic, tubular valve housing 32, having a radially ~ -
outwardly directed flange 33 on the upper end thereof, which
is arranged to seat against the upper surface of the housing '~
27a to accurately locate the housing and valve ball 34
contained therewithin relative to the electromagnets 28 ;;~
and 29. The housing 32 is tapered inwardly between its ends
to define an upwardly facing valve seat 35 against which the
~,. : , ,; ::
valve ball 34 seats under the action of gravity and the
pressure of fluicl above the valve, and the lower end 36 of -
"' ;',"'~ ~' '
~ - 1 1 - ~'`' ,. ' '
163133~
the housing is gradually inwardly tapered for reception
thereover of the end of IV tubing 16. The inlet section 14
of IV tubing to the valve 15 is secured within the upper
portion of the valve housing 32J and the lower end of the IV
tubing 14 is abutted against a narrow, annular~ upwardly
facing shoulder 37 in the bore of the upper portion of
housing 32 to correctly space the end of the IV tubing 14
from the ball valve 34.
As seen in Figures l and 9, a permanent magnet or
housing means 27b is also provided on the control unit 18J ;
and is substantially similar to the electromagnet means
27a in Figure 3J except that rather than electromagnets 28
and 29, permanent magnets 28' and 29' are provided. Thus,
if it is desired to flush the setJ the valve means 15 is
merely placed in position in housing 27b and the permanent
magnet means holds the valve openJ and with clamp 20 opened,
full flow is achieved through the set to flush it. Moreover
in the event of a power failure or the likeJ the valve means
15 may be positioned in the permanent magnet housing and the
clamp 20 adjusted to obtain the desired flow rate. Still
~urtherJ if it is necessary or desirable to transfer the
patient from one location to anotherJ the permanent magnet
and clamp can be used to control flow while the patient is
in transit.
The control circuit for controlling operation of ; ~;
the ball valve 34 and thus for controlling the drop rate,
and accordingly the rate of f1OW of fluid through the set,
includes variable timer means 39 having means to generate
a plurality of pulses per unit of time direct~y corres-
ponding to a desired number of drops of IV fluid per unit
of timeJ first switch means 40, 41 connected in the circuit -
'' '' ;~ .
-12-
~0~330~3Z
means bctween the timer means and the valve operating means
and operative to maintain the valve operating means de-
energized Imtil a pulse is received from the timer means and
then operative to energize the valve operati.n~ means to
open the valve and hold it open until a drop falls, drop
detector means 19 operatively associated with the drip
chamber to sense a drop falling through the drip chamber and
generate a pulse in response thereto, said drop detector
means operatively connected with the first switch means to
send the pulse generated upon sensing a drop to the first
switch means to reset the switch means and thus de-energize
the valve operating means when a drop is sensed by the drop
detector means, and no-drop detector means including a
. ~
second swi.tch means 46 operatively connected in the circuit .
means with the first switch means to send a signal to the .
first switch means to inhibit the first switch means and
prevent energization of the valve operating means in the
absence of drop pulses between the successive clock pulses. .
As seen In Figure 5, the drop-detector l9 includes .
a pair of NPN photo transistors Ql and Q2 arranged as a
comparative circuit, and light striking the emitter-base
junctions of the transistors causes current to flow through
the emitter bias resistor R3, the transistors Ql and Q2
and the load resistors Rl and R2.to the supply voltage Vcc. .;
In this conducting state, the collector voltage is low, at .
some point near ground. When the light source is interrupted
by a drop, current flow drops through the circuit and the
collector voltage rises to a level near the supply voltage. .
This action appears as a pulse at the input of the dif- ; .-
ferentiating network, including capacitor Cl and resistor R6. .. ~
-13- ~;`. :
.,. .~'';~'
1~3C~)2
In the event the drip chamber becomes fogged or if droplets
form on the sur~ace of the drip chambei~ wall and such fogging
or droplets reduce the amount of light striking the photo-
transistors ~1 and Q2, the circuit will remain balanced.
A drop falling past the phototransistor will thus cause a
pulse to appear at the input of the differentiating network
and thus at the input to pin 2 of the 555 integrated circuit
chip IC-2 of the pulse shaper 38. 9
A timer or clock 39 also includes a 555 integrated
circuit chip IC-l, having its output pin 3 connected with
clock input pin 5 of J-K bistable flip-flop BS-l of latch 40.
The frequency at which the output of IC-l changes states - ~ :
can be varied by changing the setting of potentiometer P
connected with pins 2, 6 and 7 of IC-l, and thus the drip
rate of the IV set can be varied in accordance with the
change in frequency of the signal from pin 3 of the clock
39. The output of IC-l alternates between a logic "one" and
a logic "zero" and the negative transition of going from a
"one" to a "zero" determlnes when a drop starts to form,
since the negative signal of the clock is conducted to the
input pin 5 of the J-K bistable flip-flop BS-l of the latch
40, and this causes the flip-flop BS-l to change states. In
other words, the ~ output of BS-l is normally a "zero" out
and is fed into the base of a transistor switch 41, which is ;~
connected between a source of power and the electromagnet
means 28 and 29 is normally in a nonconducting state, such
that the electromagnets are normally de energized. A
"zero" on the base of the transistor keeps it turned off.
However, when BS-l changes states, as, for example, when ;
the negative pulse is received at pin 5 from pin 3 of the ~ ~
'; :
-14- ~ ~
108~ 2
clock, the Q output of BS-l goes to a "one" and the
transistor switch 41 is now biased forward, enabling current
to flow from the power supply ~o the electromagnets 28 and 29,
thus opening the valve and Rnabling a drop to form in the drip
chamber 12. When the drop falls, it interrupts the light
path to the photodiodes 25a and 25b in the drop detector
circuit, and this interruption causes a sudden change in the
photodiodes' resistancel resulting in a voltage change that
is capacitively coupled to the input pin 2 of IC-2. Every
time a drop falls, a negative pulse is produced at the
.
output pin 3 of IC-2, and this negative pulse is sent to a ~- -
reset pin 6 of BS-l in the latch 40 to reset the bistable
flip-flop BS-l. The Q output of BS-l now goes back to a
"zero", turning off the transistor switch, which stops the
current flow to the electromagnet, enabling the magnetically
responsive ball or other type valve 34 to seat on its sea~
35 under the influence of gravity and fluid pressure above
the ball. Thus, only one drop at a time can fall, at a
predetermined rate established by the setting of the
~0 potentiometer P of the clock 39. In o~her words, the fluid
,: - ~:-
path of the IV set is opened on the negative transition of s
the IC-l output and is closed on the negative transition
of the IC-2 output, i.e., when a drop falls from the drip
device in the IV chamber. The output of IC-2 in the pulse
shaper is also used to trigger a monoskable multivibrator -~
MS-l in a drop pulse extender 42. This extension of the
. . .:
pulse from the pulse shaper 38 is necessary, since the Q
output of the monostable multivibrator MS-l is used to turn
, .~.
on a light emitting diode 43 in the drop indicator 44 via
an NPN driver transistor 45. If the output of IC-2 was used
,.~ , .
,~
-15- ~ ~
-.~ :
:
8301VZ
directly, the light emitting diode 43 would not be turncd on
long enough to be de~ected visually.
A second J-K bistable flip-flop BS-2 is employed
to detect a no-drop condition, and its clock input pin 1 is
connected to the output pin 3 of IC-l. A connection is also
made between pin 6 of monostable multivibrator MS-l and reset
pin 2 of the bistable flip-flop BS-2 to reset the flip-flop
BS-2 when a pulse is fed from the output Q' of the multi-
vibrator MS-l. The negative transitions of the output Q'
from pin 6 of monostable multivibrator MS-l occur almost
exactly in time wi~h those of IC-2, and accordingly, under `~
normal operating conditions the changing of states of the
bistable flip-flop BS-l and the bistable flip-flop BS-2 will
be coincident. -
Pin 13 of bis~able flip-flop BS-2 in the no-drop
detector 46 is connected with pin 7 of the J input of the
bistable flip-flop BS-l of the latch 40, and in
normal operation will be high, causing the latch 40 to
switch the Q output thereof from a low to a high in response
to each clock pulse. However, when a no-drop condition
occurs, as for example, when the IV bottle is empty or ~/; ;
the tubing is plnched and the like, the flip-flop BS-2 will
not be reset after being triggered by a pulse from IC-l,
thus the Q' output of BS-2 will now stay a~ a logic "zero", ;~
and this "zero"~ applied to the input pin 7 of BS-l, will `~
cause the flip-flop BS-l to respond to subsequent clock
pulses by driving the Q output to a zero and keeping such Q
output at a "zero" as long as no drops are detected.
Further, the bistable flip-flop BS-2 is locked
up by feeding a signal to pin 3 thereof from the Q output ;~
or pin 8 of monostable multivibrator MS-l. If this were
-16-
',, ~, ',
. -. :, " . , . - , -, .. .
3~0Z
not done7 the bistable flip-flop BS-2 would change states
with every ncgative transition from the chip IC-l of clock
39 and bistable flip-flop BS-l of latch 40 would, there~ore,
be triggered every other clock pulse. ~ ;
A no-drop condition is visually indicated by
turning on a light emitting diode 47 in a no-drop indicator
48 via a third bistable flip-flop BS-3 in a no-drop alarm 49.
The clock input pin 1 of BS-3 is connected with the Q output
or pin 9 of BS-l and the reset input of BS-3 at pin 2 is fed
by the Q' output of monostable multivibrator MS-l. Under
normal operating conditions, the Q' output of MS-l and the Q
output of BS-l will go negative at the same time, and when
this happens, BS-3 will not trigger and the no-drop light
emitting diode 47 will not be turned on. However, whenever a
no-drop condition occurs, the Q' output of multivibrator MS-l -~
will stay at a "one" state, enabling flip-flop BS-3 to be
triggered on the next negative transition from flip-flop -~
BS-l. When the flip-flop BS-l is triggered, the no-drop
light emitting diode is turned on, indicating a fault condi-
tion. After the Q output of flip-flop BS-l goes negative,
triggering the flip-flop BS-3, it will remain locked in that
state because of the inhibiting action of the flip-flop
BS-2 in the no-drop detector 46. The unit, under these `~
conditions, will remain locked up until the fault condition ~ i
is corrected.
In the chart of Figure 7, the line tl indicates
the negative transition of a clock pulse, and at this point
the latching flip-flop BS-l goes to logic "one" and the
transistor switch 41 is turned on, enabling the electromagnets
to be energized and a drop, therefore, starts to fall. At - -~
time t2 the drop falls and is detected by the photodiodes
-17-
'': ''~ ~ .- ,
. .
1a)83~:)6~
and a reset pulse from -the pulse shayer resets the latching
flip-flop BS-l and the electromagnets are de-energi~ed. As
can be seen, the signals produced and thus the drip rate of
the set are precise and can be predetermined and controlled
with great accuracy and reliability.
In Figures 10 and 11, a modified form of the invention
is illustrated, and in this form of the invention, the
operation of the components is exactly as described above
and the circuitry is as described above. However, in this
form of the invention, rather than providing the ball valve
means 15 in the length of IV tubing, the ball valve 15'
is provided in ~he lower end of a modified drip chamber l2',
and the electromagnets 28 and 29 are positioned adjacent the
extension on a lower end of the drip chamber 12' to attract
the ball 34 upwardly away from the seat 35 to enable a drop
to form in the drip chamber 12', as described previously.
Thus, the sensing means and electromagnets are housed -
in a member 48, which is preferably sui~ably supported,
and the drip chamber 12' is also operatively positioned
relative to the member 48, so that the drop sensing means `
is positioned ~o sense a drop falling through the drip
chamber and so that the electromagnets are positioned to
raise the ball from its seat.
In Figure 8, a modified sensing means 19' includes
only a single photodiode 25 to sense a falling drop. In
all other respects, the apparatus and operation are as ~i
~.
described previously.
In s~mation, a switch means is connected between
the timer means and the valve operating means and is
operative to maintain the valve operating means de-energized
-18-
,, ~ .. . . .- , .
D~;~
until a pulse is received from the tinler means and then is
operative to energize the valve operating means to open the
valve and hold it open until a drop falls. A drop de*ector
means is operatively associated with the drip chamber to
sense a drop falling through the drip chamber and to
generate a pulse in response thereto, and the drop detector
means is operatively connected with the switch means to
send the pulse generated upon sensing a drop to the switch
means to reset the switch means and thus de-energize the
valve operating means when a drop is sensed by the drop
detector means. A no-drop detector means, including a switch
rneans, is operatively connected with the drop detector means
to receive a pulse therefrom as each drop is sensed, and is
connected with the timer means to receive each pulse there-
from, and is operatively connected with the switch means to
send a signal to the switch means to lock or inhibit the
switch means and prevent energization of the valve operating
, ~ :
means when a pulse is received from the timer means, but no
pulse is received from the drop detector means.
It is clear, therefore, that the no-drop detector
is operative to indicate a no-drop condition when a i
pulse is received from the timer means, bu* nc pulse is
received from the drop de~ector means, and operative to lock ;~
the latching flip-flop and prevent energization of thc
valYe operating means when said no-drop condition is sensed. ~ -
:; :
In other words, the no-drop detector means is operative when
no drop falls, and two pulses are thus sequentially generated
by the timer means in the absence of an intervening pulse `
from the drop detector means, to send a signal to the switch
means to inhibit the switch means and prevent energization
of the electromagnet means.
,:~:~ i,. . .
-19- , . ,,:: ,: ,
:: ''': ', ;' ' .':
.: , :
~083(~0Z
As this inv0ntion may be embodied in several
forms without departing from the spirit or essential
characteristics thereof, the present embodiment is,
therefore, illustrative and not restrictive, since the
scope of the invention is defined by the appended claims
rather than by the description preceding them, and all
changes that fall within the metes and bounds of the claims ~ :
or that form their functional as well as conjointly coopera- : -
tive equivalents are, therefore, intended to be embraced by
those claims. ~;
~' :
- ' ''
,- ,, : ~
,~ ,
. ~, ,
'~
, ' ~. ''
-20-
- ~ -, , , ~ ~ . . .. . .
