U.S. patent number 3,858,581 [Application Number 05/375,955] was granted by the patent office on 1975-01-07 for medication injection device.
Invention is credited to Dean Kamen.
United States Patent |
3,858,581 |
Kamen |
January 7, 1975 |
MEDICATION INJECTION DEVICE
Abstract
A medication-administering device controlled for repetitive
delivery, by intravenous injection or otherwise, of predetermined
syringe volumes of said medication at present time intervals,
wherein the syringe plunger medication injection stroke is achieved
using a powering motor, and the control exercised over the mode of
operation of the device is related to the rotational traverses of
said motor. This minimizes non-uniform performance and other
shortcomings which characterize prior art medication injection
devices in which the performance of the powering motors are
vulnerable to variances due to varying line voltage, changing work
loads (i.e. medication with different viscosities) and the
like.
Inventors: |
Kamen; Dean (Rockville Centre,
NY) |
Family
ID: |
23483067 |
Appl.
No.: |
05/375,955 |
Filed: |
July 2, 1973 |
Current U.S.
Class: |
604/155;
128/DIG.1 |
Current CPC
Class: |
A61M
5/1456 (20130101); Y10S 128/01 (20130101) |
Current International
Class: |
A61M
5/145 (20060101); A61m 005/20 () |
Field of
Search: |
;128/2R,2.5R,218R,218A,214E,214F,DIG.1,234,236 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Truluck; Dalton L.
Attorney, Agent or Firm: Bauer & Amer
Claims
What is claimed is:
1. A medication injection device comprising a syringe for
dispensing medication in accordance with linear displacement of a
plunger thereof, means secured to said syringe for connection to a
patient for dispensing said medication to said patient, a
rotatively mounted lead screw with threads of uniform pitch
disposed in substantially parallel relation to the linear
displacement path of said syringer plunger, pushing means mounted
on said lead screw for advancement therealong in pushing engagement
with said syringe plunger, a motor operatively arranged to power
said lead screw in rotation to cause advancement of said pushing
means and corresponding linear displacement of said syringe
plunger, a radially oriented striker mounted on said lead screw, a
pulse-emitting switch located adjacent said lead screw in the path
of the rotational traverse of said striker so as to be engaged
thereby to cause an emission of an electrical pulse during each
rotation of said lead screw, and a pulse-counting means
electrically connected to receive the transmission of each
aforesaid pulse and operatively connected to permit the operation
of said motor for the duration of the transmission thereto of a
selected number of said ppulses, whereby medication is dispensed in
accordance with the linear displacement of said syringe plunger as
a function of the number of rotational traverses of said lead screw
as counted by said pulse-counting means.
2. A medication injection device as defined in claim 1 including an
additional timing means operatively connected to said motor to
cause the commencement of the operation thereof after a selected
interval of non-operation, whereby said medication is dispensed by
said device in accordance with a selected schedule of successive
intervals of operation and non-operation of said motor.
3. A medication injection device as defined in claim 2 including a
clutch interposed in the drive connection between said motor and
said lead screw, and including means mounting said lead screw for
selected limited linear movement for disengaging the same from said
clutch to thereby terminate the powering rotation of said lead
screw by said motor, whereby said dispensing of medication by said
device is capable of being terminated in an emergency
situation.
4. A medication injection device as defined in claim 2 wherein said
additional timing means is of the type operated by pulses
transmitted to it as is also said pulse-counting means, and further
including a visual signaling device connected to be operated by
each pulse being transmitted to said additional timing means and to
said pulse-counting means, whereby the operation of said visual
signal device is effective in indicating the working condition of
said medication injection device.
5. A medication injection device as defined in claim 4 including a
scale calibrating linear displacement of said syringe plunger with
an ascending number of pulses produced during said rotational
operation of said motor, whereby the volume of medication to be
dispensed can be readily related to a selected number of pulses as
counted by said pulse-counting means.
Description
The present invention relates to improvements in a medication
injection device, and more particularly to an automatic
medication-injecting or administering device readily capable of
dispensing medication in accordance with any selected schedule of
successive intervals of operation and non-operation of a
syringe-driving or powering motor.
Motor driven syringes for medication injection service are already
known, being described and illustrated in U.S. Pat. Nos. 3,456,649
and 3,623,474, as well as in other patents. None of these prior art
devices are readily capable of repetitive deliveries of selected
volumes of medication, i.e., of delivering 2 cc's of a medication
every 2 hours for an 8-hour period, thereby performing four such
deliveries, or otherwise operating on a schedule requiring
repetition. Instead, each such prior art device is limited in
service to a one-time delivery of a seclected volume of medication,
during which a motor merely drives the syringe plunger entirely
through a selected linear displacement causing exiting flow of the
medication from the syringe barrel.
Moreover, any attempt to achieve repetitive performance from any of
the aforesaid prior art devices would be extremely difficult
because of the limited controls that they can accommodate. In the
syringe device of U.S Pat. No. 3,456,649, for example, the
mechanical components partake of linear movement during its
operation and thus, to achieve repetitive service, there would be
required limit switches or the like, adjustable in position along
the path of said linear movement, to start and stop operation of
the device as a function of engagement or physical contact that is
established with these limit switches. This concept of control is
expensive and complicated, and also vulnerable to malfunction in
the event of failure to establish operating contact between a
moving part and a control switch. This, in turn, could result in
the delivery or administration of an overdose of medication,
thereby endangering the patient's health.
Broadly, it is an object of the present invention to provide an
improved medication injection device overcoming the foregoing and
other shortcomings of the prior art. Specifically, it is an object
to provide a motor driven syringe for medication injection or other
delivery to a patient which is readily capable of repetitive
service, is characterized by uniform performance in each said
repeated cycle, and has a high degree of reliability in achieving
these performance requirements.
A medication injection device demonstrating objects and advantages
of the present invention includes a motor operated in rotation and
operatively arranged to cause linear displacement, and thus a
medication-injection stroke, in a syringe plunger, a pulse
generating means effective to emit a pulse each rotational traverse
of the motor during which said syringe plunger partakes of a known,
uniform movement in its said stroke, and a pulse-counting means
electrically connected to receive the transmission of each
aforesaid pulse and operatively connected to cause the commencement
of the operation of said syringe-driving motor and the continued
operation thereof for the duration of the transmission thereto of a
selected number of said pulses, whereby medication-dispensing
service of said device is controlled as a function of the number of
rotational traverses of said motor as counted by said
pulse-counting means.
The above brief description, as well as further objects, features
and advantages of the present invention, will be more fully
appreciated by reference to the following detailed description of a
presently preferred, but nonetheless illustrative embodiment in
accordance with the present invention, when taken in conjunction
with the accompanying drawings, wherein:
FIG. 1 is a perspective view of a medication injection device
according to the present invention;
FIG. 2 is a plan view of the device illustrating further structural
features thereof, and also illustrating how the volume of the
medication to be dispensed is related to an operating parameter of
the device, namely electrical pulses emitted during its
operation;
FIG. 3 is a side elevational view, taken in longitudinal section,
illustrating internal structural features;
FIG. 4 is an end elevational view, in section taken on line 4--4 of
FIG. 3, illustrating structural features of a pulse generator used
in the device hereof;
FIG. 5 is a partial plan view, in section taken on line 5--5 of
FIG. 3, illustrating further structural features; and
FIG. 6 is a block diagram illustrating the electrical components
used in controlling the operation of the mechanical components of
the device hereof.
Reference is now made to the drawings, and in particular to FIGS.
1-3, which show the general organization of the mechanical parts of
a medication injection device, generally designated 10,
demonstrating objects and advantages of the present invention. As
the name implies, the contemplated use of the device 10 is to
achieve the intravenous injection of selected volumes of
medication, dispensed from a syringe 12, according to a selected
schedule. That is, there are many drugs which cannot be
administered to a patient slowly and uniformly over a prolonged
period, but rather must be administered within a prescribed
comparatively short period, followed by a longer period, when it is
not administered and the patient's body has an opportunity to react
to the administered drug. For example, there are certain blood
anti-coagulants that are best administered frequently, but at
intermittant intervals, in order to produce the desired effect on
the blood. Device 10 can be most advantageously used for this
purpose.
As will be described in detail herein, any selected volume of
medication can be dispensed from the syringe 12 through tubing 15
having at its end, although not shown, a syringe needle or other
implement connected for intravenous delivery of the medication into
the patient. Moreover, as just noted, the time interval, during
which a selected volume of the drug or medication, such as 1 cubic
centimeter or "cc", is to be delivered can be relatively short,
e.g., in less than 1 minute, and the next administration of this
same volume of medication can be arranged to occur in 2 hours, or
after other such interval of time. Thus, assuming that syringe 12
is filled with 6 cc's of medication which has to be delivered 1 cc
at a time every 2 hours, this is readily easy to achieve by proper
setting of the controls of the device 10. Naturally, the values
selected in the previous example can be modified, and the invention
is no way intended to be limited thereto, since it can be just as
easily arranged that 2 cc's of medication be administered every 6
hours, et cetera. The significance of the mode of operation of
device 10 is that it is operational or effective to dispense
medication in accordance with a selected schedule of successive
intervals of operation and non-operation.
In the preferred form of device 10 as illustrated in FIGS. 1-5, the
same includes, as previously noted, a syringe 12 of the type having
a plunger 14, the linear displacement of which dictates the amount
of medication which is dispensed from the syringe chamber 12
through the tubing 15 to the patient. Arranged to cause linear
displacement of the plunger 14 is an upstanding head 16 of a
follower, generally designated 18, which, as best shown in FIG. 3,
has a threaded member which is mounted, as at 20, on a lead screw
22 which is powered in rotation by a motor 24. That is, the motor
24 is operatively connected to power the lead screw 22 in rotation,
said lead screw having threads 26 of of uniform pitch machined
along its length and further being disposed substantially parallel
to the path of linear displacement of the plunger 14, in this
instance being arranged below plunger 14 so that the pushing head
16 is readily adapted to be mounted on an upstanding rod 28
projected through a slot 30 in the top plate 32 of the device
housing 34. An elastomeric closure 36 with a central slit 38 is
appropriately mounted across the slot 30 to prevent dust or other
contamination of the interior of the housing box 34.
Completing the construction of the follower 18, and as is well
understood to prevent rotation thereof simultaneously with rotation
of the lead screw 22, is a body element 40, the forward end of
which is prevented from partaking of rotative movement by being
projected, as at 42, through a bore or opening in a stationary
depending mounting member 44 which also assists in supporting the
previously noted motor 24. In operation, lead screw 22 is driven in
rotation and the threaded member 20 in meshing engagement therewith
is therefore advanced along the length of the lead screw 22.
Naturally, in one direction of rotation of lead screw 22 member 20
is advanced toward the motor 24, and in the opposite direction of
rotation away from the motor 24. Head 16 has movements
corresponding to the member 20, and one said direction of movement
causes it, because of its pushing engagement as at 46 with the end
of the plunger 14, to cause linear displacement of this plunger
within the syringe barrel 12 which, in an obvious manner, results
in the dispensing of medication in accordance with said linear
displacement from the internal chamber of the syringe 12. To hold
the syringe 12 against displacement while the plunger thereof is
being operated by the follower head 16, a laterally extending lip
48, which normally functions as a finger grip, has a portion
disposed in a holding recess 50 of a mounting plate 52
appropriately secured in place on the top plate 32. An L-shaped rod
54 functions as a clamp to hold the syringe barrel against the
mounting plate 52 and, in turn, is held in place by a lock screw 56
which, upon threaded adjustment, engages the flattened surface 58
of the clamp 54.
Although the lead screw and follower drive arrangement has been
used heretofore in producing linear displacement of a syringe
plunger in automatic medication injection devices, in the device 10
hereof, the manner in which control is exercised over the operation
of the lead screw and follower 22, 28, respectively, is unique and
is not known in the prior art nor is it suggested therein.
Specifically, this control consists of using the rotational
traverses of the lead screw 22 as the measure of the duration that
the powering motor 24 is operational. As a consequence, serious
prior art shortcomings are overcome. For example, if the powering
motor in a prior art device is permitted to operate for a selected
interval of time, this still would result in non-uniform volumes of
medication being dispensed since, during the selected interval of
time of motor operation, there could be variations in the line
voltage utilized to energize the motor 24. Also, the work load on
the powering motor could be variable and this also would result in
non-uniform volumes of medication being dispensed. Within any
specified time interval, a prior art motor will cause the delivery
of a greater volume of a less viscous medication than one with a
greater viscosity, and thus to achieve uniform dispensing of
medication with such a prior art device, it is necessary to make an
adjustment in the control to account for the different viscosities
of the medication being dispensed. Still further, after a prolonged
period of use the bearings or other moving parts of a prior art
device would experience wear that would in turn effect its
operation during an interval of operation, and this variation in
frictional resistance would also result in non-uniform volumes of
medication being dispensed. In sharp contrast to the foregoing, it
is therefore one of the unique aspects of the device 10 hereof that
the interval of operation of the powering motor 24 is related to
the number of rotational traverses that occur in the lead screw 22,
irrespective of the time that it takes to achieve these number of
rotational traverses. Naturally, with each rotational traverse of
the lead screw 22, member 20 is advanced a uniform amount dictated
by the pitch of the uniform threads 26, and this uniform
advancement of member 20 also occurs in the pushing head 16 and
thus must, of necessity, also result in a uniform linear
displacement in the syringe plunger 14.
At this point in the description, it is appropriate to indicate how
the volume of medication to be dispensed during each application is
related to the number of rotational traverses of the lead screw 22.
As illustrated in FIG. 2, marked along one edge of the top plate
32, as along edge 60, is a scale, generally designated 62, which is
laid out, starting from 0, in ascending numbers such that said
numbers are located at distances from the starting point 0 which
correspond to the distances of advancement that is produced by the
uniform advance or thread pitch 26, that results from that number
of rotational traverses in the lead screw 22. Thus, taking into
account that with each rotational traverse of the lead screw 22,
member 20 will move the pitch of each thread 26 thereon, it follows
that the linear distance 64 will be achieved with 10 rotational
traverses, and twice that distance with 20 rotational traverses,
and so on. Further, assuming that it is desired to dispense 2 cc's
of medication during each injection period, as clearly illustrated
in FIG. 2, this will require approximately 27 rotational traverses
since, by laying the syringe barrel 12 alongside the scale 62, a
2-cc volume as laid out on the barrel 12 spans the distance from
the 0 point on the scale 62 to a point therealong, designated 65,
which corresponds to point 27 of the scale.
Assuming further that it is desired to dispense these 2 cc's of
medication every 2 hours, there are two timing controls embodied in
the device 10 which are appropriately set to provide the schedule
of medication administration indicated. From what has already been
described, it should be readily appreciated that medication is
administered or delivered to the patient only during operation of
the powering motor 24. The motor-on timer, generally designated 66,
includes, as best illustrated in FIG. 2, two control knobs or
selectors 68 and 70, each being related to a circumferential
display of numbers 72 from 1 to 10. In a manner which will be
better understood subsequently, the 2 cc's of medication previously
discussed which also, as previously discussed, is dispensed by 27
rotational traverses of the lead screw 22, as thus imposed on the
mode of operation of the device 10 by setting the selector 68 at
numeral 2 and selector 70 at numeral 7, the combined effect being a
selection of 27 as the number of rotational traverses which will
occur in the lead screw 22 during each interval of operation of the
powering motor 24.
The other timing device, generally designated 74, is the one which
controls or times the motor-off interval, this timer also including
a selector 76 within a circumferential arrangement 78 of numbers
from 1 to 10. In the example being used to illustrate the mode of
operation of device 10, the interval of non-operation of the
powering motor 24 is to be 2 hours between injections of the
medication, and thus selector 76 is moved in proper relation to
numeral 2 to provide this result. The manner in which this result
is achieved will be explained subsequently.
Reference will now be had to FIGS. 4, 5, in conjunction with FIGS.
1-3, to best explain how the operation of device 10 is controlled
in accordance with the rotational traverses of the lead screw 22.
Specifically, mounted on the end of the lead screw 22 remote from
the powering motor 24 is a radially oriented striker 80 which is
driven in rotation simultaneously with the lead screw 22. As
illustrated best in FIG. 4, mounted adjacent the striker 80, and
more particularly, in the path of the rotational traverse thereof,
is a switch contact arm against which actual physical contact is
made by the striker 80 during each rotational traverse. This
physical contact or abuttment against the switch contact 82 results
in actuation of the switch 84. More particularly, it will be
understood that switch 84 is part of a pulse-generating circuit in
that the actuation thereof is effective to complete this circuit
and, in turn, cause the production and transmission of an electric
pulse to a pulse-counting circuit which may be embodied on a
printed circuit board 86 (see FIG. 3).
As will be explained in greater detail in connection with the
circuit diagram of FIG. 6, the pulse-counting circuit 86 will be
understood to be effective in causing the commencement of the
operation of the powering motor 24 and in causing the continued
operation thereof for the duration of the transmission to it of a
selected number of said pulses, which in the example being
discussed would amount to 27 pulses. This number of pulses or
rotational traverses of the lead screw 22 will result, as already
noted, in linear displacement of the syringe plunger 14 which will
force out of the syringe barrel 12 2 cc's of medication.
On the 27th rotational traverse of the lead screw 22, the
electrical control components of the device 10 are effective in
causing three conditions of operation. The first is the resetting
of the motor-on timer 66 at the 0 setting. The second is the
termination of the operation of the powering motor 24. The third is
the starting of the timing operation of the motor-off timer 74. As
in the case of the motor-on timer 66, the timer 74 is also operated
by the transmission to it of pulses and, in accordance with the
example being discussed, will therefore receive whatever number of
pulses generated, not by the rotation of the lead screw 22, but by
an oscillator of some other source, but which corresponds to the
passage of 2 hours of time, this being the time interval selected
for non-operation of the motor 24.
At the expiration of this 2-hour time interval, the motor 24 will
again commence its operation, and at that time striker 80, by
virtue of actuating switch 84, will again cause a pulse-generating
activity as a function of the rotational traverses of the lead
screw 22 being powered in rotation by the motor 24. When 27 pulses
are again transmitted or counted by the pulse-counting circuit 26,
the operation of motor 24 which results in a medicine-injecting
stroke in the syringe plunger 14 is again terminated. Ultimately,
the final 2 cc's of medication is dispensed from the syringe barrel
12, thus requiring the refilling thereof. To signal this condition,
and as best illustrated in FIG. 5, the follower body 40 has a
laterally extending contact 88 which is arranged to actuate the
limit switch 91 by physically abutting against the contact 92
thereof, thus indicating that the end of the medicine-injecting
stroke 94 is reached.
In addition to the timing controls consisting of the motor-on timer
66 and motor-off timer 74, device 10 also includes a control which
overrides these timing devices and which results in the injection
of medicine, even if not in accordance with the selective schedule.
This permits the injection of medicine or medication in emergency
situations. The control itself includes an accessible push-button
96 which, when depressed, is electrically effective to immediately
start operation of the powering motor 24, even if at that time the
device 10 is under the control of the motor-off timer 74. Device 10
also includes an off-on master switch 98.
Also advantageously included as part of the controls for the device
10 is a visual signal in the form of a blinking light 100. Light
100 is energized by each pulse successively transmitted to the
timers 66 and 78, and thus is effective in indicating operation of
the device 10 during both motor-on and motor-off intervals.
Completing the device 10, and as best illustrated in FIG. 3, is a
safety device feature which disconnects the drive between the motor
24 and lead screw 22 in the event of successive buildup of pressure
which is transmitted in a reverse direction through the tube 15
into the barrel chamber 12 and against the syringe plunger 14. This
buildup of resistance pressure will of course be transmitted
against the pushing head 16 and thus is manifested as a force
tending to push lead screw 22 in a direction away from the motor
24. In response to this force, a clutch 136 of a shaft coupling 90
will break its driving connection between its driving and driven
elements and thus result in discontinuation of the driving
connection between the motor 24 and the lead screw 22. Clearance
for this slight rearward movement of lead screw 22 is provided by
compression of an internal spring 138 as a driving notch 140 in the
end of the lead screw 22 moves relative to a driving pin 142. The
notch and pin drive 140, 142 will be recognized as providing
simultaneous driving rotation of the striker 80 as powering motor
24 drives lead screw 22 in rotation.
Reference is now made to FIG. 6 in which there is illustrated, in
diagramatic form, an exemplary electronic circuit which will be
understood to be laid out and otherwise appropriately embodied on
the printed circuit board 86. The circuit of FIG. 6 will further be
understood to function as the motor-on timer 66 and also as the
motor-off timer 74, in both instances providing a timing function
which utilizes and appropriately reacts to the transmission to it
of an electronic pulse. In effect, this portion of the circuit of
FIG. 6, generally designated 110, provides the pulse-counting
service or function for the device 10 in the manner previously
described. This function, in turn, could be powered by batteries or
by line voltage. That is, the device 10 can be used in strapped
position on the arm of the patient, in which instance it will be
portable and operated by batteries (not shown). Alternatively, it
can be used at bedside, in which instance it would be powered by an
ordinary electrical source. Assuming the latter, the power fed into
the unit operates an electric oscillator or pulse generator 112.
This generator may be any one of several types, being generally a
unit which reaches a selected peak voltage on a selected time basis
and which emits a pulse. The output or pulse from the generator 112
is fed into the counting circuit 110. This counting circuit also
could be any one of several so-called decade counting circuits
readily available from major firms such as RCA or the like.
For present purposes, it is suffice to note that operation of a
decade counter, such as that denominated "First Pulse Counter" and
designaged 114 in FIG. 6, has 10 or more outputs identified by the
numbering from 0 to 10. The operation of the pulse counter 114
contemplates activation of each of these outputs in succession with
each cycle of operation, and then a repeat of this cycle of
operation. Accordingly, output 0 is first activated, then output 1,
then output 2, et cetera. When output 10 is activated, this
completes an electrical connection to a second decade counter,
designated "Second Pulse Counter" and identified by reference
numeral 116, which experiences the same mode of operation just
described in connection with counter 114. Meanwhile, the cycle of
operation of counter 114 is repeated. In effect, therefore, it
takes the completion of the succession of pulses through all of the
10 outputs of the first counter 114 to produce one pulse which is
sent via conductor 118 to the succeeding counter 116. In this
manner, any number of pulses can be counted, it being understood
that any selected number of counters 114, 116 and the like can be
electrically connected to each other so as to function as a timing
device, the two units 114, 116 being used as the motor-on timer 66
to measure the interval of time during which the powering motor 24
of the injection device 10 is operative. Naturally, a greater
number of these units would be used in cooperative relation to
provide the motor-off timer 74.
Continuing with the illustrative example previously referred to,
the selection of 27 pulses for the interval of operation of the
powering motor 24 is thus achieved by arranging the selector 68 so
that the wiper 120 thereof is electrically connected to output 2 of
the second pulse counter 116 and that the selector 70, and more
particularly the wiper 122 thereof, is electrically connected to
the output 7 of the first pulse counter 114. While this may appear
to be reversed, such arrangement provides for motor-on operation
for an interval of 27 pulses. As already explained, to achieve
energization of output 2 of the second pulse counter 116 requires
the transmission to this counter of two pulses, each one of which,
however, requires the energization or pulsing of all ten outputs of
the first pulse counter 114, or in other words 20 pulses. Thus,
when the first pulse counter 114 starts on its third successive
cycle of counting operation and when output 7 is energized on the
seventh transmitted pulse, this results in electrical connection to
the two outputs 2 and 7 electrically connected to the selectors 68
and 70. This, in turn, completes a control circuit 124 which
results in the transmission of a pulse to a motor-off switch 126
which results in termination of the powering operation of the motor
24. It also results in the transmission of a pulse via a conductor
128 to a starter circuit 131 for the motor-off timer 74 which
results in the start in operation of this timer.
It will of course be understood that the wipers associated with the
selectors 68 and 70 could have been rotated to make electrical
connection with other outputs other than the specific outputs
indicated. This is illustrated in FIG. 6 wherein the range of wiper
location is diagramatically illustrated by the path of wiper
movement 130.
It is also illustrated in FIG. 6 that pulse generator 112 also
transmits a pulse via conductor 132 to a reset control circuit 134
which is effective to reset to 0 the motor-off timer 74 at the end
of each interval of non-operation of motor 24. This may be done in
any number of ways. One way, for example, is to have the last pulse
of this interval operate a flip-flop switch. Such switch is a
standard part readily purchased in the open market from such firms
as RCA and the like and operates, as generally noted, such that
upon activation by said last pulse, it completes the circuit to the
motor and at the same time resets the counting circuit at its
original 0 setting. As a result, when the motor operation is
terminated, the counting circuit 110 is in condition to start
counting from 0 again.
It should be readily appreciated from the description of the
mechanical components of the device 10 that the pulse generator 112
during the interval of operation of the motor 24, is controlled in
its pulse-emitting function by the striker 80 which, upon physical
contact with the switch 84 during each rotational traverse of the
lead screw 22, produces a pulse which is counted by the motor-on
timer 66. However, during non-operation of the powering motor 24,
the pulse generator 112 is operated as an oscillator and transmits
pulses also to a counting circuit, such as 110, which performs the
same function during non-operation of the motor as was performed
during its operation. Since the time of non-operation of the
powering motor 24 is considerably longer than the typical interval
required for administration of medication, the pulse-counting
circuit 110 will include more than just two pulse counters 114 and
116. But at least the first two counters of an enlarged arrangement
thereof can be counters 114, 116 to avoid duplication.
The primary use of the device 10 is, of course, for administering a
predetermined volume of medication on a timed schedule. However, it
is not strictly limited to this use, but also may be operated by
monitoring equipment separate and apart from the timing devices 66
and 74 described herein. In other words, assume a cardiac patient
has monitoring equipment to indicate when he is in medical
difficulty. Such monitoring equipment could be used to provide a
pulse which starts the motor 24 in operation and which causes the
injection of the predetermined volume of medication to counteract
the condition sensed by the monitoring equipment as requiring said
medication.
From the foregoing description, it should be readily appreciated
that there has been described herein a unique medication injection
device 10 which is capable of administering medication in
accordance with a selected schedule of successive intervals of
operation and non-operation of the powering motor 24. Moreover,
these intervals are controlled as a function of each rotational
traverse, rather than strictly on a manually timed basis, as is the
practice in the prior art. Thus, the device 10 hereof is not
vulnerable to variations which affect performance during any
selected unit of time, such as variations in voltage, in viscosity
of the medication being dispensed, variations in the frictional
resistance within the motor itself, to mention just a few, and
other such factors which adversely affect and produce
non-uniformity in the functioning of devices of the class herein
described.
A latitude of modification, change and substitution is intended in
the foregoing disclosure, and in some instances some features of
the invention will be employed without a corresponding use of other
features. Accordingly, it is appropriate that the appended claims
be contrued broadly and in a manner consistent with the spirit and
scope of the invention herein.
* * * * *