US3858581A - Medication injection device - Google Patents

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.

Description

United States Patent 11 Kamen Jan. 7, 1975 MEDICATION INJECTION DEVICE Primary ExaminerDalton L. Truluck [76] Inventor: Dean Kamen, 99 Bulsar Rd., Attorney Agent or F'rm Bauer & Amer Rockville Centre, NY. 11570 221 Filed: July 2, 1973 AB TRACT [2l] Appl. No.: 375,955 A medication-administering device controlled for repetitive delivery, by intravenous injection or otherwise, of predetermined syringe volumes of said medi- [52] US. Cl. 128/218 A, l28/DIG. l cation at present time intervals, wherein the Syringe [51] hit.Cl A6lm 5/20 plunger medication injection Stroke is achieved using [58] Fleld ofSearch 128/2 218 R a powering motor, and the control exercised over the 128/218 214 214 236 mode of operation of the device is related to the rotational traverses of said motor. This minimizes non- [56] References C'ted uniform performance and other shortcomings which UNITED STAT S PA NTS characterize prior art medication injection devices in 2,602,446 7/1952 Glass etal. 128/218 A hich the performance of the powering motors are 2,627,270 2/1953 Glass l28/2l8 A vulnerable to variances due to varying line voltage, 3,091,239 5/1963 Moeller 128/214 F changing work loads (i.e. medication with different HObbS A viscosities) and the 3,701,345 10/1972 Heilman et al 128/2R 5 Claims, 6 Drawing Figures MEDICATION INJECTION DEVICE 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 syringedriving 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 ccs 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 patients 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 medicationinjection 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 thedevice 10 is to achieve the intravenous injection of selected volumes of medication, dispensed from asyringe 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 patients 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 thesyringe 12 throughtubing 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 thatsyringe 12 is filled with 6 ccs of medication which has to be delivered I cc at a time every 2 hours, this is readily easy to achieve by proper setting of the controls of thedevice 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 ccs of medication be administered every 6 hours, et cetera. The significance of the mode of operation ofdevice 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 as illustrated in FIGS. 15, the same includes, as previously noted, asyringe 12 of the type having aplunger 14, the linear displacement of which dictates the amount of medication which is dispensed from thesyringe chamber 12 through thetubing 15 to the patient. Arranged to cause linear displacement of theplunger 14 is anupstanding 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 alead screw 22 which is powered in rotation by amotor 24. That is, themotor 24 is operatively connected to power thelead screw 22 in rotation, said leadscrew having threads 26 of of uniform pitch machined along its length and further being disposed substantially parallel .to the path of linear displacement of theplunger 14, in this instance being arranged below plunger 14 so that the pushinghead 16 is readily adapted to be mounted on anupstanding rod 28 projected through aslot 30 in thetop plate 32 of thedevice housing 34. Anelastomeric closure 36 with acentral slit 38 is appropriately mounted across theslot 30 to prevent dust or other contamination of the interior of thehousing box 34.

Completing the construction of thefollower 18, and as is well understood to prevent rotation thereof simultaneously with rotation of thelead screw 22, is abody 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 mountingmember 44 which also assists in supporting the previously notedmotor 24. In operation,lead screw 22 is driven in rotation and the threaded member in meshing engagement therewith is therefore advanced along the length of thelead screw 22. Naturally, in one direction of rotation oflead screw 22member 20 is advanced toward themotor 24, and in the opposite direction of rotation away from themotor 24.Head 16 has movements corresponding to themember 20, and one said direction of movement causes it, because of its pushing engagement as at 46 with the end of theplunger 14, to cause linear displacement of this plunger within thesyringe barrel 12 which, in an obvious manner, results in the dispensing of medication in accordance with said linear displacement from the internal chamber of thesyringe 12. To hold thesyringe 12 against displacement while the plunger thereof is being operated by thefollower head 16, a laterally extendinglip 48, which normally functions as a finger grip, has a portion disposed in aholding recess 50 of amounting plate 52 appropriately secured in place on thetop plate 32. An L-shaped rod 54 functions as a clamp to hold the syringe barrel against themounting plate 52 and, in turn, is held in place by alock screw 56 which, upon threaded adjustment, engages theflattened surface 58 of theclamp 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 thedevice 10 hereof, the manner in which control is exercised over the operation of the lead screw andfollower 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 thelead screw 22 as the measure of the duration that the poweringmotor 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 themotor 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 nonuniform volumes of medication being dispensed. In sharp contrast to the foregoing, it is therefore one of the unique aspects of thedevice 10 hereof that the interval of operation of the poweringmotor 24 is related to the number of rotational traverses that occur in thelead screw 22, irrespective of the time that it takes to achieve these number of rotational traverses. Naturally, with each rotational traverse of thelead screw 22,member 20 is advanced a uniform amount dictated by the pitch of theuniform threads 26, and this uniform advancement ofmember 20 also occurs in the pushinghead 16 and thus must, of necessity, also result in a uniform linear displacement in thesyringe 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 thelead screw 22. As illustrated in FIG. 2, marked along one edge of thetop plate 32, as alongedge 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 orthread pitch 26, that results from that number of rotational traverses in thelead screw 22. Thus, taking into account that with each rotational traverse of thelead screw 22,member 20 will move the pitch of eachthread 26 thereon, it follows that thelinear 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 ccs 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 l2 alongside thescale 62, a 2-cc volume as laid out on the barrel l2 spans the distance from the 0 point on thescale 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 ccs of medication every 2 hours, there are two timing controls embodied in thedevice 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 poweringmotor 24. The motoron timer, generally designated 66, includes, as best illustrated in FIG. 2, two control knobs orselectors 68 and 70, each being related to a circumferential display ofnumbers 72 from l to 10. In a manner which will be better understood subsequently, the 2 ccs of medication previously discussed which also, as previously discussed, is dispensed by 27 rotational traverses of thelead screw 22, as thus imposed on the mode of operation of the device by setting theselector 68 at numeral2 andselector 70 atnumeral 7, the combined effect being a selection of 27 as the number of rotational traverses which will occur in thelead screw 22 during each interval of operation of the poweringmotor 24.

The other timing device, generally designated 74, is the one which controls or times the motor-off interval, this timer also including aselector 76 within acircumferential arrangement 78 of numbers from 1 to 10. In the example being used to illustrate the mode of operation ofdevice 10, the interval of non-operation of the poweringmotor 24 is to be 2 hours between injections of the medication, and thusselector 76 is moved in proper relation tonumeral 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. l-3, to best explain how the operation ofdevice 10 is controlled in accordance with the rotational traverses of thelead screw 22. Specifically, mounted on the end of thelead screw 22 remote from the poweringmotor 24 is a radially orientedstriker 80 which is driven in rotation simultaneously with thelead screw 22. As illustrated best in FIG. 4, mounted adjacent thestriker 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 thestriker 80 during each rotational traverse. This physical contact or abuttment against theswitch contact 82 results in actuation of theswitch 84. More particularly, it will be understood thatswitch 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-countingcircuit 86 will be understood to be effective in causing the commencement of the operation of the poweringmotor 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 thelead screw 22 will result, as already noted, in linear displacement of thesyringe plunger 14 which will force out of thesyringe barrel l2 2 ccs of medication.

On the 27th rotational traverse of thelead screw 22, the electrical control components of thedevice 10 are effective in causing three conditions of operation. The first is the resetting of the motor-ontimer 66 at the 0 setting. The second is the termination of the operation of the poweringmotor 24. The third is the starting of the timing operation of the motor-off timer 74. As in the case of the motor-ontimer 66, thetimer 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 ofthelead 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 themotor 24.

At the expiration of this 2-hour time interval, themotor 24 will again commence its operation, and at thattime striker 80, by virtue of actuatingswitch 84, will again cause a pulse-generating activity as a function of the rotational traverses of thelead screw 22 being powered in rotation by themotor 24. When 27 pulses are again transmitted or counted by thepulsecounting circuit 26, the operation ofmotor 24 which results in a medicine-injecting stroke in thesyringe plunger 14 is again terminated. Ultimately, the final 2 ccs of medication is dispensed from thesyringe barrel 12, thus requiring the refilling thereof. To signal this condition, and as best illustrated in FIG. 5, thefollower body 40 has a laterally extendingcontact 88 which is arranged to actuate thelimit switch 91 by physically abutting against thecontact 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-ontimer 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 poweringmotor 24, even if at that time thedevice 10 is under the control of the motor-off timer 74.Device 10 also includes an off-onmaster switch 98.

Also advantageously included as part of the controls for thedevice 10 is a visual signal in the form of a blinkinglight 100.Light 100 is energized by each pulse successively transmitted to thetimers 66 and 78, and thus is effective in indicating operation of thedevice 10 dur ing both motor-on and motor-off intervals.

Completing thedevice 10, and as best illustrated in FIG. 3, is a safety device feature which disconnects the drive between themotor 24 andlead screw 22 in the event of successive buildup of pressure which is transmitted in a reverse direction through thetube 15 into thebarrel chamber 12 and against thesyringe plunger 14. This buildup of resistance pressure will of course be transmitted against the pushinghead 16 and thus is manifested as a force tending to pushlead screw 22 in a direction away from themotor 24. In response to this force, a clutch 136 of ashaft coupling 90 will break its driving connection between its driving and driven elements and thus result in discontinuation of the driving connection between themotor 24 and thelead screw 22. Clearance for this slight rearward movement oflead screw 22 is provided by compression of aninternal spring 138 as a driving notch 140 in the end of thelead 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 thestriker 80 as poweringmotor 24 drives leadscrew 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 printedcircuit board 86. Thecircuit of FIG. 6 will further be understood to function as the motor-ontimer 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 thedevice 10 in the manner previously described. This function, in turn, could be powered by batteries or by line voltage. That is, thedevice 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 orpulse 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 thegenerator 112 is fed into thecounting circuit 110. This counting circuit also could be any one of several socalled 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 to 10. The operation of thepulse 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, thenoutput 2, et cetera. When output is activated, this completes an electrical connection to a second decade counter, designated Second Pulse Counter and identified byreference numeral 116, which experiences the same mode of operation just described in connection withcounter 114. Meanwhile, the cycle of operation ofcounter 114 is repeated. In effect, therefore, it takes the completion of the succession of pulses through all of the 10 outputs of thefirst counter 114 to produce one pulse which is sent viaconductor 118 to the succeedingcounter 116. In this manner, any number of pulses can be counted, it being understood that any selected number ofcounters 114, 116 and the like can be electrically connected to each other so as to function as a timing device, the twounits 114, 116 being used as the motor-ontimer 66 to measure the interval of time during which the poweringmotor 24 of theinjection 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 poweringmotor 24 is thus achieved by arranging theselector 68 so that thewiper 120 thereof is electrically connected tooutput 2 of thesecond pulse counter 116 and that theselector 70, and more particularly thewiper 122 thereof, is electrically connected to theoutput 7 of thefirst 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 ofoutput 2 of thesecond 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 thefirst pulse counter 114, or inother words 20 pulses. Thus. when thefirst pulse counter 114 starts on its third successive cycle of counting operation and whenoutput 7 is energized on the seventh transmitted pulse, this results in electrical connection to the twooutputs 2 and 7 electrically connected to theselectors 68 and 70. This, in turn, completes acontrol 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 themotor 24. It also results in the transmission of a pulse via aconductor 128 to astarter 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 theselectors 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 ofwiper movement 130.

It is also illustrated in FIG. 6 thatpulse generator 112 also transmits a pulse viaconductor 132 to areset control circuit 134 which is effective to reset to 0 the motor-off timer 74 at the end of each interval of nonoperation ofmotor 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, thecounting circuit 110 is in condition to start counting from 0 again.

It should be readily appreciated from the description of the mechanical components of thedevice 10 that thepulse generator 112 during the interval of operation of themotor 24, is controlled in its pulse-emitting function by the striker which, upon physical contact with theswitch 84 during each rotational traverse of thelead screw 22, produces a pulse which is counted by the motor-ontimer 66. However, during non-operation of the poweringmotor 24, thepulse 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 nonoperation of the poweringmotor 24 is considerably longer than the typical interval required for administration of medication, the pulse-counting circuit will include more than just two pulse counters 114 and 116. But at least the first two counters of an enlarged arrangement thereof can becounters 114, 116 to avoid duplication.

The primary use of thedevice 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 thetiming 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 themotor 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 uniquemedication 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 poweringmotor 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, thedevice 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 nonuniformity 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 con trued broadly and in a manner consistent with the spirit and scope of the invention herein.

What is claimed is:

l. 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 pulsecounting 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 nonoperation, 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 inclaim 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 inclaim 2 wherein said additional timing means is of the type operated by pulses transmitted to it as is also said pulsecounting 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 inclaim 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.

Claims (5)

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.

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