Abstract:
A combination hypodermic syringe and needle device in which the needle is retracted inside the syringe after completion of the injection. The device requires only one hand for operation wherein increasing the pressure on the plunger initiates an automatic retraction of the needle into the syringe. In operation, a collet is expanded and a spring biased needle retractor is engaged in response to the forward movement of a plunger. The forward end of the barrel carries a wedge which forces the collet to expand upon forward movement of the collet. A vent located in the plunger allows air to escape from the interior of the plunger as the needle assembly is retracted.

Description:
RELATED PATENTS 
     This application is related to U.S. Pat. No. 5,984,898 issued Nov. 16, 1999 to Garvin and U.S. Pat. No. 5,681,292 issued Oct. 28, 1997 to Tober et al. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to medical syringes including needles. More specifically, the invention relates to a combination device including a retractable needle and syringe which, following a full stroke of the syringe plunger, automatically retracts the needle into the body of the syringe thereby preventing the possibility of needle sticks. 
     BACKGROUND OF THE INVENTION 
     Many prior art hypodermic syringes have a retractable needle. The needle is manually retrieved by the forward end of the plunger after a shot has been administered. The retraction of the plunger into the barrel pulls the needle into the body of the syringe. This manipulation of the hypodermic syringe requires both hands and it is possible that the hand holding the outer barrel could come in contact with the needle before it is fully retracted. 
     This invention relates to hypodermic syringes which have a barrel with a needle mounted on the forward end and a plunger inserted into the rear end. After the syringe has been used, the exposed needle is contaminated and must be disposed of in such a manner as to prevent inadvertent needles sticks. This invention automatically withdraws the contaminated needle into the syringe at the completion of the plunger stroke. 
     DESCRIPTION OF THE PRIOR ART 
     Acquired Immune Deficiency Syndrome(AIDS) has increased the danger from being inadvertently stuck by a used syringe needle. It is recognized that even a minute transfer of bodily fluid from a person infected with a disease, such as AIDS, into another person&#39;s blood stream can transmit the disease. The danger is not confined to the medical community though a great majority of inadvertent needle sticks have been recorded by medical personnel. However, the increasing number of self administered drugs, both legal and illegal, pose a threat to the general population. Also, the well publicized lack of proper procedures for disposal of medical waste has also exposed the general population to contaminated needles. 
     Since it has been demonstrated that innocent people can be infected with such diseases as AIDS, through inadvertent needle sticks, many devices have been designed to eliminate or reduce this risk. One approach to reducing the risk involves drawing the hypodermic needle, in some manner, into the empty syringe so that the sharp end is no longer exposed. Examples of this approach are shown by U.S. Pat. No. 5,092,853, Couvertier, U.S. Pat. No. 5,681,292, to Tober, et al and U.S. Pat. No. 5,984,898 to Garvin. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a hypo dermic syringe and needle that requires only one hand for operation. After the shot is completed, the same hand holding the hypodermic syringe merely increases the pressure on the plunger thereby initiating automatic retraction of the needle into the syringe. 
     Another object of the invention is to provide a collet which expands and releases a spring biased needle retractor in response to the forward movement of the plunger. The forward end of the outer barrel carries a wedge which insures the collet fingers will spread apart upon forward movement of the collet. 
     It is another object of the present invention to provide a vent in the plunger. The vent allows air to escape from the interior of the plunger as the needle assembly is retracted by or in response to spring action. 
     Other objectives and advantages of this invention will become apparent from the following description taken in conjunction with the accompanying drawings wherein are set forth, by way of illustration and example, certain embodiments of this invention. The drawings constitute a part of this specification and include exemplary embodiments of the present invention and illustrate various objects and features thereof. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a partial sectional view of the syringe; 
     FIG. 2 is a partial sectional side view of a syringe shown with the plunger in the forward position, a screw mounted needle according to the present invention is also shown; 
     FIG. 3 is a partial sectional side view of a combination syringe and needle according to the present invention shown in the retracted position; 
     FIG. 4 is an exploded view of a syringe according to the present invention showing the assembly sequence of the component parts with the forward end of the barrel enlarged; 
     FIG. 5 is an enlarged partial sectional view of the forward end of the assemble syringe according to the present invention; 
     FIG. 6 is a planned view of the needle retractor of the present invention; 
     FIG. 7 is the sectional view of the needle retractor shown in FIG. 6; 
     FIG. 8 is an end view of the expanding collet used in the present invention; 
     FIG. 9 is a plan view of the collet; 
     FIG. 10 is a cross-sectional view of the collet shown in FIG. 8 along section line  9 — 9 ; 
     FIG. 11 shows an alternative sealed arrangement of the needle retractor wherein the O-ring type seals have been replaced with static seals. 
    
    
     DETAILED DESCRIPTION 
     As shown in FIGS. 1-5, the invention is a combination syringe  20  and needle  10 . The device features a separately attachable needle hub including a metal cannula  12  and a threaded attachment portion  14 . These parts are adaptable to utilize a needle assembly which can be utilized on a conventional syringe with a female “Luer Lok” component. For smaller syringes, the needles are permanently attached to the syringe. 
     The syringe  20  includes a hollow inner barrel  60  which cooperates with a needle retractor  30  to draw the needle  10  into the inner barrel following use of the needle. This action is accomplished by continuing the stroke of the syringe plunger  40  following the emptying of the syringe. The continued stroke of the plunger  40  moves collet  66  forward and releases needle retractor  30  which is then propelled by spring action into the body of the inner barrel. 
     The syringe  20  is made up of an outer barrel or tube  50  and an inner barrel  60 . The inner barrel has a forward end  64  which has an additional seal element  62 , O-ring in this embodiment, which seals the inner barrel to the inner surface of the outer barrel  50 . This creates a fluid containment chamber which can be pressurized by the introduction of the plunger  40  into the containment chamber from the rear end of the syringe. The plunger has a tubular body  40  and an annular plunger end  44  on a forward end of the plunger. At the rear end of the plunger a push element  46  can be provided to engage the user&#39;s thumb. A vent  71  is formed in the rear end of the plunger adjacent to push element  46 . The vent  71  permits outward flow of air from the interior of the plunger when the needle  10  and retractor  30  are retracted into the plunger. 
     The forward end  64  of the inner barrel  60  also includes a collet  66  which includes slots  67 . The collet has a slotted external funnel shape which creates a contracting and clamping effect for the collet as it is withdrawn through the opening  72  located at the forward end of the outer tube  50 . The collet is biased into a clamping or retracted position by a short spring  68  which biases the inner barrel  60  rearwardly with respect to the outer tube  50 . 
     The device further includes a retracting needle holder  30  shown in detail in FIGS. 6 and 7. The holder  30  is adapted to be inserted through the tubular body of the inner barrel  60  from a rearward end thereof. The retracting holder  30  includes a body portion  32  with an end cap  34  on the rearward end thereof and a fluid port  36  located along a mid-section of the holder and extending to the forward end thereof. The retracting holder  30  passes fluid from the containment chamber upon pressurization thereof by the plunger  40  through the fluid port  65  of the inner barrel  60  through the holder fluid port  36  into the needle  10 . The holder is sealed to the inner surface of the inner barrel  60  by two seals  33  and  35 . In the first embodiment shown in FIG. 17, the seals  33  and  35  are O-ring type seals. These are termed dynamic seals. An alternative embodiment of the sealing arrangement between the holder  30  and the inner barrel  60  is shown in FIG. 11 wherein static annular pressure seals  33 A and  35 A are used between the exterior annular edge of the holder  30  and the interior annular diameter restrictions of the inner barrel  60 . 
     Details of the collet  66  of this embodiment are shown in FIGS. 8,  9  and  10 . The collet includes a plurality of slots  67  which allow for expansion and contraction of the collet as the exterior funnel shape of the collet is urged forwardly and rearwardly through the forward opening  72  in outer tube  50  of the syringe  20 . The slots  67  are larger at the forward ends  73  of the collet and taper rearwardly. The forward ends  73  of the slots  67  are sized to accommodate the wedges  74 . When the collet  66  is urged rearwardly with respect to the outer tube  50  by a short spring  68 , the slots  67  in the collet forward end are forced into a closed position, without interference from wedges  74 , reducing the diameter of the collet and clamping the holder  30 . This clamping and retention of the holder is helped by the trapped edge  31  which is present of the exterior of the holder  30 . The collet  66  clamps onto the holder just behind the trapped edge. The trapped edge  31  is shown as an annular element in this embodiment, however, it can take on any shape which binds against the restricting edges of the collet  66  and retains the holder  30  in the forward end of the inner barrel  60 . 
     The retracting holder  30  is biased rearwardly by long spring  38  which pushes on the end cap  34  of the holder. To release the holder  30 , the collet  66  is expanded by forward movement of the collet  66  in response to contact with the inner barrel forward end  64 , and the forward end  44  of the plunger. The forward movement of the collet  66  frees the collet from the constriction of the opening  72  and engages the narrowed portions  75  of the slots  67  with the wedges  74  to force the collet to expand clear of the lip on the retracting holder  30 . 
     When a user has dispensed the fluid by a full stroke of the plunger, the plunger is pushed past the full stroke position and the plunger end  44  urges against the inner barrel  64  which in turn pushes the collet  66  forward. By pushing forward, the collet  66  expands and the holder  30  disengages from the collet  66  and the holder  30  is propelled rearwardly into the tubular body of the inner barrel  60 . The syringe  20  and the needle  10  are then disabled with the needle trapped within the syringe as shown in FIG.  3 . 
     The assembly sequence of the present invention is shown in FIG. 4 the plunger  40  and the forward end  44  are assembled. The holder  30  and the associated long spring  38  and the seals  33  and  35  are then inserted into the inner barrel  60  which is comprised of a forward end  64  and seal  62  and collet  66 . The inner barrel and the short spring  68  are loaded into the outer tube  50  followed by the insertion of the assembled holder  30 . The holder is inserted until engagement of the collet occurs forward followed by the insertion of the assembled plunger. The entire syringe includes four polymer plastic molded parts, namely the plunger, outer and inner barrels, the holder, and three seals, and two springs. The seals can also be a polymer and consequently be molded together with the respective inner barrel and holder as desired. By virtue of the comparatively few numbers of parts and their simplicity in execution, the present syringe and retractable needle combination can be readily and economically manufactured. 
     It is to be understood that while I have illustrated and described certain forms of my invention, it is not to be limited to the specific forms or arrangement of parts herein described and shown. It will be apparent to those skilled in the art that various changes may be made without departing from he scope of the invention and the invention is not to be considered limited to what is shown in the drawings and described in the specification.