Abstract:
A safety needle cannula module that is interchangeable in combination with a safety syringe and plunger module, wherein the safety needle cannula module is formed with one of a variety of needle cannula sizes and wherein a safety syringe may be one of a variety of syringe sizes. The safety needle cannula module with needle cannula of desired size is attached to a safety syringe module wherein said safety syringe module is a desired size. After medication is injected into a body with the safety needle cannula and the safety syringe, the safety syringe module reacts with the safety needle cannula module and further causes said safety needle cannula to automatically retract and be disposed within the hollow plunger within said safety syringe module.

Description:
This application is a continuation-in-part of U.S. patent application Ser. No. 09/453,393 filed on Dec. 3, 1999 now U.S. Pat. No. 6,099,500. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a single use syringe for injecting medicine into a patient. More particularly, the invention relates to a safety syringe having a retractable needle cannula that renders the needle cannula harmless after it is used. 
     2. Background of the Related Art 
     Many communicable diseases can be spread through the penetration or scratching of the skin by a needle that was previously used by another having a disease. Spreading of the disease in this manner may occur by accident, such as with medical personnel making injections, or it may occur through misuse, such as by intravenous drug users using a previously used needle cannula. 
     Various syringes have been invented, designed and developed to retract the needle into the syringe or the plunger inside of the syringe. Some of these devices are U.S. Pat. No. 4,973,316 (Dysarz), U.S. Pat. No. 4,978,343 (Dysarz), U.S. Pat. No. 5,180,369 (Dysarz), U.S. Pat. No. 5,267,961 (Shaw), U.S. Pat. No. 5,019,044 (Tsao), U.S. Pat. No. 5,084,018 (Tsao), U.S. Pat. No. 5,385,551 (Shaw), U.S. Pat. No. 5,389,076 (Shaw), U.S. Pat. No. 5,201,710 (Caselli), U.S. Pat. No. 5,407,436 (Toft et al), U.S. Pat. No. 5,769,822 (McGary et al), and U.S. Pat. No. 6,010,486 (Carter et al) . These designs have needles which retract at the end of the injection. Most of these designs have not reached the market due, at least in part, to problems associated with expense of manufacturing, poor reliability or user acceptability. However, even though some of these designs operate poorly are costly, they have still been commercialised due to the great need in hospitals or clinics for any type of safety syringe. 
     Most of the existing safety syringe designs allow for automatic retraction of the needle cannula into the plunger barrel of the syringe when the plunger is fully extended into the syringe. The automatic retraction is triggered when the plunger makes physical contact with the distal end of the syringe barrel. Typically, the end of the plunger is provided with a disengageable or sacrificial member at the distal end and the needle cannula is secured by a disengageable or sacrificial member. When the plunger reaches the fully extended position, the physical contact between the plunger and the needle cannula causes activation of the two respective disengageable or sacrificial members. In this manner, the end of the plunger barrel is opened and presented to receive the needle cannula. The needle cannula, no longer secured in position, is biased into the plunger barrel by a spring. 
     Conventional syringes are typically available in modular systems or kits in which approximately ten different sizes of syringes and approximately ten different sizes of needle cannulas can be used interchangeably. This allows an inventory of twenty items to be used in approximately 100 different combinations in accordance with the present need. However, the safety syringes presently available and described in the above patents are not modular and require stocking of an integral safety syringes for each combination of syringe size and needle cannula size desired, for example 100 different safety syringes. Particularly, in light of the greater cost these syringes, the cost, distribution and storage of safety syringes is much greater than conventional syringes. 
     Despite the prevalence of modular convention syringes, the emergence of a multitude of safety syringe designs and the increasing public outcry for safety syringes, the complexities of the safety syringe mechanisms have limited the number of attempts to design a safety syringe that is modular. Two such attempts include modular syringe tip designs that are combined with a conventional syringe as described in U.S. Pat. No. 5,891,093 (Dysarz) and U.S. Pat. No. 5,935,113 (Dysarz). Compared with the foregoing automatically retracting safety syringes, these two designs can be considered to have safety needle cannula assemblies that are self-contained and manually operated, while being connectable to a conventional syringe and with a conventional locking arrangement. While these devices serve the aforementioned need for modularity, the obvious drawbacks to the devices include the manual retraction mechanism and the additional length that the needle cannula assembly adds to the syringe. 
     Another deign utilises a modified luer-lok that requires pressed fittings, a cutting ring and a fiangible position that are to be activated or actuated at the same time requiring more strength in the hands and fingers of the user which many medical people do not have. Still another problem with this design is that the needle cannula must be pushed and moved in the direction of the distal end of the needle cannula and if the needle cannula is in an artery or a vein at the time, the needle cannula will pierce the other side of the artery or vein and deposit medication into an undesirable area of the body. Still yet another problem with this design is that the plunger tip must enter a restricted area of the luer-lok and restrict and trap the medication still contained in the area of the stopper. And still yet another problem with this design is that when the outer hub is being attached to the luer-lok, the proximal end of the inner hub could be hit by the distal end of the luer-lok fitting and cause the frangible portion to break or otherwise fail. 
     Therefore, there remains a need for a modular safety syringe system or kit that provides a selection of syringe modules having various sizes and a selection of needle cannula modules having various sizes that can be combined on site to form an automatically retractable safety syringe of a desired configuration. It would be desirable if the automatically retractable safety syringe has similar length and usability as a conventional syringe. It would be further desirable if the used automatically retractable safety syringe was compact and secure against accidental needle sticks. 
     SUMMARY OF THE INVENTION 
     The invention provides a kit of components for assembling modular safety syringes. The kit comprises two or more safety syringe modules having different diameters and two or more safety needle cannula modules. Each safety syringe module has a syringe barrel; a safety plunger extending through a proximal end of the syringe barrel, wherein the safety plunger having a plunger barrel, a sliding gasket formed along the perimeter of the plunger barrel near the distal end for the sealing plunger against the interior sidewalls of the syringe barrel, and a rigid member adjacent the sealing member; and a connector formed in the distal end of the syringe barrel. Each of the two or more safety needle cannula modules have a housing having a connector formed at a proximal end of the housing and a cannula passage formed through a distal end of the housing; a needle cannula extending through the cannula passage; a slidable piston flange coupled to the needle cannula; a retaining member securing the slidable piston flange in the proximal end of the housing; and a spring disposed within the housing to bias the slidable piston flange in the direction of the plunger opening from the distal end towards the proximal end. The connectors in the two or more safety syringe modules are sealably securable to the connectors in the two or more safety needle cannula modules. Accordingly, securing any one of the two or more safety syringe modules provides alignment of the rigid member of the plunger with the retraining member of the safety needle cannula module and alignment of the slidable piston flange with the sealing member of the plunger. 
     Preferably, the rigid member of the plunger is an end ridge, probably slopped. The retaining element is selected from a shear plate, break plate, a friction ring, a sacrificial membrane, or a snap on ring. Where the retaining element is a shear plate or a break plate, it may optionally include first and second concentric notches formed therein, preferably such that the rigid member is aligned to contact the retaining element between the first and second concentric notches. Similarly, the sealing member is selected form a break plate, a friction plug, a sacrificial membrane, a snap on plug. The connectors are selected from threads, luer-loks, or snap-on fittings. 
     Another aspect of the invention provides an improvement to a medical device having an elongated hollow body; a moveable hollow member slidable axially in the body; a retraction mechanism including a needle extending from the body for injecting of collection fluid, a needle holding member having an unretractable position, a spring for applying retraction force to the needle holding member in a retraction direction, and a retaining element capable of holding the needle holding member against the retraction force provided by the spring; and a cap releasably sealing a passage in the end of the moveable hollow member that is positioned within the body; the retaining element being triggered to retaining the needle holding member for retraction of the needle in response to selective movement of the moveable member, and the cap being retained from the passage of the movable hollow member in response to the selective movement of the hollow member. The movement omprises a sloping end ridge formed on the end of the moveable hollow member to contact the retaining element upon selective movement of the moveable member. For example the retaining element may be selected from a break plate, a friction ring, a sacrificial membrane, or an interference fit and may be triggered by failing, sliding, or disengaging. Particularly, the retaining element or cap may be sloped along the sloping end ridge. 
     Yet another aspect of the invention provides an improvement to a medical device having an elongated hollow body; a movable hollow member slidable axially in the body; a retraction mechanism including a needle extending from the body for injecting or collecting fluid, a needle holding member having an unretracted position, a spring for applying retraction force to the needle holding member having an unretracted position, a spring for applying retraction force to the needle holding member in a retraction holding member in a retraction direction, and a retaining element capable of holding the needle holding member against the retraction force provided by the spring; and a cap releasably sealing a passage in the end of the moveable hollow member that is positioned within the body; the retaining element being triggered to release the needle holding member for retraction of the needle in response to selective movement of the moveable member, and the cap being released from the passage of the moveable hollow member in response to the selective movement of the moveable member. The improvement comprises a spring shield coupled to the needle holding  10  member and extending around the spring, wherein the spring is disposed concentrically around the needle, where the spring shield has a outer diameter that is less than that of an internal diameter of the passage of the moveable hollow member. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     So that the above recited features and advantages of the present invention can be understood in detail, a more particular description of the invention, briefly summarised above, may be had by reference to the embodiments thereof which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments. 
     FIG. 1 is a section elevation view of the safety needle cannula module fixed to the distal end of the safety syringe and plunger module. 
     FIG. 2 is an enlarged section elevation of the safety needle cannula module shown fixed to the safety syringe module. 
     FIG. 2A is an enlarged section elevation showing an  0  ring seal. 
     FIG. 3 is a section plan view of the needle cannula module as taken through FIG.  1 . 
     FIG. 4 is a section plan view of the pop out dome in the distal end of the plunger module as taken through FIG.  1 . 
     FIG. 5 is an enlarged section elevation of the distal end of the plunger module. 
     FIG. 6 is an enlarged section elevation of the plunger module moving toward the safety needle cannula module. 
     FIG. 7 is an enlarged section elevation of the safety needle cannula module compressing the pop out dome. 
     FIG. 8 is a section elevation of the safety needle cannula module popping out the pop out dome. 
     FIG. 9 is a section elevation of the safety needle cannula module thrusting into the plunger module. 
     FIG. 10 is a section elevation of the safety needle cannula inside of the plunger module. 
     FIG. 11 is an enlarged section elevation of the pop out dome in the plunger module. 
     FIG. 12 is an enlarged section elevation of the pop out dome as it would be compressed or pushed in. 
     FIG. 12A is a section elevation of the outer periphery of the pop out dome. 
     FIG. 12B is a section elevation of the pop out dome rotating. 
     FIG. 12C is a section elevation of the pop out dome being popped out. 
     FIG. 13 is a section elevation of the pop out dome in an inverted position. 
     FIG. 14 is a section elevation of the pop out dome falling into the plunger module. 
     FIG. 15 is a section elevation of the second preferred embodiment of the snap on safety needle module and the pop out plunger plug. 
     FIG. 16 is an enlarged section elevation of the snap on safety needle cannula module and the pop out safety plunger plug. 
     FIG. 17 is a section plan view of the needle and base plate. 
     FIG. 18 is a section plan view of the pop out safety plunger plug inside the plunger. 
     FIG. 19 is an enlarged section elevation view of the snap on device. 
     FIG. 20 is an elevation view of the snap on needle cannula module. 
     FIG. 21 is an enlarged section elevation view of the plunger plug moving toward the needle cannula. 
     FIG. 22 is an enlarged section elevation view of the plunger module thrusting into the safety needle cannula module. 
     FIG. 23 is an enlarged section view of snap on safety needle cannula module and the needle cannula popping into the plunger module. 
     FIG. 24 is a view of the snap on safety needle cannula module with the needle cannula inside of the plunger module. 
     FIG. 25 is a section elevation of the preferred embodiment. 
     FIG. 26 is an enlarged section elevation of the third preferred embodiment. 
     FIG. 27 is a section plan view as taken through FIG.  25 . 
     FIG. 28 is a section plan view as taken through FIG.  25 . 
     FIG. 29 is an enlarged section elevation as taken through from FIG.  26 . 
     FIG. 30 is an enlarged elevation of the device in operation. 
     FIG. 31 is a section elevation of the device moving. 
     FIG. 32 is a section elevation of the device being broken down. 
     FIG. 33 is a section elevation showing the needle cannula in the syringe and plunger. 
     FIG. 34 is a section elevation of the device of the third preferred embodiment. 
     FIG. 35 is a section plan view taken through FIG.  34 . 
     FIG. 36 is a section plan view taken through FIG.  34 . 
     FIG. 37 is a section plan view taken through FIG.  34 . 
     FIG. 38 is a section plan view taken through FIG.  34 . 
     FIG. 39 is a plan view of the tab ring. 
     FIG. 40 is a section elevation of the tab ring as taken through 
     FIG.  39 . 
     FIG. 41 is a plan view of the support flange. 
     FIG. 42 is a section plan view of the module flange. 
     FIG. 43 is a section plan view of the support flange. 
     FIG. 44 is a section plan view of the barrier assembly. 
     FIG. 45 is a section plan view of barrier assembly rotated. 
     FIG. 46 is an elongated section elevation of the modularised safety syringe as taken through FIG.  34 . 
     FIG. 47 is a section elevation of the plunger being thrust into the needle cannula module. 
     FIG. 48 is a section elevation of the device being broken apart. 
     FIG. 49 is a section elevation of the needle cannula inside the plunger and syringe module. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The present invention provides a modular safety syringe system or kit that provides a selection of safety syringe modules having various sizes and a selection of needle cannula  8  modules having various sizes that can be combined on site to form an automatically retractable safety syringe of a desired configuration. In addition to requiring a common interface between a safety syringe module and a needle cannula module, as with conventional modular systems, the present invention also requires and facilitates a specific co-operation relationship between the syringe plunger module and the needle cannula module. 
     Each safety syringe module of the present invention includes a single barrel, a safety plunger extending through a proximal end of the syringe barrel, and a connector formed in the distal end of the syringe barrel. A syringe barrel may be of any length and diameter, as dictated by the volume of fluid to be delivered, through the syringe, and will include a connector have a fixed diameter. In systems, sets or kits having a plurality of syringes with different diameters, each syringe should have a connector with a common diameter and a common connection type. For example, three syringe barrels may be provided with diameters 2, 2.5, and 3 centimeters, respectively, but each of the three syringe barrels should have a connector of the same type, such as threads, and of the same diameter, such as 1.5 centimeters. It should be recognised that sets having syringes with wide variations in single barrel diameter, the set may include a first subset of syringes having a first common connector with a first common diameter and a second subset of syringes having a second common connector with a second common diameter. The present invention contemplates any number of subsets, each subset having the same or different type of connector, and each subset having the same or different connector diameter. It should be recognised that the term “diameter” as used herein shall not be limited to the dimensions of a circular opening, but shall include the dimensions of any shape of the opening, for example shapes like squares, triangles, ovals and rectangles. 
     The safety plungers of the present invention have suitable lengths and diameters to work in a co-operative relationship inside the syringe barrel. It is anticipated that each syringe of a different diameter will have a corresponding safety plunger of suitable size. The safety plunger has a plunger barrel, a sliding gasket formed along the perimeter of the plunger barrel near the distal end for sealing the plunger against the interior side walls of the syringe barrel, and a removable member sealing a central opening in the distal end of the plunger barrel. The safety plunger will also include a lip or smaller structure that engages a critical portion of the needle cannula module as described below. 
     The safety needle module has a connector that is designed to be coupled to the connector on the safety syringe module. The connectors may be of various types, including but not limited to male/female threads, snap on, and luer-lok tips. In systems, sets or kits having a plurality of safety needle modules with different cannula diameters, gauges, types or lengths, each safety needle module should have a connector with a common diameter and a common connection type. For example, three safety needle modules may be provided with, but not limited to, 16G, 20G, and 30G cannulas, respectively, but each of the three modules should have a connector of the same type, such as male threads, and of the same diameter, such as 1.5 centimeters. Furthermore, it should be recognised that the safety needle modules will preferably all have the same type of connector, such as male threads or the male portion of the luer-lok, and the safety syringe modules will preferably all have the same type of connector that mates the needle module connector, such as female threads of the female portion of the luer-lok. In the case where there are subsets of syringes having connectors with different diameters, then there will also be subsets of safety needle modules having connectors with the same mating diameters. 
     The safety needle cannula includes a housing having the connector at the proximal end and a cannula passage through the distal end. A needle cannula coupled to a slidable position flange extends through the cannula passage. The slidable position flange is secured to the housing by a disengageable, sacrificial or retaining member. A spring is disposed within the housing to bias the slidable piston flange, and consequently the needle cannula, away from the distal end towards the proximal end. The spring surrounds the needle cannula and is maintained in a biased or spring loaded condition between the distal end of the housing and the slidable piston flange. It is important that the spring provide sufficient force to move the needle cannula into the plunger barrel upon release, but the spring should not be so strong as to fatigue or cause failure to the housing. 
     It should be recognised that the disengageable or sacrificial members in the safety plunger and the safety needle module may take many forms, including plates that can fail, break or shatter as described in U.S. Pat. No. 5,180,369 (Dysarz) incorporated by reference herein, frictionally engaged retaining rings and plugs as described in U.S. Pat. No. 5,285,551 incorporated by reference herein, sacrificial membranes, interference fits, and the like. 
     It is a critical aspect of the invention that a rigid component of the safety plunger is disposed at an appropriate position to engage and actuate the retaining member in the safety needle module and that a rigid component of the safety needle module is disposed at an appropriate position to engage and actuate the sealing member in the safety plunger. Since syringes typically have cylindrical barrels, although they could just as well have any shaped cross-section, the positions of the two rigid components, the sealing member and the retaining member can be described in terms of concentric members having a specific radial distance from the axial centerline of the needle cannula. While tow of the concentric members are in the safety plunger and the two other concentric members are in the needle module, the members must achieve a standard, fixed or consistent co-operative relationship when assembled and, consequently, must have standard radii or other dimension and threads specified for each of the two rigid components, the sealing member and the retaining member. For any given set or subset of safety syringe modules and safety needle modules, the radii musts be the same regardless of the syringe diameter or the cannula gauge. In other words, the size and alignment of the members accounting for the automatic retraction must be consistent in order for the retraction to occur. 
     Consistent alignment of the members, including alignment of a rigid plunger member with the needle retaining member and alignment of the rigid safety needle member with the plunger sealing member, can be achieved either by (a) using a constant plunger barrel diameter regardless of syringe diameter, or (b) using plunger barrels having a diameter just smaller than the syringe barrel, but having a diameter at the distal end that is reduced, or perhaps even increased, to form or achieve the fixed radii of the rigid plunger component. The former option is less desirable, because the plunger barrel could wobble from side to side and the gasket member would not receive as much physical support. 
     Now referring to the Figures, FIG. 1 is a section elevation view of the system or kit of the first preferred embodiment of the present invention. The system includes a separate safety syringe module and a safety needle cannula module  3 . The safety syringe module includes a safety plunger  1  and a syringe module  2 . A syringe connector  6  is shown formed in the distal end of the syringe module  2 , preferably forming a set of female threads. The syringe module  2  is a hollow elongated barrel with an inside surface and an outside surface. The safety plunger is shown disposed within the syringe barrel  2  with a thumb flat  5  shown at the proximal end of the safety plunger. 
     The safety needle cannula module  3  is shown as hollow with an inside surface and an outside surface and with a needle cannula  8  extending form the distal end of a housing  46  having male threads  9  that are attachable to the female threads  4  formed on the syringe connector  6  of the syringe module  2 . The needle cannula  8  is shown extending from the support tunnel  7  shown formed in the distal end of the safety needle cannula module  3 . The spring shield  11  is shown near the cannula flat  12 . The distal end of the biased spring  13  is shown thrusting on the cannula flat  12  and the proximal end of the biased spring is shown thrusting on the needle base plate  14 . The needle base plate  16  is shown disposed on and thrusting on the base plate  14  that is on the proximal end of the spring shield  11 . The base plate flange  17  is shown extending from the base plate. The retaining ring  23  is shown forming a liquid tight seal while retaining the needle cannula in the safety needle cannula module. 
     The distal end of the plunger module is shown with a reduction cone  18  and a dome support means  19 . The dome support means is suitably fixed to the reduction cone at the proximal end of the dome support means and a dome foundation  20  is formed on the inside of the distal end of the dome support means. A pop out dome  21  is shown suitably disposed in the dome foundation that will be seen more clearly in FIG. 2. A sliding plunger gasket  22  is shown formed on the outside surface of the dome support means. 
     FIG. 2 is an enlarged section elevation of the distal end of the syringe module  2  and the safety needle cannula module  3 . 
     The needle cannula  8  is shown disposed in the support tunnel  7  wherein the needle cannula will be suitably supported when thrust into a body and thereby will not deflect. The needle cannula further extends into and is disposed in the biased spring  13  wherein it could be supported laterally by the biased spring and therefor reduce or eliminate any deflection in the area of the biased spring. The biased spring is further supported and protected by the spring shield  11 . The spring shield protects the biased spring  13  as it thrusts the needle cannula into the plunger  1 . 
     The retaining ring  23  is shown forming a fluid tight and gas tight barrier from the modular flange  24  to the base plate flange  17 . The retaining ring also retains the, the spring shield  11  and the biased spring  13  and prevents the biased spring from thrusting the needle cannula  8  into the syringe module  2 . The retaining ring is shown with V notches  25  formed in the inner periphery and the outer periphery of the retaining ring. The configuration of the V notches matches the bevelled configuration of the outside periphery of the base plate flange  17  and beveled configuration of the inner periphery of the modular flange  24  therein forming a gas tight and fluid tight connection. The retaining ring may be made of rubber, plastic, vinyl or any other soft material and the retaining ring may also be made out of hard material such as glass, plastic, or metal by design choice. The retaining ring in this description is designed to deflect to release the biased spring and the needle cannula, however the module flange and the base plate flange could also be made to fail to release the biased spring and needle cannula. There are a number of configurations that the retaining ring may have such as that shown in FIG.  2 A and it should be known that the possible number of configurations is great. All parts of FIGS. 1 through 14 have a distal end and a proximal end. 
     The pop out dome  21  is shown held in place by the dome foundation  20 . The dome foundation  20  is shown more clearly in FIG.  5 . The dome foundation is formed on the distal end of the dome support means  19 . The proximal end of the dome support means is shown suitably fixed to the distal end of the plunger  1 . The dome foundation is formed on the inside surface of the dome support means and the sliding plunger gasket  22  is shown on the outside surface of the dome support means. 
     Referring to FIG. 2A there is shown a retaining ring  15  that is in the configuration of an O ring in section and acts in the same manner as the retaining ring. The base plate flange and the module flange  24  have rounded configurations to accommodate the O retaining ring. 
     Referring to FIG. 3 there is shown a section plan view of the safety needle cannula module  3  and part of the syringe module  2  as taken through FIG.  1 . 
     The retaining ring  23  is shown held in place by the module flange  24  on the outer periphery and the base plate flange  17  on the inner periphery. The needle cannula  8  is shown in the center of the safety needle cannula module  3  and the base plate  14  is shown near needle cannula  8 . 
     Referring to FIG. 4 there is shown a section plan view of the pop out dome  21  as taken through FIG.  1 . 
     The pop out dome is shown supported on the dome foundation  20  that is at the distal end of the dome support means  19 . The sliding plunger gasket  22  is shown between the dome support means and the syringe module  2 . 
     Referring to FIG. 5 there is shown an enlarged section elevation of the dome foundation  20  as then through FIG.  2 . 
     The sliding plunger gasket  22  is shown on the outer periphery of the dome support means  19 . The inside surface of the dome foundation  20  is shown of a lesser diameter than the inside surface of the dome support means  19  to allow the pop out dome  21  to fall out of the dome support means unhindered. A dome notch  26  is shown formed in the dome foundation and the dome notch is circumambient in the dome foundation. The dome flange  27  is shown extending the outer periphery  10  of the pop out dome  21  and is disposed in the dome notch  26  forming a fluid tight seal between the dome notch and the dome flange. The fluid tight seal and the gas tight seal could also be formed with adhesive or a gasket between the dome notch and dome flange. The dome trunnion  28  is shown also formed near the outer periphery of the pop out dome and extends from the distal end of the pop out dome to the proximal end of said pop out dome and will be sown in FIGS. 12A,  12 B, and  12 C as to how the dome trunnion will cause the pop out dome  21  to pop out of the dome foundation. 
     Referring to FIG. 6 there is shown an enlarged section elevation of the safety needle cannula module  3  the syringe module  2  and the plunger  1 . 
     The plunger is moving in a cannula direction  29  to force the pop dome  21  into the base plate  14  and to cause the distal end of the dome support means  19  into the retaining ring  23 . 
     Referring to FIG. 7 there is shown an enlarged section elevation of the plunger  1  being thrust in a cannula direction  29 . 
     The distal end of the dome support means  19  and the dome foundation  20  have made contact with the retaining ring  23  and are thereby thrusting on the retaining ring. The base plate  14  is also applying essentially a concentrated load on the pop out dome plate  21  causing the pop out dome  21  to deflect and further starting the dome flange  27  to rotate about the dome trunnion  28 . 
     Referring to FIG. 8 there is shown an enlarged section elevation of the dome support means  19  and the dome foundation having thrust the retaining ring  23  off the base plate flange  17  and the module flange  24  thus freeing the retaining ring, the base plate  14 , the spring shield  11  thereby allowing the biased spring  13  to thrust the needle cannula  8  into the plunger  1 . The pop out dome  21  has already been popped out of the dome foundation  20  into the inside of the plunger  1 . 
     Referring to FIG. 9 there is an enlarged section elevation of the needle cannula  8  being thrust into the inside of the plunger  1 , 
     The retaining ring  23  is no longer retaining the base plate  14  and spring shield  11  thus allowing the distal end of the biased spring  13  to thrust on the cannula flat  12  and the proximal end of the biased spring to thrust on the needle base plate  16  thus thrusting the needle cannula  8  in a plunger direction  51  into the plunger  1 . 
     Referring to FIG. 10 there is shown a section elevation view of the needle cannula  8  inside of the plunger  1 . 
     The needle cannula  8  cannot fall out of the plunger because it is entangled in the spring  13 . 
     Referring to FIG. 11 there is shown a section elevation of the pop out dome  21  suitably supported in the dome foundation  20  at the distal end of the dome support means  19 . 
     As the plunger  1  and the pop out dome are forcing medication into the needle cannula hence into a body; any hydrostatic pressure  10  cause by the thrust of the plunger is essentially equal on all points of the dome and the pop out dome and the shape of the pop out dome remains unchanged and all forces are essentially evenly distributed through the pop out dome and into the dome foundation. When a concentrated load is applied to parts of the pop out dome, the pop out dome will start to deflect in the area of the applied concentrated load. 
     Referring to FIG. 12 there is shown a section elevation view of the pop out dome  21  as it will look as the base plate  14  exerts a concentrated load on the pop out dome  21 . The pop out dome  21  will start to deflect and as the concentrated load is continued, the pop out dome start to form a reverse dome  30 . 
     Referring to FIG. 12A there is shown another section elevation similar to FIG. 5 showing the dome flange  27  inside of the dome notch  26  that is formed in the dome foundation  20 . 
     As the pop out dome  21  is forced into a reverse dome, the dome flange will start to rotate about the dome trunnion  28  and will further start to withdraw from the dome notch  26 . 
     Referring to section  12 B there is shown an enlarged section elevation of the pop out dome  21  forming into a reverse dome  30 . 
     The dome trunnion  28  has rotated about the proximal end of the dome foundation  20  causing the dome flange  27  to be withdrawn from the dome notch  26  and further causing the dome flange to reverse its configuration wherein it will unable to catch onto or into the dome notch. 
     Referring to FIG. 12C there is shown an enlarged section elevation of the complete reversal of the pop out dome  21 . 
     The dome trunnion  28  has been forced completely past the proximal end of the dome foundation  20  and cannot grasp or even touch the inside wall of the dome support means  19  because the dome support means has a greater inside diameter than the outside diameter of the pop out dome reversed or the reversed dome  30  and a greater outside diameter of the dome trunnion; at this moment, the base plate is thrusting into the pop out dome by the biased spring. 
     Referring to FIG. 13 there is shown a section elevation of the pop out dome  21  formed into a completely reversed dome  30  and in a instant the pop out dome will be thrust away from the distal end of the dome support means  19 . 
     Referring to FIG. 14 there is shown a section elevation of the pop out dome  21  and now the reversed dome being thrust from the dome support means  19 . 
     Referring to FIG. 15 there is shown a section elevation of the second preferred embodiment of the present invention. 
     A snap on needle cannula module  31  is shown suitably fixed to the snap on syringe module  32 . The needle cannula  8  is shown as the same needle cannula in the first preferred embodiment. A biased spring  13  is shown disposed about the needle cannula and the spring shield  11   10  is shown disposed about the biased spring. The needle base plate  16  is shown fixed to the proximal end of the needle cannula and the base plate  14  is shown at the proximal end of the needle base plate. The H retaining ring  33  is shown retaining the base plate and the biased spring  13 . 
     The distal end of the plunger  1  is shown with a plunger flange  36  and the plug support means  37  is shown fixed to the distal end of the plunger flange. The compressible plunger seal  35  is shown with compression chambers  38 . The compressor chambers are designed to allow the compressible plunger seal to compress as will be shown in FIG.  20 . 
     Referring to FIG. 16 there is shown an enlarged section elevation of the second preferred embodiment. 
     The snap on syringe module  32  is shown fastened to the snap on needle cannula module  31  by the snap ring  39 . An O ring  40  is shown forming a fluid tight and gas tight connection between the snap on needle cannula module and the snap on syringe module. The H retaining ring  41  is shown fixed to the module flange  24  and the base plate flange  17  wherein each leg  93  of the H retaining ring laps over each side of the inner periphery of the modular flange  24  and each side of the outer periphery of the base plate flange  17  forming a fluid tight and gas tight connection. 
     The double flange plug  34  is shown forming a fluid tight and gas tight connection between the inner surface of the plug support means  37  and the double flange plug. The upper flange  49  and the lower flange  50  are shown holding the double flange plug to the plunger flange  36 . Although there are two flanges shown in this figure, the upper flange is most necessary and the lower flange could be eliminated. 
     Referring to FIG. 17 there is shown a section plan view of the base plate  14  as taken through FIG.  16 . 
     The base plate  14  is at the center of the snap on needle cannula module  31  however it could be offset also or near one side of the safety syringe  2 . The H retaining ring  41  is shown fixed to the module flange  24  and the base plate flange  17 . 
     Referring to FIG. 18 there is shown a section plan view of the double flange plug  35  as taken through FIG.  15 . 
     The plug support means  37  is shown supporting the double flange plug  34 . The compressible plunger seal  35  is shown on the inside surface of the syringe module  2 . 
     Referring to FIG. 19 there is an enlarged section elevation of the snap on means  42  as taken from FIG.  16 . 
     There can be many versions of snap on means and therefor this patent should not be limited to only this version of a snap on means. 
     The snap on needle cannula module  31  is shown with a module snap on flange  43  that is suitably compressing an O ring  40  to form a fluid tight and gas tight connection. The snap on means  42  operates by placing the module snap on flange  43  into the syringe snap on slot  47 ; the snap over ring  44  is pulled over the pull over flange  45  and rotated until the snap on lock  48  shown in FIG. 20 locks the snap on needle cannula module  31  to the snap on syringe module  32 . 
     Referring to FIG. 20, there is shown an elevation view of the snap on needle cannula module  31  suitably fixed to the snap on syringe module  32  by the snap over ring  44  that is locked in place by the snap on lock  48 . 
     Referring to FIG. 21 there is shown an enlarged section elevation of the distal end of the plug support means  37  moving in a cannula direction  29 . 
     Medication is flowing under pressure from the syringe module  2  into the needle cannula  8  and into a body not shown in this figure. 
     Referring to FIG. 22 there is shown an enlarged section elevation of the distal end of the plug support means  37  impacting the proximal end of the H retaining ring  41  in a cannula direction  29   
     The H retaining ring has been dislodged from the base plate flange  17  and the module flange  24  and is now moving in a cannula direction  29 . The base plate  14  has also started to dislodge the double flange plug  34  from the plunger flange  36  by bending the upper flange  49  on the plunger flange  36 . As the double flange plug is being dislodged. The compressible plunger seal is also being compressed by allowing the compressor chambers  38  to change shape. 
     Referring to FIG. 23 there is shown a section elevation of the double flange plug  34  being dislodged from the plug support means  37  and the plunger flange  36 . 
     The biased spring  13  is now controlling the movement of the base plate  14 , the needle cannula  8  and the needle base plate  16  as the biased spring thrusts the needle cannula in a plunger direction  51 . The spring shield  11  is preventing the biased spring from getting caught in the H retaining ring  41 . 
     Referring to FIG. 24 there is shown a section elevation of a disarmed syringe. 
     The needle cannula  8  is in the hollow plunger  1  and the spring  13  will prevent the needle cannula from re-entering the support tunnel  7 . 
     Referring to FIG. 25 there is shown a section elevation of the third preferred embodiment of the present invention. 
     The safety needle cannula module  3  is shown suitably fixed to the syringe module  2 . The needle cannula  8  is shown disposed in the support tunnel  7  and the biased spring  13 . The biased spring is shown disposed in the spring shield  11 . The friction ring  52  is shown held by friction, adhesive or other bonding means to the base plate flange  17  and the module flange  24 . 
     The plunger barrier  53  is shown suitably fixed to the inside surface of the barrier support  54 . 
     Referring to FIG. 26 there is shown an enlarged section elevation of the safety needle cannula module  3 , the distal end of the syringe module  2  and the plunger  1  as taken through FIG.  25 . 
     The friction ring  52  is shown suitably disposed between the base plate flange  17  and the module flange  24  and is held in place by friction only; adhesive or other holding means could be used by design choice. 
     The plunger barrier  53  is shown held to the distal end of the barrier support  54  by a barrier foundation  55 . The sliding plunger gasket  56  is shown suitably fixed to the outside surface of the barrier support. 
     Referring to FIG. 27 there is shown a section plan view as taken through FIG.  25 . 
     The syringe Module  2  is shown fixed to the safety needle cannula module  3  by threads or other suitable means. The outer diameter of the friction ring  52  is shown fixed to the inside diameter of the module flange  24 . The inside diameter of the friction ring  52  is fixed to the outside diameter of the base plate flange  17 . 
     Referring to FIG. 28 there is shown a section plan view of the distal end of the barrier support as taken through FIG.  25 . 
     The syringe module  2  is shown on the outside diameter and the sliding plunger gasket  56 . The distal end of the barrier foundation  55  is shown supporting plunger barrier  53 . 
     Referring to FIG. 29 there is shown an enlarged section elevation of the barrier foundation  55  supporting the plunger barrier  53  as taken from FIG.  26 . 
     The barrier foundation  55  is shown with a barrier notch  57  that supports the barrier flange  58 . 
     Referring to FIG. 30 there is shown an enlarged section elevation of the plunger  1  moving in a cannula direction  29 . 
     The distal end of the sliding plunger gasket  56  is now in contact with the proximal end of the syringe module  2 . The distal end of the barrier foundation  55  is in contact and alignment with the proximal end of the friction ring  52  and the proximal end of the base plate  14  is in engagement with the distal end of the plunger barrier  53 . 
     Referring to FIG. 31 There is shown a section elevation of the distal end of the barrier foundation  55  and the barrier support moving in a cannula direction  29  wherein the barrier foundation and the barrier support  54  have popped the friction ring  52  off of the base plate flange  17  and the module flange  24 . The base plate  14  has also popped the plunger barrier  53  from the barrier notch  57  in the barrier foundation  55 . The biased spring  13  is now thrusting the needle cannula  8  and the plunger barrier into the plunger  1  in a plunger direction  51 . The sliding plunger gasket  56  is shown having slid down the outer surface of the barrier support. 
     Referring to FIG. 32 there is shown a section elevation of the biased spring  13  thrusting the plunger barrier  53 , the base plate  14 , the needle base plate  16 , and the needle cannula  8  into the plunger  1  in a plunger direction  51 . 
     Referring to FIG. 33 there is shown a section elevation of the syringe module  2 , the plunger  1 , and the spring  13  having thrust the needle cannula  8  into the inside of the plunger  1  wherein the needle cannula is trapped and cannot accidentally prick or otherwise injure another. 
     Referring to FIG. 34 there is shown a section elevation of the modularised safety syringe of the fourth preferred embodiment. 
     The modularised safety syringe  59  is shown with a needle cannula  8 , a plunger  1 , a syringe module  2 , a biased spring  13 , a barrier assembly module  61 , a pop out plunger plug  60  in the barrier support  54  and a plug stop  62 . 
     Referring to FIG. 35 there is shown an enlarged section elevation of the modularised safety syringe as taken through from FIG.  34 . 
     The cannula  66  is shown disposed in the support tunnel  7  and having a cone flange  64  at the proximal end. 
     Referring to FIG. 35 there is shown a section plan view of the syringe module  2 , the safety needle cannula module  3  and the barrier assembly module  61 . 
     The cannula  66  is shown in the center of the barrier assembly module and cone flange  64 . 
     Referring to FIG. 36 there is shown a section plan view of the barrier support  54 , the sliding plunger gasket  56  and the pop out plunger plug  60  as taken through FIG.  34 . 
     The sliding plunger gasket is on the inside surface of the plunger  1 . 
     Referring to FIG. 37 there is shown a section elevation of the proximal end of the pop out plunger plug  60  being held in place by the plug stop  62  as taken through FIG.  34 . 
     The plug stop  62  is held in place by the break away tabs  67  that are suitably fixed to the distal plate  68  at the distal end of the plunger  1 . The plunger  1  is shown in the inside surface of the syringe module  2 . 
     Referring to FIG. 38 there is shown a section elevation plan view of the barrier assembly module  61  in the safety needle cannula module  3  and the syringe extension  69 . 
     The barrier assembly is held in place or is fixed to the safety needle cannula module  3  on the module flange  70  that is formed on the inside and proximal end of the safety needle cannula module. The barrier assembly is held in place and is supported by the inner tabs  72  latching onto the module flange  70  and the outer tabs  72  locking onto the support flange  73 . The support flange is formed at the proximal end of the spring shield  11 . The needle cannula  8  is shown in the center. 
     Referring to FIG. 39 there is shown a plan view of the tab ring  74 . 
     The tab ring has a ring flange  75  on the outer periphery and a tab support ring  76  with outer tabs  71  on the inside of the tab support ring. Inner tabs  72  are shown fixed to the inside surface of the tab support ring. A frangible ring  77  is also shown fixed to the inside diameter of the tab ring. Although four inner tabs and four outer tabs are shown there could be as few as one inner tab and one outer tab by design choice or there could also be more than four inner tabs or four outer tabs by design choice. 
     Referring to FIG. 40 there is shown a section elevation of the tab ring  74  as taken through FIG.  39 . 
     The ring flange  75  is shown formed on the tab support ring  76 . The inner tabs  72  are shown formed on the inside surface of the tab ring and the outer tabs  71  are shown formed on the outside surface of the tab ring. The frangible ring  77  is shown suitably fixed to the tab ring  74  by adhesive, friction, or other bonding means by design choice. The frangible ring is designed to break under various design loading or specific concentrated loads by design choice. The ring flange  75  is shown forming the outer periphery of the tab ring. 
     Referring to FIG. 41 there is shown a plan view of the support flange  73 . 
     The support flange is shown with support flange slots  78  formed on the outer periphery of the support flange. The support  10  flange slots are located to correspond with the inner tabs of the tab ring. The spring shield  11  is shown fixed to the support flange and the needle cannula  8  is shown at the center of the support flange. 
     Referring to FIG. 42 there is shown a section plan view of the module flange  70  of the safety needle cannula module  3  that is in the syringe extension  69 . 
     The module slots  79  are formed in the module flange  70  to correspond with the location of the inner tabs formed on the tab ring. 
     Referring to FIG. 43 there is shown a section plan view of the support flange  73  inside of the module flange  70 . 
     The support flange slots  78  are shown in alignment with the module slots  79 . Although the support flange slots  78  are shown in alignment with the module slots in this view, this condition is not necessary so long as the slota are in alignment with the inner tabs and outer tab ring. 
     The safety needle cannula module  3  is shown near the outside and the needle cannula hole  80  is shown on the inside. An annulus  81  is shown formed between the module flange  70  and the support flange  73 . 
     Referring to FIG. 44 there is shown a section plan view of the barrier assembly module  61  being assembled to the safety needle cannula module  3 . 
     The tab ring  74  has been inserted into the annulus  81  formed between the module flange  70  and the support flange  73 . The inner tabs  72  are in the support flange slots  78  and the outer tabs  71  are in the module slots  79  and the inner tabs and outer tabs are pushed through the flange slots and the module slots. 
     Referring to FIG. 45 there is shown a section plan view of the barrier assembly module  61  being fixed to the module flange  70  of the  5  safety needle cannula module  3 . 
     As shown in FIG. 44 the tabs have been inserted in the slots and now the tab support ring  76  has been rotated  82  where in the support flange  73  is locked between the inner tabs  72  and the frangible ring  77  and the module flange  70  is locked between the outer tabs  71  and the ring flange  75  thereby forming a fluid tight and gas tight connection between the safety needle cannula module  3  and the barrier assembly module  61 . The various flanges have covered the slots thereby making the areas around the slot fluid tight and gas tight. Adhesive or other holding means may be applied to this area also. 
     Referring to FIG. 46 there is shown an elongated section elevation of the modularised safety syringe as taken through FIG.  34 . 
     The needle cannula  8  is shown disposed in the support tunnel  7 . A cone flange  64  is shown fixed to the proximal end of the needle cannula  8 . The distal end of the biased spring  13  is thrusting on the cannula flat  12  and the proximal end of the biased spring is shown thrusting on the distal end if the spring foundation  65 . The barrier module  61  is restraining the biased spring from thrusting the needle cannula into the syringe module  2  or plunger  1 . 
     The pop out plunger plug  60  is shown supported laterally and some axially. The stop hooks  63  are holding the plug stop  62  to further prevent the pop out plunger plug  60  from popping out under pressure. The plunger  1  is shown inside of the syringe module  2 . The barrier support  54  is shown in alignment with the frangible ring  77 . The barrier support  54  is shown with a slop  84  at the distal end to place a concentrated load on the frangible ring  77 . 
     Referring to FIG. 47 there is shown an elongated section elevation of the plunger being thrust in a distal direction  38 . 
     The distal end of the barrier support  54  has come in contact with the frangible ring  77  and exerted a concentrated load or point load on the frangible ring  77 . The frangible ring  77  has broken and the frangible plate no longer restrains the thrust of the biased spring  13  and the biased spring is now thrusting on the spring foundation  65 , needle cannula  8 , and the cone flange  64 . 
     As the cone flange is released it is thrust into the pop out plunger plug  61  and a load is further exerted on the pop out plunger plug, as the plunger is thrust into a distal direction  83 . The pop out plunger plug is now exerting a load on the plug stop  62  and the stop hook  63 . 
     Referring to FIG. 48 there is shown a section elevation of the biased spring  13  thrusting the needle cannula  8 , the spring foundation  65  and the cone flange  64  into the pop out plunger plug  60  thereby causing the stop hook  63  to break and thus release the plug stop  62  and the pop out plunger plug from the barrier support  54 . The biased spring continues to thrust the needle cannula into the plunger. 
     Referring to FIG. 49 there is shown a section elevation of the needle cannula  8  inside of the plunger  1 . The spring  13  will remain where it is to prevent the distal end of the needle cannula from re-entering the support tunnel  7  and thereby injuring someone. The distal end of the spring is fixed to the cannula flat  12  and thereby will not let the needle cannula out of the support tunnel.