PATENT DOCUMENT

Abstract:
An injection device including a barrel, a hollow plunger having a portion structured and arranged to move within the barrel, a needle unit, and a safety system that one of automatically causes the needle unit to retract into the plunger when the plunger reaches a substantially fully depressed position. This Abstract is not intended to define the invention disclosed in the specification, nor intended to limit the scope of the invention in any way.

Full Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The instant application is a Continuation-in-part (CIP) application of U.S. application Ser. No. 12/752,186 filed Apr. 1, 2010, which is a US non-provisional application based on U.S. provisional application No. 61/167,741, filed Apr. 8, 2009. The disclosure of each of these applications is hereby expressly incorporated by reference in their entireties. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates generally to syringes, e.g., hypodermic syringes, such are utilized for injection of medicament into the body tissues of human and animal patients. More specifically, this invention relates to a hypodermic syringe having a plunger, piston and needle support structure or needle unit that permits retraction of the needle support and its needle into the plunger of the syringe to prevent the possibility of inadvertent needle pricks and which incorporates a frangible plunger seal that may be broken or separated away to prevent subsequent use or re-use of the syringe. 
     This invention also relates to single-use syringes which automatically retracts a standard interface needle into the syringe when the plunger is substantially fully depressed which is more easily and/or less costly to produce. 
     This invention also relates to syringes which can be used only once, i.e., single-use syringes, and/or to syringes which utilize a built-in safety system which cannot be easily overridden by a user thereof. 
     This invention also relates to syringes which utilize one or more features disclosed in U.S. Ser. No. 12/951,925 filed on Nov. 22, 2010 or in combination with one or more features disclosed herein. 
     2. Discussion of Background Information 
     In hospitals, nursing home facilities and the like, injection of medicament into the body tissues of patients is done on a daily basis. Typical hypodermic syringes are provided with a barrel having a needle that is fixed or removably attached at one end thereof. A plunger typically having an elastomeric piston is movable within the barrel to load the barrel with liquid medicament by suction as the plunger and piston are moved within the barrel in a direction away from the needle. After the needle has penetrated the body tissues of the patient, as the direction of movement of the plunger and piston are reversed and the piston is forced toward the needle, medicament contained within the barrel will be injected through the needle into the body tissues. 
     After hypodermic syringes have been used in this manner, those syringes that are disposable present a significant problem to users, e.g., hospital or nursing home staff, because the possibility of inadvertent needle pricks subject personnel to the possibility of cross-contamination by, among other things, virile or bacterial contaminants that might be present on the needle after its use. In an effort to avoid the possibility of inadvertent needle pricks special waste containers are often provided at hospital facilities into which the used disposable hypodermic syringes are placed. These containers and the syringes contained therein are then disposed of in a specifically organized manner to insure against the possibility of inadvertent infectious contamination of nursing personnel. Further, refuse handlers and other persons who might inadvertently come into contact with the used hypodermic syringes are also subject to the same hazards. Often times the needles themselves are bent over so as to minimize the possibility of inadvertent needle pricks and to preclude the possibility of subsequent use of disposable hypodermic syringes. 
     In certain situations, medicaments are injected into patients and not quickly thereafter discarded properly. Instead, the used syringe is placed in a temporary position. After the procedure has ended, the syringe can be manually recovered for disposal. However, between the time of use and the time of disposal, there is the possibility that inadvertent needle pricks will occur. Accordingly, it is desirable to provide a suitable way protecting personnel, e.g., nursing personnel, paramedics and other persons, from the hazards of inadvertent needle pricks as they go about their daily tasks. 
     It is therefore desirable to provide a syringe that includes a system for rendering the needle thereof to a protected, completely encapsulated condition such that it is less likely to cause, after use, an inadvertent needle prick during its handling or during its disposal. It is also desirable to provide a syringe having the capability of causing the automatic retraction of the needle to a position inside the plunger of the syringe and maintaining the needle in its retracted position so that the needle of the syringe is always enclosed after its use, thus precluding the possibility that the needle might cause an accidental needle prick as the syringe is subsequently handled. It is also desirable to provide a syringe of the disposable type that is provided with facility for rendering it completely inoperative such that it can not be subsequently used. Additionally, it is desirable to provide for a syringe which also has minimal dead-space so that it can be ideally used for injecting very expensive medicaments with minimal waste. Finally, it is desirable to provide for a syringe which also has a system for selectively locking the plunger in a substantially fully depressed position so that the syringe can have dual, multiple, and/or parallel safety systems, i.e., one system can include causing the needle unit to retract into the plunger and another system can include locking the plunger in a substantially fully depressed position. 
     SUMMARY OF THE INVENTION 
     According to one non-limiting aspect of the invention there is provided a single-use injection device comprising a barrel, a plunger having a portion structured and arranged to move within the barrel, a needle connecting arrangement that one of: comprises a needle connecting interface adapted to mate with a needle interface and an end integrally formed with the barrel; comprises a spring biased needle connecting member having an interface adapted to mate with a needle interface and being movable from an initial position to a retracted position within the barrel; comprises a needle connecting interface adapted to mate with a needle interface and an end that can be non-removably connected with the barrel; comprises a luer-lock interface which can retract into the barrel when the plunger is substantially fully depressed; comprises a movable member which includes a standard interface and which can retract into the barrel when the plunger is substantially fully depressed; comprises a movable member which includes a standard interface and which can retract into the plunger; comprises a movable member which includes an interface to which a needle member can be removably connected and which can retract into the barrel by a spring upon a movement of the plunger; comprises a body connectable to one end of the barrel and a movable member which includes an interface to which a needle member can be connected and which can retract into the barrel by a spring upon a movement of the plunger; comprises a body installable on one end of the barrel and a movable member which includes an interface to which a needle member can be connected, a retention arrangement allowing the movable member to be retained in an initial position, and which can retract into the barrel by a spring; and comprises an assembly which includes a body connectable to the barrel, a member comprising a needle connecting interface and a retention element, and a spring biasing the member toward a retracted position. 
     In embodiments, the plunger is a hollow plunger. In embodiments, the plunger comprises a piston arranged at a proximal area of the plunger and an actuating end arranged in front of the piston. In embodiments, the plunger further comprises at least one of: the piston being an elastomer or rubber piston; a hollow space sized and configured to receive therein an injection needle; and a locking member adapted to lock with a locking member arranged on the barrel. In embodiments, the barrel and the plunger each comprise a synthetic resin material. In embodiments, the installable needle can be of any type whether packaged individually or in bulk or otherwise maintained in a sealed or sterile condition. 
     In embodiments, the barrel comprises at least one releasable retaining member. In embodiments, the at least one releasable retaining member comprises plural radially oriented releasable retaining members. In embodiments, the barrel comprises at least one deflectable retaining member. In embodiments, the at least one deflectable retaining member comprises plural radially oriented releasable retaining members. 
     In embodiments, the device further comprises at least one of: a locking arrangement that is structured and arranged to lock a portion of the needle connecting arrangement to a portion of the plunger; and a locking arrangement selectively locking a portion of the plunger to the barrel upon the plunger reaching a substantially fully depressed position. 
     In embodiments, when the plunger is moved to a full injection position, a member arranged within the needle connecting arrangement is automatically caused to retract into the plunger. In embodiments, when the plunger is moved to a full injection position, a member arranged within the needle connecting arrangement is automatically caused to retract into the barrel. 
     In embodiments, the device may further comprising a system providing an indication to the user in regards to a depressed position of the plunger. In embodiments, the device may further comprise a system providing an indication to the user that at least one of the plunger has reached a full injection position and the further forward movement of the plunger will cause a member coupled to a needle to automatically retract into the plunger. 
     According to another non-limiting embodiment of the invention, there is provided a single-use injection device comprising a barrel, a hollow plunger having a portion structured and arranged to move within the barrel, and a needle connecting arrangement comprising a spring and a needle member having a connecting interface, the needle member being movable automatically by the spring from an initial position to a retracted position within the barrel or the plunger. 
     According to another non-limiting embodiment of the invention, there is provided a single-use injection device comprising a barrel, a hollow plunger having a portion structured and arranged to move within the barrel and a needle connecting arrangement comprises a spring biased needle connecting member having an interface adapted to mate with a standard needle interface and being movable from an initial position to a retracted position within the barrel or the plunger. 
     In embodiments, the standard needle interface is a luer-lock interface. In embodiments, the standard needle interface relies substantially only upon contact between tapered surfaces. In embodiments, the standard needle interface relies substantially only upon friction fit contact. 
     According to another non-limiting embodiment of the invention, there is provided a method of using any of the injection devices described above, wherein the method comprises installing a needle member having a needle and a connecting interface on the injection device and moving the plunger relative to the barrel so as to cause medicine to exit through the needle. The needle member is capable of retracting into the plunger. 
     According to another non-limiting embodiment of the invention, there is provided a syringe which utilizes one or more features disclosed in U.S. Ser. No. 12/752,186 filed Apr. 1, 2010. The disclosure of this application is hereby expressly incorporated by reference hereto in its entirety. 
     According to another non-limiting embodiment of the invention, there is provided a syringe which utilizes one or more features disclosed in U.S. Ser. No. 12/951,925 filed on Nov. 22, 2010. The disclosure of this application is hereby expressly incorporated by reference hereto in its entirety. 
     According to another non-limiting embodiment of the invention, there is provided a syringe which utilizes one or more features disclosed in U.S. Ser. No. 12/752,186 filed Apr. 1, 2010 in combination with one or more features disclosed herein. 
     According to another non-limiting embodiment of the invention, there is provided a syringe which utilizes one or more features disclosed in U.S. Ser. No. 12/951,925 filed on Nov. 22, 2010 in combination with one or more features disclosed herein. 
     Other exemplary embodiments and advantages of the present invention may be ascertained by reviewing the present disclosure and the accompanying drawing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention is further described in the detailed description which follows, in reference to the noted plurality of drawings by way of non-limiting examples of exemplary embodiments of the present invention, in which like reference numerals represent similar parts throughout the several views of the drawings, and wherein: 
         FIG. 1  shows a side cross-section view of a first non-limiting embodiment of the device according to the invention. The needle is not shown in cross-section.  FIG. 1  shows the device with a safety cap installed thereon. The device is in an initial prior-use and/or packaged configuration; 
         FIG. 2  shows the device of  FIG. 1  after the safety cap is removed and in a ready-to-use position; 
         FIG. 3  shows the device of  FIG. 2  with the plunger retracted as would occur when medicine is caused to be suctioned into the syringe via the needle; 
         FIG. 4  shows the device with the plunger fully depressed as would occur during injection. In this position, the leading end of the plunger has moved deflectable retaining members out of locking engagement with the needle hub. Moreover, a rear end of the needle hub has caused an inner seal, i.e., a frangible plunger seal, to come out of sealing engagement with the needle hub; 
         FIG. 5  shows the device after the needle unit is caused to automatically retract into the plunger under the biasing force of a spring. The configuration shown in  FIG. 5  occurs automatically when the plunger reaches the position shown in  FIG. 4 ; 
         FIG. 5 a    shows a rear end view of the device of  FIG. 5 ; 
         FIG. 6  shows an enlarged partial view of the device of  FIG. 4  just before the plunger reaches the fully depressed position; 
         FIG. 7  shows an enlarged partial view of the device of  FIG. 4  just as the plunger reaches the fully depressed position thereby causing deflection of the retaining members and breaking of the frangible plunger seal caused by movement of the plunger against a rear end of the needle hub; 
         FIG. 8  shows a side cross-section view of the plunger used on the first non-limiting embodiment shown in  FIG. 1  and with the plunger piston and inner seal removed; 
         FIG. 9  shows a side view of the plunger of  FIG. 8  with the plunger piston installed thereon; 
         FIG. 10  shows a side cross-section view of the plunger piston used on the plunger shown in  FIG. 9 ; 
         FIG. 11  shows a side view of the plunger piston shown in  FIG. 10 ; 
         FIG. 12  shows a side view of the inner seal used on the plunger shown in  FIG. 1 ; 
         FIG. 13  shows a front end view of the inner seal shown in  FIG. 12 ; 
         FIG. 14  shows a side cross-section view of the inner seal shown in  FIG. 12 ; 
         FIG. 15  shows a side cross-section view of the device shown in  FIG. 1  with the plunger removed; 
         FIG. 16  shows a side cross-section view of the syringe body used in the device shown in  FIG. 1 ; 
         FIG. 17  shows a rear end view of the syringe body shown in  FIG. 16 ; 
         FIG. 18  shows a rear end view of another embodiment of the syringe body; 
         FIG. 19  shows a rear end view of still another embodiment of the syringe body; 
         FIG. 20  shows a side view of the needle unit used in the device shown in  FIG. 1 ; 
         FIG. 21  shows a side cross-section view of the needle unit shown in  FIG. 20 ; 
         FIG. 22  shows a rear end view of the needle unit shown in  FIG. 20 ; 
         FIG. 23  shows a side cross-section view of the spring used in the device shown in  FIG. 1 ; 
         FIG. 24  shows a rear end view of the spring shown in  FIG. 23 ; 
         FIG. 25  shows a side cross-section view of the needle sealing guide member used in the device shown in  FIG. 1 ; 
         FIG. 26  shows a side view of the needle sealing guide member shown in  FIG. 25 ; 
         FIG. 27  shows an enlarged partial view of another embodiment of a plunger which can be used on a device of the type shown in  FIG. 1 . The plunger is similar to that used in  FIG. 1  except that the inner seal is axially retained within the plunger via a separately formed ring; 
         FIG. 28  shows an enlarged partial view of a modified version of the device of  FIGS. 1 and 6 . In this embodiment, the device of  FIGS. 1 and 6  is modified to include a puncturable sealing washer to provided sealing between the needle and the syringe body; 
         FIG. 29  shows an enlarged partial view of another modified version of the device of  FIGS. 1 and 6 . In this embodiment, the device of  FIGS. 1 and 6  is modified to eliminate the needle sealing guide and to instead include a puncturable sealing washer to provided sealing between the needle and the syringe body; 
         FIG. 30  shows a side cross-section view of the device shown in  FIG. 29  with the needle unit and spring removed; 
         FIG. 31  shows a cross-section view through the section (indicated by arrows) shown in  FIG. 30 ; 
         FIG. 32  shows an enlarged partial view of another modified version of the device of  FIG. 1 . In this embodiment, the device of  FIG. 1  is modified to replace the integrally formed deflectable retaining members with a separately formed ring which is axially retained in the syringe body and which has the deflectable retaining members; 
         FIG. 33  shows an enlarged partial view of another modified version of the device of  FIG. 1 . In this embodiment, the device of  FIG. 1  is modified to include a locking system to prevent re-use of the device as well as an optional vent opening. The locking system locks the plunger to the syringe body when the plunger is fully or nearly fully depressed; 
         FIGS. 34 and 35  each show an enlarged partial view of another embodiment of a plunger which can be used on a device of the type shown in  FIG. 1 . The plunger is similar to that used in  FIG. 1  except that the inner seal is axially retained within the plunger via a recess and frangible projection system. In  FIG. 35 , the inner seal is axially retained within the plunger. In  FIG. 34 , the inner seal has been moved back sufficiently to cause the inner seal to break the frangible projection of the plunger; 
         FIG. 36  shows an enlarged partial view of another embodiment of a plunger which can be used on a device of the type shown in  FIG. 1 . The plunger is similar to that used in  FIG. 1  except that the inner seal is axially retained within the plunger via a recess and frangible projection system. In  FIG. 36 , the frangible projection of the plunger has annular v-shaped recesses which weaken the projection so that it breaks (via shearing forces) in a predictable manner; 
         FIG. 37  shows an enlarged partial view of another non-limiting embodiment of a device. The device is similar to that of  FIG. 1 , except that it utilizes a sealing member that utilizes a sealing member which can extend into the opening of the needle which prevents medication from passing into the needle when it is inserted into the distal end of the needle. The device also utilizes plural locking members which lock to the needle unit when the plunger is moved to the fully depressed position; 
         FIG. 38  shows a side cross section view of another embodiment of the invention. This embodiment is similar to that of  FIG. 1  except that a needle assembly portion (on left side) of the injection device is separated from the barrel/plunger assembly (on right side). The injection end of the barrel is configured to receive different needle assemblies which have the same rear interface, i.e., that part which connects to the barrel/plunger assembly. In this embodiment, a user can select from a number of different needle sizes and types and install the desired needle assembly on the injection device barrel/plunger assembly prior to use. The needle assembly is frictionally engaged with the barrel when full installed and can be such that it is non removable once installed; 
         FIG. 39  shows the device of  FIG. 38  when the needle assembly is fully installed on the barrel/plunger assembly and after the protective cover is removed. This is also a ready-to-use configuration; 
         FIG. 40  shows the device of  FIG. 39  after the plunger is withdrawn which would typically occur when a fluid or medicine is being force into or cause to enter the barrel through the needle; 
         FIG. 41  shows the device of  FIG. 39  with the plunger removed; 
         FIG. 42  shows an enlarged view of a front portion of  FIG. 39 ; 
         FIG. 43  shows a non cross-section view of  FIG. 42 ; 
         FIG. 44  shows an enlarged view of the needle assembly shown in  FIG. 39 ; 
         FIG. 45  shows an enlarged view of the barrel shown in  FIG. 39 . The seal is shown in an un-installed state; 
         FIG. 46  shows an enlarged view of a front portion of  FIG. 45 ; 
         FIG. 47  shows an enlarged view of an optional needle assembly which can be used in accordance with the invention. This embodiment is similar to that of  FIG. 44  except that a rear cylindrical surface includes plural frictional sealing projections to provide additional sealing and frictional retention with the barrel; 
         FIGS. 48 and 49  show enlarged views of another optional needle assembly which can be used in accordance with the invention. This embodiment is similar to that of  FIG. 44  except that a rear cylindrical surface includes a groove and an installable seal member to provide additional sealing and frictional retention with the barrel. In  FIG. 48 , the seal member is shown in the groove. In  FIG. 49 , the seal member is shown removed from the groove; 
         FIG. 50  shows an enlarged view of an optional configuration for a front portion of the barrel in accordance with the invention. This embodiment is similar to that of  FIG. 46  except that partial or interrupted thread(s) are used to axially retain the needle assembly on the barrel; 
         FIG. 51  shows an enlarged view of an optional configuration for a needle assembly in accordance with the invention. This embodiment is similar to that of  FIG. 44  except that partial or interrupted projections are used (which can threadably engage with the interrupted threads of  FIG. 50 ) to axially retain the needle assembly on the barrel; 
         FIG. 52  shows an enlarged view of an optional configuration for a front portion of the injection device in accordance with the invention. This embodiment is similar to that of  FIG. 42  except that deflectable locking projections are used to axially and non-removably retain the needle assembly on the barrel; 
         FIG. 53  shows a non cross-section view of  FIG. 52 ; 
         FIG. 54  shows how the needle assembly can be slid (along axial direction of arrow) into the barrel in order to form the device of  FIG. 52 ; 
         FIG. 55  shows an enlarged view of an optional configuration for a front portion of the injection device in accordance with the invention. This embodiment is similar to that of  FIG. 42  except that an outer locking sleeve having deflectable locking projections is used to axially and non-removably retain the needle assembly on the barrel. This embodiment also provides the user with a visual indication that the needle assembly is fully and properly installed on the barrel; 
         FIG. 56  shows the needle assembly used in the device of  FIG. 55 ; 
         FIG. 57  shows a non cross-section view of  FIG. 56 ; 
         FIG. 58  shows a cross-section view of  FIG. 57 ; 
         FIG. 59  shows a side cross section view of another embodiment of the invention. This embodiment is similar to that of  FIG. 38  except that the device additionally utilizes a removable retaining clip to ensure that the plunger is not fully depressed before or during installation of the needle assembly on the barrel/plunger assembly. Preferably, the user removes the retaining clip just prior to use of the injection device; 
         FIG. 60  shows a side cross section view of another embodiment of the invention. This embodiment is similar to that of  FIG. 59  except that a number of different needle assembles (i.e., assemblies with different needle lengths and diameters) are shown from which the user can select and install on the barrel/plunger assembly; 
         FIG. 61  shows a side cross section view of a packaged needle assembly in accordance with one non-limiting embodiment of the invention. The package utilizes a needle outer cover and a rear cover. When the user wishes to install the needle assembly, she first removes the rear cover from the front cover, installs the needle assembly on the barrel/plunger assembly, and then removes the needle cover; 
         FIGS. 62 and 63  show enlarged views of an optional configuration for a front portion of the injection device in accordance with the invention. This embodiment is similar to that of  FIG. 42  except that tapered locking projections are used to axially and non-removably retain the needle assembly on the barrel. Furthermore, an additional real seal member is used to provide additional sealing between the needle assembly and the barrel. In  FIG. 62 , the additional seal is shown in an installed position. In  FIG. 63 , the additional seal is shown in a non-installed position; and 
         FIG. 64  shows enlarged view of an optional configuration for a front portion of the injection device in accordance with the invention. This embodiment is similar to that of  FIG. 62  except that the additional real seal member is arranged in a groove formed in the barrel and the distal generally cylindrical surface of the needle assembly utilizes a tapered section to facilitate insertion of the needle assembly in the barrel. 
         FIG. 65  shows an enlarged view of a configuration for a front portion of the injection device in accordance with another non-limiting embodiment the invention. This embodiment is similar to that of  FIG. 52  except that the needle unit is separated into two main components. A first component or assembly utilizes a needle hub portion which is axially retained in a front section of the syringe and has a standard receiving interface. A second component or assembly utilizes a needle and a standard interface hub which can be sealingly connected to the standard receiving interface of the first component; 
         FIG. 66  shows the embodiment of  FIG. 65  with the second component about to be connected to the first component; 
         FIG. 67  shows the embodiment of  FIG. 65  with the second component connected to the first component. The syringe is now in a ready to use configuration; 
         FIG. 68  shows the embodiment of  FIG. 67  after the plunger (not shown) has been fully depressed and shows how the connected first and second components can automatically retract into the syringe by the spring; 
         FIG. 69-73  show enlarged views of a configuration for a front portion of the injection device in accordance with other non-limiting embodiments the invention. These embodiments are similar to that of  FIG. 65  with the exception of how sealing is provided between the first component and a front part of the syringe body; 
         FIG. 74  shows an enlarged view of a configuration for a front portion of the injection device in accordance with another non-limiting embodiment the invention. This embodiment is similar to that of  FIG. 1  except that first and second components are utilized as in the embodiment of  FIG. 65  and different sealing is provided between the first component and a front part of the syringe body; 
         FIG. 75  shows the embodiment of  FIG. 74  with the second component connected to the first component. The syringe is now in a ready to use configuration; 
         FIG. 76  shows the embodiment of  FIG. 74  as the plunger is being moved toward the fully depressed position; 
         FIG. 77  shows an enlarged view of a configuration for a front portion of the injection device in accordance with another non-limiting embodiment the invention. This embodiment is similar to that of  FIG. 74  except that a lockable separable plunger seal is utilized which can lock to the first component; 
         FIG. 78  shows the embodiment of  FIG. 77  with the plunger in the nearly fully depressed position and shows the lockable separable plunger seal locked to the first component; 
         FIG. 79  shows an enlarged view of a configuration for a front portion of the injection device in accordance with another non-limiting embodiment the invention. This embodiment is similar to that of  FIG. 74  except that the front portion of the syringe is threadably connected to a front end of the syringe main body; 
         FIG. 80  shows the embodiment of  FIG. 79  before the front portion of the syringe is threadably connected to the front end of the syringe main body; 
         FIG. 81  shows an enlarged view of a configuration for a front portion of the injection device in accordance with another non-limiting embodiment the invention. This embodiment is similar to that of  FIG. 79  except that the front portion of the syringe is differently threadably connected to a front end of the syringe main body; 
         FIG. 82  shows the embodiment of  FIG. 81  with various parts thereof being shown in a unconnected/unassembled state; 
         FIG. 83  shows certain parts of the embodiment of  FIG. 65  in an unconnected/unassembled state; 
         FIG. 84  shows one way in which a user can mount a front portion of on a syringe. According to this embodiment, the user can then remove the safety cover and install a needle member in the manner shown in  FIG. 67 ; and 
         FIG. 85  shows one way in which a user can mount a front portion of on a syringe. According to this embodiment, the user can then remove the safety cover and use the syringe. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings and first to  FIGS. 1-17 and 20-26  which shows a first embodiment of an injection device  1 . In embodiments, the device is a retractable hypodermic syringe. The syringe includes a generally elongate cylindrical barrel  10  having a transverse flange  11  arranged at a distal end of the barrel  10 . The barrel  10  includes a main generally cylindrical section  12 . A proximal end of the barrel  10  includes a reduced diameter section  13 . A safety cap  60  is removably disposed on a proximal end of the syringe body  10 . 
     A needle support  30  has a hub portion  31  that is substantially axially retained within a proximal area of the body  10  (see  FIG. 3 ) and includes a rear end surface which can contact an inner seal  25  of a plunger  20  as will be described in detail below. The needle support  30  also has a main needle portion  32  that has a rear end fixed within a needle hub  31  and a proximal end that is pointed or a puncturing end which extends out past the proximal end of the syringe body  10 . A sealing guide member  50  provides sealing between the needle  32  and the syringe body  10 , also allows the needle  32  to slide into the syringe  1  as will be described below. A spring  40  is arranged within the section  13  and the syringe body  10 , and in the configuration shown in  FIG. 2 , is fully or nearly fully compresses. The spring  40  biases the needle unit  30  towards a distal end of the syringe  1 . 
     Substantially arranged within the barrel  10  of the syringe is movably disposed a plunger  20 . The plunger  20 , like the syringe body  10 , includes an end flange  21  which is typically engaged by the thumb of the user while the transverse flange  11  is engaged by the fingers of the user in order to enable the plunger  20  to be forced into the barrel  10  for the purpose of expelling the medicament from the barrel  10  through the needle  32 . The plunger  20  additionally includes a generally cylindrical space  22  which is sized to receive therein the needle unit  30  (see  FIG. 5 ). A piston  23  (see  FIG. 9 ) is arranged on a proximal end of the plunger  10 . The plunger  20  also utilizes a proximal engaging end  24  which is sized and configured to engage with deflectable retaining members  15  (see  FIGS. 6 and 7 ) when the plunger  20  is fully depressed. An inner seal or sealing member  25  is arranged within the plunger  20 . As is apparent from  FIGS. 6 and 7 , the seal  25  has frangible circumferential projections which are sized and configured to break and/or shear off when the plunger  20  is depressed to the point where the seal  25  contacts the hub  31 . Before the projections of the seal  25  break, they provide sealing between the seal  25  and the plunger  20 . This sealing ensures that no medication passes into the plunger space  22  until the seal  25  is broken. 
     As is apparent from  FIGS. 6 and 7 , to unsure that the needle unit  30  is prevented from moving forwards when the plunger  20  is fully depressed, a plurality of stop projections or ribs  14  are arranged within the section  13  of the syringe body  10 . 
     The operation of the device shown  FIGS. 1-7  will now be described. Once the user obtains the device  1  shown in  FIG. 1 , he or she can then remove the safety cap  60 . The device  1  so shown in  FIG. 2  can now be used for, e.g., injection. This can occur when the user injects the needle  32  into a medication container and withdraws the plunger  20  as shown in  FIG. 3 . This causes medication fluid to fill the space in the body  10  between the plunger piston  23  and seal  25  and the sealing member  50 . As this point, the user can move the plunger  20  forwards slightly to remove any air in the syringe  1 . The needle  32  can then be injected into, e.g., tissue. Then, the user will depress the plunger  20  to cause the medication to pass out of the needle  32 . Once fully or nearly fully depressed, the proximal end  24  of the plunger  20  contacts the deflectable retaining members  15  (see  FIGS. 6 and 7 ) and causes them to deflect out of locking and/or retaining engagement with the hub  31 . Since engagement between the deflectable retaining members  15  and the hub  31  is the only mechanism which prevents the spring  40  from moving the needle unit  30  backwards, once this engagement is removed, the needle unit  30  will be forced backwards by the spring  40 . Also, once fully or nearly fully depressed, the seal  25  of the plunger  20  contacts the rear surface of the hub  31  (see  FIGS. 6 and 7 ). Since the ribs  14  prevent any forward movement of the hub  31 , contact between the seal  25  and the hub  31  causes the frangible sealing projections of the seal  25  to shear or break. At this point, the spring  40  automatically expands axially and pushes the needle unit  30  and seal  25  into the space  22  disposed inside the plunger  20  as shown in  FIG. 5 . This action withdraws the needle  32  into the syringe and renders the device  1  unusable. The device  1  of  FIG. 5  can then be safely disposed of without the user having to worry about being accidently pricked by the needle  32 , which is safely disposed inside the plunger  20 . 
     In embodiments, the engagement between the deflectable retaining members  15  and the hub  31  is removed or disengages prior to the sealing engagement between the seal  25  and the plunger  20 . In other embodiments, the engagement between the deflectable retaining members  15  and the hub  31  is removed or disengages just prior to the sealing engagement between the seal  25  and the plunger  20 . In embodiments, the engagement between the deflectable retaining members  15  and the hub  31  is not removed or disengaged until after the frangible sealing engagement between the seal  25  and the plunger  20  is broken. In embodiments, the engagement between the deflectable retaining members  15  and the hub  31  is not removed or disengaged until just after the frangible sealing engagement between the seal  25  and the plunger  20  is broken. In embodiments, the force required to unlock or remove the engagement between the deflectable retaining members  15  and the hub  31  is less than that required to break the sealing engagement between the seal  25  and the plunger  20 . In embodiments, the force required to unlock or remove the engagement between the deflectable retaining members  15  and the hub  31  is greater than that required to break the sealing engagement between the seal  25  and the plunger  20 . In embodiments, the force required to unlock or remove the engagement between the deflectable retaining members  15  and the hub  31  is substantially equal to that required to break the sealing engagement between the seal  25  and the plunger  20 . In embodiments, a noise is produced (providing an auditory signal to the user) when the engagement between the deflectable retaining members  15  and the hub  31  is removed. In embodiments, a noise is produced (providing an auditory signal to the user) when the sealing engagement between the seal  25  and the plunger  20  is broken. In embodiments, a visual indication is produced (providing a visual signal to the user) when the engagement between the deflectable retaining members  15  and the hub  31  is removed. In embodiments, a visual indication is produced (providing a visual signal to the user) when the sealing engagement between the seal  25  and the plunger  20  is broken. Such visual indicators can be facilitated by making the plunger  20  and body  10  substantially transparent and/or translucent. 
       FIGS. 8 and 9  show views of the plunger  20  used on the first non-limiting embodiment shown in  FIG. 1 . The plunger  20 , in embodiments, is a one-piece integrally formed member to which is axially secured a piston  23  and an inner seal  25 . The plunger  20  includes a distal flange  21 , a main cylindrical section  22 , a generally cylindrical proximal end  24 , one or more inner generally circumferential tapered recesses  26 , a generally cylindrical recess  27  sized and configured to receive therein and axially retain the piston  23 , and a generally cylindrical space  28 . 
       FIGS. 8 and 9  show views of the piston  23  used on the plunger of  FIGS. 8 and 9 . The piston  23 , in embodiments, is a one-piece integrally formed member to which is axially secured within the recess  27  of the plunger  20 . In embodiments, it can be substantially similar at pistons conventionally used in syringes which include plural external circumferential sealing projections. 
       FIGS. 12-14  show views of the inner seal  25  used on the plunger of  FIGS. 8 and 9 . The seal  25 , in embodiments, is a one-piece integrally formed member to which is axially secured to an inner portion of the plunger  20 . In embodiments, the seal  25  includes a distal or rear surface  25   a , one or more tapered external circumferential projections  25   b , and a proximal surface  25   c . The one or more tapered external circumferential projections  25   b  each extend into one of the recesses  26  of the plunger  20 . The tapered external circumferential projections  25   b  are designed to be frangible and sized and configured to shear upon experiencing a predetermined force applied to the surface  25   c . The shape, i.e., rearward orientation, of the tapered external circumferential projections  25   b  is such that a force applied to the surface  25   c  will cause the projections  25   b  to grip recesses  26  by a greater amount and such that a force applied to the surface  25   a  will cause the projections  25   b  to grip recesses  26  by a lesser amount. In embodiments, a force applied to the surface  25   a  will cause the projections  25   b  to start to move out of engagement with the recesses  26  by a significant amount without breaking. 
       FIGS. 15-17  show how the syringe body  10  used on the device of  FIG. 1  receives therein the seal guide  50 , the needle member  30  and the spring  40  before receiving therein the plunger  20  of  FIGS. 8 and 9 . The body  10 , in embodiments, is a one-piece integrally formed member. The body  10  includes a distal flange  11 , a main cylindrical section  12 , a generally cylindrical proximal end  13 , one or more inner radially oriented spaced-apart ribs  14 , plural deflectable retaining members  15  which are equally spaced-apart and which are sized and configured to engage with the circumferential recess  33  of the needle unit  30  (see  FIG. 20 ), and a generally cylindrical opening  17  sized and configured to receive therein (in a sealing and/or press-fit manner) the generally cylindrical surface  50   a  of the sealing guide  50  (see  FIG. 26 ). In embodiments, two oppositely arranged deflectable retaining members  15  are utilized. In embodiments, three equally spaced deflectable retaining members  15  are utilized. In embodiments, between four and eight equally spaced deflectable retaining members  15  are utilized.  FIG. 18  shows an optional embodiment wherein section  13 ′ utilizes four equally spaced deflectable retaining members  15 ′ and four ribs  14 ′ which have the same orientation.  FIG. 19  shows an optional embodiment wherein section  13 ″ utilizes four equally spaced deflectable retaining members  15 ″ and four ribs  14 ″ which are offset with respect to one another. These systems/configurations can be utilized on any of the herein disclosed device embodiments. 
       FIGS. 20-22  show views of the needle unit  30  used on the device  1  of  FIG. 1 . The needle unit  30 , in embodiments, can be a one-piece integrally formed member. The needle unit  30 , in embodiments, utilizes a one-piece needle hub  31  and a one-piece needle  32  that has a distal end secured (e.g., press-fit) within an opening the hub  31 . The needle hub  31 , in embodiments, also utilizes a tapered section  36  and a circumferential groove or recess  33  which can receive therein the free ends of the deflectable gripping members  15  (see  FIG. 6 ). In embodiments, the needle  32  has a main lumen  34  and a puncturing end  35 . In embodiments, the needle  32  can be substantially similar at pistons conventionally used in syringes which include plural external circumferential sealing projections. 
       FIGS. 23 and 24  show views of the spring  40  used on the embodiment of  FIG. 1 .  FIG. 23  shows the spring  40  in an expanded or relaxed position. In the position shown in  FIG. 1 , the spring  40  is fully or nearly fully compressed. Expansion of the spring  40  causes the needle unit  30  to retract fully into the plunger  20  (see  FIG. 5 ). 
       FIGS. 25 and 26  show views of the sealing guide  50  used on the embodiment of  FIG. 1 . The seal  50  has a generally cylindrical section  50   a , a tapered section  50   b , and a generally cylindrical opening  50   c . The generally cylindrical section  50   a  is sized and configured to sealingly and frictionally engage with opening  17  in the body  10 . The tapered section  50   b  is sized and configured to sealingly and frictionally engage with a corresponding tapered surface of the body  10 . The generally cylindrical opening  50   c  is sized and configured to sealingly engage with the needle  32 . The seal  50 , in embodiments, can be a one-piece integrally formed member. 
       FIG. 27  shows an enlarged partial view of another embodiment of a plunger  20 ′ which can be used on a device of the type shown in  FIG. 1 . The plunger  20 ′ is similar to that used in  FIG. 1  except that the inner seal  25 ′ is axially retained within the plunger  20 ′ via a separately formed ring  29 ′. The ring  29 ′ is seated in a circumferential recess formed in the seal  25 ′. In embodiments, a distal circumferential shoulder is sized and configured to break when the plunger  20 ′ is fully depressed. In embodiments, a ring  29 ′ is a frangible ring and is sized and configured to break when the plunger  20 ′ is fully depressed. As with the previous embodiments, the plunger  20 ′ includes a proximal engaging end  24 ′ and a piston  23 ′. This system/configuration can be utilized on any of the herein disclosed device embodiments. 
       FIG. 28  shows an enlarged partial view of a modified version of the device of  FIG. 1 . In this embodiment, the device of  FIG. 1  is modified to include a puncturable sealing washer  70  to provided sealing between the needle  32 ′ and the guide  50  and/or syringe body  10 ″. The needle unit  30 ′ is also modified to include a generally cylindrical section  37 ′. As with the previous embodiments, the device utilizes ribs  14 ″ and deflectable retaining members  15 ″. This system/configuration can be utilized on any of the herein disclosed device embodiments. 
       FIGS. 29-31  show views of another modified version of the device of  FIG. 1 . In this embodiment, the device of  FIG. 28  is modified to remove the ribs and the guide seal and instead sealing is provided between the opening  17   IV  of the syringe body  10   IV  and the needle  32 ′. As with the previous embodiments, the device utilizes deflectable retaining members  15   IV . This system/configuration can be utilized on any of the herein disclosed device embodiments. 
       FIG. 32  shows an enlarged partial view of another modified version of the device of  FIG. 1 . In this embodiment, the device of  FIG. 1  is modified to replace the integrally formed deflectable retaining members with a separately formed ring  16   V  which is axially retained in the syringe body  10   V  via a projection and recess securing arrangement. The ring  16   V  is a one-piece member that has the deflectable retaining members  15   V . This system/configuration can be utilized on any of the herein disclosed device embodiments. 
       FIG. 33  shows an enlarged partial view of another modified version of the device of  FIG. 1 . In this embodiment, the device of  FIG. 1  is modified to include a locking system to prevent re-use of the device as well as an optional vent opening. The locking system has the form of one or more projections LP and one or more recesses LR adapted to receive therein the locking projection LP. The locking system locks the plunger  120  to the syringe body  110  when the plunger  120  is fully or nearly fully depressed. Other configurations can also be utilized such as arranging the locking projections LP on the syringe body  110  and the locking recesses LR on the plunger  120 . The projection LP can be, in embodiments, continuous or intermittent and the recess LR can be a circumferential recess. The device can also be modified to utilize an optional vent opening VO in the plunger  120 . The locking system prevents re-use of the device. The systems shown in  FIG. 33  can be utilized on any of the herein disclosed device embodiments. 
       FIGS. 34 and 35  each show an enlarged partial view of another embodiment of a plunger which can be used on a device of the type shown in  FIG. 1 . The plunger is similar to that used in  FIG. 1  except that the inner seal  125 ′ is axially retained within the plunger body  122 ′ via a recess and frangible projection FP. In  FIG. 35 , the inner seal  125 ′ is axially retained within the plunger. In  FIG. 34 , the inner seal  125 ′ has been moved back sufficiently under the action of a force F to cause the inner seal  125 ′ to break the frangible projection FP of the plunger. The systems shown in  FIGS. 34 and 35  can be utilized on any of the herein disclosed device embodiments. 
       FIG. 36  shows an enlarged partial view of another embodiment of a plunger which can be used on a device of the type shown in  FIG. 1 . The plunger is similar to that used in  FIG. 1  except that the inner seal  125 ″ is axially retained within the plunger body  122 ″ via a recess and a selectively weakened frangible projection FP′. In  FIG. 36 , the frangible projection FP′ of the plunger has annular v-shaped recesses which weaken the projection FP′ so that it breaks (via shearing forces) in a predictable manner. The system shown in  FIG. 36  can be utilized on any of the herein disclosed device embodiments. 
       FIG. 37  shows an enlarged partial view of another non-limiting embodiment of a device. The device is similar to that of  FIG. 1 , except that it utilizes a sealing member  25 ″ that utilizes a sealing member SM which can extend into the distal opening of the needle  32 ″ so as to prevent medication from passing into the needle  32 ″ when it is inserted into the distal end of the needle  32 ″. The device also utilizes plural locking members LM which lock to a circumferential engaging projection EP of the needle unit  31 ″ when the plunger is moved to the fully depressed position (indicated by arrow). Once locked to each other, the seal  25 ″ and needle unit  30 ″ retract into the plunger as a unit. The system shown in  FIG. 37  can be utilized on any of the herein disclosed device embodiments. 
     Referring now to the drawings and to  FIGS. 38-46  which shows another embodiment of an injection device  1000 . The device  1000  is made of two main components or assemblies. One component is a syringe/plunger assembly SBA which includes a syringe barrel  1010  and a plunger  1020 . Another component is a needle or needle-hub assembly NHA which includes a needle assembly body  1018 , a biasing member  1040  and a needle member  1030 . In embodiments, the device is a retractable hypodermic syringe. The syringe includes a generally elongate cylindrical barrel  1010  having a transverse flange  1011  arranged at a distal end of the barrel  1010 . The barrel  1010  includes a main generally cylindrical section  1012 . A proximal end of the barrel  1010  includes an increased diameter section  1013 . A safety cap  1060  is removably disposed on a proximal end of the device  1000 . 
     A needle support  1030  has a hub portion  1031  that is substantially axially retained within a distal area of the body  1018  (see  FIG. 44 ) and includes a rear end surface which can contact an inner seal  1025  of a plunger  1020 , in a manner similar to that used in the embodiment of  FIG. 1 . The needle support  1030  also has a main needle portion  1032  that has a rear end fixed within a needle hub  1031  and a proximal end that is pointed or a puncturing end which extends out past the proximal end of the body  1018 . A sealing guide member  1050  provides sealing between the needle  1032  and the proximal end  1018   d  of the body  1018 , also allows the needle  1032  to slide into the syringe  1000  as will be described below. A biasing member having the form of a spring  1040  is arranged within the body  1018 , and in the configuration shown in  FIG. 44 , is fully or nearly fully compressed. The spring  1040  biases the needle unit  1030  towards a distal end of the syringe  1000 . 
     With reference to  FIGS. 39 and 40 , it can be seen that substantially arranged within the barrel  1010  of the syringe is movably disposed a plunger  1020 . The plunger  1020 , like the syringe body  1010 , includes an end flange  1021  which is typically engaged by the thumb of the user while the transverse flange  1011  is engaged by the fingers of the user in order to enable the plunger  1020  to be forced into the barrel  1010  for the purpose of expelling the medicament from the barrel  1010  through the needle  1032 . The plunger  1020  additionally includes a generally cylindrical space  1022  which is sized to receive therein the needle unit  1030  (similar to that shown in  FIG. 5 ). A piston  1023  is arranged on a proximal end of the plunger  1010 . The plunger  1020  also utilizes a proximal engaging end  1024  which is sized and configured to engage with deflectable retaining members  1015  (similar to that shown in  FIGS. 6 and 7 ) when the plunger  1020  is fully depressed. An inner seal or sealing member  1025  is arranged within the plunger  1020 . In a similar manner to that of  FIGS. 6 and 7 , the seal  1025  has frangible circumferential projections which are sized and configured to break and/or shear off when the plunger  1020  is depressed to the point where the seal  1025  contacts the hub  1031 . Before the projections of the seal  1025  break, they provide sealing between the seal  1025  and the plunger  1020 . This sealing ensures that no medication or fluid passes into the plunger space  1022  until the seal  1025  is broken. 
     As was the case in  FIGS. 6 and 7 , to unsure that the needle unit  1030  is prevented from moving forwards when the plunger  1020  is fully depressed, a plurality of stop projections or ribs  1014  are arranged within the body  1018  (see  FIG. 42 ). However, unlike the embodiment of  FIG. 1 , because the instant embodiment provides for a separate and installable needle assembly, sealing is needed between the needle assembly and the barrel. Such sealing is provided by a sealing member  1080 . As can be seen in  FIGS. 42-46 , the sealing member  1080  is sized and configured to slide within spacing  1019  and to seat in an annular groove  1019   b  defined by the surface  1019  and an annular projection  1019   a . Sealing is ensured when the seal  1080  is caused to be compressed between flange  1018   b  and the groove  1019   b . Non-limiting materials for the sealing member  1080  can include those typically used for sealing in syringes or other similar medical devices. 
     When the needle assembly is installed on the barrel  1010  as shown in  FIG. 39 , the generally cylindrical surface  1018   c  is sized and configured to frictionally engage with an inner cylindrical surface of the barrel  1010 . In embodiments, both of these surfaces are slightly tapered to provide for better sealing. Also when the needle assembly is installed on the barrel  1010  as shown in  FIG. 39 , the flange  1018   b  arranged on main cylindrical surface  1018   a  of the body  1018  is sized and configured to frictionally engage with an inner slightly tapered surface  1019  of the barrel  1010 . This ensures that the needle assembly is essentially wedged into the front end of the barrel  1010  and has the following functions: prevents leaking during injection, ensures that the needle assembly does not come out of frictional engagement with the barrel, and causes compression of the seal  1080 . 
     The operation of the device shown  FIGS. 38-46  will now be described. Once the user obtains the desired needle assembly NHA and is ready to install it on a syringe body assembly SBA as shown in  FIG. 38 , he or she can grip the safety cap  1060  and install the needle assembly NHA on the syringe assembly SBA. Once assembled, the user can remove the safety cover  1060 . The device so shown in  FIG. 39  can now be used for, e.g., injection. This can occur when the user injects the needle  1032  into a medication container and withdraws the plunger  1020  as shown in  FIG. 40 . This causes medication fluid to fill the space in the body  1010  between the plunger piston  1023  and seal  1025  and the sealing member  1050 . As this point, the user can move the plunger  1020  forwards slightly to remove any air in the syringe. The needle  1032  can then be injected into a surface, e.g., tissue. Then, the user will depress the plunger  1020  to cause the medication to pass out of the needle  1032 . Once fully or nearly fully depressed, the proximal end  1024  of the plunger  1020  contacts the deflectable retaining members  1015  (see e.g.,  FIGS. 6 and 7 ) and causes them to deflect out of locking and/or retaining engagement with the hub  1031 . Since engagement between the deflectable retaining members  1015  and the hub  1031  is the only mechanism which prevents the spring  1040  from moving the needle unit  1030  backwards, once this engagement is removed, the needle unit  1030  will be forced backwards by the spring  1040 . Also, once fully or nearly fully depressed, the seal  1025  of the plunger  1020  contacts the rear surface of the hub  1031 . Since the ribs  1014  prevent any forward movement of the hub  1031 , contact between the seal  1025  and the hub  1031  causes the frangible sealing projections of the seal  1025  to shear or break. At this point, the spring  1040  automatically expands axially and pushes the needle unit  1030  and seal  1025  into the space  1022  disposed inside the plunger  1020 . This action withdraws the needle  1032  into the syringe and renders the device  1000  unusable. The once-used device  1000  can then be safely disposed of without the user having to worry about being accidently pricked by the needle  1032 , which is safely disposed inside the plunger  1020 . 
     In embodiments, the engagement between the deflectable retaining members  1015  and the hub  1031  is removed or disengages prior to the sealing engagement between the seal  1025  and the plunger  1020 . In other embodiments, the engagement between the deflectable retaining members  1015  and the hub  1031  is removed or disengages just prior to the sealing engagement between the seal  1025  and the plunger  1020 . In embodiments, the engagement between the deflectable retaining members  1015  and the hub  1031  is not removed or disengaged until after the frangible sealing engagement between the seal  1025  and the plunger  1020  is broken. In embodiments, the engagement between the deflectable retaining members  1015  and the hub  1031  is not removed or disengaged until just after the frangible sealing engagement between the seal  1025  and the plunger  1020  is broken. In embodiments, the force required to unlock or remove the engagement between the deflectable retaining members  1015  and the hub  103   s  less than that required to break the sealing engagement between the seal  1025  and the plunger  1020 . In embodiments, the force required to unlock or remove the engagement between the deflectable retaining members  1015  and the hub  1031  is greater than that required to break the sealing engagement between the seal  1025  and the plunger  1020 . In embodiments, the force required to unlock or remove the engagement between the deflectable retaining members  1015  and the hub  1031  is substantially equal to that required to break the sealing engagement between the seal  1025  and the plunger  1020 . In embodiments, a noise is produced (providing an auditory signal to the user) when the engagement between the deflectable retaining members  1015  and the hub  1031  is removed. In embodiments, a noise is produced (providing an auditory signal to the user) when the sealing engagement between the seal  1025  and the plunger  1020  is broken. In embodiments, a visual indication is produced (providing a visual signal to the user) when the engagement between the deflectable retaining members  1015  and the hub  1031  is removed. In embodiments, a visual indication is produced (providing a visual signal to the user) when the sealing engagement between the seal  1025  and the plunger  1020  is broken. Such visual indicators can be facilitated by making the plunger  1020  and body  1010  substantially transparent and/or translucent. 
       FIG. 47  shows an enlarged view of an optional needle assembly which can be used in accordance with the invention. This embodiment is similar to that of  FIG. 44  except that a rear cylindrical surface  1018 ′ c  of the body  1018 ′ includes plural frictional sealing projections  1018 ′ c   1  and  1018 ′ c   2  to provide additional sealing and frictional retention with the barrel  1010 . This sealing/frictional engagement can be used with any of the embodiments shown or described with reference to  FIGS. 38-63 . 
       FIGS. 48 and 49  show enlarged views of another optional needle assembly which can be used in accordance with the invention. This embodiment is similar to that of  FIG. 44  except that a rear cylindrical surface  1018 ″ c  includes a groove  1018 ″ e  and an installable seal member or O-ring  1018 ″ c   1  to provide additional sealing and frictional retention with the barrel. In  FIG. 48 , the seal member  1018 ″ c   1  is shown in the groove  1018 ″ e . In  FIG. 49 , the seal member  1018 ″ c   1  is shown removed from the groove  1018 ″ e . This sealing/frictional engagement can be used with any of the embodiments shown or described with reference to  FIGS. 38-63 . 
       FIGS. 50 and 51  show an optional configuration for a front portion of the barrel and the needle assembly in accordance with the invention. This embodiment is similar to that of  FIG. 46  except that partial or interrupted thread(s)  2019   c  are used to axially retain the needle assembly body  2018  on the barrel  2010 . The arrangement of  FIGS. 50 and 51  functions as follows. When the user wishes to install the needle assembly shown in  FIG. 51  in the open end  2013  of the barrel  2010  shown in  FIG. 50 , he or she slides the needle assembly into the opening  2019  and causes the projections  2018   b  to threadably engage with the partial threads  2019   c . This forces the projections  2018   b  into contact with the seal member  2080 . As with previous embodiments, the seal  2080  is seated in a groove  2019   b  defined by an annular projection  2019   a  and the needle assembly has a body  2018 , a sealing member  2050 , a spring  2040 , an outer generally cylindrical surface  2018   a  having the projections  2018   b , as well as a distal generally cylindrical surface  2018   c  and a needle unit  2030  which can retract into the plunger (not shown). Moreover, because the projections  2018   b  are spaced apart (and is not a continuous flange), sealing will not be ensured by the sealing member  2080 . As such, it is desirable to use sealing in at least one other location such as those shown in, e.g.,  FIGS. 47, 48, 62 and 64 . The arrangement of  FIGS. 50 and 51  provides for a quick or easy threaded connection between the needle assembly and the syringe/plunger assembly. This provides for quick connect (and also disconnect—although not necessarily desirable) of the same merely by rotating the needle assembly relative to the barrel by a small angle of rotation. 
       FIGS. 52-54  show an optional configuration for a front portion of the injection device in accordance with the invention. This embodiment is similar to that of  FIG. 42  except that deflectable locking projections  3019   d  are used to axially and non-removably retain the needle assembly body  3018  on the barrel  3010 . The arrangement of  FIGS. 52-54  functions as follows. When the user wishes to install the needle assembly in the manner shown in  FIG. 54  in the open end  3013  of the barrel  3010 , he or she slides the needle assembly into the opening  3019  and causes the projections  3019   d  to deflect outwardly until the flange  3018   b  contacts the seal  3080 . The projections  3019   d  then automatically deflect back inwardly to an original or a locking position shown in  FIG. 52 . The projections  3018   d  then function to axially press the flange  3018   b  into contact with the seal member  3080 . Each projection  3019   d  moves within a space or opening  3019   e  formed in the section  3013  of the barrel  3010 . As with previous embodiments, the needle assembly has a body  3018 , a sealing member  3050 , a spring  3040 , an outer generally cylindrical surface  3018   a  having the flange  3018   b , as well as a distal generally cylindrical surface  3018   c  and a needle unit  3030  which can retract into the plunger (not shown). Sealing will be ensured by the sealing member  3080 . However, it may also be desirable to use additional sealing in at least one other location such as those shown in, e.g.,  FIGS. 47, 48, 62 and 64 . The arrangement of  FIGS. 52-54  provides for a quick or easy slide-on or snap connection between the needle assembly and the syringe/plunger assembly. This provides for quick non-releasable automatic connection (by preventing disconnection) of the same merely by sliding the needle assembly into the barrel by a predetermined amount—while also ensuring or enabling proper sealing at the same time. The sound, i.e., a click sound, provided by the projections  3019   d  assuming the original locked position shown in  FIG. 52  (after being deflected outwardly) provides an indication to the user that the needle assembly is fully and properly installed and that sealing of the same is ensured. 
       FIGS. 55-58  show another optional configuration for a front portion of the injection device in accordance with the invention. This embodiment is similar to that of  FIG. 42  except that an outer locking sleeve  4018   f  is used to axially and non-removably retain the needle assembly body  4018  on the barrel  4010 . The arrangement of  FIGS. 55-58  functions as follows. When the user wishes to install the needle assembly in the open end  4013  of the barrel  4010 , he or she slides the needle assembly onto the open end  4013  and causes the members  4018   j  having projections  4018   i  to deflect outwardly until the projections  40181  lock to the annular shoulder between section  4013  and section  4012  as shown in  FIG. 55 . The members  4018   j  automatically deflect back inwardly to an original or a locking position shown in  FIG. 55  when the needle assembly is fully installed. The projections  4018   i  thus ensure that the flange  4018   b  is pressed into contact with the seal member  4080 . Each member  4018   j  can deflect because of slots or openings  4018   h . An annular space  4018   g  thus receives therein the end  4013  of the barrel  4010 . As with previous embodiments, the needle assembly has a body  4018 , a sealing member  4050 , a spring  4040 , a proximal hub section  4018   d , an outer generally cylindrical surface  4018   a  having the flange  4018   b , as well as a distal generally cylindrical surface  4018   c  and a needle unit  4030  which can retract into the plunger (not shown). The needle unit  4030  is retained in position by the deflectable members  4015  and includes a needle hub  4031  and a needle. Sealing will be ensured by the sealing member  4080 . However, it may also be desirable to use additional sealing in at least one other location such as those shown in, e.g.,  FIGS. 47, 48, 62 and 64 . The arrangement of  FIGS. 55-58  provides for a quick or easy slide-on or snap connection between the needle assembly and the syringe/plunger assembly. This provides for quick non-releasable automatic connection (by preventing disconnection) of the same merely by sliding the needle assembly onto the barrel by a predetermined amount—while also ensuring or enabling proper sealing at the same time. The sound, i.e., a click sound, and the visual image of the fingers  4018   j  assuming a generally cylindrical position as provided by the projections  4018   i  assuming the original locked position shown in  FIG. 55  (after being deflected outwardly) provides both a visual and audible indication to the user that the needle assembly is fully and properly installed and that sealing of the same is ensured. 
       FIG. 59  shows another embodiment of the invention. This embodiment is similar to that of  FIG. 38  except that the device additionally utilizes a removable retaining clip RC to ensure that the plunger is not fully depressed before or during installation of the needle assembly NHA on the barrel/plunger assembly SBA. Preferably, the user removes the retaining clip RC after installation of the needle assembly NHA on the barrel/plunger assembly SBA and just prior to use of the injection device. The removable retaining clip RC can also be used on any of the other herein disclosed embodiments. 
       FIG. 60  shows an embodiment similar to that of  FIG. 59  and utilizing a number of different needle assembles NHA 1 , NHA 2  and NHA 3  (i.e., assemblies with different needle lengths and diameters). The user can select one of the needle assemblies and install the selected one on the barrel/plunger assembly SBA. Each needle assembly has the same back-end configuration which allows it to be mounted on a common barrel/plunger assembly SBA. As is apparent from  FIG. 60 , needle assembly NHA 1  utilizes a smaller diameter and shorter length needle than that of needle assembly NHA 3 . Needle assembly NHA 2  utilizes a smaller diameter needle than that of needle assembly NHA 3 . Preferably, each herein disclosed embodiment allows a user to select from a number of different needle assemblies for mounting on a common barrel/plunger assembly SBA. 
       FIG. 61  shows a packaged needle assembly NHAP in accordance with one non-limiting embodiment of the invention. The package utilizes a needle outer cover  1060 A and a rear cover  1060 B. When the user wishes to install the needle assembly, he or she first removes the rear cover  1060 B from the front cover  1060 A, installs the needle assembly on the barrel/plunger assembly, and then removes the needle cover  1060 A. 
       FIGS. 62 and 63  show another optional configuration for a front portion of the injection device in accordance with the invention. This embodiment is similar to that of  FIG. 42  except that tapered locking projections LP are used to axially and non-removably retain the needle assembly on the barrel  5010 . The projections LP axially retain the flange  5018   b  of the body  5018  and force it against the seal  5080 . The needle assembly, like those previously described, includes a spring  5040 , deflectable retaining members  5015 , and a needle unit  5030 . Furthermore, an additional real seal member ASM is arranged in a retaining groove RG and is used to provide additional sealing between the body  5018  and the barrel  5010 . In  FIG. 62 , the additional seal ASM is shown in an installed position. In  FIG. 63 , the additional seal ASM is shown in a non-installed position. This additional sealing arrangement can be used with any of the embodiments shown or described with reference to  FIGS. 38-61 . 
       FIG. 64  shows another optional configuration for a front portion of the injection device in accordance with the invention. This embodiment is similar to that of  FIG. 62  except that tapered section  6018   f  is used to help guide the body  6018  into the barrel  6010  during installation and especially into the secondary seal ASM′. The projections axially retain the flange of the body  6018  and force it against the seal  6080 . The needle assembly, like those previously described, includes a spring  6040 , deflectable retaining members  6015 , and a needle unit  6030 . Furthermore, the additional real seal member ASM′ is arranged in a retaining groove RG′ formed in the barrel  6010  and is used to provide additional sealing between the generally cylindrical surface  6018   c  of the body  6018  and the barrel  6010 . This additional sealing arrangement can be used with any of the embodiments shown or described with reference to  FIGS. 38-61 . 
       FIGS. 65-68 and 83  show a front portion of the injection device in accordance with another embodiment of the invention. This embodiment is similar to that of  FIG. 52  except that except that the needle unit is separated into two main components. A first component or assembly  7030 A utilizes a needle hub portion  7031  which is axially retained in a front section of the syringe via deflectable members  7015  and has a universal or standard receiving interface SI. The standard receiving interface SI can be of any type such as a luer lock or luer-lok. In this way, the same or different needles (or types of needles) having or sharing a common and/or the same connecting interface can be coupled to the syringe. A second component or assembly  7030 B utilizes a needle N and a standard interface hub NH which can be sealingly connected to the standard receiving interface SI of the first component  7030 A. A sealing ring  7050  (see  FIG. 83 ) is utilized to seal the member  7031  to the body  7018 . A spring  7040  biases the member  7031  towards a retracted position. A needle assembly body  7018  is axially and sealingly retained on the barrel  7010  via members  7019   d  and seal  7080  as in the arrangement of  FIG. 52  and functions as follows. When the user wishes to install the needle assembly  7030 A/ 7018  (with or without the needle member  7030 B) in the manner similar to that shown in  FIG. 54  in the open end  7019  of the barrel  7010 , he or she slides the needle assembly into the opening  7019  and causes the projections  7019   d  to deflect outwardly until the flange  7018   b  contacts the seal  7080 . The projections  7019   d  then automatically deflect back inwardly to an original or a locking position shown in  FIG. 65 . The projections  7018   d  then function to axially press the flange  7018   b  into contact with the seal member  7080 . Each projection  7019   d  moves within a space or opening formed in the section  7013  of the barrel  7010 . As with previous embodiments, the needle assembly has a body  7018 , a sealing member  7050 , a spring  7040 , an outer generally cylindrical surface having the flange  7018   b , further includes a two-component a needle unit  7030 A and  7030 B which can retract (see  FIG. 68 ) into the plunger (not shown). The arrangement of  FIGS. 65-68 and 83  provides for a quick or easy slide-on or snap connection between the needle assembly and the syringe/plunger assembly and also allows different size or types of needle members  7030 B having a common interface to be connected to the syringe. This provides for quick non-releasable automatic connection (by preventing disconnection) of the body  7018  merely by sliding the needle assembly into the barrel by a predetermined amount—while also ensuring or enabling proper sealing at the same time. The sound, i.e., a click sound, provided by the projections  7019   d  assuming the original locked position shown in  FIG. 65  (after being deflected outwardly) provides an indication to the user that the needle assembly is fully and properly installed and that sealing of the same is ensured. 
       FIG. 69  shows a configuration for a front portion of the injection device in accordance with another non-limiting embodiment the invention. This embodiment is similar to that of  FIG. 65  with the exception of how sealing is provided between the first component  7030 A′ and the body  7018 ′. In this embodiment, a larger seal ring  7050 ′ functions to seal a forward facing axial surface of the member  7031 ′ to a rear-facing annular surface of the body  7018 ′. A spring  7040 ′ biases the member  7031 ′ towards a retracted position. The needle assembly body  7018 ′ is axially and sealingly retained on the barrel  7010 ′ via members  7019   d′.    
       FIG. 70  shows a configuration for a front portion of the injection device in accordance with another non-limiting embodiment the invention. This embodiment is similar to that of  FIG. 69  with the exception of how sealing is provided between the first component  7030 A″ and the body  7018 ″. In this embodiment, a pressure activated seal ring  7050 ″ functions to seal a forward facing axial surface of the member  7031 ″ to a rear-facing annular surface of the body  7018 ″. 
       FIG. 71  shows a configuration for a front portion of the injection device in accordance with another non-limiting embodiment the invention. This embodiment is similar to that of  FIG. 69  with the exception of how sealing is provided between the first component  7030 A′″ and the body  7018 ′. In this embodiment, a larger seal ring  7050 ″ functions to seal a forward facing axial surface of the member  7031 ′″ to a rear-facing annular surface of the body  7018 ″. Additional sealing is provided by a circumferential projection P. 
       FIGS. 72 and 73  show a configuration for a front portion of the injection device in accordance with another non-limiting embodiment the invention. This embodiment is similar to that of  FIG. 69  with the exception of how sealing is provided between the first component  7030 A IV  and the body  7018   IV . In this embodiment, a seal ring  7050   IV  functions to seal an outer circumferential surface of the member  7031   IV  to a rear-facing annular surface of the body  7018   IV . The seal ring  7050   IV  is maintained in sealing position by the spring  7040   IV . 
       FIGS. 74-76  show a configuration for a front portion of the injection device in accordance with another non-limiting embodiment the invention. This embodiment is similar to that of  FIG. 1  except that first and second components are utilized as in the embodiment of  FIG. 65 . Additionally, different sealing, i.e., seal ring  8050 , is provided between the first component  8030 A and the integrally formed front part  8013  of the syringe body  8010 . The arrangement of  FIG. 74  provides for a quick or easy connection between the needle assembly  8030 B and the syringe/plunger assembly and also allows different size or types of needle members  8030 B having a common interface to be connected to the first component  8030 A of the syringe so that both the components  8030 A/ 8030 B can retract into the plunger  8020 . 
       FIGS. 77 and 78  show a front portion of the injection device in accordance with another non-limiting embodiment the invention. This embodiment is similar to that of  FIG. 74  except that a lockable separable plunger seal  8025 ′ is utilized which can lock to the first component  8030 A′. The arrangement of  FIGS. 77 and 78  provides for a quick or easy connection between a needle assembly (shot shown in  FIGS. 77 and 78 ) and the syringe/plunger assembly and also allows different size or types of needle members having a common interface to be connected to the first component  8030 A′ of the syringe so that both the components  8030 A′ (with the needle member mated thereto) can retract into the plunger  8020 ′ when the plunger  8020 ′ is fully depressed. As can be appreciated from a review of  FIGS. 77 and 78 , as the plunger  8020 ′ moves toward the fully depressed position, a forward projecting end of the seal  8025 ′ enters into an opening formed in member  8030 A′ as shown in  FIG. 77 . This movement continues until the projecting end locks into the member  8030 A′. Simultaneously, a rear-facing annular projecting flange of the member  8030 A′ engages with the seal  8025 ′ and causes it to deflect radially inwardly and thereby becomes unsealed (or breaks the sealing engagement) with the plunger  8020 ′ as shown in  FIG. 78 . During this movement, the forward end of the plunger  8020 ′ also causes deflection or disengagement of the members  8015 ′ retaining the member  8030 A′. As this point, nothing remains to prevent the spring  8040 ′ from causing the member  8030 A′ (with the needle member attached to a front end thereof and the seal  8025 ′ locked to a rear end thereof) to retract into the plunger  8020 ′. 
       FIGS. 79 and 80  show a front portion of the injection device in accordance with another non-limiting embodiment the invention. This embodiment is similar to that of  FIG. 74  except that the front portion  9013  of the syringe is threadably connected to a front end of the syringe main body  9010 . The member  9030 A which contains a standard interface is mounted to the front portion  9013 . As shown in  FIG. 80 , external threads ET of the front portion  9013  are configured to threadably engage with internal threads IT of the body  9010 . This system or arrangement has at least two advantageous. First, it allows for easier installation of the member  9030 A. It also allows a user to attach different types of front sections  9013  onto a common syringe body  9010 . 
       FIGS. 81 and 82  show a front portion of the injection device in accordance with another non-limiting embodiment the invention. This embodiment is similar to that of  FIG. 79  except that it is differently threadably connected to a front end of the syringe main body. The front portion  9013 ′ of the syringe is threadably connected to a front end of the syringe main body  9010 ′. The member  9030 A′ which contains a standard interface is however mounted to the front end of the body  9010 ′. As shown in  FIG. 82 , external threads ET′ of the front portion  9013 ′ are configured to threadably engage with internal threads IT′ of the body  9010 ′. This system or arrangement has at least one advantageous. It allows for easier installation of the member  9030 A′ during assembly of the syringe. As in the previous embodiment, this embodiment utilizes a spring  9040 ′ and a seal  9050 ′. 
       FIG. 84  shows one way in which a user can mount a front portion, e.g., the embodiment of  FIG. 65 , on a syringe. According to this embodiment, the user can remove a safety cover NHA′ and install a needle member (similar to that shown installed in  FIG. 84 ) in the manner shown in  FIG. 67 . The safety cover NHA′ is used to maintain the interface in a sterile condition until the front portion is installed on the syringe body. To use the syringe shown in  FIG. 84 , a user removes the safety cover NHA′, installs a needle member, and depresses the plunger of the syringe during injection. Once fully depressed, the syringe is rendered un-usable and the needle member remains safely disposed in the plunger. 
       FIG. 85  shows another way in which a user can mount a front portion of on a syringe. According to this embodiment, the syringe is packaged with a needle member already installed on the standard interface and maintained in a sterile condition by the safety cover NHA′. The user can install the front portion on the syringe body and then remove the safety cover NHA′ and use the syringe. 
     The devices described herein can also utilize one or more features disclosed in prior art documents expressly incorporated by reference in pending U.S. patent application Ser. No. 11/616,196 (Publication No. 2008/0154212). This application and the documents expressly incorporated therein is hereby expressly incorporated by reference in the instant application. Furthermore, one or more of the various parts of the device can preferably be made as one-piece structures by e.g., injection molding, when doing so reduces costs of manufacture. Non-limiting materials for most of the parts include synthetic resins such as those approved for syringes, blood collection devices, or other medical devices. Furthermore, the invention also contemplates that any or all disclosed features of one embodiment may be used on other disclosed embodiments, to the extent such modifications function for their intended purpose. 
     It is noted that the foregoing examples have been provided merely for the purpose of explanation and are in no way to be construed as limiting of the present invention. While the present invention has been described with reference to an exemplary embodiment, it is understood that the words which have been used herein are words of description and illustration, rather than words of limitation. Changes may be made, within the purview of the appended claims, as presently stated and as amended, without departing from the scope and spirit of the present invention in its aspects. Although the present invention has been described herein with reference to particular means, materials and embodiments, the present invention is not intended to be limited to the particulars disclosed herein; rather, the present invention extends to all functionally equivalent structures, methods and uses, such as are within the scope of the appended claims.