Abstract:
A safety shield for use with a hypodermic syringe device is disclosed. The safety shield is moveable relative to the syringe barrel between retracted position and a needle containing position. In the retracted position, the syringe device may be used to inject the needle into the patient. After the medication has been injected or as the needle is withdrawn from the patient, in its operative mode the shield automatically extends from its retracted position to a needle containing position to shield the point of the needle to prevent accidental sticks and without further input from the operator to render the syringe unusable after a single injection.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a division of and claims benefit of U.S. application Ser. No. 14/613,919 filed Feb. 4, 2015, to be issued as U.S. Pat. No. 9,623,193 on Apr. 18, 2017, which was a continuation-in-part of and claimed benefit of U.S. application Ser. No. 13/312,520 filed Dec. 6, 2011, now abandoned. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    Medical care of individuals requires the widespread use of needles for taking blood samples, intravenous drug delivery, and the introduction or removal of other fluids via cannula, needles, or syringes. In the current context, the use of hypodermic needles to deliver plasma, anesthetics, or other medications has become commonplace in medicine, science, veterinary medicine, and biotechnology. The use of a hypodermic needle typically involves first inserting a needle into the patient, injecting a substance or withdrawing a substance as required, and then removing the needle from the patient. In most applications, the withdrawn and contaminated needle must be handled very carefully during disposal to avoid needle stick injury. 
         [0003]    To help prevent health care workers from becoming injured, guards have been developed to block the tip of these needles after use. Indeed, needle stick protection for medical professionals has become of particular importance in recent years because of the prevalence of potentially fatal infectious diseases, such as, for example, Acquired Immune Deficiency Syndrome (AIDS) and hepatitis, that can be transmitted by the exchange of bodily fluids through inadvertent wounds caused by accidental needle tip pricks after withdrawal from infected patients. Accordingly, many kinds of needle protection devices are available for providing post injection needle stick protection. 
         [0004]    However, many of devices are cumbersome and interfere with a single-handed procedure, or require a conscious action by the operator to activate the needle shield, or require additional complicated pieces to attach a needle guard to the needle tip. Some needle guards require the user to reposition the hand to manually activate a second mechanism that then engages the needle guard, adding to the complexity of the design, manufacture and use of the hypodermic needle assembly. With other designs, it is possible for a user to accidentally insert a finger into the open distal end of the needle guard sleeve and thus come into contact with the contaminated needle tip. Other designs require that the user either slide or apply the needle shield to the tip of the needle by hand, significantly raising the risk of unintentional contact with the needle tip. 
         [0005]    Accordingly, it is desirable to provide a device for injecting medication or withdrawing fluid wherein a contaminated needle is enclosed after use, which overcomes the aforementioned drawbacks. The needle enclosing device should be automatically activated immediately following the medication injection cycle requiring no further input from the operator. 
       BRIEF SUMMARY OF THE INVENTION 
       [0006]    A safety shield for use with a hypodermic syringe device is disclosed. The safety shield is moveable relative to the syringe barrel between retracted position and a needle-containing position. In the retracted position, the syringe device may be used to inject the needle into the patient. After the medication has been injected or as the needle is withdrawn from the patient, in its operative mode the shield extends from its retracted position to a needle-containing position to shield the point of the needle to prevent accidental sticks and without further control from the operator to render the syringe unusable after a single injection. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    The invention will be described in conjunction with the following drawings in which like reference numerals designate like elements and wherein: 
           [0008]      FIG. 1  is a perspective view of a first embodiment of the present invention; 
           [0009]      FIG. 2  is an exploded perspective view of the first embodiment of the present invention illustrating the components of the embodiment; 
           [0010]      FIG. 3  is a cross-sectional view of the first embodiment of the present invention as it is provided to the medical professional in a packaged condition; 
           [0011]      FIG. 4  is a cross-sectional view taken along line  4 - 4  of  FIG. 3 ; 
           [0012]      FIG. 5  is an enlarged cross-sectional view of the first embodiment of the present invention; 
           [0013]      FIG. 6  is a cross-sectional view taken along line  6 - 6  of  FIG. 5 ; 
           [0014]      FIG. 7  is a cross-sectional view taken along line  7 - 7  of  FIG. 5 ; 
           [0015]      FIG. 8  is a cross-sectional view taken along line  8 - 8  of  FIG. 5 ; 
           [0016]      FIG. 9  is a cross-sectional view of the first embodiment of the present invention illustrating withdrawal of a liquid from a vial by withdrawing the plunger from the syringe barrel; 
           [0017]      FIG. 10  is a cross-sectional view of the first embodiment of the present invention illustrating injection of a medicament at an injection site of a patient; 
           [0018]      FIG. 11  is an enlarged cross-sectional view of the first embodiment of the present invention illustrating the manner for actuating and deploying the safety shield over the needle; 
           [0019]      FIG. 12  is an enlarged cross-sectional view of the first embodiment of the present invention illustrating the manner for deploying the safety shield over the needle; 
           [0020]      FIG. 13  is an enlarged cross-sectional view of the first embodiment of the present invention illustrating the safety shield deployed over the needle; 
           [0021]      FIG. 14  is a perspective view of a second embodiment of the present invention; 
           [0022]      FIG. 15  is an exploded perspective view of the second embodiment of the present invention illustrating components of the embodiment; 
           [0023]      FIG. 16  is a cross-sectional view of the second embodiment of the present invention illustrating the safety shield held in a retained position; 
           [0024]      FIG. 17  is an enlarged cross-sectional view of the second embodiment of the present invention illustrating the safety shield held in the retained position; 
           [0025]      FIG. 18  is a cross-sectional view taken along line  18 - 18  of  FIG. 17 ; 
           [0026]      FIG. 19  is a cross-sectional view taken along line  19 - 19  of  FIG. 17 ; 
           [0027]      FIG. 20  is a cross-sectional view of the second embodiment of the present invention illustrating withdrawal of a liquid from a vial by withdrawing the plunger from the syringe barrel; 
           [0028]      FIG. 21  is a cross-sectional view of the second embodiment of the present invention illustrating injection of a medicament at an injection site of a patient; 
           [0029]      FIG. 22  is a cross-sectional view of the second embodiment of the present invention illustrating the pivotable locking projection pivoting out of the needle-carrier during deployment of the outer shield over the needle; 
           [0030]      FIG. 23  is a cross-sectional view of the second embodiment of the present invention illustrating opposed deformable members collapsing within opposed grooves of the needle-carrier during deployment of the outer shield over the needle; 
           [0031]      FIG. 24  is a cross-sectional view of the second embodiment showing the outer shield in a deployed needle-containing position; 
           [0032]      FIG. 25  is an enlarged cross-sectional view of a portion of the second embodiment showing the outer shield in the deployed needle-containing position; 
           [0033]      FIG. 26  is a perspective view of a third embodiment of the present invention in the hand of a user; 
           [0034]      FIG. 27  is an exploded perspective view of the third embodiment of the present invention illustrating the components of the embodiment; 
           [0035]      FIG. 28  is a cross-sectional view of the third embodiment of the present invention; 
           [0036]      FIG. 29  is an enlarged cross-sectional view of the third embodiment of the present invention; 
           [0037]      FIG. 30  is a cross-sectional view taken along line  30 - 30  of  FIG. 29 ; 
           [0038]      FIG. 31  is a cross-sectional view taken along line  31 - 31  of  FIG. 29 ; 
           [0039]      FIG. 32  is a cross-sectional view of the third embodiment of the present invention illustrating withdrawal of a liquid medicament from a vial by withdrawing a plunger from the syringe barrel; 
           [0040]      FIG. 33  is a cross-sectional view of the third embodiment of the present invention illustrating injection of a medicament at an injection site of a patient; 
           [0041]      FIG. 34  is an enlarged cross-sectional view of the third embodiment of the present invention illustrating the manner for deploying the outer safety shield; 
           [0042]      FIG. 35  is an enlarged cross-sectional view of the third embodiment of the present invention illustrating the outer shield being deployed towards an extended needle-containing position; 
           [0043]      FIG. 36  is an enlarged cross-sectional view of the third embodiment of the present invention showing the outer shield deployed in the extended needle-containing position; 
           [0044]      FIG. 37  is a perspective view of a fourth embodiment of the present invention; 
           [0045]      FIG. 38  is an exploded perspective view of the fourth embodiment of the present invention illustrating the components of this embodiment; 
           [0046]      FIG. 38A  is an exploded perspective view of a portion of a spring-loaded alternative version of the fourth embodiment of the present invention; 
           [0047]      FIG. 39  is a cross-sectional view of the fourth embodiment of the present invention showing the outer shield disposed in a retracted position; 
           [0048]      FIG. 39A  is a cross-sectional view of a portion of the spring-loaded alternative version of the fourth embodiment; 
           [0049]      FIG. 40  is an enlarged cross-sectional view of the fourth embodiment of the present invention showing the outer shield disposed in the retracted position; 
           [0050]      FIG. 41  is a cross-sectional view taken along line  41 - 41  of  FIG. 40 ; 
           [0051]      FIG. 42  is a cross-sectional view taken along line  42 - 42  of  FIG. 40 ; 
           [0052]      FIG. 43  is a cross-sectional view of the fourth embodiment of the present invention illustrating withdrawal of a liquid medicament from a vial by withdrawing the plunger from the syringe barrel; 
           [0053]      FIG. 44  is a cross-sectional view of the fourth embodiment of the present invention illustrating injection of a medicament at an injection site of a patient; 
           [0054]      FIG. 45  is an enlarged cross-sectional view of the fourth embodiment of the present invention showing the outer shield being deployed towards the needle-containing position; 
           [0055]      FIG. 46  is an enlarged cross-sectional view of the fourth embodiment of the present invention showing the outer shield moving towards the needle-containing position; 
           [0056]      FIG. 47  is a cross-sectional view of the fourth embodiment of the present invention showing the outer shield deployed in the needle-containing position; 
           [0057]      FIG. 47A  is an enlarged cross-sectional view of a portion of a spring-loaded alternative version of the fourth embodiment of the present invention showing the outer shield deployed in the needle-containing position; 
           [0058]      FIG. 48  is a perspective view of a fifth embodiment of the present invention; 
           [0059]      FIG. 49  is an exploded perspective view of the fifth embodiment of the present invention illustrating the components of this embodiment; 
           [0060]      FIG. 50  is an enlarged cross-sectional view of a portion of the fifth embodiment of the present invention illustrating the outer shield retained in a retracted position; 
           [0061]      FIG. 51  is an enlarged cross-sectional view of a portion of the fifth embodiment of the present invention illustrating the outer shield retained in the retracted position; 
           [0062]      FIG. 52  is an enlarged cross-sectional view of a portion of the fifth embodiment of the present invention illustrating the outer shield deployed in the needle-containing position; 
           [0063]      FIG. 53  is a cross-sectional view taken along line  53 - 53  of  FIG. 52 ; 
           [0064]      FIG. 54  is a perspective view of a sixth embodiment of the present invention; 
           [0065]      FIG. 55  is another perspective view of the sixth embodiment of the present invention; 
           [0066]      FIG. 56  is an exploded perspective view of the sixth embodiment of the present invention illustrating the components of this embodiment; 
           [0067]      FIG. 57  is an enlarged cross-sectional view of the sixth embodiment of the present invention illustrating the manner for deploying the outer shield shown retained in a retracted position; 
           [0068]      FIG. 58  is a cross-sectional view taken along line  58 - 58  of  FIG. 57 ; 
           [0069]      FIG. 59  is an enlarged cross-sectional view of the sixth embodiment of the present invention illustrating a manner for drawing a fluid, e.g., a medicament, into the syringe barrel via a needle by retracting a plunger; 
           [0070]      FIG. 60  is an enlarged cross-sectional view of the sixth embodiment of the present invention illustrating the manner for deploying the outer shield shown retained in a retracted position; and, 
           [0071]      FIG. 61  is an enlarged cross-sectional view of the sixth embodiment of the present invention illustrating the outer shield moved to the deployed needle-containing position. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0072]    Referring now in detail to the various figures of the drawings wherein like reference characters refer to like parts, there is shown at  10  in  FIGS. 1 through 4  a safety syringe assembly that includes a syringe barrel  14 , a plunger  18 , and a hypodermic needle  22  having a needle tip  26 . The assembly  10  is arranged for use with a variety of commercially available needles. The assembly  10  also includes a needle protector cap  30  arranged to snap onto collar  19  at the distal end of the safety syringe assembly  10 . The syringe barrel  14  is generally cylindrical and includes a forward end having a reduced diameter nozzle  34  ( FIG. 2 ) adapted to receive the needle  22 . The syringe barrel  14  defines a reservoir within which a fluid, e.g., a medicament, may be contained. The needle  22  or needle cannula (those terms being used interchangeably herein) extends axially and in the forward direction from the syringe barrel  14  and includes a forward tip  26 . The needle  22  is in fluid communication with the reservoir through the reduced diameter nozzle  34  ( FIG. 2 ). The syringe barrel  14  is preferably formed of a transparent or translucent molded plastic such as polyethylene, polypropylene, or polycarbonate. 
         [0073]    The barrel  14  has an outwardly extending flange  38  located towards a proximal end thereof which facilitates gripping of the syringe barrel  14  with the user&#39;s fingers  42  ( FIG. 1 ) when it is desired to move the plunger  18  relative to the barrel  14  linearly for normal use, such as when moving the plunger through an injection stroke to inject a fluid, e.g., a medicament into a patient. The finger flange  38  may be annular or oblong. The portion of the syringe barrel  14  forward of the finger flange  38  is substantially transparent and includes volume measuring indicia  44  ( FIG. 2 ) on the surface thereof to enable a user to determine the volume of fluid within the barrel  14 . For example, the syringe barrel  14  may hold up to 3.0 ml in volume, however, may hold other volumes greater or lesser. 
         [0074]    Referring now to  FIGS. 2, 4 and 5 , a portion  15  of the syringe barrel  14  extends rearward from the finger flange  38  and is slightly larger in diameter than the forward portion and includes a pair of opposed elongated slots  46 ,  50  each bounded by a peripheral wall. Each peripheral wall of the slots  46 ,  50  includes an end wall  54 ,  58  located at the rear end of the syringe barrel  14 . Each end wall  54 ,  58  serves as a first catch member, for example, a syringe barrel catch member, to retain an outer shield  94  in a retracted position wherein the needle  22  is exposed for use. In one embodiment a second catch member is located on the syringe barrel distally from the first catch member and arranged to engage the engagement member when the outer shield reaches the needle-containing position. As best shown in  FIGS. 2, 5, and 13 , the finger flange  38  is provided with interior surfaces  61  and  63  that serve as the second catch members for the shield  94 , as will be explained below. While in the preferred embodiment the second catch member is associated with the finger flange  38 , it should be obvious to one skilled the art that it can be located anywhere that will prevent continued shield movement, for example, anywhere along slot  46 ,  50 . 
         [0075]    Shield  94  does not have an operatively positioned outwardly extending finger gripping flange, preferably not within its rearward one-half, and most preferably not within its rearward one-third. Operatively positioned is defined as not in a location that would allow a user to keep the shield effectively retracted with their fingers once released. Cap collar  19  is not considered to be an outwardly extending finger gripping flange as it is located beyond effective finger reach during use. For comparison, see the barrel finger flange  38 . 
         [0076]    The plunger assembly  17  comprising plunger rod  18  extends within the open rear end of the syringe barrel  14  and is reciprocally disposed therein. The plunger is releasably connected at its rounded and reduced diameter first end to a dislodgeable stopper  62  positioned within the reservoir of the syringe barrel  14 . The stopper  62  is sometimes referred to as the “rubber piston” or “rubber stopper” and may be molded of a suitable biocompatible material. The stopper  62  may be collapsible or compressible. The shank of the plunger  18  extends out of the open rear end of the syringe barrel  14  includes a thumb pad  66  or thumb press area for receiving delivery pressure for pressing the plunger into the syringe barrel to deliver the fluid, e.g., medicament. The terms “thumb pad” and “thumb press area” are used interchangeably herein and designate a region coupled to or otherwise formed on an end of the plunger and which may be depressed by the thumb  70  ( FIG. 1 ) or finger of a user during use of the medical device. The plunger  18  may be formed of a suitable molded plastic. 
         [0077]      FIGS. 1-5  depict the safety syringe assembly  10  generally in a condition in which it is assembled, packaged and shipped, e.g., prior to use. It can be seen that the hypodermic needle  22  is in an exposed state with the needle protected by the cap  30 , and the plunger  18  is in an advanced position within the syringe barrel  14 . The outer shield  94  is disposed in the retracted position over the syringe barrel  14  and is provided with a front opening  96  to allow the needle  22  to extend therethrough. Thus, in the illustrated example of  FIGS. 1-5 , the syringe  10  is ready to draw a fluid, e.g., a medicament, into the barrel  14 , via the needle  22 , for example, by retracting the plunger  18 , e.g., in the direction of arrow  82  to the position illustrated in  FIG. 9 . 
         [0078]    The syringe assembly may be pre-filled with a fluid, e.g., a medicament. Alternatively, as shown in  FIG. 9 , the fluid may be withdrawn from a storage vial  74  having a membrane  78  sealed to the upper end thereof. That is, the vial  74  containing the fluid is inverted and the tip  26  of the needle  22  is pierced through the membrane  78 . The fluid, e.g., the medicament, is withdrawn from the vial into the syringe barrel  14  by moving the plunger  18  in the direction of arrow  82  in  FIG. 9 . Thereafter, once a designated amount of fluid is withdrawn into the syringe barrel  14 , the needle may be removed from the vial and the syringe device is ready for use on a patient. Referring now to  FIG. 10 , the contents of syringe barrel  14  may be injected into an injection site  86 , such as any subcutaneous or intra-muscular location on a person where an injection is needed. Injection surface  91  is the skin above injection site  86 . The user causes needle  22  to pierce the skin  91  above the injection site  86 . The user places his fingers  42  on the outwardly extending finger flanges  38  using his thumb  70  on the thumb pad  66  applies pressure to press the plunger  18  into the syringe barrel  14  along the injection stroke to expel the fluid, e.g., medicament through the needle  22  and deliver the fluid into the injection site  86  of the person. As best shown in  FIG. 5 , the plunger  18  will travel through the injection stroke within the syringe barrel  14  until it reaches a terminus within the syringe barrel  14  at which point the medicament has been expelled through the needle  22  into the injection site  86 . 
         [0079]    A driving member, such as an elastic or resilient biasing means, here illustrated as a compression spring  90  of very small diameter and preferably made from stainless steel or other metal, is mounted over a reduced diameter nozzle  34 . Referring now to  FIGS. 1-4 , the compression spring  90  is of such a diameter that it also fits within the interior of an outer shield  94  that is disposed over the syringe barrel  14 . The compression spring  90  is provided for urging the outer shield  94  from a retracted position wherein the compression spring  90  is in a compressed state and the hypodermic needle  26  is exposed ( FIGS. 1-5 ) to a needle-containing position wherein the outer shield  94  extends forwardly to cover the needle  22 , which is best shown in  FIG. 13 . To retain the outer shield  46  in the retracted position, the outer shield  46  includes a pair of opposed hook members  98  and  102  (best seen in  FIGS. 2, 3 , and  9 ) that extend rearwardly. The hook members  98  and  102  are arranged to engage the catch members  54  and  58  of the syringe barrel  14  to retain the outer shield  94  over the syringe barrel  14  in the retracted position. In particular, referring now to  FIG. 5 , hook member  98  is provided with a rear facing ramp  98   a  and a front facing ramp  98   b  defining a slot therebetween in which the catch  54  is arranged to be held captive when the shield  94  is retracted. Hook member  102  is provided with a rear facing ramp  102   a  which is arranged to engage catch  58  for the same purpose. 
         [0080]    Referring now to  FIGS. 2 and 5 , plunger rod assembly  17  comprises plunger rod  18 , thumb pad  66 , and plunger rod assembly release member  106 . In a preferred embodiment, extending forwardly from the thumb pad  66  is the plunger rod assembly release member, for example, release collar  106  including an inclined surface  110  (best shown in  FIG. 5 ). Release member  106  may also be, for example, tabs comprising an inclined surface. (not shown). 
         [0081]    As best demonstrated for comparison purposes in  FIGS. 5 and 12 , as the thumb pad  66  is pressed in the direction of the injection stroke and the plunger is moved towards and reaches its terminus within the syringe barrel, the inclined surface  110  of the release collar  106  will contact and apply force to the inclined surfaces  98   a  and  102   a  of the hook members deflecting them inwardly and causing them to release from the catches  54  and  58  of the syringe barrel  14  as the plunger  18  is pushed further along in the direction of the injection stroke. Once the inward moving releasing member, for example, hook members  98  and  102  clear the catches  54  and  58 , the compressed spring  90  will expand to its normal position thus causing the outer shield  94  to move from its retracted position ( FIGS. 11 and 12 ) to a needle-containing position ( FIG. 13 ). Optionally, the syringe assembly  10  may be arranged such that a suitable amount of pressure must be applied in the direction of the injection stroke to cause the stopper  62  to compress slightly or distort against the interior wall of the syringe barrel  14  before the hook members  98  and  102  will release from the catches  54  and  58 .  FIG. 5  illustrates the stopper  62  in an undistorted condition while  FIGS. 11 and 12  illustrate the stopper  62  in a compressed or distorted condition. In this manner, the outer shield  94  will not move from its retracted position to cover the needle  22  until after all fluid, e.g., medicament, has been dispensed from the syringe barrel  14 . 
         [0082]    Referring now to  FIG. 13 , as the outer shield  94  travels to the needle-containing position, the hook member  98  will again deflect inwardly as the ramp  98   b  travels around catch surface  61  of finger flange  38 . The hook member  98  will return to its undeflected positions to retain the catch member  61  between ramps  98   a  and  98   b . Ramp  98   a  and hook  102  serve to stop forward movement of the outer shield  46  beyond the needle-containing position while ramp  98   b  prevents backward movement of the outer shield  94  towards the retracted position, thus locking the outer shield in the needle-containing position. In the needle-containing position the entire needle  22  including the tip  26  is safely housed within the shield  94 . As best shown in  FIGS. 2 and 8 , the surface of the outer shield  94  is provided with a magnifier  107  on opposed sides thereof. The magnifier  107  extends over the length of the volume measuring indicia  44  located on the surface of the syringe barrel  14  and magnifies said indicia  44  to ease reading of said indicia  44 . 
         [0083]    Referring now in detail to the various figures of the drawings wherein like reference characters refer to like parts, there is shown at  200  in  FIGS. 14 through 17  a second embodiment safety syringe assembly that includes a syringe barrel  214 , a plunger  218 , and a hypodermic needle  222  having a needle tip  226 . The syringe  200  also includes a removable needle protector cap  230  ( FIGS. 14, 15 ) arranged to snap onto the distal end of the safety syringe assembly  200 . 
         [0084]    The syringe barrel  214  defines a reservoir within which a fluid, e.g., a medicament, may be contained and dispensed therefrom. The barrel  214  has an outwardly extending flange  238  located towards the proximal end of the barrel  214  which facilitates gripping of the barrel with the user&#39;s fingers  242  ( FIG. 14 ) when it is desired to move the plunger  218  relative to the barrel  214  linearly for normal use, such as when moving the plunger  218  through an injection stroke to inject a fluid, e.g., a medicament into a patient. The finger flange  238  may be annular or oblong. The portion of the syringe barrel  214  forward of the finger flange  238  is substantially transparent and includes volume measuring indicia  240  ( FIG. 14 ) on the surface thereof to enable a user to determine the volume of fluid within the barrel  214 . Referring now to  FIGS. 15 and 17 , at its most distal end, the barrel  214  includes an open nozzle  216  in which a needle-carrier  274  is positioned. Referring now to  FIGS. 14-17 , as the syringe barrel  214  extends rearwardly from the finger flange  238 , it is slightly larger in diameter than the barrel extending forward from the finger flange  238 . 
         [0085]    The plunger  218  extends within the open rear end of the syringe barrel  214  and includes a first end with a stopper  262  positioned within the reservoir of the syringe barrel  214 . The stopper is adapted to provide a slideable seal with the interior surface of the syringe barrel for expelling fluids through the distal end of the syringe barrel  214 . The stopper  262  is in fluid tight engagement with the interior surface. The stopper  262  is preferably made of pliable rubber, thermoplastic rubber, plastic, or similar material. The stopper  262  is sometimes referred to as the “rubber piston” or “rubber stopper”. Preferably, the stopper  262  may be substantially non-compressible. A second end of the plunger  218  extending out of the open rear end of the syringe barrel  214  includes a thumb pad  266  or thumb press area for receiving delivery pressure for pressing the plunger into the syringe barrel to deliver the fluid, e.g., medicament. The stopper  262  may be depressed by the thumb  270  ( FIG. 14 ) or finger of a user during use of the syringe device. As shown in the figures, the diameter of the stopper  262  is approximately equal to the inside diameter of the syringe barrel  214  it extends into. 
         [0086]    Referring now to  FIGS. 15 through 17 and 22-25 , the hypodermic needle  222  is held within the needle-carrier  274 . The needle-carrier  274  comprises a generally tubular body having a through hole provided at its center for securing the hypodermic needle  222  therein. The needle-carrier  274  includes a smaller diameter fore section  278  in which a slot  282  is located, a comparatively larger diameter midsection  286 , on which a pair of opposed grooves  290  are provided, and a “t-head” aft section  294  including an annular groove over which a generally cylindrical seal  298  may be positioned and retained. The seal  298 , formed of a suitable biocompatible material, is adapted to provide a watertight fit with the interior surface of the syringe barrel  214  so that fluid in the barrel reservoir is directed into the needle  222  for delivery to the injection site of the person. As mentioned above, the needle-carrier  274  is positioned within the open nozzle  216  of the syringe barrel  214  and is retained therein by a pivotable locking projection  302  disposed at the distal end of the syringe barrel  214 . The locking projection  302  is arranged to extend radially inwardly and lodge within the slot  282  of the needle-carrier  274  to retain the needle-carrier  274  in a retained position and to prevent movement of the needle-carrier  274  in the proximal direction with respect to the syringe body  214 . The needle-carrier is shown in this retained position with the locking projection  302  lodged within the slot  282  in  FIGS. 16, 17, 20, and 21 . 
         [0087]    Referring now to  FIGS. 14, 16 and 17 , an outer shield  306  is shown disposed in a retracted position over the syringe barrel  214  and is provided with a front opening  310  to allow the needle  222  to extend therethrough. The outer shield  306  also includes a rearward extending arm  307  that extends over the outer surface of the syringe body  214  and includes an inclined stop  308   a  and a latching projection  308   b  that are spaced a predetermined distance from each other to define a space therebetween. The latching projection  308   b  is formed of a resilient material and is downwardly deflectable. The rearward extending arm  307  extends through an upstanding collar  309  integral with and extending radially outwardly from the syringe body  214 . Alternatively, the upstanding collar  309  could be designed to be rotatable around the syringe body  214  to allow the rearward extending arm  307  to be adjusted to any location that is desirable. 
         [0088]    Referring now to  FIG. 20 , the syringe device  200  is ready to draw a fluid, e.g., a medicament, into the barrel  214 , via the needle  222 , for example, by retracting the plunger  218 , e.g., in the direction of arrow  301  to the position illustrated in  FIG. 20  in the manner as described above to withdraw a medicament from a vial. Referring now to  FIG. 21 , the contents of syringe barrel  214  may be injected into an injection site  314 , in the manner previously described above by the user placing his fingers  242  on the outwardly extending finger flange  238  and using his thumb  270  on the thumb pad  266  to apply pressure to the plunger  218  to deliver medicament to the injection site  314 . As best shown in  FIGS. 20 and 21 , the plunger  218  will travel through the injection stroke  318  within the syringe barrel  214  until it contacts the needle-carrier  274  and all the medicament has been expelled through the needle  222  into the injection site  314 . 
         [0089]    A driving member, such as an elastic or resilient biasing means, here illustrated as a compression spring  322  of very small diameter and preferably made from stainless steel or other metal, is mounted over the open nozzle  216  of the syringe barrel  214 . Referring now to  FIGS. 16 and 17 , the compression spring  322  is shown in a compressed state therein and is of such a diameter that it also fits within the interior of an outer shield  306  that is disposed over the syringe barrel  214 . The compression spring  322  is provided for urging the outer shield  306  from a retracted position wherein the compression spring  322  is in a compressed state and the hypodermic needle  226  is exposed (e.g.,  FIGS. 20 and 21 ) to a needle-containing position wherein the outer shield  306  extends forwardly to cover the needle  322 , which is best shown in  FIGS. 24 and 25 . 
         [0090]    Referring now to  FIG. 17 , to retain the outer shield  306  in the retracted position, the outer shield  306  includes opposed slots  326  through which opposed deformable members  330  located on the barrel  214  extend. The upright deformable members  330  are integral with the syringe barrel  214  and extend radially outwardly therefrom and through slots  326  to retain the outer shield  306  in the retracted position. The deformable members  330  remain in an upright orientation so long as they are supported by the body of the needle-carrier  274  located thereunder. As best shown in  FIG. 17 , the deformable members  330  remain in an upright position because they are supported by the larger diameter midsection  286  of the needle-carrier. Referring now to  FIGS. 17 and 22  for comparison purposes, as the thumb pad  266  is pressed in the direction of the injection stroke  318  and the plunger  218  is moved distally, it eventually contacts the t-head aft section  294  of the needle-carrier  274 . Referring now to  FIG. 22 , further movement of the plunger  218  in the direction of the injection stroke  318  causes the needle-carrier  274  to move distally within the open nozzle  216  from its retained position to a forward position. As best shown in  FIGS. 22 and 23 , distal movement of the needle-carrier  274  causes the pivotable locking projection  302  to pivot out of the slot  282  of the needle-carrier  274 . 
         [0091]    Referring now to  FIG. 22-25 , as the needle-carrier  274  moves from its retained position to its forward position, the opposed grooves  290  of the needle-carrier  274  move under the deformable members  330 , thus removing support for the deformable members  330  which can no longer remain upright. As a result, the deformable members  330  can no longer engage the outer shield  306  and retain the outer shield in the retracted position. As the compression spring  322  pushes the outer shield  306  to the needle-containing position, the deformable members  330  collapse within the opposed grooves  290  of the needle-carrier  274 .  FIG. 23  illustrates the compression spring  322  beginning to move the outer shield  306  to its needle-containing position as the deformable members  330  have collapsed within the opposed grooves  290 .  FIGS. 24 and 25  illustrate the outer shield moved to the needle-containing position to shield the needle tip  226 . As the outer shield  306  moves to the needle-containing position, the length of the rearward extending arm  307  moves distally through the upstanding collar  309 . As the latching projection  308   b  passes through the collar  309 , it deflects downwardly to pass through the collar  309 . Once the latching projection  308   b  has passed through the collar  309 , it returns to its undeflected position to hold captive the collar  309  in the space located between the inclined stop  308   a  and the latching projection  308   b , thus locking the outer shield  306  in the needle-containing position over the needle  222 . 
         [0092]    Referring now in detail to the various figures of the drawings wherein like reference characters refer to like parts, there is shown at  400  in  FIGS. 26 through 36  a third embodiment safety syringe assembly that includes a syringe barrel  414 , a plunger  418 , and a hypodermic needle  422  having a needle tip  426 . The syringe  400  also includes a removeable protector cap  430  arranged to snap onto the distal end of the safety syrilnge assembly  400 . 
         [0093]    The syringe barrel  414  defines a reservoir within which a fluid, e.g., a medicament, may be contained and dispensed therefrom. The barrel  414  has an outwardly extending flange  438  located towards the proximal end of the barrel  414  which facilitates gripping of the barrel with the user&#39;s fingers  442  ( FIG. 26 ) when it is desired to move the plunger  418  relative to the barrel  414  linearly for normal use, such as when moving the plunger  418  through an injection stroke indicated at arrow  417  ( FIG. 33 ) to inject a fluid, e.g., a medicament into a patient. The finger flange  438  may be annular or oblong (as shown). The portion of the syringe barrel  414  forward of the finger flange  438  is substantially transparent and includes volume measuring indicia  440  ( FIGS. 26 and 27 ) on the surface thereof to enable a user to determine the volume of fluid within the barrel  414 . Referring now to  FIGS. 27 and 29 , disposed within the distal opening  416  of the syringe barrel  414  is a reduced diameter internal nozzle  415 , the internal nozzle being tapered distally and integral with the syringe barrel  414 . As best shown in  FIG. 29 , the internal nozzle  415  includes a central opening  428  that extends axially and is in fluid communication with the reservoir of the syringe barrel  414 . 
         [0094]    Referring again to  FIGS. 27 and 29 , a needle-carrier  474  is disposed over the internal nozzle  415  at the distal end of the syringe barrel  414  and may be secured to the distal end by any suitable means, e.g., threads disposed on the internal surface of the distal opening  416 . The needle-carrier  474  comprises a generally tapered tubular body including ribs  475  ( FIG. 27 ) and includes an axially extending through-hole provided at its center for securing the hypodermic needle  422  therethrough. As best shown in  FIGS. 27, 29 and 35 , the needle-carrier  474  includes a support surface  478  for supporting a driving member, such as an elastic or resilient biasing means, here illustrated as a compression spring  490  of very small diameter and preferably made from stainless steel or other metal. For example, the compression spring  490  may be of frusto-conical shape having a wider end supported by the support surface  478  and a narrower end supported by an inner-step or support surface  431   a  provided on the interior surface of the outer shield  431  ( FIG. 35 ). The needle-carrier  474  also includes a pair of radially extending projections  476  arranged for retaining the outer shield  431  thereover in the manner discussed below. 
         [0095]    Referring again to  FIGS. 27 and 29 , the outer shield  431  is arranged to be disposed over the needle-carrier  474  and compression spring  490  and retained thereover in an engaged position. To this end, the outer shield  431  is provided with a pair of opposed and outwardly flaring wings  433 , each wing including a through-slot  435  at a base portion thereof. The through-slot  435  is sized and located to allow passage of the opposed radially extending projections  476  of the needle-carrier  474  therethrough to retain the outer shield  431  in an engaged position over the needle-carrier  474  and compression spring  490 . When the outer shield  431  is in the engaged position, the compression spring is in a compressed state and the hypodermic needle  422  extends through a central opening  496  in the outer shield  431  thus exposing the needle  422  for drawing fluids into the syringe barrel and expelling fluids through the needle  422  at an injection site. Upon release of the outer shield  431  from the engaged position (described in detail below), the compressed spring  490  extends to its normal position and drives the outer shield  431  to a needle-containing position, as best shown in  FIGS. 35-36 . 
         [0096]    A release ring  419  is provided to fit snugly over the distal end of the syringe  414  and includes a plurality of radially inward extending tabs  421 . The inwardly extending tabs  421  are arranged to extend into elongated slots  423  also located at the distal end of the syringe barrel  414 . The slots  423  are somewhat elongated in length so that when the tabs  421  are disposed therein, the release ring  419  is slideable in an axial direction a short predetermined distance over the syringe barrel  414  between a retained position and a releasing position. As best shown in  FIG. 29 , when in the retained position, the inwardly extending tabs  421  of the release ring  419  are positioned at the proximal end of the slots  423 . As best shown in  FIGS. 34-36 , when in releasing position, the inwardly extending tabs  421  of the release ring  419  are positioned at the distal end of the slots  423 . The release ring  419  is provided with an annular release projection  425  that includes a forward facing annular ramp  427  (best seen in  FIGS. 35 and 36 ). When the release ring  419  is in the retained position, the annular ramp  427  is arranged to abut the outwardly flaring wings  433  of the outer shield  431 . When the release ring  419  is slid axially to the releasing position, the annular ramp  427  engages the wings  433  outwardly releasing them from the extending projections  476  thus causing the outer shield  431  to spring to a needle-enclosing position. 
         [0097]    The plunger  418  extends within the open rear end of the syringe barrel  414  and includes a first end with a stopper  462  positioned within the reservoir of the syringe barrel  414 . The stopper  462  is adapted to provide a slidable seal with the interior surface of the syringe barrel  414  for expelling fluids through the distal end of the syringe barrel  414 . The stopper  462  is in fluid tight engagement with the interior surface of the syringe barrel  414 . The stopper  462  is preferably made of suitable materials as described in connection with the earlier embodiments, and may be substantially non-compressible. A second end of the plunger  418  extending out of the open rear end of the syringe barrel  414  includes a thumb pad  466  or thumb press area for receiving delivery pressure for pressing the plunger into the syringe barrel  414  to deliver the fluid, e.g., medicament. The thumb press  466  may be depressed by the thumb  470  ( FIG. 26 ) or finger  442  of a user during use of the syringe device. As shown in the figures, the diameter of the stopper  462  is approximately equal to the inside diameter of the syringe barrel  414  extending rearwardly therefrom. 
         [0098]    Referring now to  FIG. 32 , the syringe device  400  is ready to draw a fluid, e.g., a medicament, into the barrel  414 , via the needle  422  from a vial  403 , for example, by retracting the plunger  418 , e.g., in the direction of arrow  401  to the position illustrated in  FIG. 32  in the manner as described in earlier embodiments to withdraw a medicament from the vial  403 . Referring now to  FIG. 33 , once the fluid is drawn into the syringe barrel  414 , the contents of the syringe barrel  414  may be injected into an injection site such as any subcutaneous or intra-muscular location on a person where an injection is needed. 
         [0099]    The contents of syringe barrel  414  is injected in the manner previously described by the user placing his fingers  442  on the outwardly extending finger flange  438  and using his thumb  470  on the thumb pad  466  to apply pressure to the plunger  418  to deliver medicament to the injection site. As best shown in  FIGS. 29, 33 and 34 , as the plunger  418  travels through the injection stroke (arrow  417 ), within the syringe barrel  414  the plunger stopper  462  eventually abuts and exerts pressure in the distal direction upon a seal  508  located within the syringe barrel  414 . The seal  508  may include an annular groove, is generally cylindrical, and provides a watertight fit with the interior surface of the syringe barrel  414 . In turn, the seal  508  exerts force against the inwardly extending tabs  421  of the release ring  419  to push the release ring  419  within the slot  423  of the syringe barrel  414  from the proximal side to the distal side of the slot  423 . 
         [0100]    As the release ring  419  moves distally, its forward facing annular ramp  427  applies force to the outwardly flared wings  433  of the outer shield  431  driving the wings  433  radially outward and eventually lifting the wings  433  above the radially extending projections  476  of the needle-carrier  474 . Referring now to  FIGS. 35 and 36 , once the wings  433  have cleared the tops of the projections  476 , the outer shield  431  is no longer engaged by the projections  476  of the needle-carrier  474 . As a result, as best shown in  FIGS. 35 and 36 , the compressed spring  490  expands to its normal position and drives the outer shield  431  to a needle-containing position. As the outer shield  431  moves to the needle-containing position, the central opening  496  will travel distally over the needle  422  and beyond the needle tip  426  to safely contain the needle within the outer shield  431 . 
         [0101]    Referring now to  FIGS. 27, 35 and 36 , a limit ring  500  is shown. In  FIGS. 35 and 36 , the limit ring  500  is shown mounted in abutting relation with a stepped portion of the outer shield  431 . As can best be seen in  FIG. 27 , the limit ring  500  is provided with a proximally extending finger  512  that is arranged to extend within a slot  516  in the outer shield  431  to assure the snug mounting of the limit ring  500  over the shield  431 . The limit ring  500  also includes a laterally extending tab  502  that is connected to a tether  520  which connects the limit ring  500  to the needle-carrier  474  (best seen in  FIG. 36 ), the tether  520  being of a pre-selected length. The tether  520  may be of a construction that includes multiple hinges enabling it to fold and unfold therealong. Alternatively, a tether  524  may be formed of a bendable material. As the outer shield  431  moves from the engaged position to the needle-containing position, the tethered limit ring  500  will limit movement of the outer shield  431 . In other words, the limit ring  500  will prevent the outer shield  431  from moving beyond the needle tip  426  and assure that the entire needle  422  including the tip will be contained within the outer shield  431  so as to prevent exposure to a contaminated needle. As best shown in  FIG. 36 , when moved to the needle-containing position, the outer shield  431  is in an off-set position with respect to the needle tip  426 . This is due to the fact that the spring  490  is mounted over the needle-carrier  474  in a slightly offset position due to the inclusion of the support surface  478  ( FIG. 35 ) which does not extend radially around the entire needle-carrier  474 . In this manner, the needle tip  426  is offset from the central opening  496  of the outer shield  431  to prevent inadvertent contact with the contaminated needle. 
         [0102]    Referring now in detail to the various figures of the drawings wherein like reference characters refer to like parts, there is shown at  600  in  FIGS. 37 through 47A  a fourth embodiment safety syringe assembly that includes a syringe barrel  614 , a plunger  618 , and a hypodermic needle  622  having a needle tip  626 . The syringe assembly  600  includes a needle protector cap  624  ( FIG. 38 ) arranged to snap onto the distal end of the safety syringe assembly  600  to protect the needle prior to use. The deployable outer shield  630  is arranged to move in response to thumb actuation from a retracted position (best shown in  FIGS. 37, 39, 40, 43, and 44 ) to a needle-protecting position (best shown in  FIG. 47 ). As best shown in  FIGS. 37 and 39 , the surfaces of the outer shield  630  include a raised or thickened portion arranged to be disposed over the indicia  643  of the syringe  614 . This raised or thickened portion extends over the length of the volume measuring indicia  643  and provides magnification to ease reading of said indicia  643 . 
         [0103]    As best shown in  FIG. 40 , the syringe barrel  614  includes a forward end nozzle  616  having a reduced diameter axial opening in which the needle  622  is mounted, and a rear end including a reservoir  632  ( FIG. 43 ) within which a fluid, e.g., a medicament, may be contained. The needle  622  or needle cannula (those terms being used interchangeably herein) includes a forward tip  626  and is in fluid communication with the reservoir  632  through the reduced diameter nozzle  616 . 
         [0104]    As best seen in  FIG. 38 , the syringe barrel  614  includes an outwardly extending flange  638  located towards the proximal end of the barrel  614  which facilitates gripping of the barrel  614  with the user&#39;s fingers  642  ( FIG. 37 ) when it is desired to move the plunger  618  relative to the barrel  614  linearly for normal use, such as when moving the plunger  618  through an injection stroke to inject a fluid, e.g., a medicament into a patient. The finger flange  638  may be annular or oblong. The finger flange  638  is provided with upstanding ears  644 . Together, the finger flange  638  and upstanding ears  644  are provided to enable the user to position and retain the barrel  614  within fingers  642  ( FIG. 37 ) while using the thumb  677  to move the plunger  618  through the injection stroke. Upon completion of the injection stroke, if it is desired to deploy the outer shield  630  to the needle-protecting position, the user moves the thumb  677  from the thumb pad  674  of the plunger  618  and depresses an actuation member  702  located in close proximity to the thumb pad  674 . Due to the close proximity between the thumb pad  674  and the actuation member  702 , movement of the thumb  677  from the plunger thumb pad  674  to the actuation member  702  is an easy transition. Also, this proximity between the thumb pad  674  and the actuation member  702  eliminates the need for the user to reposition fingers  642  on the finger flange  638  or on any other part of the embodiment during this transition, thus enabling the user to maintain the syringe barrel  614  in a relatively safe position during this transition to avoid accidental needle tip pricks after withdrawal from patients. 
         [0105]    The portion of the syringe barrel  614  forward of the finger flange  638  is substantially transparent and includes volume measuring indicia  643  ( FIG. 38 ) on the surface thereof to enable a user to determine the volume of fluid within the barrel  614 . For example, the syringe barrel  614  may hold up to 3.0 ml in volume, however, may hold other volumes greater or lesser. As best shown in  FIG. 38 , the syringe barrel  614  includes a cylindrical wall  646  that extends rearward from the finger flange  638  and is somewhat larger in diameter than the forward portion of the syringe barrel  614  and includes a slot  650  bounded by the cylindrical wall  646 . As best shown in  FIGS. 38 and 39 , an upper catch  658  is located on the top side of the syringe barrel  614  and includes an inclined surface that faces towards the syringe barrel proximal end while a lower catch  662  located on the bottom side of the syringe barrel  614  includes an inclined surface that faces towards the syringe barrel distal end. The upper catch  658  is arranged for engaging a forward extending deflectable member  666  and a rearward extending deflectable member  670 , both members being resiliently deflectable and located on the top surface of the deployable outer shield  630 . The lower catch  662  is situated within an elongated slot  672  located on the bottom portion of the outer shield  630 . The elongated slot  672  is bounded by a peripheral wall including an end wall  673  that serves as a stop to limit movement of the outer shield  630  beyond a needle-containing position. 
         [0106]    The plunger  618  extends within the open rear end of the syringe barrel  614  and includes a first end with a stopper  654  positioned within the reservoir of the syringe barrel  614 . The stopper  654  is preferably substantially non-compressible. A second end of the plunger  618  extending out of the open rear end of the syringe barrel  614  includes a thumb pad  674  or thumb press area for receiving delivery pressure for pressing the plunger into the syringe barrel to deliver the fluid, e.g., medicament. The terms “thumb pad” and “thumb press area” are used interchangeably herein and designate a region coupled to or otherwise formed on an end of the plunger and which may be depressed by the thumb  677  or finger of a user during use of the medical device. 
         [0107]    Referring now to  FIGS. 37, 39 and 40 , the safety syringe assembly  600  is shown therein generally in a condition in which it is ready for use. That is, in these figures, it can be seen that the hypodermic needle  622  is in an exposed state where it can be protected by the cap  624 , and the plunger  618  is in an advanced position within the syringe barrel  614 . The outer shield  630  is disposed in the retracted position over the syringe barrel  614 . Referring now to  FIG. 43 , the outer shield  630  is provided with a front opening  678  to allow the needle  622  to extend therethrough. The syringe  600  is ready to draw a fluid, e.g., a medicament, into the barrel  614 , via the needle  622 , for example, by retracting the plunger  618 , e.g., in the direction of arrow  682  to the position illustrated in  FIG. 43 . 
         [0108]    The syringe assembly may be pre-filled with a fluid, e.g., a medicament. Alternatively, as shown in  FIG. 43 , the fluid may be withdrawn from a storage vial  686  having a membrane  690  sealed to the upper end thereof. That is, the vial  686  containing the fluid is inverted and the tip  626  of the needle  622  is pierced through the membrane  690 . The fluid, e.g., the medicament, is withdrawn from the vial into the syringe barrel  614  by moving the plunger  618  in the direction of arrow  682  in  FIG. 43 . Thereafter, once a designated amount of fluid is withdrawn into the syringe barrel  614 , the needle may be removed from the vial and the syringe device is ready for use on a patient. Referring now to  FIG. 44 , the contents of syringe barrel  614  may be injected into an injection site  694 , such as any subcutaneous or intra-muscular location on a person where an injection is needed. The user causes needle  622  to pierce the skin above the injection site  694 . The user places his fingers  642  on the outwardly extending finger flanges  638  and using his thumb  677  on the thumb pad  674  applies pressure to press the plunger  618  into the syringe barrel  614  along an injection stroke indicated by arrow  698  to expel the fluid, e.g., medicament through the needle  622  and deliver the fluid into the injection site  694  of the person. As best shown in  FIG. 44 , the plunger  618  will travel through the injection stroke within the syringe barrel  614  until it reaches a terminus within the syringe barrel  614  at which point it can travel no further and all of the medicament has been expelled through the needle  622  into the injection site  694 . 
         [0109]    The outer shield  630  is provided with an upwardly extending actuation member  702  which is provided for urging the outer shield  630  from the retracted position wherein the hypodermic needle  626  is exposed ( FIG. 45 ) to a needle-containing position wherein the outer shield  630  extends forwardly to cover the needle  622 , which is best shown in  FIGS. 46 and 47 . Referring now to  FIG. 40 , the outer shield  630  is shown retained in the retracted position as a result of the rounded surface of the forward extending deflectable member  666  of the outer shield  630  abutting the upper catch  658  of the syringe barrel  614 . Once the plunger  618  has reached the terminus of the injection stroke, the user may deploy the outer shield  630 . As mentioned above, upon completion of the injection stroke, if it is desired to deploy the outer shield  630  to the needle-protecting position, the user may readily move the thumb  677  from the thumb pad  674  of the plunger  618  to the actuation member  702  located in close proximity thereto. During this transition, the user can maintain the barrel  614  in a relatively safe orientation by keeping fingers  642  placed on the finger flanges  638 . 
         [0110]    Referring now to  FIGS. 45-47 , as thumb pressure is applied to the actuation member  702 , the deflectable member  666  deflects outwardly as the rounded forward surface rides up and eventually clears the top surface of the upper catch  658 . After the rounded forward surface of the deflectable member  666  has passed the upper catch  658 , the deflectable member  666  returns to its undeflected position, thus permitting the outer shield  630  to be moved by thumb pressure to the needle-containing position. As the outer shield  630  is moved towards the needle-containing position, the inclined surface of the rear extending deflectable member  670  rides up and eventually clears the top surface of the upper catch  658 . Once the deflectable member  670  has cleared the upper catch  658 , it returns to its undeflected position and the lower catch  662  abuts the end wall  673  to lock the outer shield  630  in place in the needle-containing position to prevent inadvertent contact with the contaminated needle. 
         [0111]    As best shown in  FIGS. 38A, 39A, and 47A , alternatively, a compression spring  675  may be positioned in a compressed state between the front end of the syringe barrel  614  and the outer shield  630  when the outer shield is in the retracted position. As best shown in  FIG. 38A , the compression spring  675  is sized in diameter to fit over a reduced diameter nozzle  677  located at the distal end of the syringe barrel  614 . As thumb pressure is applied to the upwardly extending actuation member  702 , the forward extending deflectable member  666  rides up and eventually clears the top surface of the upper catch  658 . As the deflectable member  666  clears the top surface of the upper catch  658 , the compressed spring  675  moves to its normal position, and propels the outer shield  630  from its retracted position to its deployed to lock the outer shield  630  in the needle-containing position as described above. 
         [0112]    Referring now in detail to the various figures of the drawings wherein like reference characters refer to like parts, there is shown at  800  in  FIGS. 48 through 53  a fifth embodiment safety syringe assembly that includes a syringe barrel  814 , a plunger  818 , and a hypodermic needle  822  having a needle tip  826 . The syringe  800  also includes a removeable needle protector cap  830  ( FIGS. 48, 49 ) arranged to snap onto the distal end of the safety syringe assembly  800  to protect against needle pricks when the outer shield  806  is in a retracted position. 
         [0113]    The syringe barrel  814  defines a reservoir within which a fluid, e.g., a medicament, may be contained and dispensed therefrom. The barrel  814  has an outwardly extending flange  838  located towards the proximal end of the barrel  814  which facilitates gripping of the barrel with the user&#39;s fingers  842  ( FIG. 48 ) when it is desired to move the plunger  818  relative to the barrel  814  linearly for normal use, such as when moving the plunger  818  through an injection stroke to inject a fluid, e.g., a medicament into a patient. The finger flange  838  may be annular or oblong. The portion of the syringe barrel  814  forward of the finger flange  838  is substantially transparent and includes volume measuring indicia  840  ( FIG. 49 ) on the surface thereof to enable a user to determine the volume of fluid within the barrel  814 . Referring now to  FIGS. 49, 50 and 51 , a needle-carrier  874  is positioned within the barrel  814  at the distal end thereof. 
         [0114]    The needle-carrier  874  is positioned within the barrel  814  at its open distal end  816 . As best seen in  FIGS. 48-49 , as the syringe barrel  814  extends in the proximal direction from the finger flange  838 , it is slightly larger in diameter at  817  than the barrel  814  extending forward from the finger flange  838 . 
         [0115]    The plunger  818  extends within the open rear end of the syringe barrel  814  and includes a first end with a stopper  862  positioned within the reservoir of the syringe barrel  814 . The stopper  862  is adapted to provide a slidable seal with the interior surface of the syringe barrel for expelling fluids through the distal end of the syringe barrel  814 . The stopper  862  is in fluid tight engagement with the interior surface. Preferably, the stopper  862  is substantially non-compressible. The proximal end of the plunger  818  includes a thumb pad  866  for receiving delivery pressure for pressing the plunger into the syringe barrel to deliver the fluid, e.g., medicament. The thumb pad  866  may be depressed by the thumb  870  ( FIG. 48 ) or finger of a user during use of the syringe device. 
         [0116]    Referring now to  FIGS. 49 through 51 , the hypodermic needle  822  is held within the needle-carrier  874 . The needle-carrier  874  comprises a body having a through hole  815  provided at its center for securing the hypodermic needle  822  therein. The needle-carrier  874  includes a fore section  878  having generally square outer surface ( FIG. 49 ), a mid-section  886  on which a pair of opposed wings  890  are provided, and an aft section  894  in the form of a “t-head”. The t-head includes an annular groove over which a generally cylindrical seal  898  may be positioned and retained. The seal  898 , formed of a suitable biocompatible material, is adapted to provide a watertight fit with the interior surface of the syringe barrel  814  so that fluid in the barrel reservoir is directed into the needle  822  for delivery to the injection site of the person. 
         [0117]    As best shown in  FIG. 50 , the wings  890  are biased towards a deployed position. In this position, the wings retain the outer shield  806  in a retracted position over the distal end of the syringe barrel  814 , thus exposing the needle  822 . Referring now to  FIGS. 50 through 52 , the wings  890  are arranged to move from the deployed position ( FIG. 50 ) to a collapsed position ( FIG. 52 ) thus enabling the outer shield  806  to move from its retracted position to an extended position in a manner to be discussed in more detail below. 
         [0118]    A driving member, such as an elastic or resilient biasing means, here illustrated as a compression spring  823  of very small diameter and preferably made from stainless steel or other metal, is mounted over a shoulder  875  of the syringe barrel  814 , as best shown in  FIG. 50 . In  FIG. 50 , the compression spring  823  is shown in a compressed state and is of such a diameter that it fits within the interior of the outer shield  806  and is disposed over the syringe barrel shoulder  875 . The compression spring  823  is provided for urging the outer shield  806  from the retracted position wherein the compression spring  823  is in a compressed state and the hypodermic needle  822  is exposed to a needle-containing position wherein the outer shield  806  extends forwardly to cover the needle  822 , which is best shown in  FIG. 52 . 
         [0119]    Referring again to  FIG. 50 , the outer shield  806  is shown disposed in a retracted position over the syringe barrel  814 . The outer shield  806  also includes a rearward extending arm  807  that extends over the outer surface of the syringe body  814  and includes an inclined stop  808   a  and a latching projection  808   b  that are spaced a predetermined distance from each other to define a space therebetween. The latching projection  808   b  is formed of a resilient material and is downwardly deflectable. The rearward extending arm  807  extends through an upstanding collar  809  integral with and extending radially outwardly from the syringe body  814 . 
         [0120]    Referring again to  FIG. 50 , the syringe device  800  is ready to draw a fluid, e.g., a medicament, into the barrel  814 , via the needle  822 , for example, by retracting the plunger  818 , e.g., in the direction of arrow labeled “FILL”  801  to withdraw a medicament from a vial. The contents of syringe barrel  814  may be injected into an injection site (not shown) in the manner previously described by the user placing fingers  842  on the outwardly extending finger flange  838  and using the thumb  870  on the thumb pad  866  to apply pressure to the plunger  818  to deliver medicament in the direction of the arrow labeled “INSERT”  803  to the injection site (not shown). Referring to  FIGS. 50 and 51 , the plunger  818  will travel through the injection stroke  803  within the syringe barrel  814  until it contacts the aft section  894  of the needle-carrier  874  and all the medicament has been expelled through the needle  822  into the injection site. 
         [0121]    As best shown in  FIGS. 49 and 50 , the syringe barrel  814  is provided with opposed slots  827  through which the wings  890  may extend. Likewise, the outer shield  806  is provided with opposed slots  829  that align with the syringe barrel slots  827  when the outer shield  806  is in the retracted position. In this manner, the wings  890  may extend through the slots  827  and  829  to retain the outer shield  806  in the retracted position over the syringe barrel  814  and retain the compression spring  823  in a compressed state. Referring now to  FIG. 51  for comparison purposes, as the thumb pad  866  is pressed in the direction of the injection stroke  803  and the plunger  818  is moved distally, it eventually contacts the aft section  894  of the needle-carrier  874 . Further movement of the plunger  818  in the direction of the injection stroke  803  causes the needle-carrier  874  to move slightly in a distal direction within the distal open end  816  of the barrel  814 . Such distal movement of the needle-carrier  874  causes the wings  890  to move from their deployed position to their collapsed position. 
         [0122]    Referring now to  FIGS. 51 and 52 , as the needle-carrier  874  moves distally within the syringe barrel  814 , the wings  890  move from their deployed position to the collapsed position, and out of engagement with the outer shield  806 . Once the outer shield  806  becomes disengaged from the wings  890 , the compression spring  823  pushes the outer shield  806  to the needle-containing position ( FIG. 52 ).  FIG. 51  illustrates the compression spring  822  beginning to move the outer shield  806  to its needle-containing position as the wings move to their collapsed position. As the outer shield  806  moves to the needle-containing position, the length of the rearward extending arm  807  moves distally through the upstanding collar  809 . As the latching projection  808   b  passes through the collar  809 , it deflects downwardly to pass through the collar  809 . Once the latching projection  808   b  has passed through the collar  809 , it returns to its undeflected position to prevent movement of the outer shield in the proximal direction away from the needle-containing position. Further movement of the outer shield  806  in the distal direction past the needle containing position is prevented due to the inclined stop  808   a  abutting the collar  809 . Thus, the collar  809  is held captive in the space located between the inclined stop  808   a  and the latching projection  808   b , thus locking the outer shield  806  in the needle-containing position over the needle  822 . 
         [0123]    As described above, once the outer shield  806  moves to the needle-containing position, further movement in either the distal or the proximal direction is substantially limited due to the collar  809  being held captive in the space located between the inclined stop  808   a  and the latching projection  808   b  of the shield  806 . However, it should be understood that use of these components for limiting movement of the outer shield  806  in this manner is merely exemplary, and alternative components could be substituted. For example, the limit ring  500  and tether  520 , as described in connection with the third embodiment above, could be utilized in this fifth embodiment as substitute components for accomplishing the same function of substantially limiting movement of the outer shield  806  once it has reached the needle-containing position. That is, the ring  500  of the third embodiment could be disposed over the shield  806  of this fifth embodiment and connected to the syringe barrel  814  by the tether  520  in a manner similar to that described under the third embodiment. Likewise, the limit ring  500  and tether  520 , as described in connection with the third embodiment above, could be utilized in the second embodiment as substitute components for the upstanding collar  309 , and the rearward extending arm  307 , the inclined stop  308   a  and the downwardly deflectable latching projection  308   b , to limit movement of the shield  306  past the needle-containing position. 
         [0124]    Likewise, under the third embodiment described above, the limit ring  500  and tether  52  are utilized for substantially limiting movement of the outer shield  431  once it has reached the needle-containing position. It should be understood that these components are merely exemplary and alternative components could be utilized for accomplishing this function. For example, this function could be accomplished in the third embodiment utilizing components employed in the second and fifth embodiments, i.e., the collar  809  disposed on the syringe barrel  814  being held captive in the space located between the inclined stop  808   a  and the latching projection  808   b  of the shield  806 . 
         [0125]    Referring now in detail to the various figures of the drawings wherein like reference characters refer to like parts, there is shown at  900  in  FIGS. 54 through 61  a sixth embodiment safety syringe assembly that includes a syringe barrel  914  that is substantially transparent and includes volume measuring indicia  916  on the surface thereof to enable a user to determine the volume of fluid within the barrel  914 . The syringe assembly  900  also includes a plunger  918 , and a hypodermic needle  922  having a needle tip  926 . The syringe assembly  900  includes a needle protector cap  924  ( FIG. 56 ) arranged to snap onto the distal end  931  of the safety syringe assembly  900  to protect the needle prior to use. The deployable outer shield  930  is arranged to move in response to thumb actuation from this retracted position, for example as shown in  FIG. 57 , to a needle-containing position (best shown in  FIG. 61 ). 
         [0126]    As best shown in  FIG. 56 , the syringe barrel  914  includes a forward end nozzle  923  having a reduced diameter, an axial opening  919  in which the needle  922  is mounted, and a central reservoir  932  ( FIG. 59 ) within which a fluid, e.g., a medicament, may be contained. The needle  922  or needle cannula (those terms being used interchangeably herein) includes a forward tip  926  and is in fluid communication with the reservoir  932  through the reduced diameter nozzle  923 . As best shown in  FIGS. 56, 57 and 60 , an upper catch  958  is located on the top side of the syringe barrel  914  and includes an inclined surface that faces towards the syringe barrel proximal end. 
         [0127]    As shown in  FIGS. 57 and 60 , a compression spring  959  is shown in a compressed state between the front end of the syringe barrel  914  and the outer shield  930  when the outer shield is in the retracted position. The compression spring  959  is sized in diameter to fit over a reduced diameter nozzle  923  located at the distal end of the syringe barrel  914 . 
         [0128]    As best seen in  FIGS. 54 through 56 , the syringe barrel  914  includes an outwardly extending flange  938  located towards the proximal end of the barrel  914  which facilitates gripping of the barrel  914  with the user&#39;s fingers  942  (shown in phantom in  FIGS. 57 and 60 ) when it is desired to move the plunger  918  relative to the barrel  914  linearly for normal use, such as when moving the plunger  918  through an injection stroke to inject a fluid, e.g., a medicament into a patient. In  FIG. 57 , the plunger  918  is illustrated as positioned at the terminal end of the central reservoir  932  of the syringe barrel  914 . When in this terminus position, either the syringe assembly  900  is ready for loading of a medicament within the syringe barrel  914 , also known as the ready position, or the plunger  918  has completed its travel through the injection stroke to deliver a medicament from the central reservoir  932  through the needle  922 , and into a patient. As best illustrated in  FIG. 59 , when it is desired to load a medicament into the syringe barrel  914 , such as from a vial, the plunger  918  may be withdrawn from the terminus position in a loading direction as indicated by arrow  921 . As illustrated in  FIG. 59 , during loading of the medicament into the syringe barrel  914 , the plunger  918  is pulled back within the central reservoir  932  so that the actuator  917  is forward of the thumb pad  974 . 
         [0129]    The finger flange  938  may be annular or oblong. Optionally, the finger flange  938  may be provided with upstanding ears  944 . Together, the finger flange  938  and the upstanding ears  944  enable the user to position and retain the barrel  914  within fingers  942  ( FIG. 57 ) while using the thumb  977  to move the plunger  918  through the injection stroke. As best shown in  FIGS. 55, 57, and 59 , the syringe barrel  914  includes a cylindrical wall  946  that extends rearward from the finger flange  938  and is somewhat larger in diameter than the forward portion of the syringe barrel  914  and includes a slot  950  bounded by the cylindrical wall  946 . 
         [0130]    The plunger  918  extends within the open rear end of the syringe barrel  914  and includes a first end with a stopper  954  positioned within the reservoir of the syringe barrel  914 . The stopper  954  is preferably substantially non-compressible. A second end of the plunger  918  extending out of the open rear end of the syringe barrel  914  includes a thumb pad  974  or thumb press area for receiving delivery pressure from a user&#39;s thumb  977  for pressing the plunger into the syringe barrel to deliver the fluid, e.g., medicament. 
         [0131]    Referring now to  FIGS. 54 through 57 , the outer shield  930  is shown arranged disposed over the syringe barrel  914  in the retracted position wherein the distal end  931  of the shield  930  is disposed over the forward end nozzle  923  of the syringe barrel  914 . The distal end  931  of the outer shield  930  includes a central opening  931   a  to enable passage of the needle  922  therethrough when the outer shield is in the retracted position. The outer shield also includes a ring  915  arranged to surround the syringe barrel  914  and retain the outer shield  930  thereover. The outer shield  930  is provided with an elongated section  933  that is disposed over a portion of the syringe barrel  914  and is situated opposite the volume measuring indicia  916  so as to not interfere with a user reading said indicia  916 . The outer shield  930  also includes an arcuate shaped actuator  917  disposed at the proximal end thereof. Referring again to  FIGS. 56, 57 and 60 , the upper catch  958  located on the top side of the syringe barrel  914  is arranged for engaging a distally extending deflectable member  966  and a proximally extending deflectable member  970 , both members being resiliently deflectable and integral with the deployable outer shield  930 . 
         [0132]    Referring now to  FIG. 57 , the plunger  918  is illustrated as having reached the terminus of the injection stroke which is a position that is slightly forward of the position of the actuator  917 . Thereafter, if it is desired to deploy the outer shield  930  to the extended needle-containing position, the thumb  977  may be repositioned from the thumb pad  974  to the actuation member  917  of the shield  930 . Due to the arcuate shape of the actuation member  917  and the close proximity between the thumb pad  974  and the actuation member  917 , movement of the thumb  977  from the thumb pad  974  to the actuation member  917  is an easy transition. For example, the thumb  977  may be easily rolled from the thumb pad  974  to the actuation member  917 . Also, this proximity between the thumb pad  974  and the actuation member  917  eliminates the need for the user to reposition fingers  942  on the finger flange  938  or on any other part of the embodiment 900 during this transition, thus enabling the user to maintain the syringe barrel  914  in a relatively safe position during this transition to avoid accidental needle tip pricks. 
         [0133]    As thumb pressure is applied to the arcuate actuation member  917  to move the actuation member  917  forward, the forward extending deflectable member  966  deflects upwardly as its rounded forward surface rides up and eventually clears the top surface of the upper catch  958 . As the forward extending deflectable member  966  clears the top surface of the upper catch  958 , the compressed spring  959  moves from its compressed state towards its uncompressed position, and propels the outer shield  930  to move from its retracted position to its deployed needle-containing position. As best shown in  FIG. 61 , as the shield  930  continues to move distally towards the needle-containing position, proximally extending deflectable member  970  rides up and over the catch  958 . Once the deflectable tab  970  has cleared the upper catch  958 , it serves as a stop to prevent movement of the outer shield in the direction of the retracted position to prevent inadvertent contact with a possibly contaminated needle. Simultaneously, as the actuation member  917  moves distally, it eventually reaches finger flange  938  which stops further movement of the outer shield  930  in the distal direction. It should be understood that under the present embodiment, the compression spring  959  is optional. In other words, the compression spring  959  could be omitted and the outer shield  930  could be moved from its retracted position to its deployed needle-containing position in response to manual actuation, e.g., moving the outer shield  930  by thumb pressure. 
         [0134]    As an alternative to deploying the outer shield  930  after the plunger  918  has traveled to its terminus within the central reservoir  932 , the thumb may be used to depress the actuator member  917  and the thumb press  974  simultaneously to deploy the outer shield  930  as the plunger  918  approaches its terminus within the reservoir  932 . Referring now to  FIG. 60 , the plunger  918  is shown as approaching the terminus of its injection stroke, with some medicament remaining within the central reservoir  932  of the syringe barrel  914 , as indicated at  939 . In  FIG. 60 , the thumb  977  is shown depressing the thumb press  974  and the actuation member  917  at the same time. Further simultaneous depression of these two components will cause the plunger  918  to reach its terminus within the reservoir  932 , while causing the spring  959  to propel the outer shield  930  from its retracted position to its needle-containing position, in the manner previously described. In this manner, the operator is provided with freedom-of-choice to decide whether to deploy the shield during the injection of the medicament, or after the injection of medicament has been completed. 
         [0135]    While various embodiments have been shown and described, various modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustrations and not limitation.