Abstract:
A safety needle assembly having a rigid housing that encloses a locking mechanism, an actuator that is operable to slide a sheath over the tip of the needle to prevent accidental sticks after the needle has been used, and an actuator that is operable in response to the final end movement of the syringe plunger to effect movement of the actuator over the needle tip. The housing is made in a standard size that is mountable on a connection port formed on a syringe barrel that can have a much greater diameter than the connection port. An adapter is provided for mounting a standard needle having a Luer lock to enable a health care professional the flexibility to use conventional needles to load medicine into the syringe barrel then replacing with a safety needle assembly for injection of the medicine.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims domestic priority on U.S. Provisional Patent Application Ser. No. 60/688,938, filed Jun. 9, 2005, and on U.S. Provisional Patent Application Ser. No. 60/717,085, filed Sep. 14, 2005, the contents of both provisional applications being incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention relates generally to hypodermic syringes for injecting medicine into patients, and, more particularly, to a needle assembly that can be used with multiple sizes of syringe barrels.  
       BACKGROUND OF THE INVENTION  
       [0003]     Safety syringes are known in the art, such as depicted in U.S. Pat. No. 5,720,727, issued to Gary Alexander on Feb. 24, 1998, the sheath is advanced by operation of the plunger. While such a configuration provides an excellent protection for health care workers from accidental needle sticks, the mechanism does not prevent intravenous drug users from overriding the safety features and re-using the needle for illicit drug purposes, exposing the user to risks associated with contaminated needles. Most known locking mechanisms are designed to secure the syringe in an exposed condition. Such locking mechanisms are not designed to prevent a determined drug user from overriding the locking mechanism to permit the plunger to be retracted from the barrel in order to re-use the needle.  
         [0004]     An improvement in the locking mechanism for a safety needle can be found in Applicant&#39;s U.S. Pat. No. 6,626,863, granted Sep. 30, 2003. In this configuration, the needle is housed within a tubular sheath that is movable between an exposed position, in which the point of the needle is extended beyond the sheath for utilization, and a covered position, in which the point is withdrawn into the sheath. The movement of the sheath is actuated by engagement with the syringe plunger that moves a locking mechanism into a position that slides the sheath over the needle. The barrel of the syringe can also incorporate an additional locking mechanism that prevents the plunger from being retracted out of the barrel, and thus perhaps exposing the needle from the sheath.  
         [0005]     Safety syringes incorporating the aspects of the &#39;863 patent have been available commercially and are provided as an integral unit, including the barrel, plunger, needle, sheath and locking mechanism. Once used, the safety syringe cannot be re-used. Furthermore, since the needle cannot be removed from the syringe barrel, the size or gauge of needle is not variable with respect to the size of the barrel being selected for use, except that different combinations of barrel volume and needle gauge can be provided for use by the appropriate health care worker.  
         [0006]     In the manufacture of safety syringes, a number of different needle gauges must be provided. Conventional manufacturing techniques provide a different barrel size in each available needle gauge. For a safety syringe of the type shown and described in the aforementioned U.S. Pat. No. 6,626,863, each gauge of needle requires a different housing bore and a suitably sized diaphragm through which the needle passes to be in flow communication with the medicine being dispensed from the barrel of the syringe. Such multiple needle sizes for each barrel size requires many different parts and greatly increases the manufacturing complexity in providing safety needles for use by the health care industry.  
         [0007]     Syringes and disposable needles are manufactured in many different sizes, i.e. diameters and/or capacity of the syringe barrel, and in several different needle gauges for each different barrel diameter. To provide a standardized diameter for an attachable needle assembly to be mounted on the distal end of the syringe barrel, the syringe barrel would have to be configured to accept the standardized housing diameter for mounting thereon. In association with the configuration of the syringe barrel, the plunger must be operable to expel all of the fluid material from within the syringe barrel when the plunger is completely depressed. Lastly, in the instances where a safety needle assembly having a locking mechanism is utilized, the plunger must be operable to activate the locking mechanism when the plunger is completely depressed.  
         [0008]     The needle locking mechanism depicted in the aforementioned U.S. Pat. No. 6,626,863, is somewhat complex and difficult to manufacture and assemble. An improvement in the apparatus that affects a locking of the sheath in the extended position to cover the sharp tip of the needle is preferred. A reduction in the complexity of the safety needle assembly would result in lower manufacturing costs, and a resultant lower retail cost to the health care industry. By simplifying the needle locking mechanism, the complexity of the safety needle assembly would be significantly reduced.  
         [0009]     Since health care practitioners often fill the syringe barrel with the desired medication with a large bore needle to decrease the length of time to fill the syringe barrel, and then substitute a smaller gauge needle for inserting the needle into the patient&#39;s body to reduce the pain associated with the stick of the needle, the health care practitioner may mount one needle on the syringe barrel, then remove the first needle by untwisting the mounting from the receptor on the end of the syringe barrel and add a second needle to the barrel receptor. Each manipulation of the needle presents an independent risk for an accidental stick into the health care practitioner. Thus, any improvement in the handling of the needle and/or syringe would be advantageous.  
         [0010]     Accordingly, it would be desirable to provide the housing of the safety needle assembly with a convoluted outer surface to improve the ability to grip the housing for either mounting or removing the safety needle assembly on the syringe barrel receptor.  
         [0011]     It would also be desirable to provide a common needle assembly that could be utilized with a plurality of syringe barrels that would enable the same needle assembly to be used with any size syringe barrel.  
         [0012]     It would also be desirable to provide additional improvements to the safety needle assembly that would reduce the number of individual components needed for the manufacture of a safety needle assembly that could be selectively mounted on a separate syringe barrel.  
         [0013]     Accordingly, it would be desirable to provide a needle locking assembly that would be effective in the locking of the sheath in the extended position while reducing the number of parts and the complexity of manufacture of the safety needle assembly.  
       SUMMARY OF THE INVENTION  
       [0014]     It is an object of this invention to form the safety needle assembly with an outer housing that is detachably connectable to a syringe barrel.  
         [0015]     It is another feature of this invention that the outer housing of the safety needle assembly is formed with threads to facilitate the connection of the assembly to a correspondingly formed syringe barrel.  
         [0016]     It is another advantage of this invention that the Sharps disposal of the needle assembly can be reduced in volume by disconnecting the used needle assembly from the syringe barrel.  
         [0017]     It is still another feature of this invention that the needle is associated with a slidable sheath that becomes positioned over the point of the needle when the syringe plunger reaches the bottom of the barrel.  
         [0018]     It is still another advantage of this invention that the sheath-covered needle no longer presents a hazard to the health care worker as the point of the needle is covered and occluded by the sheath.  
         [0019]     It is yet another feature of this invention that the safety needle assembly includes a movable locking mechanism that is engaged by the syringe plunger to activate the sliding movement of the sheath over the needle.  
         [0020]     It is yet another advantage of this invention that the number of individual components for the construction of safety needles is reduced to greatly reduce the complexity in the manufacturing of the safety needle assemblies.  
         [0021]     It is still another object of this invention to provide a safety needle assembly that can be mounted on different sized syringe barrels.  
         [0022]     It is a further advantage of this invention that the safety needle assembly can be a common apparatus that is applicable to different sized syringe barrels to enhance the flexibility of the use of the safety needle assemblies.  
         [0023]     It is a further feature of this invention that the syringe barrels are formed with an attachment port for connection to the safety needle assembly.  
         [0024]     It is still a further feature of this invention that the attachment port has the same size irrespective of the size of the syringe barrel.  
         [0025]     It is still another object of this invention to provide an adapter that permits the connection of a standard hypodermic needle to a syringe barrel having a connection port for mounting a safety needle assembly.  
         [0026]     It is yet a further feature of this invention that a standard needle can be mounted on a syringe barrel to load medicine into the syringe barrel before being replaced with a safety needle assembly to inject the medicine into a patient.  
         [0027]     It is yet a further advantage of this invention that a large gauge standard needle can be used to draw medicine into the syringe barrel while a smaller gauge safety needle assembly can be used to inject the medicine into the patient.  
         [0028]     It is still another advantage of this invention that the standard needle can be capped before disposal thereof.  
         [0029]     It is yet another feature of this invention that the provision of an adapter on which a standard needle can be mounted provides a greater range of flexibility in the use of a safety needle assembly.  
         [0030]     It is still another feature of this invention that health care professionals can adapt their preferred manner of operation and still be able to utilize a safety needle assembly to protect against accidental sticks.  
         [0031]     It is yet another object of this invention to provide a safety needle system for selective use on differently sized syringe barrels, which safety needle system is durable in construction, inexpensive of manufacture, facile in assemblage, and simple and effective in use.  
         [0032]     These and other objects, features and advantages are accomplished according to the instant invention by providing a safety needle assembly having a rigid housing that encloses a locking mechanism, an actuator that is operable to slide a sheath over the tip of the needle to prevent accidental sticks after the needle has been used, and an actuator that is operable in response to the final end movement of the syringe plunger to effect movement of the actuator over the needle tip. The housing is made in a standard size that is mountable on a connection port formed on a syringe barrel that can have a much greater diameter than the connection port. An adapter is provided for mounting a standard needle having a Luer lock to enable a health care professional the flexibility to use conventional needles to load medicine into the syringe barrel then replacing with a safety needle assembly for injection of the medicine.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0033]     The foregoing and other objects, features, and advantages of the invention will appear more fully hereinafter from a consideration of the detailed description that follows, in conjunction with the accompanying sheets of drawings. It is to be expressly understood, however, that the drawings are for illustrative purposes and are not to be construed as defining the limits of the invention.  
         [0034]      FIG. 1  is an elevational view of the safety needle assembly incorporating the principles of the instant invention, the outer housing being broken away to show the actuator and lock mechanism within the safety needle assembly;  
         [0035]      FIG. 2  is a cross-sectional view of the safety needle assembly taken along the longitudinal centerline to reveal the internal configuration of the actuator and lock mechanism depicted in  FIG. 1 ;  
         [0036]      FIG. 3  is a cross-sectional view of an assembled syringe having a safety needle assembly mounted thereto according to the principles of the instant invention, the plunger being depicted near the end of the stroke to the bottom of the syringe barrel;  
         [0037]      FIG. 4  is a cross-sectional view of an assembled syringe having a safety needle assembly mounted thereto, similar to that shown in  FIG. 3 , but with the actuator engaged to move the sheath over the tip of the needle to prevent accidental sticks;  
         [0038]      FIG. 5  is an elevational view of the sheath head mounted within the outer housing member of the safety needle assembly;  
         [0039]      FIG. 6  is an elevational view of the sheath head oriented orthogonally to the elevational view of  FIG. 5 ;  
         [0040]      FIG. 7  is a cross-sectional view of the sheath head taken along the longitudinal centerline of the sheath head looking in the same orientation as  FIG. 6 ;  
         [0041]      FIG. 8  is an end view of the sheath head corresponding to a projection of  FIG. 7 ;  
         [0042]      FIG. 9  is an elevational detail view of the outer housing of the safety needle assembly;  
         [0043]      FIG. 10  is a cross-sectional view of the housing shown in  FIG. 9 ;  
         [0044]      FIG. 11  is a cross-sectional view of the housing looking orthogonally to the view of  FIG. 10 ;  
         [0045]      FIG. 12  is an end view of the outer housing oriented as a projection of the outer casing as oriented in  FIG. 11 ;  
         [0046]      FIG. 13  is an elevational view of the diaphragm mounted on the end of the sheath head within the safety needle housing;  
         [0047]      FIG. 14  is a elevational schematic view of the assembled components of the safety needle assembly looking orthogonally to the views of  FIGS. 1 and 2 , the needle being removed for purpose of clarity, the actuator being shown in phantom lines, the central needle support being depicted in dashed lines and the diaphragm being shown in broken lines within the outer housing;  
         [0048]      FIG. 15  is an elevational view of a 3 ml syringe barrel adapted for mounting the safety needle assembly as depicted in  FIGS. 1 and 2 , a plunger incorporating the principles of the instant invention being shown disposed within the syringe barrel;  
         [0049]      FIG. 16  is an elevational view of a 5 ml syringe barrel having a connection port at the end of the barrel for mounting the safety needle assembly;  
         [0050]      FIG. 17  is an elevational view of a 10 ml syringe barrel having a connection port for the mounting of the safety needle assembly;  
         [0051]      FIG. 18  is an elevational view of a 30 ml syringe barrel having a connection port for the mounting of the safety needle assembly, a plunger incorporating the principles of the instant invention being shown disposed within the syringe barrel;  
         [0052]      FIG. 19  is an enlarged side elevational view of an adapter for mounting a standard needle formed with a conventional Luer lock mounting apparatus;  
         [0053]      FIG. 20  is a side elevational view of an adapter mounted on the 3 cc syringe barrel depicted in  FIG. 15 ;  
         [0054]      FIG. 21  is a side elevational view of the adapter depicted in  FIG. 19  with a standard needle provided with a Luer lock mounting apparatus, the standard needle being aligned for connection to the adapter; and  
         [0055]      FIG. 22  is an elevational view of an assembled syringe needle having a standardized 3 cc syringe barrel, as depicted in  FIG. 15 , on which is mounted an adapter and a standard needle, as are depicted in  FIG. 21 .  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0056]     Referring to the drawings, the components of a safety needle assembly incorporating the principles of the instant invention can best be seen. The safety needle assembly  10  includes an outer housing  12  including a collar  13  threaded for quick connection to the receptor on a suitably configured syringe barrel. The diaphragm  15  is mounted within the housing  12  to provide a fluid-tight seal against the housing  12  and has an actuator side  16 , facing the syringe barrel  50 , and a needle side  17  from which the needle  11  projects. The needle  11  is received through the diaphragm  15 , passing through a bore  44  in a central needle support  40  and projecting outwardly therefrom in an axial manner with respect to the housing  12 .  
         [0057]     The safety needle assembly  10  further includes an actuator  20  which includes a sheath head  21  through which the needle  11  passes and is extendible therefrom. The sheath head  21  includes a body portion  22  and a pair of axially extending legs  24  that project toward the syringe barrel  50  from the body portion  22  and engage with the diaphragm  15 , as will be described in greater detail below. The sheath  25  through which the needle  11  passes is attached to the body portion  22  to form an integrally movable assembly  20  that allows the sheath  25  to extend over the needle  11  to cover the tip  11   a  of the needle  11  to prevent exposure thereof after the plunger  55  in the syringe barrel  50  has completely expelled the medicine therein through the needle  11  into the patient.  
         [0058]     The actuator  20  is movable between an exposed position, as seen in  FIG. 3 , in which the needle tip  11   a  projects outwardly from the sheath member  25  and is in an operable position for being inserted into an object, such as an IV line or a human patient. Once actuated, the sheath member  25  is movable into a covered position, best seen in  FIG. 4 , in which the needle  11  is completely covered by the sheath member  25  such that the tip  11   a  of the needle  11  is prevented from accidentally injuring someone.  
         [0059]     The collar  13  is formed with threads  14 , which are preferably located on the interior side of the collar  13  to be engagable with corresponding threads on a syringe barrel  50  located on the exterior side thereof to permit the safety needle assembly  20  to be quickly coupled to the syringe barrel  50  to form an operable safety syringe. The collar  13  is sized to mate directly on a 3 ml syringe barrel, as is depicted in  FIG. 15 . Syringe barrels  50  having a larger diameter than the standard 3 ml syringe barrel  50  are formed with a connection port  52  having the same external diameter as the end of the 3 ml syringe barrel  50 . A sloped transition portion  54  reduces the diameter of the end of the syringe barrel  50  to the 3 ml size of the connection port  52 . The connection between the collar  13  and the connector port  52  on the syringe barrel  50  can be in the form of a Luer Lock or any other appropriate quick connect apparatus that is known in the art.  
         [0060]     The safety needle assembly  20  incorporates a locking mechanism  30  that fixes the actuator  20  in the covered position. Preferably, the locking mechanism  30  is formed from a cam member  31  formed on the interior side of each of the actuator legs  24 . The cam member  31  includes a ramp portion  32  angled inwardly toward the syringe barrel  50 , as can be seen best in  FIGS. 1, 2 ,  7  and  8 , that terminates in a lock surface  33  oriented generally perpendicularly to the longitudinal centerline  19  of the safety needle assembly  10 . The cam members  31  are engagable with the central needle support  40 , as will be described in greater detail below, such that the ramp portions  32  deflect the cam member  31  outwardly until the lock surface  32  passes by the central needle support  40 , whereupon the cam members  31  retract inwardly positioning the lock surfaces  33  under the central needle support  40 . This positioning of the lock surfaces  33  under the central needle support  40  occurs as the plunger  55  forces the diaphragm  15  into the housing  12 , as will be described in greater detail below.  
         [0061]     As is best seen in  FIG. 5 , the collar  13  is preferably formed with longitudinally extending ribs  39  to facilitate the gripping of the housing  12  of the safety needle assembly  10 . Since the housing  12  must be rotated to thread the safety needle assembly  10  onto the barrel connector  52 , the ribs  39  provide a positive gripping surface for engagement by the health care practitioner&#39;s fingers. The ribs  39  are particularly advantageous when trying to remove the safety needle assembly from the syringe barrel as the housing may be tightened to the point of being difficult to grasp. Furthermore, if the health care practitioner&#39;s fingers are wet, the gripping of a smooth housing surface is unlikely to provide sufficient torque on the housing  12  to affect whether tightening or loosening.  
         [0062]     Referring to the housing  12  shown in  FIGS. 9-12 , the housing  12  is formed with a central needle support  40  along the longitudinal centerline  29  of the housing  12 . The central needle support  40  receives the needle through a bore  44  passing along the longitudinal centerline  29  through the central needle support  40  for passage into the diaphragm  15 . The central needle support  40  comprises a lower portion  42  supported on a bridge  43  extending across the diameter of the housing  12  and an upper portion  45 . The upper portion  45  projects above the bridge  43  as an extension of the lower portion  42 . The bore  44  extends continuously through the upper and lower portions  42 ,  45  of the central needle support  40 .  
         [0063]     The upper portion  45  of the central needle support  40  defines a tubular mount at the center of an upper chamber  46  of the housing  12 . The diaphragm  15  is mounted for axial movement along the housing on the upper portion  45  which forms a central mount for the diaphragm  15 . As noted above, the needle  11  passes through the bore  44  into the diaphragm  15  to be in flow communication with the syringe barrel  50 . By standardizing the size of the housing  12 , and by standardizing the outer diameter of the upper portion  45  forming the central mount in the upper chamber  46 , the size and shape of the diaphragm  15  can also be standardized to reduce substantially the number of different parts required to make safety needle assemblies  10  with different needle gauges.  
         [0064]     The bore  44  will be sized to match the gauge of the needle being utilized in the safety needle assembly, but the magnitude of the diameter of the bore  44  has no bearing on the outer diameter of the upper portion  45  and, thus, the size and shape of the diaphragm  15  can be standardized to fit within the upper chamber  46 . While the outer dimensions of the housing  12  will not vary, the diameter of the bore  44  will vary according to the gauge of the needle  11  being utilized in the safety needle assembly  10 . Nevertheless, the formation of the housing  12  can be common with all needle gauges until the bore  44  is drilled into the central needle support  40 . Furthermore, the utilization of the upper portion  45  of the central needle support  40  provides additional stability for the needle  11 , as the longer support member  40  through which the bore  44  extends reduces the ability of the needle  11  to move laterally within the safety needle assembly  10 .  
         [0065]     Further commonizing the syringe barrel  50  is necessary for the utilization of a common diameter safety needle assembly. As noted above, the outer housing  12  is sized to fit on the smallest commonly used syringe in medical practice, the 3 ml syringe. Accordingly, as can be seen in  FIG. 15 , the 3 ml syringe barrel  50  is formed simply with a grip portion  58  at the upper end thereof and a threaded outer surface  59  at the lower end of the syringe barrel  50 . Otherwise, the barrel  50  is open at the lower end. Typically, the syringe barrel  50  will be shipped in a sterilized package with a suitable sized plunger  55  inserted into the barrel  50 . The syringe barrel  50  could be formed with a barrel lock device (not shown) that fixes the plunger  55  in the barrel  50  when the plunger  55  reaches the end of the stroke at the bottom of the barrel  50 . One skilled in the art will recognize that the use of a barrel lock (not shown) is not needed for proper operation of the safety needle assembly  10  as will be described in greater detail below.  
         [0066]     As reflected in  FIGS. 16-18 , syringe barrels  50  that have a larger capacity than 3 ml can also be manufactured to accept the mounting of a safety needle assembly  10 . More particularly, the open lower end of the syringe barrel  50  can be formed with a connection port  52  that has the same diameter as the 3 ml barrel  50 . To carry a greater supply of medicine, the general diameter of the barrel  50  is larger than the 3 ml barrel. However, the lower end of the barrel  50  can be formed with a connection port  52 , as is depicted in  FIGS. 16-18 , that will accept the standardized size of the housing  12 . A sloped transition portion  54  reduces the diameter of the barrel  50  from the sized necessary to define the appropriate capacity of the barrel to the common 3 ml size of the connection port  52 . The transition portion  54  is sloped, instead of perpendicular to the centerline  29  of the barrel  50 , so that the medicine within the barrel  50  can be completely dispensed to the patient when the plunger  55  is completely depressed into the syringe barrel  50 .  
         [0067]     Each plunger  55  can be formed to tailor-fit each syringe barrel  50  in terms of diameter of the barrel  50  and in terms of mating with the transition portion  54  so that all of the medicine in the syringe barrel  12  will be dispensed when the plunger  55  is completely depressed. As can be seen in  FIGS. 15 and 18 , the plunger  55  is shaped to mate with the transition portion  54  of the barrel  50 , and includes an actuation tip  57  that extends into the housing  12  of the safety needle assembly  10  to move the diaphragm  15  as will be described in greater detail below.  
         [0068]     Assembly of the safety needle assembly requires the formation of a standard housing  12 , a standard diaphragm  15 , a needle  11  having a selected gauge, and an actuator  20 , including the body portion  22  with the legs  24  extending axially therefrom and a sheath member  25  affixed to the body portion  22  and extending in the opposite direction from the legs  24 . The actuator  20  is mounted into the housing  12  with the legs  24  extending on opposing sides of the bridge  43 . The tips of the legs  43  are formed in a shape, as is best seen in  FIGS. 5-7 , having a protruding lip  36  that is sized to mate with a matched cavity  19  formed in the diaphragm  15 . Thus, the legs  24  are engaged into the cavities  19  in the diaphragm  15  so that the diaphragm  15  is mounted on the actuator  20 . The diaphragm  15  is located in the upper chamber  46  of the housing  12  and mounted on the central mount  45  to be movable axially along the central mount  45 . The needle  11  is passed through the sheath member  25  and the body portion  22  of the sheath head  21 , passing through the appropriately sized bore  44  and through the diaphragm  15  to be in flow communication with the barrel  50  when mounted the safety needle assembly  10  is mounted thereon.  
         [0069]     In operation, the health care worker would select the barrel  50  having a plunger  55  with a rubber seal  56  positioned within the barrel  50 , with the barrel  50  being open at the distal end where the connector  52  is located with threads  53  thereon being located preferably on the exterior surface thereof. The safety needle assembly  10  is then selected with the needle  11  protected by a safety cap (not shown). The collar  13  having the threads  14  (or outwardly projecting ribs as in a Luer Lock) positioned preferably on the interior surface thereof is then engaged with the connector  52  on the barrel  50  and twisted into a locking engagement therebetween. Once the safety cap is removed, the assembly safety syringe with detachable safety needle assembly  10  is ready for utilization.  
         [0070]     As with conventional syringes, the assembled two-piece safety syringe is operated by withdrawing the plunger  55  to affect the intake of liquid medicine into the barrel  50 . Once air has been ejected from the barrel  50 , the needle  11  and tubular sheath member  25  are inserted into the selected target. Depressing the plunger  55  expels the liquid medicine through the needle  11  and into the selected target until the plunger  55  bottoms out against the diaphragm  15 . At this point, the plunger  55  is not completely inserted into the barrel  50 , as some additional linear movement of the plunger  55  remains available to actuate the locking mechanism  30 .  
         [0071]     This last movement of the plunger  55  drives the diaphragm  15  axially along the central mount  45  deeper into the upper chamber  46  of the housing  12 . The axial movement of the diaphragm  15 , due to the engagement of the legs  24  in the cavities  19  of the diaphragm  15 , pushes the actuator  20  along the longitudinal center axis  29  of the assembly  10  outwardly to move the tubular sheath member  25  into the covered position over the needle tip  11   a . The locking mechanism  30  engages when the actuator  20  has moved into the covered position, which preferably corresponds to the plunger  55  bottoming out into the barrel  50 .  
         [0072]     The locking mechanism  30  is engaged due to the axial movement of the actuator  20  in response to the plunger  55  driving the diaphragm  15  deeper into the upper chamber  46  of the housing  12 . The cam members  31  formed on the interior side of the legs  24  move axially with the rest of the actuator  20 , with the sloped ramp portions  32  springing the legs  24  slightly outwardly as the cam members  31  pass the bridge  43  supporting the central needle support  40  within the housing  12 . Once the lock surfaces  33  pass below the bridge  43 , the legs  24  spring back into position driving the lock surfaces  33  under the bridge  43 , which will restrict the return of the cam members  31 , and then the actuator  20  back past the bridge  43 .  
         [0073]     With the needle  11  covered, the needle  11  and tubular sheath member  25  are withdrawn from the selected target. Since the locking mechanism  30  prevents the actuator  20  from moving out of the covered position, the point  11   a  of the needle  11  will not be exposed to present an opportunity for an accidental stick into the health care practitioner, or to present an opportunity for the safety needle assembly  10  to be re-used, whether remaining engaged with the barrel  50 , or removed from the barrel  50 .  
         [0074]     The safety needle assembly  10  is intended for use on a syringe barrel  50  configured as shown in  FIGS. 15-18  with a connector port  52  having threads  53  preferably formed on the exterior surface thereof to mate with the threads  14  on the interior surface of the collar  13  of the safety needle assembly  10 . The size or gauge of the safety needle assembly  10  is preferably maintained at a given configuration, such as is conventional for a 3 cc syringe, so that production of the safety needle assembly  10  can be economical. Rather than form the safety needle assembly  10  with different sized housings  12  and collars  13  for connection to the correspondingly different sized syringe barrels  50 , having conventional capacities of between 3 cc and 60 cc, the housing  12  and collar  13  are formed at a standard size and the barrels  40  of the syringes are formed to mate with the standardized safety needle assembly  10 .  
         [0075]     As can be seen in  FIGS. 16-18 , the barrels  40  having a capacity greater than the conventional 3 cc syringe size are formed with a transition portion  54  that reduces the diameter of the barrel  50  from the conventional diameter corresponding to the particular sized syringe being utilized to the connector port  52  diameter corresponding to the standardized safety needle assembly  10 . This transition portion  48  is formed with angularly sloped walls that span between the larger diameter of the large syringe barrel  50  to the standardized connector  52  diameter.  
         [0076]     The plunger  55  must then be formed with a mating configuration that closes against the sloped sides of the transition portion  54  when the plunger  55  is completely depressed into the barrel  40  so that all of the fluid material within the barrel  40  is expelled from the barrel  50  through the needle  11 . The seal  56  at the end of the plunger  55  will be formed with a tapered tip  57  that will extend into the housing  12  of the attached safety needle assembly  10  to actuate the locking mechanism  30  therein by engaging the diaphragm  15  when the plunger  55  has been fully depressed into the barrel  50 . The tapered shape of the tip  57  allows the last droplets of the fluid material within the barrel  50  to pass out of the barrel  50  and around the tip  57  to reach the diaphragm  15  and be expelled through the needle  11 . Alternatively, the tip  57  could be have a constant diameter that is formed with one or more grooves extending axially along the tip  57  to permit the passage of liquid medicine from the barrel  50  as the plunger seal  56  bottoms out at the tapered transition portion  54 .  
         [0077]     Some health care practitioners prefer to draw medicine into the syringe barrel  50  with a large gauge needle so that the barrel  50  fills more rapidly. Such large gauge needles are then replaced with a smaller gauge needle that is inserted into the patient to inject the medicine from the syringe barrel  50 . Furthermore, some health care practitioners prefer to inject medicines into their patient with a “fresh” needle having a point that hasn&#39;t been dulled through previous usage. While this practice is possible with the safety needle assembly  10  described above, utilizing a large gauge safety needle assembly  10  just to draw medicine into the syringe barrel  50  would be cost prohibitive. Accordingly, an alternative configuration that would enable the syringe barrels  50 , as described above, to be utilized with a common standard needle  65  having a Luer lock  66  mounting apparatus.  
         [0078]     Referring now to  FIGS. 19-22 , an adapter  60  is provided with a mounting collar  61  that is sized and threaded to mount on the connection port  52  of the syringe barrel  50  and an integral connection bell  62  that incorporates Luer lock threading  64  on the inside thereof. The connection bell  62  includes a tip  63  that engages into the needle hub  67  to direct the medicine from the barrel  50  into the attached standard needle  65  that is mounted thereon as described below. Instead of mounting a safety needle assembly  10  on the connection port  52  of the syringe barrel  50 , the adapter  60  can be mounted, as is depicted in  FIG. 21 , so that a common standard needle  65  can be mounted on the adapter  60 , as is reflected in  FIGS. 22 and 23 .  
         [0079]     In operation, the health care practitioner can start by selecting a syringe barrel  50  of the size needed to dispense the quantity of medicine needed. An adapter  60 , which could come packages with the standard needle  65  already mounted thereon or as a separate component so that any desired size of common standard needle  65  can be mounted thereon, is mounted on the connection port  52  by screwing the mounting collar  61  thereon. The desired common needle  65  can then be selected, which typically comes packaged with a safety cover (not shown) mounted thereon, and mounted into the connection bell  62  by threading the Luer Lock ribs  66  into the threaded connection bell  62 . Typically, this will be a large gauge needle  65  that will rapidly draw the medicine into the syringe barrel  50 .  
         [0080]     After the medicine is drawn into the syringe barrel  50 , the uninfected needle  65  can be recovered with the safety cover (not shown), then the adapter  60  removed from the connection port  52  and properly disposed in a Sharps container. The safety needle assembly  10  can then be mounted on the connection port, as described above, air ejected out of the barrel  50  and then inserted hypodermically into the patient to inject the medicine. The safety needle assembly  10 , locked into a covered position by the lock mechanism actuated by the plunger reaching its end movement, can then be safely removed from the syringe barrel  50  and properly disposed in the Sharps container. The syringe barrel  50  can be disposed in either the Sharps container or in another appropriate manner to make use of recycling and reduce the hazardous waste disposal.  
         [0081]     The standardized safety needle assembly  10  can be produced in mass production and packaged in a sterile container in a conventional manner. Since the only variation in the safety needle assembly  10  will be the gauge of the needle  11  being selected, the number of needle varieties that must be available is significantly reduced, as each available gauge of needle does not have to be manufactured in each barrel diameter. The application of the safety needle assembly  10  to a particular syringe barrel  50  requires the manual grasping of the housing  12  of the safety needle assembly  10  in one hand and a grasping of the syringe barrel  50  in the other hand, following by a turning motion to engage the housing collar  13  with the connection port  52  to attach the housing  12  of the safety needle assembly  10  on the syringe barrel  50 . This connection of the safety needle assembly  10  requires only that the collar  13  on the housing  12  be threaded onto the connector port  52  of the barrel  50  by engaging the respective threads and turning.  
         [0082]     While the concept of a standardized needle assembly diameter that would fit on a connector port having a diameter corresponding to the attachable needle housing would apply to any form of needle assembly, the concept is particularly advantageous with respect to the utilization of safety needle assemblies  10  because of the manufacturing requirements of providing many different diameters of housings that would otherwise be needed to mate with the differently sized syringe barrels  50 . Thus the use of safety needle assemblies is further facilitated while minimizing accidental sticks after prior utilization and discouraging and preventing re-use of the needle. In addition, as is disclosed in aforementioned U.S. Pat. No. 6,626,863, the plunger  55  can also be provided with an internal locking mechanism between the plunger  55  and the walls of the barrel  50  to prevent the withdrawal of the plunger  55  from the barrel  50  once completely depressed into the barrel  50 .  
         [0083]     The invention of this application has been described above both generically and with regard to specific embodiments. Although the invention has been set forth in what is believed to be the preferred embodiments, a wide variety of alternatives known to those of skill in the art can be selected within the generic disclosure.  
         [0084]     It will be understood that changes in the details, materials, steps and arrangements of parts which have been described and illustrated to explain the nature of the invention will occur to and may be made by those skilled in the art upon a reading of this disclosure within the principles and scope of the invention. The foregoing description illustrates the preferred embodiment of the invention; however, concepts, as based upon the description, may be employed in other embodiments without departing from the scope of the invention.