Abstract:
A spring loaded retractable needle syringe comprising a body, a central tube coaxially mounted within said body, a needle carrier and needle slidably mounted within said central tube, a spring mounted within said central tube to bias said needle carrier and needle into said central tube, means for sliding said needle carrier and needle within said central tube to compress said spring and expose said needle, means for retaining said needle carrier and needle in the exposed position against the biasing force of said spring, and means for releasing the needle carrier and needle such that said needle carrier and needle are retracted into said central tube.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a retractable needle safety syringe in which the needle may be withdrawn into the barrel of the syringe after use. More particularly the invention relates to a retractable needle syringe wherein the plunger need not be connected to the needle or its carrier for the retraction. Most particularly the invention relates to a retractable needle syringe wherein the needle carrier is spring loaded so that it may be automatically retracted into the syringe barrel after use.  
         [0003]     2. Related Art  
         [0004]     Due to the recent advent of the AIDS virus, which may be contracted by contaminated hypodermic syringes, there have been several retractable needle hypodermic syringes invented and patented. The retraction of the needle into the barrel of the syringe after use reduces the risk of “needle prick”, or the accidental pricking of the person giving the injection after the syringe has been used.  
         [0005]     Some of the recently patented retractable needle syringes include U.S. Pat. No. 4,692,156 (Haller); U.S. Pat. No. 4,675,005 (DeLuccia); U.S. Pat. No. 4,747,830 (Gloyer, et al); U.S. Pat. No. 4,790,822 and U.S. Pat. No. 4,950,251. All of the syringes disclosed include a hypodermic needle mounted on a carrier which is slidable in the barrel. The plunger is locked to this carrier after the injection has been given and is withdrawn up into the barrel by withdrawal of the plunger. The simplest mechanism for locking the plunger to the carrier is disclosed as a projection on the lower end of the plunger which engages through an opening in the upper end of the carrier.  
         [0006]     One disadvantage of the above syringes is that the locking mechanism takes up some space in the barrel of the syringe and may prevent all of the measured liquid from being ejected by the plunger. This problem is exacerbated in the very small syringes such as the 1 cc tuberculin type. The liquid left in the barrel may be a substantial portion of the measured dose. In addition the narrowness of the barrel of the 1 cc syringe makes it difficult to design a needle carrier and locking mechanism that will fit in the barrel without enlarging the diameter so much as to make the calibration useless.  
         [0007]     Venturini in U.S. Pat. No. 5,112,316 discloses a syringe similar to the retractable needle syringes described above except Venturini adds a spring outside the upper end of the syringe between the finger flange on the top of the barrel and the bottom surface of a projection at the top of the plunger to retract the plunger into the barrel after it has been locked onto the needle carrier. Venturini suffers the same draw backs because the plunger must still be locked to the needle carrier.  
       SUMMARY OF THE INVENTION  
       [0008]     The present invention provides a syringe which allows the needle to retract into a safe position inside the barrel or syringe body after use to prevent needle pricks to the user. In the initial state or unused position the needle is held fully captive by means of a spring and protected by a center tube which eliminates the need for a needle cap. A safety ring on the plunger holds the needle in the initial safe position. This ring is broken from the plunger by pressure on the plunger thus requiring only one hand to extend the needle for use. After use the needle is retracted into body by means of a spring. Again, only one hand operation is required to trigger the retraction by means of a second aggressive push on the plunger. A locking cap is provided which covers the open end of the body making a sealed assembly for disposal.  
         [0009]     Briefly, the invention is spring loaded retractable needle syringe comprising a body, a central tube coaxially mounted within said body, a needle carrier and needle slidably mounted within said central tube, a spring mounted within said central tube to bias said needle carrier and needle into said central tube, means for sliding said needle carrier and needle within said central tube to compress said spring and expose said needle, means for retaining said needle carrier and needle in the exposed position against the biasing force of said spring, and means for releasing the needle carrier and needle such that said needle carrier and needle are retracted into said central tube. 
     
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0010]      FIG. 1  is an isometric view of device of the present invention.  
         [0011]      FIG. 2  is a side plan view of the device in the initial state.  
         [0012]      FIG. 3  is a side plan view in cross section taken along line  3 - 3  of  FIG. 2 .  
         [0013]      FIG. 4  is a second isometric view of the device from an angle different than that of  FIG. 1 .  
         [0014]      FIG. 5  is a side plan view of the device with the needle in the extended position.  
         [0015]      FIG. 6  is a side plan view of in cross section taken along line  6 - 6  of  FIG. 5 .  
         [0016]      FIG. 6A  is an enlarged cross sectional view of the area circled in  FIG. 6 .  
         [0017]      FIG. 7  is a side plan view of the device in the release phase of operation.  
         [0018]      FIG. 8  is a side plan view in cross section taken along line  8 - 8  of  FIG. 7 .  
         [0019]      FIG. 8A  is an enlarged cross sectional view of the area circled in  FIG. 8 .  
         [0020]      FIG. 9  is a side plan view of the device with the needle in the safe stowed position after use.  
         [0021]      FIG. 10  is a side plan view in cross section taken along line  10 - 10  in  FIG. 9 .  
         [0022]      FIG. 11  is an exploded view of the device.  
         [0023]      FIG. 12  is a side plan view of the device with a safety cap in place.  
         [0024]      FIG. 12A  is an enlarged cross sectional view taken along line  12 A- 12 A in  FIG. 12 . 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0025]     For a detailed description of the preferred embodiment the reader is referred to the appended figures in which like components are given like numerals for ease of reference.  
         [0026]     For quick reference all of the reference numerals are listed in Table I below and their corresponding parts identified with the figures in which the parts are identified. The parts may be shown in other figures but are identified by the reference numerals in the listed figures only.  
                                 TABLE I                       Ref. No. Description   Identified in FIG. Number:                                 1   Syringe Body   1-6, 6A, 8, 8A, 10-12, 12A        2   Plunger   1-6, 8, 8A, 10, 11        3   Plunger Seal   3, 6, 8, 10, 11        4   Needle Carrier   3, 6, 6A, 8, 8A, 10, 11        5   Needle   1, 3, 5, 6, 8, 11        6   Center Tube   3, 6, 6A, 8, 8A, 10, 11, 12A        7   Plunger Retaining Ring   1-6, 8, 10        8   Ring Snap-off Tab   3, 4        9   Spring   3, 6, 8, 10, 11       10   O-ring   3, 6, 6A, 8, 10, 11       11   Center Tube Flow Aperture   3, 6, 6A, 8, 10, 11       12   Needle Carrier Flow Aperture   3, 6, 6A, 8, 10       13   Needle Carrier Flow Ring   3, 6, 6A, 8, 10, 11       14   Luer Seal   3, 6, 8, 10       15   Spring Retainer Surface   3, 6, 8, 10       16   Needle Aperture   3, 6, 8, 10, 12A       17   Center Tube Retaining Ring   3, 6, 10, 11       18   Seal Retaining Finger   3, 6, 8, 10       19   Center Tube Wiper   3, 6, 8, 10       20   Syringe Body Wiper   3, 6, 8, 10       21   Needle Retainer Notch   3, 6, 8, 8A, 10, 11       22   Needle Release Notch   3, 6, 8, 8A, 10, 11       23   Plunger Inner Cavity   3, 6, 8, 8A, 10       24   Needle Carrier Actuator   3, 6, 8, 8A, 10, 11       25   Needle Carrier Actuator   3, 6, 8, 8A, 10           Retainer Latch       26   Needle Carrier Actuator   3, 6, 8, 8A, 10, 11           Retainer Snap       27   Needle Carrier Actuator   3, 6, 8A, 10           Inner Cavity       28   Needle Carrier Actuator   3, 6, 8, 10           Push Surface       29   Plunger Push Surface   3, 6, 8, 10       30   Needle Carrier Actuator   3, 6, 8, 8A, 10           Latch Release Surface       31   Center Tube Release Cone   3, 6, 8, 8A, 10, 11       32   Needle Carrier Actuator   3, 6, 8, 8A, 10, 11           Release Slot       33   Center Tube Inner Cavity   3, 10       34   Flow Path   6A       35   Syringe Body Inner Cavity   3, 6, 6A       36   Safety Cap   12, 12A       37   Cap Snap Retainer   12A                  
 
         [0027]     Referring first to  FIGS. 2-4  the device is shown in its initial state, or as shipped with the needle  5  inside the body  1 . The needle  5  is molded within the needle carrier  4  and is captured in the center tube inner cavity  33 . The needle carrier  4  is biased by spring  9  against spring retaining surface  15  to maintain this position with the needle  5  fully retracted into the center tube  6 . The center tube  6  is held to the syringe body  1  by means of a snap-in center tube retaining ring  17  and the luer seal  14 . The needle carrier actuator  24 , inside the plunger inner cavity  23 , rests on top of the needle carrier  4  by the needle carrier actuator retainer latch  25 . The plunger  2  rests on the needle carrier actuator  24  by means of the needle carrier actuator push surface  28 . As shown in  FIG. 4  plunger  2  is held in position by the plunger retaining ring  7  and a plurality of ring snap-off tabs  8 .  
         [0028]     Referring now to  FIGS. 5 and 6  the initial exposing of the needle is disclosed. To expose the needle  5  for use, the plunger  2  is depressed into the syringe body  1  by applying pressure to the plunger push surface  29 , thereby breaking the snap-off tabs  8  on plunger retaining ring  7 . This allows the needle carrier actuator  24  to be driven toward the distal end in tandem with the needle carrier actuator  24  and the needle carrier  4  and needle  5  by means of the needle carrier actuator retainer latch  25 , until the needle carrier actuator retainer snap  26  on the needle carrier actuator  24  engages the needle retainer notch  21  on the center tube  6 . The needle carrier actuator retainer latch  25  drives the needle  5  through the needle aperture  16  and the needle carrier actuator retainer snap  26  locks the needle  5  in the extended position as required for an injection.  
         [0029]     Referring to  FIG. 6A , when the needle  5  is in the extended position the needle carrier flow aperture  12  in the needle carrier  4  aligns with the center tube aperture  11  in the center tube. This enables the flow path  34  confined by o-ring  10  located on either side of the needle carrier flow aperture  12  on needle carrier  4 . The needle carrier flow ring  13  allows radial movement of the needle carrier  4  relative to the center tube  6  to prevent compromising the flow path  34 . Referring again to  FIG. 6 , the injectable fluid resides in the syringe body inner cavity until plunger  2  is depressed, pushing the plunger seal  3  towards the distal end of the syringe body  1 . Plunger seal  3  seals against the inner wall of the syringe body  1  by means of the syringe body wiper  20 , and the against the center tube  6  by means of the center tube wiper  19 . This sealing action forms a seal to expel the fluid in the syringe body inner cavity  35  along the flow path  34  and through needle  5 . The plunger seal  3  is held to the plunger  2  by a plurality of seal retaining fingers  18  as best shown in  FIG. 11 . Note also that the spring  9  is isolated from the injection fluid by the o-rings  10  at all times. The flow path  34  enters the needle carrier aperture  12  and flows through the needle  5  without contacting the spring  9 .  
         [0030]     Referring now to  FIG. 8 , after the injection is administered, the plunger  2  is depressed further into the syringe body  1  causing the plunger seal to be compressed between the plunger  2  and the distal inside surface of the syringe body  1 . This allows for further movement of the needle carrier actuator  24  as is it contacted at the needle carrier push surface  28  by the inside surface of the plunger  2 . As shown in  FIG. 8A , this movement causes the needle carrier actuator retainer snap  26  to engage the needle release notch  22  on the center tube  2 . In this position the needle carrier actuator latch release surface  30  contacts the center tube release cone  31 . This in turn causes the needle carrier actuator retainer latch  25  to be spread apart and away from the top surface of the needle carrier  4 , relieved by the needle carrier actuator release slot  32 , allowing room for the needle carrier  4  to slide by the needle carrier actuator retainer latch  25  as it is biases upward by spring  9  against spring retaining surface  15 , and into the needle carrier actuator inner cavity  27 . As shown in  FIG. 10 , when the needle carrier  4  is fully inserted into the needle carrier actuator inner cavity  27 , the needle  5  is fully encased by the center tube  6  and the administrator is safe from needle pricks. The plunger  2  remains with the assembly and captures the needle carrier  4  and needle actuator  24 .  
         [0031]     Finally, as shown in  FIGS. 12 and 12 A a safe cap  36  is pressed on the syringe body to completely seal the needle aperture  16 . The safety cap  36  snaps into a cap snap retainer groove  37  on the syringe body and is unremovable.  
         [0032]     The foregoing description of the invention has been directed to a particular preferred embodiment of the present invention for the purposes of explanation and illustration. It will be apparent to those skilled in the art that many modifications and changes in the apparatus may be made without departing from the scope and spirit of the invention. It is therefore intended that the following claims cover all equivalent modifications and variations as fall within the scope of the invention as defined by the claims.