Abstract:
A syringe for use with a carpule and needle is provided. The syringe comprises: (i) a holder for accepting the carpule, the holder comprising at least two linearly disposed first mating members; (ii) a plunger for engagement with the holder; and (iii) a shell for slidably housing the holder, the shell having a distal aperture and a proximal aperture, with a bore therebetween, the shell comprising at least one integral biased member proximate to the proximal aperture, the biased member having a second mating member proximate to a distal end, for mating with the first mating member, such that in a first position, the needle is housed within the shell and in a second position, the needle extends at least partially from the shell.

Description:
[0001]    This application is a Continuation-in-Part of co-pending U.S. application Ser. No. 12/002,117, filed Dec. 13, 2007, herein incorporated by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates to a syringe for use with a carpule and needle, more specifically, to a retractable syringe that permits the needle to be obscured from view as desired. 
       BACKGROUND ART 
       [0003]    In recent years there has been growing concern related to the safety of syringes. Conventional needles are provided with a cap or cover which is removed once the needle is affixed to the syringe. At this time, there is a potential for the practitioner or the patient to be inadvertently stuck with the needle or for contamination of the needle. Syringes with retractable needles have been developed to overcome these issues and enable the practitioner to expose the needle only when necessary. 
         [0004]    Typically, a retractable needle has two positions, retracted and extended. The needle must be placed in the fully extended position in order to prepare the needle for administration of the injection by depression of a plunger and dispensing of the carpule contents. In addition, many retractable needles such as the SMART SYRINGE® (SMART SYRINGE is a registered trademark of Sakharam Mahurker, Chicago, Ill., USA) provide only a single use and are not environmentally friendly. 
         [0005]    In the field of dentistry, injections are a common fear identified in dental patients. Recent studies have shown that both the patient and the dentists may be traumatized on viewing the needle portion of a syringe when receiving dental syringe injections. There have many dental syringes developed specifically to reduce or eliminate patient anxiety on receiving injections. These syringes are typically marketed as “patient friendly” syringes, however “patient friendly” has often referred to a reduced time period associated with receiving an injection not needle related anxiety. 
         [0006]    The Wand® (The Wand is a registered trademark of Milestone Scientific Inc., Livingston, N.J., USA) is a computer controlled dental injection system that is intended to alleviate or reduce patient pain and anxiety associated with receiving injections by controlling the speed at which the injection is administered by a computer. The Wand® resembles a ballpoint pen and is easier for dentists to handle because its light weight. However, this device is both costly to purchase and operate, and time consuming to prepare and perform the injection. 
         [0007]    The Comfort Control® Syringe (Comfort Control is a registered trademark of Midwest Dental Products Corp., Des Plaines Ill., USA) was developed to deliver a more predictable and comfortable injection in sensitive areas such as the palate or front of the mouth. The syringe is wired to a microprocessor which directs a steady, slow injection regardless of tissue density. 
         [0008]    Another device, the Vibraject provides a motor attached to a conventional syringe that causes the needle portion of the syringe to vibrate. The high vibration of the needle stimulates the nerve endings and blocks the transmission of pain to the brain. 
       SUMMARY 
       [0009]    Exemplary embodiments of the present invention relate to a syringe assembly having an extendable and retractable outer shell for exposing a needle. 
         [0010]    An exemplary embodiment relates to a syringe assembly comprising a holder for receiving a container having a medicament, a plunger slidably received in the holder and an outer shell having an inner surface where a portion of the inner surface slidably engages an outer surface of the holder. A forward end of the plunger selectively engages the container to dispense the medicament through a needle. The outer shell is movable between an extended position and a retracted position for exposing the needle. The plunger and the holder are movable as a unit relative the outer shell when the outer shell moves between the extended position and the retracted position. When the outer shell is in the retracted position, the plunger is movable to a dispensing position. 
         [0011]    In one embodiment, a proximal end of the outer shell is biased toward the holder. The proximal end may include a protrusion for selectively engaging a depression in the outer surface of the holder, and the outer shell is then biased toward the depression. 
         [0012]    An alternative exemplary embodiment relates to an outer shell for a syringe comprising an inner surface, a portion of said inner surface slidably engaging an outer surface of a holder and a proximal end biased toward the holder for selectively engaging the outer surface of the holder. The holder is configured for receiving a container having a medicament. The outer shell is movable between an extended position and a retracted position for exposing a needle. When the outer shell moves between the extended position and the retracted position, a plunger slidably received in the holder, and the holder are movable as a unit relative to the outer shell. When the outer shell is in the retracted position, a forward end of the plunger is movable relative to the holder in a dispensing direction to dispense the medicament through the needle. 
         [0013]    In one embodiment, the proximal end further includes a protrusion for selectively engaging a depression in the outer surface of the holder. The protrusion of the outer shell is biased toward the depression. 
         [0014]    In another embodiment, the outer surface of the holder has a first depression and a second depression. When the protrusion engages the first depression, the position of the outer shell corresponds to the extended position. When the protrusion engages the second depression, the position of the outer shell corresponds to the retracted position. In a further embodiment, the protrusion is formed on an inner wall of the outer shell. 
         [0015]    In another embodiment, the holder further includes a channel formed in the outer surface. The channel continuously engages the protrusion of the outer shell. In yet another embodiment, the depression is formed in the channel. 
         [0016]    In one embodiment, the outer surface of the holder further includes at least one intermediate depression. In another embodiment, the outer surface of the holder further includes two intermediate depressions. In yet another embodiment, the outer surface of the holder further includes a plurality of intermediate depressions. When the protrusion engages an intermediate depression, the position of the outer shell corresponds to a partially retracted position. 
         [0017]    In one embodiment, an outer wall of the outer shell has a window formed therein. 
         [0018]    In another embodiment, the syringe assembly further includes a spring biased toward the container for resiliently retaining the container in the holder. 
         [0019]    In one embodiment, the outer shell is transparent. In another embodiment, a portion of a distal end of the outer shell is textured to obscure the needle. 
         [0020]    In one embodiment, the syringe assembly is self-aspirating. 
         [0021]    In a further embodiment, the outer shell is constructed of a suitable flexible material that is temporarily deformable. The suitable flexible material is selected from the group consisting of plastics, metals, compliant polymeric material and combinations thereof. The compliant polymeric material may be shaped into a child-friendly shape, for example an animal head, an animal, or a tooth. A portion of the proximal end of the outer shell may further include an outer coating of a compliant polymeric material. 
         [0022]    In one embodiment, the outer shell is injection molded. Alternatively, the syringe assembly may be injection molded. 
         [0023]    The foregoing and other features and advantages of the syringe assembly will become more apparent from the following detailed description, which proceeds with reference to the accompanying figures. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]    Embodiments of the present invention will now be described, by way of example only, with reference to the attached Figures, wherein: 
           [0025]      FIG. 1  is an isometric view of an embodiment of a syringe assembly with a needle extended; 
           [0026]      FIG. 2  is an isometric view of the syringe assembly shown in  FIG. 1  with the needle retracted; 
           [0027]      FIG. 3  is an isometric view of a portion of the syringe assembly of  FIG. 1  having an outer shell removed; 
           [0028]      FIG. 4  is a portion of the syringe assembly shown in  FIG. 1  in section showing depressions in a holder of the syringe; 
           [0029]      FIG. 5  is a top view, partially in section, of an exemplary embodiment of the syringe assembly; and 
           [0030]      FIG. 6  is a top view, partially in section, of an exemplary embodiment of the syringe assembly; and 
           [0031]      FIG. 7  is an isometric view of a portion of the syringe assembly shown in  FIG. 2  showing a section of an inner wall of the outer shell. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0032]    Some exemplary embodiments of the present invention relate to a syringe having a needle that is retractable and extendable such that the needle may be advanced through a series of specific needle positions, until the needle is fully extended. 
         [0033]    A carpule syringe facilitates repeated use, specifically repeated loading of carpules and enables easy insertion of doses of a medicament and discharge of exhausted containers. A carpule is a container or cartridge having a medicament therein. A carpule syringe is characterized by the absence of a fixed barrel in which a piston reciprocates. Instead, a carpule syringe includes a shell with an opening designed to receive a medicament filled carpule, the ends of which are closed and hermetically sealed. The frame is provided with a reciprocatable shaft arranged to engage with one end of the carpule such that when the shaft is pushed forwardly in the frame, it will apply pressure to the liquid medicament within the carpule so as to dispense the same through a needle. 
         [0034]    Referring to  FIG. 1 , an isometric view of an embodiment of a syringe assembly  10  with a needle  14  extended is generally shown. The syringe  10  is used in combination with a carpule  12  and a needle  14 . The carpule  12  is typically formed from glass or other transparent material is of conventional design well known in the art. Carpule  12  is typically filled with a supply of fluid medication, such as novocaine, or the like. In one exemplary embodiment the outer shell  16  further comprises a window  20  to enable viewing of carpule  12 , and the quantity of medicament therein. 
         [0035]    Referring to  FIG. 2 , an isometric view of an embodiment of a syringe  10  with a needle  14  retracted is generally shown. The syringe assembly  10  includes a hollow outer shell  16  that slidably engages at least a portion of an outer surface  21  of holder  18  and a plunger  24  slidably received in holder  18 . The outer shell  18  is movable between an extended position shown in  FIG. 1  and a retracted position shown in  FIG. 2  for exposing the needle  14 . In a further exemplary embodiment, the plunger  24  further includes a gauge for indicating the quantity of medicament in the carpule  12 . 
         [0036]      FIG. 3  illustrates an isometric view of an exemplary embodiment of a portion of the syringe  10  having the outer shell  16  removed. The holder  18  includes an aperture  15  for receiving the carpule  12  therein. A distal end  22  of the holder  18  has an aperture configured to receive a needle  14 . A portion of plunger  24  extends outwardly from the proximal end  26  of the holder  18 . 
         [0037]    Referring to  FIG. 4 , a portion of the syringe assembly  10  is generally shown. The outer surface  21  of holder  18  includes at least one depression  31 ,  32 ,  35 ,  36  for selectively engaging a protrusion  50  located at a proximal end  48  of the outer shell  16 . In one exemplary embodiment, the protrusion  50  is formed on the inner wall  28  of the outer shell  16 . The outer surface  21  of holder  18  includes a first depression  36  that defines a first position  38 , and a second depression  32  that defines a second position  34 . The second depression  32  is proximate to the proximal end  26  of holder  18 , and the first depression  36  is distal to the second depression  32 . The distance between the first depression  36  and the second depression  32 , and any intermediary depressions, determines the relationship of the needle  14  relative to the outer shell  16 . 
         [0038]    In another exemplary embodiment, the outer surface  21  of holder  18  further includes two intermediate depressions for selectively engaging the protrusion  50  of outer shell  16 . The first intermediate depression  31  defines a first intermediate position  33  and the second intermediate depression  35  defines a second intermediate position  37 . The second intermediate depression  35  is proximate to the second depression  32  and the first intermediate depression  31  is distal to each of the second intermediate depression  35  and the second depression  32 . The outer shell  16  in an extended position and the second position  34  corresponds to the outer shell  16  in a retracted position. 
         [0039]    Protrusion  50  of outer shell  18  is movable between the first  38  and second  34  positions. The first position  38  corresponds to the outer shell  16  in an extended position and the second position  34  corresponds to the outer shell  16  in a retracted position. In another exemplary embodiment, the first intermediate position  33  and second intermediate position  37  both correspond to the outer shell  16  in a partially retracted position where only a portion of needle  14  is visible. When protrusion  50  is engaged in the second intermediate depression  35 , a greater portion of needle  14  is visible compared to when protrusion  50  is engaged in the first intermediate depression  31 . 
         [0040]    Referring to  FIG. 5 , a top view, partially in section, of the syringe assembly  10  is generally shown. The syringe assembly  10  further includes a spring  23  biased toward a forward end  25  of plunger  24 . This forward end  25  of plunger  24  is biased forwardly by spring  23  to resiliently hold carpule  12  in holder  18 . In one embodiment, the syringe assembly  10  is self-aspirating. 
         [0041]    Referring to  FIG. 6 , a partial sectional view of the syringe assembly  10  is generally shown. The holder  18  further includes a channel  40  for continuously engaging protrusion  50  of outer shell  16 . The channel  40  is formed longitudinally along at least a portion of the length of holder  18 . In one embodiment, the outer shell  16  further includes at least one protuberance  27  engaging channel  40 . The engagement of protuberance  27  in channel  40  prevents the rotation of holder  18  within outer shell  16 . In another embodiment, the first depression  36  and second depression  32  are formed in channel  40 . In a further embodiment, the outer shell further includes a grip  17  that covers a portion of the proximal end  48  of the outer wall  29  of the outer shell  16  for ease of holding the syringe assembly  10  by a user. 
         [0042]    Referring to  FIG. 7 , an isometric view of a portion of an embodiment of the syringe assembly showing a section of an inner wall of the outer shell is generally shown. A gap  19  is provided at the proximal end  48  of outer shell  16  to allow for expansion of the outer shell  16 . The outer shell further comprising an opening  47  for receiving a needle  14 . In a further embodiment, the inner surface  28  of outer shell  16  including a conduit  60  extending from the proximal end  48  to the carpule  12  for allowing self-aspiration of the syringe assembly  10 . 
         [0043]    In one embodiment, a portion of a distal end  47  of outer shell  16  is textured to obscure viewing of needle  14 . In another embodiment, a portion of the proximal end  48  of outer shell  16  is coated or otherwise covered with a polymeric material that is similar to that material found on toothbrushes. 
         [0044]    In another embodiment, the syringe assembly of the present invention can be manufactured by methods known to those skilled in these arts. More particularly, the outer shell  16  can be injection molded in two identical pieces that are then joined together or in a single mold. In a further embodiment, each of holder  18  and plunger  24  may also be injection molded. 
         [0045]    In one embodiment, the outer shell  16  is constructed from suitable flexible materials such as plastics, metals, or other materials known in the art that. The proximal end  48  of the outer shell  16  may be temporarily deformed to enable the proximal end  48  to be biased toward the holder  18 . 
         [0046]    The syringe assembly  10  to load the syringe assembly  10  with a carpule, a user pulls plunger  24  away from the proximal end  48  of outer shell  16  such that the plunger  24  is fully extended, spring  23  is in tension, and aperture  15  of holder  18  is exposed for loading a carpule  12  in holder  18 . Once the carpule is loaded, the plunger  24  slides forward toward the proximal end  48  of outer shell  16 , spring  23  is biased toward the carpule holding the carpule resiliently in place in holder  18 , and the protrusion  50  is engaged in the first depression  36 . In another embodiment, the syringe assembly  10  may be loaded with a carpule using methods known to persons skilled in the art. 
         [0047]    In use, the syringe assembly once loaded with a carpule  12 , the outer shell  16  is in an extended position such that needle  14  is in a retracted position and is completed covered by the outer shell  16  as shown in  FIG. 2 , and the protrusion  50  of outer shell  16  is engaged in the first depression  36  of holder  18 . This is the first position  38 . 
         [0048]    The user then applies pressure to the plunger  24 . The plunger  24  and holder  18  move as a unit relative to outer shell  16 , and the protrusion  50  springs out of the first depression  36 , and the holder  18  and plunger  24  together slidably engage the outer shell  16  sliding toward the distal end of outer shell  16  until protrusion  50  engages a first intermediate depression  31 . In this first intermediate position  33  a portion of needle  14  is visible and the outer shell  16  is partially retracted. Pressure continues to be applied by the user and protrusion  50  springs out of the first intermediate depression  31 , the holder  18  and plunger  24  continue to slide as a unit in the outer shell  16  until protrusion  50  engages a second intermediate depression  35 . In this second intermediate position  37 , a greater portion of needle  14  is visible and a greater portion of the outer shell  16  is partially retracted. Pressure continues to be applied by the user and protrusion  50  springs out of the second intermediate depression  35 , the holder  18  and plunger  24  together continue to slide as a unit in outer shell  16  until protrusion  50  then engages the second depression  32 . In this second position  34 , the outer shell  16  is in a retracted position such that needle  14  is in an extended position as shown in  FIG. 1 . 
         [0049]    Upon reaching the second depression, the user applies further pressure to plunger  24 . The plunger  24  slides in holder  18  and the forward end  25  of the plunger  24  selectively engages the container  12 . The continued pressure by the uses moves the plunger  24  to a dispensing position and urges the contents of the carpule  12  from the carpule  12 , through the needle  14 . 
         [0050]    The above-described embodiments have been provided as examples, for clarity in understanding the invention. A person of skill in the art will recognize that alterations, modifications and variations may be effected to the embodiments described above while remaining within the scope of the invention as defined by the claims appended hereto.