Abstract:
A disposable aspirating syringe for dental medicine having the ability to accept single use or disposable drug cartridges. The syringe offers a retractable needle and a break-away plunger to facilitate disposal and increase safety.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to non-reusable aspirating safety syringes with retractable needles for use, for example, in the dental, medical or veterinary arts. 
     Disposable syringes with retractable needles are desirable because they are economical and hygienic. Retractable needles are especially desirable because they greatly reduce accidental sticking of needles in caregivers and patients. Further, the retractable nature of needles is desirable because they provide a visual aid indicating prior use. In addition, many retractable designs make reuse of the needle and syringe impossible. 
     Of particular importance in the dental arts is a syringe that may be used to aspirate. Aspiration is the practice of retracting a syringe plunger in order to draw fluids from the patient&#39;s body into the drug cartridge so that the caregiver may verify whether a vein was mistakenly invaded. The desirable characteristics of aspirating syringes and other necessary functions are extolled in U.S. Pat. No. 6,068,618 and incorporated herein by reference. 
     However, in the dental arts, for example, medication and anesthetic are often consumed in disposable vials or cartridges. The prior art describes re-usable syringes that are adapted to receive such single use, disposable cartridges. But, there are inherent drawbacks to this method of consuming dental drugs. 
     First, traditional disposable syringes are generally inexpensive and simple in design. Further, some can retract a needle after use, thus facilitating proper disposal. But, they cannot accommodate common single use disposable drug cartridges. 
     To overcome some of these drawbacks, a re-usable syringe was developed. Constructed of a durable material, such as chrome plated brass or stainless steel, such syringes readily accepted the disposable cartridges and the syringes were adapted for use as aspirating syringes—having a modified plunger with a handle feature that facilitated both dispensing drugs and aspiration. Although this type of syringe is very successful, it too has drawbacks. For example, the durable construction from brass or stainless steel is costly. Second, the re-use of the syringe necessitates a relatively expensive sterilization procedure and additional equipment. Further, the re-useable syringe is susceptible to re-use prior to proper sterilization, which may promote the spread of germs, viruses and other contagious diseases. 
     In addition, the avoidance of needle sticks (that is the in advertent pricking of a patient or caregiver with a needle) when using re-useable syringe assemblies is not adequately addressed in the prior art, because many of such previous devices do not have the ability to retract a needle after use. In the current designs of most re-usable syringe assemblies, the needle must be removed by hand. This greatly increases the risk of an accidental needle stick. 
     It is therefore desirable to have a novel disposable syringe that incorporates the advantages of an economical syringe and the safety features of a retractable needle, with such characteristics as captured in reusable syringes, such as the ability to aspirate and accommodate disposable cartridges. 
     SUMMARY OF THE INVENTION 
     Generally, the novel syringe features a retractable needle. The syringe includes a plunger, a barrel and a body. The body is, for example, generally tubular and hollow and has a longitudinal opening. On the exterior of the body at a proximal end, there is a finger grip feature, which is known in the art. This feature is for the comfort and convenience of the caregiver, and the syringe would work in substantially the same manner with or without such a contoured finger grip. The syringe body may also include a handle at the proximal end. This feature could assist with aspiration and control of the syringe. At the oppositely spaced distal end of the body is a nozzle feature. The nozzle feature is adapted to receive the barrel assembly. 
     As mentioned, the body has a longitudinal opening. The longitudinal opening easily accepts a disposable cartridge of fluid drug, as known in the art. However, a cartridge may be successfully introduced to the syringe body by placing the cartridge in either a proximal or distal open end, in the alternative. 
     In lieu of a known cartridge, an alternative novel capsule may be used, as described subsequently. In either instance, the cartridge or the novel capsule may be inserted in the longitudinal opening, or introduced at one open end of the body. Once positioned, the cartridge or capsule is engaged by the plunger at one end and the barrel at a second end, for example. The barrel is adapted to pierce a flexible membrane or diaphragm of the capsule or cartridge. 
     The barrel has a feature that protrudes from a central body. The protrusion has a barb. The barb and protrusion are hollow, allowing fluid communication between the capsule or cartridge and the barrel assembly. 
     At an end opposite from the barbed protrusion is a threaded member, for example, that is adapted to receive a needle assembly, as known in the art. It is contemplated and within the scope of the present invention for the needle assembly to attach with a LUER® lock or any other locking mechanism. The needle assembly may be a double piercing needle, as typically used with re-useable syringe assemblies of the prior art. Alternatively, the needle assembly may be a single piercing construction as is common with known disposable, single use needles. 
     Also included with the barrel is a seal. The seal rests around a peripheral surface and is in sealing contact with the nozzle of the syringe body. For example, an o-ring may be used to removably seal the barrel and the body. 
     The nozzle of the syringe body has a feature that retains the barrel in fixed position, preventing the barrel from being dislodged from the distal end, but permitting the barrel and needle assemblies to be retracted after use and withdrawn toward the plunger end of the syringe body, and drawn entirely within the capsule. 
     The syringe assembly also has a plunger that is slidebly received in the hollow tubular body. The plunger has a feature that engages the top plug of the drug cartridge or capsule. The plunger may also include a looped member, as is used in the art to facilitate the use of the needle to aspirate. The plunger also has a breakaway feature, for example, a score line, so that a used plunger may be fractured after use. This will allow a more compact disposal of the invention. 
     As mentioned, a known disposable fluid drug cartridge may be used with this novel syringe. In such a case, a double piercing needle may be attached to the barrel assembly. One end of the needle would pass through the barrel and the barbed protrusion would pierce the cartridge diaphragm. After use, the double piercing needle would be unscrewed from the barrel. Then the syringe assembly and cartridge would be discarded normally. Alternately, a single piercing needle may be used. It would be attached to the barrel assembly. After use, the entire barrel along with the needle would be withdrawn and captured entirely within the capsule. 
     Therefore, the present invention alleviates many of the aforementioned deficiencies in the prior art. Insodoing, it is therefore one object of the invention to provide an aspirating safety syringe with a retractable needle. Moreover, it is an object of the present invention to provide a disposable aspirating syringe. 
     It is a further object of the invention to provide a syringe that can receive disposable, single use drug cartridges. 
     It is another object to provide such a disposable syringe that is economical to manufacture and dispose. 
     Another object of the invention is to increase safety by providing a visual means to indicate that a syringe has been used and also to reduce the probability of inadvertent needle “sticks.” 
     Yet another object of the invention is to provide a novel disposable cartridge for drugs that can be used with the novel disposable aspirating syringe. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a novel aspirating disposable syringe with plunger in a collapsed position. 
     FIG. 2 is a perspective view of an aspirating disposable syringe showing, in assembly format, the relation of a single use drug cartridge and needle assembly thereto. 
     FIG. 3 is a sectional view, taken along the longitudinal axis of a syringe assembly and its components are shown in an exploded assembly view, the components of the assembly comprise a needle assembly, a barrel with protruding barb, an exploded capsule assembly, a syringe body and a plunger 
     FIG. 4 is a sectional view of a syringe assembly showing the needle attached thereto and the plunger in a fully extended position. 
     FIG. 5 is a sectional view of a syringe assembly showing a capsule inserted therein and the plunger engaging the capsule. 
     FIG. 6 is a sectional view of a syringe assembly with the plunger partially compressed and the capsule has been penetrated by the protruding barb of the barrel assembly. 
     FIG. 7 is a sectional view of a syringe assembly with the plunger mostly compressed and engaging the barbed protrusion of the barrel assembly. 
     FIG. 8 is a sectional view of a syringe assembly with the plunger in the extended position after use. The needle assembly is retracted and contained wholly within the capsule. 
     FIG. 9 is a detailed sectional view of the nozzle region of the syringe body depicting the retention of the barrel therein including the sealing member. 
     FIG. 10 is a detailed profile view of the plunger showing a score line. 
     FIG. 11 is a detailed profile view of the barrel adapted for a double piercing needle. 
     FIG. 12 is cross section of the capsule showing, in assembly format, the plug and plunger sealing means. 
    
    
     DETAILED DESCRIPTION 
     Although the disclosure hereof is detailed and exact to enable those skilled in the art to practice the invention, the physical embodiments herein disclosed merely exemplify the invention which may be embodied in other specific structure. While the preferred embodiment has been described, the details may be changed without departing from the invention, which is defined by the claims. 
     Like parts are numbered alike in all figures. 
     Referring now to the drawings, specifically FIG. 1, the syringe assembly  20  of the present invention is shown in a preferred embodiment. The syringe body  22  has a longitudinal opening  24 , which is adapted to receive a single use drug cartridge (discussed subsequently). At one end of the body  22  the syringe  20  tapers to a nozzle  28 , extending from the nozzle  28  is a portion of the barrel  40  namely, the threaded member  46 . At an opposite end of the body  22 , there is, for example, a contoured feature for a finger grip  26 . Adjacent to the grip  26 , a handle  27  may be included. Inserted in the body  22  is a plunger  30 . The plunger may have a looped member  32  to facilitate aspiration, for example. The plunger  30  has a slender shaft  36  that connects the looped member  32  to an opposite spaced grippers  38 . The shaft  36  may have a score line  34 , which would facilitate breaking of the shaft  36  to aid disposal. The grippers  38  are adapted to be inserted in the capsule  60  (not shown in this figure, discussed subsequently). In FIG. 1, the syringe  20  is shown in a partially extended position, emulating the condition prior to use. 
     Referring now to FIG. 2, the syringe assembly  20  of the present invention is shown in relationship to an attachable needle  50  and an insertable capsule  60 . The capsule  60  may be, for example, of the single use disposable type cartridge of the prior art or, alternatively, a novel capsule  60  (discussed subsequently). The cartridge or capsule  60  may be inserted through the longitudinal opening  24  of the syringe body  22 , for example. The capsule may have a diaphragm  62  that seals one end of the capsule  60  and may be pierced by barb  44  of the barrel  40 . At an opposite end of the capsule  60  there is a plug  64  that seals the capsule  60 . The plug  64  permits the grippers  38  of the plunger  30  to invade, while maintaining the seal with the capsule  60 . The plug  64  and diaphragm  62  may be unique in geometry, or, alternatively, they may be of the same geometry, albeit separate parts. In a preferred embodiment the diaphragm  62  and plug  64  are molded from a rubber or similar synthetic compound, as generally known in the art, and share similar geometry, for example. 
     In one embodiment, as shown in FIG. 2, a means for inserting the capsule  60  in a syringe assembly  20  may include, for example, a longitudinal opening  24 . However, the cartridge may be introduced, alternately, for example, through the proximal open end of the body  22 . 
     Still referring to FIG. 2, also shown is a needle assembly  50 . Depicted in FIG. 2 is a single piercing needle  52  as is commonly known in the art. However, a double piercing needle  58  (see FIG. 11) could work just as well and in a similar manner. The needle  50  is attached to the barrel  40 . The needle  50  may be, for example, screwed on to the threaded member  46  of the barrel  40 . Alternatively, a common bayonet type fastening means, such as a LUER® lock mechanism, as known in the art, may be used to couple the needle to the barrel (not shown). Also visible in FIG. 2 is the barb  44  on the end of the protrusion  42 , which are part of the barrel (partially hidden from view). 
     Again referring to FIG. 2, the plunger  30  is shown in a fully retracted or withdrawn position. In this position, the syringe assembly  20  is ready to receive a single use disposable drug cartridge (not shown) or capsule  60 . 
     Now referring to FIG. 3, an exploded view of a longitudinal cross section of the various components and assemblies that comprise a preferred embodiment of the present invention is shown. A needle assembly  50 , shown here as a single piercing needle  52  attaches to the threaded member  46  of the barrel  40 . Prior to attaching the needle  50  to the barrel  40 , the barrel  40  may, preferably, be inserted into the nozzle portion  28  of the syringe body  22 . The barrel  40  rests inside the body  22  at the nozzle  28  so that the threaded member  46  of the barrel  40  extends outside the syringe body  22 . To seal and assist in retention of the barrel  40  within the nozzle  28 , a sealing member  48 , such as an o-ring, may be located on a peripheral feature of the barrel  40 . 
     Still referring to FIG. 3, it is understood that the plunger  30  may be preferably inserted in the syringe body  22  prior to use. In one embodiment, the plunger may be pre-assembled to the body  22  at a remote manufacturing facility, for example. The plunger  30  slideably engages the interior of the body  22 . At one end of the plunger  30  there is a looped member  32 , as depicted in FIG.  3 . The looped member  32  may assist the user in performing aspiration, as commonly used in the art of dental medicine. Alternative handle like features may be used with similar results. The looped member  32  is coupled to a shaft  36 , which is adapted to slide within the interior of the syringe body  22 . At an end opposite the handle  32  and also coupled to the common shaft  36  is a gripper  38 . The gripper  38  is adapted to engage a feature on the capsule  60  (discussed subsequently). 
     Located in a predetermined position on the shaft is a line of weakness, called a score line  34 . This line  34  is included on the shaft  36  to create a stress concentrating area so that the shaft  36  will fail in a predetermined position given a predetermined applied force. In a preferred embodiment the force required to break the shaft  36  at the score line  34  is that of an average caregiver&#39;s hand strength. The score line  34  is intended to assist the caregiver or user of the syringe in disposing of a used syringe assembly  20 . Thus, the ordinary caregiver or user may simply break the shaft  36  at the score line  34  and easily discard the spent syringe. It will be understood that by breaking the plunger  30  from a syringe body  22  will reduce the amount of space required for disposal. However, the score line  34  is not essential to the performance of the syringe  20 . 
     In addition, the plunger  30  may include a biasing means (not shown). It is understood that such a device may be used to enable the plunger  30  to self-aspirate. 
     Still referring to FIG. 3, a capsule  60  is shown having a plug  64  and a diaphragm  62 . The plug  64  is adapted to receive the aforementioned gripper  38  of the plunger  30 . The gripper  38  penetrates an outer surface of the plug  64 . With the gripper  38  embedded in the plug  64 , the plug  64  becomes coupled to the gripper  38 . Thus, when the plunger  30  is depressed, the plug  64  is forced to travel in the direction of the plunger  30 . Accordingly, if the plunger  30  reverses its direction of travel, the plug  64  will reverse as well, which provides the aspirating feature of this invention. 
     It should be noted that a preferred embodiment of the aspirating syringe  20  uses a novel capsule  60 . However, existing drug cartridges for single use, as known in the art would work as well. Instead of the gripper  38  engaging a plug  64 , the gripper  38  simply pushes on the stopper (not shown) of prior art cartridges (not shown). 
     Again referring to FIG. 3, a preferred embodiment shows a plug  64  and a diaphragm  62 . The diaphragm  62  and the plug  64  both may, preferably, seal the capsule  60 . Also, the diaphragm  62  is adapted to be pierced by either a prior art needle, such as a double piercing needle  58  (see FIG.  11 ), or by the barb  44  on the protrusion  42  of the barrel  40 . Thus, it may be desirable to form, by a molding process, for example, the plug  64  and diaphragm  62  from the same material and in substantially the same geometry. 
     Referring now to FIGS. 4-8 inclusive, a sequence of operations may be observed demonstrating a preferred use of the present invention. FIG. 4 represents the syringe assembly  20  in a state that is ready for introduction of a single use drug capsule  60  or prior art disposable drug cartridge. The plunger  30  is fully retracted. The barrel  40  is installed in the nozzle  28  and a needle  50  is attached to the protruding threaded member  46  (hidden from view). In this sequence of figures, the needle  50  shown is a single piercing needle  52 . However, a double piercing needle  58  (see FIG. 11) would operated in substantially the same manner. 
     A capsule  60  is inserted via the longitudinal opening  24  (not shown) on the syringe body  22 . FIG. 5 depicts the engagement of the plunger  30  to the capsule  60 . The gripper  38  at one end of the shaft  36  of the plunger  30  has penetrated the plug  64  of the capsule  60 . Note the relative displacement of the plunger  30  assembly to the body  22 . At the opposite end of the capsule  60 , the barb  44  at the end of the protrusion  42  of the barrel  40  has not yet penetrated the diaphragm  62 . 
     Next, the diaphragm  62  is pierced by the barb  44 , as shown in FIG.  6 . The barb  44  is forced through the diaphragm  62  so that the barb  44  is in fluid communication with the drug contained inside the capsule  60 . 
     As the plunger  30  continues to travel toward the body  22 , the capsule  60  remains in fixed position, while the plug  64  moves with the plunger  30 . In this manner, fluid is forced from the interior of the capsule  30  through the hollow interior of the barb  44  and protrusion  42 . Thus, the barrel  40  acts as a conduit for the fluid from the capsule  60  to the needle assembly  50 . 
     As FIG. 7 shows, when the plug  64  travels to a fully entrenched position in the capsule  60 , the barb  44  is forced through the plug  64  and is captured by the gripper  38  of the plunger  30  in a manner that is understood in the art. 
     Accordingly, as FIG. 8 shows, as the plunger  30  is retracted after use, the plug  64  and diaphragm  62  are brought along. Further, since the gripper  38  is coupled to the barb  44 , the entire barrel  40  retracts along with the needle  50 . When the plunger  30  is fully retracted, the needle  50  rests inside the capsule  60 . At this point the syringe  20  may be discarded in a safe manner. Alternatively, the plunger  30  may be intentionally broken at the score line  34 , thus two pieces may be discarded in a more compact format. 
     FIG. 9 highlights an embodiment of the syringe body  22 . In order to prevent the barrel  40  from escaping from the end of the nozzle  28  in an undesirable direction, a retaining flange  23  is included. The flange  23  is dimensioned so to freely pass the threaded member  46  of the barrel and needle  50  through an aperture of the nozzle  28  when it is desired to retract the needle  50 . Accordingly, the barrel  40  is adapted to use the flange  23 . 
     FIG. 9 also highlights the hollow interior of the barrel  40 , along with the fluid communication passage that connects the barb  44 , the protrusion  42  and the needle assembly  50 . 
     FIG. 10 highlights, in a detail view, the score line  34  on the shaft  36  of the plunger  30 . 
     FIG. 11 depicts an envisioned embodiment that uses a known double piercing needle  58 . The double piercing needle  58  would be a part of the needle  50  which fastens to the barrel  40 . A means of fastening may include, for example, mating threads on the needle  50  and the threaded member  46  of the barrel  40 . The double piercing needle  58  may extend, for example, through a portion of the protrusion  42 . Alternately, the needle  58  may extend beyond the barb  44  (not shown). 
     FIG. 12 shows a novel capsule  60  for a fluid, such as a drug or anesthetic. Single use cartridges, also called disposable cartridges or capsules, are contemplated. Such a capsule  60  is generally a hollow tubular body  61  and may be constructed from glass for example or what is commonly known as plexi-glass. The tube  61  has two oppositely spaced open ends. Each end having a flexible sealing member  63  that provides a hermetic seal with the tube walls, thus preventing the escape of any fluid. At one end, the sealing member  63  may consist of a diaphragm  62  which would have the additional characteristic of being piercable by either a double piercing needle  58  (see FIG.  11 ), or by a barb  44  (see FIGS. 1-8) as previously disclosed herein. At a second end, the sealing member  63  may consist of a plug  64 , which would be adapted to receive a plunger  30  (FIGS. 1-8) as previously described, or by a plunger as is known in the prior art. 
     The foregoing is considered as illustrative only of the principles of the invention. Furthermore, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described. While the preferred embodiment has been described, the details may be changed without departing from the invention, which is defined by the claims.