Patent Publication Number: US-2009234284-A1

Title: Safety Syringe Device

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a safety syringe device, and more particularly, to a syringe device having a needle assembly capable of being retrieved into the syringe tube, and with better operational friction force and structural condition when its push rod and needle seat are combined, and having an easily fabricative structure. 
     2. Description of the Prior Art 
     Keeping in pace with level up of the scientific and medical technology, people have been more gradually aware of importance of good health, and pay more and more attention to the use of medical equipment. Improper treatment and disposal of used medical instruments, for example, the syringe needle intrusive to the human body is handled with less care, may cause severe injury to both the patient and medical personnel. 
     Nowadays, repeated use of the syringe needle and accidental puncturing of the skin with a used syringe needle during after-treatment are most problematic. Accordingly, the used syringe device must be thoroughly treat to an extent that it can never be used again, while during the treatment, the working personnel should be well protected not to be hurt by such a used syringe device. For solving these problems, the inventor of the present invention has contrived several safety syringe devices and actually acquired some of the related patents. In a bid to get better and simpler structure and attain optimal frictional force and compactness among component parts of the syringe device, he herein goes to great length of intensive research based on many years of experience acquired through professional engagement in the manufacturing of related products with continuous efforts for improvement finally come up with an improved structure of the present invention. 
     SUMMARY OF THE INVENTION 
     The main object of the present invention is to provide a safety syringe device with a needle stem which is retrieval to the syringe tube after completion of injection by turning back to separate in the manner of breaking an exposed push rod at its neck where the diameter is reduced. 
     This safety syringe device with a simple, compact and easy to fabricate structure is composed of a syringe tube, a push rod, a needle seat, a needle stem and a needle base. 
     Inside the syringe tube there forms a medicine compartment provided with an interior threaded section and a positioning screw thread at its front end thereof, while a salient guillotine fringe is formed along the interior surface at the rear end. 
     The push rod which being inserted into the syringe tube has a top pusher of reduced diameter with a jut at its tip on the top portion thereof, and several billet like aligning clogs are disposed at a equal pitch around the lower exterior circumference of the top pusher. A guide surface sloping down to both sides is formed at the front end of each clog. Each clog has a ferrule underneath with a ring provided between the clog and the ferrule. 
     The front end of the needle seat is formed into a core bit of reduced diameter with a central path longitudinally passing through, and a stopper is provided in the central path, while the rear end of the needle seat is communicated with an accommodation cavity with several fixing blocks provided along the accommodation cavity, between two adjacent fixing blocks there is formed a barrier space. Around the exterior circumference of the accommodation cavity in the needle seat there are formed an exterior threaded section and a recessed annular groove. The exterior threaded section is to mate the interior threaded section formed in the syringe tube such that the needle seat can be tightly screw combined with the syringe tube. 
     By screw engaging the needle seat with the syringe tube, the needle stem can be set on the core bit, afterwards turn the positioning screw thread portion to tighten the whole structure, the safety syringe device is ready for operation by delivering the liquid drug from the medicine compartment in the syringe tube to the needle stem via the accommodation cavity and central path of the needle seat. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawings disclose illustrative embodiments of the present invention, which serve to exemplify the various advantages and objects hereof, and are as follow: 
         FIG. 1  shows an exploded view of the safety syringe device in a first embodiment of the present invention; 
         FIG. 2  is a sectional view of  FIG. 1 ; 
         FIG. 3  is an illustrative view showing the push rod is ready in the position to be pushed form the rear end of the syringe tube to perform injection; 
         FIG. 4  is a three dimensional view of the push rod in a first embodiment; 
         FIG. 5  is a three dimensional view of the needle seat in a first embodiment; 
         FIG. 6  is a sectional view showing the push rod and needle stem are ready in the position to perform injection; 
         FIG. 7  is a sectional view showing the needle base is assembled on the needle seat for the needle stem ready to perform injection, and a partially enlarged view is provided for illustrating assembly manner; 
         FIG. 8  is the factionary perspective view of  FIG. 6 ; 
         FIG. 9  is an illustrative view wherein the push rod is turned reversely to draw the needle seat downwards such that its exterior threaded section is liberated from the positioning screw thread of the syringe tube; 
         FIG. 10  is a schematic view showing the state that the needle seat and needle stem is remained in the syringe tube after breaking the neck portion of the push rod, and then the needle base is reversely inserted into the syringe tube where the needle stem penetrates through; 
         FIG. 11  is an exploded three dimensional view of the syringe tube in a second embodiment; 
         FIG. 12  is an assembly view of  FIG. 11 ; and 
         FIG. 13  is a sectional view of the needle seat in a third embodiment assembled with the syringe tube shown in  FIG. 11 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to  FIG. 1  through  FIG. 8 , the safety syringe device of the present invention comprises a syringe tube  1 , a push rod  2 , a needle seat  3 , a needle base  4  and a needle stem  41 . 
     The structure of the syringe tube  1  is substantially identical to those previously disclosed by the present inventor. It is essentially a cylindrical structure with a medicine compartment  11  formed inside at the center portion. At the front end inside the medicine compartment  11  there is a portion of reduced diameter having an interior threaded section  12  and a positioning screw thread  13 , while at the rear end there is a salient guillotine fringe  14  formed along the interior surface thereof. At one end of the syringe tube  1  there is provided a pusher strip  15  to be pushed with the thumb. 
     Referring again to  FIG. 4  and  FIG. 5 , the push rod penetrating through the syringe tube  1  has a top pusher  21  of reduced diameter with a jut  22  at its top portion thereof, whereas the diameter of the jut  22  is slightly larger than that of the top pusher  21  on its top. Several billet like aligning clogs  23  are disposed at an equal pitch around the lower exterior circumference of the top pusher  21 . A guide surface  24  sloping down to both sides is formed at the front end of each clog  23 . Under the clog  23  there is a ferrule  25  with a ring  26  provided between the clog  23  and the ferrule  25 . The ring  26  presses on the wall of the syringe tube  1  where the medicine compartment  11  is formed. 
     Under the ferrule  25  there is a neck portion  27  of reduced diameter in order to leave the section above it in the syringe tube  1  by twisting the push rod  2  after injection is over, and under the neck portion  27  there are several elongated ribs  28  whose terminal are attached with a pusher strip  29  to be pushed with thumb, an arrow head indication is marked at least on one side surface of the pusher strip  29 . 
     The front end of the needle seat  3  is formed into a core bit  31  of reduced diameter with a central path  32  longitudinally passing through and a stopper  38  is provided in the central path  32 , while at the rear end of the needle seat  3  there is an accommodation cavity  33  formed in communication with the central path  32 . Several fixing blocks  24  are provided at an equal pitch around the surface of the accommodation cavity  33 , between two adjacent fixing blocks  34  there is formed a barrier space. Around the exterior circumference of the accommodation cavity  33  in the needle seat  3  there are formed an exterior threaded section  35  and a recessed annular groove  36 . The exterior threaded section  35  is to mate the interior threaded section  12  formed in the syringe tube  1  such that the needle seat  3  can be tightly screw combined with the syringe tube  1 . A collar  37  is hooped around the recessed annular groove  36 . Both threaded sections  35  and  12  employ square screw thread. 
     The needle stem  41  is inserted to or adhered to the needle base  4  and its bottom edge is formed into a guide flange  42 , when the needle seat  3  comes to meet the interior threaded section  12  of the syringe tube  1 , both the needle base  4  and the needle seat  3  can be set on the core bit  31  and fixed there, and the needle seat  3  and the needle stem  41  can be fixed by turning the positioning screw thread  13 . by so, the medicine contained in the medicine compartment  11  in the syringe tube  1  can be delivered from the accommodation cavity  33  and flow through path  32  and needle stem  41  into the patient body. The bottom of the fixing block  34  is configurated into a sloping surface down to two sides from its center portion. 
     A conical needle protector  43  encloses the needle base  4  in the syringe tube  1  so as to avoid exposing the point of needle stem  41  that may accidentally puncture the human skin. 
     Referring to  FIG. 3 , when in using the safety syringe device constructed as such, at first put the needle seat  3  into the medicine compartment  11  of the syringe tube  1 , and push the push rod  2  from the rear of the needle seat  3  to make its aligning clogs  23  trapped in the barrier spaces each formed between two adjacent fixing blocks  34  in the needle seat  3  thereby completing the assembly. Then continue to push the needle seat  3  onward with the push rod  2  until its core bit  31  reaches the positioning screw thread  13  of the syringe tube  1  to combine its exterior threaded section  35  with the positioning screw thread  13  such that the needle seat  3  can go onward by turning until its collar  37  is detained at the wall surface of the interior threaded section formed in the syringe tube  1 . At this moment the ring  26  of the push rod  2  pressed around the inner wall surface of the syringe tube  1  so as to ensure the medicine compartment  11  perfectly hermetical. Afterwards needle base  4  with its needle protector  43 , can be settled on the core bit  31  of the needle seat  3  by screw combining the guide flange  42  of the needle base  4  with the interior threaded section  12  such that the needle base  4  is able to revolve along the needle seat  3  and brings its sloped surface to fit on the core bit  31 . 
     The operation to draw the medicine is identical to that of the traditional syringe device. After taking off the needle protector  43  and inserting the needle stem  41  into the medicine bottle (not shown), draw back the push rod  2  to absorb the medicine into the medicine compartment  11 . This action can be reliably performed by reason that the needle seat  3  is firmly assembled with the syringe tube  1  by screw combining the exterior threaded section  35  and the positioning screw thread  13 . After finishing injection, continue to push the push rod  2  forwards until the top end of the stopper  38  provided on the core bit  31  detains its jut  22 . 
     Afterwards turn the push rod  2  in the reverse direction to drive the needle seat  3  retreat along the helical route of the positioning screw thread  13  so as to liberate its exterior threaded section  35  out of the detention of the positioning screw thread  13 ,and also liberate the entire needle seat  3  out of the detention of the interior threaded section  12  of the syringe tube  1  thereby hiding the needle seat  3  together with the needle stem  41  in the medicine compartment  11  of the syringe tube  1 . As soon as the neck portion  27  of the push rod  2  has retreated to face against the guillotine fringe  14  of the medicine compartment  11 , the guillotine fringe  4  can sever the neck portion  27  by shaking the push rod  2 ; the needle stem  41  is left in the syringe tube  1  (see  FIG. 10 ). After that reversely insert the needle protector  43  into the interior threaded section  12  and throw them into the disposal container. 
     Referring to  FIG. 11  and  FIG. 12 , in this second embodiment, the safety syringe device also comprises a syringe tube  1 , a push rod  2  a needle seat  3 , a needle stem  41  and a needle protector  43 . The only difference from the first embodiment lies in that its syringe tube  1  only contains the positioning screw thread  13  but has no interior threaded section  12 , however other structural and operational features remain the same. 
     Referring to  FIG. 13 , in this third embodiment, similar to two previous embodiments, the safety syringe device comprises a syringe tube  1 , a push rod  2 , a needle seat  3 , a needle stem  41  and a needle protector  43 . The difference from the previous embodiments lies in that its syringe tube  1  only contains the positional screw thread  13  but has no interior threaded section  12 , and the push rod  2  is not equipped with the top pusher  21 , it has only the jut  22 . The needle stem  41  is directly affixed to one end of the needle seat  3  without employing the core bit  31  and path  32 . Around the surface of the accommodation cavity  33  of the needle seat  3 , there are provided several fixing blocks  34  disposed at an equal pitch and a stopper  38 . Other structural and operational features of the component parts push rod  2 , needle seat  3 , needle stem  41  and needle protector  43  remain the same as the previous embodiments. 
     It emerges from the description of the above embodiments that the invention has several noteworthy advantages, in particular: 
     (1) The jut  22  of the push rod  2  can be detained by the stopper  38  of the core bit  31  that enables the medicine in the syringe tube  1  to be completely injected into the patient body without wasting. 
     (2) The used needle stem  41  is restored in the syringe tube  1  without the worry of exposing to puncture anyone&#39;s skin. All used component parts including syringe tube  1 , push rod  2 , needle seat  3  and needle stem  41  can not be restored for reuse thereby the medical security is assured. 
     (3) The needle seat  3  and the syringe tube  1  are engaged with each other with square screw threaded sections  35  and  12  that ensures reliable structural security and improves yield of fabrication of the syringe device. 
     (4) The provision of fixing blocks  34  with intermediate barrier spaces to confine the aligning clogs  23  of the push rod  2  contributes to supplying an appropriate frictional force when operating the device. The ring  26  of the push rod  2  performs the function of effectively maintaining perfect hermetical state in the medicine compartment  11  without the fear of leaking medicine. 
     Those who are skilled in the art will ready perceive how to modify the invention. Therefore the appended claims are to be construed to cover all equivalent structures, which fall within the true scope and spirit of the invention.