AU2003248445B2

AU2003248445B2 - Retractable safety syringe with a soft piston

Info

Publication number: AU2003248445B2
Application number: AU2003248445A
Authority: AU
Inventors: Peng-Chieh Wu
Original assignee: Life Shield Products Inc
Current assignee: LIFE-SHIELD PRODUCTS Inc
Priority date: 2002-10-16
Filing date: 2003-09-29
Publication date: 2005-07-07
Anticipated expiration: 2023-09-29
Also published as: JP2004136088A; AU2003248445A1; CA2444988A1; TW571750U; CA2444988C; ZA200307841B

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Applicant(s): LIFE-SHIELD PRODUCTS, INC.

Invention Title: RETRACTABLE SAFETY SYRINGE WITH A SOFT PISTON The following statement is a full description of this invention, including the best method of performing it known to me/us: /4 TITLE: RETRACTABLE SAFETY SYRINGE WITH A SOFT PISTON BACKGROUND OF THE INVENTION 1. Field of the invention The present invention is related to a retractable safety syringe with a soft piston; and especially to such a syringe in which the piston is made of elastic material in order that when in drawing in and injecting medicine, the front end face of the piston can be pushed to the top end of the cylindrical barrel of the syringe to allow accurate taking out of the medicine following the indicating scale marks and pressing the medicine out stably; and after injecting, the piston can be deformed by pressing, so that a connecting piece or an activating piece provided on a plunger can connect or activate a retractable mechanism provided on a needle set, and the needle set can be retracted into the cylindrical barrel. The syringe suits various cylindrical barrels of syringes or similar structures.

2. Description of the Prior Art Since the medical science was widely developed, medicine injection with syringes has been the fastest and most effective way of treatment, and it is widely adopted in the medical field. However, syringes are generally discarded after use, it becomes the main point of designing for the goal of preventing accidental stabbing and infecting medical workers in dealing with waste syringes, and the goal of reducing the volumes of discarded syringes. Thereby, various retractable safety syringes have been developed.

Referring to Fig. 1 showing the structure of a conventional manual retractable safety syringe, wherein a plunger 10 can be pulled or pushed in a cylindrical barrel the plunger 10 is provided on the front end thereof with a piston 11 and a hook portion 21, the hook portion 21 is protruded from the front end of piston 11 to form a neck portion 20 with a length therebetween. A connecting portion is if provided on the bottom of a needle set 1, when the plunger 10 is pushed forwards to the top point, the hook portion 21 can pierce into the connecting portion to form a hooking state therewith, thereby the needle set 1 can be pulled back into the cylindrical barrel The connecting portion of the needle set 1 shown in Fig. 1 is located at the center of the bottom of the needle set 1; the hook portion 21 is also located at the center of the plunger 10 to form a connecting piece. However, there are other retractable mechanisms with different pulling back modes for conventional manual retractable safety syringes. For example, the connecting portion of the needle set can be provided on the exterior surface of the base of the needle set, and the connecting piece of the plunger can be provided on the exterior surface of the plunger to be able to mutually hook or engage.

Whichever style a manual retractable safety syringe is, generally, to avoid the connecting portion of the plunger 10 to be pushed inadvertently forwards to the top point before discarding the cylindrical barrel 30 of the syringe, a measure is adopted to render the plunger 10 to be moved only when a sufficient force is exerted thereon to make connection of the connecting piece with the connecting portion "a" at the moment when the front end of the plunger 10 contacts the base of the needle set 1.

There are also automatic retractable safety syringes taking advantage of the restoring force of springs, such automatic retractable safety syringes shall have their activating pieces provided on the plungers also moved by forces to overcome resistances of predetermined values before the spring retractable mechanisms are activated.

Medical workers generally pull backwards the push rods on the rear ends of plungers of syringes to draw air into the cylindrical barrels, and then pierce needles into the medicine bottles and push forwards the plungers. The air drawn into the cylindrical barrels is injected into the medicine bottles, and the plungers are pulled back following the indicating marks to draw required amount of medicine into the cylindrical barrels. And when in injection for patients, to avoid remaining of the medicine in the cylindrical barrels, the medical workers generally will push the push rods forwards to the top points. Hence, whichever of the manual or automatic retractable safety syringes they are, during the process of injection, forces must be exerted to overcome the resistances in connecting and activating of the retractable mechanisms finally.

The above stated conventional retractable safety syringes always have following defects: 1. As shown in Fig. 1, there is a distance the length of the neck portion left between the piston 11 and the hook portion 21, thereby, when in taking injection liquid before injection, the amount of the injection medicine taken will be reduced. That is to say, the medical workers must increase the amount taken when in drawing the medicine for injection in order to avoid reducing of the treatment efficiency due to insufficiency of medicine; and if the medicine for injection is insufficient due to neglect of the medical workers, the treatment efficiency will also be lowered to influence development in treating patients.

2. When in injecting medicine for a patient with a syringe by a medical worker, by the fact that the front end of the piston 11 is unable to reach the position where the top mark indication line showing the amount of 0 ml is, while there is still injection liquid in the space between the piston 11 and the hook portion 21, the medical worker shall exert a force to push the plunger 10 to the top point, such force added abruptly during injecting may create a pain feeling of a patient.

In view of these, the inventor of the present invention studied and developed a -4- Qretractable safety syringe for drawing back a soft piston that can accurately draw in

(N

the required medicine and can stably push the plunger to the top point; and when the needle is drawn out of the body of a patient after injection, a force can be exerted to push forwards and draw back the plunger.

SUMMARY OF THE INVENTION In accordance with one aspect the present invention provides a retractable safety syringe with a soft piston, comprising: 0a needle set, including a needle and a needle seat for holding said needle, 1said needle set having an engaging portion on a bottom thereof; O 10 a cylinder barrel having a needle set socket on an upper portion, and an N injection space at a lower portion, said needle set being connected to said needle set socket with a predetermined connecting force; a plunger provided at a lower end of the cylinder and adapted to move into space said plunger including a piston on a front portion thereof wherein a connecting piece is provided on a front end of the piston for engaging with said engaging portion, said piston being made of elastic material, and shaped to be compressed and restored; wherein said piston is adapted to be pushed by the plunger in to said injection space until a top surface of said piston contacts a top end wall in said injection space without engaging the engaging portion with the connecting piece so as to thereby dispense all medicine from the injection space; and wherein after removing the needle from a patient said piston is adapted to be further pushed under a force greater than the predetermined connecting force so as to compress and deform to allow the connecting piece to move away from the top surface of the piston and to engage with the engaging portion of the needle set thereby disconnecting the needle set from the needle set socket and allowing the needle set to be refracted into the cylinder barrel by movement of the plunger.

Preferably, the retractable safety syringe claimed in claim 1, wherein a scale mark identifying a quantity of injection liquid is provided at a top point of said injection space and is set to zero.

Preferably, the retractable safety syringe as claimed in claim 1, wherein said engaging portion of said needle set is provided on a base of said needle seat for connection with said connecting piece of said plunger.

5 Preferably, the retractable safety syringe as claimed in claim 1, wherein said needle set further includes an adapter, said needle seat being detachably connected with said adapter, said adapter being connected to said needle set socket of the cylinder barrel, and said engaging portion being formed on a base of said adapter.

Preferably, the retractable safety syringe as claimed in claim 3 or 4, wherein t said engaging portion is an engaging ratchet formed at a central portion of said base, and said connecting piece of said plunger is a rigid hook portion protruding 00 from the centre of the front end of said piston, wherein said hook portion is disposed at the front end of a piston shaft, wherein the piston shaft supports said piston.

IC Preferably, the retractable safety syringe as claimed in claim 5, wherein an extended protrusion is formed on the front end of said hook portion, whereby said hook portion is pierced into said engaging ratchet of said base of said needle set, said extended protrusion extends into a passage in the needle set for injection liquid.

The present invention will be apparent in its features and structure after reading the detailed description of the preferred embodiment thereof in reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a sectional view showing the structure of a conventional syringe; Fig. 2 is an analytic perspective view showing the elements of the embodiment of the present invention; Fig. 3 is a sectional view of the embodiment of the present invention; Fig. 4 is a sectional view showing drawing in the liquid for injection by the embodiment of the present invention; Fig. 5a is a sectional view showing a hook portion engages an engaging ratchet in the embodiment of the present invention; Fig. 5b is an enlarged sectional view showing the hook portion engages the engaging ratchet in the embodiment of the present invention; Fig. 6 is a sectional view of the embodiment of the present invention showing drawing back of a needle set; Fig. 7a is a coordinate plane showing the force in injecting medicine from N ml to 0 ml by the retractable safety syringe of the present invention; Fig. 7b is a coordinate plane showing the force in injecting medicine from N ml to 0 ml by the retractable safety syringe of the conventional syringe; Fig. 8 is a schematic sectional view showing another embodiment having an extended protrusion on the top end of the hook portion of the present invention; Fig. 9 is an enlarged sectional view showing the hook portion of Fig. 8 is engaged with an engaging ratchet of the present invention.

Fig. 10 is a partly sectional view showing a further example of the prevent invention applying to a needle set comprising a needle, needle seat and retractable adapter.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to Fig. 2 showing an embodiment of a manual retractable safety syringe of the present invention having a soft piston, the syringe is comprised of a needle set 40, a cylindrical barrel 50 and a plunger Wherein, the needle set 40 is comprised of a needle 41 and a needle seat 42 for fixing therein the needle 41; the needle seat 42 is in the form of a hollow pipe and is provided therein with an engaging ratchet 43. A hollow shaft of the needle 41 and the central portion of the needle seat 42 are both hollow and are communicated with the central portion of the engaging ratchet 43, such hollow portions form a passing space for medicine.

The cylindrical barrel 50 is a hollow cylinder, a space 52 for injection is provided on the rear part of the cylindricai barrel 50, and scale marks (taking ml as the unit) indicating the amounts of medicine are printed on the external surface of the cylindrical barrel 50. The cylindrical barrel 50 is formed on the front end thereof a needle set socket 51 to receive the needle seat 42 of needle set The plunger 60 is comprised of a piston 61 and a pusher rod 62; the piston 61 is made of elastic material. The pusher rod 62 is provided on the front end thereof with a piston shaft 621 (referring to Fig. the piston shaft 621 is provided on the top end thereof with a hook portion 622, the piston 61 is slipped over the piston shaft 621.

As shown in Figs. 2, 3, the piston 61 in this embodiment is made of elastic material, the piston shaft 621 on the front end of the pusher rod 62 has a length equal to the thickness of the piston 61; so that when the piston 61 is extended over the piston shaft 621, only the hook portion 622 of the piston shaft 621 protrudes out of the piston 61 to render the bottom end of the hook portion 622 to contact the piston 61. Referring to Figs. 3, 4, when the pusher rod 62 is pulled back to draw in medicine for injection, the front end face of the piston 61 is at the position where the top scale mark (indicating 0 ml) is, hence medicine can be drawn in with accurate amount.

When in injecting medicine, by virtue that the front end face of the piston 61 contacts with the bottom end of the hook portion 622, the plunger 60 can be stably pushed to a top point to completely eject all the medicine; and when in discarding a syringe, as shown in Figs. 5a and 5b, the piston 61 is pushed and compressed to deform, thereby the hook portion 622 of the piston shaft 621 is released from contact with the upper surface of the piston 61 to in turn push forwards the engaging ratchet 43 of the needle seat 42 and to engage with the engaging ratchet 43. And the needle set 40 can be pulled down into the cylindrical barrel And referring to Figs. 7a and 7b that respectively provide coordinate planes showing the force in injecting medicine by the retractable safety syringe of the present invention and of the conventional syringe, wherein the Y axis indicates the force that a medical worker exerts, while the X axis indicates the residual amount of medicine, the starting point represents that the amount of medicine in the cylindrical barrel is N ml, the amount is gradually reduced to 0 ml.

The retractable safety syringe of the present invention and the conventional retractable safety syringe are both poured in with N ml medicine. When in injection, before the residual amount of medicine is b ml, the retractable safety syringes of the present invention and the conventional one are exerted with forces of the same amount; and when injection is proceeded to having the residual amount of medicine of b ml, as for the conventional retractable safety syringe, the hook portion of the plunger thereof is pushed upwardly to contact the engaging ratchet on the bottom of the needle seat and is hindered from forwarding, the medical worker must put a force to eject the remaining medicine, increasing of force makes pain of a patient; while as for the present invention, force is stably exerted, no additional force is necessary to push the piston to the top point but injecting of medicine can be completed.

Referring to Figs. 8, 9, in the above stated embodiment of the present invention, an extended protrusion 623 can also be formed on the front end of the hook portion 622, so that when the hook portion 622 of the piston shaft 621 is pierced into the engaging ratchet 43 of the needle seat 42 to form an engagement state, the extended protrusion 623 formed on the front end of the hook portion 622 can be extended deeply into the needle seat 42 to occupy the space therein, thereby the residual amount of injection liquid can be further lowered.

In the drawings of the present invention, although the needle set socket 51 of the cylindrical barrel 50 is in the state of having a reduced diameter, if the needle set is of the structure of which the needle 41 is changeable, the needle set socket 51 of the cylindrical barrel 50 can also have its bottom enlarged to be in the form of a straight barrel to allow the needle set socket 51 and the cylindrical barrel 50 to have the same inner diameter, but the needle set 40 can be in the same way inserted for connection.

Fig. 10 is shown a further application of the present invention, wherein the needle set 70 is comprised of a needle 71, a needle seat 72, and a retractable adapter 73 having a retractable mechanism, such as an engaging ratchet 731.

And in the above stated drawings and specification, the engaging ratchet 43 on the base of the needle set 40 forms a connecting portion of a manual retractable mechanism, in which the shape of the arrangement the engaging ratchet 43 and the arrangement that the engaging ratchet 43 is located at the center of the base of the needle set 40 only form an embodiment of such a manual retractable safety syringe. In fact, the structure of the soft piston and the connecting piece of the plunger of the present invention can be applied to any manual retractable safety syringe having a connecting piece of the plunger and a connecting portion of the needle set of any of various shapes and at any of various locations. The structure of the soft piston and the connecting piece of the plunger of the present invention can also be applied to an automatic retractable safety syringe; in which the connecting piece of the plunger forms the activating piece to activate the retractable mechanism provided on the needle set.

In conclusion, the present invention surely provides an improved structure for the connecting piece or the activating piece for a piston and a retractable mechanism for use on a retractable syringe; the present invention thereby is industrially practical.

It will be apparent to those skilled in this art that various modifications or changes can be made to the elements of the present invention without departing from the spirit and scope of this invention; all such modifications and changes shall fall within the scope of the appended claims and are intended to form part of this invention.

9A In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country.

Claims

1. A retractable safety syringe with a soft piston, comprising: a needle set, including a needle and a needle seat for holding said needle, said needle set having an engaging portion on a bottom thereof; Sa cylinder barrel having a needle set socket on an upper portion and an injection space at a lower portion, said needle set being connected to said needle set 00 socket with a predetermined connecting force; ,I a plunger provided at a lower end of the cylinder barrel and adapted to move within the injection space, said plunger including a piston on a front portion NI thereof and a connecting piece provided on a front end of the piston for engaging with said engaging portion, said piston being made of elastic material, and shaped to be compressed and restored; wherein said piston is adapted to be pushed by the plunger into said injection space until a top surface of said piston contacts a top end wall in said injection space, without engaging the engaging portion with the connecting piece, so as to thereby dispense all medicine from the injection space; and wherein after removing the needle from a patient said piston is adapted to be further pushed so as to compress and deform to allow the connecting piece to move away from the top surface of the piston and to engage with the engaging portion of the needle set to thereby allow the needle set to be disconnected from the needle set socket when the plunger is moved by a force greater than the predetermined connecting force so to retract the needle set into the cylinder barrel.

2. The retractable safety syringe claimed in claim 1, wherein a scale mark identifying a quantity of injection liquid is provided at a top point of said injection space and is marked at zero.

3. The retractable safety syringe as claimed in claim 1, wherein said engaging portion of said needle set is provided on a base of said needle seat for connection with said connecting piece of said plunger. 11 S4. The retractable safety syringe as claimed in claim 1, wherein said needle Sset further includes an adapter, said needle seat being detachably connected with said adapter, said adapter being connected to said needle set socket of the cylinder O barrel, and said engaging portion being formed on a base of said adapter. The retractable safety syringe as claimed in claim 3 or 4, wherein said engaging portion is an engaging ratchet formed at a central portion of said base, and 00 said connecting piece of said plunger is a rigid hook portion protruding from the N, centre of the front end of said piston, wherein said hook portion is disposed at the front end of a piston shaft, wherein the piston shaft supports said piston.

6. The retractable safety syringe as claimed in claim 5, wherein an extended protrusion is formed on the front end of said hook portion, whereby said hook portion is pierced into said engaging ratchet of said base of said needle set, said extended protrusion extends into a passage in the needle set for injection liquid.

7. A retractable safety syringe substantially as herein described with reference to accompanying Figures 2 to 7a, and Figures 8 to Dated this 1 0 th day of June 2005 LIFE-SHIELD PRODUCTS, INC. By their Patent Attorneys GRIFFITH HACK Fellows Institute of Patent and Trade Mark Attorneys of Australia