WO2014072993A2

WO2014072993A2 - Folded- plunger auto-retractable disposable syringe

Info

Publication number: WO2014072993A2
Application number: PCT/IN2013/000655
Authority: WO
Inventors: Jai Hind RATHORE; Bharati RATHORE; Pratibha RATHORE; Neelam RATHORE; Bhuvan Chandra RATHORE
Original assignee: Rathore Jai Hind; Rathore Bharati; Rathore Pratibha; Rathore Neelam; Rathore Bhuvan Chandra
Priority date: 2012-11-08
Filing date: 2013-10-29
Publication date: 2014-05-15
Also published as: WO2014072993A3

Abstract

The present subject matter relates to a folded- plunger auto- retractable disposable syringe (100) which includes a needle carrier assembly (109) and a folded plunger assembly (111) for respectively inserting in an outermost barrel (106). The folded plunger assembly (111) is provided with at least one oppositely positioned circumferential C-groove (118) on the outer surface at its proximal end P constituting a ridge (130). The folded plunger assembly also includes at least one outwardly protruded finger lock (116) to get engaged with an outer plunger barrel (104), and a piston seal holder (112) structured at the proximal end P for holding a piston seal (114). The outer plunger barrel (104) includes at least two pair of oppositely positioned finger locks (128, 130 & 132, 134) wherein each pair of lock is diametrically aligned opposite to each other and positioned at the distal end of the barrel where two diameters of barrel bisect each other perpendicularly. The outer plunger barrel (104) is also provided with a second piston seal holder (120) at proximal end P for holdings second piston seal (122). The present subject matter also discusses about the needle carrier assembly (109) for housing in the outermost barrel 106 before inserting the folded plunger assembly (111). The needle carrier assembly (109) includes a hypodermic needle (107) provided with a needle seat (156) at its distal end to hold a needle (146) at the proximal end of the hypodermic needle (107). The needle carrier assembly (109) is further provided with a spring (148) surrounding the needle to (146) push the hypodermic needle (107) through the spring (148) and an axial (passage 164) present in a needle carrier hub (108). The needle carrier hub (108) is advantageously provided with three different diameters to firmly hold the needle seat (156). The present invention further explains that the outermost barrel (106) is designed to receive the folded plunger assembly (111) after getting in the needle carrier assembly (109), wherein the outermost barrel (106) is provided with a finger rest (136), two uniform obtuse-angled L-shaped inner circumferential conical groove (138 and 140) and a conical jacket opening (144) at the proximal end of the outermost barrel (106).

Description

TECHNICAL FIELD

The present invention relates to a safety syringe having an auto retractable needle for use in the medical or dental profession or in personal drug administration so that the physicians, surgeons or other needle operators may be protected from the needle-stick injury during its use. The invention, in particular, relates to an assembly of the safety syringe which is simple and easy in handling, in which the hypodermic needle retracts itself automatically by virtue of self generated vacuum and encapsulate within the barrel as soon as the last drop is injected in the body of patient. The syringe thereafter becomes finally locked to become non-reusable. The handling of syringe does not require any special training to the operators. It is simple in manufacture.

BACKGROUND

Generally, syringes are simple axial piston pumps with a plunger that fits tightly in a cylindrical barrel. The plunger can be pulled and pushed along inside the barrel, thereby creatin a pressure gradient. Additionally, many syringes carry a sharp and penetrating hollow needle that is intended to puncture the skin, mucous membrane and interna! organs of humans or animals for injection or removal of fluids, aerosols, or particulate suspensions.

Recently, there has been noticed growing evidences of needle-stick injuries for, not restricted to medical professionals, but also for the children playing in park, a street walkers and the like. Anyone affected by needle-stick injuries may be infected with serious blood born diseases. Further the danger of these injuries may escalate to possible infections from I-I.IV and hepatitis B, even to those medical practitioners who work with these used needles in their normal course of business.

There have been a number of proposals aimed at reducing these needle-stick injuries. Such proposals also include auto-retractable syringes. A number of patents and products have also been introduced in the markets relating to various auto-retractable syringes. In the retractable syringes, when the injection has been administered, the piston is pushed away from the leading end of the barrel by a spring or a similar biasing means and the needle lip is accordingly retracted into the barrel. However these syringes often suffer from the disadvantages i.e. splash occurs back when the needle is caused to be retracted, which makes the injection p ocess complicated and brings inconvenience for doctors and nurses. Conventionally, to activate the auto-retraction, the plunger of the syringe needs a hard push beyond the normal pressure. Therefore, if the needle of the syringe is drawn from the patient before the auto retraction is activated then it matters little how violent the initial kick-back is. On the other hand, if the auto retraction of the needle in the syringe is activated, whilst the needle is in the body of the patient, either accidentally or deliberately, it may be quite uncomfortable or cause undesirable damage to the tissues in which the needle is inserted . There is another kind of syringe in which the needle is retracted into the barrel under the action of spring after injection. However, in such kind of retractable syringes, the needle is retracted too fast which may result in bursting out of blood under the body pressure from the punctured hole on the body, which further brings secondary cross infections. The conventional syringes also lack in full-proof locking arrangement as well as effective retraction mechanism to prevent and restrict further use of syringes once used.

Thus, there is an urgent need for auto-retractable single use syringes which may overcome the above mentioned drawbacks and shortcomings t - provide a safe, reliable and user friendly auto-retractable syringes that can protect against accidental injuries too.

SUMMARY

An object of the present subject matter is to provide a folded plunger auto retractable syringe for single use.

Another object of the present subject matter is to provide a folded plunger auto- retractable syringe with a folded plunger assembly.

Another object of the present subject matter is (o provide a folded plunger assembly that includes an inner plunger barrel, an outer plunger barrel and a plunger plug.

Another object of the present subject matter is to provide a folded plunger assembly that includes an outer-most barrel to hold the folded plunger barrel.

Another object of the present subject matter is to provide an auto retractable syringe with a plunger plug to be inserted in an outermost barrel.

Another object of the present subject matter is to provide the plunger plug with a longitudinally furrowed knob. Another object of the present subject matter is to provide a needle carrier to . hold the needle.

Another object of the present subject matter is to provide an O-ring to support the needle carrier and to dislodge the needle carrier to actuate the retraction mechanism.

Another object of the present subject matter is to create a vacuum automatically when the plunger is pulled within the barrel.

Another object of the present subject matter is to uncover the needle of the syringe during the time of injecting or retracting the fluid.

Another object of the present subject matter is to lock the plunger barrel automatically inside the outermost barrel immediately alter the completion of injection process.

Another object of the present subject matter is to provide the inner plunger barrel with a pair of oppositely positioned finger locks on either end to get engaged with the outer plunger barrel.

Another object of the present subject matter is to provide the inner plunger barrel with a piston seal holder structured at the proximal end for holding a piston seal .

Accordingly, the subject matter described herein generally relates to a safely syringe having an auto-retractable needle for use in medical or dental profession or in personal ^' drug administration, so that the physicians, surgeons or other needle operators may be protected from needle-stick injuries after its use. Therefore, the invention, in particular, relates to an assembly of the safety syringe which facilitates simple operation and easy handling, in which the hypodermic needle automatically retracts itself by virtue of self generated vacuum during operation process and automatically encapsulates within the barrel, as soon as the last drop of medicine is injected in the body of patient. The syringe, thereafter, automatically locks itself (o become non-reusable. It describes a simple technique which is easy in manufacture and does not require any special training to the operators^' for handling.

BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS

These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompaiiying drawings in which the like characters represent the like parts throughout the drawings, wherein:

Fig 1 (a) illustrates a line diagram of an inner plunger barrel of a folded-plunger auto- retractable disposable syringe.

Fig 1(b) illustrates a line diagram of an outer plunger barrel of the folded-plunger auto- retractable disposable syringe.

Fig 1(c) illustrates a line diagram of two pai of fmger locks in the outer plunger barrel of the folded-plunger auto-retractable disposable syringe.

Fig 1(d) illustrates a line diagram of a plunger assembly of the folded-plunger auto- retractable disposable syringe.

Fig 2 illustrates a line diagram of an outermost barrel of the folded-plunger auto- retractable disposable syringe.

Fig 3 illustrates a line diagram of a needle carrier assembly of the folded-plunger auto- retractable disposable syringe.

Fig 3(a) illustrates a line diagram of the needle carrier hub provided with a spring mechanism.

Fig 3(b) illustrates a line diagram of the needle carrier hub provided with a springless mechanism.

Fig 3(c) illustrates a line diagram of the springless needle carrier hub along with hypodermic needle, wherein the parallel circular ring plates 150 and 152 are respectively substituted with the two gasket rings (182 and 184).

Fig 4 illustrates a line diagram of the needle carrier hub housed inside the conical jacket of the o ler most. barrel of folded-plunger aulo-rclractable disposable syringe.

Fig 5 illustrates the complete assembly of folded-plunger auto-retractable disposable syringe.

Fig 6 illustrates a united assembly of the two plunger barrels in the folded-plunger auto- retractable disposable syringe. Figs 7 to 12 illustrate the complete process of injecting the medicine into the body of the patient by the folded-plunger auto-retractable disposable syringe.

DETAILED DESCRIPTION

The embodiments of the present subject matter are described in detail with reference to the accompanying drawings. However, the present subject matter is not limited to these embodiments which are only provided to explain more clearly the present subject matter to the person ordinarily skilled in the art of the present disclosure. In the accompanying drawings, like reference numerals are used to indicate the like components.

The invention is explained with respect to a safety syringe incorporating an auto retractable needle assembly therein. Generally, the safety syringe includes a syringe barrel and a plunger slidably located therein. The plunger is designed with a proximal and a distal end with piston means associated therewith at its distal end so as to be seal ingly slidable within the barrel.

The folded-plunger auto-retractable disposable syringe (FAD) 100, according to a preferred embodimen of the present subject matter, is structurally constructed with an inner plunger barrel 102, an outer plunger barrel 104, an outer mos barrel 106 and a needle carrier assembly 1 9.

The inner plunger barrel 102, as shown in Fig. l (a), comprises of a uniformly hollow cylindrical tubular body, provided with a thumb rest 110 at its distal end D and a centrally positioned piston seal holder 112 at proximal end P for holding a first piston seal 114, in an embodiment of the present subject matter. The inner plunger barrel 102 is designed with at leas one outwardly protruded finger lock 116, opening at the distal end D. The finger lock 116 is designed and shaped by cutting the wall of plunger barrel 102. The proximal end E of (he inner plunger barrel 102 is provided with two uniform face to face positioned circumferential C- grooves 118 at the outer surface, constituting a ridge 119 at its proximal end P .

The outer plunger barrel 104, as shown in Fig.l (b) includes a uniformly elongated hollow cylindrical tubular body provided with a centrally positioned piston seal holder 120 at its proximal end, holding second piston seal 122. The piston seal holder 120 is designed with a furrowed axial nipple 124, which is further provided with a locking element 126 at its proximal end. The outer plunger barrel 104 is designed with at least two pairs of finger locks (128, 130 & 132, 134), wherein each pair of lock is diametrically aligned opposite to each other and positioned at the distal end of the barrel where two diameters of barrel bisect each other perpendicularly, as shown in Fig.l (c). In first pair of finger lock (132 and 134), each lock protrudes in outward direction and opens towards the distal end of the outer plunger barrel 104. In second pair of finger lock (128 and 130). each lock protrudes inwardly and opens at the distal end. The distal end of each finger lock (128 and 130) is modified into inwardly protruded teeth T- J and T-2. The thickness of the teeth T- l and T-2 is almost double to that of the wall of barrel 104. The proximal surface of teeth is designed perpendicular to the inner surface of barrel 104, whereas the distal surface is inclined to the proximal end, finally constituting a conical oblique notch. The locks are designed and shaped by cutting the wall of the outer plunger barrel 104.

The outer most barrel 106, as shown in Fig. 2, includes a uniformly elongated hollow cylindrical tubular body, provided with a finger rest 136, two uniform obtuse angled L-shaped inner circumferential conical grooves (138 and 140). The first groove 138 is positioned at the distal end D of the outer most barrel 106 and the second groove 140 is positioned in the middle of the barrel 106. Each of the conical grooves is obliquely and slidably inclined towards the proximal end of the outer most barrel 106, whereas the distal end of each conical groove is perpendicular to the inner surface of the outermost ban-el 106. The outer most barrel 106 is customized into a conical jackef 144, opening at the proximal end of the barrel, which is further provided with a third inner circumferential conical groove 142 at the proximal end of the outer most barrel 106 in an embodiment of the present subject matter.

In an embodiment of the present subject matter, the outer diameter of the outer plunger barrel 104 is uniformly equal to the inner diameter of the outermost barrel 106 and is also uniformly equal to the outer diameter of the distal portion D of the inner plunger barrel 102. Further, the inner diameter of the outer plunger barrel 104 is uniformly equal to the outer diameter of the proximal portion E of the inner plunger barrel 102. ^'The outer diameter of the remaining middle portion between D and E of the inner plunger barrel 102 is iinilbrinly equal to the distance between inwardly protruded oppositely positioned teeth T- l and T-2 of the finger locks 128 and 130. In an embodiment of the present subject matter, the outer diameter of distal portion D of the inner plunger barrel 102 is uniformly equal to the outer diameter of the outer plunger barrel 104 and further equal to the inner diameter of the outermost barrel 108. Fig. 3 illustrates the needle carrier assembly 109, which includes a straight, hollow and pointedly sharp hypodermic needle 1 7, a spring 148, elastic O-ring 174 and a needle carrier hub 108.

The hypodermic needle 107 comprises of a seat 156 at its distal end holding a sharp and pointed hollow needle 146. The axial passage of the hypodermic needle 146 is uniformly equal throughout the length of the needle, which opens in a cavity 158 at its distal end. A locking means has also been provided to replace the needle 146 (not shown). The needle 146 is enclosed within the needle cover 190.

The inner diameter of cavity 158 is equal to the outer diameter of furrowed nipple 124. The cavity 158 is provided with a locking member 160 inside the proximal end to snap lock the locking member 126 of nipple 124. At the distal end, the needle seat 156 is modified into a collar 162 which has an outer diameter equal to the inner diameter of axial passage 164 of the needle carrier hub 108 at its distal end. The diameter of the remaining portion of the needle seat 156 is equal ^'to the inner diameter of middle portion of axial passage 164 of the needle hub 108. In an embodiment of the present subject matter, the outer diameter of remaining proximal portion of needle seat 156 is equal to the inner diameter of axial passage 164 at its proximal portion, opening outside at proximal end. A conical outer circumferential groove 166 has also been provided in the middle at the distal portion of seat 156 to snap lock the hypodermic needle 107 inside t he needle carrier hub 108 with the help of tooth T-3 of finger lock 168.

The needle carrier hub 108, as shown in Fig 3 (ii), is a hollow conical body having axial passage 164, parallel to the outermost barrel 106, which is provided with three different inner diameters to fixedly hold the needle seat 156. The inner diameter of axial passage 1.64 of needle carrier hub 108 at distal end is equal to the outer diameter of collar 162 of the hypodermic needle 107. In another embodiment of the present subject matter, the inner diameter of proximal portion of the axial passage 164 is equal to (he outer diameter of proximal portion of needle seat 156. Further, the inner diameter of middle portion of axial passage 164 is equal to the outer diameter of the distal portion of needle seat 156, which constitutes a radial passage around the distal portion of needle seat 156, between the distal portion of needle hub 108 and the distal portion of the needle seat 156, to hold the compressed spring 1 8. The middle portion of the needle hub 108 is provided with atleast one finger lock 168 which is provided with an inner tooth T-3 having proximal surface perpendicular to the inner surface of the wall of needle hub 108. The distal surface of tooth T-3 is obliquely inclined to the distal end, thus finally constituting a conical notch to snap hold the needle seat 156 inside the needle hub 108. The conical notch snap holds the needle seat 156 inside the needle hub 108 by seating fixedly in the outer circumferential conical groove 166 of the needle seat 156.

The distal end of the finger lock 168 is customized and extended outwardly to constitute an elongated flange 170 which is obliquely inclined in outward direction, directing to the distal end of the needle carrier hub 108. The end tip of the flange 170 finally becomes flattened and perpendicular to the inner walls of outer most barrel 106. The proximal end of (he needle carrier hub 108 is provided with an outer circumferential conical lock- ridge 172 to snap lock the needle carrier hub 108 inside the comical jacket 144 of the outer most barrel 106 by conveniently seating within the inner circumferential conical groove 142, provided in the outermost barrel 106 at its proximal end.

The distal end of the needle carrier hub 1 8 is customized into a collar 176, which is perpendicular to the inner surface of the outermost barrel 106. The outer diameter of collar 176 is equal to the inner diameter of the O-ring 174. The distal portion of needle carrier hub 108 is fixedly surrounded by an elastic O-ring 174, whose outer diameter is equal to the inner diameter of outermost barrel 106.

The present invention explains that on inserting the hypodermic needle 107 along with the spring 148 into the needle carrier hub 108 through its distal end, the needle 146 passing through its axial passage 164, protrudes out through its proximal opening end. On further pressing the hypodermic needle 107 in forward direction, the spring 1 48 is compressed and the tooth T-3 of linger lock 168 occupies the outer circumferential groove 166 of needle seat 156 with a click to snap lock (he hypodermic needle 107 into the needle carrier hub 108 as shown in Fi 3(ii).

The needle carrier hub 108 along with hypodermic needle 107 and the O-riug 174 is inserted into the outermost barrel 106 through its distal end, which is finally housed inside the conical jacket 144 of the outermost barrel 106. During this process, the outwardly protruded conical ridge 172 at the outer diameter of needle carrier hub 108 conveniently seats into the inner circumferential conical groove 142 of conical jacket 144 to snap lock the needle carrier hub, in an embodiment of the present subject matter. The elastic O-ring 174 is fitted between the needle carrier hub 154 and the inner surface of outermost barrel 106 in such a manner, that the proximal ends of the O-ring 174 rest in contact with the distal surface of the flattened tip of flange 170 of the finger lock 168, as shown in Fig.4.

When the O-ring 174 is pushed by plunger in forward direction during completion of injection, the O-ring pushes the end-tip of flange 170 in forward direction to open the finger lock 168 which results in the release of hypodermic needle 107, consequently, the needle gently dislodges and moves smoothly in backward direction due to expansion of compressed spring 148. Thus, the basic function of needle carrier hub 108 is to provide a mechanism to securely catch hold the hypodermic needle inside its axial passage and to release the needle by opening the finger lock 168, provided in the needle carrier hub 108, on completion of injection. The needle carrier hub along with hypodermic needle may be shaped and designed in various ways without departing the real spirit of this mechanism of this invention.

In an embodiment of the present subject matter, the needle carrier may be designed and shaped in a manner that the spring 148 is housed in the proximal portion of needle carrier hub, in particular between the proximal portion of (he needle seat and the inner surface of needle carrier hub, as shown in FIG 3(a).. This embodiment of present subject matter facilitates a combination of two circular ring- plates (150 and 152) to press the arched flange 180 of linger lock 168. The distal plate 150 is diametrically provided with two holes (n and b) in combination of two parallel ring plates 150 and 152. The outer diameter of the distal plate 150 is equal to inner diameter of outermost barrel 106, whereas the inner diameter is ecjual to the outer diameter of distal portion of the needle carrier hub 108. The distal plate securely holds the needle carrier hub 8 inside the conical jacket 1.44 of the outermost barrel 106. The proximal ring plate 152 has its inner as well as outer diameters slightly lesser than the distal plate 150, so that it is loosely held paraliely between the needle carrier hub .108 and the inner surface of conical jacket 144. The proximal plate 150 is also provided with two parallel pins P-l and P-2 diametric to the plates. The pins P- 1 and P-2, extend outside the distal end of the distal plate 150 and slidab!y pass through the holes (a and b) of the distal plate 150. When the pins (P-l and P-2) arc pressed by plunger in forward direction during the completion of injection, the loosely held proximal plate 152, resting on the distal surface of arched flange 180, pushes the flange 180 in forward direction. Consequently, the finger lock 168 opens and sets free the hypodermic needle 107, which gently moves in backward direction due to the expansion of spring 1 8.

Fig. 3(b) shows an embodimen of the present subject matter, wherein the needle carrier hub along with the hypodermic needle is provided with a springless mechanism with description as described in earlier embodiment and illustrated in Fig 3 (a).

Fig. 3(c) shows a further embodiment of the springless needle carrier hub along with hypodermic needle, wherein the parallel circular ring plates 150 and 152 are substituted with two gasket rings 182 and 184 respectively.

fn an embodiment of the present subject matter, the inner diameter of circular gasket ring 182 is equal to the outer diameter of distal portion of needle carrier hub, whereas the outer diamete of gasket ring 182 is equal to the inner diameter of elastic gasket O-ring 184. Additionally, the width of gasket O-ring 184 is kept sufficiently large, so that it may extend outside the needle carrier hub at the distal end as shown in Fig 3 (c). These two gasket rings, in combination, hold the needle carrier hub inside the conical jacket 144 of the outermost barrel 106. The gasket O-ring 184 is slidably fixed between the gasket ring 182 and the inner surface of the outermost barrel 106. The proximal end of the gasket ring rests at the distal surface of flange of the finger lock 168.

When the outwardly extended distal end of the gasket O-ring 184 is pressed by the plunger in forward direction during the completion of the injection, the proximal end of gasket O-ring pushes the flange of finger lock 168 in forward direction to open the linger lock 168 which facilitates the release of hypodermic needle 107 in backward direction.

During assembly of syringe 100, in a preferred embodiment of the subject matter, the proximal end E of the inner plunger bane) 102 is inserted into the outer plunger barrel 104 through its distal end. The inner plunger barrel 102 is inserted in such a manner that the inwardly protruded teeth T-1 and T-2 of the finger locks 128 and 130 become in alignnienl of the flat portion provided between two oppositely positioned facc-to-facc circumferential conical C- groove 118 at the outer surface of inner plunger barrel 102, This results in the expansion of teeth T-1 & T-2 of the finger lock 128 and 130 in outward direction as the outer diameter of the proximal portion E of the inner plunger barrel 102 is equal to the innerdiameler of outer plunger barrel 104. After crossing proximal portion E and sliding over the ridge 119, the teeth 128 and 130 restore their norma] state and come in contact of the outer surface of the middle portion of inner plunger barrel 102, because the outer diameter of middle portion of the inner plunger barrel 102 is equal to the distance between the teeth 128 and 130. Since, the outer diameter of distal portion D of the inner plunger barrel 102 is equal to the outer diameter of outer plunger barrel 104, the distal portion of outer plunger barrel 104 rests in contact with the proximal end of the distal portion D of inner plunger barrel 102 to constitute a plunger assembly 11 1 as shown in Fig 1 (d). At this stage, the inner plunger barrel 102 is rotated to 60 to 90 degree angle in either direction with the help of thumb rest 110 of the inner plunger barrel, so that the flat portion lying between the-outer circumferential C-grooves 118 is misaligned from the pair of tooth T-l and T- 2 of finger locks 128 and 130.

The plunger assembly 111 is inserted into the outer most barrel 106 through its distal end with the help of the thumb rest 110 and the fmger rest 136, On complete insertion of the plunger assembly inside the outermost barrel 106, the outwardly protruded pair of finger locks (132 and 134) slip inside the inner circumferential groove 138 of the outer plunger barrel with a click and restore normal state to prevent the plunger assembly to be pulled out again from the outermost barrel 106, This constitutes the complete assembly of safely syringe 100, as shown in Fig 5.

While working with the syringe 100, the user has to pull out the inner plunger barrel 102 from the outermost barrel 104, by holding the syringe 100 with the help of the thumb rest 1 10 and the f ger rest 136. When the inner plunger barrel 102 is pulled out at its ull length, a vacuum V is created between the inner plunger barrel 102 and the outer plunger barrel 104. The inwardly protruded finger Jocks 128 and 130 extend in outward direction while passing over the circumferential ridge 1 19 provided at the distal end of the proximal portion E of the inner plunger barrel 102. The inner- circumferential conical groove 138 facilitates the required space for the finger locks 128 and 130 to conveniently extend in the outward direction while passing over the circumferential ridge 1 19. Consequently, the two plunger barrels 102 and 104 unite together to behave like a single plunger barrel as shown in Fig 6.

At this stage it is important to note that the united plunger barrel formed by the union of the inner and the outer plunger barrels 102 and 104 respectively, cannot be pulled out further in baclcwaj d direction, because the diametrically aligned outwardly protruded finger locks 132 and 134 become securely engaged and occupy the inner circumferential groove 138 provided at the distal end of the outermost barrel 106. This engagement does not allow the outer plunger barrel 104 to move further in backward direction. The united plunger barrel may only be pushed in forward direction to the full length and then be pulled alternatively in backward direction to suck the medicinal dosage to be injected into the body of patient. Fig.6 shows how the needle cover 190 is removed to uncover the needle 146. The needle may also be replaced as per the requirement with the help of lock provided therein (not shown).

Figs 7 to 9 illustrate other embodiments of the present subject matter which shows how the medicinal dose may be injected into the body of the patient. While injecting the medicinal dose into the body of patient, the movement of united plunger assembly in forward direction simultaneously initiates and executes the following actions at the final stage of completion of injection;

Firstly, the furrowed nipple 124 inserts into the cavity 158 through its distal end and gets snap locked therein with the help of locking members 126 and 160.

Secondly, the proximal end of the united plunger assembly pushes the O-ring 178 in forward direction, which in turn pushes simultaneously the end- tip of flange 170 of the finger lock 168 in forward direction. It results in the opening of finger lock 168 to unlock hypodermic needle 107 from the needle carrier hub 108.

Thirdly, the compressed spring 148, housed within the cavity between needle seat 156 and the needle carrier hub 108, expands due to the unlock of lock 168 and pushes the hypodermic needle 107 in backward direction to dislodge the hypodermic needle 107 from the needle carrier hub 108.

Fourthly, the inwardly protruded finger locks 128 and 130 reach in alignment of the inner circumferential conical groove 140 at this stage. The continuously mounting pressure on the thumb rest 1 10 keeps on pressing the united plunger assembly in forward direction, but at the completion of injection no space is left between the proximal end of the united plunger ass-embly and the needle carrier hub 108. Since, the united plunger assembly has no space to move in forward direction, so the entire pressure being exerted on the thumb rest 110, concentrates on the join of united plunger assembly. Consequently, the finger locks 128 and 130 expand in outward direction due to this exerted pressure. Further, the inner circumferential conical groove 140 facilitates the expansion of finger locks 128 and 130 in outward direction. As soon as the finger locks 128 and 130 expand in outside direction, the teeth (T-l and T-2) dislodge from the outer conical circumferential groove 118 and slide over the outer circumferential ridge 119 due to the movement of inner plunger barrel 102 in forward direction. The teeth (T-l and T-2) now restore their normal state and come in contact of oute surface of middle portion of the inner plunger barrel, thus facilitate sliding of the outer plunger barrel 104 in backward direction due to the pull of vacuum between two plunger barrels 102 and 104.

In this way, the outer plunger barrel 104, holding the hypodermic needle at its proximal end gently moves smoothly in backward direction due to the push of spring 148 and the vacuum V existing between the two plunger barrels 102 and 104 to retract the hypodermic needle inside the outer plunger barrel 106, as shown in Fig 10.

And finally, the distal portion D of inner plunger barrel 102 smoothly slips into the outermost barrel 106 along with outwardly protruded lock 116, which click locks the inner plunger barrel 104 within the outermost barrel by expanding finger locks 132 and 134 in outward direction and occupying the space provided by inner circumferential groove 138, provided at the distal end of outer plunger barrel 106, as illustrated in Fig. 11.

Thus, on completion of injection, the hypodermic needle is automatically retracted smoothly in backward direction and encapsulates within the outermost barrel 106, in consequence of which, the syringe automatically becomes locked and useless for any further use, as illustrated in Fig. 12.

The folded plunger auto-retractable syringe 100 according to present subject matter facilitates an automatic control on the movement of plunger inside the barrel, thus providing the apt pressure and method of injecting as well as retracting the fluid through the syringes. Further, the syringe 100 retractable syringes as per the present subject matter have to be disposed off safely in a container as there is no option to re-use the same syringe. In other words, the present invention facilitates the ίη-operation of same syringe by virtue of the retention of collapsed needle within the barrel. Hence, possible infections from HIV, hepatitis B, and the like to people can be reduced to a great extent. Additionally, the safely syringe according to the present subject matter is user-friendly and cheap also that encourage its usage too.

Although the invention has been described with reference to specific embodiments, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as alternate embodiments of the invention, will become apparent to persons skilled in the art upon reference to the description of the invention. It is therefore contemplated that such modifications, can be made without departing from the spirit or scope of the present invention as defined.

Claims

&We Claim:

1. A folded- plunger auto-retractable disposable syringe 100 comprising:

a folded plunger assembly 111 for slidably inserting in an outermost barrel 106, the folded plunger assembly 111 comprising:

an inner plunger barrel 102 provided with at least one oppositely positioned circumferential C-groove 118 on the outer surface at its proximal end P constituting a ridge 130, at least one outwardly protruded finger lock 1 16 to get engaged with an outer plunger barrel 104, a piston sea! holder 1 2 structured at the proximal end P for holding a piston seal 114;

the outer plunger barrel 104 comprising at least two pair of oppositely positioned finger locks (128, 130 & 132, 134) wherein each pair of lock is diametrically aligned opposite to each other and positioned at the distal end of the barrel where two diameters of barrel bisect each other perpendicularly, and a second piston seal holder 120 at proximal end V for holding second piston seal 122;

a needle carrier 'assembly 109 for housing in the outermost barrel 106 before inserting the folded plunger assembly 111 , the needle carrier assembly 109 comprising:

a hypodermic needle 107 provided with a needle seat 156 at its distal end to hold a needle 146 at the proximal end of the hypodermic needle 107;

a spring 148 surrounding the needle to 146 push the hypodermic needle 107 through the spring 148 and an axial passage 164 present in a needle carrier hub 108;

the needle carrier hub 108 is provided with three different diameters to firmly hold the needle seat 156;

elastic O-rings 174 to support and hold the needle carrier assembly 109 inside the outermost barrel 106, and to dislodge the assembly on completion of injection; the outermost barrel 106 designed to receive the folded plunger assembly 111 after getting in the needle carrier assembly 109, wherein the outermost barrel 106 is provided with a finger rest 136, two uniform obtuse-angled L-shaped inner circumferential conical groove (138 and 140) and a conical jacket opening 144 at the proximal end of the outermost barrel 106.

2. The folded- plunger auto-retractable disposable syringe 100 as claimed in claim 1 , wherein the piston seal holder 120 is designed with a furrowed axial nipple 124 and a locking element 126 at its proximal end.

3. The folded- plunger auto-retractable disposable syringe 100 as claimed in claim 1 , wherein the distal end of each finger lock (128 and 130) is modified into inwardly protruded teeth T-l and T-2 whose thickness is double to that of the wall of barrel 104.

4. The folded- plunger auto-retractable disposable syringe 100 as claimed in claim 1 , wherein the finger locks are designed and shaped by cutting the wall of the outer plunger barrel 104.

5. The folded- plunger auto-retractable disposable syringe 100 as claimed in claim 1 , wherein the outer diameter of the outer plunger barrel 104 is uniformly equal to the inner diameter of the outermost, barrel 106 and is also uniformly equal to the outer diameter of the distal portion D of the inner plunger barrel 102.

6. The folded- plunger auto-retractable disposable syringe 100 as claimed in claim ! , wherein the piston seal holder 120, designed with a furrowed axial nipple 124, is further provided with a locking element 126 at its proximal end.

7. The folded- plunger auto-retractable disposable syringe 100 as claimed in claim 1 , wherein the inner diameter of the outer plunger barrel 104 is uniformly equal to the outer diameter of the proximal portion B of the inner plunger barrel 1 2.

8. The folded- plunger auto-retractable disposable syringe 100 as claimed in claim 1 , wherein the outer diameter of the remaining middle portion between D and E of the inner plunger barrel 102 is uniformly equal to the distance between inwardly protruded oppositely positioned teeth T of the finger locks 128 and 1 0.

9. The folded- plunger auto-retractable disposable syringe 100 as claimed in claim I, wherein the outer diameter of distal portion D of the inner plunger barrel 102 is uniformly equal to the outer diameter of the outer plunger barrel 104 and further equal to the inner diameter of the outermost barrel 108.

1 . The folded- plunger auto-retractable disposable syringe 100 as claimed in claim 1 , wherein the needle 146 is enclosed within the needle cover 1 0.

11. The folded- plunger auto-retractable disposable syringe 100 as claimed in claim 1 , wherein the inner diameter of axial passage 164 of needje carrier hub 108 at distal end is equaJ to the outer diameter of collar 162 of the hypodermic needle 107.

12. The folded- plunger auto-retractable disposable syringe 100 as claimed in claim 1 , wherein the inner diameter of proximal portion of the axial passage 164 is equal to the outer diameter of proximal portion of needle seat 156.

13. The folded- plunger auto-retractable disposable syringe 100 as claimed in claim J , wherein the inner diameter of middle portion of the axial passage 164 is equal to the outer diameter of the distal portion of the needle seat 156, which constitutes a radial passage around the distal portion of the needle seat 156, between the distal portion of the needle hub 108 and the distal portion of the needle seal 156, to hold the compressed spring 148.

14. The folded- plunger auto-retractable disposable syringe 100 as claimed in claim 1 , wherein the middle portion of the needle hub 154 is provided with atleast one finger lock 1 8 which is provided with an inner tooth T-3 having proximal surface perpendicular to the inner surface of the wall of needle hub 108.

15. The folded- plunger auto-retractable disposable syringe 100 as . claimed in claim 1 , wherein the proximal end of the outer diameter of needle carrier hub 108 is provided with the circumferential conical lock- ridge 172 to snap lock the needle carrier hub 1 8 inside the conical jacket 144 of the outer most barrel 106 by conveniently seating within the inner circumferential conical groove 142 provided in the outermost barrel 106 at its proximal end .

16. The folded- plunger auto-rclractable disposable syringe 100 as claimed in claim 1 , wherein the needle carrier hub 108 provides a mechanism to securely catch hold the hypodermic needle inside its axial passage and to release the needle by opening the finge lock 168, provided in the needle carrier hub 108, on completion of injection.

17. The iblded- plunger auto-retractable disposable syringe 100 as claimed in claim 1 , wherein the needle carrier assembly is provided with a combination of two circular ring- plates (150 and 152) to press the arched flange 180 of finger lock 168.

18. The folded- plunger auto-retractable disposable syringe 100 as claimed in claim 1 , wherein the distal plate 150 is diametrically provided with two holes (a and b) in combination of two parallel ring plates 150 and 152.

19. The folded- plunger auto-retractable disposable syringe 100 as claimed in claim 1 , wherein the proximal plate 150 is provided with two parallel pins P-l and P-2 which slidably passes through the holes (a and b) of the distal plate 150 when the pins (P- l and P-2) are pressed by the plunger in forward direction.

20. The folded- plunger auto-retractable disposable syringe 100 as claimed in claim 1 , wherein the needle carrier hub along with the hypodermic needle is provided with a spring less mechanism.

21. The folded- plunger auto-retractable disposable syringe 100 as claimed in claim J , wherein the parallel circular ring plates 150 and 152 are respectively substituted with the two gasket rings (182 and 184).

22. The folded- plunger auto-retractable disposable syringe 100 as claimed in claim 1 , wherein on complete insertion of the plunger assembly 111 inside the outermost barrel 106, the outwardly protruded pair of finger locks (132 and 134) occupy the inner circumferential groove 138 of the outer plunger barrel with a click, which prevents the plunger assembly to be pulled ou again from the outermost barrel 106,

23. The iblded- plunger auto-retractable disposable syringe 100 as claimed in claim 1 , wherein a vacuum V is created between the inner plunger barrel 102 and the outer plunger barrel 104 when the inner plunger barrel 102 is pulled out at its full length.