A SAFETY SYRINGE

Abstract: The present invention relates to syringes (2) which are disabled after use by the retraction of the needle. The invention provides a bias by means of a negative pressure or a spring (72) produced by the movement of the plunger (8) away from one-way valves (36). The negative pressure produced in cooperation with the collapse of the syringe body (10) will force the plunger (8) to go through its full travel, involuntarily of the operator's actions. When the travel of the plunger is completed, cutting means (64, 66) detach the needle (60) from the syringe body (10), and captures the needle (60) inside the body (10) of the syringe (2) where it makes the used syringe safe. The invention provides the advantage over prior art syringes which require a voluntary act on the part of the operator to disable them, by making the disablement of the syringe (2) an involuntary action.

Description: A SAFETY SYRINGE FIELD OF THE INVENTION The present invention relates to single fill and use syringes. BACKGROUND ART Prior art single fill and use syringes are copious in number, but to date none have been able to entirely disable the syringe in an involuntary manner. Generally some manual disablement activity, other than the normal operation of the syringe, is required. SUMMARY OF THE INVENTION The present invention provides a syringe including a plunger adapted to slide in a body, said syringe being characterised by said body being collapsible behind said plunger when said plunger is pushed into said body, towards a needle end of said body. Preferably said body has at least one longitudinal line of weakness. Preferably said plunger includes at least one scoring blade and/or a paring blade, which allows said body to collapse along said line of weakness by a negative pressure produced by said plunger as said plunger moves towards the needle end. Preferably said blades only engage the lines of weakness at predefined intervals defined by calibrations on the internal surface of said body. The present invention also provides a syringe of the retractable needle type said syringe including a plunger whereby said needle is retracted by a bias produced when said plunger is moved in a direction towards said needle. Preferably said plunger includes a detachable plug means to engage said needle and seal same. Preferably said needle and said seal retract into a cavity in said plunger. Preferably said bias is formed by a negative pressure produced behind said plunger as said plunger moves towards said needle. It is alternatively preferred that said bias can also be created by a spring means, or from a combination of said spring means and a negative pressure. Preferably said needle is retracted to a position and held in said position in a positive manner. Preferably said plunger including cutting means to separate said needle from the body. Preferably said cutting means is circumferential and when not in use is in expanded form. Preferably as said cutting means nears a seal holding said needle in said body, said cutting means is directed to cut said seal by direction means. Preferably said direction means are circumferentially located around said needle. Preferably said direction means also includes an inclined plane to make said cutting means engage and cut said seal. Preferably said needle has a plug release means to release a plug on said plunger, said needle including a securing means to secure said plug into said needle. Preferably said securing means is a circumferentially or radially configured barbs. Preferably said plunger has a stem which passes through the boy of said syringe, said stem being slidably sealed relative to said body. Preferably said stem is of a tapered construction to enable an increased sealing force to be applied as the stem moves through the syringe body. Preferably said stem of the plunger has a disengageable securing means, to selectively allow operation of the syringe. The present invention further provides a syringe of a single use type, said syringe comprising a collapsible body and a plunger, said body including at least one one-way valve that will allow air to escape from said body when said plunger is drawn back, said valve preventing ingress of air when said plunger is moved towards said needle. Preferably said plunger includes a cavity defined by a flexible conduit, said conduit being characterised by a substantially smooth surface when in the extended position. The present invention, also further provides a safety needle comprising a passage there through and an articulated tip having an upper and a lower sealing ring, said tip including a capillary extending beyond said lower and said upper sealing ring, such that any non- longitudinal force exerted on said tip will rotate said tip, thereby closing the passage in said needle. Body also including a series of deformations on the internal and external surfaces of said body. Preferably deformations have a rounded profile and are circumferential in nature. Preferably inner and outer deformation are offset. Preferably the radius of the deformations is of the order .05mm to .75mm. Preferably said valve element is a ball attached to a leaf spring to bias said valve element to shut off said valve. The invention further provides a method of disabling a syringe, said syringe including a body, plunger and needle, said method including the steps of: forming a bias by the movement of the plunger in the direction of a needle end of said syringe; and retracting said needle into said body, by said bias, when said plunger reaches said needle end. Preferably said bias results in the collapse of the body behind the plunger to force said plunger in the direction of said needle end. Preferably said bias includes a negative pressure. Preferably the negative pressure is produced in association with at least one one way valve located in said body. Preferably said method includes the step of plugging said needle. Preferably said method includes a step separating said needle from said body, by said plunger moving to the limit of its travel. BRIEF DESCRIPTION OF THE DRAWINGS An embodiment of the present invention will now be described with reference to the accompanying drawings in which: Figure 1 is a schematic view of a syringe embodying the present invention, in a ready to use position; Figure 2 is a cross section through line III - HI of figure 1 ; Figure 3 illustrates in detail, a portion of figure 2; Figure 4 is a cross section into the page area IV of figure 1 ; Figure 5 illustrates in detail, area V of figure 1 ; Figure 6 illustrates in detail, a portion of figure 5; Figure 7 illustrates in detail, area IX of figure 1 ; Figure 8 illustrates in detail, a portion of figure 7; Figure 9 illustrates a schematic view of the apparatus of figure 1 in use; Figure 10 illustrates a part of figure 9 in detail; Figure 11 illustrates in detail, area VI of figure 1; Figure 12 illustrates an alternative to apparatus of figure 11 ; Figure 13 illustrates in detail, area VII of figure 1; Figure 14 illustrates a cross section through the apparatus of figure 13; Figure 15 illustrates the apparatus of figure 13 when it is extended; Figure 16 illustrates a cross section through the apparatus of figure 15; Figure 17 illustrates a side view of the apparatus of figure 15; Figure 18 illustrates in detail, of part of the apparatus of figure 7; Figure 19 illustrates in cross section, area XI of figure 1; Figure 20 illustrates the apparatus of figure 19 when out of alignment; Figure 21 illustrates in cross section, a syringe which incorporates a second embodiment of the present invention ; Figure 22 illustrates the syringe of figure 21 in half withdrawn mode; Figure 23 illustrates the plunger the apparatus of figure 21 in cross section; Figure 24 illustrates an underneath view of the apparatus of figure 23; Figure 25 illustrates a detail of the interaction of the plunger and the needle mounting in the apparatus of figure 21 ; Figure 26 illustrates a detail of the valves of the apparatus of figure 21; and Figure 27 illustrates a detail of the body of the syringe of the apparatus of figure 21. DETAILED DESCRIPTION OF THE DRAWINGS Figure 1 illustrates a syringe 2 which includes a plunger handle 4, to which is connected four plunger rods or stems 6. The plunger stems 6 at their other end are connected to a plunger 8. The plunger 8 slides inside syringe body 10. The plunger 8 is suitably shaped to seal against the inner wall 12 of body 10. A flexible conduit 14 is internally positioned with respect to plunger stems 6. The flexible conduit 14 connects the base of plunger 8 to top 16 of syringe 2. The flexible conduit 14 when in the extended position provides smooth sides and thus a passage for needle 60 to be retracted into. Figure 2 illustrates that the body 10 of the syringe 2 has an inner wall 12 and an outer wall 18 and four pre-formed grooves 20 at 90° spacing to each other. Figure 2 being a cross- section through, line HI - LLT also shows the four plunger stems 6 and flexible conduit 14 in the centre thereof. Figure 3 illustrates in more detail the construction of grooves 20 in syringe body 10. The syringe 10 is made of a standard plastic or polymer material on inner wall 12, whilst the outer wall 18 is a much thinner, harder plastic or polymer. Also located in groove 20 is a guide strip 22 which serves to hold in place the scoring blade 24, (see figures 4 and 5), and to keep the blade 24 against outer wall 18. Referring to figure 4, the scoring blade 24 does not score the outer wall 18 on the backward stroke when the syringe 2 is initially being filled with the substance to be injected. Once the required amount has been drawn into the syringe body 10, a series of insertion guides 26 on the wall are located at each of the calibration points 28, for example lml or 2ml. If overfilling has taken place, then providing the scoring blade 24 has not passed another calibration point the blade 24 will not be inserted into insertion guide 26 except in the event of an injection stroke or downward stroke of plunger 8. As illustrated in figure 4 in phantom line, on the downward stroke, the scoring blade 24 enters insertion guide 26 and is then retained against outer wall 18 by guide strip 22 (figure 3). The paring blade 30 runs inside groove 20 at all times. However, it does not fracture or break outer wall 18. The scoring of the outer wall 18 first by scoring blade 24 and then by paring blade 30 perform the task of fully weakening the outer wall 18. The collapse of the outer wall 18 is caused by outside air pressure being exerted on outer wall 18 of syringe body 10, whilst the inner portions of body 10 are subjected to a negative pressure. Referring to figures 1, 7 and 8, a negative pressure is produced behind plunger 8 by the action of the syringe 2. When the plunger 8 is moved in the upward direction this evacuates air in the volume adjacent the valve system 32. When the plunger is moves away from the valve system 32, a negative pressure is formed. The valve system 32 is located in the top 16 of the syringe body 10. The valve system 32 allows air to be expelled and prevents the ingress of air when the plunger 8 is on its downward stroke. The valve system 32 consists of a tapered capillary 34 in which is placed a valve ball 36. Valve ball 36 is biased in its movement by a return band 38 and is limited by a travel limiting lug 40 located inside the capillary 34. As air is passed out of the syringe body 10 valve ball 36 moves out of register with the opening of the tapered capillary 34. On the downward stroke the return band 38 forces valve ball 36 back into register with the tapered capillary 34. Referring to figures 9 and 10, as plunger 8 is moved in the downward direction as illustrated in figure 9, two simultaneous operations occur. Where reference is made to a downward movement this is in a fact a movement to inject the substance into the body of the patient. As the movement in the downward direction occurs, and air is prevented from entering in behind plunger 8, a negative pressure is created behind the plunger 8. This produces an imploding of the walls 12 and 18 in an inward direction. The edge 19 adjacent the groove 20 in figure 2 will move towards the edge 21 on the other side, thereby maintaining the seal and allowing air pressure to continue to act. However, in this process the outer wall 18 is at this point prepared to rent apart by the bending forces which occur when edge 19 meets 21. This will occur at all four grooves 20 around the circumference of body 10. Simultaneously as the walls 18 of body 10 are collapsing they will exert a pressure on plunger 8 as illustrated in figure 10. Air pressure will act via walls 12 and 18 in direction of arrows 42. Because plunger 8 has angled or bevelled trailing surfaces 44, a' forces in direction of arrows 42 is converted into a force in the direction of arrows to produce movement of the plunger 8 in the direction of arrow 46. Because the inner and outer walls 12 and 18 are moving in an imploded fashion, the angle alpha to the vertical of surfaces 44, will tend to push plunger 8 in the downward direction. This in effect means that once the downward stroke begins the plunger 8 will continue in the downward direction. Accordingly a low magnitude force will be required by the operator on handle 4 for the downward stroke. The remaining operations will then happen without need for operator input. Figures 5 and 6 illustrate what occurs when plunger 8 is near to finishing its travel. As plunger 8 moves towards base 48 of syringe body 10, the paring blade 30 and scoring blades 24 will pare and score the complete length of syringe body 10. The plunger 8 having the scoring blade 24 and paring blade 30 approaches base 48 which includes a retaining groove 50. Retaining groove 50 co-operates with a hook 52 on scoring blade 24 which to force the scoring blade 24 to pass through the outer wall 18. At the same time deforming hook 52 also passes through outer wall 18 in groove 50. Once the hook 52 is outside wall 18, it prevents scoring blade 24 from returning into the body of syringe 10. In this way, the plunger 8 is retained in close contact at the very end adjacent to the base of syringe 48. Figure 11, illustrates an operation, which occurs simultaneously with plunger 8 making contact with base 48. When plunger 8 makes contact with base 48, a sealing plug 54 held in the centre of plunger 8 by a flexible retaining membrane 56 is pushed into contact with retaining lugs 58 on needle 60. Mating captive lugs 62 on plug 54 engage retaining lugs 58, thereby holding seal 54 firmly in place on needle 60 and sealing same. This occurs instantly prior to the flexible retaining membrane 56 engaging cutting blades 64, on needle 60. This separates plug 54 from plunger 8. Simultaneously therewith a flexible blade 66 acts to cut retaining seal 68 which holds needle 60 in place on the base 48 of syringe 10. The flexible blades 66 engages seal 68 when the flexible blades 66 make contact with direction surfaces 104 which direct the blades 66 against seal 68. The instant that retaining seal 68 is broken, with plug 54 in place, the needle 60 and plug 54 move back into the body of the syringe internally of conduit 14. Conduit 14 has on the end near top 16 of syringe 10, a valve system 32 similar to that which has been described. This ensures that a negative pressure is produced inside flexible conduit 14 so that the needle 60 will be retracted into the body 10. Illustrated in figure 12 is an alternative means for achieving retraction of needle 60. This alternative means does not require a conduit 14. A spring 72 would be utilised. Plug 74 is linked to spring 72 which in turn is secured at top 16 of syringe 10. As before, captive lugs 62 will engage retaining lugs 58 on needle 60 and once the respective seals are broken the needle 60 and plug 74 will be retracted back into the syringe body 10. If the spring 72 is utilised a vacuum inside the conduit 14 does not need to be produced. Illustrated in figure 13 is a detailed side view a flexible conduit 14 which is schematically depicted in figure 1. The flexible conduit 14 is formed in a concertina fashion when in the unextended position. When a cross section is taken, such as is illustrated in figure 14, the internal shape has the appearance depicted. In the extended position, as illustrated in figure 15, the internal shape is as depicted in figure 16 which is a cross section through figure 15. The side view of conduit 14 is depicted if figure 17. In figures 16 and 17, diamond formations 76 on the side of the flexible conduit 14 are clearly seen. The diamond portions 76 serve to provide surface tension so that when the conduit 14 is in the fully extended position, substantially smooth surfaces 78 appear on the internal walls of conduit 14 as seen in figure 13. As the needle 60 and plug 54 move into conduit 14, the periphery of needle 60 applies a force against the walls of conduit 14 which separates the lower end of conduit 14 from plunger 8 re-admitting air back into the cavity of syringe 10. This equalisation of air pressure forces the collapsed inner wall 12 and outer wall 18, to return to their original shape. When this happens the partial fractures as previously described become full fractures with the snap back shock at these points, thereby paring the syringe body 10 into four distinct parts. As the needle 60 and plug 54 move up through conduit 14 the rear side of plug 54 has an impact plug 80 (see figure 11) which is shaped in such a fashion as to mate with the socket 82 (see figure 7) on top 16 of syringe 10. When the needle 60 and plug 54 are fully retracted impact plug 80 engages socket 82 and is thereby retained in a positive fashion. Illustrated in figure 18 is an arrangement by which a plunger stem 6 passes through the top 16 of syringe 10. Plunger stem 6 passes through a travel guide 84 which includes a sealing means, in this case on O ring 86. the 0-ring 86 need not be a different material to the travel guide 84. It can be made of the same material, or replaced by a formation or projection on the travel guide 84. The travel guide 84 includes a retaining socket 88 and stop lever 90 which co-operate together when the syringe is in the "ready to use" mode as illustrated in figure 1. To prevent accidental disarming of the syringe prior to use, stop lever 90 is biased towards and engages retaining socket 92. In this position (not illustrated) the plunger cannot be accidentally pushed toward the needle end. When the plunger 8 is drawn up, stop lever 90 is forced inside its retaining recess 88 where it remains out of the way during the discharge operation. An alternative arrangement to that of figure 18 is to remove the O-ring 86 and provide a sealing projection as part of the syringe body 10, and to form the stem 6 with a taper so that as the stem 6 moves through the sealing projection, the force of contact increases because of the increasing diameter of the stem 6. This increases the sealing force as the stem 6 moves to the needle end, and this increased sealing force can better handle the increased negative pressure as the stem 6 moves towards the needle end. Illustrated in figure 19 is a detailed view of a portion of the needle 60. The needle 60 terminates in a nozzle 94 and is connected to the main portion of the needle 60 by a capillary ball joint 96 having a ball joint housing 98 and a capillary 100 through it. The ball joint housing 98 also has associated with it an O ring seal 102 at an upper and lower portion of the ball joint. The apparatus illustrated in figure 19 is designed to prevent the use of the syringe as a weapon in that as soon as any non-longitudinal forces (with respect to the direction to the needle) act upon the nozzle 94, nozzle 94 will rotate out of register with the longitudinal axis of the needle 60 (see figure 20), thereby forcing capillary 100 to be located between upper and lower seals, thus terminating the ability of the needle 60 to allow passage of fluid there through. Illustrated in figure 21 is a second embodiment of the present invention, and like features are labelled with the same numbers as in figures 1 to 19. The syringe of figures 21 and 22 is constructed in much the same way as that of figures 1 to 19 but the syringe has some modifications thereto. The syringe 2 of figures 21 and 22 has a plunger handle 4 which connects with plunger 8 by means of plunger rods or stems 6. The plunger 8 is illustrated in more detail in figures 23 and 24. The plunger 8 has a chamfered edge 114 on the handle side of plunger 8. A sealing plug 54 is centrally located and is surrounded by a series of circumferentially positioned cutting means 66 which are in expanded form. The cutting means 66 is shown in figure 25 and illustrates how the cutting means 66 interacts with the needle 60 and its corresponding mounting assembly. The needle 60 mounting assembly includes a direction means 104 which pushes the blades 66 towards the seal 68 to thereby cut all around and thus release needle 60. The cutting means 64 on needle 60 cuts the seal 106 retaining plug 54 to plunger 8. This action occurs whilst the plug 54 enters the needle 60 and is held in place by the shoulder 108. Illustrated in figure 21 and in more detail in figure 26, the syringe 2 utilises valve balls 36 to control the passage of air and maintain a negative pressure in the syringe body 10, after the plunger 8 has been fully withdrawn. The valve ball 36 includes a bias means in the form of a leaf spring 38, which seals the tapered capillaries 34. A portion of the body 10 is illustrated in more detail in figure 27. The embodiment of figures 19 to 20 utilised a collapsible side wall which was destroyed by the plunger moving down. In this embodiment, the body 10 has deformations or corrugations 110 and 112 which are located on the outer and inner surfaces of the body 10 to give the body 10 sufficient flexibility to allow a collapsing thereof in response to a negative pressure. This collapsing helps to produce the involuntary disablement of the syringe 2 in the same fashion as that of figures 1 to 19, without the need for scoring and paring. The corrugations 110 and 112 are circumferential. The outside corrugations 110 are offset from the inside corrugations 112 by i a width of a corrugation. Typically the size of the corrugations are 0.2mm in radius or 0.4mm in diameter. However any corrugations of the order of 0.05mm to 0.8mm in radius can be used. Depending on the size of the corrugations, the wall thickness may need to vary in order to produce the necessary coUapsibility. The internal corrugations 112 interact with the chamfer 114 to force the plunger 8 to move towards the needle 60 as the wall 10 collapses due to the negative pressure produced. This operation is similar to that as described in figures 9 and 10. The disablement of the syringe 2 is by a which includes the disabling steps of the formation of a bias (either a negative pressure or a spring bias formed by spring 72 or a combination of both) by the movement of the plunger 8 in the direction of a needle 60 end of the syringe 2. The bias retracts the needle 60 into the syringe body 10 when the plunger 8 reaches the needle end. The bias results in the collapse of the body 10 behind the plunger 8 helps to force the plunger 8 in the direction of the needle 60 end of syringe 2. When the bias is a negative pressure it is produced in association with at least one one way valve located in the body 10. The method of disablement of syringe 2 also includes the step of plugging the needle 60 with a plug 74, immediately after which or simultaneously with the separating of the needle 60 from the body 10. Whilst the foregoing embodiments are separately described, features of one embodiment can be used together with some or all of the features of the other embodiment. Such combinations of features can be illustrated in a non limiting way by means of, for example, the corrugations 110 and 112 can be used with the embodiment of figures 1 to 17. Whilst the foregoing describes several embodiments of the present invention and modifications can be made thereto without departing from the scope of this invention.

Claims: THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS: 1. A syringe including a plunger adapted to slide in a body, said syringe being characterised by said body being collapsible behind said plunger when said plunger is pushed into said body, towards a needle end of said body. 2. A syringe as claimed in claim 1 wherein said body has at least one longitudinal line of weakness. 3. A syringe as claimed in claim 1 or 2 wherein said plunger includes at least one scoring means which aids said body to collapse along said line of weakness by a negative pressure produced by said plunger as said plunger moves towards the needle end. 4. A syringe as claimed in claim 3 wherein said plunger also includes a paring blade. 5. A syringe as claimed in any one of claims 2 to 4 wherein said scoring means only engages the lines of weakness at predefined intervals defined by calibrations on a surface of said body. 6. A syringe as claimed in claim 1 wherein said body has at least one lateral line of weakness. 7. A syringe as claimed in claim 1 or 6 wherein said body includes a series of deformations on said body. 8. A syringe as claimed in claim 7, wherein said deformations are on internal and external surfaces of said body. 9. A syringe as claimed in claim 7 or 8, wherein said deformations have a rounded profile. 10. A syringe as claimed in claim 7, 8 or 9, wherein said deformations are circumferential in nature. 11. A syringe as claimed in any one of claims 7 to 10 wherein deformations which are internally and externally located are offset. 12. A syringe as claimed in claim 11, wherein said internal and external deformations are 0.05mm to 0.8mm in radius. 13 A syringe as claimed in any one of the preceding claims wherein said syringe includes a needle at said needle end, said needle being is retracted by bias produced when said plunger is moved in a direction towards said needle. 14. A syringe of the retractable needle type as claimed in claim 13, being further characterised by said plunger including a detachable seal means to engage said needle and seal it. 15. A syringe of the retractable needle type as claimed in claim 14, wherein said needle and said seal means retract into a cavity in said plunger. 16. A syringe of the retractable needle type as claimed in any one of claims 13, 14 or 15, wherein said bias is formed by a negative pressure produced behind said plunger, as said plunger moves towards said needle. 17. A syringe of the retractable needle type as claimed in any one of claims 13, 14 or 15, wherein said bias can also be created by a spring means only, or a spring means together with a negative pressure. 18. A syringe of the retractable needle type as claimed in any one of claims 13 to 17, wherein said needle, is retracted to a position and held in said position in a positive manner. 19. A syringe of the retractable needle type as claimed in any one of claims 13 to 18, wherein said plunger includes a cutting means to separate said needle from the body. 20. A syringe as claimed in claim 19, wherein said cutting means is circumferential. 21. A syringe of the retractable needle type as claimed in claim 20, wherein said cutting means, when not in use, is in expanded form. 22. A syringe of the retractable needle type as claimed in any one of claims 19 to 21, being characterised by said cutting means, as it nears a seal holding said needle in said body, is directed to cut said seal by direction means. 23. A syringe of the retractable needle type as claimed in claim 22, wherein said direction means is circumferentially located around said needle. 24. A syringe of the retractable needle type as claimed in claim 22, wherein said direction means also includes an inclined plane to make said cutting means engage and cut said seal. 25. A syringe as claimed in any one of claims 19 to 24 wherein said needle has a plug release means to release a plug on said plunger, said needle including a securing means to secure said plug into said needle. 26. A syringe of the retractable needle type as claimed in claim 25, wherein said securing means is a circumferentially configured barbs or radially configured barbs. 27. A syringe as claimed in any one of the preceding claims wherein said body including at least one one-way valve, that allows air to escape from said body when said plunger is drawn back, said valve preventing ingress of air when said plunger is moved towards said needle. 28. A syringe of a single use type as claimed in claim 27, wherein said plunger includes a cavity defined by a flexible conduit. 29. A syringe of a single use type as claimed in claim 28, wherein said conduit is of a concertina type construction, and when in the extended position, has a substantially smooth surface. 30. A syringe of a single use type as claimed in any one of claims 27 to 29, wherein said one way valve includes a tapered valve body which is selectively sealed by a biased circumferential valve element. 31. A syringe of a single use type as claimed in any one of claims 27 to 29 or 30, wherein said valve has a valve element therein. 32. A syringe of a single use type as claimed in any one of claims 27 to 31, wherein said valve has a valve element which is a ball attached to a leaf spring to bias said valve element to shut off said valve. 33. A syringe as claimed in any one of the preceding claims, wherein said syringe includes a needle having a passage therethrough and an articulated tip including an upper and a lower sealing ring, said tip including a capillary extending beyond said lower and said upper sealing ring, such that any non-longitudinal force exerted on said tip will rotate said tip, thereby closing the passage in said needle. 34. A syringe as claimed in any one of the preceding claims, wherein said plunger has a stem which passes through the boy of said syringe, said stem being slidably sealed relative to said body. 35. A syringe as claimed in claim 34 said stem is of a tapered construction to enable an increased sealing force to be applied as the stem moves through the syringe body. 36. A syringe as claimed in claim 34 or 35, wherein said stem of the plunger has a disengageable securing means, to selectively allow operation of the syringe. 37. A method of disabling a syringe, said syringe including a body, plunger and needle, said method including the steps of: forming a bias by the movement of the plunger in the direction of a needle end of said syringe; and retracting said needle into said body, by said bias, when said plunger reaches said needle end. 38. A method of disabling a syringe as claimed in claim 37, wherein said step of forming said bias results in the collapse of the body behind the plunger forcing said plunger in the direction of said needle end. 39. A method of disabling a syringe as claimed in claim 37 or 38, wherein said method also includes a step of plugging said needle. 40. A method of disabling a syringe as claimed in claim 37 or 38 or 39, wherein said method includes a step separating said needle from said body, by said plunger moving to the limit of its travel.

Inventors: SUTTON STEVEN MICHAEL, SUTTON, STEVEN, MICHAEL
Applicants: SUTTON STEVEN MICHAEL, SUTTON, STEVEN, MICHAEL
Application year: 1995
Main classification: A61M5
IPC codes: A61M5