referring now in detail to the invention , particularly as disclosed in the embodiment of fig1 through 5 of the drawings , and especially as shown in fig1 there is disclosed a needle locking and catheter hub unlocking mechanism 10 . the leading or forward end 12 of a needle or cannula guarding housing 14 includes a cavity 16 containing a bag or a bellows 18 , shown in a folded - together or compressed condition . extending centrally and forwardly out from the housing 14 through a guide sleeve 20 is a cannula or hollow needle 22 adapted to form a venipuncture in a patient , and which also passes through a central aperture 24 formed in a latching element 26 constructed pursuant to the invention . the extended cannula 22 then passes through a catheter hub 28 possessing a luer lock lug structure 30 , which encompasses a nose piece 32 and gasket 34 contained therein . the leading end of the cannula or hollow needle 22 is adapted to be introduced into the body of a patient ( not shown ) for imparting a venipuncture for the administering of suitable fluids introduced through a catheter ( not shown ) encompassing and advanced into the puncture along the outer surface of the cannula ( not shown ). the catheter may be a flexible tubular member terminating at one end in the catheter hub 28 , as is well known in the technology , and upon forming of the venipuncture by the tip of the cannula or hollow needle 22 is adapted to be slipped forwardly thereover into the patient while the needle or cannula 22 is adapted to be retracted from the catheter into the protective housing 14 . the latching element 26 for the needle locking and catheter hub unlocking mechanism , as shown in fig3 to 5 , comprises a lever - shaped member having a central plate portion 36 having the aperture 24 through which the cannula 22 is inserted to project forwardly during the locked condition of the components ; with the plate portion 36 being located at an incline with one forwardly extended end of the plate portion 36 including a t - shaped structure 38 . one arm 40 of the t - shaped structure engages a protruding tab arrangement 42 on the front surface of the housing 14 containing the folded or compressed bag or bellows ; whereas the other arm 44 of the t - shaped structure 38 includes a hook - like projection 46 forming a recess 48 into which there engages a lug 50 of a luer lock forming an integral component of the catheter hub 28 so as to maintain the components in their interlocked condition as shown in fig1 of the drawings . upon the venipunctural insertion of the tip portion of the needle or cannula 22 into the body of the patient and the sliding forwardly thereover of the flexible tubular catheter into the site of the puncture , the cannula 22 is retracted , as shown in fig2 of the drawings , while leaving the catheter in place . as the cannula 22 is retracted from the catheter through the central aperture 24 in the plate portion 36 of the latching element 26 for the catheter hub 28 , the spring or biasing action of the plastic material of the t - shaped structure causes it to pivot or bend at location 54 so as to cause the aperture 24 to be displaced upwardly and the plate portion 36 forming a barrier preventing the tip of the retracted cannula 22 from extending beyond the nose guard portion of the housing . simultaneously , the bending action of the plate portion 36 disengages the luer lug 50 from the recess 48 in the opposite arm 44 of the t - shaped element , resultingly releasing the catheter hub 28 and thereby enabling the cannula components and guard housing 14 with the retracted cannula therein and the attached needle locking and catheter hub unlocking mechanism to be removed so as to provide for the capability of connecting a cooperating luer lock structure ( not shown ) to the catheter hub 28 enabling the administering of parenteral fluids , blood or medications to the patient through the catheter in the venipuncture which remains attached to the catheter hub 28 . the mechanism 10 comprising the t - shaped plate element , as shown in fig3 through 5 of the drawings , includes a lip 58 having the recess 48 formed therein for retaining the luer lock lug 50 and with the distal end 60 of the plate portion 36 member which includes the aperture 24 for the passage therethrough of the cannula 22 including a snap tab 60 which will prevent the plate 36 from completely popping free and falling off upon release caused by the withdrawal of the tip of the needle . this structure essentially provides a secure guarding mechanism for the cannula 22 needle and retains the catheter hub 28 secured thereto until after the guarding mechanism comprising the t - shaped element 38 is securely positioned over the tip of the withdrawn cannula 22 . the mechanism simultaneously releases the catheter hub 28 and guardingly covers the tip of the used cannula 22 , possibly generating a loud &# 34 ; click &# 34 ; noise to provide audio indication that the cannula is secured against external contact and the catheter components are separated therefrom . the elements forming the mechanism 10 may be constituted of suitable plastic material , such as acetyl or the like , and essentially forms a so - called &# 34 ; trigger &# 34 ; upon the tip of the retracted cannula 22 clearing the cannula aperture 24 formed in the plate - shaped portion 36 of the mechanism , simultaneously guarding the retracted cannula and releasing the catheter hub 28 . referring to the diagrammatically shown embodiment of fig6 and 7 of the drawings ; wherein similar elements as in fig1 are identified by the same reference numerals ; in essence , the mechanism 70 for disengaging the catheter hub 28 from the housing 14 may also be constituted of a plastic plate - shaped component 72 having a recessed hook portion 74 at one end 76 , and wherein the plastic material is of a resilient formable nature . the hook portion 74 is interconnected to the catheter hub by means of engaging over a luer lock lug 50 through a so - called &# 34 ; fishline &# 34 ; or coiled tether 78 attached at 80 to a projection 82 on component 72 , and at an opposite end to a flange 84 on the housing 14 device . the tether 78 is essentially in a loosely coiled position in the extended - needle condition , and when the cannula 22 is retracted , with a cannula guard comprising a folded bag or compressed bellows 86 located between the housing 14 and a guard nose being fully extended so as to cause the needle tip of the cannula to be withdrawn therein , the resultingly extended &# 34 ; fishline &# 34 ; tether 78 deforms or bends the component 72 , so as to release the luer lock lug 50 on the catheter hub 28 , as shown in fig7 enabling the catheter hub 28 to be separated from the cannula assembly comprising the housing 14 and the mechanism 78 and 72 . the used cannula 22 is contained within the extended bag or bellows , and thus secured and guarded against potential contact by a physician or clinical personnel . as shown in the embodiment of fig8 through 10 of the drawings , which is somewhat similar to that of fig6 and 7 , a thin pair of tethers 90 form a single loop member 92 constituting two legs of a loop interconnects a housing 94 and a catheter hub with a luer lock lug . attached to the components extending between the housing 94 and a nose or guard member 100 is a thin flexible bag 102 which , upon retraction of the cannula 22 , incorporates a guard for the retracted cannula and its needle tip . hereby , the device forming the tether may be of a thin - walled structure , as shown in fig9 which as attached offset from a central axis will prevent rotation or torqueing between the components during operation , in effect , prevent rotation of the nose / guard member 100 relative to the housing 94 while firmly anchoring the former to the latter . as shown in fig1 and 11 , the tethers 90 forming the two legs of a loop 92 may be manufactured by molding , stretching and orienting techniques to produce a very strong linearly - oriented plastic material tether . various plastics , including polyolefins and nylons readily lend themselves to this particular molding technique . the tether is adapted to be attached to the housing 94 and , respectively the nose / guard member 100 , and folded into a compartment beneath the housing . particularly as shown in fig1 of the drawings , illustrating a tether hold - down structure 110 connected to a compressed bag or tube 112 in the housing , this evidences that the tether may be coiled together in position below a blood chamber 116 , as shown in the representation of fig1 of the drawings . pursuant to the schematically represented embodiment of fig1 and 15 , this shows a somewhat modified structure of the arrangement of fig1 , whereby in this instance , the tether 120 may be a mylar or film strip having a hole 122 formed in the center thereof to enable passage therethrough of the cannula 22 , the latter of which extends through a needle tip protector 124 and luer lock 126 , and upon cannula retraction causes the mylar strip to be biased towards the cannula by both the needle tip protector and the housing components in order to maintain itself alongside the cannula , as the cannula traverses the tip protector during retraction . as illustrated , the attachment of the mylar strip may be mechanical in nature , such as by a snap fit , heat staking or other standard means of attachment . the particular use of two strips of mylar also prevents or resists torqueing or rotation of the needle tip protector relative to the housing portion of the arrangement . from the foregoing , it becomes readily apparent that the invention is directed to novel and unique mechanisms for simultaneously locking a cannula and unlocking a catheter hub while providing for protection for a retracted cannula . while there has been shown and described what are considered to be preferred embodiments of the invention , it will , of course , be understood that various modifications and changes in form or detail could readily be made without departing from the spirit of the invention . it is , therefore , intended that the invention be not limited to the exact form and detail herein shown and described , nor to anything less than the whole of the invention herein disclosed as hereinafter claimed .
a catheter needle tip protector and a safety mechanism which provides fail / save protection to clinical personnel against the possibility of accidental punctures by a used intravenous needle through the provision of automatic catheter needle tip protecting structure which becomes operative upon withdrawal of the needle from the body of a patient .