the present invention resides in a needle assembly that do not utilize a compressible spring device for moving or locking a sleeve that covers the sharp distal tip of the needle . this needle assembly includes a needle holder 1 , a needle sleeve 2 and an interlocking member 3 as shown in fig1 . in this invention , the distal end is the point away from the operator while the proximal end is the point close to the operator during the use of this device . the shape of the needle assembly is preferably rectangular for ease of handling . the needle holder 1 is shaped like an open trough with a horizontal extension or a scoop as shown in fig2 . it has an open lateral distal end 4 and a closed walled proximal end 5 , a walled first 6 and second 7 longitudinal sides , a solid base 8 , a hollow top surface 9 and a protrusion 10 . the needle holder may be made of glass , metal or plastic but is preferably made of plastic polymeric material such as polyvinyl chloride , polyethylene , polypropylene , nylon , polycarbon , polysulfone , and the like . the protrusion 10 at the distal end of the needle holder extends radially outward from the outer surface of the longitudinal walls along the longitudinal sides 6 and 7 at the distal end of the needle holder . the protrusion 10 is preferably slanted , with the thicker end towards the proximal end and is also preferably made of the same polymeric material as the body of the needle holder . the solid base 8 is approximately half of the depth of the needle holder as shown in fig2 . the walls along the longitudinal sides 6 and 7 has an overhang 12 bordering the entire length of the longitudinal walls and extending internally , that is , inwardly towards the interior of the needle body . the wall that borders the proximal lateral end 5 , extends slightly pass the longitudinal walls 6 and 7 to cause a protruding fence 13 which can be either on one side or on both sides of the proximal lateral end 5 . the distal lateral end 4 is left open . embedded on the upper portion of the solid base 8 close to the hollow top surface 9 is a metallic needle 14 with the distal end protruding from the needle holder 1 as shown in fig2 . the needle has a hollow interior , lumen 17 and could vary in sizes and gauge . the proximal end of the needle 14 is permanently mounted to one end of a connector 15 which is preferably made of the same polymeric material as the needle holder . a connector with a luer lock tip 18 at the other end not connected to the needle is preferred . the walls of the connector may be in line with the longitudinal sides of the needle holder or may be recessed as shown in fig1 . the connector 15 has a hollow conical interior , a cone shaped cavity , that tapers and converge with the proximal base of the hollow metallic needle 14 so as to communicate with the lumen 17 of the needle , through which materials , preferably liquids or suspensions , may be introduced . the needle assembly is commonly mounted into a hypodermic syringe or other fluid delivery source or reservoirs used and known in the medical field . the needle assembly is preferably mounted on a syringe body with a luer lock adapter . the protrusion 10 that extends radially outward from the outer surface of the walls covering longitudinal sides 6 and 7 at its distal end functions both as a locking device and an engagement device with the needle sleeve 2 . an interlocking member 3 as shown in fig3 slips or snaps into the hollow top surface of the needle holder and is held inside the hollow top surface 9 by the overhang 12 along the longitudinal walls 6 and 7 as shown in fig4 . the interlocking member is solid . it can be made of metal or hard rubber but is preferably made of the same preferred polymeric material used for the needle holder 1 but is of a kind that is non - brittle , durable and resilient with memory . with memory means the material will return to its original configuration when the restraining means which keeps the material stationary at a strained position , is released . the proximal portion 19 of the interlocking member is planar with a recess 20 along its longitudinal edges 21 as shown in fig3 . the recess 20 abuts and fits underneath the overhang 12 of the needle holder 1 . the outer surfaces of the recess 20 and the overhang 12 are shaped to match each other and are of the same dimensions to allow a good fit . they are preferably planar . the distal portion of the interlocking member 3 extends upwardly at an angle , hereinafter referred to as angular end 22 , from its planar proximal end 19 . the angular end 22 has a width narrower than the planar end 19 . the angular end has no recess along its longitudinal edges 23 . the angular end is also of such width that its longitudinal edges 23 just freely rub on the longitudinal inside tip of the overhang 12 , allowing unimpeded up and down motion of the angular end 22 . at the distal portion of the angular end 22 is a second stepped recess which look like a fore and middle finger projection , hence will be referred to as finger hook 24 . the finger hook has a notch 16 . the needle sleeve 2 is shaped to conform with the outer contour and surface of the needle holder 1 . it is preferably shaped like a hollow rectangular box , as shown in fig5 with an open proximal 25 and distal 26 lateral ends to allow the needle sleeve 2 to slide over the needle holder 1 in a telescopic manner relative to the needle holder . the closed sides of the needle sleeve are the longitudinal side walls 28 and 29 and the top and bottom surfaces 30 and 31 . the top surface 30 has a cutout area 32 , preferably rectangular in shape as shown in fig5 . the cutout area has three sides , two horizontal sides 34 and 35 and a frontal side 36 . all three sides may be blunt ended but it is preferable for the frontal side 36 to have a slant edge as shown in fig4 . the cut out area leaves a horizontal overhang 33 which rests over the overhang 12 of the needle holder 1 , the overhang 12 functions like a track over which the sleeve traverses to and from . at a calculated or measured distance , starting approximately a third of the full length of the needle sleeve 2 from the proximal end 25 , are grooves 27 along the inner surface of the longitudinal walls . these grooves engage with the protrusion 10 and function as a track ( shown in broken line ) through which the protrusion 10 can traverse to and from horizontally as shown in fig6 . the outer surface of the longitudinal walls 28 and 29 of the needle sleeve may be smooth or gridded . however , it is preferable to grid all the outer sides of the walls to provide a better grip for the user as shown in fig7 . the needle sleeve can also be made of metal or glass but is preferably made of the same polymeric material as those used for the needle holder and interlocking member . when the sliding needle sleeve 2 is slid over the top surface of the needle holder from a position covering the needle holder as shown in fig8 to a direction towards the tip of the needle 14 , the leafspring action of the angular end 22 allows the finger hook to rest on the inside wall of the top surface 30 of the sliding needle sleeve and the notch 16 to rest on its frontal side 36 as shown in fig1 . at this position , the entire needle is shielded and the sleeve is temporarily locked . leafspring effect is the counter effect produced when the upward distal end of the interlock member is pressed downward while the planar proximal end 19 is kept stationary in one position . the needle assembly with the needle sleeve 2 in this forward position , shielding the needle 14 , is temporarily locked in this position by the finger hook 24 abutting on the frontal side 36 of the cutout area afforded by its leafspring effect . the finger hook 24 protrudes over the top surface 30 thereby preventing the needle sleeve 2 from moving away from the direction of the needle , as shown in fig1 . on the other hand , the forward motion of the needle sleeve 2 towards the direction of the needle is checked when the protrusion 10 abuts at the end 37 of the groove 27 as shown in fig6 . the grooves 27 prevent the needle sleeve 2 from disengaging with the protrusion 10 of the needle holder . the procedure for exposing the distal tip of the needle 14 from a position where the needle sleeve 2 shields the entire needle body is accomplished by pressing on the top surface of the finger hook 24 downward , towards the hollow top surface 9 of the needle holder , to release its engagement from the frontal side 36 . once the finger hook 24 no longer abuts on the frontal side 36 , the needle sleeve can be manually moved rearward or slid rearward in a direction away from the needle , thereby exposing its distal end as shown in fig8 . at this position , the needle is free for usage for any purpose such as injection , infusion , pricking and the like . the needle sleeve 2 is kept from moving forward or rearward during its use by the slightly flaired edge 11 at the outside junction between the longitudinal walls 6 and 7 and the fence 13 . further , since the inside surface dimensions of the needle sleeve is barely larger than the outer surface dimensions of the needle holder , only enough to allow it to slide over the needle holder , there is also provided a frictional resistance to unassisted motion . the protruding fence 13 on one or both sides of the proximal end 5 of the needle holder also stops any further rearward motion of the needle sleeve 2 . after use , the needle sleeve 2 is merely pushed forward to a position wherein the finger hook 24 reengages automatically with the frontal side 36 because of the angular design and leafspring effect of the distal portion of the interlock member . this process allows one to manually slide with ease , the needle sleeve 2 , forward and rearward in relation to the needle holder 1 , to cover and uncover the sharp distal end of the needle 14 without the use of a spring device and complex mechanisms . for packaging , shipping or when discarding the needle assembly after use , it is preferable to incorporate a capping component 38 for covering the distal and the proximal end of the needle assembly to further prevent accidental puncture or scratching with the tip of the needle . the cap can be made of metal or glass but is preferably made the same polymeric material as those used for the other components of the needle assembly . as shown in fig1 it is sufficient to have only one cap covering the open distal end of the needle assembly if the entire assembly , for example , will be packaged inside a pouch or container . if only one cap is used , the cap 38 extends preferably from the distal tip of the needle sleeve to a position in front of the finger hook 24 which protrudes over the needle sleeve 2 when the needle assembly is stored or discarded as shown in fig1 . the inner wall of the cap 38 is thicker at its distal end than at its proximal end to cause the cap to receive and fit snugly into the needle assembly thereby preventing the cap 38 from unassisted slippage as shown in fig8 . due to the simplicity in design of the needle assembly and the availability of needles and suitable plastic materials at rather reasonable prices , this device can be made available as a disposable product for one time or limited time usage . while the embodiment of the present invention has been described , it should be understood that various changes , adaptations , and modifications may be made therein without departing from the spirit of the invention and the scope of the appended claims .
a needle assembly with a needle holder , a needle sleeve movable over the needle holder , and an interlocking member . the needle sleeve encloses a needle holder and is manually extendable and retractable in a telescopic manner to enclose or expose respectively the distal sharp portion of a needle without the aid of a spring or spring - like device . in this assembly , the needle attached to a connector is embedded into the needle holder to prevent movement of the needle during use . temporary locking and release means are provided which are simple and inexpensive in design .