Device for ejecting the removable tip of a pipette

Abstract

A pipette intended to be used with ejectable tips push fitted onto the pipette which is also provided with a tip ejecting device. The device comprises a thumb actuable push button which on depression, against upward spring pressure, pushes down a rod. In turn the rod pushes down a limb attached to the rod. The limb is cranked to conform to the shape of the pipette and has a lower end formed as a sleeve normally surrounding the lower end of the pipette just above the ejectable tip so that downward movement of the sleeve pushes the tip off. The limb is detachable from the rod, and the sleeve can be slipped off the end of the pipette so that the limb may be washed.

What is claimed is: 
     
       1. Device for ejecting the removable tip of a pipette, .[.the.]. .Iadd.a .Iaddend.lower .Iadd.tubular .Iaddend.end of which terminates in the form of a conical part intended to receive said removable tip by friction, in particular of a micro-pipette, .[.characterised.]. .Iadd.characterized .Iaddend.by the fact it comprises in combination: a rod which is incorporated in a passage provided in the body of the pipette, said passage and said rod being arranged so as to be able to impart to the latter a movement of translation parallel to the axis of the pipette;   means allowing said rod to move along a certain path limited in the upwards and downwards direction;   resilient means permanently urging said rod in an upwards direction;   a removable ejection member comprising an upper part, a central part and a lower end, said upper part being removably fitted together with the lower part of said rod in an abutment relationship, said central part being located in the vicinity of the pipette, and said lower end terminating in the form of guiding and ejection means in order to surround at least partly the lower tubular end of the pipette in the vicinity of its conical part, the lower end of said ejection member in its upper position not reaching the upper limit of the removable tip when the latter is put in position by friction.Iadd., .Iaddend.   .Iadd.at its upper end, the rod comprises a push button which, when actuated, moves the ejection member downwards thus causing the ejection of the removable tip, the rod also comprises, in the vicinity of its upper end and below the push button, a stop-ring fulfilling the function of an upper abutment for said resilient means comprising a coil spring surrounding said rod, said spring bearing by its lower end against a shoulder provided in the passage of the pipette body.Iaddend..   
     
     
       2. Device according to claim 1, .Iadd.characterized .Iaddend..[.characterised.]. by the fact that the removable ejection member terminates in the form of an upper tubular end in order to be able to fit together with the corresponding lower .Iadd.cylindrical .Iaddend.part of said rod. .[.3. Device according to claim 1, characterised by the fact that, at its upper end, the rod comprises a push button which, when actuated, moves the ejection member downwards thus causing the ejection of the removable tip..]. .[.4. Device according to claim 3, characterised by the fact that the rod comprises, in the vicinity of its upper end and below the push button, a stop-ring fulfilling the function of an upper abutment for a coil spring surrounding said rod, said spring bearing by its lower end against a shoulder provided in the passage 
     
     
        of the pipette body..]. 5. Device according to claim .[.4.]. .Iadd.1.Iaddend., .[.characterised.]. .Iadd.characterized .Iaddend.by the fact that the rod .Iadd.and movement allowing means .Iaddend..[.comprises.]. .Iadd.comprise .Iaddend.a .[.stop ring.]. .Iadd.stop-ring .Iaddend.limiting the downwards travel of said rod by co-operation with a corresponding shoulder provided in said passage of the 
     
     
        pipette body. 6. Device according to claim 5, .[.characterised.]. .Iadd.characterized .Iaddend.by the fact that the stop-ring fulfilling the function of an upper abutment for said .[.coil.]. .Iadd.resilient means comprising a coil .Iaddend.spring and the ring limiting the downwards 
     
     
        travel of said rod are constituted by the same part. 7. Device according to claim 6, .[.characterised.]. .Iadd.characterized .Iaddend.by the fact that said rod .Iadd.and said movement allowing means .Iaddend..[.comprises.]. .Iadd.comprise .Iaddend.a stop-ring limiting its upwards travel by co-operation with .[.the.]. .Iadd.a 
     
     
        .Iaddend.corresponding shoulder. 8. Device according to claim 1, .[.characterised.]. .Iadd.characterized .Iaddend.by the fact that in the vicinity of its lower end, said rod is provided with a circlip intended to limit the engagement depth of the ejection member on the lower part of the 
     
     
        rod. 9. Device according to claim 1, .[.characterised.]. .Iadd.characterized .Iaddend.by the fact that in the vicinity of its lower part, the rod comprises an annular groove intended to receive a keeper ring co-operating with an annular groove in the ejection member in order 
     
     
        to connect these two parts. 10. Device according to claim 2, .[.characterised.]. .Iadd.characterized .Iaddend.by the fact that the ejection member whose upper part and lower .[.part.]..Iadd.end .Iaddend.are respectively in the form of a hollow tube and sleeve, is formed from a metal sheet having an appropriate cut-out. .Iadd.11. A device for ejecting the removable tip of a pipette, a lower tubular end of which terminates in the form of a conical part intended to receive said removable tip by friction, in particular of a micro-pipette, characterized by the fact it comprises in combination: a rod which is incorporated in a passage provided in the body of the pipette, said passage and said rod being arranged so as to be able to impart to the latter a movement of translation parallel to the axis of the pipette;   means allowing said rod to move along a certain path limited in the upwards and downwards direction;   resilient means permanently urging said rod in an upwards direction;   a removable ejection member comprising an upper part, a central part and a lower end, said upper part being removably coupled with the lower part of said rod, said central part being located in the vicinity of the pipette, and said lower end terminating in the form of guiding and ejection means in order to surround at least partly the lower tubular end of the pipette in the vicinity of its conical part, the lower end of said ejection member in its upper position not reaching the upper limit of the removable tip when the latter is put in position by friction, said rod includes a push button at the upper end of said rod and a stop-ring in the vicinity of the upper end of said rod and at the bottom of said button fulfilling the function of an upper abutment for said resilient means comprising a coil spring surrounding said rod, said spring bearing by its lower end against a shoulder provided in the passage of the pipette body. .Iaddend. .Iadd.12. The device according to claim 11 wherein said lower end of said removable ejection member completely surrounds the lower tubular end of said pipette and extends upward from said lower tubular end of said pipette at least a distance sufficient to strengthen said lower end of said removable ejection member to prevent bending upon engagement with said removable tip. .Iaddend. .Iadd.13. The device according to claim 11 wherein said upper part of said ejection member being removably connected to said rod at a location relative to said passage in said body of said pipette to allow access for removal. .Iaddend. .Iadd.14. The device according to claim 11 said movement allowing means further comprising a stop-ring secured to said rod and limiting upward travel of said rod by engagement with the body of said pipette. .Iaddend.