Pipettes

Abstract

A manual pipette adapted to use disposable plastic tips into which a liquid is drawn and from which it is dispensed is provided with means for dislodging the tip from the pipette after use. The disposable tip which is normally frictionally held at the distal end of the pipette is pushed off the pipette by a sleeve member that is slideably mounted on the barrel of the pipette.

What is claimed is: 
     
       1. A manual pipette adapted to have a disposable tip wedge fitted at one end thereof and in co-axial relationship thereto, the arrangement being such that a disposable tip is secured to the pipette only by the frictional force of the wedge fit, said pipette comprising .Iadd.a piston operating member that is actuated to draw a liquid into and discharge it from a disposable tip, .Iaddend.a detipping member for removing a disposable tip that is wedge fitted to the pipette, said member being slideably mounted on said pipette in a direction parallel to the axis of the pipette and movable between a normal position away from a disposable tip and a position where it engages the end of a disposable tip and thereafter pushes the tip in an axial direction to free it from frictional engagement with the pipette .Iadd., resilient means for biasing said detipping member to its normal position, and means adjacent the end of the pipette remote from the end to which a disposable tip is fitted and proximate to said piston operating member for effecting a relative movement between said detipping member and a disposable tip fitted to the pipette whereby one handed operation of the pipette is facilitated when going from a pipetting to a detipping operation. .Iaddend..[.2. A manual pipette according to claim 1 including resilient means for biasing said 
     
     
        de-tipping member to its normal position..]. 3. A manual pipette according to claim 1 wherein said .[.de-tipping.]. .Iadd.detipping .Iaddend.member 
     
     
        is a sleeve member concentric with the pipette. .[.4.  A manual pipette according to claim 3 including spring means for biasing said sleeve member 
     
     
        to its normal position..]. 5. A manual pipette according to claim .[.4.]. .Iadd.3 .Iaddend.wherein said pipette comprises an elongated tubular member on which a disposable tip is wedge fitted, a finger grip member connected to said elongated tubular member, a plunger assembly mounted within said finger grip member for sliding movement between two stop positions, .[.an adjustment means for determining use of said positions,.]. means for biasing said plunger assembly to .[.the position determined by said adjustment means.]. .Iadd.one of said stop positions.Iaddend., and wherein said sleeve member biasing spring means is a compression spring fitted over said tubular member, and including means secured to said tubular member for restraining one end of said compression spring while its remote end bears against said sleeve member and urges 
     
     
        said sleeve member to its normal position. 6. A manual pipette according to claim 5 .Iadd.including adjustment means for determining one of said stop positions, .Iaddend.wherein said adjustment means is adjustable connected to said finger grip member .Iadd.and said biasing means biases said plunger assembly to the stop position determined by said adjustment means, .Iaddend.and including locking means for securing said adjustment 
     
     
        means in its adjusted position. 7. A manual pipette adapted to have a disposable tip wedge fitted at the end thereof, said pipette comprising a permanent tip member, a sleeve member within which said permanent tip member slides and from which said permanent tip member projects, and spring means for biasing said permanent tip member to its projected position whereby when a disposable tip is being wedge fitted to said permanent tip member as by the pipette being held by said sleeve member and said permanent tip member pressed into engagement with a disposable tip, the force urging said permanent tip member into engagement with the 
     
     
        disposable tip is determined by said spring means. 8. A manual pipette according to claim 7 wherein said permanent tip member projects from said sleeve member by a predetermined distance so that when a disposable tip is being wedge fitted to said permanent tip member the end of said sleeve member will engage the end of the disposable tip and the force urging said permanent tip member into engagement with the disposable tip will be determined and limited by said spring means and its amount of compression. 
     
     
        . A pipette adapted to have a disposable tip mounted at one end thereof, said pipette comprising, a permanent tip member to which a disposable tip is frictionally joined so as to form an air-tight connection, .[.and.]. disposable tip removing means for removing a disposable tip from said permanent tip member, said permanent tip member and said disposable tip removing means being supported so as to enable relative movement therebetween as a result of which a disposable tip is disconnected from said permanent tip member.Iadd., resilient means for biasing said permanent tip member and said disposable tip removing means away from each other, and actuating means integrally connected with but spaced from said permanent tip member, and wherein said disposable tip removing means is a sleeve-like unit that encloses said permanent tip member but leaves the end thereof projecting from the sleeve-like unit, and wherein said disposable tip removing means is biased into abutting relationship with said actuating means by said resilient means. .Iaddend. .[.10. A pipette according to claim 9 wherein the disposable tip is a hollow conical element and said permanent tip member is adapted to fit within the disposable tip which is frictionally held thereon, and wherein the relative movement between said permanent tip member and said disposable tip removing means causes the latter to bear against the end of the disposable tip and thereby to push it off said permanent tip member..]. 
     
     
        .[.1.  A pipette according to claim 10 including resilient means for biasing the end of said permanent tip member on which a disposable tip is held and the bearing end of said disposable tip removing means away from each other..]. .[.12. A pipette according to claim 11 including a grip member means integrally connected with but spaced from said permanent tip member, and wherein said disposable tip removing means is a sleeve-like unit that encloses said permanent tip member but leaves the end thereof projecting from the sleeve-like unit, and wherein said disposable tip removing member is biased into abutting relationship with said grip member means by said resilient means..]. .[.13. A pipette according to claim 10 including means to effect relative movement between said permanent tip member and said disposable tip removing means whereby a disposable tip is 
     
     
        removed from said permanent tip member..]. 14. A manual pipette comprising, a permanent tip member adapted to have a disposable tip coupled thereto in an air-tight relationship, means for drawing a liquid into and for expelling it from a disposable tip coupled to said permanent tip member, means independent of said last named means disposed adjacent said permanent tip member and in spaced relationship from the end thereof to which a disposable tip is coupled for dislodging a disposable tip from said permanent tip member when a relative movement between said permanent tip member and said dislodging means is effected.Iadd., spring means for biasing said permanent tip member and said disposable tip dislodging means to said spaced relationship, and means adjacent the end of said pipette remote from said permanent tip member for applying a force to overcome the force exerted by said spring means and thereby effect a relative movement between said permanent tip member and said disposable tip dislodging means. .Iaddend. .[.15. A manual pipette according to claim 14 including spring means for biasing said permanent tip member and said disposable tip dislodging means to said spaced relationship..]. .[.16. A manual pipette according to claim 15 including means for applying a force to overcome the force exerted by said spring means and thereby effect a relative movement between said permanent tip member and said disposable tip dislodging 
     
     
        means..]. .[.17.  A manual pipette comprising a permanent tip member adapted to have a disposable tip frictionally connected to the outside surface of said member, a tip removing member adjacent the outside surface of said permanent tip member, and means supporting said members for relative movement therebetween whereby as a result of such movement a disposable tip is engaged by said tip removing member and freed from its frictional connection with said permanent tip member..]. .Iadd.18. A pipette adapted to have a disposable tip mounted at one end thereof, said pipette comprising a permanent tip member to which a disposable tip is frictionally joined so as to form an air-tight connection, and disposable tip removing means for removing a disposable tip from said permanent tip member, said permanent tip member and said disposable tip removing means being supported so as to enable relative movement therebetween as a result of which a disposable tip is disconnected from said said permanent tip member, resilient means for biasing said permanent tip member and said disposable tip removing means away from each other, and means adjacent the end of said pipette remote from said permanent tip member to effect relative movement between said permanent tip member and said disposable tip removing means whereby a disposable tip is removed from said permanent tip member without the need for a pipette operator to change his grip on the pipette when going from a pipetting to a detipping operation. 
     
     
        .Iaddend. .Iadd.19.  A manual pipette according to claim 5 wherein said sleeve member encompasses said elongated tubular member and is the member by which the pipette is gripped during pipetting and detipping operations whereby the plunger assembly is urged by its biasing means in one direction relative to said sleeve member and said finger grip member is urged by said biasing spring means in the opposite direction relative to said sleeve member so that said plunger assembly is manually actuated in one direction during a pipetting operation and the finger grip member is manually actuated in the opposite direction during a detipping operation. 
     
     
        .Iaddend. .Iadd.20.  A pipette comprising, pipette means having a distal end and a proximate end with a central bore extending longitudinally through said means and adapted to have a disposable pipette tip wedge fitted on the outside surface at the distal end of said means, piston means connected to said pipette means including a piston actuating member extending axially from the proximate end of said pipette means, spring means biasing said piston means to its most remote position from the distal end of said pipette means, a disposable tip removing member slideably positioned at the distal end of said pipette means, additional spring means for biasing said tip removing member away from the end of said pipette means so that a disposable tip may be fitted on the distal end of said pipette means, and means located at the proximate end of said pipette means to enable the application of a manual force to overcome the force exerted by said additional spring means and cause a relative movement between said pipette means and said tip removing member, whereby said tip removing member engages a disposable tip fitted on said pipette means and pushes the disposable tip off said pipette means. .Iaddend. .Iadd.21. A pipette according to claim 20 wherein said tip removing member is a sleeve means that substantially encloses said pipette means and is the principal means by which the pipette is grasped, said force applying means is connected to said pipette means, and said additional spring means biases said sleeve member into engagement with said force applying means. 
     
     
        .Iaddend. .Iadd.22.  A pipette according to claim 21 wherein said sleeve means is provided with an internal abutment means, said pipette means is provided with a spring retaining means, and said additional spring means is a compression spring acting between said abutment means and said spring retaining means..Iaddend.