Measuring and testing – Sampler – sample handling – etc. – Capture device
Reexamination Certificate
1999-12-21
2002-12-31
Noland, Thomas P. (Department: 2856)
Measuring and testing
Sampler, sample handling, etc.
Capture device
C073S864140, C073S864160, C073S864170
Reexamination Certificate
active
06499363
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a tip for a pipette used for transferring a specified amount of liquid from one vessel into another vessel and a pipette with the tip.
BACKGROUND OF THE INVENTION
A pipette is generally used, for example, when a sample of liquid for an analysis is transferred from a vessel for sample picking into a vessel for an analysis. As a pipette of such kind, there is known one which has a small-diameter nozzle formed at a tip end of a body vessel and a suction chamber formed in a middle part of the body vessel.
The nozzle of the pipette is put in a liquid in the vessel for sample picking with the suction chamber compressed, and the suction chamber is then reduced in pressure so that the pipette sucks a liquid sample. Thereafter, the nozzle is inserted into the vessel for an analysis, and the suction chamber is then compressed again so that the pipette discharges the sucked liquid sample into the vessel for an analysis. In this manner, the liquid sample is transferred from the vessel for sample picking to the vessel for an analysis.
The above-mentioned convention pipette is a fixed-capacity type one in which the amount of a single suction of liquid sample is fixed. Therefore, its range of use is limited, which invites poor versatility. For example, when urinalysis is carried out in a physical checkup or the like, picked urine is first centrifuged, the supernatant fluid is then removed and 200 &mgr;l of liquid sample is prepared. Thereafter, 200 &mgr;l of liquid sample and the residue are mixed and from the mixture thus obtained, 15 &mgr;l of liquid sample for a urine precipitation test is picked up.
Thus, since the amount of suction of the conventional pipette is fixed, 200 &mgr;l sampling and 15 &mgr;l sampling cannot readily be set, resulting in expending much time and effort in carrying out urinalysis.
To cope with this, there is proposed a variable-capacity type pipette which is variable in sampling amount, as disclosed in Japanese Patent Application Laid-Open Gazette No. 8-332397. In this pipette, however, since a tip is simply fitted to a nozzle, this makes it difficult to determine whether or not the attachment of the tip to the nozzle has been fully completed.
In particular, the tip as mentioned above requires detachment and replacement with a new one for each sampling. In addition, there is a strong demand for prompt analyses of a large number of samples. Therefore, the tip should be attached to the nozzle with ease and reliability and simultaneously should be detached therefrom with ease. Additionally, since it is necessary that the pipette ensures providing a constant sampling amount at any time, a reliable seal must be formed between the tip and the nozzle. As a result, two opposing requirements, i.e., ensured sealing property and ease of detachment, must be satisfied.
The present invention has been made in view of the foregoing problems and therefore has its object of making a tip readily detachable from a pipette and providing ensured sealing property between the tip and a nozzle of the pipette.
SUMMARY OF THE INVENTION
To attain the above object, a first solution of the present invention is directed to a tip freely attachable to and detachable from a nozzle of a pipette. And, the tip includes: a tapered tip body having an elongated cylindrical form; a nozzle-fitting part formed in a root portion of the tip body; an annular part formed along an inner periphery of the nozzle-fitting part to extend inwardly therefrom for close contact with an outer periphery of the nozzle; and a thick portion formed around an outer periphery of an end portion of the nozzle-fitting part to extend outwardly therefrom for abutment against a tip releasing member for detaching the tip body from the nozzle of the pipette.
In a second solution of the present invention, the nozzle of the pipette in the first solution includes a root portion, a tip attachment part formed smaller in diameter than the root portion and continuously therefrom through a shoulder, and an annular part formed around an outer periphery of the tip attachment part to extend outwardly therefrom. Further, the annular part of the tip body is formed to be closely contactable with the annular part of the nozzle and to reach a position where a feeling of fitting between the tip body and the nozzle is provided through the abutment of an end surface of the nozzle-fitting part of the tip body against the shoulder of the nozzle at the completion of fitting of the tip body onto the nozzle. In addition, the thick portion of the nozzle-fitting part of the tip body is formed larger in diameter than the root portion of the nozzle to be located outside the root portion of the nozzle for abutment against the tip releasing member freely movable in an axial direction of the nozzle.
In a third solution of the present invention, both the annular parts of the nozzle and the tip body in the second solution are each formed into a projection of half-round cross section, and the annular part of the tip body is formed to complete the fitting of the tip body onto the nozzle by snapping over the annular part of the nozzle.
A fourth solution of the present invention is directed to a pipette. The pipette includes: a cylindrical casing; a cylinder provided in the casing; a suction chamber formed in the cylinder; a nozzle which is continuously formed at an outward end of the cylinder to extend to the outside of the casing and has a suction passage in communication with the suction chamber; at least one piston which is provided in the casing and is reciprocatably inserted into the suction chamber to suck and discharge liquid; and a tip freely attachable to and detachable from the nozzle.
The nozzle includes a root portion, a tip attachment part formed smaller in diameter than the root portion and continuously from the root portion through a shoulder, an annular part formed around an outer periphery of the tip attachment part to extend outwardly therefrom, and a tip releasing member provided outside of the root portion and freely movable in an axial direction of the nozzle.
The tip includes a tapered tip body having an elongated cylindrical form, a nozzle-fitting part formed in a root portion of the tip body, an annular part which is formed along an inner periphery of the nozzle-fitting part to extend inwardly therefrom and closely contacts with the annular part of the nozzle, and a thick portion formed around an outer periphery of an end portion of the nozzle-fitting part to extend outwardly therefrom and having a larger diameter than that of the root portion of the nozzle to be abuttable against the tip releasing member.
A fifth solution of the present invention is directed to a pipette. The pipette includes a cylindrical casing; a cylinder formed at an inner tip end of the casing; a first suction chamber which is formed in the cylinder and is open on an inward end surface of the cylinder; a nozzle which is formed at an outward end of the cylinder to extend to the outside of the casing and has a suction passage in communication with the first suction chamber; and a first piston reciprocatably inserted into the first suction chamber.
Further, the pipette includes: a second suction chamber which is formed in the first piston and is open on both end surfaces of the first piston; a second piston reciprocatably inserted into the second suction chamber, the second piston including a small-diameter part insertable into the second suction chamber and a large-diameter part engageable with the first piston to push the first piston; a first resilient member which pushes the first piston in a direction of protruding from the cylinder; and a second resilient member which pushes the second piston in a direction of protruding from the first piston, the second resilient member having less resiliency than the first resilient member.
In addition, the pipette includes: an operating lever which is provided in the casing, comes into contact at an inward end thereof with a top surface of the second piston, and operates the first and
Hishinuma Eiji
Inagaki Isao
Morimoto Ichiro
Shigematsu Kiyoto
Shimada Isao
Nixon & Peabody LLP
Noland Thomas P.
Studebaker Donald R.
The Sailor Pen Co. Ltd.
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