Measuring and testing – Sampler – sample handling – etc. – Capture device
Patent
1992-12-30
1994-09-20
Shaver, Kevin P.
Measuring and testing
Sampler, sample handling, etc.
Capture device
222 43, 222309, B01L 302
Patent
active
053478789
DESCRIPTION:
BRIEF SUMMARY
The present invention concerns a procedure for locking the adjustment means of a pipette.
The invention furthermore concerns a pipette.
A pipette is understood to be a device for liquid handling, e.g. for sampling and/or liquid dispensing, based in the first place on use of a plunger. The device may be a single-passage or multiple passage device.
In some of the pipettes, the outer body of the pipette is divided in its longitudinal direction into sections which can be joined by screwing. One of the sections constitutes a graduated adjustment ring for adjusting the dispensing volume of the pipette. The drawback embarrassing this kind of pipettes is awkwardness and inaccuracy of adjustment, that is, the adjustment ring is easily displaced from its setting in connection with tightening. Furthermore, if the body sections have been screwed together with excessive, or inadequate, force, the quantities which the device dispenses may differ from the set dispensing volume. In addition, the above causes have a detrimental effect on the reproducibility of the liquid handling operations which are carried out.
Moreover, a pipette is known in the art of which the adjustment means has been constructed in conjunction with the body. The pipette can be adjusted by rotating the plunger stem, whereby the position relative to the stem of an adjustment sleeve, or equivalent, rotatable relative to the stem changes and the dispensing volume of the pipette is accordingly altered, e.g. when the adjustment sleeve abuts on a limit stop or equivalent. The drawback of this kind of pipette is the change of dispensing volume caused by even minor rotation of the plunger, i.e., when the plunger happens to rotate inadvertently e.g. when the pipette is in use, the dispensing volume is altered.
The object of the present invention is to eliminate the drawbacks mentioned, and to disclose a novel means for liquid handling in which adjustment of the adjustment means is easy to implement, and in which the adjustment means positively and accurately retains the position at which it has been set.
In particular, it is an object of the invention to disclose a novel procedure for locking the adjustment means of a pipette, and a pipette with which sampling and/or liquid dispensing can be carried out accurately and reproducibly.
Regarding the features which are characteristic of the invention, reference is made to the claims section.
The invention is based on the idea that the locking means comprises a notched circle or the like, and a locking member disposed to be locked in any desired notch of said circle, to prevent inadvertent rotation of the adjustment means, and which can when desired be removed from the notch to enable the adjustment means to be rotated, one of the two elements, the notched circle or the locking member, being arranged to rotate along with the adjustment means and the other being connected to the body, to be substantially non-rotatable.
The locking means of the invention, with adjustment means, may be placed in the cylinder volume belonging to the liquid handling device, in conjunction with the plunger, with any part thereof, such as the plunger stem, with the operating means, or in general with any component of the liquid handling means.
In an embodiment of the invention, the notched circle rotates along with the adjustment means and the locking member is non-rotatable relative to the body. In another embodiment of the invention, the notched circle is non-rotatable relative to the body, and the locking member rotates along with the adjustment means.
In an embodiment of the invention, the plunger stem is provided with threads, and the adjustment means comprises an adjustment ring provided with a mating thread, the plunger stem being arranged to rotate in this ring for adjustment of the position in axial direction of the adjustment body and the plunger stem, relative to each other, and a limit stop which has been arranged to delimit the plunger motion when said adjustment ring meets said limit stop. The locking member is in that case
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patent: 3343539 (1967-09-01), Moorhouse
patent: 4081111 (1978-03-01), Sandow
patent: 4096751 (1978-06-01), Withers et al.
patent: 4165646 (1979-08-01), Shapiro
patent: 4395921 (1983-08-01), Oppenlander
patent: 4554134 (1985-11-01), Tervamaki et al.
Biohit Oy
Shaver Kevin P.
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