GB2045641A

GB2045641A - Pipette

Info

Publication number: GB2045641A
Application number: GB8007300A
Authority: GB
Original assignee: KOMMANDIITTIYHTIO FINNPIPETTE OSMO A SUOVANIEMI
Current assignee: KOMMANDIITTIYHTIO FINNPIPETTE OSMO A SUOVANIEMI
Priority date: 1979-03-23
Filing date: 1980-03-04
Publication date: 1980-11-05
Also published as: BR8001743A; FR2452089B1; SU915782A3; FI790990A; FI60137C; FI60137B; FR2452089A1; DE3008346C2; DE3008346A1; JPS6366575B2; GB2045641B; JPS55129159A

Abstract

A pipette provided with plunger(s) for filling with liquid has the plunger-operating piston rod (2) indirectly operated by a press knob shaft (9), parallel thereto and placed at a distance therefrom. Their surfaces facing each other are shaped into rack bar portions (10, 11), between which is fitted a cogwheel (12) jointly operative with them so that, when the press knob (8) is depressed the piston rod (2) is raised thus raising the piston(s) (4) in each cylinder portion (3) so as to suck liquid into the tip vessel (7) connected to each cylinder portion. <IMAGE>

Description

SPECIFICATION Pipette The subject of the present invention is a pipette comprising a handle portion, whose upper end is provided with a press knob with shaft and inside which a piston rod is fitted and that to the bottom end of the piston rod is connected a piston or, by the intermediate of a common actuating means of the pistons, several pistons and, for each piston, a cylinder part, which is fastened to the frame construction of the handle portion.

The object of the present invention is to provide a mechanically operative, simple pipette that is controlled by means of two pressknobs, that operates by the hold of one hand, and whose construction principle is applicable both to single-channei and to multichannel pipettes. It is an object of the present invention to provide, e.g., a multi-dose pipette by means of which it is possible to take a portion of liquid into the disposable tip vessel and thereupon to distribute that portion as smaller doses of mutually equal magnitude one does after the other from the tip vessel.

The pipette in accordance with the present invention is mainly characterized in that the piston rod and the press knob shaft, which are parallel to each other, are placed at a distance from each other and their surfaces facing each other are shaped into rack bar portions, between which is fitted a cogwheel jointly operative with them so that, when the press knob is depressed, by the intermediate of the rack bar portion on the press knob shaft, of the cogwheel, of the rack bar portion on the piston rod, and of the piston rod, the piston or the pistons in each cylinder portion can be shifted from the lower position into the upper position so as to suck liquid into the tip vessel connected to each cylinder portion.

The invention comes out more closely from the following description and from the attached drawing, wherein Figure 1 shows the pipette in accordance with the invention as a multi-channel embodiment as a side view and in section and Figure 2 is an enlarged view of the dosage mechanism portion of the pipette with the dosage press knob being depressed.

Fig. 1 shows a four-channel pipette, which comprises a handle portion 1 and a frame casing 19, which are connected together by means of a threaded joint 20. To the disk 21 at the bottom part of the casing portion 1 9 are, side by side, attached the cylinder portions 3, whose outside faces become at the lower ends narrower conically downwards for the purpose of tight connecting of the tip vessels 7 of the disposable tip vessel element 6 to the cylinder portions 3. O-ring seals 21 are fitted into the grooves at the upper ends of the cylinder portions 3 between the piston 4 and the cylinder. The pistons 4 are at their upper ends connected to their common actuating means 5 of the pistons. A piston rod 2 projects from the actuating means 5 of the pistons into the handle portion 1.As is shown in Fig. 1, the handle portion 1 is also provided with a press knob 8 with shaft 9 so that the piston rod 2 and the press knob 8 shaft 9, which are parallel to each other, are placed at a distance from each other. The upper part of the piston rod 2 and the press knob 8 shaft 9 have, for example, a square cross-sectional form. The surfaces of the piston rod 2 and of the press knob 8 shaft 9 facing each other are shaped into rack bar portions 10 and 11, between which a cogwheel 1 2 fastened to the handle portion 1 and jointly operative with said rack bar portions is fitted. On the side of the piston rod 2 opposite to the rack bar portion 11, a diagonal upwardly directed toothing 1 3 is fitted onto the piston rod 2.

At the upper end of the handle portion 1, alongside the press knob 8, another press knob, a so-called dosage press knob 14, with a shaft 15, is fitted. A spring means 1 6 presses the dosage press knob to the upper position. In accordance with Fig. 1, a means, such as a catch or tongue 17, jointly operative with the diagonal toothing 1 3 on the piston rod 2, projects downwards from the lower part of the shaft 1 5 of the dosage press knob 14.The length of the shaft 1 5 of the dosage press knob 1 4 is such that the distance of movement of the dosage press knob 14 is larger than a distance between the teeth on the ratchet portion but smaller than two distances between the teeth on the ratchet portion 1 3. The unit 1 7 jointly operative with the slanting toothing on the piston rod 2 is designed so that it is by means of an obstacle 1 8 kept apart from the slanting toothing 1 3 when the dosage press knob 1 4 is in its upper position (Fig. 1).

The pipette in accordance with Fig. 1 operates as follows.

When the press knob 8 is depressed, the press knob shaft 9 moves downwards and then the rack bar portion 10 on the shaft 9 rotates the cogwheel 1 2. The cogwheel 1 2 in its turn transfers the movement to the rack bar portion 11, whereby the piston rod 2 rises. In Fig. 1 the press knob 8 is in the depressed position and the piston rod 2 in the upper position. When the piston rod 2 rises, it moves along with it, by the intermediate of the actuating means 5 of the pistons, correspondingly, the pistons 4, whereby a suction is produced into the cyinder portions 3 and liquid can then be sucked into the tip vessel 7 if their tips have been submerged into a basin containing liquid.When the dosage press knob 1 4 is hereinafter depressed, its movement is, by the intermediate of the shaft 1 5, transferred to the tongue 1 7. The lower tip of the tongue 1 7 is pressed against the diagonal toothing 13 at the upper end of the piston shaft 2 and the ratchet portion 1 3 moves a step downwards and, at the same time, pushes the pistons 4 and a quantity of liquid corresponding the shifting, off the tip vessels.

When the dosage press knob 14 is no longer depressed, the spring 1 6 raises it to the upper position (Fig. 1), whereby the obstacle 1 8 detaches the tongue 1 7 from the ratchet portion 1 3 with slanting toothing. When depressions of the dosage knob 14 are repeated, new stepwise movements are produced on the rack bar portions 10 and 11 as well as on the pistons 4 until they reach the limiters of their movement and the tip vessels have been emptied. Then the tip vessels 7 can be refilled by means of the press knob 8.

Claims

1. A pipette comprising a handle portion (1), whose upper end is provided with a press knob (8) with shaft (9) and inside which a piston rod (2) is fitted and that to the bottom end of the piston rod (2) is connected a piston or, by the intermediate of a common actuating means (5) of the pistons, several pistons (4) and, for each piston (4), a cylinder part (3), which is fastened to the frame construction of the handle portion (1), characterized in that the piston rod (2) and the press knob (8) shaft (9), which are parallel to each other, are placed at a distance from each other and their surfaces facing each other are shaped into rack bar portions (10, 11), between which is fitted a cogwheel (12) jointly operative with them so that, when the press knob (8) is depressed, by the intermediate of the rack bar portion (10) on the press knob (8) shaft (9), of the coghweel (12), of the rack bar portion (11) on the piston rod (2), and of the piston rod (2), the piston or the pistons (4) in each cylinder portion (3) can be shifted from the lower position into the upper position so as to suck liquid into the tip vessel (7) connected to each cylinder portion (3).

2. A pipette as claimed in claim 1, characterized in that the upper end of the piston rod (2) projects from the handle portion (1) and is provided with a press knob so as to shift the piston or the pistons (4) from their upper position to their lower position in order to remove liquid from the tip vessel (7) connected to each cylinder portion (3).

3. A pipette as claimed in claim 1, characterized in that the piston rod (2) is provided with a second ratchet portion (13) that has diagonal upwardly directed toothing and that at the upper end of the handle portion (1) is fitted a dosage press knob (14) with shaft (1 5), which is by a spring means ( 1 6) pressed to the upper position and to which is connected a unit, such as a catch or tongue (17), jointly operative with the diagonal toothing (13) on the piston rod (2), and that the distance of movement of the dosage press knob (14) is larger than the distance between teeth on the ratchet portion (13) but smaller than two distances between teeth on the ratchet portion (13), whereby, when the dosage press knob (14) is depressed repeatedly, the piston rod (2t can be shifted downwards one distance between the teeth in the diagonal toothing of its ratchet portion (13) at a time while the said distance between teeth determines the magnitude of the dose to be removed from the tip vessel or tip vessels (7) at a time.

4. A pipette as claimed in claim 3, characterized in that the unit (17) jointly operative with the diagonal toothing on the piston rod (2) is designed so that it is by means of an obstacle (18) kept apart from the slanting toothing (1 3) while the dosage press knob (14) is in its upper position.

5. A pipette as claimed in claims 1 and 2, characterized in that the length of the distance of movement of the press knob (8) is, in a way in itself known, arranged so that it is adjustable.