EP0992288A2 - Pipette tip ejection arrangement - Google Patents

Abstract

Pipetting system with a pipetting device and at least one pipette tip detachably fastened to it, at least one fastening element on the pipetting device to which the pipette tip is fastened, a discharge device on the pipetting device, which has an axially movable dropping element for releasing the pipette tip from the fastening element during an axial movement of the dropping element and one Has drive device for driving the axial movement of the ejection element, and an essentially axial drive movement of the drive device into an axial movement of the ejection element transmitting means gear, pressure medium gear or articulated gear with which the ejection rod at least when loosening the pipette tip from the fastener over a smaller path is axially movable as the essentially axial drive movement and a dropping force on the pipettes which exceeds the force for the substantially axial drive movement is practicable. <IMAGE>

Description

The invention relates to a pipetting system with a pipetting device and at least one pipette tip releasably attached thereto.

Such pipetting systems are used primarily in the laboratory for dosing liquid quantities used. These are sucked into and out of pipette tips pushed out. For this purpose, pistons are usually slidably arranged in a cylinder. In air cushion systems, the piston and cylinder are in the pipetting device integrates and communicates with the pipette tip so that the dosage of the liquid is mediated by an air cushion. In direct displacement systems are pistons and cylinder integrated into the tip and act directly on the liquid that is sucked in on. Such pipette tips are also referred to as syringes. Pistonless Systems can in particular have a pipette tip with a balloon-like end section have, which expands for sucking in liquid and for expelling is compressed.

The pipette tip is releasably connected to the pipetting device so that it can be exchanged for a fresh pipette tip after use, whereby contamination can be avoided in subsequent doses. Disposable pipette tips are inexpensive plastic available.

The pipetting devices have a fastening attachment for fastening Pipette tips. This is usually a conical projection on which a pipette tip is clamped with a conical receptacle. This can be done without touching the Pipette tip by pushing the fastening attachment onto a pipette tip take place, which is available in a holder.

aufgerammten" Pipettenspitzen ist allerdings ein hoher Kraftaufwand für den Spitzenabwurf erforderlich, der bereits bei Einkanalsystemen die Benutzung beeinträchtigen oder unmöglich machen kann. Besonders hoher Kraftaufwand kann sich durch vervielfachte Spitzenabwurfkräfte bei Mehrkanal-Pipettiersystemen ergeben, die mehrere parallel abzuwerfende Pipettenspitzen haben.In order to avoid contamination of the operating personnel, it is also desirable to detach the pipette tip from the attachment attachment without touching it. For this purpose, pipetting devices are often equipped with a discharge device which is assigned to the upper edge region of the pipette tip with a discharge sleeve and can be actuated at a discharge button. With particularly firmly attached or even

rammed "pipette tips, however, require a high level of force for tip ejection, which can impair the use or make it impossible even in single-channel systems. Particularly high levels of force can result from multiplied tip ejection forces in multi-channel pipetting systems that have several pipette tips to be ejected in parallel.

A pipette with a tip remover is known from EP 0 566 039 B1 to facilitate use by reducing the dropping force Has lever mechanism. This lever mechanism jumps sideways from one Pipette housing in front and must be pressed manually. He can have a gear on that an actuating arm for the pipette tip rotatable in a vertical plane is articulated. Furthermore, the inner flank of the gear meshes with a rack the side of the elongated case. On the outside of the operating arm is on a hollow push rod is arranged on the side of the housing, which is threaded combs on the inside with the outside of the gear. If the push rod is pushed down, the gear moves down and takes at the same time the actuating arm and a discharge sleeve, creating a pipette tip is pushed off by a fastening cone. The push rod lays exactly twice the distance back as the operating arm and is that on the push rod The force exerted is half the force exerted to push off the pipette tip Force. This system is structurally complex and leaves only one Gear ratio of 1: 2 too, so that it is limited in applicability.

Proceeding from this, the invention is based on the object of having a pipetting system to create a dropping device that other than the aforementioned Translation ratios and constructive simplifications enabled.

The object is achieved by a pipetting system with the features of claim 1 solved. Advantageous embodiments of the pipetting system are in the subclaims specified.

• eine Pipettiervorrichtung und mindestens eine daran lösbar befestigbare Pipettenspitze,
• mindestens einen Befestigungselement an der Pipettiervorrichtung, an dem die Pipettenspitze befestigt ist,
• eine Abwurfeinrichtung an der Pipettiervorrichtung, die ein axial bewegliches Abwurfelement zum Lösen der Pipettenspitze vom Befestigungselement bei einer Axialbewegung des Abwurfelementes und eine Antriebseinrichtung zum Antreiben der Axialbewegung des Abwurfelementes hat, und
• ein eine im wesentlichen axiale Antriebsbewegung der Antriebseinrichtung in eine Axialbewegung des Abwurfelementes übertragendes Zugmittel-, Druckmittel- oder Gelenk-Getriebe, mit dem das Abwurfelement zumindest beim Lösen der Pipettenspitze vom Befestigungselement über einen geringeren Weg axial bewegbar ist als die im wesentlichen axiale Antriebsbewegung zurücklegt und eine die Kraft für die im wesentlichen axiale Antriebsbewegung übersteigende Abwurfkraft auf die Pipettenspitze ausübbar ist.

The pipetting system according to the invention has

• a pipetting device and at least one pipette tip releasably attachable thereto,
• at least one fastening element on the pipetting device to which the pipette tip is fastened,
• a discharge device on the pipetting device, which has an axially movable discharge element for releasing the pipette tip from the fastening element during an axial movement of the discharge element and a drive device for driving the axial movement of the discharge element, and
• an essentially axial drive movement of the drive device into an axial movement of the ejection element transmitting means, pressure medium or articulated gear, with which the ejection element is axially movable at least when the pipette tip is detached from the fastening element over a shorter distance than the essentially axial drive movement and a dropping force exceeding the force for the essentially axial drive movement can be exerted on the pipette tip.

The pipetting system according to the invention is an alternative to the known pipette with tip remover, due to the traction mechanism, pressure transmission or articulated gearbox both the known transmission ratio and others Ratios and thus increased freedom of design and expanded Possible applications. Are also in an inventive Pipetting system transmission ratios possible during a tip ejection vary. The pipetting system also opens up the possibility structural simplifications.

With a traction mechanism transmission design, the drive device and the Ejection element have overlapping end sections and the gearbox one at the end portion of the discharge element rotatably mounted guide roller and a Have rope that is fixed at one end with respect to the fastener and at the other end is fixed to the end section of the drive device. Prefers a drive rod and the ejection element are aligned parallel to each other. With the essentially axial drive movement over a certain one The ejection element only moves half of this way. It says however, a force is available on the ejection element for releasing the pipette tip, which is about twice as large as that applied for the drive movement Force. Other gear ratios can be achieved if more than one Deflection rollers are mounted on the discharge element. This gear enables structurally particularly simple solutions.

In the case of a pressure medium transmission design, the transmission has one with the drive device connected first piston which is displaceable in a first cylinder is and a second piston connected to the ejection element, which in a second cylinder is displaceable, the two cylinders communicating with one another, this communicating cylinder system is sealed off from the environment and is filled with hydraulic fluid and the first piston has a smaller cross-sectional area than the second piston.

In this hydraulic transmission system, the first piston over a certain distance a displacement of the second piston over a shorter distance, the ratio of the distances being inversely proportional to the ratio of the cross-sectional areas of the two pistons. However, that is exerted by the second piston on the ejection element and thus on the pipette tip Force greater than that exerted by the drive rod on the first piston Force, the ratio of these forces being proportional to the ratio of the cross-sectional areas of the two pistons.

In a further pressure medium transmission design, the transmission has one with the Drive device connected first bellows and one with the discharge element connected second bellows, the bellows communicating with each other are connected with this communicating bellows system Hydraulic fluid is filled and the first fold has a smaller cross section than the second bellows.

With this system, bellows of different diameters are used corresponding result as achieved with the pistons of different diameters. However, there is no sealing of the pistons or piston rods here.

In both types of pressure transmission, there is extensive freedom with the Choice of gear ratios. There are also very simple structural designs possible.

In the case of an articulated gearbox design, the gearbox has a first articulated rod on, which is articulated to the drive device and a second joint rod, the is articulated to the ejection element, the two joint rods at the other end are hinged together and in the articulation area along a with respect to the Fastener are fixed guide performed a first guide section has, the distance from a common axis of the drive movement and the discharge element in the direction from the drive device to Throwing element increases and which is arranged so that the articulation area movable along this first guide section when a pipette tip is released is.

If the drive rod is moved axially to eject a pipette tip, the articulation area of the two joint rods reaches the area of the first one Guide section, in which it is laterally from the common axis of the drive movement and evades the release element. On the one hand, the drive movement a larger path than the ejection element and on the other hand provided a greater force on the ejection element than on the Drive rod is exercised. This version also enables extensive Variability of the transmission ratio and even variable transmission ratios during a dropping process. Here too are very simple constructive designs possible.

In all versions, the discharge element can be a discharge rod. This can in turn with at least one further element of a discharge device be connected. The fastener can be a mounting approach, a Attachment receptacle or the like.

The invention can be used in all types of pipetting systems, in particular with piston stroke and direct displacement systems, with single stroke and Dispenser systems, for manual and stationary systems, for manual and motor-driven systems and one-hand and multi-channel systems.

Further details and advantages of the invention are set out in the following Description of four embodiments can be seen.

Fig. 1

Handpipettiersystem in grobschematischer Ansicht;

Fig. 2

Abwurfeinrichtung mit Zugmittel-Getriebe in einem Längsschnitt durch eine Pipettiervorrichtung;

Fig. 3

dieselbe Abwurfeinrichtung in einem um 90° gedrehten Längsschnitt durch die Pipettiervorrichtung;

Fig. 4

Abwurfeinrichtung mit Druckmittel-Kolbengetriebe in einem Längsschnitt;

Fig. 5

Abwurfeinrichtung mit Druckmittel-Faltenbalggetriebe im unbetätigten Zustand in einem Längsschnitt;

Fig. 6

dieselbe Abwurfeinrichtung in betätigtem Zustand im Längsschnitt;

Fig. 7

Abwurfeinrichtung mit Gelenk-Getriebe mit zwei Gelenkketten im Längsschnitt;

Fig. 8

Abwurfeinrichtung mit Gelenk-Getriebe mit nur einer Gelenkkette im Längsschnitt;

Fig. 9

dieselbe Abwurfeinrichtung in einem Schnitt entlang der Linie IX-IX der Fig. 8.

The invention is explained below with reference to the accompanying drawings of five exemplary embodiments. The drawings show:

Fig. 1

Manual pipetting system in a rough schematic view;

Fig. 2

Ejector with traction mechanism in a longitudinal section through a pipetting device;

Fig. 3

the same ejection device in a longitudinal section rotated through 90 ° through the pipetting device;

Fig. 4

Discharge device with pressure medium piston gear in a longitudinal section;

Fig. 5

Discharge device with pressure medium bellows gear in the unactuated state in a longitudinal section;

Fig. 6

the same ejection device in the actuated state in longitudinal section;

Fig. 7

Ejection device with articulated gear with two articulated chains in longitudinal section;

Fig. 8

Ejection device with articulated gear with only one articulated chain in longitudinal section;

Fig. 9

the same discharge device in a section along the line IX-IX of FIG. 8.

In the following description of various exemplary embodiments the same reference numbers are used for corresponding components. The associated The description is valid for all exemplary embodiments which have these reference numbers exhibit.

1, a hand-held pipetting system according to the invention has a hand-held pipetting device 1 with a housing 2 and a housing shaft 3, the bottom End has a mounting boss in the form of a plug-on cone 4.

A pipette tip 5 is placed on the plug-on cone 4 so that it clamps, however can be pushed off by the plug-on cone 4.

An actuation button 6 protrudes out of the housing 2 at the top. By pressing in axially the actuating button 6 can be in the housing 2 between two stops a piston can be moved in a cylinder. The cylinder is over a channel connected to an opening at the lower end of the plug-on cone 4. By shift an air column of the piston is moved in the channel. After pressing the Piston 6 can return to its starting position with spring support, the air column can suck liquid into the pipette tip 5. Again Pressing the actuating button 6 causes the liquid to be expelled from the Pipette tip 5.

For a subsequent detachment of the pipette tip 5 from the plug-on cone 4, the Pipetting device a discharge device 7. This has a sliding on the ejection sleeve 8 arranged on the housing shaft 3 with a lateral projection 9 at the top inside the housing 2. To actuate the ejector sleeve 8 one on a longitudinal side in the housing 2 parallel to the housing shaft 3 Drive rod 10, which can be actuated by means of a release button 11, which above the housing 2 protrudes. The lower end of the drive rod 10 is over a Gear 12 connected to the upper end of a discharge rod 13, which also is parallel to the housing shaft 3. The lower end of the ejector rod 13 is again assigned to the lateral projection 9 of the discharge sleeve 8.

The gear 12 is a traction, pressure or articulated gear. It has a Reduction. As a result, the displacement path is when the ejection device 7 is actuated the release button 11 larger than the displacement of the discharge sleeve 8, but exceeds that of the discharge sleeve 8 on the upper edge of the pipette tip 5 force exerted the force exerted on the release button 11. Stuck Pipette tips 5 can thus be detached from the pipetting device 1 more easily.

2 and 3 show an embodiment of the transmission as a traction mechanism transmission 12 '. Here there is a guide block 14 at the lower end portion of the drive rod 10, in which an axially directed guide groove 15 is formed, which has a lateral opening 16 has. The drive rod 10 adjoins the guide block 14 an axial guide bore 17.

The ejector rod 13 is guided through a transverse housing wall 18. The Ejector rod 13 carries a ring 19 below the housing wall 18, which it against pulling up ensures. A compression spring is located above the housing wall 18 21 guided on the discharge rod 13, which is at one end on the housing wall 18 and at the other end is supported on a further ring 21, which is on the discharge rod 13 sits.

At an upper end section, the ejector rod 13 carries a bearing block 22 is pushed onto the discharge rod 13 and by means of rings 23, 24 on the discharge rod 13 secured. The discharge rod 13 projects with its upper end into the Guide bore 17 into it and the bearing block 22 is in the guide groove 15 of the Guide block 14 out. Above the bearing block 22 is on the Ejection rod 13 is guided by a compression spring 25, which ends at the ring 24 and at the other end at a step 26 between the guide groove 15 and the guide bore 17 supports.

On a bearing pin 27 of the bearing block 22 protruding from the opening 16 a deflection roller 28 is mounted. The deflection roller 28 has a groove 29 on the circumference. A rope 30 is laid around the deflection roller 28 and guided in the groove 29. The rope 30 can in particular be a steel or wire rope. It runs about halfway through of the circumference of the deflection roller 28. At one end it is below the bearing block 22 in the housing 2 and thus with respect to a plug-on cone 4 for a pipette tip 5 fixed. At the other end, it is below the deflection roller 28 at 32 on the guide block 14 set.

The attachment to the housing 2 takes place, for example, by means of a loop that opens a cone sits. The attachment to the guide block 14 takes place, for example by means of a rope-proof ball or another thickening, which from the side in a receptacle is pushed, which has a passage for the rope 30.

The bearing block 22 has a ring 33 concentric with the bearing journal 27, which secures the deflection roller 28 with a bead 34 on the inner circumference and the rope 30 prevents slipping out of the groove 29. The wreath 33, however, has Through bores through which the ends of the rope 30 are guided to the outside are.

When the release button 11 is not actuated, the gear 12 'takes the arrangement shown on. If the release button 11 is actuated, the drive rod 10 pulls with the Guide block 14 the attached end of the rope 30 down. Doing so the rope 30 over the pulley 28 and at the same time the pulley 28 and thus the bearing block 22 and the ejector rod 13 are pulled down. This traction mechanism 12 'causes the ejector rod 13 to move an ejection distance which is only half as large as the displacement distance of the drive rod 10. On the other hand the ejection force that can be exerted by the ejection rod 13 is twice as large as the force applied to the release button 11. The lower end of the drop bar 13 can therefore directly or via a discharge sleeve 8 an increased force on a pipette tip 5 exercise.

After releasing the release button 11, the spring 20 presses the traction mechanism gear 12 'back to the drawn starting position. The spring 25 pushes the drive rod 10 with respect to the ejection rod 13 in the starting position and is the same thus the differences in the displacements of drive rod 10 and Throwing rod 13 so that the rope 30 is kept under tension.

By attaching two deflection rollers to the discharge rod and one fixed to the housing stored pulley and a cable guide from the drive rod over the first deflection roller of the discharge rod to the housing-fixed deflection roller and from there to the second deflection roller of the ejector rod and from there to a housing-fixed one Determination can even reach a quarter of the effort. Further Variations are possible through roller arrangements and rope guides, as in the case of Pulley blocks are known.

The pressure medium piston transmission 12 ″ shown in FIG. 4 can also be in one Pipetting system according to FIG. 1 are used. In this case the drive rod is 10 connected to a first piston 33. This is axially displaceable in arranged in a cylinder 34. The drive rod 10, which is also the drive rod of the piston 33 is sealed by the upper opening of the cylinder 34 guided. For this purpose, an O-ring 35 is supported on an inner shoulder of the cylinder 34 and pressed between the cylinder 34 and the ejector rod 10 by means of a screw ring 36, similar to a stuffing box seal.

The maximum diameter D _{1 of} the piston 32 is significantly smaller than the inside diameter of the cylinder 34.

At the upper end of the ejector rod 13 there is a second piston 37 which is guided into the other end of the cylinder 34. At the end of this end of the cylinder 34 there is a further O-ring 38 which is pressed against the outer circumference of the piston 37 in a sealing manner by means of a union nut 39. The outer diameter D _{2 of} the piston 37 corresponds approximately to the inner diameter of the section of the cylinder 34 in which it is displaceable.

The spring guided on the discharge rod 13 is supported at one end on the transverse one Housing wall 18 and at the other end on a shoulder 40 on the underside of the piston 37.

The interior of the cylinder 34 delimited by the pistons 33, 37 is completely included Hydraulic fluid 41 filled.

The transmission 12 ″ is shown in an unactuated arrangement. For a tip ejection, the ejection button 11 is pressed so that the piston 33 dips deeper into the cylinder 34. As a result, hydraulic fluid is displaced and the piston 37 is moved downward against the action of the spring 20, so that the ejection rod 13 takes the ejection sleeve 8 with it and ultimately pushes the pipette tip 5 off the plug-on cone 4. The distance traveled by the drive rod 10 is less than the distance covered by the ejection rod 13 and the ejection force (F ₂ ) exerted by the ejection rod 13 on the ejection sleeve 8 is greater than the force acting on the ejection button 11 (F ₁ ), since the Diameter D _{2 of} the piston 37 exceeds the diameter D _{1 of} the piston 33. The following applies to the force transmission ratio ü (= F ₂ / F ₁ ) of this hydraulic transmission system: ü = D 2nd 2nd / D 1 2nd

With this gearbox design you are in the choice of the gear ratio ü very free.

Instead, a pipette system according to FIG. 1 can also be equipped with a pressure medium bellows gear 12 '' 'according to FIGS. 5 and 6. This has a first one Bellows 42, which is connected at the end to the drive rod 10, so that it from this can be compressed. It also has a second bellows 43 which is connected at the front to the ejector rod 13 so that it can be unfolded axially shifts. The two bellows 42, 43 connected to each other via a short hose section 44, so that their Communicate interiors with each other. In this area runs between the Bellows 42, 43 a radially directed groove 45 in which a transverse Housing wall 18 engages. This has a laterally open slot 46 for insertion of the hose section 44.

The bellows 42, 43 and the hose section 44 are filled with a hydraulic fluid 41 or another suitable fluid. They have a circular cross section, and the bellows 42 can have a diameter (D1) that is approximately half that of the bellows 43 (D ₂ ).

The bellows 42, 43 can be made from an elastic material, that they have the unconcerned endeavor to take the initial form shown in FIG to assume. However, it is also possible to use an additional form To achieve spring device.

Based on this, the bellows 42 can be compressed by moving the drive rod 10 in the direction of the arrow, the hydraulic fluid 41 being displaced into the bellows 43 and expanding it. Finally, the arrangement according to FIG. 6 is achieved in which the bellows 42 is maximally compressed and the bellows 43 is maximally expanded. The compression path Y of the bellows 42 is significantly greater than the expansion path Z of the bellows 43. On the other hand, the bellows 43 presses with a significantly greater ejection force (F ₂ ) on the ejection rod 13 than is introduced into the bellows 42 via the drive rod 10 (F ₁ ). With this hydraulic transmission system too, the transmission ratio ü (= F ₂ / F ₁ ) is given by: ü = D 2nd 2nd / D 1 2nd

The pipetting system according to FIG. 1 can advantageously also be equipped with an articulated gear 12 ^IV according to FIG. 7. The drive rod 10 and the ejector rod 13 are guided coaxially in axial guides 47, 48 of the housing. At the lower end of the drive rod 10, two first joint rods 50, 50 'are articulated at 49. At the upper end of the ejector rod 13, two second joint rods 52, 52 'are articulated at 51. In each case a first joint rod 50, 50 'and a second joint rod 52, 52' are hinged to one another at 53, 53 '. A roller 54, 54 'is rotatably supported there.

Between the axial guides 47, 48 in the range of motion of the rollers 54, 54 ' a guide on both sides of the axis of the drive rod 10 and the discharge rod 13 55, 55 'formed with a certain contour. This is removed in a first Guide portion 56, 56 'from the aforementioned axis and is in a second Guide section 57, 57 'parallel to this axis.

When the ejection device 12 ^{IV is} actuated by moving the drive rod 10 in the direction of the arrow, the rollers 54, 54 ′ can initially be located within the guide 47. As soon as the rollers 54, 54 'reach the area of the guide 55, 55', they follow the contour of the first guide section 56, 56 'and move away from one another. This situation is shown in Fig. 7. As a result, during the movement of the rollers 54, 54 'over the first guide section 56, 56', the ejector rod 13 is displaced a shorter distance than the drive rod 10. On the other hand, the ejector rod 13 can exert a greater force on an ejector sleeve 8 than on the drive rod 10 is exercised. Therefore, the pipette tip 5 is advantageously pressed off by the plug-on cone 4, while the rollers 54, 54 'are moved along the guide section 56, 56'. In the subsequent second guide section 57, 57 ', the movement of the ejection rod 13 in turn corresponds to the movement of the drive rod 10, as a result of which a pipette tip 5 can already be accelerated.

The first guide section 56, 56 'enables a force-intensifying transmission from Z. B. 3.5: 1 can be achieved. In the subsequent second management section 57, 57 'is the gear ratio 1: 1.

Subsequent to the first guide section 56, 56 ', in which the pipette tip is released, or instead can be used for the last swing "on one path-reinforcing "translation (eg 1: 2 or similar). Examples of such further guide sections 58, 58 'and 59, 59' are shown in broken lines.

Of course, other contours in the area of the guide 55, 55 'are also conceivable.

It is also interesting that despite the power boost when the pipette tip is ejected there is no need to shorten the overall stroke because the stroke is reduced during the discharge the ejection rod 13 can be made up at the end of the ejection process.

8 and 9, an articulated gear with a corresponding function can also can be realized by the drive rod 10 and the discharge rod 13 only are connected to one another via two joint rods 50, 52 and only on one side the common axis of movement of the drive rod 10 and the discharge rod 13 a guide 55 is formed with the different sections 56, 57 (or 58, 59) is. A wall 60 opposite the guide 55 can then have the limitations the guides 47, 48 are aligned. This is a more space-saving design possible.

It is understood that articulated gearbox according to FIGS. 7 to 9 with a spring device can interact, which on the ejector rod 13 against the direction of actuation act to reset them to a starting position.

Claims (26)

Pipetting system with a pipetting device (1) and at least one pipette tip (5) detachably attached thereto, at least one fastening element (4) on the pipetting device (1) to which the pipette tip (5) is fastened, a discharge device (7) on the pipetting device (1), which has an axially movable discharge element (13) for releasing the pipette tip (5) from the fastening element (4) during an axial movement of the discharge element (13) and a drive device (10, 11) for driving the axial movement of the discharge element (13), and an essentially axial drive movement of the drive device (10, 11) in an axial movement of the ejection element (13) transmitting traction means, pressure medium gear or articulated gear with which the ejection rod (13) at least when the pipette tip (5) is released from the fastening element (4) can be moved axially over a shorter distance than the essentially axial drive movement and an ejection force can be exerted on the pipette tip (5) which exceeds the force for the essentially axial drive movement. Pipetting system according to claim 1, wherein the ejection element (13) from one of the Axial movement when loosening the pipette tip (5) counteracting spring device (20) is applied. Pipetting system according to claim 2, wherein the spring device (20) a between an abutment that is fixed with respect to the fastening element (5) (18) and an abutment (21) of the ejector rod (13) is an effective compression spring. Pipetting system according to one of claims 1 to 3, wherein the drive device an axially movable drive rod (10) and / or a manually operable one Eject button (11). Pipetting system according to one of claims 1 to 4, wherein the drive device (10, 11) and the ejection element (13) overlapping end sections have and the gear (12 ') one at the end portion of the ejection element (13) rotatably mounted deflection roller (28) and a rope (30) which ends is fixed in position with respect to the fastening element (4) and at the other end to the End portion of the drive device (10) is fixed. The pipetting system of claim 5, wherein the end portions of the drive means (10, 11) and the ejection element (13) telescopic into each other are led. Pipetting system according to claim 5 or 6, wherein at the end portion of the discharge element (13) a bearing block (22) is fixed, on which the deflection roller (28) is rotatably mounted, the end portion of the drive device (10, 11) one Guide block (14) with a guide groove receiving the bearing block (22) (15) with a lateral opening (16) from which the deflection roller (28) protrudes. A pipetting system according to claim 7, wherein a protruding beyond the bearing block (22) End of the ejection element (13) in a on the guide groove (15) adjacent guide bore (17) of the end portion of the drive device (10, 11) is guided. Pipetting system according to one of claims 5 to 8, in which between the drive device (10, 11) and ejection element (13) a further spring device (25) is arranged, which counteracts the overlap of the end portions. Pipetting system according to one of Claims 7 to 9, in which the further spring device (25) one between the bearing block (22) and a step (26) between Guide groove (15) and guide bore (17) arranged compression spring (25). Pipetting system according to one of Claims 1 to 4, in which the gear (12 '') has a first piston (33) connected to the drive device (10, 11), which is displaceable in a cylinder (34), the gear (12 '') one with the Ejector element (13) connected to the second piston (37) in a cylinder (34) is displaceable, the two cylinders (34) communicating with one another, sealed this communicating cylinder system to the environment and is filled with hydraulic fluid (41) and the first piston (33) is a smaller one Cross-sectional area than the second piston (37). Pipetting system according to claim 11, wherein the two pistons (33, 37) in one single cylinder (34) are arranged. Pipetting system according to Claim 11 or 12, in which a drive rod (10, 13) of the first piston (33) and / or the second piston (37) in a sealing manner an insertion opening of the cylinder (34) is guided. Pipetting system according to one of Claims 1 to 4, in which the gear (12 '' ') a first bellows (42) connected to the drive device and the Gear (12 '' ') a second bellows connected to the ejection element (13) (43), which are communicatively connected to each other, whereby the communicating bellows system is filled with hydraulic fluid (41) and the first bellows (42) has a smaller cross section than the second bellows (43). The pipetting system according to claim 14, wherein the two bellows (42, 43) are connected to one another by a hose section (44). Pipetting system according to claim 15, in which between the bellows (42, 43) around the hose section (44) runs a radial groove (46) into which a housing wall engages with an opening (46) receiving the hose section (44). Pipetting system according to one of claims 1 to 4, ^wherein the gear (12 ^iv ) has a first articulated rod (50) which is articulated to the drive device (10, 11), the gear (12 ^iv ) has a second articulated rod (52) which is articulated on the ejection element (13), the two articulated rods (50, 52) being articulated at the other ends and being guided in the articulation area (53) along a guide (55) which has a first guide section (56), the distance of which a common axis of the drive movement and the ejection element (13) increases in the direction from the control device (10, 11) to the ejection element (13) and is arranged such that the articulation area (53) when loosening a pipette tip (5) along this first guide section (56) is movable. Pipetting system according to claim 17, in which in the articulation area (53) of the two Articulated rods (50, 52) a roller (54) is rotatably mounted on the guide (55) can be unrolled. The pipetting system of claim 17 or 18, wherein the guide (55) is adjacent a second guide section (57) to the first guide section (56) at a constant distance from the axis of the ejection element (13). Pipetting system according to one of Claims 17 to 19, in which the guide (55) adjacent to the first guide section (56) or the discharge section (57) has a further guide section (58, 59), the distance from the axis the ejection element (13) in the direction from the control device (10, 11) to Discharge element (13) decreases. Pipetting system according to one of claims 17 to 20, in which symmetrical to Axis of the ejection element (13) articulated rods (50, 52; 50 ', 52 ') and guides (55, 55') are arranged. Pipetting system according to one of claims 1 to 21, comprising a manual pipetting device (1) or has a stationary pipetting device. Pipetting system according to one of claims 1 to 22, which is a single-channel or Is multi-channel system. Pipetting system according to one of claims 1 to 23, which is a manual, electrical or otherwise driven ejector (9). A pipetting system according to claim 24, wherein the drive means a Drive rod (10) with a manually operated release button (11) or has a linear motor drive. Pipetting system according to one of claims 1 to 25, wherein the pipette tip (5) on the fastening element with a clamping force of at least 0.5 N, is preferably fastened from 0.5 to 80 N by the ejection device (7) can be overcome.

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