Pipette with adjustable pipetting volume and locking system

Abstract

The invention relates to a pipette with a body for receiving a displacement device, the displacement device comprising a displacement chamber and a movable boundary element for bounding a pipetting stroke of the pipette. The pipette furthermore has an operating element for setting the pipetting volume of the pipette by movement of the boundary element in the body and for performing a pipetting operation, the operating element being in operative connection with a piston movable in the displacement chamber of the displacement device. The pipette furthermore comprises a counter for displaying the set pipetting volume and a locking mechanism for locking and/or unlocking volume setting by the operating element. It is provided that, on actuation of the operating element, the operating element is configured to perform a pipetting operation, to transfer the locking mechanism into a locked position and to lock adjustment of the pipetting volume.

Claims

1. A pipette (10) comprising: a body (20) for receiving a displacement device (22), the displacement device (22) comprising a displacement chamber (24) and a movable boundary element (26) for bounding a pipetting stroke of the pipette (10), an operating element (12) is configure to set the pipetting volume of the pipette (10) by movement of the boundary element (26) in the body (20) and the operating element is configured to perform a pipetting operation, a piston (28) connected to the operating element (12) and configured to be moved in the displacement chamber (24) of the displacement device (22), a counter (30) for displaying the set pipetting volume, a coupling element (32) having gear teeth (36), a lifting rod, wherein the coupling element is coupled to the lifting rod (21) and the operating element (21), a locking mechanism (40) for locking and/or unlocking volume setting comprising; a locking element (41), wherein the volume setting is determined by the operating element (12) by rotating the operating element (12) upon which the boundary element (26) is moved, a connecting element (46) which connects the locking element (41) with the coupling element (32) which connects the counter (30) with a setting mechanism (34) for moving the boundary element (26) in the displacement chamber (24), wherein, upon actuation of the operating element (12), the operating element (12) is configured to perform a pipetting operation, to transfer the locking mechanism (40) into a locked position and to lock adjustment of the pipetting volume by axial displacement of the operating element (12) which pushes the locking element (41) in the axial direction into the coupling element (32), gear teeth (48) are formed on the locking element (41) which on the axial displacement of the locking element (41) engage in gear teeth (36) of the coupling element (32) and locks rotation of the operating element (12) and displacement of the boundary element (26) of the displacement chamber (24), wherein an unlocked switching position of the locking mechanism (40), the coupling element (32) transmits a rotational movement of the operating element (12) configured to adjust the pipetting volume to the counter (30).

2. The pipette (10) according to claim 1, wherein characterized in that the locking element (41) is axially displaced on performance of a pipetting operation in a direction opposed to the unlocking direction and thereby locks volume adjustment of the pipette (10).

3. The pipette (10) according to claim 1, wherein characterized in that the pipette (10) comprises a rotary element (50) and the locking element (41), the rotary element (50) being in operative connection with the locking element (41) such that the rotary element (50) rotates into a travel path of the operating element (12) when the locking element (41) is brought into an unlocked position.

4. The pipette (10) according to claim 3, wherein the rotary element (50) and the locking element (41) are connected to one another via a slotted link mechanism (52).

5. The pipette (10) according to claim 3, wherein the rotary element (50) is fastened to the body (20) of the pipette (10) by way of a shield (54).

6. The pipette (10) according to claim 1, wherein characterized in that the locking element (41) is arranged in a recess (60) of the body (20).

7. The pipette (10) according to claim 1, wherein a finger hook (62) is arranged on the body (20), the locking mechanism (40) being arranged on a side of the body (20) opposite the finger hook (62).

8. The pipette (10) according to claim 1, wherein a locking element (41) has a frame (74) and an elastic tongue (68) formed on the frame (74), wherein, on the elastic tongue (68), a hook (70) is provided which projects radially inward beyond the elastic tongue (68).

9. The pipette (10) according to claim 8, wherein a latching tab (64) is provided on the locking element (41), which latching tab is configured to engage in a recess (66) on the body (20) of the pipette (10) or in a recess (66) on a shield (54) inserted into the body (20), such that the locking element (41) is held in an unlocked position of the locking mechanism (40) in which volume setting of the pipette (10) is possible.

10. The pipette (10) according to claim 8, wherein a locking slide (42) is arranged on the pipette (10), the locking slide (42) bringing about on actuation an axial displacement of the locking element (41) along a longitudinal axis of the pipette (10).

Description

(1) The invention is explained below in exemplary embodiments with reference to the accompanying drawings. Identical components or components with the same function are denoted with the same reference numerals in the various figures. In the drawings:

(2) FIG. 1 shows a sectional representation of a pipette according to the invention with an adjustable pipetting volume and locking system for temporary and reversibly releasable locking volume setting of the pipette;

(3) FIG. 2 shows a three-dimensional schematic representation of the operating element and locking system of a pipette according to the invention;

(4) FIG. 3 shows a simplified representation of an upper part of a pipette according to the invention;

(5) FIG. 4 shows an upper part of a pipette according to the invention in a three-dimensional representation;

(6) FIG. 5 shows a sectional representation through a locking mechanism in an upper part of a pipette according to the invention.

(7) FIG. 6 shows an alternative embodiment of an operating element and of a locking system of a pipette according to the invention;

(8) FIG. 7 shows a locking element of a locking system of a pipette according to the invention; and

(9) FIG. 8 shows a shield of a locking system of a pipette according to the invention in operative connection with the locking element.

(10) FIG. 1 shows a sectional representation of a pipette 10 according to the invention. The pipette 10 has a pipette upper part 16 and lower part 17 couplable to the pipette upper part 16. The pipette upper part 16 comprises a body 20, there being an operating element 12, preferably a round operating button 14, emerging through an opening in the body 20 on an end face of the body 20 remote from the pipette lower part 17. The operating element 12 has three functions. The operating element 12 firstly serves to set a pipetting volume as the volume of liquid which, during a pipetting operation, is to be drawn up by the pipette 10 and then delivered back out. The pipetting volume is set by rotating the operating element 12, the set pipetting volume being increased by rotation of the operating element 12 in a first direction of rotation and decreased by rotation in a direction of rotation opposed to the first direction of rotation. Depending on the design, the settable pipetting volume is between a minimum pipetting volume and a maximum pipetting volume. The operating element 12 secondly serves to draw up and subsequently deliver liquid during a pipetting operation, an operating button 14 of the operating element 12 being displaced in the axial direction along a center axis of the pipette. The operating element 12 thirdly serves to eject the used pipette tip from a receptacle on the pipette lower part 17 after a pipetting operation. All three functions are preferably combined in the operating button 14 such that operation can proceed simply and conveniently with just a single operating button 14. Alternatively, the function can also be divided among a number of components of the operating element 12 and in particular an additional button for ejecting a used pipette tip can be provided next to the operating button 14. It is furthermore possible for the operating element 12 to have an operating button 14 for drawing up and delivering the liquid and an element displaced by the operating button 14 for setting the pipetting volume.

(11) The pipette 10 comprises a body 20 for receiving a displacement device 22, the displacement device 22 comprising a displacement chamber 24 and a movable boundary element 26 for bounding the pipetting stroke. The operating element 12 is configured for setting a pipetting volume of the pipette 10 by movement of the boundary element 26 in the body 20 and for performing a pipetting operation. The operating element 12 is in operative connection via a lifting rod 21 with a piston 28 movable in the displacement chamber 24 of the displacement device 22. The pipette 10 furthermore comprises a counter 30 for displaying the set pipetting volume and a locking mechanism 40 for locking and/or unlocking volume setting by the operating element 12. It is provided that, on actuation of the operating element 12, the operating element 12 is configured to perform a pipetting operation, to transfer the locking mechanism 40 into a locked position and to lock adjustment of the pipetting volume. A restoring spring 18 for the operating element 12 is furthermore provided in order to return the operating element 12 to the initial position once it has been relieved of load.

(12) The locking mechanism 40 comprises a locking element 41 and a locking slide 42 for unlocking the locking mechanism. The locking mechanism 40 furthermore comprises a latching element 44 with which the locking slide and/or the locking element 41 can be temporarily fixed in an unlocked switch position in order to enable simple setting of pipetting volume by rotation of the operating element 12.

(13) A transparent display window 31 is set into the body 20 to provide a view of the counter 30 from the outside and allow the set pipetting volume to be read. A movable boundary element 26 for the lifting rod 21 is provided in the body 20, a shoulder on the lifting rod 21 resting against the movable boundary element 26 and thereby limiting the stroke of the piston 28. Pipetting volume is set by moving the boundary element 26.

(14) The pipette lower part 17 comprises a displacement chamber 24, into which the piston 28 actuatable via the operating element 12 and connected to the lifting rod 21 extends. The pipette lower part 17 has a clamping zone 19 for receiving a pipette tip, wherein it is possible to detach the pipette tip from the clamping region 19 and thereby eject it by actuation of the operating element 12 via the ejector rod 37.

(15) In order to change the pipetting volume of the pipette 10, the locking slide 42 of the locking mechanism 40 is first brought into an unlocked position. An unlocked position should be taken to mean a position of the locking mechanism in which rotation of the operating element 12 and an associated change of the pipetting volume are possible. Once the desired pipetting volume has been set, the operating element 12 is then actuated to perform a pipetting operation. Actuation of the operating element 12 should in this connection be taken to mean pressing the operating element 12 with an associated axial displacement of the operating element 12 along a longitudinal axis of the pipette 10. The longitudinal axis extends in the plane of the drawing from the top downward and leads from the operating element 12 through the pipette upper part 16 and the pipette lower part 17 down to a receiving opening at the end of the pipette lower part 17 remote from the upper part 16. On actuation, the path of the operating element 12 is divided in three actuation zones.

(16) A first actuation zone serves for drawing up and delivering a liquid with the pipette and is also denoted stroke H. Starting from an unloaded starting position, the operating element 12 is pressed in the axial direction along a travel path into the body 20 of the pipette 10 by for example 2 mm to 16 mm depending on the set pipetting volume.

(17) The first actuation zone is followed by a second actuation zone, also denoted overstroke, which in particular serves to blow out from the pipette 10 any residual liquid possibly still adhering to a pipette tip mounted on a receptacle on the body 20 of the pipette 10 after liquid delivery. This overstroke proceeds by an additional movement of the operating element 12 in the axial direction beyond the endpoint of the stroke H on drawing up liquid by for example a further 4 to 6 mm. In the overstroke zone, a tripping element of the locking mechanism 40 protrudes into the travel path of the operating element 12 such that the locking mechanism 40 is tripped and a form-fitting connection between the locking element 41 and the coupling element 32 is produced when the overstroke is activated by the operating element 12. Volume adjustment is thus locked from this point in time onward in the pipetting operation. Such a locking operation can either be performed before the liquid is drawn up in order to fix the set pipetting volume, or can be initiated during the pipetting operation, in particular when blowing liquid out after liquid delivery.

(18) If the operating element 12 is pressed further in the axial direction into the body 20, an ejector mechanism connected to the operating element 12 pushes the used pipette tip from a receptacle on the body 20 in a third actuation zone in order to eject the used pipette tip. It is provided to this end that a tripping element is formed at an end of an ejector rod 37 of the ejector mechanism facing the operating element 12, which tripping element projects into the travel path of the operating element 12 and initiates ejection of the pipette tip when the operating element 12 is pressed beyond the limit stop of the overstroke further into the body 20 of the pipette 10.

(19) The actuation zones are preferably delimited from one another by a limit stop and an associated change in operating force in order to provide the user with sensitive feedback regarding the action currently being performed.

(20) FIG. 2 is a schematic representation of the locking mechanism 40 of the pipette 10 for locking a set pipetting volume. The locking mechanism 40 comprises a locking element 41 which locks volume adjustment of the pipette 10 by the operating element 12, i.e. locks rotation of the operating button 14, in that the locking element 41 engages in form-fitting manner in the coupling element 32 and thus locks rotation. A slotted link mechanism 52, in which a rotary element 50 is guided, is formed on the locking element 41. The rotary element 50 is fixed to a pivot point 51 on a shield 54 which is inserted into the opening at the end face of the body 20 and guides the operating element 12.

(21) Alternatively to a rotary element 50 or in addition to a rotary element 50, a sliding element 58 may also be provided which is introduced into the displacement path of the operating element 12 and, on actuation of the operating element 12 in the context of a pipetting operation, i.e. by axial displacement of the operating element 12 by pressure on the operating button 14, is activated and pushes the locking element 41 in the axial direction into the coupling element 32 in order to form a form-fitting lock. A shoulder of the ejector rod 37 arranged at one end of the ejector rod 37 is furthermore located in the displacement path of the operating element 12 such that, once the operating element 12 has been displaced sufficiently far along the longitudinal axis of the pipette 10, a pipette tip received on the clamping zone 19 is ejected in known manner.

(22) FIG. 2 furthermore shows an axle securing means 33 for securing an axle of the rollers of the counter 30 and a volume setting sleeve 35 together with a gearwheel 38 with which a rotational movement of the operating button 14 is transferable to the mechanism for moving the boundary element 26 shown in FIG. 1.

(23) FIG. 3 and FIG. 4 show a pipette upper part 16 of a pipette 10 according to the invention. It may be seen that a shield 54 is inserted in an opening in the end face of the body 20 and the operating element 12 in the form of the operating button 14 is guided through this shield. The operating element is displaceable in the axial direction along the center axis of the pipette over a stroke H and is rotatable about the center axis for adjustment of the pipetting volume V. A recess 60, in which a locking slide 42 of the locking mechanism 40 is arranged, is formed on the body 20 or on the shield 54.

(24) A finger hook 62 is formed on the body 20 so that the user can hold the pipette 10 in one hand and operate it with this hand. When a hand is wrapped around the body 20, the finger hook 62 accordingly rests on the user's index or middle finger such the user can preferably use their thumb to selectively actuate the locking slide 42 or the operating button 14 in order either to set the pipetting volume or to perform a pipetting operation.

(25) FIG. 5 shows a three-dimensional representation of the locking mechanism 40 arranged in the body 20 of the pipette 10. The locking mechanism 40 comprises a locking element 41 which can enter into operative connection with the coupling element 32 for coupling 30. To this end, gear teeth 48 are formed on the locking element 41 which, on axial displacement of the locking element 41 in the context of a locking operation, engage in gear teeth 36 of the coupling element 32 and thus form a locking form-fitting connection. While the gear teeth 36 are formed right around the circumference of the coupling element 32 and there is a comparatively large spacing between the individual teeth, the gear teeth 48 are formed on only a small circumferential range on the locking element 41 in order to permit fine latching engagement in this circumferential range. Manufacture of the locking element 41 is additionally simplified if the gear teeth are formed over only a small circumferential range, whereby manufacturing costs can be reduced.

(26) As is apparent in FIG. 5, the lifting rod 21 preferably takes the form of a polygonal shaft, the coupling element 32 being pushed onto the lifting rod 21 and being form-fittingly connected therewith. Torque applied to the operating element 12 on volume adjustment can thus straightforwardly be transmitted to the coupling element 32. A polygonal shaft and an associated form-fitting connection between the lifting rod 21 and the components arranged on the lifting rod 21 additionally enable simple displacement of the movable boundary element 26 for setting the pipetting volume.

(27) FIG. 6 shows an alternative exemplary embodiment of a locking system for temporary and reversibly releasable locking of a volume setting of the pipette 10. The locking system comprises a locking mechanism 40 with a locking element 41 which locks volume adjustment of the pipette 10 by the operating element 12, i.e. blocks rotation of the operating button 14, by gear teeth 48 on the locking element 41 engaging in form-fitting manner in gear teeth of the coupling element 32 and so blocking rotation. The locking element 41 comprises a frame 74 and an elastic tongue 68 projecting inward from the frame 74, on the end of which tongue a hook 70 is formed. A latching tab 64 is furthermore formed on this elastic tongue 68 in order to latch the locking mechanism 40 in an unlocked position and so allow the pipetting volume to be set. The locking mechanism furthermore comprises a locking slide 42 with which the locking element 41 can be transferred from the locked state into an unlocked state by sliding the locking slide 42 toward the operating element 12, i.e. upward in the depiction of the drawing. Displacement of the locking slide 42 disengages the locking element 41 from the coupling element 32 such that the pipetting volume of the pipette 10 can be set. The latching tab 64 formed on the locking element 41 here latches into a recess 66 on the shield 54 of the pipette 10 such that the hook 70 is advanced into a travel path of the operating element 12. If a new pipetting operation is carried out, the hook 70 of the locking element 41 is displaced downward in the depiction of the drawing by the operating element 12 and the gear teeth 48 on the locking element 41 are brought into engagement with the gear teeth on the coupling element 32 such that volume adjustment of the pipette 10 is locked. The latching tab 64 is here displaced from the recess 66 on the shield 54 on a surface 72 of the shield 54 such that the tongue 68 is elastically deformed and the hook 70 is bent out of the travel path of the operating element 12. In this way, the operating element 12 can be freely actuated while volume adjustment of the pipette 10 is locked.

(28) FIG. 7 shows an individual part drawing of the locking element 41 from the locking system shown in FIG. 6. The locking element 41 comprises a frame and an elastic tongue 68 projecting inward from the frame 74, on the end of which tongue a hook 70 is formed. Gear teeth 48 are furthermore formed on a lower annular portion of the locking element 41 in order to provide a form-fitting connection between the locking element 41 and the coupling element 32. A latching tab 64 is furthermore formed on the tongue 68, which tab, in an unlocked position of the locking system, latches into a recess 66 in the shield 54. If the locking element 41 is displaced toward the operating element 12 by actuation of the locking slide 42, the gear teeth 48 on the lower annular portion of the locking element 41 are no longer in engagement with the locking teeth on the coupling element 32, whereby setting of the pipetting volume is enabled by displacement of the boundary element 26 for the lifting rod 21.

(29) FIG. 8 shows an individual part drawing of a shield 54 for the locking system of a pipette 10 shown in FIG. 6. It can be seen here that a surface 72 on the shield 54 and a recess 66 in the surface 72 are provided. If the latching tab 64 of the locking element 41 latches in the recess, the hook 70 on the locking element 41 protrudes into the travel path of the operating element 12 such that, on operation of the pipette 10, volume adjustment is transferred into the locked operating state.

LIST OF REFERENCE SIGNS

(30) 10 Pipette 12 Operating element 14 Operating button 16 Upper part 17 Lower part 18 Restoring spring 19 Clamping zone for pipette tip 20 Body 21 Lifting rod 22 Displacement device 24 Displacement chamber 26 Movable boundary element 28 Piston 30 Counter 31 Display window 32 Coupling element 33 Axle securing means 34 Setting mechanism 35 Volume setting sleeve 36 Gear teeth on coupling element 37 Ejector rod 38 Gearwheel 40 Locking mechanism 41 Locking element 42 Locking slide 44 Latching element 46 Connecting element 48 Gear teeth (on locking mechanism) 50 Rotary element 51 Pivot point 52 Slotted link mechanism 54 Shield 56 Return spring 58 Sliding element 60 Recess 62 Finger hook 64 Latching tab 66 Recess 68 Tongue 70 Hook 72 Surface on the shield 74 Frame H Stroke by axial movement/pressure on the operating element V Volume adjustment by rotational movement of the operating element