Method for dosing a liquid using a pipette and a syringe, and pipette for operating a syringe for dosing a liquid

Abstract

A method for dosing a liquid using a pipette with adjustable dosing step size and an indicating equipment and a syringe that can be operated using the pipette, wherein the syringe is detachably connected to the pipette, at option, the dosing step size is set, or the dosing step size set before is maintained, the dosing volume adjusted via the dosing step size is indicated by means of the indicating equipment, the maximum number of dosing steps possible without refilling the syringe, with the set dosing step size and completely filled syringe is indicated by means of the indicating equipment, liquid is aspirated into the syringe, a reverse stroke is performed after the syringe is filled with liquid, dosing steps are performed, the performed dosing steps are counted and the number of performed dosing steps and/or the number of dosing steps still possible without refilling the syringe is determined and indicated by means of the indicating equipment, after performing the maximum number of dosing steps possible without refilling the syringe, either the syringe is detached from the pipette, or the previous steps are performed anew by means of the same syringe, wherein in the dosing step, the overall performed number of dosing steps with the syringe with the set dosing step size is counted, and/or the number of dosing steps still possible without refilling the syringe is determined and indicated by means of the indicating equipment.

Claims

1. A method for dosing a liquid using a manually operated pipette with adjustable dosing step size and an indicating equipment, which is part of the pipette, and a syringe that can be operated using the pipette, wherein the syringe is detachably connected to the pipette whereby a fixture body of the pipette fastens a portion of a piston of the syringe, and further wherein the fixture body is a hollow-cylindrical fixture body which has a further axially oriented opening for inserting and gripping levers for holding a fastening portion for fastening the portion of the piston of the syringe, the dosing step size is set, or the dosing step size set before is maintained, the dosing volume adjusted via the dosing step size is indicated by means of the indicating equipment, the maximum number of dosing steps possible without refilling the syringe, with the set dosing step size and completely filled syringe, is indicated by means of the indicating equipment through a control equipment, liquid is aspirated into the syringe by manually actuating a pick up lever of the pipette which dislocates the fixture body within a housing of the pipette from a lower end position to an upper end position, the lower end position and the upper end position being end positions of the dislocation of the fixture body, and a reverse stroke of the fixture body and the piston is performed by manually actuating an actuation button of the pipette after the syringe is filled with liquid before dosing steps are performed, the fixture body cooperating with a lower detection means in the lower position thereof indicating that the fixture body is located in the lower end position, and an upper detection means detecting an execution of reverse stroke, wherein when liquid is being aspirated into the syringe, the fixture body is dislocated from the lower detection means which sends a signal to the indicating equipment for an indication by blinking until the fixture body activates the upper detection means and when a reverse stroke is executed thereafter, the upper detection means are actuated by the actuation button and send a signal to the indicating equipment for blinking as long as a reverse stroke has been performed, dosing steps are performed by manually actuating the actuation button, after the reverse stroke is performed, the performed dosing steps are counted and a number of performed dosing steps and/or a number of dosing steps still possible without refilling the syringe is determined and indicated by means of the indicating equipment, after performing the maximum number of dosing steps possible without refilling the syringe, either the syringe is detached from the pipette, or the previous steps are performed anew by means of the same syringe, wherein in the dosing steps, the overall performed number of dosing steps with the syringe with the set dosing step size is counted, and/or the number of dosing steps still possible without refilling the syringe is determined and indicated by means of the indicating equipment.

2. The method according to claim 1, wherein an encoding specifying a syringe volume of the syringe that is connected to the pipette is detected by the pipette, and the dosing volume is determined on the basis of the set dosing step size and the detected encoding, and is indicated by means of the indicating equipment.

3. The method according to claim 1, wherein an indication referring to the pick-up of liquid is indicated by means of the indicating equipment before liquid is picked up using the syringe that is detachably connected to the pipette.

4. The method according to claim 1, wherein while liquid is being picked up, an indication, blinking or in other ways referring to the actual process of picking up liquid into the syringe and to the execution of the reverse stroke, is indicated by means of the indicating equipment for so long until a reverse stroke has been performed.

5. The method according to claim 1, wherein after the complete execution of the reverse stroke, the set dosing volume and the number of performed dosing steps is indicated by means of the indicating equipment.

6. The method according to claim 5, wherein an indication referring to the delivery of liquid is indicated after the complete execution of the reverse stroke.

7. The method according to claim 1, wherein after performing the maximum possible number of dosing steps, an indication referring to the optional discharge of residual liquid from the syringe and to detaching the syringe from the pipette or to picking up liquid using the same syringe is indicated by means of the indicating equipment.

8. The method according to claim 7, wherein after discharging residual liquid from the syringe, an indication referring to detaching the syringe from the pipette is indicated by means of the indicating equipment.

9. The method according to claim 1, wherein the indication is indicated by means of the indicating equipment only after the syringe is detachably connected to the pipette, and wherein the indication expires when the syringe is being detached from the pipette.

10. The method according to claim 1, wherein after detachably connecting the pipette to the syringe and before picking up liquid into the syringe, an indication referring to positioning the pipette for picking up liquid is indicated by means of the indicating equipment.

11. The method according to claim 1, wherein after the execution of at least one dosing step and before the execution of the maximum possible number of dosing steps, changing the setting of the dosing step size, the newly set dosing volume and the maximum possible number of further dosing steps with the newly set dosing volume without refilling the syringe are indicated by means of the indicating equipment, and the executed number of further dosing steps with the newly set dosing volume is counted and indicated by means of the indicating equipment.

12. The method according to claim 11, wherein after changing the dosing step size, the dosing step size is subsequently reset to the value set before, the maximum possible number of further dosing steps with the dosing step size set before and without refilling the syringe is indicated by means of the indicating equipment, and the dosing steps executed by means of the newly set dosing step size after the resetting, or the overall performed dosing steps before and after the resetting, are counted and indicated by means of the indicating equipment.

13. The method according to claim 1, wherein an indication referring to the execution of a reverse stroke is indicated by means of the indicating equipment, when performing dosing steps after incomplete pick-up of liquid into the syringe, for so long until the reverse stroke is executed by one or several dosing steps, and dosing steps subsequent to this are counted and indicated by means of the indicating equipment.

14. A method for dosing a liquid comprising the steps of: providing a pipette with adjustable dosing step size, the pipette having an attached indicating equipment; providing a syringe that can be operated using the pipette; detachably connecting the syringe to the pipette; setting the dosing step size, or the dosing step size set before is maintained; the dosing volume adjusted via the dosing step size is indicated using the indicating equipment; the maximum number of dosing steps possible without refilling the syringe, with the set dosing step size and completely filled syringe, is indicated using the indicating equipment, aspirating liquid into the syringe by manually actuating a pick up lever of the pipette which cooperates with a hollow-cylindrical fixture body which has a further axially oriented opening for inserting and gripping levers for holding a fastening portion for fastening a portion of a piston of the syringe, the fixture body being dislocated within a housing of the pipette, from a lower end position to an upper end position, the lower end position and the upper end position being end positions of the dislocation of the fixture body, lower detection means detect the lower position of the fixture body indicating that the fixture body is located in the lower end position, and send a signal to an indicating equipment, the pick up lever moving the fixture body from the lower end position to an upper end position; performing a reverse stroke by manually actuating an actuation button of the pipette after the syringe is filled with liquid before dosing steps are performed; performing dosing steps by manually actuating the actuation button, after the reverse stroke is performed, the performed dosing steps being counted and a number of performed dosing steps and/or a number of dosing steps still possible without refilling the syringe is determined and indicated using the indicating equipment, wherein when liquid is being aspirated into the syringe, and the fixture body is dislocated from the lower detection means, which sends a signal to the indicating equipment for an indication, by blinking until the fixture body activates the upper detection means and when the reverse stroke is executed thereafter, the upper detection means are actuated by the actuation button and send a signal to the indicating equipment for blinking as long as the reverse stroke is performed, and after performing the maximum number of dosing steps possible without refilling the syringe, either detaching the syringe from the pipette, or performing the previous steps anew using the same syringe, wherein in the dosing steps, the overall performed number of dosing steps with the syringe with the set dosing step size is counted, and/or the number of dosing steps still possible without refilling the syringe is determined and indicated using the indicating equipment.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

(1) The present invention will be explained in more detail in the following by way of the attached drawings of an example of its realisation. In the drawings show:

(2) FIG. 1 a pipette of the present invention with syringe held therein, in a perspective view from the side;

(3) FIG. 2 the same pipette in a longitudinal section;

(4) FIG. 3 fixture body with tooth bar, connection element, draw-up lever and cover tape of the same pipette in a magnified partial section in the longitudinal direction;

(5) FIG. 4 the same configuration in a perspective partial view from the side;

(6) FIG. 5 the same configuration in a housing half of the pipette in a perspective partial view from another side;

(7) FIG. 6 the draw-up lever mount in a perspective view from the side;

(8) FIG. 7 the draw-up lever carrier in a perspective view from the other side;

(9) FIG. 8 the draw-up lever carrier with inserted cover tape in a perspective view from the side;

(10) FIG. 9 the draw-up lever carrier with inserted cover tape in a further perspective view;

(11) FIG. 10 fixture body with means for relocating the fixture body, comprising draw-up lever, actuation button, pawl, tooth bar, transmission element for a reverse stroke, upper and lower end position switch, in the upper end position in a longitudinal section;

(12) FIG. 11 the same arrangement after a reverse stroke in the same longitudinal section, omitting the front leg of the dosing lever;

(13) FIG. 12 the same arrangement shortly before reaching the lower end position in a longitudinal section, seen from the opposing side;

(14) FIG. 13 the same arrangement in the lower end position in the same longitudinal section;

(15) FIG. 14 the same arrangement in a further longitudinal section through a dosing step sensor for detecting dosing steps when this switch is actuated;

(16) FIG. 15 the end position switches and the dosing step sensor for detecting a dosing step with the dosing lever and a transmission element for a reverse stroke, with not actuated dosing step sensor in a perspective partial view;

(17) FIG. 16 the same arrangement with actuated dosing step sensor in the same perspective partial view;

(18) FIG. 17 method for dosing upon complete filling of the syringe, and indication of the set dosing volume and of the dosing steps in a flow chart;

(19) FIG. 18 method for dosing with fixture body initially not thrust back into the lower end position in a flow chart;

(20) FIG. 19 part of a method for dosing upon change of the dosing step size in a flow chart;

(21) FIG. 20 part of a method for dosing upon change of the dosing step size and subsequent resetting of the dosing step size to the initial value in a flow chart;

(22) FIG. 21 method for dosing upon partial filling of the syringe in a flow chart;

(23) FIG. 22 table with the number of dosing steps for executing a reverse stroke, at different settings of the dosing step size.

DETAILED DESCRIPTION OF THE INVENTION

(24) While this invention may be embodied in many different forms, there are described in detail herein a specific preferred embodiment of the invention. This description is an exemplification of the principles of the invention and is not intended to limit the invention to the particular embodiment illustrated.

(25) In the present application, the designations up and down refer to the orientation of the pipette in which the bar-shaped housing is oriented vertically, and the fixture for the syringe is disposed at the downside.

(26) According to FIG. 1, a pipette 1 has a bar-shaped housing 2, in which a syringe 3 is held at the downside. From a side wall of the housing 2, a draw-up lever 5 projects from the housing 2 above a straight slit 4. An actuation button 8 of a tooth bar pawl control projects from the same side wall of the housing above two further slits 6, 7. Above it, a LCD display 9 is countersunk into the same side wall of the housing 2. Segments of a dial 10 project from openings in the neighbouring side wall.

(27) According to FIG. 2, the syringe 3 has a cylinder 11 and a piston 12 movably arranged therein. The cylinder 11 has a conical portion 13 with a hole 14 for the passage of liquids at the downside, and above it a cylindrical portion 15 in which the piston 12 can be displaced. At the upside, the cylinder 11 has a fastening portion 16 with a circumferential flange 17. A piston rod 18 projects towards the upside from the piston 12, which has a further fastening portion 19 with several circumferential bulges (not shown).

(28) The syringe 3 is arranged with its flange 17 in a fixture 20 at the lower end of the housing 2, which has an axially directed opening 21.1 for insertion and withdrawing of the syringe 3 at the lower end of the housing 2. With its topside, the syringe 3 pushes against a pressure-sensitive ring sensor 22, which scans projections on the upper edge of the flange 17. The flange 17 is kept in the housing 2 in this position by means of gripping levers 23.

(29) The further fastening portion 19 of the piston 12 is disposed in a further fixture 24 in a hollow-cylindrical fixture body 25. The latter has a further axially oriented opening 21.2 for inserting the fastening portion 19. The further fastening portion 19 is held with further gripping levers 26, which engage between the bulges of the further fastening portion 19 or clamp it in.

(30) The fixture body 25 is fixedly connected to a tooth bar 27, which extends below the slit 4 in the longitudinal direction of the housing 2.

(31) A draw-up lever mount 28 is fixed on the fixture body 25 and on a lower part of the tooth bar 27.

(32) Further, there is a draw-up lever carrier 29, which bears against the lower side of the edges of the slit 4 with a sliding board 30. The draw-up lever carrier 29 has an upward-projecting post 31 which grips through the slit 4. Outside of the housing 2, the draw-up lever 5 is fixed on the post.

(33) In the upper half of the housing 2, a dosing lever 34 is pivotally mounted in a hinge bearing 32 in a bulge 33 of the side wall of the housing 2 opposite to the slit 4. The dosing lever 34 has two spaced apart legs 35, 36, which stand out of the two slits 6, 7 on the opposite side wall of the housing 2. The actuation button 8 is fixed there on the projecting ends of the legs 35, 36.

(34) Between the two legs 35, 36 of the dosing lever 34, a pawl 37 is pivotally mounted. The pawl 37 is arranged above the toothing 39 of the tooth bar 27 with a pawl tooth 38. The dosing lever 34 is pressed into the position of FIG. 2 by a not shown spring device. Against the action of the spring device, the dosing lever 34 can be swung towards the downside by actuating the actuation button 8. The pawl 37 is pushed towards the toothing 39 of the tooth bar 27 by a not shown further spring device.

(35) A movable covering 40 is arranged between pawl 37 and tooth bar 27. The covering 40 can be moved by turning the dial 10 which projects laterally out of the housing 2, so that it covers the toothing 39 of the tooth bar 27 more or less.

(36) Further, a circuit board 41 with electronics is arranged in the upper half of the housing 2. Here is also situated a power supply in the form of batteries or accumulators 42.

(37) A further sensor 43 is assigned to the dial 10, which acquires the position of the dial 10. The measurement values determined by the ring sensor 22 and the further sensor 43 are forwarded to the electronics via cable.

(38) The code indicated on the flange 17 designates the size of the respective syringe 3. From the measurement signals provided by the ring sensor 22, the electronics determines the respective syringe size, and from the setting of the dial 10 the respective step width. From these it calculates the set dosing volume and displays it on the display 9.

(39) At the inside, the slits 6, 7 are covered by a diaphragm 44 connected to the dosing lever 34.

(40) According to FIGS. 3 to 5, a flexible cover stripe 45 exists in the housing 2 below slit 4 in order to cover up the slit 4. The cover stripe 45 is made of polypropylene. According to FIG. 8, the cover stripe 45 has eyes 46, 47 at its ends, which are fixed on pins 48, 49 according to FIG. 2, which project from the inner side of that side wall of the housing 2 which has the slit 4.

(41) According to FIGS. 3 to 5, the cover stripe 45 runs through a channel 50 between draw-up lever mount 28 and draw-up lever carrier 29. According to FIGS. 6 and 7, the channel 50 is limited on opposing sides by a lateral surface 51 with a radius of the draw-up lever mount 28 and by a further lateral surface 52 with corresponding radius of the draw-up lever carrier 29. The two lateral limits of the channel 50 are formed by two stripe-shaped side walls 53, 54 of the draw-up lever carrier 29. These are connected to each other by a cross member 55 in a distance from the lateral surface 52 that has the radius. Between the further lateral surface 52 having the radius and the cross member 55, the draw-up lever carrier has a breakthrough 56. From one side of the cross member 55 project two projections 57, 58, which can be put into corresponding pockets 59, 60 of the draw-up lever mount 28. The two stripe-shaped side walls 53, 54 are bridged by a front wall 61, which has the further lateral surface 52 with the radius at the downside, and from which the post 31 projects at the upside.

(42) According to FIGS. 8 and 9, the draw-up lever carrier 29 can be pre-assembled with the cover stripe 45 by guiding the cover stripe 45 along the further lateral surface 52 and across the breakthrough 56, so that it runs on the topside of the cross member 55 between the two stripe-shaped side walls 53, 54. In this configuration, the draw-up lever carrier 29 can be connected to the draw-up lever mount 28 by putting the projections 57, 58 into the pockets 59, 60 and draw-up lever carrier 29 and draw-up lever mount 28 are glued together or snapped together by suitable snapping means. The cover stripe 45 is then arranged in the channel 50 between lateral surface 51, further lateral surface 52 and side walls 53, 54. At one side next to the draw-up lever carrier 29, the cover stripe 45 rests on a projecting rib 51.1 of the draw-up lever mount 28 that extends in the longitudinal direction of the slit 4 (compare FIGS. 4 to 6).

(43) Draw-up lever mount 28 and draw-up lever carrier 29 form together a connection element 62 between fixture body 25 and draw-up lever 5 (compare FIG. 2, 3, 4).

(44) According to FIGS. 4 and 5, the draw-up lever mount 28 has wings 63, 64 which project from both sides. In the example, the wings 63, 64 have a cylindrical shape. They engage into grooves 65, 66 on two opposing side walls of the housing 2. The grooves 65, 66 are limited by an edge of a housing half at one side, and on the other side by a ledge of a chassis in which parts of the drive mechanics of the pipette 1 are mounted.

(45) According to FIG. 2, on the eyes 46, 47, the cover stripe 45 is held stretched at the inner side of the slit 4 by the two pins 48, 49 according to FIG. 8, 9. According to FIG. 3, it is vaulted on the plane in which it extends on both sides of the channel 50 due to the radii of the lateral surfaces 51, 52 of the channel 50. Close bearing of the cover stripe 45 against the edges of the slit 4 is obtained through this.

(46) According to FIGS. 10 and 11, on its lower end at the side facing away from the tooth bar 27, the circuit board 41 carries an upper end position switch 67, formed as a micro-switch, for detecting the upper end position of the fixture body 25. In the upper end position, the fixture body 25 is maximally dislocated away from the fixture 24 (compare FIG. 2) in order to fill a syringe 3 completely. The upper end position switch 67 is a touch button with a touch lever 68 which projects outwardly with respect to the circuit board 41.

(47) The upper end position switch 67 serves for detecting a reverse stroke at the same time. For this purpose, a transmission element 69 for triggering a reverse stroke is arranged adjacent to the tooth bar 27 within the housing of the pipette. The transmission element 69 has a stripe-shaped transmission portion 70, which is guided parallel to the tooth bar 27 in the housing of the pipette and is relocatable. The stripe-shaped transmission portion 70 has a lower end 71 of the transmission element, which is situated in the relocation area of a lower stop 72 which protrudes from the side of the tooth bar 27 when the transmission element 69 is relocated downward.

(48) Further, the transmission element 69 has two control arms 73, 74 at its top, which extend in the plane (vertical to FIGS. 10 and 11) of the circuit board 41 and encompass the lower end of the circuit board 41 on both sides. The transmission element 69 can be relocated such that the control arms 73, 74 arrive in the relocation area of chamfered stop edges 77, 78 on the legs 35, 36 with their control arm ends 75, 76 (FIGS. 10 to 13).

(49) Further, the transmission element 69 has a switch arm 79 at its top, which encompasses the circuit board 41 in a distance on that side on which the upper end position switch 67 is arranged. The switch arm 79 is configured such that it actuates or releases the touch lever 68 of the upper end position switch 67 with its upper switch arm end 80 when the transmission element 69 is relocated. In the situation of FIG. 10, the switch arm 79 actuates the upper end position switch 67, the touch lever 68 being covered by the leg 35 of the dosing lever 34. In FIG. 11 is shown how the switch arm 79 releases the touch lever 68 of the upper end position switch 67.

(50) According to FIGS. 12 and 13, next to its lower end at the side facing the tooth bar 27, the circuit board 41 carries a lower end position switch 81, formed as a micro-switch. The lower end position switch 81 is a touch button with a touch lever 82 projecting towards the circuit board 41. The touch lever 82 is situated in the relocation area of an upper stop 83 which protrudes from the opposite side of the tooth bar 27. In FIG. 12, the upper stop 83 releases the touch lever 82, and in FIG. 13 it actuates it.

(51) According to FIGS. 14 to 16, a dosing step sensor 84 for detecting dosing steps is arranged on the circuit board 41 adjacent to the upper end position switch 67. The dosing step sensor 84 is also a touch button. The touch organ is preferably a membrane made of plate which can be deformed from a stable, outward vaulted starting position to an unstable, inward vaulted position in which is closes an electric circuit. After release, the plate membrane reverts automatically from the unstable to the stable position in which the electric circuit is opened.

(52) With its membrane, the dosing step sensor 84 is situated in the pivot area of a pin 85 made of silicone, which is arranged on a dosing lever base 86 of the dosing lever 34, connecting the legs 35, 36 of the dosing lever 34 and mounted on the hinge bearing 32.

(53) According to FIGS. 2, 10 and 11, the circuit board 41 carries an electronic control equipment 87, which is wired to the ring sensor 22, the further sensor 43 for detecting the rotational position of the dial 10, the upper end position switch 67, the lower end position switch 81, the dosing step sensor 84 and the display 9. The control equipment 87 is further connected to the accumulator 42.

(54) In the utilization of the pipette 1 from FIGS. 1 to 16, a syringe 3 with a syringe size selected by the user is detachably connected to the pipette at first, by putting it into the fixture 20 in the fastening portion 16, and into the fixture 24 with the fastening portion 19, so that the flange 22 is grasped by the gripping levers 23 and the fastening portion 19 by the gripping levers 26.

(55) The ring sensor 22 scans the encoding on the flange 17 of the syringe 3. Based on the signals furnished by the ring sensor 22, the control equipment 87 detects that a syringe 3 is inserted, and switches the display 9 on. Based on the signals furnished by the ring sensor 22 and the sensor 43, the control equipment 87 determines the set dosing volume and indicates it on the display 9. As the case may be, the user changes the setting of the dosing volume by means of the dial 10, and the changed dosing volume is indicated by the display 9.

(56) Further, the control equipment 87 determines the maximum possible number of dosing steps for emptying the syringe 3 after complete filling and indicates it. Further, the control equipment 87 gives a sign by an upward directed arrow on the display 9 that liquid can be picked up into the syringe 3.

(57) In order to draw up liquid through the opening 14 of the syringe 3, the draw-up lever 5 is pushed upward from the position of FIGS. 1, 2 and 13. In the lower end position of the fixture body 25, the upper stop 83 actuates the touch lever 82 of the lower end position switch 81 according to FIG. 13. When the fixture body 25 leaves the lower end position, the upper stop 83 releases the lower end position switch 81, like this is shown in FIG. 12. As soon as the lower end position switch 81 signalizes this to the control equipment 87, the latter triggers a blinking of the indication on the display 9.

(58) When the draw-up motion is ended, the lower stop 72 takes the transmission element 69 along, so that the switch arm 79 pushes against the touch lever 68 of the upper end position switch 67. By this actuation of the end position switch 68, it is signalized to the control equipment 87 that the syringe 3 has been filled completely.

(59) Before the set dosing volume can be delivered stepwise, a reverse stroke must be done. This happens by actuating the actuation button 8. In this, the stop edges 77, 78 hit the control arms 73, 74 and relocate the transmission element 69 downward. The transmission element 69 takes the tooth bar 27 along via the lower stop 72. The clearance is removed from the system by this reverse stroke. Moreover, the switch arm 79 is released from the touch lever 68 of the upper end position switch 67 in this, whereby it is signalized to the control equipment 87 that a reverse stroke has been made.

(60) After the reverse stroke, the display 9 stops blinking and indicates that zero dosing steps have been executed. Further, by displaying a downward directed arrow, the display 9 indicates that liquid can be delivered.

(61) Thereafter, the drawn-up amount of liquid can be delivered in small steps by pushing the actuation button 8 repeatedly downward against the action of the spring equipment. In this, the further spring equipment pushes the pawl 37 with the pawl tooth 38 against the covering 40 until the pawl tooth 38 reaches the lower end of the covering 40. Thereafter, the pawl 37 engages with the pawl tooth 38 into the toothing 39 of the tooth bar 27, and takes the tooth bar 27 somewhat along in the further downward swinging of the dosing lever 34. When the dosing lever 34 is swung up to its arrival on a lower stop, the relocation of the tooth bar 27 depends on a position of the covering 40 set by means of the dial 10. After unloading the actuation button 8, it is pushed upward by the spring equipment, and a further dosing step can be performed.

(62) In each dosing step, the pin 85 hits the dosing step sensor 84 and actuates it (compare FIG. 14). This signalizes the execution of a dosing step to the control equipment 87. The control equipment 87 adds up the executed dosing steps and indicates the respective number of executed dosing steps on the display 9.

(63) Dispensing without having to refill the syringe 3 is possible for so long until the residual amount of liquid remained in the syringe is smaller than the set dosing amount. A residual stroke blocker provides that the covering 40 is swung against the bottom side of the pawl 37, so that the pawl tooth 38 can no more engage into the toothing 39.
Then, the control equipment 87 indicates on the display 9 that the maximum number of dosing steps has taken place. Further, by the indication of a downward directed arrow it gives a sign that either liquid can be aspirated into the syringe 3 anew, or the residual liquid can be drained from the syringe 3 and the syringe 3 can be separated from the pipette 1. In case that further liquid is aspirated into the same syringe 3, the process is like that described above, wherein the control equipment 87 determines the sum of the dosing steps executed with the same set dosing volume, and indicates it on the display 9.
Any residual liquid in the syringe 3 can be discharged by relocating the draw-up lever 5 downward. The lower end position switch is actuated in doing so. Then, the control equipment 87 indicates a downward directed arrow on the display 9, as a sign that the syringe 3 can be separated from the pipette 1. In order to do this, the user actuates the gripping levers 23, 26.
When the draw-up lever 5 is dislocated, the cover stripe 45 is guided through the channel 50. The slit 4 remains always covered. The friction between cover stripe 45 and connection element is acting against any unintended relocation of the fixture body 25, as well as against that of the connection element with the draw up lever 5.
The process mentioned above is illustrated in FIG. 17. In the boxes of the flow chart, the associated indication in the display is given, and with explanations. A set dosing volume of 500 ml is indicated in the example.

(64) The process of FIG. 18 differs from the process of FIG. 17 in that the draw-up lever 5 is not in the lower end position when the pipette 1 is detachably connected to the syringe 3. The control equipment 87 can notice this in that the ring sensor 22 reports the insertion of a syringe 3, and the lower end position switch 81 reports that the fixture body 25 is not in the lowermost end position. In this position, the indication on the indicating equipment 9 (also referred to as a display herein) gives a sign by a downward directed arrow to relocate the draw-up lever 5 downward. Only when this has happened, the set dosing volume, the maximum number of dosing steps and the upward directed arrow are indicated as a hint that the syringe 3 should be refilled. The further process corresponds to that of FIG. 17.

(65) The process of FIG. 19 differs from the process of FIG. 17 in that the setting of the dosing volume is changed in the dispensing. For instance, the dosing volume is altered to 250 ml after a dosing step with a dosing volume of 500 ml. The newly set dosing volume is then indicated by means of the indicating equipment 9, and also the maximum number of possible further dosing steps with this dosing volume and the liquid still remaining in the syringe 3. In the example, these are 8 further steps. Further, the dosing steps which were executed with the newly set dosing volume are counted and indicated.

(66) The process of FIG. 20 differs from the process of FIG. 19 in that the dosing volume is reset to the initial value after the change of the dosing volume. In the example, the dosing volume is changed to a dosing volume of 250 ml after a dosing step of 500 ml. After one dosing step with a dosing volume of 250 ml, the dosing volume is reset to the initial dosing volume of 500 ml. Thereafter, the maximum number of possible further dosing steps with the initial dosing volume and the liquid still remaining in the syringe is indicated. In the dispensing, the dosing steps executed with this dosing amount after the resetting of the dosing amount to the initial value are counted and indicated. In a possible alternative, after the resetting of the dosing amount to the initially set value, the overall executed dosing steps with this dosing amount before and after the resetting, are counted and indicated in the dispensing.

(67) The process of FIG. 21 differs from the process of FIG. 17 in that the syringe 3 is only partially filled. This is detected by the control equipment 87 on the basis of the signals of the lower end position switch 81 and the upper end position switch 67. Namely, when the lower end position switch 81 reports that the fixture body 15 has leaved the lower end position, and thereafter the dosing step counter reports the execution of a dosing step without that the upper end position switch 67 reports the arrival in the upper end position, the syringe has been filled only partially. The control equipment 87 emits then a blinking indication via the display 9. The blinking display further indicates the set dosing volume, the maximum possible number of dosing steps and the upward directed arrow. By the blinking of the display, it is indicated to the user that there is a partial filling, so that achieving the maximum number of dosing steps is not ensured.

(68) The control equipment 87 stops the blinking of the indication only then when the user has executed a sufficient number of dosing steps which correspond to a reverse stroke. Through this, it is indicated to the user that no accurate dosing has taken place, and he/she should throw the delivered dosing amounts away. As soon as the reverse stroke has been done, the control equipment 87 outputs via the indicating equipment 9 the set dosing volume, the number of executed dosing steps and an arrow advising the downward relocation of the fixture body 25.

(69) For each set dosing volume, the control equipment 87 looks up the number of necessary dosing steps for realising a reverse stroke in a memorized table. An example for such a table is given in FIG. 22.

(70) The above processes of FIGS. 17 to 21 can be performed notably by means of the pipette according to FIGS. 1 to 16. The processes of FIGS. 1 to 17 can also be performed by means of other suitable pipettes.

LIST OF REFERENCE SIGNS

(71) 1 pipette 2 housing 3 syringe 4 slit 5 draw-up lever 6 slit 7 slit 8 actuation button 9 display 10 dial 11 cylinder 12 piston 13 portion 14 hole 15 portion 16 fastening portion 17 flange 18 piston rod 19 fastening portion 20 fixture 21.1 opening 21.2 opening 22 ring sensor 23 gripping lever 24 fixture 25 fixture body 26 gripping lever 27 tooth bar 28 draw-up lever mount 29 draw-up lever carrier 30 sliding board 31 post 32 hinge bearing 33 bulge 34 dosing lever 35 leg 36 leg 37 pawl 38 pawl tooth 39 toothing 40 covering 41 circuit board 42 accumulator 43 sensor 44 diaphragm 45 cover stripe 46 eye 47 eye 48 pin 49 pin 50 channel 51 lateral surface 52 lateral surface 53 side wall 54 side wall 55 cross member 56 breakthrough 57 projection 58 projection 59 pocket 60 pocket 61 wall 62 connection element 63 wing 64 wing 65 groove 66 groove 67 upper end position switch 68 touch lever 69 transmission element 70 transmission portion 71 lower end of transmission element 72 lower stop 73 control arm 74 control arm 75 upper end of control arm 76 upper end of control arm 77 stop edge 78 stop edge 79 switch arm 80 upper end of switch arm 81 lower end position switch 82 touch lever 83 upper stop 84 dosing step sensor 85 pin 86 dosing lever base 87 control equipment

(72) The above disclosure is intended to be illustrative and not exhaustive. This description will suggest many variations and alternatives to one of ordinary skill in this art. All these alternatives and variations are intended to be included within the scope of the claims where the term comprising means including, but not limited to. Those familiar with the art may recognize other equivalents to the specific embodiments described herein which equivalents are also intended to be encompassed by the claims.

(73) Further, the particular features presented in the dependent claims can be combined with each other in other manners within the scope of the invention such that the invention should be recognized as also specifically directed to other embodiments having any other possible combination of the features of the dependent claims. For instance, for purposes of claim publication, any dependent claim which follows should be taken as alternatively written in a multiple dependent form from all prior claims which possess all antecedents referenced in such dependent claim if such multiple dependent format is an accepted format within the jurisdiction (e.g. each claim depending directly from claim 1 should be alternatively taken as depending from all previous claims). In jurisdictions where multiple dependent claim formats are restricted, the following dependent claims should each be also taken as alternatively written in each singly dependent claim format which creates a dependency from a prior antecedent-possessing claim other than the specific claim listed in such dependent claim below.

(74) This completes the description of the preferred and alternate embodiments of the invention. Those skilled in the art may recognize other equivalents to the specific embodiment described herein which equivalents are intended to be encompassed by the claims attached hereto.