Manually actuated sampling pipette comprising an absolute volume counter

Abstract

The invention relates to a manually actuated sampling pipette (1) comprising a volume counter (22) comprising: - at least one drive gear (26) rotated by the adjustment screw (14); - a first follower gear (30a) having a number of teeth Z1; - a second follower gear (30b) having a number of teeth Z2 different from the number of teeth Z1; - a first angle sensor (38a) configured to determine a first angle A1 of the first gear (30a); - a second angle sensor (38b) configured to determine a second angle A2 of the second gear (30b); - a system (42) for determining the angular position of the adjustment screw (14) from the pair of values (angle A1; angle A2).

Description

[0001] DESCRIPTION

[0002] TITLE: MANUALLY OPERATED SAMPLING PIPETTE INCLUDING AN ABSOLUTE VOLUME COUNTER

[0003] TECHNICAL FIELD

[0004] The present invention relates to the field of single-channel or multi-channel sampling pipettes, also called laboratory pipettes, or air-displacement or positive-displacement liquid transfer pipettes, intended for the calibrated sampling and introduction of liquid into containers.

[0005] More specifically, the invention relates to manually operated sampling pipettes, intended to be held in the hand by an operator during liquid sampling and dispensing operations.

[0006] The invention relates more particularly to the means used to adjust the volume of liquid to be taken.

[0007] STATE OF PRIOR ART

[0008] Conventional pipettes have a volume adjustment screw, which is rotated by a pipette control knob, via a control rod connecting this knob to the volume adjustment screw. Other volume adjustment solutions are known, such as an adjustment wheel not connected to the pipette control rod.

[0009] The most common counter on hand-operated pipettes is based on a mechanical design, driven by the rotation of the adjustment screw. The counter, for example, comprises three drums marked from 0 to 9, each displaying a single digit visible through a slot. The lower drum is secured to the rotation of the screw by a key that moves in a slot in the adjustment screw. The screw can therefore translate, which modifies the upper stop of the pipette, but only its rotation is perceived by the counter.

[0010] To count multiple turns of the screw, the lower drum drives the middle drum via a ratchet mechanism, which allows the middle drum to turn a tenth of a turn when the lower drum goes from 9 to 0, after completing a complete turn. The same mechanism is used between the middle drum and the upper one. Thus, the counter can count one hundred turns, before returning to its initial state. Usually, of these one hundred turns, only ten to fifty are used, depending on the pipette model. On each of the drums, dashes are added between the numbers, thus making it possible to distinguish one hundred nuances on each drum, thus increasing the precision of the pipette. This results in a resolution of the mechanical counter of the order of 3.6°, or + / - 1.8°.

[0011] This resolution is adequate, but it remains perfectible. Therefore, one of the primary goals of the present invention is to improve the design of the pipette and its volume counter, so as to increase its resolution. Another goal is to improve the ergonomics of volume adjustment and its reading on the pipette screen.

[0012] STATEMENT OF THE INVENTION

[0013] To meet this aim, the invention relates to a manually operated sampling pipette comprising a fixed pipette body, as well as a system for adjusting the volume of liquid to be sampled, the adjustment system comprising:

[0014] - a screw for adjusting the volume to be sampled, centered on a screw axis;

[0015] - a control member for rotating the adjustment screw;

[0016] - a volume counter cooperating with the adjustment screw, characterized in that the volume counter comprises:

[0017] - at least one drive gear, rotated by the adjusting screw;

[0018] - a first follower toothed wheel, meshing with said at least one drive wheel and having a number of teeth Zi;

[0019] - a second follower toothed wheel, also meshing with said at least one drive wheel and having a number of teeth Z2 preferably different from the number of teeth Zi;

[0020] - a first angle sensor designed to determine a first angle Ai of the first follower gear, within the range of values ​​[0°; 360°[;

[0021] - a second angle sensor designed to determine a second angle A2 of the second follower gear, within the range of values ​​[0°; 360°[;

[0022] - a system for determining the angular position of the adjustment screw relative to its axis, this angular position being between 0 and N turns, from the pair of values ​​(angle Ai; angle A2), the volume counter being configured so that each pair of values ​​(angle Ai; angle A2) corresponds to a single angular position of the adjustment screw.

[0023] The design proposed by the present invention differs radically from those known for manually operated pipette counters. The accuracy and resolution of the counter are greatly increased compared to the existing one. For example, the accuracy can be of the order of + / - 1°, and the resolution of the order of + / - 0.005°, all with high reliability and low power consumption.

[0024] Furthermore, the principle specific to the invention makes it possible to give a correct result, even after a power supply fault.

[0025] It also allows for possible integration in a limited space, such as that encountered in a manually operated sampling pipette. Indeed, the proposed invention makes it possible to obtain both an absolute count of the number of turns of the screw, and significant precision, without using a mechanism with a high reduction ratio. The solution therefore occupies little space and remains very simple mechanically, implying a low manufacturing cost of the assembly.

[0026] The volume counter according to the invention also has the advantage of being able to easily replace a conventional mechanical counter in the existing pipette fleet.

[0027] It is noted that the invention can be provided with a number of follower gears greater than two, to further increase the precision and / or the resolution and / or the number of revolutions possible for the adjustment screw, even if this can logically lead to a larger footprint. Nevertheless, it is noted that even with two follower gears, by judiciously choosing the number of teeth thereof, it is possible to encode a very large number of revolutions.

[0028] Finally, it is specified that the link between the number of turns (corresponding to the angular position determined for the adjustment screw), and the sampling volume, is obtained in a conventional way from the characteristics of the pipettes on which the electronic counter is mounted, namely the diameter of the piston and the pitch of the screw. Calibration data, or possibly even data on environmental conditions, can also be used to establish the sampling volume.

[0029] The invention preferably has at least one of the following optional features, taken alone or in combination.

[0030] Preferably, said at least one drive gear wheel consists of a single drive gear wheel having a number of teeth Zo, the numbers of teeth Zi and Z2 being preferably each less than the number of teeth Zo, and the drive gear wheel and the two follower gear wheels are preferably arranged in the same plane orthogonal to the screw axis.

[0031] Alternatively, the numbers of teeth Zi and Z2 may be greater than the number of teeth Zo. Another alternative consists of providing, for example, two drive gears, and not just one, these two drive gears then cooperating respectively with the two follower gears. In the latter case, the gears may be arranged two by two in different parallel planes, to save space depending on the transverse direction of the pipette. In this solution, it is noted that the two drive gears may have different or identical numbers of teeth. If they are different, the numbers of teeth Zi and Z2 of the two follower gears may also be different from each other, or identical.

[0032] Preferably, the volume meter comprises:

[0033] - a first magnetic assembly comprising a first magnet integral in rotation with the first follower toothed wheel, as well as the first magnetic angle sensor, designed to determine the first angle Ai of the first follower toothed wheel, corresponding to the angle of the first magnet, included in the range of values ​​[0°; 360°[;

[0034] - a second magnetic assembly comprising a second magnet integral in rotation with the second follower toothed wheel, as well as the second magnetic angle sensor, designed to determine the second angle A2 of the second follower toothed wheel, corresponding to the angle of the second magnet, included in the range of values ​​[0°; 360°[ .

[0035] However, even if the magnetic solution just described is preferred for angle sensors, these can be of different design, for example optical, capacitive, etc.

[0036] Preferably, the first and second angle sensors are each configured to measure the angle of the magnetic field of the associated magnet, in a measurement plane of the sensor.

[0037] This type of sensor is therefore not a magnetometer strictly speaking, because it does not measure the intensity of the magnetic field, but only its angle with a high resolution. The resolution of the sensor is higher when it is close to a magnet and the magnetic moment of the magnet is high.

[0038] Preferably, each of the first and second magnets is concentric with its associated angle sensor, and / or the spacing between each of the first and second magnets and its associated angle sensor is of the order of 1 mm.

[0039] These preferred data provide the best results in terms of precision and / or resolution. Preferably, the numbers of teeth Zi, Zî are prime to each other, and the difference between these two numbers of teeth Zi, Zî is preferably equal to one.

[0040] When the two numbers of teeth Zi, Z2 are prime to each other, this allows the angle offset between the two magnets to remain slow relative to the number of teeth used, and thus allows a large number of revolutions to be encoded, while providing a small footprint. In addition, when the difference in the number of these teeth is equal to one, this implies that the dimensions of the two follower toothed wheels are similar, which facilitates their installation in the pipette.

[0041] Preferably, the volume meter is designed so that the number of turns N of the screw, and the numbers of teeth Zo, Zi, Z2, satisfy the following formula:

[0042] It should be noted that the ideal combination is not necessarily the one that allows the highest number of turns to be encoded for the screw. Indeed, the number of teeth on the follower wheels must allow the number of turns required for the screw to be encoded, but ideally not more, in order to take full advantage of the resolution over the useful range.

[0043] In this regard, it is noted that according to this formula:

[0044] - Zo, the number of teeth on the drive wheel, tends to reduce the number of turns N that can be encoded for the adjustment screw;

[0045] - the maximum number of encodable rounds N typically increases with the product of Zi by Z2;

[0046] - the term | Z2-Z11 in the denominator shows that to encode a large number of revolutions N while limiting the number of teeth, the numbers of teeth Zi and Z2 must have the smallest possible difference, and therefore preferably only one tooth difference.

[0047] Preferably, the number of turns N of the screw is twelve, the number of teeth Zo is thirty-five, the number of teeth Zi is twenty, and the number of teeth Z2 is twenty-one.

[0048] This combination of preferred values ​​corresponds to an optimized solution that meets many criteria, including:

[0049] - the induced size of the teeth on the wheels is not too small (for example with a "module" greater than 0.3 or 0.35), which advantageously allows for castings to be considered, and for tolerance of play in the gear; - the internal diameter of the drive wheel is greater than a given value, for example

[0050] 10 mm, to allow the passage of the adjustment screw;

[0051] - the maximum size reached by all three wheels remains below a given limit value, for example by fitting within a circle with a maximum radius of 14 mm, in relation to the possibilities of installing the counter in the pipette.

[0052] In any case, it is noted that the maximum number of rounds N is not necessarily an integer, but it can be a rational number.

[0053] Preferably, each of the first and second magnets is fixed on a face of its associated follower wheel, extending orthogonally or substantially orthogonally to an axis of rotation of this follower wheel.

[0054] Preferably, each of the first and second magnets is a cylindrical magnet of diametrical magnetization, and the axis of the cylinder of which crosses orthogonally or substantially orthogonally a measurement plane of the associated sensor.

[0055] Preferably, the drive gear is arranged centered around the adjusting screw.

[0056] This results in a gain in compactness of the counter, for greater ease of installation in the pipette. Other solutions could however be considered, but with a larger footprint.

[0057] Preferably, the pipette comprises a pipetting control rod secured in rotation to the screw for adjusting the volume to be sampled, the member for controlling the rotation of the adjustment screw being a control button secured in rotation to the end of the control rod.

[0058] Alternatively, the system for adjusting the volume to be sampled may comprise a control wheel not connected to the pipetting control rod, or any other type of adjustment system known to those skilled in the art, without departing from the scope of the invention.

[0059] Preferably, the volume adjustment system comprises a display, preferably provided to display the volume set or being set, or more generally for displaying data, and the adjustment system is preferably designed to allow at least one of the following actions:

[0060] - data collection; - transmission of data to the outside world;

[0061] - receiving data from outside.

[0062] Preferably, said system for determining the angular position of the adjustment screw relative to its axis, from the pair of values ​​(angle Ai; angle A2), comprises a calculator.

[0063] The invention also relates to a method for determining a volume to be sampled from a manually operated sampling pipette as described below, comprising a step of determining the angular position of the adjustment screw relative to its axis, from the pair of values ​​(angle A1; angle A2).

[0064] Other advantages and characteristics of the invention will appear in the detailed non-limiting description below.

[0065] BRIEF DESCRIPTION OF THE DRAWINGS

[0066] This description will be made with regard to the attached drawings, among which;

[0067] [Fig.l] represents a front view of a manually operated sampling pipette, according to the invention;

[0068] [Fig.2] represents a partial perspective view of the pipette shown in the previous figure;

[0069] [Fig.3] represents a perspective view of a system for adjusting the volume of liquid to be sampled, according to a preferred embodiment of the invention;

[0070] [Fig.4] represents a perspective view of part of the adjustment system shown in the previous figure, installed within the pipette;

[0071] [Fig.5] is a perspective view similar to the previous one, showing in more detail the volume meter of the adjustment system shown in the previous figures;

[0072] [Fig.6] represents a part of the pipette in perspective cut transversely, and revealing the volume counter;

[0073] [Fig.7] represents a cross-sectional view of the main elements of the volume meter; and

[0074] [Fig.8] represents a graph showing the angular position of each of the two follower wheels of the counter shown in the preceding figures, as a function of the number of revolutions made by the drive wheel of this counter. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0075] Referring firstly to Figure 1, a manually operated sampling pipette 1 is shown, of the single-channel or multi-channel type.

[0076] The pipette 1, also called an air displacement or positive displacement pipette, here manual, comprises in the upper part a fixed body forming a handle 2, as well as a lower part 4 intended to integrate at its lower end a sampling cone-holder tip (not shown). This tip is provided to carry a cone, also called a consumable and intended to be ejected from the tip by an ejector system 6, once the pipetting operations are completed. Other ejection systems than that shown in Figure 1 can nevertheless be envisaged, without departing from the scope of the invention.

[0077] The pipette 1 comprises a control button 8 intended to be actuated by the thumb of an operator, in order to carry out the various pipetting operations such as the sampling of the liquid, and its distribution. The button 8 is mounted on the upper end of a pipetting control rod 10 intended to be moved in translation during the aforementioned pipetting steps, along a longitudinal central axis 12 of the pipette. Preferably, the button 8 is integral in rotation with the rod 10, just as the latter has a lower end cooperating with a screw 14 for adjusting the volume to be sampled, visible in FIG. 2. This cooperation is such that the control rod 10 is integral in rotation with the screw 14, their axes preferably being merged, and preferably corresponding to the longitudinal central axis 12 of the pipette.

[0078] The screw 14 for adjusting the volume to be sampled is part of a system 20 for adjusting the volume of liquid, specific to the present invention, and a preferred embodiment of which will be described with reference to FIGS. 2 to 8.

[0079] First of all, it is noted that in a known manner, the rotation of the adjustment screw 14 causes its translation along the axis 12, and possibly the translation of another part, in order to axially move a piston housed in a suction chamber of the lower part 4 of the pipette. It is the adjustment of the high position of this piston which makes it possible to influence the volume subsequently sampled during pipetting. Indeed, the link between the number of turns of the screw 14 and the button 8, and the sampling volume, is obtained from the characteristics of the pipette 1, in particular the diameter of the piston and the pitch of the screw 14. The calibration data, or possibly even the data on the environmental conditions, can also participate in establishing the sampling volume.In addition to the adjustment screw 14, the volume adjustment system 20 also includes the control button 8 and the control rod 10, but also an absolute volume counter 22, preferably of magnetic design. It also preferably includes a digital display 24, intended to display the value of the adjusted volume through a window 7 of the handle 2. The display 24 here preferably has four digits, the magnetic counter then being called “four digits”. This type of counter provides very high precision compared to existing counters. In relation to what will be described later, it is noted that the display can also display other information than the volume, such as the state of the pipette, the state of charge of the battery, the number of cycles, the number of calibrations, the date, or even data from internal / external sensors such as temperature, etc.

[0080] The system 20 further comprises other elements, shown schematically in the figures and attached to the numerical reference 25 corresponding for example to a battery, a wireless charging system, a communication module (wired or wireless) with computer hardware remote from the pipette, etc.

[0081] The volume adjustment system 20, easily implantable on existing manual pipettes, is preferably designed to allow the collection of data, in particular pipetting data on the number of pipetting cycles, the volumes taken, the operating conditions, etc., but also designed to ensure the transmission of this data to the outside, and / or the reception of data from the outside.

[0082] The magnetic volume meter 22 firstly comprises a gear system equipped with a toothed drive wheel 26, centered on the axis 12, directly driven in rotation by the adjustment screw 14. This drive is carried out for example via a lug 27 projecting inwards from the wheel 26, and housed in a longitudinal groove 28 of the screw 14, as can be seen in Figures 6 and 7. The drive wheel 26 has a number of teeth Zo, corresponding here preferably to thirty-five teeth. Its internal diameter is preferably greater than 10 mm, in order to allow the passage of the screw 14 intended to slide relative to this drive wheel 26, which remains fixed in translation relative to the axis 12.

[0083] This drive wheel 26 meshes with a first follower toothed wheel 30a, having a number of teeth Zi, preferably corresponding here to twenty teeth. The drive wheel 26 also meshes with a second follower toothed wheel 30b, having a number of teeth Zi, preferably corresponding here to twenty-one teeth. In all cases, the number of teeth Zi is different from the number of teeth Zi, both preferably less than the number of teeth Zo. In addition, a gap of only one tooth is preferably retained between the numbers of teeth Zi and Z2.

[0084] The three wheels 26, 30a, 30b are preferably arranged in the same transverse plane of the pipette, orthogonal to the axis 12. Their size is such that the assembly formed by these three wheels can be housed in a circle of restricted radius, preferably less than 14 mm, in order to facilitate its installation in the hollow fixed body 2 of the pipette.

[0085] The axes of rotation 32a, 32b of the follower wheels 30a, 30b are thus parallel to the axis 12, on which the drive wheel 26 is centered.

[0086] The counter 22 also comprises a first magnetic assembly 34a, comprising a first magnet 36a integral in rotation with the first follower toothed wheel. Preferably, the first magnet 36a is fixed on an axial end face of the first follower wheel 30a, and it takes the form of a cylindrical magnet, preferably a disc, of diametrical magnetization and whose axis of the cylinder corresponds to the axis of rotation 32a of the wheel 30a. By way of example, the disc-shaped magnet 36a can be housed in a recess in the upper face of the wheel 30a, as can be seen in the figures. The first assembly 34a also comprises a first angle sensor 38a, of magnetic design, and designed to determine a first angle Ai of the first follower toothed wheel, corresponding here to the angle of the first magnet 36a, included in the range of values ​​[0°; 360°[.

[0087] The axis 30a of the first cylindrical magnet 36a thus passes orthogonally or substantially orthogonally through a measuring plane of the first angle sensor 38a, in which this sensor is inscribed and also corresponding to a transverse plane of the pipette. The magnet 36a is arranged concentrically with its associated sensor 38a, and in the axial direction of the pipette, the spacing between the first magnet 36a and the measuring plane of the first angle sensor 38a can be of the order of 1 mm.

[0088] The first angle sensor 38a is designed to measure the angle Ai of the magnetic field of the magnet 36a, in the measurement plane of this sensor, parallel to the section plane of Figure 7. Consequently, the sensor 38a does not measure the intensity of the magnetic field of the magnet 36a, but only its angle Ai relative to a reference frame also called the zero angle of the sensor, and referenced RI in Figure 7. The resolution of the sensor 38a is higher when it is close to the magnet, as in the invention. The counter 22 also comprises a second magnetic assembly 34b, identical or similar to the first assembly 34a which has just been described. Thus, in the figures, the elements of the second assembly 34b bear the same numerical references as those attached to the elements of the first magnetic assembly 34, only the extension “a” having been modified to extension “b”.

[0089] Therefore, the second magnet 36b and the second magnetic angle sensor 38b are designed to determine the second angle A2 of the second follower gear 30b, corresponding to the angle of the second magnet, included in the range of values ​​[0°; 360°[ . Here again, the sensor 38b does not measure the intensity of the magnetic field of the magnet 36b, but only its angle A2 with respect to a reference frame also called zero angle of the sensor, and referenced R2 in FIG. 7.

[0090] It is noted that the two magnets 36a, 36b are preferably located in the same transverse plane of the pipette, just as the two magnetic sensors 38a, 38b are also located in the same transverse plane of the pipette, both being supported by a printed circuit 40 secured to the pipette body.

[0091] The magnetic counter 22 also comprises a system 42 for determining the angular position of the adjustment screw 14, relative to its axis 12. The system 42, shown schematically in FIG. 7 and preferably comprising a computer 44, is in fact designed to determine the angular position of the screw 14 from the pair of values ​​(angle Ai; angle A2). To do this, the printed circuit 40 can be part of this determination system 42, and deliver the values ​​of the pair (angle Ai; angle A2) from which the angular position Pa of the adjustment screw 14 is determined.

[0092] This angular position Pa of the screw is between 0 and N turns, N not necessarily being an integer, but possibly being a rational number. With the aforementioned design, each pair of values ​​(angle Ai; angle A2) corresponds to a single angular position Pa of the adjustment screw 14. This angular position Pa is written for example as 5 turns and 250°, 7 turns and 75°, 11 turns, etc. It has an extreme value corresponding to N, integer or rational, determined using the following formula: Therefore, the above-mentioned numbers of teeth lead to a value of N equal to twelve revolutions. This implies that during the twelve revolutions of the screw 14 and the drive wheel 26, the pair of values ​​(angle Ai; angle A2) is always different, and therefore refers to a single angular position Pa. It is only after completing the twelfth revolution that this pair of values ​​becomes identical to that observed before the start of rotation of the screw, in its opposite extreme position. In this respect, Figure 8 is a graph showing the evolution of the angles Ai and A2, as the screw 14 and the drive wheel 26 rotate. On this graph, the value of the angle Ai is represented with the thickest dotted line, while the value of the angle A2 is represented with the thinnest dotted line.These two curves clearly show that at each instant during twelve complete turns of the screw, the pair of values ​​(angle Ai; angle A2) is always unique and different. For information purposes, the curves are represented by dotted lines, the visible solid lines only symbolizing the passage from one turn to the next, for each follower wheel 30a, 30b.

[0093] Once the values ​​(angle Ai; angle A2) are known and delivered to the system 42, the latter can be configured in any manner deemed appropriate by those skilled in the art, to lead to the single corresponding value of the angular position Pa of the screw 14. This determination can be carried out for example using a pre-established map indicating the angular position of the screw 14 (in complete turns and in degrees), as a function of the pairs of identified values ​​(angle Ai; angle A2).

[0094] Another possibility is to use calculator 44, and to start from the two angle values ​​of the pair (angle Ai; angle A2), in order to determine a positive difference value "Dp" between these two angles. To do this, when the subtraction between the values ​​of angle Ai and that of angle A2 gives a negative value, 360° is added to the value of angle Ai.

[0095] Then, the calculator 44 can lead to the angular position Pa of the screw, by the following formula:

[0096] Pa = Dp * N / 360

[0097] For example, when the positive difference of angles “Dp” is 180°, the angular position Pa given by the preceding formula leads to a value of six turns, which is also found on the graph of figure 8. These six turns of the screw induce a single volume of liquid which will be sampled, a volume which is then displayed on the display 24. The computer 44 can be made to carry out other operations, in order to obtain even more precise values ​​of the actual angular position Pa of the adjustment screw 14. In addition, it can be configured to calculate and deliver a confidence index each time the actual angular position Pa of the adjustment screw 14 is determined. This confidence index can be displayed, and possibly trigger an alarm for the user when this index is lower than a threshold value.

[0098] For example, the Pa value determined according to the above formula can then be refined using various data, such as the measurement of the two angles Ai, A2, and / or data relating to the kinematics of the gears.

[0099] Still by way of example, further upstream in the process of determining the angular position Pa of the adjustment screw 14, magnetic compensation calculations can be implemented for the determination of each of the two angle values ​​Ai, A2. More precisely, such compensation calculations make it possible to correct the value of each of the two angles Ai, A2 measured by the sensors 38a, 38b, taking into account the cross influence of the first magnet 36a on the second sensor 38b, and vice versa.

[0100] In particular, to determine the aforementioned influence, the direction and intensity of the magnetic field measured from the opposite magnet are taken into account, this makes it possible to calculate an angle offset caused by the opposite magnet, and then to use this offset to add it to or subtract it from the angle measured for each sensor. The two angles Ai, A2 corrected in this way then result in values ​​closer to those which would be measured in the absence of the opposite magnet, which improves the accuracy of the measurement of the angles of the follower wheels 30a, 30b.

[0101] In any case, the proposed design offers particularly high meter accuracy and resolution, respectively of the order of + / - 1° and of the order of + / - 0.005°, while providing high reliability.

[0102] Furthermore, the proposed design also facilitates the assembly of the electronic counter during its manufacture, thanks to a simplified calibration process that can consist of performing 12 revolutions to collect data, then performing calculations using all this data in order to best adjust parameters that maximize the accuracy of the electronic counter. Thus, the bonding of the magnets and the placement of the toothed wheels can be carried out in any way, thereby simplifying the assembly of the electronic counter before its installation in the sampling pipette.

[0103] Finally, it is recalled that a conventional mechanical pipette can only be calibrated at a single point. To do this, so that the counter display coincides with the volume actually collected and dispensed by the pipette, an adequate position of the upper stop of the control rod is sought. The limitation of such a calibration is that if the accuracy curve, corresponding to the difference between the collected volume and the set volume, has a slope, difficulties may be encountered during calibration, so that the pipette remains compliant over its entire volume range.

[0104] Conversely, using the absolute counter implemented in the present invention, the calibration of a pipette equipped with said counter proves to be simpler and more precise thanks to the calculator 44, which can carry out a correction of the volume display so as to maintain a minimal accuracy error over the entire volume range.

[0105] Of course, various modifications may be made by those skilled in the art to the invention which has just been described, solely by way of non-limiting examples, and the scope of which is defined by the appended claims.

Claims

CLAIMS 1. Manually operated sampling pipette (1) comprising a fixed pipette body (2), as well as a system (20) for adjusting the volume of liquid to be sampled, the adjustment system comprising: - a screw (14) for adjusting the volume to be sampled, centered on a screw axis (12); - a member (8) for controlling the rotation of the adjustment screw (14); - a volume counter (22) cooperating with the adjustment screw (14), characterized in that the volume counter (22) comprises: - at least one drive toothed wheel (26), driven in rotation by the adjusting screw (14); - a first follower toothed wheel (30a), meshing with said at least one drive wheel (26) and having a number of teeth Zi; - a second follower toothed wheel (30b), also meshing with said at least one drive wheel (26) and having a number of teeth Z2 preferably different from the number of teeth Zi; - a first angle sensor (38a) designed to determine a first angle Ai of the first follower gear (30a), included in the range of values ​​[0°; 360°[; - a second angle sensor (38b) designed to determine a second angle A2 of the second follower gear (30b), included in the range of values ​​[0°; 360°[; - a system (42) for determining the angular position of the adjustment screw (14) relative to its axis (12), this angular position being between 0 and N turns, from the pair of values ​​(angle Ai; angle A2), the volume counter being configured so that each pair of values ​​(angle Ai; angle A2) corresponds to a single angular position of the adjustment screw (14).

2. Pipette according to claim 1, characterized in that said at least one drive toothed wheel consists of a single drive toothed wheel (26) having a number of teeth Zo, the numbers of teeth Zi and Z2 being preferably each less than the number of teeth Zo, and in that the drive toothed wheel (26) and the two toothed wheels followers (30a, 30b) are preferably arranged in the same plane orthogonal to the screw axis (12).

3. Pipette according to claim 1 or 2, characterized in that the volume counter (22) comprises: - a first magnetic assembly (34a) comprising a first magnet (36a) integral in rotation with the first follower toothed wheel (30a), as well as the first magnetic angle sensor (38a), designed to determine the first angle Ai of the first follower toothed wheel (30a), corresponding to the angle of the first magnet, included in the range of values ​​[0°; 360°[; - a second magnetic assembly (34b) comprising a second magnet (36b) integral in rotation with the second follower toothed wheel (30b), as well as the second magnetic angle sensor (38b), designed so as to determine the second angle A2 of the second follower toothed wheel (30b), corresponding to the angle of the second magnet, included in the range of values ​​[0°; 360°[ .

4. Pipette according to claim 3, characterized in that the first and second angle sensors (38a, 38b) are each designed to measure the angle of the magnetic field of the associated magnet (36a, 36b), in a measuring plane of the sensor.

5. Pipette according to claim 3 or 4, characterized in that each of the first and second magnets (36a, 36b) is concentric with its associated angle sensor (38a, 38b), and / or in that the spacing between each of the first and second magnets (36a, 36b) and its associated angle sensor (38a, 38b) is of the order of 1 mm.

6. Pipette according to any one of the preceding claims, characterized in that the numbers of teeth Zi, Zz are prime to each other, and in that the difference between these two numbers of teeth Zi, Zj is preferably equal to one.

7. Pipette according to any one of the preceding claims combined with claim 2, characterized in that the volume counter (22) is designed so that the number of turns N of the adjustment screw (14), and the numbers of teeth Zo, Zi, Z2, satisfy the following formula:

8. Pipette according to any one of the preceding claims combined with claim 2, characterized in that the number of turns N of the screw is twelve, the number of teeth Zo is thirty-five, the number of teeth Zi is twenty, and the number of teeth Z2 is twenty-one.

9. Pipette according to any one of the preceding claims combined with claim 3, characterized in that each of the first and second magnets (36a, 36b) is fixed on a face of its associated follower wheel (30a, 30b), extending orthogonally or substantially orthogonally to an axis of rotation (32a, 32b) of this follower wheel.

10. Pipette according to claim 9, characterized in that each of the first and second magnets (36a, 36b) is a cylindrical magnet of diametrical magnetization, and the axis of the cylinder of which crosses orthogonally or substantially orthogonally a measurement plane of the associated sensor (38a, 38b).

11. Pipette according to any one of the preceding claims combined with claim 2, characterized in that the drive toothed wheel (26) is arranged centered around the adjustment screw (14).

12. Pipette according to any one of the preceding claims, characterized in that it comprises a pipetting control rod (10) integral in rotation with the adjustment screw (14) of the volume to be sampled, the rotation control member of the adjustment screw being a control button (8) integral in rotation with the end of the control rod (10).

13. Pipette according to any one of the preceding claims, characterized in that the volume adjustment system (20) comprises a display (24) for displaying the volume and / or data, and in that it is preferably designed so as to allow at least one of the following actions: - data collection; - transmission of data to the outside; - receiving data from outside.

14. Pipette according to any one of the preceding claims, characterized in that said system (42) for determining the angular position of the adjustment screw (14) relative to its axis, from the pair of values ​​(angle Ai; angle A2), comprises a calculator (44).

15. Method for determining a volume to be taken from a manually operated sampling pipette (1) according to any one of the preceding claims, characterized in that it comprises a step of determining the angular position of the adjustment screw (14) relative to its axis (12), from the pair of values ​​(angle Ai; angle A2).

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