Source: https://patents.google.com/patent/EP1767950B1/en
Timestamp: 2019-09-18 04:09:42
Document Index: 716915782

Matched Legal Cases: ['art\n317', 'art\n318', 'art\n319', 'art\n339', 'arts 316', 'arts 316']

EP1767950B1 - Method and apparatus for accurate positioning of a pipetting device - Google Patents
EP1767950B1
EP1767950B1 EP20050077157 EP05077157A EP1767950B1 EP 1767950 B1 EP1767950 B1 EP 1767950B1 EP 20050077157 EP20050077157 EP 20050077157 EP 05077157 A EP05077157 A EP 05077157A EP 1767950 B1 EP1767950 B1 EP 1767950B1
EP20050077157
EP1767950A1 (en
2005-09-21 Application filed by F Hoffmann-La Roche AG, Roche Diagnostics GmbH filed Critical F Hoffmann-La Roche AG
2007-03-28 Publication of EP1767950A1 publication Critical patent/EP1767950A1/en
2008-08-20 Publication of EP1767950B1 publication Critical patent/EP1767950B1/en
The invention concerns a method for positioning pipettes.
The invention further concerns an analyzer that comprises means for carrying out such a method.
Automatic analyzers, and in particular clinical chemistry analyzers, comprise an automatic pipetting unit with which pipetting operations are performed in a plurality of fixed positions. Even after thorough mechanical adjustment of the position of the pipetting needle during manufacture of the analyzer, the sum of the manufacturing tolerances of the various components of the analyzer and the deformations of the needle with time cause deviations of the position of the pipetting needle and make it difficult to have the pipetting needle properly aligned with the fixed pipetting positions it is expected to be positioned at by a transport device of the automatic pipetting unit. In order to have the pipetting needle properly aligned with the fixed pipetting positions, the operation of the analyzer has to include an initialization process which is carried out at each start of operation of the analyzer and which is suitable for positioning the pipetting needle at a reference, initial or home position, which in a cartesian system is designated by the coordinates X0, Y0 and Z0 of the tip of the pipetting needle, and which is also called the zero position of the pipetting needle. Once the latter reference position is determined, the transport system of the pipetting needle should be able to position the needle accurately at each pipetting position.
The task of providing such a reliable initialization process is particularly difficult when the transport device moves the pipetting needle only along a straight line, e.g. in X-direction only, and all pipetting positions are located in that linear path of the motion of the pipetting needle. A reliable initialization process is even more difficult to achieve when the portion of the pipetting needle which is introduced into a vessel for effecting a pipetting operation is moved along a circular path within the vessel for mixing liquids introduced in that vessel. In the latter case, a very accurate alignment of the pipetting needle and the vessel is required.
Documents US5443791 and US5270210 disclose alignment procedures for pipetting systems. Both are related to different pipetting devices with a different structure: US5443791 concerns a pipette linearly moveable by a robotic arm in the X-Y-Z directions and US5270210 concerns a pipette moveable only in a circular motion. None of those system discloses the use of an excenter mechanism arranged in a linearly moveable pipette and its specific alignment procedure.
According to a first aspect of the invention the above mentioned first aim is achieved by a method defined by claim 1.
A second aim of the invention is to provide an analyzer which comprises means for carrying out the method according to the invention.
According to a second aspect of the invention the above mentioned second aim is achieved by means of an analyzer defined by claim 2.
A third aim of the invention is to provide a method of use of an analyzer which comprises means for carrying out the method according to the invention.
According to a third aspect of the invention the above mentioned third aim is achieved by means of a method of use defined by claim 3.
The main advantage obtained with a method and an apparatus according to the invention is that it makes possible
to achieve a reliable initialization method at low cost, because it uses means available in the analyzer for other purposes, namely an excenter mechanism primarily used for performing mixing of liquids by moving the pipetting needle along a circular path, and level detection means which are primarily used for detecting contact of the pipetting needle with a liquid surface during pipetting operations, and
to accurately position a pipetting needle in a plurality of pipetting positions.
shows a perspective view of an analyzer according to the invention.
shows a perspective view of conveyor 11 in Fig. 1.
shows a side view of conveyor 11 in Fig. 1.
shows a perspective view of a cuvette array according to the invention comprising a cuvette holder 41 and a plurality of cuvettes 31 of the type shown in Figures 8-10.
shows a top plan view of the cuvette array shown in Fig. 4.
shows a cross-sectional view taken along a plane C-C in Fig. 5 of a chamber of cuvette holder 41 and of a cuvette 31 held by that chamber.
shows a cross-sectional view taken along a plane D-D in Fig. 5 of a chamber of cuvette holder 41 and of a cuvette 31 held by that chamber.
shows a perspective view of a reaction cuvette 31 of the type which is preferably used with a cuvette holder 41 according to the invention.
shows a first side.view of reaction cuvette 31 in Fig. 8.
shows a second side view of reaction cuvette 31 in Fig. 8.
shows a perspective view of reagent container assembly 61 when it is removed from the analyzer shown in Fig. 1.
shows a top view of the conveyor part of the analyzer shown in Fig. 1 when reagent container assembly 61 is removed therefrom.
shows a cross-sectional view taken along a plane H-H in Fig. 12.
shows a perspective view of reagent container assembly 61 installed in the analyzer, but without its cover and without any reagent container in it.
shows a top view of the conveyor part of the analyzer shown in Fig. 1 and in particular reagent container assembly 61 before it is loaded with reagent containers.
shows a perspective view of a single reagent container.
shows a cross-sectional view taken along a plane I-I in Fig. 16.
shows a cross-sectional view of a reaction cuvette 31 and of a pipetting needle 72 positioned therein.
shows a perspective view of the analyzer of Fig. 1 including covers 316, 317, 318 with openings through which pipetting operations are performed with pipetting needle 72.
shows a schematic top view of the analyzer and in particular the arrangement of the pipetting openings.
shows a perspective view of the structure which holds pipetting needle 72 and moves it along a circular path for mixing liquid contained in a reaction cuvette.
shows a schematic perspective view of the structure shown in Fig. 22 suitable for explaining the operation of this structure.
shows a schematic partial cross-sectional view of the structure shown by Fig. 23.
shows a cross-sectional view of the structure shown by Fig. 23.
shows a schematic top view of the structure shown by Fig. 23 with connecting plate 334 in a first position, with pipetting needle on the symmetry axis 342 of guide 333.
shows a schematic top view of the structure shown by Fig. 23 connecting plate 334 in a second position, with pipetting needle outside of the symmetry axis 342 of guide 333.
shows a top view of reference member 321 in Fig. 1.
illustrates the step of rough mechanical adjustment of the position of the pipetting needle in the analyzer.
illustrates a first step of a method for determining a reference, initial or home position for the pipetting needle.
illustrates a second step of the method for determining a reference, initial or home position for the pipetting needle.
illustrates a third step of the method for determining a reference, initial or home position for the pipetting needle.
illustrates a fourth step of the method for determining a reference, initial or home position for the pipetting needle.
illustrates a fifth step of the method for determining a reference, initial or home position for the pipetting needle.
is a diagram showing parameters related to the methods steps one to four illustrated by Figures 25 to 28.
is a diagram showing parameter related to the correction of the angular position of the excenter device to compensate for an error ΔX caused by an error in the initial angular position of needle 72 due to inaccuracy in the initial position of the excenter device.
is a diagram showing parameter related to the deviation of the position of the pipetting needle in Y-direction necessary after the correction of the error in the initial angular position of needle 72.
is a diagram showing parameters related to the correction of the angular position of conveyor 11 to compensate for the deviations in X- and Y-direction.
is a schematic top view of the pipetting needle in the washing position and shows the deviations in X- and Y-direction of the position of the pipetting needle and the corresponding correction angle α.
is a schematic partial top view of conveyor 11 showing the theoretical angle β1 between the linear motion path of the pipetting needle and a radius passing through the center of a reaction cuvette 31 positioned in a cavity of conveyor 11.
is a schematic partial top view of conveyor 11 showing a corrected angle β2 between the linear motion path of the pipetting needle and a radius passing through the center of a reaction cuvette 31 positioned in a cavity of conveyor 11.
22 conveyor driving means / tooth wheel
35 bottom of cuvette 31
54 cavity/second chamber within bucket
60a intermediate wall
71 automatic pipetting unit / automatic pipetting device
74 transport head for transporting pipetting needle 72
312 first opening for pipetting reagents
313 second opening for pipetting reagents
314 opening for pipetting into reaction cuvettes
315 opening for pipetting into chamber of an ISE device
316 cover part
317 cover part
318 cover part
319 opening giving access to reference member 321
320 pipetting axis
321 reference member for initialization process
322 opening on one side of reference member 321
323 opening in the central part of reference member 321
324 limit stop
325 limit stop
328 symmetry axis of opening 323
331 excenter shaft
332 excenter motor
333 guide
334 connecting table
335 connecting piece
336 elongated opening of guide 333
337 ball bearing pin
338 frame part
339 bushing
341 rotation axis of excenter shaft 331
342 symmetry axis of guide 333
343 arrow indicating the sense of rotation of excenter shaft 331
344 arrow indicating the sense of the motion of needle 72 along a circular path
345 inner side surface of opening 323
346 inner side surface of opening 323
347 inner side surface of opening 323
348 inner side surface of opening 323
349 inner side surface of opening 323
351 theoretical cuvette axis
352 corrected angular position of the cuvette axis / radius that coincides with the corrected angular position of the cuvette axis
353 center of circular path of pipetting needle 72
361 circular path of needle 72
362 circular path of needle 72
363 circular path of needle 72
364 circular path of needle 72
365 circular path of needle 72
366 circular path of needle 72
372 circular path of pipetting needle 72
373 position of pipetting needle 72 after correction of angular position of conveyor with correction angle δ
374 position of circular path 372 after correction of angular position of conveyor with correction angle δ
381 schematic representation of excenter which moves needle 72 along a circular path
382 inner radius of washing station
383 outer radius of washing station
As shown by Fig. 1 an analyzer according to the invention, e.g. a clinical-chemistry for analyzing sample-reagent mixtures contained in reaction cuvettes. The analyzer shown in Fig 1 comprises a rotatable conveyor 11 for conveying reaction cuvettes 31 inserted in corresponding cavities of that conveyor along a circular path, at least one array of reaction cuvettes 31, a hollow body 51 (shown in Fig.14) arranged in the central part of conveyor, a reagent container assembly 61 installed in a cavity 54 of hollow body 51, a sample tube area 18 located adjacent to conveyor 11, an automatic pipetting unit 71, a photometer 21 located adjacent to conveyor 11, and conveyor driving means 22 for rotating conveyor 11.
Reaction cuvettes 31 inserted in the above mentioned cavities of conveyor 11 are loosely held by a cuvette holder 41 described hereinafter in particular with reference to Figures 4 to 7. Such a cuvette holder 41 loosely holds a plurality of reaction cuvettes 31. A cuvette holder 41 and reaction cuvettes 31 held by cuvette holder 41 form a cuvette array. The analyzer comprises at least one such array. Usually reaction cuvettes of a plurality of such cuvette arrays are installed in corresponding cavities of conveyor 11. In the example shown by Fig. 1, conveyor 11 has cavities for receiving 60 reaction cuvettes distributed in 6 cuvette arrays each array having 10 reaction cuvettes.
As shown by Fig. 17, reagent container assembly 61 contains a plurality of chambers 65, 66 for receiving reagent containers 63, 64, like reagent container 62 in Fig. 18, each of which contains a specific reagent in liquid form. Each reagent container carries an automatically readable label (not shown), e.g. a barcode label, which identifies the specific reagent contained in the reagent container.
Automatic pipetting unit 71 comprises a removably mounted pipetting needle 72 and a transport device mounted on a rail 73 which extends in the X-direction shown in Fig. 1. This transport device moves the pipetting needle 72 in two ways: along a rectilinear path in the X-direction, e.g. for bringing pipetting needle 72 to a pipetting position, and along a circular path, e.g. when the tip of pipetting needle 72 is immersed in a liquid contained in a reaction cuvette. The latter circular movement of the pipetting needle 72 is achieved by means of.an excenter mechanism which is part of the above-mentioned transport device of pipetting needle 72. The excenter mechanism is adapted for moving the tip of pipetting needle along a circular path, but keeping the length axis of pipetting needle 72 in the Z-direction shown in Fig. 1. This circular motion of the pipetting needle is used e.g. for mixing in a reaction cuvette 31 a liquid sample and a reagent which have been pipetted into the reaction cuvette. For this mixing purpose the circular motion of pipetting needle 72 is effected with the tip of pipetting needle 72 partially immersed in the sample-reagent-mixture contained in a reaction cuvette 31.
The size of the space available for the upper end portion 34 of a reaction cuvette 31 in each chamber 43 of cuvette holder 41 is chosen large enough to allow displacement of the upper end portion 34 of reaction cuvette in X-, Y, and Z-direction within chamber 43 and within limits determined by the size of chamber 43. The upper end portion 34 of reaction cuvette 31 and thereby the entire cuvette 31 is thus free to rotate around its length axis 31 within angular limits determined by the size of chamber 43.
During the insertion of cuvettes 31 in respective cavities 13 of conveyor 11, are loosely held by cuvette holder 41, but this holder exerts no force or influence on the position each cuvette takes in a cavity 13. The own weight of each cuvette 31 is the only force that acts on it as it is inserted into a cavity 13. The accurate and defined positioning of cuvette 31 in cavity 13 is essentially determined by edges of the inner surface of bottom wall 56 of cavity 13 and the close match of shape and dimensions of cuvette 31 and the cavity 13.
EXAMPLE OF A NEEDLE TRANSPORT DEVICE WHICH IS PART OF AUTOMATIC PIPETTING UNIT 71
As already described above, the analyzer shown by Fig. 1 comprises
a rotatable conveyor 11 for conveying reaction cuvettes 31 along a circular path,
conveyor driving means 22 for rotating said conveyor in a step-wise manner,
an automatic pipetting unit 71 having a pipetting needle 72 for pipetting samples and reagents into the reaction cuvettes 31, thereby forming liquid sample-reagent-mixtures.
The location of the above-mentioned pipetting positions is illustrated by Fig. 20 which shows a perspective view of the analyzer of Fig. 1 including a cover composed of three cover parts 316, 317, 318. These cover parts have the following openings for performing pipetting operations with pipetting needle 72 : a first opening 312 for taking a reagent volume from a reagent container, a second opening 313 for taking a reagent volume from a reagent container, a third opening 314 for performing pipetting operations in one of the reaction cuvettes on conveyor 11, a fourth opening 319 for contacting a reference member 321 for the initialization method and for accessing washing station 23 and a fifth opening 315 for performing pipetting operations in a chamber of an ISE device.
The above mentioned openings in cover parts 316, 317, 318 are also shown by the top plan view represented in Fig. 21. This Figure also shows on the right side the sample area 18 and the upper openings of cavities 19 each of which is adapted for receiving a sample tube. The centers of the openings of cavities 19 are further pipetting positions to which pipetting needle 72 has to be brought to by transport head 74.
Needle transport head 74 comprises an excenter mechanism for moving pipetting needle 74 along a circular path and keeping the length axis of needle 72 parallel to a vertical axis, e.g. parallel to the Z-axis in Fig. 1.
Fig. 22 shows a perspective view of the structure of transport head 74 which holds pipetting needle 72 and moves it along a circular path for mixing liquid contained in a reaction cuvette 31.As shown by Fig. 22 transport head 74 comprises an excenter shaft 331 driven by a motor 332 with shaft 331 and motor 332 mounted on a frame part, and a connecting plate 334 which slides within a guide 33. Pipetting needle 72 is connected by a connecting piece 335 to an end part of connecting plate 334.
EXAMPLE OF A METHOD FOR INITIALIZING THE NEEDLE TRANSPORT DEVICE OF AUTOMATIC PIPETTING UNIT 71
Fig. 28 shows a top plan view of reference member 321. Reference member 321 is a small metallic plate which has the shape shown by Fig. 28 and a thickness of about 5 to 10 mm.
As shown by the top plan view of Fig. 28, opening 323 has e.g. the shape of a pentagon ABCDE and comprises a rectangular zone ABCE and triangular zone CDE which have a common symmetry axis 328 which coincides with pipetting axis 320. Points M and N lie on symmetry axis 328. Triangular zone CDE is an isosceles right triangle and is composed of two isosceles right triangles DNE and DNC.
Before carrying out the initialization method according to the invention for determining a reference point (X0, Y0 ,Z0) for a pipetting needle 72 of an automatic pipetting unit having a needle transport device of the above-described type, a rough adjustment of the position of the pipetting needle 72 comprises automatically driving the transport head 74 of the pipetting needle along rail 73 towards a first limit stop 324 shown in Fig. 21 to define a first limit position for the needle 72 and then driving the transport head 74 of the pipetting needle along rail 73 in the opposite sense towards a second limit stop 325 shown in Fig. 21 to define a second limit position for the needle 72 along pipetting axis. On the basis of data obtained by the determination of these limit positions, the automatically controlled transport head 74 is able to position needle 72 at certain desired positions along pipetting axis 320 for carrying out the initialization method described hereinafter. In addition, a rough adjustment of the initial position of the excenter mechanism is carried out by the above-mentioned light barrier device.
This initial rough adjustments are followed by a method according to the invention described hereinafter for determining a reference point (X0, Y0 ,Z0) for a pipetting needle 72 of an automatic pipetting unit having a needle transport device of the above-described type. This method is described with reference to Figures 30-37 and comprises the following steps:
(i) A first measuring step for measuring a first displacement error ΔX in a displacement of pipetting needle 72 effected by the above mentioned transport device along a straight line in a first direction (pipetting axis 320, which is e.g. parallel to the X-axis), the first error ΔX being caused by a corresponding first angular error ϕ of an initial angular position of the pipetting needle along the circular path determined by the excenter mechanism.
(1) automatically placing pipetting needle 72 on axis 320 and approximately in the center of opening 323, actuating the excenter mechanism to bring needle 72 to its 12 o'clock position shown by Fig. 30, and displacing needle 72 with transport head 74 towards inner side surface 346 of opening 323 until contact is detected with the level detection means associated with needle 72 in order to determine a value X12x corresponding to the position of needle 72 when that contact is detected, and
(2) automatically placing pipetting needle 72 again on axis 320 and approximately in the center of opening 323, actuating the excenter mechanism to bring needle 72 to its 6 o'clock position shown by Fig. 31, displacing needle 72 with transport head 74 towards inner side surface 347 of opening 323 until contact is detected with the level detection means associated with needle 72 in order to determine a value X6x corresponding to the position of needle 72 when the latter contact is detected.
With the values X12x and X6x measured in step (1) respectively step (2) the above mentioned displacement error ΔX is calculated by the formula Δ ⁢ X = X ⁢ 12 ⁢ x - X ⁢ 6 ⁢ x
and the above mentioned error ϕ of the initial angular position of pipetting needle 72 is calculated by the following formula: ϕ = arcsin X ⁢ 12 ⁢ x - X ⁢ 6 ⁢ x 2 ⋅ r M
Fig. 36 is a diagram showing the parameters involved in the determination of ΔX and ϕ. In Fig. 36, rN = radius of pipetting needle 72.
The above mentioned determinations of ΔX and angular error ϕ are followed by
(ii) A first correcting step for correcting the above mentioned displacement error ΔX by means of a corresponding correction of error ϕ of the initial angular position of pipetting needle 72. After this correction pipetting needle is positioned on pipetting axis 320 at a corrected position in X-direction and approximately in the center of opening 323.
The first correcting step is followed by
(iii) A second measuring step for measuring a second displacement error ΔY in a displacement of pipetting needle 72 in a second direction (Y-axis) perpendicular to the vertical plane (parallel to plane X-Z). The second displacement error ΔY is caused by a corresponding second angular error α of an initial angular position of pipetting needle 72 along its circular path determined by the excenter mechanism.
(3) automatically placing pipetting needle 72 on axis 320 and approximately in the center of opening 323, actuating the excenter mechanism to bring needle 72 to its 12 o'clock position shown by Fig. 32, and displacing needle 72 with transport head 74 towards inner side surface 348 of opening 323 until contact is detected with the level detection means associated with needle 72 in order to determine a value X12y corresponding to the position of needle 72 when that contact is detected,
(4) automatically placing pipetting needle 72 again on axis 320 and approximately in the center of opening 323, actuating the excenter mechanism to bring needle 72 to its 6 o'clock position shown by Fig. 33, displacing needle 72 with transport head 74 towards inner side surface 349 of opening 323 until contact is detected with the level detection means associated with needle 72 in order to determine a value X6y corresponding to the position of needle 72 when the latter contact is detected.
With the values X12y and X6y measured in step (3) respectively step (4) the above mentioned displacement error ΔY is calculated by the formula Δ ⁢ Y = X ⁢ 12 ⁢ y - X ⁢ 6 ⁢ y 2 .
This value is negative, when ΔY lies above the X-axis in Fig. 35.
The above mentioned error a of the initial angular position of pipetting needle 72 is calculated by the following formula: α = - arc ⁢ sin Δ ⁢ Y r m
Fig. 37 is a diagram showing the parameters involved in the determination of ΔY and α. In Fig. 37, rM = radius of the circular path of pipetting needle 72.
Fig. 39 is a schematic top view of the pipetting needle 72 in the center of washing position 23 and shows the deviations in X- and Y-direction of the position of the pipetting needle and the corresponding correction angle α.
The above mentioned determinations of ΔY and angular error α are followed by
(iv) A second correcting step for correcting the second displacement error ΔY by means of a corresponding angular change α of the angular position of pipetting needle 72 along its circular path.
The second correcting step is followed by
(v) A third measuring step for determining the position of a vertical reference line, said reference line being a line where said pipetting needle contacts a fixed first reference plane surface in the apparatus, said first plane surface lying in a plane (Y-Z) perpendicular to said straight line in said first direction (X-axis).
(5) automatically placing pipetting needle 72 on axis 320 and approximately in the center of opening 323, actuating the excenter mechanism to bring needle 72 to its 3 o'clock position which as shown by Fig. 34 puts needle 72 in pipetting axis 320, and displacing needle 72 with transport head 74 towards inner side surface 345 of opening 323 until contact is detected with the level detection means associated with needle 72 in order to determine a reference line with coordinates X0, Y0 which corresponds to the position of needle 72 when the latter contact is detected.
The third measuring step is followed by
(vi) A fourth measuring step for determining the position of a reference point (X0, Y0 ,Z0) along the above mentioned reference line, said reference point being the point where the tip of said pipetting needle contacts a fixed second reference plane surface in the apparatus, said second reference plane surface lying in a plane (parallel to plane X-Z) perpendicular to the reference line. For determining the coordinate Z0 of the reference point, it is e.g. convenient to automatically drive needle 72 towards a top horizontal surface of washing station 23 which as shown by Fig. 20 lies in the vicinity of reference member 321 and to detect contact of the tip of needle 72 with that horizontal top surface by means of the level detection device operatively associated with pipetting needle 72.
EXAMPLE OF A METHOD FOR FINE ADJUSTMENT OF THE ANGULAR POSITION OF THE CONVEYOR AFTER THE ABOVE DESCRIBED INITIALIZATION OF THE NEEDLE TRANSPORT DEVICE OF AUTOMATIC PIPETTING UNIT 71
Fig. 40 shows the predetermined angular position β 1 of conveyor 11 for placing a reaction cuvette 31 on conveyor 11 in pipetting position 314 shown by Fig. 21. Fig. 40 shows pipetting axis 320 and axis 351 of cuvette 31.
After execution of the above described initialization process for automatically determining a reference position for pipetting needle 72, the corrections ΔX and ΔY in the position the needle 72 cause a certain deviation of the needle from the center of a reaction cuvette positioned by step-wise rotation of conveyor 11 in pipetting position 314 shown by Fig. 21. In order to compensate for this deviation of the relative position of pipetting needle 72 with respect to reaction cuvette 31, and in line with a further aspect of the invention the predetermined angular position β 1 of conveyor 11 is corrected of an angle δ and this puts conveyor in a corrected angular position β 2 .
The required value of β 2 .and is calculated by the following formula δ β 2 = arc ⁢ sin a x - Δ ⁢ Y r R
δ = β 2 - β 1
The correction ΔX achieved by that correction is given by the formula Δ ⁢ X = r M ⋅ cos α + r R ⁢ cos β 1 - cos β 2
Fig. 38 is a diagram showing parameters related to the calculation of β 2, the corrected angular position of conveyor 11 necessary for compensating the deviations in X-and Y-direction introduced by execution of the above described initialization method. In Fig. 38 a full circle shows the position of pipetting needle 72 before the angular position of conveyor 11 is corrected of an angle δ and circle 373 shows the position of needle after that correction. In Fig. 38 a full circle 372 shows the circular path of pipetting needle 72 before the angular position of conveyor 11 is corrected of an angle δ and circle 374 shows the circular path of pipetting needle 72 after that correction. In Fig. 38 rR represents the radius of conveyor 11.
Fig. 41 is a schematic partial top view of conveyor 11 showing a corrected angle β2 between the linear motion path of the pipetting needle 72 along pipetting axis 320 and a radius 352 passing through the center of a reaction cuvette 31 positioned in a cavity of conveyor 11 when cuvette 31 is at its correct angular position. Fig. 41 also shows the position of pipetting needle 72 with respect to cuvette 31 after the above described correction of the angular position of conveyor 11.
Although preferred embodiments of the invention have been described using specific terms, such description is for illustrative purposes only, and it is to be understood that changes and variations may be made without departing from the scope of the following claims.
A method for determining a reference position for a pipetting needle which is part of an automatic analytical apparatus which comprises
(a) a rotatable conveyor (11) for conveying reaction cuvettes (31) along a circular path,
(b) conveyor driving means (22) for rotating said conveyor in a step-wise manner,
(c) an automatic pipetting unit (71) having a pipetting needle (72) for pipetting samples and reagents into said reaction cuvettes (31), thereby forming liquid sample-reagent-mixtures,
said automatic pipetting unit (71) having a needle transport device for moving said pipetting needle along a straight line in a first direction (X-axis) to a plurality of pipetting positions all of which have centers that lie in one and the same vertical plane (X-Z-plane) which passes through said straight line,
said needle transport device comprising an excenter mechanism for moving said pipetting needle along a circular path and keeping the length axis of said needle parallel to a vertical axis,
(d) level detection means for detecting contact of said pipetting needle with a liquid surface in a vessel or with a metallic part of the apparatus, and
(e) a reference member (321) for determining a reference position,
(i) a first measuring step for measuring a first displacement error (ΔX) in a displacement of said pipetting needle effected by said transport device along said straight line in said first direction (X-axis), said first error (ΔX) being caused by a corresponding first angular error (ϕ) of an initial angular position of said pipetting needle along said circular path determined by said excenter mechanism, said first measuring step comprising actuating the excenter mechanism of the pipette needle to bring the needle in contact with the reference member,
(ii) a first correcting step for correcting said first displacement error (ΔX) by means of a corresponding correction of said angular error (ϕ) of said initial angular position of said pipetting needle,
(iii) a second measuring step for measuring a second displacement error (ΔY) in a displacement of said pipetting needle in a second direction (Y-axis) perpendicular to said vertical plane, said second displacement error (ΔY) being caused by a corresponding second angular error (α) of an initial angular position of said pipetting needle along said circular path determined by said excenter mechanism, said second measuring step comprising actuating the excenter mechanism of the pipette needle to bring the needle in contact with the reference member,
(iv) a second correcting step for correcting said second displacement error (ΔY) by means of a corresponding change (α) of the angular position of said pipetting needle along said circular path,
(v) a third measuring step for determining the position of a vertical reference line, said reference line being a line where said pipetting needle contacts a fixed first reference plane surface in the apparatus, said first plane surface lying in a plane (Y-Z) perpendicular to said straight line in said first direction (X-axis), and
(vi) a fourth measuring step for determining the position of a reference point ((X0, Y0 ,Z0) along said reference line, said reference point being the point where the tip of said pipetting needle contacts a fixed second reference plane surface in the apparatus, said second reference plane surface lying in a plane (X-Z) perpendicular to said reference line.
An automatic analytical apparatus,
said automatic pipetting unit (71) having a needle transport device for moving said pipetting needle along a straight line to a plurality of pipetting positions all of which have centers that lie in one and the same vertical plane which passes through said straight line, and
said needle transport device comprising an excenter mechanism for moving said pipetting needle along a circular path, keeping the length axis of said needle parallel to a vertical axis,
(d) level detection means for detecting contact of said pipetting needle with a liquid surface in a vessel or with a metallic part of the apparatus,
(e) a reference member (321) for determining a reference position for the pipetting needle and for positioning the pipetting needle in said reference position by a method according to claim 1, and
(f) electronic circuit means for controlling the operation of said conveyor driving means, said needle transport device, said level detection means and said means for determining a reference position for the pipetting needle and for positioning the pipetting needle in said reference position.
A method of use of the analytical apparatus according to claim 2, characterized in that
after positioning of the pipetting needle in said reference position by a method according to claim 1 the angular position of the conveyor (11) is modified to take into account changes in the position of said pipetting needle with respect to the position of a reaction cuvette (31) on said conveyor (11), said changes being introduced when carrying out said method according to claim 1,
said modification of the angular position of said conveyor (11) being a change (δ) of the angular position of the conveyor, said change (δ) being calculated taking into account said first displacement error (ΔX) and said second displacement error (ΔY).
EP20050077157 2005-09-21 2005-09-21 Method and apparatus for accurate positioning of a pipetting device Active EP1767950B1 (en)
DE200560009194 DE602005009194D1 (en) 2005-09-21 2005-09-21 Method and device for the precise positioning of a pipetting
AT05077157T AT405842T (en) 2005-09-21 2005-09-21 Method and device for the precise positioning of a pipetting
ES05077157T ES2313200T3 (en) 2005-09-21 2005-09-21 Method and apparatus for exact positioning of a pipetting device.
JP2006253486A JP4620023B2 (en) 2005-09-21 2006-09-19 Method and apparatus for accurate positioning of the pipette device
US11/524,008 US7585678B2 (en) 2005-09-21 2006-09-20 Method and apparatus for positioning a pipetting device
CA 2560459 CA2560459C (en) 2005-09-21 2006-09-20 Method and apparatus for accurate positioning of a pipetting device
CN 200610139578 CN1936589B (en) 2005-09-21 2006-09-20 Method and apparatus for accurate positioning of a pipetting device
EP1767950A1 EP1767950A1 (en) 2007-03-28
EP1767950B1 true EP1767950B1 (en) 2008-08-20
EP20050077157 Active EP1767950B1 (en) 2005-09-21 2005-09-21 Method and apparatus for accurate positioning of a pipetting device
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