Patent Description:
An example of a laboratory apparatus known in the field of the invention is the Tecan Cavro Omni Robot, as described in the brochure 'Cavro® Omni Robot' v2. <NUM>, which describes a robotic liquid handing system which comprises a pipette and which is adjustable along the X-, Y- and Z-axis. To establish adjustability along its Z-axis, a so-called 'standard Z-axis' or 'universal Z-axis' positioning assembly may be provided which allows the pipette to be adjustable in Z-position, e.g., in height.

<CIT> describes a positioning device for positioning pipettes in medical-technical applications which includes at least one pipetting apparatus with at least one pipette as well as several drive units for positioning a pipette tip and for moving it over a working area. A sliding carriage is provided which is moveable transversely to the working area, e.g., in Z-position, and supports the pipette.

A further example of a positioning assembly for a pipette is disclosed in <CIT>. The assembly includes a piston member, a first shaft member to move the piston up and down and a rod having a cylindrical space in which the piston member is housed and a pipette mounting portion. The first shaft member is mounted to a first frame and a second frame of the assembly comprises a second shaft member for moving the first frame and the rod in up/down direction. The piston is moved up and down in order to generate a suction force and discharge force respectively.

A still further example of a positioning assembly is disclosed in <CIT>.

A disadvantage of known positioning assemblies for laboratory apparatuses is that such assemblies require a relatively large amount of space in relation to the travel range provided for the device. This may cause the overall size of the positioning assembly, and thereby of the laboratory apparatus, to be relatively large.

It would be advantageous to obtain a positioning assembly which is more compact than known positioning assemblies.

The present invention defines a positioning assembly including a base part and a holder part for holding a device, whereby the assembly further includes a motor for driving a displacement mechanism mounted to the base part, the assembly being configured to adjust a position of the holder part relative to the base part between a retracted position and an extended position, along a linear displacement axis extending in longitudinal direction. The base part and the holder part are arranged parallel to each other and are connected via a displaceable slide link, which is configured to slide on a first guide rail provided on the base part and on a second guide rail provided on the holder part, whereby each guide rail extends in the longitudinal direction.

The slide link is coupled to the displacement mechanism, which causes displacement of the slide link relative to the base part in longitudinal direction. Furthermore, the holder part is moveably coupled to the base part via a coupling arrangement which has a first element provided on the base part, a second element provided on the holder part and a third element provided on the slide link. The first, second and third elements of the coupling arrangement are configured to engage with each other such that linear displacement of the slide link relative to the base part in one direction causes linear displacement of the holder part relative to the slide link in the same linear direction.

Due to the parallel arrangement of the base part and holder part, these parts largely overlap each other in longitudinal direction when the assembly is in retracted position, thus enhancing the compactness of the assembly. At the same time, the coupling arrangement, which causes the holder part to extend when the slide link is displaced in the direction of extension, allows a relatively large extent of linear travel.

The base part and the holder part may be formed by essentially elongate members which have first and second end regions proximal to corresponding first and second longitudinal ends of the respective part. If we define the first end as an upper end and the second end as a lower end, then when the assembly is in a retracted position, the slide link is preferably arranged at an upper region of the base part and at a lower region of the holder part. When the slide link is displaced to the lower end region of the base part, the coupling arrangement causes the holder part to be displaced in the same direction relative to the base part until the extended position is reached in which the slide link is arranged at an upper region of the holder part.

In a first embodiment of the inventive positioning assembly, the first element of the coupling arrangement is a first linear drive surface provided on the base part in longitudinal direction, facing in a transverse direction; the second element of the coupling arrangement is a second linear drive surface provided on the holder part in longitudinal direction, facing the first linear drive surface; and the third element of the coupling arrangement is formed by at least one drive wheel provided on the slide link having a rotation axis in a direction perpendicular to the transverse direction and the longitudinal direction. The at least one drive wheel is arranged such that a circumferential drive surface thereof simultaneously engages the first linear drive surface on the base part and the second linear drive surface on the holder part.

The third element of the coupling element may also be formed by two or more longitudinally spaced drive wheels, each wheel having a circumferential drive surface in engagement with the first and second linear drive surfaces. In one example, the at least one drive wheel is a toothed pinion wheel and the first and second linear drive surfaces have a corresponding notched profile for meshing engagement with the toothed wheel. The first linear drive surface may thus be formed by a toothed rack that is arranged parallel to the first guide rail at a transverse edge of the base part and the second linear drive surface may be formed by a toothed rack that is arranged parallel to the second guide rail, at a transverse edge of the holder part.

In an alternative example of the first embodiment, the circumferential drive surface of the at least one drive wheel and the first and second linear drive surfaces are frictional drive surfaces configured for frictional engagement with each other. The respective drive surfaces may be made from a polymer material such as polyurethane, which has a relative high coefficient of friction.

In a second embodiment of the inventive positioning assembly, the coupling arrangement is executed as a pulley block system. The first element of the coupling arrangement comprises first and second pulley sheaves arranged at first and second longitudinal ends of the base part, whereby the pulley sheaves have a rotation axis extending in the perpendicular direction. The second element of the coupling arrangement is formed by a belt element, first and second ends of which are fixedly attached to the holder part at opposite longitudinal ends thereof. The third element of the coupling arrangement comprises third and fourth pulley sheaves provided on the slide link and spaced in longitudinal direction from each other. Between its first and second ends, the belt element is looped around the third pulley sheave on the slide link, followed by the first pulley sheave on the base part, followed by the second pulley sheave on the base part and then around the fourth pulley sheave on the slide link.

Thus, when the slide link is displaced in longitudinal direction by the displacement mechanism, e.g. from extended position to retracted position, the belt element moves around the rotatable pulley sheaves causing the holder part to be pulled towards its retracted position.

In some examples of the first and second embodiments, the displacement mechanism comprises a lead screw coupled to an output shaft of the motor. Suitably, the lead screw is rotationally mounted to the base part, with a rotation axis extending in longitudinal direction, and is arranged parallel to the first guide rail. The slide link is executed with a mounting portion provided with a threaded bore in which the lead screw engages, such that rotation of the lead screw causes linear displacement of the slide link. The mounting portion may also be configured as a ball nut, whereby an arrangement is provided for recirculating balls that run on raceways formed by opposing threads of the lead screw and threaded bore.

To enhance compactness in linear direction, the lead screw may be arranged parallel to the motor output shaft, whereby the shafts are coupled via a toothed belt or chain that engages with a notched circumferential profile on the lead screw and on the motor output shaft. Alternatively, the motor output shaft and lead screw may be directly coupled and arranged so as to have a common axis of rotation.

In other examples of the second embodiment of the invention, where the coupling arrangement is a pulley block coupling arrangement, the displacement mechanism is partly formed by the belt element and comprises a driven pulley sheave. One of the first and second pulley sheaves on the base part is coupled to the output shaft of the motor and the slide link is coupled to the belt element, such that rotation of the driven pulley sheave causes linear displacement of the slide link. To enhance synchronization between rotation of the motor output shaft and linear displacement of the slide link (and thus also of the holder part) the belt element is preferably a toothed belt or a chain and at least the first and second pulley sheaves on the base part are executed with a corresponding notched circumferential profile for meshing engagement between the belt and the pulley sheaves. It is also possible for the belt element to be executed as a cable or a wire or a smooth belt that frictionally engages with the outer circumference of the pulley sheaves.

In all embodiments of the inventive positioning assembly, the motor may be equipped with a rotatory encoder for tracking the angular position and speed of the output shaft, to enable precise control of the linear position of the slide link and holder part. Alternatively, the assembly may be equipped with a linear encoder for detecting the linear position of the slide link relative to the base part.

In a further aspect, the present invention relates to a laboratory apparatus, such as a liquid handling apparatus that is equipped with one or more positioning assemblies as described above. The base part of each positioning assembly is fixed to the laboratory apparatus and a device such as a pipette or an analysis cartridge is attached to the holder part of the assembly.

These and other aspects of the invention are apparent from and will be elucidated with reference to the embodiments described hereinafter and with reference to the accompanying drawings.

It should be noted that items which have the same reference numbers in different figures, have the same structural features and the same functions.

<FIG> respectively show an example of a positioning assembly <NUM> according to a first embodiment of the invention in a fully retracted position and in a fully extended position. The assembly comprises a base part <NUM> and a holder part <NUM>, which is configured for attachment of a device <NUM>. In the depicted example, the attached device is a pipetting module and comprises a pipette <NUM> for extraction and delivery of a liquid. The holder part <NUM> of the assembly is adjustable relative to the base part <NUM> along a linear translation axis that extends in a longitudinal direction z, to enable the pipette <NUM> to be inserted into and retracted from e.g. a test tube. The holder part <NUM> is arranged parallel to the base part <NUM>, such that in retracted position, the assembly has a compact length L in longitudinal direction z, the length L being defined between a first longitudinal end 120A of the holder part and a second longitudinal end 110B of the base part (refer <FIG>).

Between the fully retracted position shown in <FIG> and the fully extended position shown in <FIG>, the holder part <NUM> has a relatively large extent of linear travel T for such a compact assembly. This is realized according to the invention in that the holder part <NUM> is connected to the base part <NUM> via a displaceable slide link <NUM>. The slide link is displaceable relative to the base part <NUM>, and the holder part <NUM> is displaceable relative to the slide link <NUM>, whereby driven displacement of the slide link in one z-direction causes displacement of the holder part relative to the slide link in the same direction. This will be explained further with reference to <FIG>, which show various and more detailed views of the positioning assembly <NUM> (with no attached device).

The assembly <NUM> includes a displacement mechanism for displacing the slide link <NUM> relative to the base part <NUM> in longitudinal direction z. In this embodiment, the displacement mechanism includes a lead screw <NUM> that is driven by a motor <NUM>, such as a stepper motor, whereby the lead screw and motor are mounted to the base part of the assembly. Suitably, the lead screw <NUM> is rotationally mounted to the base part via at least one bearing, such that the rotation axis extends in longitudinal direction z. To enhance the compactness of the assembly in linear direction z, the lead screw <NUM> is arranged parallel to an output shaft of the motor <NUM> and is driven by drive belt <NUM> (refer <FIG>) that engages with a toothed portion <NUM> on the lead screw and a toothed portion on the motor output shaft (not visible). In other embodiments, the motor and the lead screw may have a common rotation axis.

The slide link <NUM> is mounted to the lead screw and has a mounting portion <NUM> with a threaded bore <NUM> (refer <FIG>) that engages with the lead screw <NUM>, such that driven rotation of the lead screw causes linear translation of the slide link. The base part <NUM> further includes a first guide rail <NUM>, which extends in longitudinal direction z and which fits into a corresponding first slot <NUM> in the slide link, thereby preventing that the link slide rotates with the lead screw and ensuring that the slide link <NUM> is precisely guided in linear direction. The slide link further comprises a second slot <NUM>, parallel to the first slot <NUM>, which engages with a second guide rail <NUM> provided on the holder part <NUM> of the assembly.

The holder part <NUM> is additionally coupled to the base part via a coupling arrangement comprising a first element on the base part, a second element on the holder part and a third element on the slide link, which enables driven displacement of the slide link <NUM> on the base part to cause displacement of the holder part <NUM> relative to the slide link. As best seen in <FIG>, which shows a rear view of the slide link and a portion of the base part and holder part, the slide link is further provided with first and second drive wheels in the form of toothed pinion wheels <NUM>. The arrangement of pinion wheels forms the third element of the coupling arrangement.

The pinion wheels are spaced from each other in longitudinal direction z and are rotatably mounted to the slide link <NUM>, whereby a rotation axis of the pinion wheels extends in x-direction, perpendicular to the longitudinal direction z. The pinion wheels <NUM> are arranged to engage with a first linear drive surface <NUM>, executed as a toothed rack, which is provided on the base part <NUM>, parallel to the first guide rail <NUM> and which faces in transverse direction y. The first rack <NUM> forms the first element of the coupling arrangement. At an opposite circumferential side, the pinion wheels engage with a second linear drive surface, executed as a toothed rack <NUM>, which is provided on the holder part <NUM>, parallel to the second guide rail <NUM>. The second rack <NUM> forms the second element of the coupling arrangement.

Linear displacement of the slide link <NUM> therefore causes rotation of the pinion wheels <NUM>, due to the meshing engagement between teeth of the first rack <NUM> and teeth of the pinion wheels <NUM>. Rotation of the pinion wheels causes linear displacement of the holder part <NUM> relative to the slide link, due to the meshing engagement between teeth of the pinion wheels and teeth of the second rack <NUM>. The slide link <NUM> may also be equipped with a single drive wheel or a plurality of linearly spaced drive wheels, depending on the application.

An advantage of the positive meshing engagement between the pinion wheels and the first and second racks <NUM>, <NUM> is that the linear motion of the slide link <NUM>, driven by rotation of the lead screw <NUM>, can be accurately synchronized with the linear motion of the holder part <NUM>, enabling accurate positioning of a device attached to the holder part. The motor may be equipped with an encoder for tracking the angular position and speed of the output shaft, to enable precise control of the linear position of the slide link and holder part. Alternatively, the assembly may be equipped with a linear encoder for detecting the linear position of the slide link relative to the base part.

and <FIG>, the assembly <NUM> is shown in fully extended position. As indicated by the arrows in <FIG> and with reference to the depicted view, when the slide link is caused to move upwards towards the retracted position (by reversing the rotation direction of the lead screw), the pinon wheels rotate in clockwise direction and the holder part <NUM> is also displaced upwards. The travel of the slide link itself relative to the base part and the holder part occurs in opposite directions. When the slide link travels upwards relative to the base part <NUM>, it travels downwards relative to the holder part <NUM>.

In the fully extended position, the slide link <NUM> is thus arranged such that the pinion wheels <NUM> engage with the second rack <NUM>, in a first (upper) region thereof, which is proximal to the first longitudinal end 120A of the holder part <NUM>. The slide link is further arranged such that the pinion wheels engage with the first rack <NUM> in a second (lower) region thereof, which is proximal to the second longitudinal end 110B of the base part <NUM>. In the fully retracted position, as shown in <FIG>, the link slide is arranged such that the pinion wheels engage with a second (lower) region of the second rack <NUM>, proximal to the second end 120B of the holder part <NUM>, and engage with the first rack <NUM> in a first (upper) region thereof. As mentioned, the assembly is thus compact in longitudinal direction when in the retracted position and allows for a relatively large linear extension of the holder part.

As may be seen from the side view of the assembly shown in <FIG>, the assembly is also compact in transverse direction y, enabling several assemblies to be mounted next to each other on a single apparatus.

A second embodiment of a positioning assembly according to the invention is shown in <FIG>. Like the first embodiment, the <FIG> assembly <NUM> comprises a base part <NUM> to which a motor <NUM> and lead screw <NUM> are mounted. A holder part <NUM> of the assembly is connected to the base part via slide link <NUM>, which engages with the lead screw <NUM> and is guided on first and second linear guide rails respectively provided on the base part and holder part as described for the first embodiment.

In the second embodiment, the coupling arrangement comprises a friction drive. The slide link <NUM> is provided with two drive wheels <NUM> spaced apart in longitudinal direction z. Opposite circumferential sides of the drive wheels <NUM> frictionally engage with a first drive surface <NUM> provided on the base part <NUM> of the assembly and a second longitudinal drive surface <NUM> provided on the holder part <NUM>. The first and second drive surfaces <NUM>, <NUM> extend in the direction of linear travel z, and are arranged parallel to each other at opposing longitudinal edges of the base and holder parts respectively, preferably along the full length of the longitudinal edges. The parallel first and second drive surfaces may also be arranged such that a gap therebetween is somewhat smaller than the diameter of the drive wheels <NUM>. The drive wheels are thus mounted with a slight preload, to ensure that linear displacement of the slide link <NUM> via driven rotation of the lead screw <NUM>, causes rotation of the drive wheels <NUM> due to frictional engagement with the first longitudinal drive surface <NUM>, leading to linear displacement of the holder part <NUM> via frictional engagement with the second longitudinal drive surface <NUM>. A circumferential drive surface of the drive wheels <NUM> and the parallel first and second drive surfaces may be made from a material such as polyurethane, which has a relatively high coefficient of friction.

A third embodiment of a positioning assembly according to the invention is shown in front view in <FIG> and in perspective view in <FIG>. Like the first embodiment, the assembly <NUM> of <FIG> comprises a slide link <NUM> mounted to a motor-driven lead screw <NUM> arranged on the base part <NUM> of the assembly. The slide link <NUM> is guided in longitudinal direction z by a first guide rail <NUM> provided along the length of the base part <NUM>. Again, the slide link <NUM> is connected to the holder part <NUM> and guided thereon in linear direction by a second guide rail <NUM> provided along the length of the holder part.

In this embodiment, the positioning assembly <NUM> is provided with a different coupling arrangement between the base part <NUM>, holder part <NUM> and slide link <NUM>, for causing the holder part to move in the same linear direction relative to the slide link <NUM> when the slide link is displaced in linear direction relative to the base part. The coupling arrangement comprises a belt <NUM>, a first pulley arrangement provided on the base part <NUM> and a second pulley arrangement provided on the slide link <NUM>. The pulley arrangement on the base part consists of a first pulley sheave <NUM> and a second pulley sheave <NUM> provided at opposite ends of the base part in longitudinal direction z. The second pulley arrangement consists of third and fourth pulley sheaves <NUM>, <NUM> provided on the slide link <NUM>, spaced from each other in longitudinal direction z. Each of the sheaves <NUM>, <NUM>, <NUM>, <NUM> has a rotation axis extending in the x-direction.

First and second ends of the belt <NUM> are fixedly attached to the holder part <NUM>, suitably at first and second ends 320A, 320B thereof. The holder part has a longitudinal guide surface <NUM> for the belt, which may be formed by a longitudinal edge of the holder part that faces in transverse direction y towards the base part <NUM>. Starting from the first end 320A of the holder part, the belt <NUM> is guided downwards along an upper portion of the guide surface <NUM>, and is looped under tension around a lower circumferential side of the third pulley sheave <NUM> on the slide link, around an upper circumferential side of the first pulley sheave <NUM> on the base part, then around the lower circumferential side of the second pulley sheave <NUM> on the base part and finally around the upper circumferential side of the fourth pulley sheave <NUM> on the slide link <NUM>. The belt <NUM> is then guided along a lower portion of the longitudinal guide surface <NUM>, before being fixed to the holder part at the second end 320B. The coupling arrangement thus comprises a pulley block system for causing displacement of the holder part <NUM> relative to the slide link <NUM>. As will be understood, the belt <NUM> may be executed as a toothed belt, a chain or a cable/wire.

With reference to the view depicted in <FIG>, where the assembly <NUM> is shown in fully extended position, the slide link <NUM> is arranged at a lower region of the base part <NUM> and at an upper region of the holder part <NUM>. Displacement of the slide link <NUM> towards the retracted position causes displacement of the belt <NUM> around the rotatable pulley sheaves, which in turn causes displacement of the holder part <NUM>. If we define a reference point on the belt indicated by numeral <NUM> in <FIG>, the reference point <NUM> will shift downwards in longitudinal direction z when the lead screw <NUM> is rotated so as to cause the link slide <NUM> to move upwards. This pulls up the second end 320B of the holder part, effecting retraction of the holder. In fully retracted position, the slide link will be arranged at a lower region of the holder part <NUM> and at an upper region of the base part.

A fourth embodiment of a positioning assembly according to the invention is shown in front view in <FIG>.

The positioning assembly <NUM> is provided with the same pulley block coupling arrangement as described for the third embodiment, whereby a belt <NUM> is fixed to opposite ends of the holder part <NUM> and is looped around an arrangement of first and second pulley sheaves <NUM>, <NUM> on the base part <NUM> and a parallel arrangement of third and fourth pulley sheaves <NUM>, <NUM> provided on the slide link <NUM>. In this embodiment, the belt <NUM> not only forms part of the coupling arrangement, but also forms part of the displacement mechanism for displacing the slide link in linear direction z relative to the base part <NUM>.

The slide link <NUM> is attached to the belt <NUM> at a section of the belt that extends in longitudinal direction between the first and second pulley sheaves <NUM>, <NUM> on the base part. As before, the slide link is guided on a first guide rail <NUM> provided on the base part and on a second guide rail <NUM> provided on the holder part. In this embodiment, the first pully sheave <NUM> is driven by a motor <NUM>, which is arranged such that its output shaft has a rotation axis extending in the x-direction. Preferably, the pulley sheaves <NUM>, <NUM> and an engaging inner surface of the belt <NUM> have a toothed profile, for ensuring good synchronization between rotation of the driven pulley sheave <NUM> and linear displacement of the slide link <NUM>.

A positioning assembly according to the invention is particularly suitable for use in laboratory equipment. An example of part of a liquid handling apparatus <NUM> is shown in perspective view in <FIG>. The apparatus is equipped with a first positioning assembly 100A according to the first embodiment, whereby a pipetting module <NUM> is attached to the holder part of the assembly. A further positioning assembly 100B is provided, whereby a gripping device <NUM> is attached to the holder part <NUM>. The gripping device is holding an analysis cartridge in the depicted example. The positioning assemblies adjust the position of the attached devices in z-direction, as explained above. The base part of the first assembly 100A is mounted to a first support <NUM> that extends in y-direction, via a sliding carriage <NUM>, such that the position of the assembly an attached device <NUM> is also adjustable in y-direction. The first support <NUM> is mounted to the apparatus <NUM> on a first rail <NUM> that extends in x-direction, such that the position of the first support in adjustable in x-direction. The further positioning assembly 100B is similarly mounted to the apparatus <NUM>, so as to enable positioning of the assembly in x and y directions.

Claim 1:
A positioning assembly (<NUM>, <NUM>) including a base part (<NUM>, <NUM>) and a holder part (<NUM>, <NUM>) for holding a device (<NUM>, <NUM>), the assembly further including a motor (<NUM>) for driving a displacement mechanism (<NUM>) mounted to the base part, the assembly (<NUM>, <NUM>) being configured to adjust a position of the holder part (<NUM>, <NUM>) relative to the base part (<NUM>, <NUM>) between a retracted position and an extended position, along a linear displacement axis extending in longitudinal direction (z), wherein
- the base part (<NUM>, <NUM>) comprises a first guide rail (<NUM>) extending in the longitudinal direction;
- the holder part (<NUM>, <NUM>) comprises a second guide rail (<NUM>) extending in the longitudinal direction;
- the base part (<NUM>, <NUM>) and the holder part (<NUM>, <NUM>) are arranged parallel to each other and are connected via a slide link (<NUM>, <NUM>) which is configured to slide on each of the first (<NUM>) and second guide rails (<NUM>), and
- the slide link (<NUM>, <NUM>) is coupled to the displacement mechanism (<NUM>), which is configured to displace the slide link (<NUM>, <NUM>) relative to the base part in longitudinal direction (z),
characterized in that:
the holder part (<NUM>, <NUM>) is moveably coupled to the base part (<NUM>, <NUM>) via a coupling
arrangement configured such that linear displacement of the slide link (<NUM>, <NUM>)
relative to the base part (<NUM>, <NUM>) in one direction causes linear displacement of the
holder part relative to the slide link (<NUM>, <NUM>) in the same linear direction, the coupling arrangement comprising:
▪ a first linear drive surface (<NUM>, <NUM>) provided on the base part (<NUM>, <NUM>) in longitudinal direction (z), facing in a transverse direction (y);
▪ a second linear drive surface (<NUM>, <NUM>) provided on the holder part (<NUM>, <NUM>) in longitudinal direction (z), facing the first linear drive surface; and
▪ at least one drive wheel (<NUM>, <NUM>) provided on the slide link (<NUM>, <NUM>) having a rotation axis in a direction (x) perpendicular to the transverse direction (y) and the longitudinal direction (z), arranged such that a circumferential drive surface simultaneously engages the first linear drive surface (<NUM>, <NUM>) on the base part (<NUM>, <NUM>) and the second linear drive surface (<NUM>, <NUM>) on the holder part (<NUM>, <NUM>).