A device for automatically maintaining tension and control of a drivebelt as the driving direction of the drivebelt is rapidly reversed and when the drivebelt is worn.

FIELD OF THE INVENTION

The present invention relates to a method and apparatus for automatically processing a patient's biological fluids such as urine, blood serum, plasma, cerebrospinal fluid and the like. In particular, the present invention provides a device for automatically maintaining tension and control of a drivebelt as the driving direction of the drivebelt is rapidly reversed and when the drivebelt is worn.

BACKGROUND OF THE INVENTION

Various types of tests related to patient diagnosis and therapy can be performed by analysis of a sample of a patient's infection, bodily fluid or abscess for an analyte of interest. Patient samples are typically placed in sample vials, the vials transported to a clinical laboratory, placed into racks on an automated clinical analyzer and sample is extracted from the vials. Subsequently, samples are combined in reaction vessels with various reagents extracted from reagent cartridges; the mixture is possibly incubated before being analyzed to aid in treatment of the patient. Interrogating measurements, turbidimetric or fluorometric or the like, are made to ascertain end-point or reaction rate values from which the amount of analyte in the sample may be determined, using well-known calibration techniques.

Automated clinical analyzers improve operating efficiency by providing results more rapidly while minimizing operator or technician error. Due to increasing demands on clinical laboratories regarding assay throughput, the efficiency of handling patient samples and reagents within an analyzer continually needs to be increased, and an important factor is the ability to quickly position a plurality of different samples or reagents at an appropriate liquid extraction location.

The sample rack is usually placed by an operator in an input portion of the analyzer and automatically moved by the analyzer to an aliquotting location where an aliquot of the liquid patient sample is extracted, usually by aspiration using a hollow probe from the sample container. Aliquot samples from a number of different patient samples may be dispensed into a plurality of interim vessels or wells formed as an integral array of small open cup-like vessels, herein called an aliquot vessel array, like that described in U.S. patent Ser. No. 10/037,512, assigned to the assignee of the present invention. Aliquot vessel arrays are transported to a sampling location where an appropriate amount of the aliquot sample is extracted by a sampling probe and dispensed by a sampling probe into a reaction cuvette. In addition, reagent(s) required to conduct specified assays are extracted at a reagenting location from appropriate reagent cartridge(s) using hollow probes that are subsequently shuttled to a reagent dispensing location where reagent(s) are dispensed into the reaction cuvette.

In order to maintain high assay throughput, it is advantageous that sampling probes be quickly shuttled between sampling locations and reaction cuvettes and that reagenting probes be quickly shuttled between reagenting locations and reaction cuvettes. It is also advantageous that reagent cartridges be quickly shuttled between on-board storage locations and reagenting locations. In all of these shuttling and positioning operations, it is desirable that the aliquot vessel arrays, reagent cartridges, sampling probes, and reagenting probes be accurately and repeatably positioned at their selected locations. Motorized drivebelts are frequently employed in shuttling operations like described, however the drivebelts are known to stretch from their original dimensions in long term repeated use making it difficult to repeatably position a probe or cartridge or the like at its intended location. Furthermore, when the direction of travel of a drivebelt is rapidly reversed, the drivebelt may dislodge from an associated pulley and belt or sprocket and chain unless it is maintained at a tension of sufficient strength.

SUMMARY OF THE INVENTION

The present invention provides a device to automatically compensate for unknown changes in length of a drivebelt by maintaining a constant tension on a drivebelt regardless of rapid changes in its driving direction so that probes or cartridges or the like may be accurately positioned at their intended location as the drivebelt wears. Such an automatic tensioning device employs a uni-directional latching device adapted to allow a belt-driven tensioner to move only in the direction that increases the distance between the tensioner and the driving source of the driving belt. As the driving belt increases length, a constant tension is maintained thereon.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1, taken withFIG. 2, shows schematically the elements of an automatic chemical analyzer10in which the present invention may be advantageously practiced, analyzer10comprising a reaction carousel12supporting an outer cuvette carousel14having cuvette ports20formed therein and an inner cuvette carousel16having vessel ports22formed therein, the outer cuvette carousel14and inner cuvette carousel16being separated by a open groove18. Cuvette ports20are adapted to receive a plurality of reaction cuvettes24like disclosed in co-pending application Ser. No. 10/623,436 assigned to the assignee of the present invention and containing various reagents and sample liquids for conventional clinical and immunoassay assays while vessel ports22are adapted to receive a plurality of reaction vessels25that contain specialized reagents for ultra-high sensitivity luminescent immunoassays. Reaction carousel12is rotatable using stepwise movements in a constant direction, the stepwise movements being separated by a constant dwell time during which carousel12is maintained stationary and computer controlled assay operational devices13, such as sensors, reagent add stations, mixing stations and the like, operate as needed on an assay mixture contained within cuvettes24and reaction vessels25.

Analyzer10is controlled by software executed by the computer15based on computer programs written in a machine language like that used on the Dimension® clinical chemistry analyzer sold by Dade Behring Inc, of Deerfield, Ill., and widely used by those skilled in the art of computer-based electromechanical control programming. Computer15also executes application software programs for performing assays conducted by various analyzing means17within analyzer10.

Temperature-controlled reagent storage areas26and28store a plurality of multi-compartment elongate reagent cartridges30like that described in co-pending application Ser. No. 09/949,132 assigned to the assignee of the present invention, and containing reagents in wells32as necessary to perform a given assay.

A bi-directional incoming and outgoing sample tube transport system36having input lane34A and output lane34B transports incoming individual sample tubes40containing liquid specimens to be tested and mounted in sample tube racks42into the sampling arc of a liquid sampling arm44. Liquid specimens contained in sample tubes40are identified by reading bar coded indicia placed thereon using a conventional bar code reader to determine, among other items, a patient's identity, the tests to be performed, if a sample aliquot is to be retained within analyzer10and if so, for what period of time. It is also common practice to place bar coded indicia on sample tube racks42and employ a large number of bar code readers installed throughout analyzer10to ascertain, control and track the location of sample tubes40and sample tube racks42.

Sampling arm44supports a liquid sampling probe46mounted to a rotatable shaft48so that movement of sampling arm44describes an arc intersecting the sample tube transport system36and an aliquot vessel array transport system50, as seen inFIG. 3. Sampling arm44is operable to aspirate liquid sample from sample tubes40and to dispense an aliquot sample into one or more of a plurality of vessels52V in aliquot vessel array52, as seen inFIG. 4, depending on the quantity of sample required to perform the requisite assays and to provide for a sample aliquot to be retained by analyzer10within environmental chamber38.

Aliquot vessel array transport system50comprises an aliquot vessel array storage and dispense module56and a number of linear drive motors58adapted to bi-directionally translate aliquot vessel arrays52within a number of aliquot vessel array tracks57below a sample aspiration and dispense arm54located proximate reaction carousel12. Sample aspiration and dispense arm54is controlled by computer15and is adapted to aspirate a controlled amount of sample from individual vessels52V positioned at a sampling location within a track57using a conventional liquid probe54P and then liquid probe54P is shuttled to a dispensing location where an appropriate amount of aspirated sample is dispensed into one or more cuvettes24in cuvette ports20for testing by analyzer10for one or more analytes. After sample has been dispensed into reaction cuvettes24, conventional transfer means move aliquot vessel arrays52as required between aliquot vessel array transport system50, environmental chamber38and a disposal area, not shown.

A number of reagent aspiration and dispense arms60and62comprising a pair of conventional liquid reagent probes,60P and62P, respectively, are independently mounted and translatable between reagent storage areas26and28, respectively. Probes60P and62P comprise conventional mechanisms for aspirating reagents required to conduct specified assays at a reagenting location from wells32in an appropriate reagent cartridge30, the probes60P and62P subsequently being shuttled to a reagent dispensing location where reagent(s) are dispensed into reaction cuvettes24. A number of reagent cartridges30are inventoried in controlled environmental conditions inside reagent storage areas26and28; a key factor in maintaining high assay throughput is the ability to quickly and accurately shuttle reagent cartridges30inside reagent storage areas26and28to reagenting locations for access by probes60P and62P.

Reaction cuvette load station61and reaction vessel load station63are respectively positioned proximate outer cuvette carousel14and inner vessel carousel16and are adapted to load reaction cuvettes24into cuvette ports20sideways as described later and reaction vessels25into vessel ports22using for example a translatable robotic arm65. In operation, used cuvettes24in which an assay has been finally conducted, are washed and dried in a wash station67like disclosed in co-pending application Ser. No. 10/623,360 assigned to the assignee of the present invention. Subsequent assays are conducted in cleaned used cuvettes24unless dictated otherwise for reasons like disclosed in co-pending application Ser. No. 10/318,804 assigned to the assignee of the present invention. Cuvette unload station59is adapted to remove unusable reaction cuvettes24from cuvette ports20again using a translatable robotic arm65like seen on load stations61and63.

A problem often encountered in the process of shuttling reagent cartridges30is that during use, the shuttling mechanism experiences wear adversely affecting the accuracy with which reagent cartridges30are presented to probes60P and62P. Another problem arises when abrupt reversals in the shuttling direction of reagent cartridges30are made at high speed because the change in load experienced by, for example, the driving or the slack portion of a circular drivebelt, causes reagent cartridges30to be stopped at gradually changing locations. The present invention is useful in a cartridge shuttle mechanism64like that shown inFIG. 5and comprises an automated tensioner66to compensate for changes in length a shuttling chain or drivebelt68may experience during use or for changes in tension the drivebelt68may experience during abrupt reversals of direction so that probes60P and62P or cartridges30or the like may be accurately positioned at their intended location as the shuttling chain or drivebelt68wears.

In an exemplary use of automated tensioner66as shown inFIG. 5, motor70is controlled by computer15to circulate drivebelt68in clockwise and counter-clockwise directions, in order to position a cartridge carrier72having a number of reagent cartridges30secured thereon, only one reagent cartridge30being illustrated for purposes of simplicity. Carrier72is shown schematically secured only on one side by tie-down74to only one leg of drivebelt68so that carrier72is free to be driven to and from along the direction of drivebelt68, as indicated by double-ended arrow76. Consequently, cartridge30may be positioned as desired at a reagenting location.

FIG. 6A, a plan view, andFIG. 6B, a side view, show elements of automated tensioner66as comprising a sprocket78rotatably attached to a sprocket-arm80, sprocket-arm80having a leg portion82slideably inserted within a closed end bore89(seeFIG. 7) formed in latching base84, leg portion82maintained in a plane via pin81slideable within groove83also formed in latching base84. An important feature of tensioner66is an elongate latch86and latching spring87, latch86having a latching porthole88(seeFIG. 7B) formed in its central portion, leg portion82being slideably inserted therethrough. Elongate86has a gap89formed between prongs91(FIG. 7B) that fits over an extended ledge85(seeFIG. 7) at the back of latching base84.

FIG. 7Ais an enlarged view of latch86as gap89is positioned over ledge85of latching base84, leg portion82inserted through latching porthole88and disposed within closed bore89(FIG. 7) also illustrating a latching spring87disposed between sprocket-arm80and latch86; a compression spring90(FIG. 7) is also disposed between leg portion82and the end of closed bore89. An important feature of the present invention is a freely hanging first end portion86F adapted to cooperate with a second end portion86S disposed in stationary contact with latching base84. As best seen inFIG. 7A, due to the pressure exerted by latching spring87and the vertical freedom of first end portion86F, latch86, having leg portion82inserted through latching porthole88, will assume a non-perpendicular relationship with leg portion82so that a latching interference is created between latching porthole88of latch86and leg portion82. Consequently, in operation, latching spring87and latch86cooperate in a manner that allows sprocket-arm80to slide “away from” latching base84because a lower force within latching spring87“unlocks” or releases to allow movement between latch86and leg portion82but the latching interference between latching porthole88of and leg portion82prevents sprocket-arm80from moving in the opposite direction “toward” latching base84. A unidirectional latching effect is thereby created by the combined latching spring87and latch86due to the presence of latching porthole88having leg portion82slideably inserted therethrough as is more clearly illustrated inFIG. 8.

FIG. 7Billustrates one embodiment of latch86and latching porthole88in which the stationary end86S of latch86is bifurcated so that a gap89is formed between prongs91, gap89being sized to fit over a projection83of latching base84, best seen inFIG. 7A, thereby preventing rotation of latch86during use.

An important feature of the present invention is a compression spring90disposed between leg portion82and the end of closed bore89acting in a manner to constantly bias leg portion82within closed end bore89outwardly from the end of closed bore89causing tensioner66to automatically increase the separation of sprocket78relative to the location of motor70so that drivebelt68maintains a constant operating tension irregardless of abrupt changes in the direction of drivebelt68and under in-use wear that causes drivebelt68to lengthen. One skilled in the art will appreciate the advantage of the present invention in that it allows use of a high speed, light weight belt or drive chain at low operation tension in conjunction with a relatively smaller motor and relatively low belt tension in contrast to the use of large springs and low speed operation to achieve the same accurate positioning.

FIG. 9is another application of the tensioner66of the present invention in a container shuttle mechanism92for shuttling an elongate container array93having a number of circular vials94having, for example, calibration solutions therein. Motor95is adapted to drive drivebelt96in clockwise and counter-clockwise directions, drivebelt96having container array93constrained between fingers97so that container array93is shuttled bi-directionally along double-headed arrow96A. As in the instance of the previously described cartridge shuttle mechanism64,FIG. 5, the load of the weight of container array93and the rapid reversals in the driving direction of drivebelt96cause the portion of drivebelt96designated96R to alternate between having a taunt or loose tension, depending on whether the container array93is being shuttled towards or away from tensioner66, respectively. Likewise, the portion of drivebelt96designated96L will alternate between having a loose or taunt tension, depending on whether the container array93is being shuttled towards or away from tensioner66, respectively. Again, in order that multiple aspirations of calibration solutions from vials94be made at a accurately positioned location, it is required that drivebelt96be maintained at the same operating tension during use. Wear and subsequent lengthening of drivebelt96during use must be taken into consideration and means provided to compensate therefor. As explained previously, tensioner66is adapted to automatically increase the separation of sprocket78relative to the location of motor95so that drivebelt96maintains a constant operating tension even if drivebelt96is caused to lengthen because of wear during use.

It will be appreciated by those skilled in that art that a number of design variations may be made in the above and still achieve the essence of the present invention. For example, the linearly actuated tensioner may alternatively be configured as an angularly displaced tensioner, employing the same latching mechanism. For these reasons, the present invention is not limited to those embodiments precisely shown and described in the specification but only by the following claims.