Abstract:
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.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a method and apparatus for automatically processing a patient&#39;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&#39;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. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be more fully understood from the following detailed description thereof taken in connection with the accompanying drawings which form a part of this application and in which: 
         FIG. 1  is a schematic plan view of an automated analyzer in which the present invention may be employed to advantage; 
         FIG. 2  is an enlarged schematic plan view of a portion of the analyzer of  FIG. 1 ; 
         FIG. 3  is a perspective elevation view of an automated aliquot vessel array storage and handling unit; 
         FIG. 4  is a perspective elevation view of an aliquot vessel array; 
         FIG. 5  is a perspective elevation view of a cartridge shuttle mechanism in which the present invention may be used to advantage; 
         FIG. 6A  is a front view of the automated tensioner of the present invention; 
         FIG. 6B  is a side view of the automated tensioner of  FIG. 6A ; 
         FIG. 7  is a perspective cut-away view of key features of the present invention; 
         FIG. 7A  is an enlarged front view of key features of the present invention; 
         FIG. 7B  is perspective view of a latch used within the present invention; 
         FIG. 8  is perspective view of key features of the present invention; and 
         FIG. 9  is a perspective elevation view of a container shuttle mechanism in which the present invention may be used to advantage. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1 , taken with  FIG. 2 , shows schematically the elements of an automatic chemical analyzer  10  in which the present invention may be advantageously practiced, analyzer  10  comprising a reaction carousel  12  supporting an outer cuvette carousel  14  having cuvette ports  20  formed therein and an inner cuvette carousel  16  having vessel ports  22  formed therein, the outer cuvette carousel  14  and inner cuvette carousel  16  being separated by a open groove  18 . Cuvette ports  20  are adapted to receive a plurality of reaction cuvettes  24  like 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 ports  22  are adapted to receive a plurality of reaction vessels  25  that contain specialized reagents for ultra-high sensitivity luminescent immunoassays. Reaction carousel  12  is rotatable using stepwise movements in a constant direction, the stepwise movements being separated by a constant dwell time during which carousel  12  is maintained stationary and computer controlled assay operational devices  13 , such as sensors, reagent add stations, mixing stations and the like, operate as needed on an assay mixture contained within cuvettes  24  and reaction vessels  25 . 
     Analyzer  10  is controlled by software executed by the computer  15  based 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. Computer  15  also executes application software programs for performing assays conducted by various analyzing means  17  within analyzer  10 . 
     Temperature-controlled reagent storage areas  26  and  28  store a plurality of multi-compartment elongate reagent cartridges  30  like that described in co-pending application Ser. No. 09/949,132 assigned to the assignee of the present invention, and containing reagents in wells  32  as necessary to perform a given assay. 
     A bi-directional incoming and outgoing sample tube transport system  36  having input lane  34 A and output lane  34 B transports incoming individual sample tubes  40  containing liquid specimens to be tested and mounted in sample tube racks  42  into the sampling arc of a liquid sampling arm  44 . Liquid specimens contained in sample tubes  40  are identified by reading bar coded indicia placed thereon using a conventional bar code reader to determine, among other items, a patient&#39;s identity, the tests to be performed, if a sample aliquot is to be retained within analyzer  10  and if so, for what period of time. It is also common practice to place bar coded indicia on sample tube racks  42  and employ a large number of bar code readers installed throughout analyzer  10  to ascertain, control and track the location of sample tubes  40  and sample tube racks  42 . 
     Sampling arm  44  supports a liquid sampling probe  46  mounted to a rotatable shaft  48  so that movement of sampling arm  44  describes an arc intersecting the sample tube transport system  36  and an aliquot vessel array transport system  50 , as seen in  FIG. 3 . Sampling arm  44  is operable to aspirate liquid sample from sample tubes  40  and to dispense an aliquot sample into one or more of a plurality of vessels  52 V in aliquot vessel array  52 , as seen in  FIG. 4 , depending on the quantity of sample required to perform the requisite assays and to provide for a sample aliquot to be retained by analyzer  10  within environmental chamber  38 . 
     Aliquot vessel array transport system  50  comprises an aliquot vessel array storage and dispense module  56  and a number of linear drive motors  58  adapted to bi-directionally translate aliquot vessel arrays  52  within a number of aliquot vessel array tracks  57  below a sample aspiration and dispense arm  54  located proximate reaction carousel  12 . Sample aspiration and dispense arm  54  is controlled by computer  15  and is adapted to aspirate a controlled amount of sample from individual vessels  52 V positioned at a sampling location within a track  57  using a conventional liquid probe  54 P and then liquid probe  54 P is shuttled to a dispensing location where an appropriate amount of aspirated sample is dispensed into one or more cuvettes  24  in cuvette ports  20  for testing by analyzer  10  for one or more analytes. After sample has been dispensed into reaction cuvettes  24 , conventional transfer means move aliquot vessel arrays  52  as required between aliquot vessel array transport system  50 , environmental chamber  38  and a disposal area, not shown. 
     A number of reagent aspiration and dispense arms  60  and  62  comprising a pair of conventional liquid reagent probes,  60 P and  62 P, respectively, are independently mounted and translatable between reagent storage areas  26  and  28 , respectively. Probes  60 P and  62 P comprise conventional mechanisms for aspirating reagents required to conduct specified assays at a reagenting location from wells  32  in an appropriate reagent cartridge  30 , the probes  60 P and  62 P subsequently being shuttled to a reagent dispensing location where reagent(s) are dispensed into reaction cuvettes  24 . A number of reagent cartridges  30  are inventoried in controlled environmental conditions inside reagent storage areas  26  and  28 ; a key factor in maintaining high assay throughput is the ability to quickly and accurately shuttle reagent cartridges  30  inside reagent storage areas  26  and  28  to reagenting locations for access by probes  60 P and  62 P. 
     Reaction cuvette load station  61  and reaction vessel load station  63  are respectively positioned proximate outer cuvette carousel  14  and inner vessel carousel  16  and are adapted to load reaction cuvettes  24  into cuvette ports  20  sideways as described later and reaction vessels  25  into vessel ports  22  using for example a translatable robotic arm  65 . In operation, used cuvettes  24  in which an assay has been finally conducted, are washed and dried in a wash station  67  like 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 cuvettes  24  unless 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 station  59  is adapted to remove unusable reaction cuvettes  24  from cuvette ports  20  again using a translatable robotic arm  65  like seen on load stations  61  and  63 . 
     A problem often encountered in the process of shuttling reagent cartridges  30  is that during use, the shuttling mechanism experiences wear adversely affecting the accuracy with which reagent cartridges  30  are presented to probes  60 P and  62 P. Another problem arises when abrupt reversals in the shuttling direction of reagent cartridges  30  are 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 cartridges  30  to be stopped at gradually changing locations. The present invention is useful in a cartridge shuttle mechanism  64  like that shown in  FIG. 5  and comprises an automated tensioner  66  to compensate for changes in length a shuttling chain or drivebelt  68  may experience during use or for changes in tension the drivebelt  68  may experience during abrupt reversals of direction so that probes  60 P and  62 P or cartridges  30  or the like may be accurately positioned at their intended location as the shuttling chain or drivebelt  68  wears. 
     In an exemplary use of automated tensioner  66  as shown in  FIG. 5 , motor  70  is controlled by computer  15  to circulate drivebelt  68  in clockwise and counter-clockwise directions, in order to position a cartridge carrier  72  having a number of reagent cartridges  30  secured thereon, only one reagent cartridge  30  being illustrated for purposes of simplicity. Carrier  72  is shown schematically secured only on one side by tie-down  74  to only one leg of drivebelt  68  so that carrier  72  is free to be driven to and from along the direction of drivebelt  68 , as indicated by double-ended arrow  76 . Consequently, cartridge  30  may be positioned as desired at a reagenting location. 
       FIG. 6A , a plan view, and  FIG. 6B , a side view, show elements of automated tensioner  66  as comprising a sprocket  78  rotatably attached to a sprocket-arm  80 , sprocket-arm  80  having a leg portion  82  slideably inserted within a closed end bore  89  (see  FIG. 7 ) formed in latching base  84 , leg portion  82  maintained in a plane via pin  81  slideable within groove  83  also formed in latching base  84 . An important feature of tensioner  66  is an elongate latch  86  and latching spring  87 , latch  86  having a latching porthole  88  (see  FIG. 7B ) formed in its central portion, leg portion  82  being slideably inserted therethrough. Elongate  86  has a gap  89  formed between prongs  91  ( FIG. 7B ) that fits over an extended ledge  85  (see  FIG. 7 ) at the back of latching base  84 . 
       FIG. 7A  is an enlarged view of latch  86  as gap  89  is positioned over ledge  85  of latching base  84 , leg portion  82  inserted through latching porthole  88  and disposed within closed bore  89  ( FIG. 7 ) also illustrating a latching spring  87  disposed between sprocket-arm  80  and latch  86 ; a compression spring  90  ( FIG. 7 ) is also disposed between leg portion  82  and the end of closed bore  89 . An important feature of the present invention is a freely hanging first end portion  86 F adapted to cooperate with a second end portion  86 S disposed in stationary contact with latching base  84 . As best seen in  FIG. 7A , due to the pressure exerted by latching spring  87  and the vertical freedom of first end portion  86 F, latch  86 , having leg portion  82  inserted through latching porthole  88 , will assume a non-perpendicular relationship with leg portion  82  so that a latching interference is created between latching porthole  88  of latch  86  and leg portion  82 . Consequently, in operation, latching spring  87  and latch  86  cooperate in a manner that allows sprocket-arm  80  to slide “away from” latching base  84  because a lower force within latching spring  87  “unlocks” or releases to allow movement between latch  86  and leg portion  82  but the latching interference between latching porthole  88  of and leg portion  82  prevents sprocket-arm  80  from moving in the opposite direction “toward” latching base  84 . A unidirectional latching effect is thereby created by the combined latching spring  87  and latch  86  due to the presence of latching porthole  88  having leg portion  82  slideably inserted therethrough as is more clearly illustrated in  FIG. 8 . 
       FIG. 7B  illustrates one embodiment of latch  86  and latching porthole  88  in which the stationary end  86 S of latch  86  is bifurcated so that a gap  89  is formed between prongs  91 , gap  89  being sized to fit over a projection  83  of latching base  84 , best seen in  FIG. 7A , thereby preventing rotation of latch  86  during use. 
     An important feature of the present invention is a compression spring  90  disposed between leg portion  82  and the end of closed bore  89  acting in a manner to constantly bias leg portion  82  within closed end bore  89  outwardly from the end of closed bore  89  causing tensioner  66  to automatically increase the separation of sprocket  78  relative to the location of motor  70  so that drivebelt  68  maintains a constant operating tension irregardless of abrupt changes in the direction of drivebelt  68  and under in-use wear that causes drivebelt  68  to 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. 9  is another application of the tensioner  66  of the present invention in a container shuttle mechanism  92  for shuttling an elongate container array  93  having a number of circular vials  94  having, for example, calibration solutions therein. Motor  95  is adapted to drive drivebelt  96  in clockwise and counter-clockwise directions, drivebelt  96  having container array  93  constrained between fingers  97  so that container array  93  is shuttled bi-directionally along double-headed arrow  96 A. As in the instance of the previously described cartridge shuttle mechanism  64 ,  FIG. 5 , the load of the weight of container array  93  and the rapid reversals in the driving direction of drivebelt  96  cause the portion of drivebelt  96  designated  96 R to alternate between having a taunt or loose tension, depending on whether the container array  93  is being shuttled towards or away from tensioner  66 , respectively. Likewise, the portion of drivebelt  96  designated  96 L will alternate between having a loose or taunt tension, depending on whether the container array  93  is being shuttled towards or away from tensioner  66 , respectively. Again, in order that multiple aspirations of calibration solutions from vials  94  be made at a accurately positioned location, it is required that drivebelt  96  be maintained at the same operating tension during use. Wear and subsequent lengthening of drivebelt  96  during use must be taken into consideration and means provided to compensate therefor. As explained previously, tensioner  66  is adapted to automatically increase the separation of sprocket  78  relative to the location of motor  95  so that drivebelt  96  maintains a constant operating tension even if drivebelt  96  is 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.