Abstract:
The present invention is directed to an automatic chemical analytical apparatus for analyzing liquid samples. In order to provide a fully automatic transport of sample tubes containing samples to be analyzed, the apparatus includes a sample processing unit, a sample transport arrangement for transporting the sample racks from a rack supply unit to a rotatable sample rack carrier in the sample processing unit and vice versa, and a computer for controlling and coordinating the operation of the sample transport arrangement and an automatic pipetting unit. The sample processing unit includes the automatic pipetting unit and the rotatable sample rack carrier that accommodates a plurality of sample racks. Each sample rack, in turn, accommodates a plurality of sample tubes.

Description:
FIELD OF THE INVENTION 
     The invention concerns an automatic chemical analytical apparatus for analyzing liquid samples. 
     BACKGROUND OF THE INVENTION 
     The invention concerns in particular an automatic chemical analytical apparatus comprising
         an automatic pipetting unit for aspirating a sample portion from a selected sample tube from an array of sample tubes located in a sample tube area, and for delivering said aspirated sample portion to a selected reaction tube from an array of reaction tubes located in a reaction tube area, each sample tube carrying on it an identification readable by a reader device,   a plurality of elongated sample racks, each of which has a length axis and is adapted to accommodate a plurality of sample tubes, each sample tube being filled with a sample, each sample rack carrying on it an identification readable by a reader device,   a rotatable sample rack carrier located in said sample tube area, said rotatable sample rack carrier being adapted to accommodate a plurality of said sample racks within a space delimited by a circumference, said sample racks being arranged along said circumference with the length axis of each of said sample racks substantially orthogonal to said circumference.       

     An analytical apparatus of this kind is described in European Patent Specification No. EP 0325101 B1. This document contains no description of any means for automatically transporting sample racks from a rack supply unit to the rotatable sample rack carrier and for positioning the sample racks on that rack carrier or for automatically removing the sample racks from that carrier and transporting them back to the rack supply unit. Therefore, according to EP 0325101 B1, the latter transport and positioning and removing operations have to be done manually. 
     In order to improve the reliability of the operation of such an analytical apparatus and generally in order to improve the overall performance of such apparatus, it is desirable to avoid as much as possible any manual operations for the transport of the sample tubes. 
     The aim of the invention is therefore to provide an analyzer of the above mentioned kind wherein the transport of the sample tubes is completely automated. 
     SUMMARY OF THE INVENTION 
     According to the invention, this aim is achieved with an automatic analytical apparatus of the above mentioned kind which comprises:
         (a) an automatic pipetting unit for aspirating a sample portion from a selected sample tube from an array of sample tubes located in a sample tube area, and for delivering said aspirated sample portion to a selected reaction tube from an array of reaction tubes located in a reaction tube area, each sample tube carrying on it an identification readable by a reader device, said automatic pipetting unit comprising a pipetting needle and means for moving said needle in 3 directions which are orthogonal to each other,   (b) a plurality of elongated sample racks each of which has a length axis and accommodates a plurality of sample tubes, each sample tube being filled with a sample, each sample rack carrying on it an identification readable by a reader device,   (c) a rotatable sample rack carrier located in said sample tube area, said rotatable sample rack carrier accommodating a plurality of said sample racks within a space delimited by a circumference, said sample racks being arranged along said circumference with the length axis of each of said sample racks substantially orthogonal to said circumference,   (d) sample transport means for transporting said sample racks from a rack input device of a rack supply unit to said rotatable sample rack carrier, and for selectively transporting said sample racks from said rotatable sample rack carrier to a rack output device of said rack supply unit, said rack input device and said rack output device each accommodating a plurality of said sample racks,   said sample transport means including means for rotating in a step-wise manner said rotatable sample rack carrier, said step-wise rotation comprising rotation intervals and rotation stop intervals, during which said sample rack carrier is at rest,   (e) said automatic pipetting unit for aspirating a portion of a sample contained in a selected sample tube located in a selected sample rack carried by said sample rack carrier during a rotation stop interval, and for delivering said aspirated sample portion to a selected reaction tube in said reaction tube area, and   (f) means for controlling and coordinating the operation of said sample transport means and said automatic pipetting unit.       

     The main advantage of an analytical apparatus according to the invention is that it includes means which provide a completely automatic transport of the sample tubes, and that these means makes it possible to attain simultaneously two aims:
         on the one hand, to provide such automatic transport at a relatively low cost and with a simple structure which facilitates service work and thereby reduces service expenses, and   on the other hand, to coordinate such automatic transport of sample tubes with the necessary sample pipetting operations, and to enable selective random-access to any of the sample tubes in the sample area for carrying out those pipetting operations.       

     Achievement of these aims contributes to optimizing/increasing the number of samples the analytical apparatus is able to analyze per unit of time. Moreover, according to the invention, the sample racks remain on the rotatable sample rack carrier as long as the analysis of any of the sample tubes contained therein is not yet completed. Thus, the sample rack carrier serves also as a buffer for sample racks, and in this way, the instant invention eliminates the need for a separate sample rack buffer. 
     Preferred embodiments of the invention are described hereinafter in further detail with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a schematic partial top view of an analyzer system according to the invention. 
         FIG. 2  shows a schematic side view of one of the racks  16  shown by  FIG. 1  and of sample tubes  12  contained therein. 
         FIG. 3  shows a schematic cross-sectional view of mechanical means for moving a sample rack  16  along transfer line  23  shown by  FIG. 1 . 
         FIG. 4  shows a schematic cross-sectional view of the mechanical means shown in  FIG. 3  in a plane perpendicular to the plane of the cross-section represented in  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As shown by  FIG. 1 , an embodiment of an automatic chemical analytical apparatus according to the invention comprises: 
     a) a sample processing unit  61  comprising:
         an automatic pipetting unit  11 , and   a rotatable sample rack carrier  19 , adapted to accommodate a plurality of said sample racks  16 , each sample rack  16  being adapted to accommodate a plurality of sample tubes  12 ,       

     b) sample transport means for transporting sample racks  16  from a rack supply unit  18  to rotatable sample rack carrier  19 , and for selectively transporting sample racks  16  from rotatable sample rack carrier  19  to rack supply unit  18 , and 
     c) means for controlling and coordinating the operation of the sample transport means and automatic pipetting unit  11 . 
     Rack supply unit  18  comprises a rack input device  17  and a rack output device  21 . In a preferred embodiment, rack supply unit  18  is located outside sample tube area  13  and comprises a stationary rack input device  17  and a stationary rack output device  21 . In a preferred embodiment, rack supply unit  18  is a separate module which is adapted to cooperate with sample processing unit  61  as described hereinafter, but which is not a part of the latter unit. For this purpose, rack supply unit  18  is so configured that sample racks  16  located therein are accessible for transport to and from sample processing unit  61 . 
     A preferred embodiment of automatic pipetting unit  11  comprises a pipetting needle and transport means for moving the pipetting needle in 3 directions X, Y, Z, which are orthogonal to each other. Such a transport system of the pipetting needle enables a random-access to samples contained in sample tubes carried by rotatable sample rack carrier  19 . 
     In a preferred embodiment, sample processing unit  61  comprises a sample tube area for receiving sample tubes to be analyzed and a reaction tube area for receiving reaction tubes where the necessary reactions of the samples with suitable reagents take place. 
     In a preferred embodiment, the sample tube area  13  includes space reserved for accommodating one or more additional sample tube racks, which are manually positioned on a stationary support. These sample tube racks are not transported by the sample transport means of an analytical apparatus according to the invention. 
     Automatic pipetting unit  11  is adapted for performing pipetting operations such as e.g. aspirating a sample portion from a selected sample tube  12  of an array of sample tubes  12  located in a sample tube area  13 , and for delivering the aspirated sample portion to a selected reaction tube  14  of an array of reaction tubes  14  located in a reaction tube area  15 . Automatic pipetting unit  11  is controlled by suitable control means in order to perform such pipetting operations successively with respect to a plurality of sample tubes, and of reaction tubes, respectively. Each sample tube  12  carries on it an identification readable by a reader device  27 . 
     Rotatable sample rack carrier  19  is located in sample tube area  13  and is adapted to accommodate a plurality of sample racks  16  within a space delimited by a circumference  22 . Sample racks  16  are arranged along circumference  22  with the length axis of each of sample racks  16  substantially orthogonal to circumference  22 , that is, the length axis of each of the sample racks  16  is radially oriented with respect to the axis of rotation of rotatable sample rack carrier  19 . 
     As can be appreciated from  FIGS. 1 and 2 , each sample rack has an elongated shape and a length axis and is adapted to accommodate a plurality of sample tubes  12  each containing a sample to be analyzed. 
     As shown by  FIG. 2 , sample tubes  12  can have different sizes, e.g. 4 ml or 7 ml, as indicated for some of the sample tubes. On the right side of  FIG. 2 , lengths in millimeters are indicated. 
     Each sample rack  16  carries on it an identification readable by a reader device  27 . In a preferred embodiment, sample tubes  12  are arranged substantially in a row along the length axis of sample rack  16 . 
     The sample transport means is adapted for transporting sample racks  16  from a rack input device  17  of rack supply unit  18  to rotatable sample rack carrier  19 , and for selectively transporting sample racks  16  from rotatable sample rack carrier  19  to a rack output device  21  of rack supply unit  18 . Rack input device  17  and rack output device  21  are each adapted to accommodate a plurality of sample racks  16 . 
     The sample transport means includes means for rotating in a step-wise manner rotatable sample rack carrier  19 . This step-wise rotation comprises rotation intervals and rotation stop intervals, during which sample rack carrier  19  is at rest. 
     In a preferred embodiment, the sample transport means are adapted for transporting sample racks  16  one-by-one from rack input device  17  to rotatable sample rack carrier  19 . 
     In a further preferred embodiment, the sample transport means are adapted for selectively transporting sample racks  16  one-by-one from rotatable sample rack carrier  19  to rack output device  21 . 
     A typical pipetting operation performed by automatic pipetting unit  11  is as follows: aspiration of a portion of a sample contained in a selected sample tube  12  located in a selected sample rack  16  carried by sample rack carrier  19  during a rotation stop interval, and delivery of the aspirated sample portion to a selected reaction tube  14  in reaction tube area  15 . 
     The control means, which control and coordinate the operation of the sample transport means and the automatic pipetting unit  11 , include e.g. a computer. The computer receives all necessary information from the different parts that constitute the analytical apparatus, and generates corresponding command signals for controlling automatic pipetting unit  11  and various parts of the sample transport means according to a suitable program. The program provides an optimized operation of the system components which participate in the transport of the sample racks  16  for a predetermined range of number of samples processed by the system by time unit. 
     In a preferred embodiment, the sample transport means include
         a transfer line  23  for transporting sample racks from rack supply unit  18  to rotatable sample rack carrier  19  and vice versa,   means for moving serially and one-by-one sample racks  16  from rack input device  17  to transfer line  23 ,   means for moving one-by-one sample racks  16  from transfer line  23  to rack output device  21 ,   means for moving one-by-one sample racks  16  from transfer line  23  to rotatable sample rack carrier  19  and vice versa,   means for rotating in a step-wise manner rotatable sample rack carrier  19 , and   a reader device  27  for reading the identification of each sample rack  16  and the identification of each sample tube  16  contained therein during their transport from the rack supply unit  18  to the rotatable sample rack carrier  19 .       

     In a preferred embodiment, the sample transport means further comprise means for moving a sample rack  25  containing at least one sample that requires urgent analysis. The rack  25  is moved from a rack input position  26  for such kind of rack to transfer line  23  in order that such sample rack  25  can be transferred to rotatable sample rack carrier  19  with high priority. 
     In a preferred embodiment, transfer line  23  is a single transfer line  23  for transporting sample racks  16  in two opposite directions, that is, from rack supply unit  18  to rotatable sample rack carrier  19  and vice versa. 
       FIGS. 3 and 4  show schematic cross-sectional views of mechanical components which form part of an embodiment of transfer line  23  described herein as an example. These components cooperate with each other for moving a sample rack  16  along transfer line  23  shown by  FIG. 1 . As can be appreciated from  FIGS. 3 and 4 , a sample rack  16  is displaced on a support plate  49 . Transport of sample rack  16  in a desired direction is achieved by means of a carriage  41  and a transport chain  45 . Carriage  41  is removably connected to sample rack  16  by means of a pin  42 . The upper part of a pin  42  of carriage  41  is removably lodged in a corresponding cavity of the bottom wall of sample rack  16 . 
     As shown by  FIG. 4 , guiding rolls  43  and a guiding rail  44  guide movement of carriage  41 . A chain guide  46  guides movement of chain  45 . A base plate  48  supports guiding rail  44  and the mechanical components which cooperate with it. 
     As shown by  FIG. 3 , a carrier bolt  51  connects carriage  41  to chain  45 . Pin  42  is fixed to carriage  41  by means of a set screw  53 . Carrier bolt  51  is fixed to carriage  41  by means of a set screw  52 . 
     The means for rotating in a step-wise manner rotatable sample rack carrier  19  include e.g. a D.C. motor and a encoder. This D.C. motor is controlled by the above-mentioned control means. 
     The means for rotating a step-wise manner rotatable sample rack carrier  19  operate in such a way that the step-wise rotation of rack carrier  19  comprises rotation intervals and rotation stop intervals, during which sample rack carrier  19  is at rest. 
     The step-wise rotation of rack carrier  19  is performed so that at the end of each rotation step a selected one of the sample racks  16  is aligned with and is ready to be transferred either to transfer line  23  for its transport to rack output device  21  of rack supply unit  18 , or to a free position  24  available to receive a sample rack  16  on sample rack carrier  19 . The free position  24  is aligned with transfer line  23  for receiving a sample rack  16  arriving to sample rack carrier  19  via transfer line  23 . For this purpose, the length axis of the end part of transfer line  23  is preferably radially oriented with respect to the axis of rotation of rotatable sample carrier  19 . 
     Each rotation step includes rotation of sample rack carrier  19  of an angle determined by the control means, e.g. an angle smaller than 180 degrees. The means for rotating rack carrier  19  are so configured that carrier  19  can be rotated in one of two opposite directions, i.e. in clock-wise direction or in a direction opposite thereto. 
     The means for moving sample racks  16  one-by-one from transfer line  23  to rotatable sample rack carrier  19  and vice versa include means for moving a selected sample rack  16  from transfer line  23  to a free position  24  on sample rack carrier  19 , during one of the rotation stop intervals, and for moving a selected sample rack  16  from its position on the sample rack carrier  19  to the transfer line  23 , during another one of the rotation stop intervals. 
     The selection of a sample rack  16  to be removed from rack carrier  19  is made by the control means on the basis of the information available on the status of the analysis operations with respect to every sample tube on carrier  19 . Every sample rack  16  remains on rack carrier  19  as long as analysis of a sample tube in that rack has not yet been completed or has to be repeated, because validity of results is deemed to be doubtful. Therefore, rack carrier  19  also performs the function of a buffer. Thus, a separate sample rack buffer is not necessary. When the analysis of all sample tubes in a sample rack  16  is completed, the control means select that rack and provide the necessary commands in order to remove that rack from rack carrier  19  as fast as possible. Therefore, every sample rack  16  remains on rack carrier  19  only during the minimum time interval required for enabling analysis of the samples on that rack. 
     The identifications carried by the sample tubes  12  and the sample racks  16  are e.g. bar-code labels readable by a bar-code reader  27 . In the embodiment shown by  FIG. 1 , bar-code reader  27  is fixedly disposed in the analyzer and is used to read the bar-code labels of each sample rack and of each sample tube contained on each vessel holder as these components pass before the bar-code reader and cross the reading path thereof during their transport on transfer line  23  from rack input device  17  to sample rack carrier  19 . 
     Numerous modifications and alternative embodiments of an analytical apparatus according to the invention will be apparent to those skilled in the art in view of the foregoing description. Accordingly, this description is to be construed as illustrative only and is for the purpose of teaching those skilled in the art the best mode of carrying out the invention. Details of the apparatus may be varied substantially without departing from the spirit of the invention and the exclusive use of all modifications which come within the scope of the appended claims is reserved.