Abstract:
A transport apparatus includes: a first transport line configured to transport a rack downstream along the transporting route; a second transport line configured to transport the rack upstream along the transporting route; and a controller including a processor and a memory that stores programs executable by the processor to: determine where to transport a post-tested rack according to whether or not retesting is necessary on any sample held in the post-tested rack; and according to a determination, instruct the transport apparatus to transport the post-tested rack selectively (i) along the first transport line either back to first sample processing unit, where the rack has been tested, or to a second sample processing unit located downstream of the first sample processing unit, or (ii) along the second transport line back from the first sample processing unit.

Description:
RELATED APPLICATIONS 
     This application claims priority under 35 U.S.C. §119 to Japanese Patent Application No. 2009-298587 filed on Dec. 28, 2009, the entire content of which is hereby incorporated by reference. 
     FIELD OF THE INVENTION 
     The present invention relates to an apparatus and a non-transitory storage medium for processing a sample, for example, measure components of the sample and prepare a smear sample thereof, and a sample container transporting apparatus which transports a sample container containing the sample to carry out the process on the sample. 
     BACKGROUND OF THE INVENTION 
     Conventionally a sample processing system provided with a plurality of sample processing apparatuses such as a multichannel blood cell analyzer or a blood smear sample preparing apparatus is known. The sample processing system transports a sample supplied by a user to these sample processing apparatuses and collects the sample already processed by the sample processing apparatuses. 
     Japanese Laid-Open Patent Publication No. 2001-74754 discloses an automatic analyzer provided with a rack setting unit where a rack holding a sample container is set, a sample feed transport line, a rack supply/collection unit which supplies the rack set in the rack setting unit to the sample feed transport line, a sample return transport line, a rack storage unit, and a plurality of analysis units. The automatic analyzer transports the rack supplied by the rack supply/collection unit in a feed direction using the sample feed transport line to analyze a target sample by any selected one of the plurality of analysis units. The post-analysis rack is transported in a return direction opposite to the feed direction by the sample return transport line and collected by the rack supply/collection unit, and then transported to and stored in the rack storage unit. The automatic analyzer disclosed in Japanese Laid-Open Patent Publication No. 2001-74754 is structurally advantageous in that the rack setting unit and the rack storage unit are provided on the same side apart from the analysis units. This structure allows the user to supply (load) and collect the sample in one place. 
     Japanese Laid-Open Patent Publication No. H06-148202 discloses an automatic analyzer which has a sample supply unit where a sample rack is set, a transport line used to transport the sample rack supplied at a predetermined transport start position by the sample supply unit, a reaction unit which suctions a given volume of the sample from a sample container held in the sample rack transported to a predetermined suctioning position to perform a predefined test to the suctioned sample, return lines used to return the sample rack from which the samples are already suctioned, a sorting mechanism which sorts the sample rack to one of the return lines, a return mechanism which returns the sample rack returned by the return line selectively to the transport start position, and a rack storage unit which stores therein the test-completed sample rack. In the automatic analyzer disclosed in Japanese Laid-Open Patent Publication No. H06-148202, the sample supply unit and the rack storage unit are provided on the same side apart from the reaction unit, and the sample rack to be retested is transported again to the transport start position by the return mechanism, whereas the sample racks which are not to be tested are transported to the rack storage unit. 
     In the automatic analyzer disclosed in the Japanese Laid-Open Patent Publication No. 2001-74754, if the sample held in the rack supplied from the rack supply/collection unit is analyzed by at least two analysis units, the sample is suctioned at the sample suctioning position in one of the analysis units to be analyzed there, and then further transported to the sample suctioning position of the other analysis unit to be suctioned and analyzed there. However, no regard is given to retesting (reanalysis) in the automatic analyzer. 
     In the automatic analyzer disclosed in Japanese Laid-Open Patent Publication No. H06-148202, the sample rack holding the sample to be retested is transported to the exit of the transport line similarly to the sample rack which holds only the samples which need not be retested, and then transported by the return line in a direction opposite to the transport direction of the transport line back to the transport start position again. Thus, the sample rack has to travel a long transport path, which is a bottleneck in improving the efficiency of retest. In the case where a sample is currently suctioned from any other sample rack by the reaction unit on the downstream side of the transport direction, for example, it is necessary to suspend the transport of the sample rack to be retested until the suctioning is over, which causes clogging on the transport path. Whenever the traffic on the transport path is thus clogged, the retesting efficiency is significantly deteriorated. 
     SUMMARY OF THE INVENTION 
     The scope of the present invention is defined solely by the appended claims, and is not affected to any degree by the statements within this summary. 
     A first aspect of the present invention is a sample processing apparatus comprising: a plurality of sample processing units arranged along a line of transporting route, the plurality of sample processing units comprising a sample processing unit configured to test a sample held in a rack and issue a test result on the sample; a sample feeding unit located upstream of the plurality of sample processing units along the transporting route and configured to store pre-tested racks waiting to be tested; a collecting unit located upstream of the plurality of sample processing units along the transporting route and configured to store post-tested racks; a transport apparatus comprising a first transport line configured to transport the rack downstream along the transporting route from the sample feeding unit and a second transport line configured to transport the rack upstream along the transporting route toward the collecting unit; and a controller comprising a processor and a memory that stores programs executable by the processor to: determine where to transport the post-tested rack according to whether or not retesting is necessary on any sample held in the post-tested rack; and according to a determination, instruct the transport apparatus to transport the post-tested rack selectively (i) along the first transport line either back to a first sample processing unit, where the sample in the rack has been tested, or to a second sample processing unit located downstream of the first sample processing unit, or (ii) along the second transport line back to the collecting unit from the first sample processing unit. 
     A second aspect of the present invention is a transport apparatus for transporting racks with samples along a transporting route along which a plurality of sample processing units are arranged, comprising: a first transport line configured to transport a rack downstream along the transporting route; a second transport line configured to transport the rack upstream along the transporting route; and a controller comprising a processor and a memory that stores programs executable by the processor to: determine where to transport a post-tested rack according to whether or not retesting is necessary on any sample held in the post-tested rack; and according to a determination, instruct the transport apparatus to transport the post-tested rack selectively (i) along the first transport line either back to first sample processing unit, where the rack has been tested, or to a second sample processing unit located downstream of the first sample processing unit, or (ii) along the second transport line back from the first sample processing unit. 
     A third aspect of the present invention is at least one non-transitory storage medium which stores programs executable collectively by at least one processor to: transport a pre-tested rack to a first sample processing unit for testing which is selected among a plurality of sample processing units arranged along a transporting route; receive a test result for the rack from the first sample processing unit; based on the test result, determine whether or not retesting is necessary on any sample held in the post-tested rack; if it is determined that retesting is necessary, transport the post-tested rack either back to the first sample processing unit or to a second testing unit located downstream of the first testing unit along the transporting route; and if it is determined that retesting is not necessary, transport the post-tested rack back along the transporting route from the first sample processing unit. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic plan view of an overall structure of a sample processing system according to an embodiment of the present invention; 
         FIG. 2  is a perspective view of an external appearance of a sample container; 
         FIG. 3  is a perspective view of an external appearance of a sample rack; 
         FIG. 4  is a plan view illustrating a structure of a sample transport unit used in a blood analysis apparatus according to the embodiment; 
         FIG. 5  is a plan view illustrating a structure of a sample transport unit used in a smear sample preparing apparatus according to the embodiment; 
         FIG. 6  is a block diagram illustrating a structure of a measurement unit provided in the blood analysis apparatus according to the embodiment; 
         FIG. 7  is a block diagram illustrating a structure of an information processing unit provided in the blood analysis apparatus according to the embodiment; 
         FIG. 8  is a block diagram schematically illustrating a structure of the smear sample preparing apparatus according to the embodiment; 
         FIG. 9  is a block diagram illustrating a structure of a system controller according to the embodiment; 
         FIG. 10  is a flow chart illustrating processing steps in setting a transport mode carried out by the system controller according to the embodiment; 
         FIG. 11  is a schematic illustration of measurement orders of pre-measurement samples stored in a test information management apparatus; 
         FIG. 12  is a schematic illustration of measurement orders of post-measurement samples stored in the test information management apparatus; 
         FIG. 13  is a schematic illustration of measurement orders of post-analysis samples stored in the test information management apparatus; 
         FIG. 14  is a flow chart illustrating transport control processing steps carried out by the sample transport unit in a first transport mode; 
         FIG. 15  is a flow chart illustrating transport instruction processing steps carried out by the system controller in the first transport mode; and 
         FIG. 16  is a flow chart illustrating transport control processing steps carried out by the information processing unit in a second transport mode. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     An embodiment of the present invention is described below referring to the drawings. 
     [Structure of Sample Processing System] 
       FIG. 1  is a schematic plan view of an overall structure of a sample processing system according to an embodiment of the present invention. As illustrated in  FIG. 1 , a sample processing system  1  is provided with a sample loading and collection apparatus  2 , a sample transport apparatus  3 , a blood cell analysis apparatus  5 , a smear sample preparing apparatus  6 , and a system controller  8 . The sample processing system  1  according to the present embodiment is connected to a test information management apparatus  9  through a communication network to allow communication with the test information management apparatus  9 . 
     The sample transport apparatus  3  has sample transport units  3   a ,  3   b ,  3   c , and  4 , and these sample transport units  3   a ,  3   b ,  3   c , and  4  are serially connected to one another so as to linearly extend in lateral directions of the drawing. The blood cell analysis apparatus  5  has three measurement units  51 ,  52 , and  53 , and an information processing unit  54 . The measurement unit  51  is provided behind the sample transport unit  3   a , the measurement unit  52  is provided behind the sample transport unit  3   b , and the measurement unit  53  is provided behind the sample transport unit  3   c . The smear sample preparing apparatus  6  is provided behind the sample transport unit  4 . 
     The sample transport units  3   a ,  3   b ,  3   c , and  4  are respectively provided with supply lines  3   a S,  3   b S,  3   c S, and  4 S (first transport line) used as transport paths to transport a sample rack so that samples housed therein are supplied to the measurement units  51 ,  52 , and  53  and the smear sample preparing apparatus  6  (sample processing unit), which are all laterally extending. The sample transport apparatus  3  is further provided with return lines  3   a R,  3   b R,  3   c R, and  4 R (second transport path) used as transport paths to transport the sample rack rightward in the drawing to be collected. The supply line  3   a S includes a measurement line  3   a M (fetching line) laterally extending, and a skipping line  3   a F which transports the sample rack holding a plurality of samples leftward in the drawing. The other supply lines  3   b S,  3   c S and  4 S similarly have measurement lines  3   b M and  3   c M, a processing line  4 M, skipping lines  3   b F and  3   c F and a transport line  4 F. The measurement lines  3   a M,  3   b M, and  3   c M and the processing line  4 M are the transport paths for transporting the sample rack so that the measurement units  51 ,  52 , and  53  and the smear sample preparing apparatus  6  can fetch the samples housed therein. The measurement lines  3   a M,  3   b M, and  3   c M and the processing line  4 M are independent from one another with no connection therebetween. The skipping lines  3   a F,  3   b F, and  3   c F and the transport line  4 F are the transport paths for transporting the sample rack directly toward the downstream side of the transport direction while skipping the sample fetch by any of the measurement units  51 ,  52 , and  53  and the smear sample preparing apparatus  6 . Of the skipping lines  3   a F,  3   b F, and  3   c F and the transport line  4 F, the adjacent lines are connected to each other. All of these lines are linearly aligned. 
     Between the skipping lines  3   a F,  3   b F,  3   c F and the transport line  4 F, and the measurement lines  3   a M,  3   b M, and  3   c M and the processing line  4 M, there are pre-analysis rack holding sections  33  and  43  (first relay sections) serving as transport paths for receiving the sample rack from the skipping lines  3   a F,  3   b F,  3   c F and the transport line  4 F and transporting the received sample rack to starting points of the measurement lines  3   a M,  3   b M, and  3   c M and the processing line  4 M, and also as regions for holding the sampler rack, and post-analysis rack holding sections  34  and  44  (second relay sections) serving as transport paths for receiving the sample rack from terminal points of the measurement lines  3   a M,  3   b M, and  3   c M and the processing line  4 M and transporting the received sample rack to the skipping lines  3   a F,  3   b F, and  3   c F and the transport line  4 F or the return lines  3   a R,  3   b R,  3   c R, and  4 R, and also as regions for holding the sample rack. The pre-analysis analysis rack holding sections  33  and  43 , and the post-analysis analysis rack holding sections  34  and  44  (second relay sections) also constitute a part of the supply lines  3   a S,  3   b S,  3   c S, and  4 S. 
     The sample loading and collection apparatus  2  where the sample rack is loaded by a user is connected to the right end of the sample transport apparatus  3 . The sample rack discharged from the sample loading and collection apparatus  2  is transported along the skipping line  3   a F,  3   b F,  3   c F or  4 F of the sample transport apparatus  3 . The sample rack transported along the skipping line  3   a F,  3   b F,  3   c F or  4 F passes through the pre-analysis rack holding section  33  or  43  in the sample transport unit  3   a ,  3   b ,  3   c , or  4  corresponding to a transport destination which is the measurement unit  51 ,  52 , or  53  or the smear sample preparing apparatus  6 . The sample rack is then transported to the measurement line  3   a M,  3   b M,  3   c M or the processing line  4 M. The sample rack is transported on the measurement line or the processing line, and then supplied to the measurement unit  51 ,  52 ,  53  or the smear sample preparing apparatus  6  serving as the destination. After the sample is supplied to the measurement unit  51 ,  52 ,  53  or the smear sample preparing apparatus  6 , the sample rack travels along the measurement line  3   a M,  3   b M,  3   c M or the processing line  4 M and passes through the post-analysis rack holding section  34  or  44 . The sample rack is then transported to the return line  3   a R,  3   b R,  3   c R, or  4 R, and further transported on the return line rightward to be collected by the sample loading and collection apparatus  2 . 
       FIG. 2  is a perspective view of an external appearance of a sample container.  FIG. 3  is a perspective view of an external appearance of a sample rack. As illustrated in  FIG. 2 , a sample container T has a tubular shape, and an upper end thereof is open. The sample container contains therein blood collected from a patient as a sample, and its upper-end opening is sealed with a cap portion CP. The sample container T is made of optically transparent glass or synthetic resin so that the blood sample inside is visible. A barcode label BL is affixed to a side surface of the sample container T. The barcode label BL has a barcode (sample barcode) representing a sample ID printed thereon. A sample rack L can hold 10 sample containers T in an aligned manner. The sample rack L holds the sample containers T perpendicularly (upright position). A rack barcode label (not illustrated in the drawings) is affixed to a front surface of the sample rack L. The rack barcode label has a barcode (rack barcode) representing a rack ID printed thereon. 
     Hereinafter, the structural elements of the sample processing system  1  are described in detail. 
     &lt;Structure of Sample Loading and Collection Apparatus  2 &gt; 
     As illustrated in  FIG. 1 , the sample loading and collection apparatus  2  includes a sample loading unit  21 , a pre-processing unit  22 , and a sample collection unit  23 . The sample loading and collection apparatus  2  can set therein a sample rack holding a plurality of sample containers. 
     The sample loading unit  21  can load therein the sample rack L supplied by a user. The sample loading unit  21  can transfer the sample rack L loaded by the user to the rearmost side of the sample loading unit  21  (Y 1  direction) and transport the sample rack L to the left side of the sample loading unit  21  (to the side of the pre-processing unit  22 ). 
     The pre-processing unit  22  is connected to the left side of the sample loading unit  21  to receive the sample rack L dispatched from the sample loading unit  21 . The pre-processing unit  22  has a barcode readout device  22   b . The barcode readout device  22   b  can read out the sample ID from the barcode label BL of the sample container T set in the sample rack L and also read out the rack ID from the rack barcode label of the sample rack L. The pre-processing unit  22  can transfer the sample rack L already barcode-read by the barcode readout device  22   b  to the front side of the pre-processing unit  22  (Y 2  direction) and thereafter transport the sample rack L to the left side of the pre-processing unit  22  (to the side of the sample transport unit  3   a ). In the vicinity of a rack delivering position between the pre-processing unit  22  and the sample transport unit  3   a , a dedicated barcode readout device  222   a  for reading out the rack barcode of the sample rack L is provided. The sample rack L dispatched from the pre-processing unit  22  is guided to the skipping line  3   a F of the sample transport apparatus  3 . The pre-processing unit  22  has a controller  22   a  including such structural components as a CPU and a memory. The controller  22   a  controls the mechanism of the pre-processing unit  22 . 
     The sample collection unit  23  is provided on the right side of the sample loading unit  21  and has a structure similar to that of the sample loading unit  21 . The sample collection unit  23  collects the sample rack L transported thereto by the return line  3   a R, or the collection line  223 ,  217 ,  237 . 
     [Structure of Sample Transport Apparatus  3 ] 
     The structural characteristic of the sample transport apparatus  3  is described below. As illustrated in  FIG. 1 , the sample processing system  1  has the sample transport apparatus  3  including four sample transport units  3   a ,  3   b ,  3   c , and  4 . The sampler transport units  3   a ,  3   b , and  3   c  are respectively provided on the front side of three measurement units  51 ,  52 , and  53  of the blood cell analysis apparatus  5 . Of the sample transport units  3   a ,  3   b , and  3   c , the adjacent sample transport units are connected to each other so that the sample rack L can be passed and received therebetween. The rightmost sample transport unit  3   a  is connected to the sample loading and collection apparatus  2  to receive the sample rack L transported from the sample loading and collection apparatus  2  and send the sample rack L back to the sample loading and collection apparatus  2 . 
       FIG. 4  is a plan view illustrating a structure of the sample transport unit  3   a . Hereinafter, the sample transport unit  3   a  disposed on the front side of the measurement unit  51  is described. The description given below is also applied to structures of the other sample transport units  3   b  and  3   c  disposed on the front side of the measurement units  52  and  53 . As illustrated in  FIG. 4 , the sample transport unit  3   a  has a transport mechanism  31 , and a controller  32  which controls the transport mechanism  31 . The transport mechanism  31  has a pre-analysis rack holding section  33 , a post-analysis rack holding section  34 , a measurement line  3   a M (fetching line) which horizontally transfers the sample rack L in the direction of arrow X in the drawing and transports the sample rack L received from the pre-analysis rack holding section  33  to the post-analysis rack holding section  34  in order to supply the sample to the measurement unit  51 , a skipping line  3   a F which accepts the sample rack L from the apparatus on the transport upstream side (sample loading and collection apparatus  2 ) and transports the sample rack L to the apparatus on the transport downstream side (sample transport unit  3   b ) without supplying the samples contained in the sample rack L to the measurement unit  51 , and a return line  3   a R (second transport line) which accepts the sample rack L from the apparatus on the transport downstream side (sample transport unit  3   b ) and transports the sample rack L to the apparatus on the transport upstream side (sample loading and collection apparatus  2 ) without supplying the samples contained in the sample rack L to the measurement unit  51 . 
     The skipping line  3   a F has a belt conveyer  321  having an annular belt  321   a  and a stepping motor  321   b . The belt conveyer  321  rotates the belt  321   a  in the direction of arrow X 1  using a driving force of the stepping motor  321   b  to thereby transfer the sample rack L disposed on the belt  321   a  in the direction of X 1 . The skipping lines  3   a F,  3   b F, and  3   c F of the sample transport units  3   a ,  3   b , and  3   c , and the transport line  4 F of the sample transport unit  4  which will be described later each similarly includes a belt conveyer, and the sample rack L can be transported by the respective belt conveyers. 
     The return line  3   a R in parallel with the skipping line  3   a F is provided away from the skipping line  3   a F by a given distance in the forward direction. The return line  3   a R has a belt conveyer  331  having an annular belt  331   a  and a stepping motor  331   b . The belt conveyer  331  rotates the belt  331   a  in the direction of arrow X 2  using a driving force of the stepping motor  331   b  to thereby transfer the sample rack L disposed on the belt  331   a  in the direction of X 2 . The return lines  3   a R,  3   b R, and  3   c R of the sample transport units  3   a ,  3   b , and  3   c , and the return line  4 R of the sample transport unit  4  which will be described later each similarly includes a belt conveyer, and the sample rack L can be transported by the respective belt conveyers. 
     On the front side of the pre-analysis rack holding section  33 , a rack delivering portion  322  is provided between the skipping line  3   a F and the return line  3   a R so as to face the pre-analysis rack holding section  33 . The rack delivering portion  322  is horizontally transferred in a linear manner in the direction of Y 1  (rearward) by a driving force of the stepping motor  322   a . Accordingly, when the sample rack L is transported by the skipping line  3   a F from the apparatus on the upstream side of the transport direction and arrives at a position  323  on the skipping line  3   a F between the pre-analysis rack holding section  33  and the rack delivering portion  322  (hereinafter, called “pre-analysis rack delivering position”), the rack delivering portion  322  is transferred to the side of the pre-analysis rack holding section  33  to push the sample rack L into the pre-analysis rack holding section  33 . The sample transport unit  3   a  is equipped with a rack sensor  373  which detects the sample rack L that arrived at the pre-analysis rack delivering position  323 . The rack sensor  373  has a photoemitter  373   a  and a photoreceiver  373   b.    
     The pre-analysis rack holding section  33  has a rectangular shape in planar view. The lateral length of the pre-analysis rack holding section  33  is slightly larger than that of the sample rack L. The width of the pre-analysis rack holding section  33  (length in front-back direction) is slightly larger than twice the width of the sample rack L. The pre-analysis rack holding section  33  is formed in a height lower than any other surface around it, and the pre-analysis sample rack L is disposed on an upper surface thereof. According to the structure, the pre-analysis rack holding section  33  can hold two sample racks L at a time. The pre-analysis rack holding section  33  is continuous to the skipping line  3   a F so that the sample rack L is delivered thereto from the skipping line  3   a F by the rack delivering portion  322 . In the vicinity of the pre-analysis rack holding section  33 , a rack sensor  371  is mounted, and the sample rack L placed in the pre-analysis rack holding section  33  is detected by the rack sensor  371 . The rack sensor  371  is an optical sensor, having a photoemitter  371   a  and a photoreceiver  371   b . The photoemitter  371   a  is provided on a lateral side of the pre-analysis rack holding section  33 , while the photoreceiver  371   b  is provided on a straight line which traverses the pre-analysis rack holding section  33  slantwise toward its front side from the photoemitter  371   a . The photoemitter  371   a  is positioned so that light is emitted diagonally forward, and the photoreceiver  371   b  is positioned to be able to receive the emitted light. Therefore, the sample rack L transported from the skipping line  3   a F is placed in the pre-analysis rack holding section  33 , and the sample rack L thus placed blocks the light emitted from the photoemitter  371   a  to lower the light reception of the photoreceiver  371   b . As a result, the sample rack L can be detected by the rack sensor  371 . The pre-analysis rack holding section  33  has rack senders  33   b  protruding inward from the both surfaces thereof. When the sample rack L is detected by the rack sensor  371 , the rack senders  33   b  shift rearward (direction toward the measurement line  3   a M) to be engaged with the sample rack L, and thereby transport the sample rack L rearward. The rack senders  33   b  can be driven by a stepping motor  33   c  provided below the pre-analysis rack holding section  33 . 
     On the transport path where the sample rack L is transported by the measurement line  3   a M, there are a sample container detecting position  35   a  at which the sample container is detected by a sample container sensor  38 , and a sample supply position  35   c  (sample fetching position) at which the sample is supplied to the measurement unit  51  of the blood cell analysis apparatus  5 . The measurement line  3   a M can be used to transport the sample to the sample supply position  35   c  by way of the sample container detecting position  35   a . The sample supply position  35   c  is a position provided on the downstream side of the transport direction away from the sample container detecting position  35   a  by a dimension equal to one sample. When the sample is transported to the sample supply position  35   c  by the measurement line  3   a M, a hand portion of the measurement unit  51  of the blood cell analysis apparatus  5 , which will be described later, grips the sample container T containing the sample to take the sample container T out of the sample rack L. Then, the sample is suctioned from the sample container T and supplied to the measurement unit  51 . After the sample container is transported to the sample supply position  35   c  along the measurement line  3   a M, the sample transport unit  3   a  temporarily suspends the transport of the sample rack L until the sample container T is returned to the sample rack L after the supply of the sample is finished. 
     The measurement line  3   a M includes a belt conveyer  353  having a first belt  351  and a second belt  352  which independently operate, a stepping motor  351   e  which drives the first belt  351 , and a stepping motor  352   e  which drives the second belt  352 . 
     A rack delivering section  39 , which will be described later, is provided so as to face the post-analysis rack holding section  34  with the measurement line  3   a M interposed therebetween. The rack delivering section  39  is horizontally moved in the direction of arrow Y in a linear manner by a driving force of a stepping motor  39   a . Accordingly, when the sample rack L is transported to a position  391  between the post-analysis rack holding section  34  and the rack delivering section  39  (hereinafter, called “post-analysis rack delivering position”), the rack delivering section  39  is moved to the side of the post-analysis rack holding section  34  to push the sample rack L into the post-analysis rack holding section  34 . As described, the analysis-completed sample rack L is transported from the measurement line  3   a M to the post-analysis rack holding section  34 . The sample transport unit  3   a  is provided with a rack sensor  374  which detects the sample rack which arrived at the post-analysis rack delivering position  391 . The rack sensor  374  has a photoemitter  374   a  and a photoreceiver  374   b.    
     The post-analysis rack holding section  34  has a rectangular shape in planar view. The lateral length of the post-analysis rack holding section  34  is slightly larger than that of the sample rack L, and its width (length in front-back direction) is slightly larger than twice the width of the sample rack L. The post-analysis rack holding section  34  is formed in a height lower than any other surface around it, and the analysis-completed sample rack L is disposed on an upper surface thereof. According to the structure, the post-analysis rack holding section  34  can hold two sample racks L at a time. The post-analysis rack holding section  34  is continuous to the measurement line  3   a M so that the sample rack L is delivered thereto from the measurement line  3   a M by the rack delivering section  39 . In the vicinity of the post-analysis rack holding section  34 , a rack sensor  372  is mounted, and the sample rack L placed in the post-analysis rack holding section  34  is detected by the rack sensor  372 . The rack sensor  372  is an optical sensor, having a photoemitter  372   a  and a photoreceiver  372   b . The photoemitter  372   a  is provided on a lateral side of the post-analysis rack holding section  34 , while the photoreceiver  372   b  is provided on a straight line which traverses the post-analysis rack holding section  34  slantwise toward its front side from the photoemitter  372   a . The photoemitter  372   a  is positioned so that light is emitted diagonally forward, and the photoreceiver  372   b  is positioned to be able to receive the emitted light. Therefore, the sample rack L transported from the rack delivering section  39  is placed in the post-analysis rack holding section  34 , and the sample rack L thus placed blocks the light emitted from the photoemitter  372   a  to lower the light reception level of the photoreceiver  372   b . As a result, the sample rack L can be detected by the rack sensor  372 . The post-analysis rack holding section  34  has rack senders  34   b  protruding inward from the both surfaces thereof. When the sample rack L is detected by the rack sensor  372 , the rack senders  34   b  shift forward (direction toward the skipping line  3   a F and return line  3   a R) to be engaged with the sample rack L, and thereby transport the sample rack L forward. The rack senders  34   b  can be driven by a stepping motor  34   c  provided below the post-analysis rack holding section  34 . Further, the post-analysis rack holding section  34  is continuous to the skipping line  3   a F and the return line  3   a R. According to the structure, the rack senders  34   b  can transport the sample rack L placed in the post-analysis rack holding section  34  to one of the skipping line  3   a F and the return line  3   a R. The rack senders  34   b  transport the sample rack L placed in the post-analysis rack holding section  34  to a position  3 T (hereinafter, called “rack transport position”) on the skipping line  3   a F on the front side of the post-analysis rack holding section  34 . The rack senders  34   b  can transfer the sample rack L placed in the post-analysis rack holding section  34  to the return line  3   a R by way of the rack transport position  3 T. 
     The transport mechanism  31  structurally characterized as described so far is mostly controlled by the controller  32 . The controller  32  includes such structural elements as CPU, ROM and RAM (not illustrated in the drawing). The controller  32  can run a control program of the transport mechanism  31  stored in the ROM on the CPU. The controller  32  is equipped with an Ethernet (registered trademark) interface and connected to the information processing unit  54  and the system controller  8  via LAN. 
     Of the structural elements of the transport mechanism  31 , the rack senders  33   b , the belt conveyer  353  constituting the measurement line  3   a M, and the rack delivering section  39  are controlled by the information processing unit  54  of the blood cell analysis apparatus  5 . The other structural elements of the transport mechanism  31  are controlled by the controller  32 . 
     According to the structure thus far described, the sample transport unit  3   a  ( 3   b ,  3   c ) can transport the sample rack L transported from the sample loading and collection apparatus  2  to the pre-analysis rack delivering position  323  along the skipping line  3   a F, transport the sample rack L to the pre-analysis rack holding section  33  using the rack delivering portion  322 , and then transfer the sample rack L from the pre-analysis rack holding section  33  to the measurement line  3   a M and further transport the sample rack L on the measurement line  3   a M to finally supply the sample to the measurement unit  51  ( 52 ,  53 ). The sample rack L containing the sample that has finished the suction is transported to the post-analysis rack delivering position  391  by the measurement line  3   a M, and then transported to the post-analysis rack holding section  34  by the rack delivering section  39 . The sample rack L held by the post-analysis rack holding section  34  is transported to the return line  3   a R in the case where none of the samples held therein needs retesting, and then transported to the apparatus (sample loading and collection apparatus  2 ) in the former stage (upstream side of the transport direction) along the return line  3   a R. On the other hand, the sample rack L holding any sample which needs to be retested is transported to one of the measurement units  51 ,  52 , and  53  and the smear sample preparing apparatus  6  along the supply line  3   a S,  3   b S,  3   c S, or  4 S to be retested (reprocessed) by the apparatus of the transport destination. 
     When the sample rack L holding any sample to be processed by the measurement unit  52  or  53  on the transport downstream side or the smear sample preparing apparatus  6  is received from the apparatus in the former stage by the sample transport unit  3 , the received sample rack L is transported along the skipping line  3   a F in the direction of arrow X 1  to be directly transported to the sample transport unit  3   b  in the latter stage. When the sample rack L to be collected by the sample loading and collection apparatus  2  is received from the sample transport unit  3   b  in the latter stage by the sample transport unit  3   a , the received sample rack L is transported along the return line  3   a R of the sample transport unit  3   a  in the direction of arrow X 2  to be directly transported to the sample loading and collection apparatus  2  in the former stage. 
     As illustrated in  FIG. 1 , the sample transport unit  4  is disposed on the front side of the smear sample preparing apparatus  6 . Of the three sample transport units  3   a ,  3   b , and  3   c , the sample transport unit  3   c  at the farthest end of the transport downstream side (left side in the drawing) is connected to the right end of the sample transport unit  4 . 
       FIG. 5  is a plan view illustrating a structure of the sample transport unit  4 . The sample transport unit  4  has a transport mechanism  41  which transports a sample, and a controller  42  which controls the transport mechanism  41 . The transport mechanism  41  has a pre-process rack holding section  43  capable of temporarily holding the sample rack L which holds the sample containers T containing the samples from which no smear sample is yet prepared, a post-process rack holding section  44  capable of temporarily holding the sample rack L which holds the sample containers T from which the samples have been suctioned by the smear sample preparing apparatus  6 , a processing line  4 M which horizontally moves the sample rack L in a linear manner in the direction of X 1  to supply the sample rack L received from the pre-process rack holding section  43  to the post-process rack holding section  44  in order to supply the sample to the smear sample preparing apparatus  6 , a transport line  4 F which accepts the sample rack L from the sample transport unit  3   c  on the transport upstream side and transports the sample rack L in the direction of X 1 , and a return line  4 R which transports the sample rack L to the sample transport unit  3   c  on the transport upstream side in order to collect the sample rack L for which the smear sample preparation is completed by the sample loading and collection apparatus  2 . The structural elements of the sample transport apparatus  4  have dimensions, shapes and positions different to those of the sample transport units  3   a ,  3   b , and  3   c . However, they are functionally similar to the sample transport units  3   a ,  3   b , and  3   c . Therefore, description of these structural elements is omitted. 
     The sample transport unit  4  accepts the sample rack L transported from the sample transport unit  3   c  on the upstream side using the transport line  4 F, transfers the sample rack L to the pre-process rack holding section  43  using a rack delivering section not illustrated in the drawing, and then transports the sample rack L from the pre-process rack holding section  43  to the processing line  4 M to transport the sample rack L along the processing line  4 M so that the sample rack L is finally transported to the smear sample preparing apparatus  6 . The sample rack L containing the sample that has finished the suction is transported by the processing line  4 M to the post-process rack holding section  44  by a rack delivering section not illustrated in the drawing. The sample rack L held by the post-process rack holding section  44  is transferred to the return line  4 R, and transported along the return line  4 R to the sample transport unit  3   c  in the former stage (upstream side of the transport direction). 
     A left-end position of the transport line  4 F of the sample transport unit  4 , in other words, a position on the front side of the post-process rack holding section  44  is a terminal position  3 E of the supply lines  3   a S,  3   b S,  3   c S and  4 S (first transport line). The sample rack L which holds any sample for which the smear sample preparation is necessary is transported along the supply line  4 S of the sample transport unit  4 , and the sample is supplied to the smear sample preparing apparatus  6 . After that, the sample rack L passes through the post-analysis rack holding section  44  by way of the terminal point  3 E. Then, the sample rack L is transferred to the return line  4 R and transported along the return line  4 R in the direction of X 2  to be collected by the sample collection unit  23 . 
     [Structure of Blood Cell Analysis Apparatus  5 ] 
     The blood cell analysis apparatus  5  is a multichannel blood cell analysis apparatus which uses optical flow cytometry. A side scattered light intensity and a fluorescence intensity, for example, of blood cells included in blood collected as a sample are obtained to classify the blood cells included in the sample into different types based on the obtained light intensities. Further, the blood cells of different types are separately counted, and a scattergram in which the blood cells thus classified are shown in different colors is created and displayed. The blood cell analysis apparatus  5  has measurement units  51 ,  52 , and  53  which measure blood collected as a sample, and an information processing unit  54  which processes measurement data outputted from the measurement units  51 ,  52 , and  53  and displays an analysis result of the blood sample. 
     As illustrated in  FIG. 1 , the blood cell analysis apparatus  5  has three measurement units  51 ,  52 , and  53  and one information processing unit  54 . The information processing unit  54  is connected to the three measurement units  51 ,  52 , and  53  to allow communication therebetween. The information processing unit  54  can control the operations of the three measurement units  51 ,  52 , and  53 . The information processing unit  54  is also connected to the three sample transport units  3   a ,  3   b , and  3   c  disposed on the front side of the three measurement units  51 ,  52 , and  53  so as to communicate therewith. 
       FIG. 6  is a block diagram illustrating a structure of the measurement unit  51 . As illustrated in  FIG. 6 , the measurement unit  51  has a sample suctioning section  511  which suctions the blood sample from the sample container (blood collection tube) T, a specimen preparing section  512  which prepares a measurement specimen from the blood suctioned by the sample suctioning section  511 , and a detecting section  513  which detects blood cells in the measurement specimen prepared by the specimen preparing section  512 . The measurement unit  51  further has a fetching port (not illustrated in the drawing) through which the sample container T held in the sample rack L transported on the measurement line  3   a M of the sample transport unit  3   a  is fetched into the measurement unit  51 , and a sample container transport section  515  which fetches the sample container T into the measurement unit  51  from the sample rack L and transports the fetched sample container T to a suctioning position where the sample is suctioned by the sample suctioning section  511 . 
     The detecting section  513  can detect RBC (red blood cells) and PLT (platelets) by employing sheath flow DC detection. The detecting section  513  can also detect HGB (hemoglobin) by employing SLS-hemoglobin method and detect WBC (white blood cells) by employing flow cytometry in which a semiconductor laser is used. The RBC, PLT, HGB, and WBC are measured when CBC (complete blood count) is requested. 
     The measurement unit  51  can classify the white blood cells into five categories (measurement item DIFF). More specifically, the detecting section  513  of the measurement unit  51  can detect WBC (white blood cell), NEUT (neutronphile), LYMPH (lymphocyte), EO (eosinocyte), BASO (basocyte), and MONO (monocyte) by employing flow cytometry in which a semiconductor laser is used. 
     The detecting section  513  of the measurement unit  51  can measure reticulocyte (RET) as well. To measure RET, a measurement specimen is prepared by mixing the sample with a reagent for RET measurement, and the prepared measurement specimen is supplied to an optical detector of the detecting section  513  provided to detect WBC/DIFF (five categories of WBC). 
     The measurement units  52  and  53  are structurally similar to the measurement unit  51  and can measure CBC, DIFF, and RET similarly to the measurement unit  51 . 
     The sample container transport section  515  has a hand portion  515   a  which can grip the sample container T. The sample container transport section  515  can move the hand portion  515   a  upward and downward, and also forward and backward (Y direction). The hand portion  515   a  takes the sample container T housed in the sample rack L and placed at the supply position  35   c  out of the sample rack L and sets the sample container T in a recess of a sample container setter  515   b . The sample container setter  515   b  is then moved to the suctioning position. 
     Hereinafter, a structure of the information processing unit  54  is described. The information processing unit  54  includes a computer.  FIG. 7  is a block diagram illustrating the structure of the information processing unit  54 . The information processing unit  54  is run by a computer  54   a . As illustrated in  FIG. 7 , the computer  54   a  has a main body  541 , an image display device  542 , and an input device  543 . The main body  541  has a CPU  541   a , a ROM  541   b , a RAM  541   c , a hard disc  541   d , a readout device  541   e , an input/output interface  541   f , a communication interface  541   g , and an image output interface  541   h . The CPU  541   a , ROM  541   b , RAM  541   c , hard disc  541   d , readout device  541   e , input/output interface  541   f , communication interface  541   g , and image output interface  541   h  are connected to one another by a bus  541   j.    
     The readout device  541   e  can read out a computer program  544   a  which makes the computer function as the information processing unit  54  from a transportable recording medium  544 , and install the computer program  544   a  in the hard disc  541   d.    
     [Structure of Smear Sample Preparing Apparatus  6 ] 
     To prepare a smear sample, the smear sample preparing apparatus  6  suctions the blood sample and drops the suctioned blood on a glass slide, spreads the dropped sample on the glass slide very thin, dries the spread sample, and then supplies a staining liquid on the glass slide to stain the blood thereon. 
       FIG. 8  is a block diagram illustrating a schematic structure of the smear sample preparing apparatus  6 . As illustrated in  FIG. 8 , the smear sample preparing apparatus  6  has a sample dispensing unit  61 , a smearing unit  62 , a glass slide transport unit  63 , a staining unit  64 , and a controller  65 . 
     The sample dispensing unit  61  has a suctioning tube (not illustrated in the drawing). The sample dispensing unit  61  penetrates the suctioning tube through the cap portion CP of the sample container T held in the sample rack L transported on the processing line  4 M of the sample transport unit  4  to suction the blood sample from the sample container T. The sample dispensing unit  61  drops the suctioned blood sample on the glass slide. The smearing unit  62  smears the blood sample dropped on the glass slide, and dries and prints the dropped blood sample on the glass slide. 
     The glass slide transport unit  63  is provided to house the glass slide on which the blood sample is smeared by the smearing unit  62  in a cassette not illustrated in the drawing and transports the cassette. The staining unit  64  supplies the staining solution to the glass slide in the cassette transported to a staining position by the glass slide transport unit  63 . The controller  65  controls the sample dispensing unit  61 , smearing unit  62 , glass slide transport unit  63 , and staining unit  64  in accordance with a sample preparation guidance obtained from the sample transport apparatus  3  to carry out the smear sample preparation described earlier. 
     [Structure of System Controller  8 ] 
     The system controller  8  including a computer controls the overall operation of the sample processing system  1 . The system controller  8  receives the rack number of the sample rack L from the sample loading and collection apparatus  2  and decides a destination of the sample rack L, and then transmits transport instruction data indicating the decided destination to the sample transport apparatus  3 . 
       FIG. 9  is a block diagram illustrating a structure of the system controller  8  according to the present embodiment. The system control device  8  is run by a computer  8   a . As illustrated in  FIG. 9 , the computer  8   a  has a main body  81 , an image display device  82 , and an input device  83 . The main body  81  has a CPU  81   a , a ROM  81   b , a RAM  81   c , a hard disc  81   d , a readout device  81   e , an input/output interface  81   f , a communication interface  81   g , and an image output interface  81   h . The CPU  81   a , ROM  81   b , RAM  81   c , hard disc  81   d , readout device  81   e , input/output interface  81   f , communication interface  81   g , and image output interface  81   h  are connected to one another by a bus  81   j.    
     The readout device  81   e  can read out a computer program  84   a  which makes the computer function as the system controller  8  from a transportable recording medium  84 , and install the computer program  84   a  in the hard disc  81   d.    
     &lt;Structure of Test Information Management Apparatus  9 &gt; 
     The test information management apparatus  9  is an apparatus which manages information relating to tests performed in a facility, generally called LIS (Laboratory Information System), which is connected not only to the blood cell analysis apparatus  5  but also to a clinical sample testing apparatus. The test information management apparatus  9  receives a measurement order inputted by an operator or transmitted from a device such as an electronic chart system, and stores and manages the received measurement order. Further, the test information management apparatus  9  receives an order request from the system controller  8  and transmits the requested measurement order to the system controller  8 , and also receives an analysis result from the blood cell analysis apparatus  5  and stores and manages the received analysis result. 
     The test information management apparatus  9  including a computer has CPU, ROM, RAM, hard disc, and communication interface. The communication interface is connected to the LAN mentioned earlier and can thereby communicate with the system controller  8  and the information processing unit  54  of the blood cell analysis apparatus  5 . The measurement order is stored in the hard disc. The measurement order includes information such as sample ID and sample components to be measured. When the test information management apparatus  9  receives measurement order request data including the sample ID from any other apparatus, the test information management apparatus  9  reads out measurement data relevant to the received sample ID from the hard disc and transmits the data to the apparatus which requested the data. The rest of the structure of the test information management apparatus  9  is similar to the other computers described so far, and will not be any further described. 
     [Operation of Sample Processing System] 
     An operation of the sample processing system according to the present embodiment is described below. Below is described a flow of the sample rack transport operation by the sample transport unit  3   a . However, the sample transport units  3   b  and  3   c  carry out a similar sample rack transport operation. 
     &lt;Transport Mode Setting Operation&gt; 
     The system controller  8  executes a transport mode setting process, and the sample processing system  1  accordingly sets the transport mode.  FIG. 10  is a flow chart illustrating processing steps for setting the transport mode carried out by the system controller  8 . The transport mode is set as initial setting when, for example, the sample processing system  1  is installed in a facility. When an operator or a serviceman sets the transport mode, he or she inputs an instruction to display a transport mode setting screen to the system controller  8  by manipulating the input device  83  of the system controller  8 . When the CPU  81   a  of the system controller  8  receives the instruction to display the transport mode setting screen (Step S 101 ), the CPU  81   a  displays the transport mode setting screen (not illustrated in the drawing) on the image display device  82  (Step S 102 ). The transport mode setting screen is a screen used to set one of a first transport mode and a second transport mode. An instruction to set the first transport mode or an instruction to set the second transport mode can be inputted to the screen. In the first transport mode, the measurement unit for first test only, more specifically the measurement unit used to perform an initial sample measurement, and the measurement unit for retest only, more specifically the measurement unit used to perform a second sample measurement onwards are selected, and the sample rack is transported so that the first test and the retest are performed by the different measurement units. In the second mode, all of the measurement units can be used for the first test and retest both, and the sample rack is transported so that the measurement unit which first tested the sample can retest the same sample. 
     Next, the CPU  81   a  receives the instruction to set the transport mode (Step S 103 ), and determines whether the instructed transport mode is the first transport mode or the second transport mode (Step S 104 ). When it is determined that the instructed transport mode is the first transport mode (“first transport mode” in Step S 104 ), the CPU  81   a  sets the first transport mode (Step S 105 ). When it is determined that the instructed transport mode is the second transport mode (“second transport mode” in Step S 104 ), the CPU  81   a  sets the second transport mode (Step S 106 ). To specifically describe the transport mode setting, information indicating the instructed transport mode is stored as a set value in the hard disc  81   d . More specifically, information indicating the first transport mode is stored as a set value in the hard disc  81   d  when it is instructed to set the first transport mode, and information indicating the second transport mode is stored as a set value in the hard disc  81   d  when it is instructed to set the second transport mode. After the transport mode is thus set, the CPU  81   a  terminates the processing steps. 
     &lt;Sample Rack Transport Operation in First Transport Mode&gt; 
     Next is described a sample rack transport operation carried out by the sample processing system  1  when the first transport mode is set. In the description below, the measurement units  51  and  52  are used for first test only, and the measurement unit  53  is used for retest only. 
     The sample rack L holding a plurality of sample containers T is loaded in the sample loading unit  1  by an operator. The measurement orders of the respective samples retained in the sample rack L are stored in the test information management apparatus  9 . The measurement orders are stored in a measurement order database provided in the hard disc  91   d .  FIG. 11  is a schematic illustration of measurement orders of pre-measurement samples stored in the test information management apparatus  9 . As illustrated in  FIG. 11 , a measurement order database DB is a table format database. The measurement order database has fields, respectively showing rack ID, holding position in the sample rack L, sample ID, and measurement items which are CBC, DIFF, RET, and SP (smear sample preparation). The measurement order of each sample is registered as a sample record in the measurement order database DB. In the description of the present embodiment, one or both of CBC and DIFF are measurement items as targets to be performed when the sample is first tested, and one or both of RET and SP are measurement items as targets to be performed when the sample is tested again depending on a result of the first test. It is known from the measurement orders of  FIG. 11  that all of the samples are tested for the first time. Therefore, information indicating a target to be performed “1” is stored in one or both of cells of CBC and DIFF, while information indicating a non target to be performed “0” is stored in one or both of cells of RET and SP. 
     When the sample rack L is loaded in the sample loading unit  21  and an instruction to start processing of the sample is inputted by the operator, the sample rack L is transported from the sample loading unit  21  to the pre-processing unit  22  so that the sample ID is read out from the sample barcode label BL of the sample container T and the rack ID is read out from the rack barcode label of the sample rack L by the barcode readout device  22   b  of the pre-processing unit  22 . The sample ID and the rack ID thus read out are transmitted to the test information management apparatus  9  by way of the system controller  8  so that the measurement order relevant thereto is requested. The test information management apparatus  9  reads out the requested measurement order of the sample ID from the hard disc  91   d  and transmits the measurement order to the system controller  8 . The system controller  8  decides which of the measurement units is the transport destination of the sample rack L based on the received measurement order and the current operation conditions of the measurement units  51  and  52  at the time, and transmits an instruction to send the sample rack to the decided destination to the sample transport apparatus  3 . 
     The sample rack L is transported from the pre-processing unit  22  to the sample transport apparatus  3 , and then transported by the sample transport unit  3   a ,  3   b  to the measurement line  3   a M or  3   b M of the measurement unit  51  or  52  which is the transport destination. Then, the sample container T is transferred to the sample supply position  35   c  and fetched into the measurement unit  51  or  52 . The system controller  8  supplies the sample ID of each sample held in the transported sample rack L to the information processing unit  54 . The information processing unit  54  transmits measurement order request data including the sample ID to the test information management apparatus  9 . The test information management apparatus  9  reads out the measurement order relevant to the sample ID included in the measurement order request data from the measurement order database DB, and transmits the measurement order to the information processing unit  54 . In the measurement unit  51  or  52 , the sample is suctioned from the sample container T and measured based on the measurement order requested for the suctioned sample. After the sample suctioning is completed, the sample container T is discharged from the measurement unit  51  or  52  and returned to the original holding position in the sample rack L. A result of the sample measurement is supplied to the information processing unit  54 , and the information processing unit  54  analyzes the measurement result to obtain an analysis result of the sample. The information processing unit  54  transmits the sample analysis result to the test information management apparatus  9 . The test information management apparatus  9  which received the analysis result updates the measurement order of the sample relevant to the analysis result with a post-analysis measurement order in the measurement order database DB. 
       FIG. 12  is a schematic illustration of measurement orders of post-measurement samples stored in the test information management apparatus  9 . In the measurement orders illustrated in  FIG. 12 , the information indicating a non target to be performed “0” is stored in all of CBC, DIFF, RET, and SP because the first test is already completed for all of the samples. 
     The test information management apparatus  9  processes the received analysis result to decide whether the sample should be retested, and decide a measurement item when the retest is requested. The test information management apparatus  9  registers the decision on whether the retest is necessary and the measurement item in the record of the target sample in the measurement order database DB.  FIG. 13  is a schematic illustration of measurement orders of post-analysis samples stored in the test information management apparatus  9 . In the measurement orders illustrated in  FIG. 13 , the information indicating a retesting item “1” is stored in the cells of RET and SP of the measurement order of the sample having a sample ID “P 121 ”. The information indicating a non retesting target to be performed “0” is stored in the cells of RET and SP of the measurement order of the sample having a sample ID “P 122 ”. In the measurement order of the sample having a sample ID “P 129 ”, “1” is stored in the cell of RET, and “0” is stored in the cell of SP. In the measurement order of the sample having a sample ID “P 130 ”, “0” is stored in the cell of RET, and “1” is stored in the cell of SP. 
     The sample containers T retained in the sample rack L are consecutively fetched at the holding position  1  into the measurement unit  51  or  52  so that the samples are measured. When all of the sample containers T are returned from the measurement unit  51  or  52  to their sample rack L, the sample rack L is transferred to the post-analysis rack delivering position  391  of the measurement line  3   a M or  3   b M by the sample transport unit  3   a  or  3   b , and then pushed into the post-analysis rack holding section  34  from the post-analysis rack delivering position  391  by the rack delivering section  39 . 
       FIG. 14  is a flow chart illustrating processing steps for controlling the transport of the sample rack L carried out by the sample transport unit in the first transport mode. The controller  32  determines whether the post-analysis rack holding section  34  receives the sample rack L from the measurement line  3   a M or  3   b M (Step S 201 ). Whether the sample rack L is received is determined by monitoring an output signal of the rack sensor  372 . When the receipt of the sample rack L in the post-analysis rack holding section  34  is not detected (NO in Step S 201 ), the controller  32  repeatedly carries out the processing step of S 201  until the receipt of the sample rack L is detected. When the receipt of the sample rack L in the post-analysis rack holding section  34  is detected (YES in Step S 201 ), the controller  32  moves the rack senders  34   b  to transfer the sample rack L to a position immediately before the skipping line  3   a F or  3   b F in the post-analysis rack holding section  34  (Step S 202 ) and stops the sample rack L there. Then, the controller  32  transmits transport instruction request data including the sample IDs of the samples contained in the sample rack L to the system controller  8  (Step S 203 ). 
       FIG. 15  is a flow chart illustrating processing steps for instructing the transport of the sample rack L carried out by the system controller  8  in the first transport mode. When the system controller  8  receives the transport instruction request data from the sample transport apparatus  3  (Step S 301 ), the CPU  81   a  inquires the test information management apparatus  9  of the measurement order using the sample ID included in the transport instruction request data (Step S 302 ). The test information management apparatus  9  reads out the measurement order corresponding to the sample ID included in the inquired data from the measurement order database DB, and transmits the measurement order to the system controller  8 . The measurement order transmitted then relates to the sample for which the first test is done and the analysis result is already processed. Therefore, the measurement order includes the determination result on whether the retest is necessary illustrated in  FIG. 13 . 
     The CPU  81   a  determines whether a given period of time (120 seconds) passed after the inquiry of the measurement order was made (Step S 303 ). In the case where the given period of time has not yet passed (YES in Step S 303 ), the CPU  81   a  determines whether the measurement orders of all of the samples contained in the sample rack L are received (Step S 304 ). In the case where there is any measurement order not yet received (NO in Step S 304 ), the CPU  81   a  returns the processing to the processing step of S 303 . 
     In the case where in Step S 303 , it is determined that the given period of time has passed (NO in Step S 303 ) since the inquiry of the determination order, the CPU  81   a  transmits the transport instruction data indicating that the transport destination of the sample rack L is the sample collection unit  23  to the sample transport apparatus  3  (Step S 305 ), and terminates the processing steps. 
     When in Step S 304 , the measurement orders of all of the samples contained in the sample rack L on standby is received in the post-analysis rack holding section  34  (YES in Step S 304 ), the CPU  81   a  decides the transport destination of the sample rack L based on the received measurement orders (Step S 306 ). In the case where any of the measurement orders includes RET or SP as an item to be retested during the processing step of S 304 , the measurement unit  53  or the smear sample preparing apparatus  6  which can process REP and SP is decided as the transport destination. When the measurement orders illustrated in  FIG. 13  are obtained, for example, it is necessary to measure RET (reprocess) of the samples having sample IDs P 121  and P 129 , and it is necessary to prepare smear samples (reprocess) of the samples having sample IDs P 121  and P 130 . Accordingly, RET is measured in the measurement unit  53  for retest only, and the smear samples are prepared by the smear sample preparing apparatus  6  for retest only. Therefore, the sample rack L should be transported to the measurement unit  53  and the smear sample preparing apparatus  6  both. The CPU  81   a , therefore, selects the measurement unit  53  positioned on the upstream side of the transport direction as the transport destination of the sample rack L from the two destination apparatuses, measurement unit  53  and smear sample preparing apparatus  6 . In the case where none of the received measurement orders includes any item other than RET as a retesting item in Step S 306 , the measurement unit  53  is similarly decided as the transport destination. In the case where none of the received measurement orders includes any item other than SP as a retesting item, the smear sample preparing apparatus  6  is decided as the transport destination. In the case where none of the received measurement orders includes RET or SP as a retesting item, the sample collection unit  23  is decided as the transport destination. 
     After the processing step of S 306 , the CPU  81   a  transmits the transport instruction data indicating the transport destination thus decided (S 307 ), and terminates the processing steps. 
     Referring to  FIG. 14 , the controller  32  which implemented the processing step of S 203  waits for the transport instruction data to be received (NO in Step S 204 ). When the controller  32  receives the transport instruction data transmitted from the system controller  8  (YES in Step S 204 ), the controller  32  determines whether the transport destination instructed by the transport instruction data is the apparatus on the downstream side of the transport direction, more specifically, whether the transport destination is the measurement unit  53  or the smear sample preparing apparatus  6  (Step S 205 ). In the case where the transport destination instructed by the transport instruction data is the apparatus on the downstream side of the transport direction (YES in Step S 205 ), the controller  32  moves the rack senders  34   b  to transfer the sample rack L to the skipping line  3   a F or  3   b F (Step S 206 ), and then drives the belt conveyer  321  to transport the sample rack L to the sample transport unit on the downstream side (Step S 207 ). Then, the controller  32  ends the processing steps. After that, the sample rack L is transported by the sample transport unit on the downstream side to the transport destination, which is the measurement unit  53  or the smear sample preparing apparatus  6 , so that the samples are retested. 
     In the case where in Step S 205 , it is determined that the transport destination instructed by the transport instruction data is not the apparatus on the downstream side of the transport direction, in other words, the transport destination is the sample collection unit  23  (NO in Step S 205 ), the controller  32  moves the rack senders  34   b  to transfer the sample rack L to the return line  3   a R or  3   b R (Step S 208 ), and then drives the belt conveyer  331  to transport the sample rack L to the sample transport unit or the sample collection apparatus  2  on the upstream side (Step S 209 ). Then, the controller  32  ends the processing steps. The sample rack L is thereafter transported by the collection line  223 ,  217 ,  237  to be finally collected by the sample collection unit  23 . 
     After RET is retested by the measurement unit  53 , an analysis result of the retest is transmitted to the test information management apparatus  9  to decide whether retesting is necessary and any items to be retested in a manner similar to the first test. In the case where the smear sample preparation is determined as necessary for the target sample, “1” is stored in the cell of SP of the measurement order of the target sample in the measurement order database DB. In this case, similarly to the first test, the sample rack L is retained in the post-analysis rack holding section  34  of the sample transport unit  3   c , and the system controller  8  inquires the test information management apparatus  9  of the measurement order. In the case where SP is set as a retesting item in the measurement order obtained by the inquiry, the smear sample preparing apparatus  6  is decided as the transport destination, and the sample rack L is similarly transported to the smear sample preparing apparatus  6 . When the sample rack L is transported to the smear sample preparing apparatus  6 , the sample is suctioned to prepare the smear sample, and the sample rack L is thereafter transported by the return line  4 R,  3   c R,  3   b R,  3   a R to the sample collection unit  23 . In the case where SP is not set as a retesting item in the measurement order obtained by the inquiry, the sample collection unit  23  is decided as the transport destination, and the sample rack L is transported to the sample collection unit  23 . 
     &lt;Sample Rack Transport Operation in Second Transport Mode&gt; 
     Next is described a sample rack transport operation carried out by the sample processing system  1  when the second transport mode is set. In the case where the measurement unit which first tested the sample can remeasure any item of the sample to be retested in the second transport mode, the sample is transported to the measurement unit which first tested the sample. In the case where the measurement unit which first tested the sample is unable to remeasure any item of the sample to be retested, the sample is transported to the measurement units other than the measurement unit which first tested the sample (or smear sample preparing apparatus). 
       FIG. 16  is a flow chart illustrating processing steps for controlling the transport of the sample rack L carried out by the CPU  541   a  of the information processing unit  54  in the second transport mode. After all of the sample containers T are returned to the sample rack L from the measurement unit which first tested the sample, the CPU  541   a  determines whether the sample rack L arrives at the post-analysis rack delivering position  391  (Step S 401 ). When determined that the sample rack L arrived at the position, the CPU  541   a  stops the sample rack there, and transmits the transport instruction request data including the sample IDs of the samples retained in the sample rack L to the system controller  8  by way of the sample transport apparatus  3  (Step S 402 ). 
     The system controller  8  executes processing steps of the transport instruction of the sample rack L in the second transport mode. According to the transport instruction processing steps in the second transport mode, in the case where any of the measurement orders includes RET or SP as an item to be retested when the transport destination of the sample rack L is decided, the measurement unit  51 ,  52 , or  53  which first tested the sample or the smear sample preparing apparatus  6  capable of carrying out SP is decided as the transport destination. In the case where, for example, the first test is carried out by the measurement unit  51  and the measurement orders illustrated in  FIG. 13  are thereby obtained, it is necessary that the measurement unit  51  which first tested the sample measure RET of the samples P 121  and P 129 , and the smear sample preparing apparatus  6  prepare the smear samples of the samples P 121  and P 130 . The CPU  81   a  selects the measurement unit  51  positioned on the upstream side of the transport direction from the measurement unit  51  and the smear sample preparing apparatus  6  as the transport destination of the sample rack L. In the case where none of the received measurement orders includes any item other than RET as an item to be retested, the measurement unit  51  is similarly decided as the transport destination. In the case where none of the received measurement orders includes any item other than SP as an item to be retested, the smear sample preparing apparatus  6  is decided as the transport destination. In the case where none of the received measurement orders includes RET or SP as an item to be retested, the sample collection unit  23  is decided as the transport destination. 
     The transport instruction processing steps in the second transport mode are similar to the transport instruction processing steps in the first transport mode other than the processing steps for deciding the transport destination described so far. Therefore, description of the rest of the processing steps is omitted. 
     The transport instruction data transmitted from the system controller  8  is received by the sample transport apparatus  3  and then transmitted from the sample transport apparatus  3  to the information processing unit  54 . Referring to  FIG. 16 , the controller  541   a  which implemented the processing step of S 402  waits for the transport instruction data to be received (NO in Step S 403 ). When the controller  541   a  receives the transport instruction data (YES in Step S 403 ), the controller  541   a  determines whether the transport destination instructed by the transport instruction data is the measurement unit  51 ,  52 , or  53  which first tested the samples held in the sample rack L on standby at the post-analysis rack delivering position (Step S 404 ). In the case where the transport destination is the measurement unit  51 ,  52 , or  53  which first tested the samples retained in the sample rack L on standby at the post-analysis rack delivering position (YES in Step S 404 ), the CPU  541   a  transmits the measurement order request data including the sample IDs of the samples to the test information management apparatus  9  and makes an inquiry of the measurement orders of these samples (Step S 405 ). The test information management apparatus  9  reads out the measurement orders corresponding to the sample IDs from the hard disc  91   d  and transmits the measurement orders to the information processing unit  54 . 
     Next, the CPU  541   a  determines whether the measurement orders of all of the samples held in the sample rack L are already received (Step S 406 ). In the case where there is any measurement order not yet received (NO in Step S 406 ), the CPU  541   a  returns the processing to the processing step of S 406 . When determined that the measurement orders of all of the samples held in the sample rack L were received (YES in Step S 406 ), the CPU  541   a  drives the belt conveyer  353  in the opposite direction to transport the sample rack L in the direction of X 2  (rightward) along the measurement line  3   a M,  3   b M, or  3   c M (Step S 407 ). Thereafter, to retest all of the samples which need to be retested, the sample containers T are fetched, the samples contained therein are suctioned, measured and analyzed (retested), and the sample containers T are thereafter discharged. Further, the analysis result of retested sample is transmitted to the test information management apparatus  9 , and the measurement order of the sample relevant to the analysis result is updated in the measurement order database DB of the test information management apparatus  9 . At the time, “0” is registered in the cells of RET of retested P 121  and P 129 . Therefore, any sample once measured by the measurement unit  51 ,  52 , or  53  is never measured again by the measurement unit  51 ,  52 , or  53  but is used for the preparation of the smear sample or collected by the sample collection unit  23 . 
     In the case where in Step  404 , it is determined that the instructed transport destination is not the measurement unit  51 ,  52 , or  53  which first tested the samples held in the sample rack L on standby at the post-analysis rack delivering position but is the apparatus on the downstream side of the transport direction (smear sample preparing apparatus  6 ) or the sample collection unit  23  (NO in Step S 404 ), the CPU  541   a  drives the rack delivering section  39  to transfer the sample rack L on standby at the post-analysis rack delivering position  391  to the post-analysis rack holding section  34  (Step S 408 ). 
     After that, the same transport control processing steps as in Steps S 201  to S 209  are carried out by the controller  32 . In the case where the transport destination is the apparatus on the downstream side of the transport direction (smear sample preparing apparatus  6 ), upon the sample rack being transported to the post-analysis rack holding section  34 , the sample transport unit  3   a ,  3   b , or  3   c  transfers the sample rack L to the skipping line  3   a F,  3   b F, or  3   c F using the rack senders  34   b , and then drives the belt conveyer  321  to transport the sample rack to the sample transport unit  4  on the downstream side. Then, the sample rack L is transported to the smear sample preparing apparatus  6  decided as the transport destination by the sample transport unit  4  so that the smear samples of the samples are prepared by the smear sample preparing apparatus  6 . After all of the samples, for which the preparation of their smear samples is requested, are suctioned so that their smear samples are prepared, the sample rack L is transported by the return line  4 R,  3   c R,  3   b R,  3   a R and then sent to the sample collection unit  23 . 
     In the case where the transport destination is the sample collection unit  23 , upon the sample sack L being transported to the post-analysis rack holding section  34 , the sample transport unit  3   a ,  3   b , or  3   c  transfers the sample rack L to the return line  3   a R,  3   b R, or  3   c R using the rack senders  34   b , and then drives the belt conveyer  331  to transport the sample rack to the sample loading and collection apparatus  2 . The sample rack L is thereafter transported by the collection line  223 ,  217 ,  237  to be finally collected by the sample collection unit  23 . 
     As described earlier, the sample loading unit  21  and the sample collection unit  23  are provided on the same side apart from measurement units  51 ,  52 , and  53  and the smear sample preparing apparatus  6 . Therefore, an operator (user) can easily load and collect the sample in one place. 
     After the first test is conducted by the measurement unit  51 ,  52 , or  53 , the sample rack L containing any samples which need to be retested is transported to one of the measurement unit  51 ,  52 , or  53  or the smear sample preparing apparatus  6  along the supply line  3   a S,  3   b S,  3   c S, or  4 S. When the first transport mode is set, the sample rack L holding any samples which need to be retested subsequent to the first test conducted by the measurement unit  51  or  52  is transported in the direction of X 1  along the skipping line  3   a F,  3   b F,  3   c F, or transport line  4 F so that the sample is retested by the measurement unit  53  or the smear sample preparing apparatus  6  for retest only. When the second transport mode is set, the sample rack L holding any samples which need to be retested by the measurement unit  51 ,  52 , or  53  subsequent to the first test conducted by the measurement unit  51 ,  52 , or  53  is transported in the direction of X 2  along the measurement line  3   a M,  3   b M, or  3   c M so that the sample is retested (remeasured) by the measurement unit  51 ,  52 , or  53  which first tested the sample. When the second transport mode is set, the sample rack L holding any samples for which the smear sample preparation requested subsequent to the first test conducted by the measurement unit  51 ,  52 , or  53  is transported in the direction of X 1  along the skipping line  3   a F,  3   b F, or  3   c F, or transport line  4 F so that the sample is processed to be retested by the smear sample preparing apparatus  6 . The sample rack L holding any samples which need to be retested is immediately transported for retesting to one of the measurement units  51 ,  52 , and  53  and the smear sample preparing apparatus  6  to retest the samples. Thus, the sample can be very efficiently retested (reprocessed). 
     The sample rack L holding only the samples which need not be retested subsequent to the first test conducted by the measurement unit  51 ,  52 , or  53  does not pass through the terminal point  3 E of the supply line  3   a S,  3   b S,  3   c S, or  4 S (first transport line) but passes through the rack transport position  3 T by way of the post-analysis rack holding section  34  of the sample transport unit  3   a ,  3   b ,  3   c  and then transferred to the return line  3   a R,  3   b R,  3   c R. Thus, the sample rack L can be speedily collected. 
     [Another Embodiment] 
     In the embodiment described so far, the supply lines  3   a S,  3   b S,  3   c S, and  4 S respectively have the measurement lines  3   a M,  3   b M, and  3   c M, and processing line  4 M, skipping lines  3   a F,  3   b F, and  3   c F, transport line  4 F, pre-analysis rack holding sections  33  and  43 , and post-analysis rack holding sections  34  and  44 . However, the present invention is not necessarily limited thereto. Another possible structure is to provide a supply line linearly extending through the sample transport units, and to provide sample supply positions at which the sample is supplied to the measurement units  51 ,  52 , and  53  and the smear sample preparing apparatus  6  at intermediate positions on the supply line. In the suggested structure, a passage which connects an intermediate position of the supply line to intermediate positions on the return lines  3   a R,  3   b R,  3   c R and  4 R is provided so that any samples which need not be retested alone are transferred to the intermediate position of the return line  3   a R,  3   b R,  3   c R, or  4 R and further in the direction of X 2  along the return line  3   a R,  3   b R,  3   c R, or  4 R to be finally collected by the sample collection unit  23 . 
     The measurement unit  51 ,  52 , or  53  may directly suction the sample from the sample container T kept in the sample rack L on the measurement line  3   a M,  3   b M, or  3   c M. 
     In the embodiment described so far, the sample transport apparatus  3  includes the sample transport units  3   a ,  3   b ,  3   c , and  4  independent from one another. However, the present invention is not necessarily limited thereto. A sample transport apparatus formed as an inseparable single component may be provided on the front side of the measurement units  51 ,  52 , and  53 , and the smear sample preparing apparatus  6  to transport the sample rack L to the measurement units  51 ,  52 , and  53 , and the smear sample preparing apparatus  6 . 
     In the embodiment described so far, all of the measurement units  51 ,  52 , and  53  can measure the same components (CBC, DIFF, RET), however, the present invention is not necessarily limited thereto. For example, the measurement units  51  and  52  can measure CBC and DIFF of the sample but cannot measure RET of the sample, and the measurement unit  53  can measure all of CBC, DIFF, and RET. When the second transport mode is set in addition to the first transport mode, any sample including RET as a target item to be retested is transported to the measurement unit  53  after the first test is over by the skipping line  3   a F,  3   b F,  3   c F, and then retested in the measurement unit  53 . 
     In the embodiment described so far, the sample processing system  1  has the blood cell analysis apparatus  5  which discriminates the blood cells included in the sample according to their types and counts the different types of blood cells respectively. However, the structure of the sample processing system  1  is not limited thereto. The sample processing apparatus may be equipped with any sample analysis apparatus other than the blood cell analysis apparatus, such as immunoassay apparatus, blood coagulation measurement apparatus, biochemical analysis apparatus, or urine analysis apparatus, wherein a sample such as blood or urine is transported to a measurement unit of the sample analysis apparatus. 
     When the second transport mode is set in the embodiment described so far, the sample rack L is left on standby at the post-analysis rack delivering position  391  until the determination is made on whether retesting is necessary. Then, when retesting is requested, the sample rack L is transported in the direction of X 2  along the measurement line  3   a M or  3   b M to be supplied to the measurement unit  51  or  52  which first tested the sample. However, the present invention is not necessarily limited thereto. For example, the sample rack L is left on standby in the post-analysis rack holding section  34  until the determination is made on whether retesting is necessary when the second mode is set. When retesting is requested, the sample rack L is transported in the direction of Y 1  by the rack senders  34   b  and then in the direction of X 2  along the measurement line  3   a M or  3   b M so that the sample rack L is finally supplied to the measurement unit  51  or  52  which first tested the sample. In that case, when it is determined that retesting is unnecessary for the samples retained in the sample rack L on standby in the post-analysis rack holding section  34 , the sample rack L is transferred in the direction of Y 2  to the return line  3   a R or  3   b R by the rack senders  34   b , transported in the direction of X 2  along the return line  3   a R or  3   b R, and then collected by the sample collection unit  23 . 
     In the embodiment described so far, the blood cell analysis apparatus  5  has the three measurement units  51 ,  52 , and  53 , and information processing unit  54 . However, the structure of the blood cell analysis apparatus  5  is not limited thereto. Either a single or a plurality of measurement units may be provided, and the measurement unit and the information processing unit may be integrally formed. It is not necessary that the information processing unit  54  control the mechanisms of the measurement units  51 ,  52 , and  53 . Each of the measurement units may include a controller having a CPU and a memory, wherein the controller controls the measurement unit, and the information processing unit processes measurement data obtained by the measurement unit to generate a sample analysis result. 
     In the embodiment described so far, the single computer  8   a ,  80   a  is solely responsible for all of the processing steps of the computer program  84   a ,  840   a . However, the present invention is not limited thereto. A distributed system may be used, wherein processing steps similar to those of the computer program  84   a ,  840   a  are carried out by a plurality of devices (computers) in a distributed manner. 
     In the embodiment described so far, the sample collection unit  23 , sample loading unit  21 , pre-processing unit  22 , and sample transport apparatus  3  are linearly aligned in the mentioned order from the upstream side of the sample rack transport direction. However, the present invention is not necessarily limited thereto. For example, the sample collection unit  23  may be interposed between the sample loading unit  21  and the pre-processing unit  22 . Accordingly, the sample loading unit  21 , sample collection unit  23 , pre-processing unit  22 , and sample transport apparatus  3  are linearly aligned in the mentioned order from the upstream side of the sample rack transport direction.