Abstract:
A rack is provided wherein the type of micro-plate that is placed on the rack can be determined even when using one type of rack. The rack includes a bottom piece on which micro-plate is placed; at least one shielding component for recognizing the type of micro-plate; and a recognition unit having an enclosure disposed with a shielding component. When the rack is housed in a housing unit of an analyzer main unit, the shielding component is movable with respect to the enclosure so that the shielding component is positioned either in a detection position where detectable by a sensor or in a non-detection position where undetectable by the sensor.

Description:
TECHNICAL FIELD 
     The present invention relates to a rack on which micro-plates are placed and an auto-sampler having the rack. The rack can be used, for example, in auto-samplers that are used in liquid chromatographic analyzers. 
     BACKGROUND 
     Liquid chromatographic analyzers are used for analyzing liquid specimens. A liquid chromatographic analyzer uses a needle to collect liquid specimens, which are injected into an analysis flowpath. When doing this, the liquid specimen is contained in a test tube (container) that is made of transparent glass or plastic. 
     Liquid chromatographic analyzers are sometimes used to analyze many liquid specimens. This has led to liquid chromatographic analyzers that are equipped with auto-samplers (e.g., see Patent Literature 1).  FIG. 5  shows a perspective view of a portion of a liquid chromatographic analyzer.  FIG. 6  shows a perspective view of a portion of an auto-sampler.  FIG. 7  shows a perspective view of a rack on which two micro-plates are placed. 
     The auto-sampler  101  includes: a control unit  160  and housing unit  170 , which houses rack  120 , both of which are disposed in the liquid chromatographic analyzer main unit  150 ; a plurality of types (e.g., 7 types) of micro-plates  10  for holding a plurality of test tubes; and a plurality of types (e.g., 7 types) of racks  120  on which micro-plates  10  are placed. 
     A first micro-plate  10  is a case made of plastic. The first micro-plate  10  has a substantially rectangular parallelepiped shape with, for example, a width (X) of 85 mm, length (Y) of 125 mm and height (Z) of 25 mm. A first hole  11  through a 45 th  hole  11  are formed on the upper surface with five holes arranged in the X-direction (row direction) and nine holes arranged in the Y-direction (column direction). Each hole  11  is cylindrically-shaped which allows the lower half of a test tube to be inserted into a hole  11 . The result is that 45 test tubes are held in the first micro-plate  10  arranged as described in the X-direction and the Y-direction. 
     Furthermore, a second micro-plate (not illustrated) is a case made of plastic. The second micro-plate has a substantially rectangular parallelepiped shape with, for example, a width (X) of 85 mm, length (Y) of 125 mm and height (Z) of 25 mm. A first hole through a 32 nd  hole are formed on the upper surface with four holes arranged in the X-direction (row direction) and eight holes arranged in the Y-direction (column direction). Each hole is cylindrically-shaped which allows the lower half of a test tube to be inserted into a hole. The result is that 32 test tubes are held in the second micro-plate arranged as described in the X-direction and the Y-direction. In other words, different types of micro-plates are available, featuring different number of holes and different hole locations. The description of the third through the seventh micro-plate is omitted here. 
     The first rack  120  includes: a bottom piece  121  having, for example, a width (X) of 94 mm, length (Y) of 260 mm and height (Z) of 20 mm; a recognition unit  122  that is disposed at the front end (positive Y-direction end) of the bottom piece  121 ; and a grip part  123  that is formed at the rear end (negative Y-direction end) of the bottom piece  121 . Two of the first micro-plates  10  can be placed in the Y-direction (column direction) on the upper surface of the bottom piece  121 . 
     The first rack  120  is provided with a recognition unit  122  which allows the control unit  160  of the liquid chromatographic analyzer main unit  150  to automatically recognize the type of micro-plate  10  that is housed in the housing unit  170 . The recognition unit  122  includes: an enclosure  124  that is made of resin and having a rectangular parallelepiped shape; and a first light-shielding plate  125  that is made of resin and protruding 4 mm out in the Y-direction from the enclosure  124 . 
     The second rack (not illustrated) includes: a bottom piece having, for example, a width (X) of 94 mm, length (Y) of 260 mm and height (Z) of 20 mm; a recognition unit that is disposed at the front end (positive Y-direction end) of the bottom piece; and a grip part that is formed at the rear end (negative Y-direction end) of the bottom piece. Two of the second micro-plates can be placed in the Y-direction (column direction) on the upper surface of the bottom piece. A recognition unit includes: an enclosure that is made of resin and having a rectangular parallelepiped shape; and a first light-shielding plate and a second light-shielding plate both made of resin and protruding 4 mm out in the Y-direction and being aligned in the X-direction. In other words, the first rack  120  and the second rack have different number of light-shielding plates  125 , and each micro-plate  10  has its own dedicated rack. 
     The housing unit  170  is provided with a plurality (e.g., three) of photosensors  71  at positions corresponding to the recognition unit  122  of the rack  120 . Beach photosensor  71  includes: an emission unit  71   a  that emits light in the Z-direction; and a detection unit  71   b  which detects light from the emission unit  71   a  with a predetermined distance (e.g., 20 mm) of separation between them. Furthermore, a first photosensor  71 , a second photosensor  71  and a third photosensor  71  are formed to be aligned with each other in the X-direction. In this way, if three photosensors  71  are provided, there are eight possible combinations in which photosensors  71  may be shielded or not shielded from light. Since it is desirable for the housing unit  170  to be able to automatically recognize the absence of rack  120 , it is possible for the housing unit  170  to discriminate among 7 types of micro-plates  10 , excluding the situation where none of the photosensors  71  is shielded from light. 
     The control unit  160  determines the type of micro-plate  10  that is housed in the housing unit  170  based on the status of the recognition information (light-shielding information) that is detected by the three photosensors  71 . 
     For example, if the first rack  120  is housed in the housing unit  170 , since the first rack  120  has the first light-shielding plate  125 , the first photosensor  71  is shielded from light while the second photosensor  71  and the third photosensor  71  are not shielded from light. From this combination, it is determined that a first micro-plate  10  is housed in the housing unit  170 . If a second rack is housed in the housing unit  170 , since the second rack has both the first light-shielding plate and the second light-shielding plate, the first photosensor  71  and the second photosensor  71  are shielded from light while the third photosensor  71  is not shielded from light. From this combination, it is determined that a second micro-plate is housed in the housing unit  170 . 
     PATENT LITERATURE 
     
         
         Patent Literature 1: Unexamined Patent Application Publication H06-034614. 
       
    
     SUMMARY OF THE INVENTION 
     However, with the afore-described rack  120 , as many number of racks  120  is required as the number of different types of micro-plates  10 . Even though it is possible to use one replaceable rack and to swap and replace different recognition units from among a plurality of types of available recognition units, even then, as many recognition units as the number of types of micro-plates  10  would be necessary. 
     Hence, it is the object of the present invention to provide a rack wherein one type of rack can accept and recognize a plurality of different types of micro-plates. 
     To solve the afore-described problems, the rack according to the present invention to be housed in a housing unit of an analyzer main unit comprises: 
     a bottom piece on which micro-plates are placed; 
     at least one shielding component for recognizing the type of micro-plate; and 
     a recognition unit having an enclosure on which the shielding component is installed; 
     wherein: 
     when the rack is housed in the housing unit of the analyzer main unit, the shielding component is movable with respect to the enclosure so that the shielding component is positioned at either a detection position detectable by a sensor that is installed on the housing unit of the analyzer main unit or a non-detection position undetectable by the sensor. 
     With a rack according to the present invention, when, for example, a person performing the analysis places a first micro-plate on the rack, a first shielding component is moved to the detection position. The rack is then placed in the housing unit of the analyzer main unit. This causes the first sensor, but not the second sensor, to detect the shielding component, resulting in the analyzer main unit to recognize what is housed as a first micro-plate. If the person performing the analysis places a second micro-plate on the rack, the first shielding component and the second shielding component are moved to the detection positions. The rack is then placed in the housing unit of the analyzer main unit. This causes the first sensor and the second sensor to detect the shielding components and the analyzer main unit to recognize that the second micro-plate is housed. Furthermore, if the person performing the analysis places a third micro-plate on the rack, the second shielding component is moved to the detection position. The rack is then placed in the housing unit of the analyzer main unit. This causes the second sensor, but not the first sensor, to detect the shielding component, resulting in the analyzer main unit to recognize the presence of a third micro-plate. 
     As afore-described, with a rack according to the present invention, any one of a plurality of different types of micro-plates that is placed on a rack can be recognized while using only one type of rack. 
     With the rack according to the present invention, the sensors may comprise an emission unit for emitting light and a detection unit for detecting, from a predetermined distance away, the light from the emission unit. The shielding component may be positioned at either a detection position or a non-detection position situated between the emission unit and the detection unit. 
     Here, the term “predetermined distance” refers to any distance that allows the insertion of the shielding component. 
     Furthermore, with the rack according to the present invention, the analyzer main unit is provided with a plurality of sensors, and the enclosure for the recognition unit is provided with a plurality of shielding components. Each of the shielding components are made to be independently movable with respect to the enclosure. 
     Furthermore, with the rack according to the present invention, formed on an upper surface of the enclosure of the recognition unit are movement grooves comprising a front-end portion and a rear-end portion having an increased width in plan view and a coupling part having a narrow width and coupling the front-end portion and the rear-end portion; and formed on the shielding component is a vertically extending protruding part whose top portion has a width narrower than the width of its bottom portion; the top portion of the protruding part passing through the movement groove in the horizontal direction while penetrating vertically through the coupling part of the movement groove; the bottom portion of the protruding part passing through the movement groove in the horizontal direction while penetrating vertically through the coupling part of the movement groove; and the shielding component being movable with respect to the enclosure when the protruding part is pressed downwardly. 
     The auto-sampler according to the present invention includes: a rack as afore-described; a plurality of types of micro-plates for holding a plurality of containers; and control unit and a housing unit for housing the racks, both of which are disposed on the analyzer main unit; wherein sensors are disposed on the housing unit, and the control unit determines the type of micro-plate based on recognition information from the sensors. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a perspective view of a part of a liquid chromatographic analyzer that relates to the present invention. 
         FIG. 2  shows a perspective view of one example of rack according to the present invention. 
         FIG. 3  shows a perspective view of the recognition unit that is shown in  FIG. 2 . 
         FIG. 4  shows an exploded perspective view of the recognition unit shown in  FIG. 3 . 
         FIG. 5  shows a perspective view of a part of the liquid chromatographic analyzer. 
         FIG. 6  shows a perspective view of a part of an auto-sampler. 
         FIG. 7  shows a perspective view of a rack with two micro-plates placed thereon. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Embodiments of the present invention are described next with reference to figures. It should be noted that the present invention is not limited to the embodiments described below, and needless to say, various modifications are possible without deviating from the gist of the present invention. 
       FIG. 1  shows a perspective view of a part of a liquid chromatographic analyzer according to the present invention.  FIG. 2  shows a perspective view of a part of a rack according to the present invention. The same numerical references are used for the same components that appear in the description above of the auto-sampler  101 . 
     The auto-sampler  1  includes: a control unit  60  and a housing unit  70  in which racks  20  are housed, both units being provided in the liquid chromatographic analyzer main unit  50 ; a plurality of types (e.g., 7 types) of micro-plates  10  for holding a plurality of test tubes; and one type of rack  20  on which a plurality of types (e.g., 7 types) of micro-plates  10  is placed. 
     The rack  20  includes: a bottom piece  21  having, for example, width (X) of 94 mm, length (Y) of 260 mm and height (Z) of 20 mm; a recognition unit  22  that is disposed at the front end (positive Y-direction end) of the bottom piece  21 ; and a grip part  23  that is formed at the rear end (negative Y-direction end) of the bottom piece  21 . Two micro-plates  10  of different types are placed next to each other in the Y-direction (column direction) on the upper surface of the bottom piece  21 . 
       FIG. 3  shows a perspective view of the recognition unit  22  that is shown in  FIG. 2 .  FIG. 4  shows an exploded perspective view of the recognition unit  22  shown in  FIG. 3 . The recognition unit  22  includes: a resin-made enclosure  24  in the shape of a quadrangular cylinder lying on its side with the central axis about the Y-direction; and four resin-made light-shielding components  25  that are installed on the interior of the enclosure  24 . 
     Formed on the upper surface of enclosure  24  are four movement grooves  26  that penetrate through the upper surface of enclosure  24 . In plan view, each movement groove  26  is shaped like the letter “I” with a quadrangular front-end portion  26   a  with a broad width (X), a quadrangular rear-end portion  26   b  with a broad width (X) and a rectangular coupling part  26   c  having a narrow width (X) and joining the front-end portion  26   a  and the rear-end portion  26   b  in the Y-direction. The first movement groove  26 , second movement groove  26 , third movement groove  26  and fourth movement groove  26  are successively lined up in the X-direction. Furthermore, formed on the top portion of the lower surface of the enclosure  24  at positions corresponding to the movement grooves  26  are four rails (not illustrated) extending in the Y-direction. 
     The light-shielding component  25  includes: a black rectangular parallelepiped-shaped light-shielding part  25   a ; a leaf spring part  25   b  extending from the top of the light-shielding part  25   a  in the negative Y-direction; and a protruding part  25   c  that extends from the tip of the leaf spring part  25   b  in the Z-direction (upwardly). With the protruding part  25   c , the width (X) of the top portion (located higher than height h 1 ) is narrower than the width (X) of the bottom portion (located lower than height h 1 ). This arrangement means that the top portion of the protruding part  25   c  penetrates through the coupling part  26   c  of the movement groove  26  in the Z-direction while passing through the coupling part  26   c  of the movement groove  26  in the Y-direction, and the bottom portion of the protruding part  25   c  penetrates through the coupling part  26   c  of the movement groove  26  in the Z-direction while passing through the coupling part  26   c  of the movement groove  26  in the Y-direction. This means that when the light-shielding component  25  is attached to the movement groove  26  and the person performing the analysis presses in the protruding part  25   c  by distance h 1 , the light-shielding component  25  moves in the Y-direction relative to the enclosure  24 . On the other hand, if the protruding part  25   c  is not pushed in and either the front-end portion  26   a  or the rear-end portion  26   b  is penetrated through, the light-shielding component  25  becomes fixed to the enclosure  24 . At this time, if the protruding part  25   c  is located at the position of the front-end portion  26   a , the light-shielding component  25  protrudes from the enclosure  24  by 4 mm in the Y-direction in a protruded state (detection position). On the other hand, if the protruding part  25   c  is located at the position of the rear-end portion  26   b , the light-shielding component  25  remains contained (no-detection position) within the enclosure  24 . 
     After that, the first light-shielding component  25  is installed in the first movement groove  26 , the second light-shielding component  25  is installed in the second movement groove  26 , the third light-shielding component  25  is installed in the third movement groove  26 , and the fourth light-shielding component  25  is installed in the fourth movement groove  26 . This results in rack  20  to be housed in the housing unit  70  of the liquid chromatographic analyzer main unit  50 . If the first light-shielding component  25  is in the protruded state, first light-shielding component  25  becomes interposed between the emission unit  71   a  of the first photosensor  71  and the detection unit  71   b  (see  FIG. 6 ). On the other hand, if the first light-shielding component  25  remains contained within the enclosure, the first light-shielding component  25  is not interposed between the emission unit  71  of the first photosensor  71  and the detection unit  71   b . Also, if the second light-shielding component  25  is in the protruded state, the second light-shielding component  25  becomes interposed between the emission unit  71   a  of the second photosensor  71  and the detection unit  71   b . On the other hand, if the second light-shielding component  25  is contained within the enclosure, the second light-shielding component  25  is not interposed between the emission unit  71   a  of the second photosensor  71  and the detection unit  71   b . The third light-shielding component  25  and the fourth light-shielding component  25  are positioned similarly as the first light-shielding component  25  with respect to the third photosensor  71  and the fourth photosensor  71 , respectively. 
     On the housing unit  70 , a plurality (e.g., 4) of photosensors  71  is disposed at positions corresponding to the recognition unit  22  of the rack  20 . Each photosensor  71  includes: an emission unit  71   a  that emits light in the Z-direction; and a detection unit  71   b  that detects light from the emission unit  71   a  with a predetermined distance (e.g., 20 mm) of separation. First photosensor  71 , second photosensor  71 , third photosensor  71  and fourth photosensor  71  are formed to be successively lined up in the X-direction. By disposing the four photosensors  71  as afore-described, there are 16 different ways in which light from photosensors  71  can be shielded or not shielded. Incidentally, since it is desirable for the absence of a rack  20  in the housing unit  70  to be automatically recognized, a total of 15 types of micro-plates  10  can be recognized, not including the situation where none of the photosensors  71  is shielded from the light. 
     The control unit  60  uses the recognition information (light-shielding information) detected by the four photosensors  71  to determine the type of micro-plate  10  that is housed in the housing unit  70 . 
     For example, when the person performing the analysis places a first micro-plate  10  on rack  20 , the first light-shielding component  25  is moved to create a protruded state (detection position), and the second through the fourth light-shielding components  25  are moved to the contained state (no-detection position). Rack  20  is then placed in the housing unit  70  of the liquid chromatographic analyzer main unit  50 . This causes the first photosensor  71  to detect the presence of the light-shielding component, and the second through the fourth photosensors  71  to not detect the presence of a light-shielding component  25 . As a result, the control unit  60  recognizes that a first micro-plate  10  is housed within the enclosure. 
     Also, when the person performing the analysis places a second micro-plate on the rack  20 , the first light-shielding component  25  and the second light-shielding component  25  are moved to the protruded state (detection position), and the third through the fourth light-shielding components  25  are moved to the contained state (non-detection position). The rack  20  is then placed in the housing unit  70  of the liquid chromatographic analyzer main unit  50 . This causes the first photosensor  71  and the second photosensor  71  to detect the presence of the light-shielding components  25 , and the third through the fourth photosensors  71  to not detect the light-shielding component  25 . The result is for the control unit  60  to recognize the micro-plate as a second micro-plate. 
     In this way, the person performing the analysis places a micro-plate  10  of a certain type on the rack  20  and moves the light-shielding components  25  that correspond to that certain type of micro-plate  11  to the protruded state (detection position). The control unit  60  then determines the type of micro-plate  10  that is housed in the housing unit  70 . Information regarding the positioning of the light-shielding components  25  and the corresponding type of micro-plate  10  is stored in advance in the control unit  60 . 
     As afore-described, one type of rack  20  can accommodate a variety of types of micro-plates  10  and still recognize particular types of micro-plate  10 . 
     Other Embodiments 
     The afore-described auto-sampler  1  was equipped with photosensors  71  but other devices such as microswitches and magnetic sensors may be used instead. 
     The present invention can be used with racks and the like that are used with auto-samplers that are used with liquid chromatographic analyzers. 
     DESCRIPTION OF THE NUMERICAL REFERENCES 
     
         
           10 : Micro-plate 
           20 : Rack 
           21 : Bottom piece 
           22 : Recognition unit 
           24 : Enclosure 
           25 : Light-shielding component (shielding component) 
           50 : Analyzer main unit 
           70 : Housing unit 
           71 : Sensor (photosensor)