Patent Publication Number: US-2002006362-A1

Title: Sample assaying apparatus

Description:
FIELD OF THE INVENTION  
       [0001] The present invention relates to a sample assaying apparatus. More particularly, the present invention relates to a sample assaying apparatus preferable for a reaction assay between a sample and a reagent, such as an enzyme immunoassay.  
       BACKGROUND OF THE INVENTION  
       [0002] A sample reaction assay as a clinical test in the medical art, such as an enzyme immunoassay, is conducted as follows. First, samples are dispensed into reaction vessels, into which a reagent is poured. While maintaining at a predetermined temperature (if necessary), the samples and the reagent are shaked to equalize the reaction conditions. Thereafter, the reactions characteristic of the reagent are observed. Other than these steps, the samples or the reagent may be diluted, or a new reagent may be added during these steps, or the vessels may be washed.  
       [0003] Accordingly, the reaction assay often requires various complicated steps, troubling the inspector in charge of the assay, especially when the assay is carried out for more number of samples. As a result, recently, automation of the above-described steps is undergoing development.  
       [0004] The above-described various steps are preferably carried out continuously without being interrupted. In addition, some of the steps may be repeated by turns. Thus, a single assaying apparatus, which can perform a plurality of steps of the above-described steps, is demanded.  
       [0005] However, this requires mechanisms for performing the respective steps, as well as a transferring unit for transferring the reaction vessels containing the samples across these mechanisms, which results in a problem of a very large apparatus. Thus, it has been important to solve this problem.  
       [0006] Furthermore, if the above-described diluting step should also be performed by the assaying apparatus, shaking of the samples and the reagents, and shaking of the samples and/or the reagents and a diluent are both necessary. Performing both of the shaking with a single shaking unit extends the time required for the assay. If two shaking units are employed for the respective shaking, the size of the apparatus will undesirably become larger.  
       [0007] The present invention improves the above-described inconveniences of the conventional apparatus, and has an objective of providing a small-sized sample assaying apparatus, which can perform a plurality of steps necessary for a reaction assay between a sample and a reagent in a short time.  
       SUMMARY OF THE INVENTION  
       [0008] The present invention is a sample assaying apparatus for performing a reaction assay for a sample by using a microplate having a plurality of reaction vessels thereon in which the sample and a reagent are subjected to reaction, the apparatus comprising: a reagent/sample tray for mounting a plurality of containers individually containing the reagent or the sample; a base for supporting the reagent/sample tray such that the tray is capable of moving reciprocally; a tray conveying mechanism for conveying the reagent/sample tray reciprocally; a dispensing mechanism for dispensing the sample or the reagent into each reaction vessel of the microplate; and a temperature maintaining mechanism for maintaining the temperature of the microplate at a predetermined temperature.  
       [0009] The dispensing mechanism has a dispenser for dispensing the sample or the reagent and a conveyer for conveying the dispenser in a direction perpendicular to the reciprocating direction of the reagent/sample tray.  
       [0010] Furthermore, a supporter for the microplate is provided at the end of the direction perpendicular to the reciprocating direction of the reagent/sample tray, and the temperature maintaining mechanism is arranged adjacent to the supporter-provided side of the reciprocating region of the reagent/sample tray.  
       [0011] According to the above-mentioned structure, the samples on the reagent/sample tray are carried to the dispensing mechanism by the tray conveying mechanism, where a sample is sucked by the dispenser of the dispensing mechanism. Then, the dispenser is aligned with a predetermined reaction vessel of the microplate via the cooperation of the conveyer of the dispensing mechanism and the tray conveying mechanism, whereby the sucked sample is discharged. This dispensing operation is repeated for each reaction vessel depending on the number of the samples.  
       [0012] Similarly, the reagent on the reagent/sample tray is dispensed into the reaction vessels.  
       [0013] Once the samples and the reagent are dispensed, the microplate on the reagent/sample tray is carried to the temperature maintaining mechanism by the tray conveying mechanism, where the microplate is maintained at a predetermined temperature for a predetermined period of time. As a result, the reactions are promoted. If another reagent needs to be added, the reagent/sample tray is carried by the tray conveying mechanism to be dispensed with another reagent.  
       [0014] In this manner, the reagents and the samples are dispensed into the microplate and the reaction is promoted by maintaining the microplate at the predetermined temperature.  
       [0015] Moreover, the conveyer of the dispensing mechanism conveys the dispenser in a direction perpendicular to the reciprocating direction of the reagent/sample tray. In this case, the dispensing mechanism is positioned with respect to each reaction vessel upon dispensing the samples and the reagent by the cooperation of the reciprocating movement of the reagent/sample tray and the reciprocating movement of the dispenser.  
       [0016] Moreover, a washing mechanism for washing inside each of the reaction vessels of the microplate, wherein the washing mechanism is arranged adjacent to the supporter-provided side of the reciprocating region of the reagent/sample tray.  
       [0017] According to this structure, the microplate is carried to the washing mechanism between or after the above-described operations, where the reaction vessels are washed. Since the washing mechanism is adjacent to the microplate-supporter side of the translation region of the reagent/sample tray, the microplate held by the supporter can be aligned with the washing mechanism by moving the reagent/sample tray.  
       [0018] Moreover, the sample assaying apparatus has a photometer for determining the reaction within each of the reaction vessels of the microplate, wherein the photometer is arranged adjacent to the supporter-provided side of the reciprocating region of the reagent/sample tray.  
       [0019] According to this structure, the reagent is dispensed into the microplate to determine the reaction. Since the determining mechanism is adjacent to the microplate-supporter side of the translation region of the reagent/sample tray, the microplate held by the supporter can be aligned with the determining mechanism by moving the reagent/sample tray. The results of the measurement is either output to an external output device or stored in a memory provided in the sample assaying apparatus.  
       [0020] Moreover, the supporter of the microplate protrudes from the end of the reagent/sample tray in the direction perpendicular to the reciprocating direction of the reagent/sample tray; the temperature maintaining mechanism has a temperature adjuster and a housing for accommodating the temperature adjuster and is arranged to overlap the translation region of the microplate and the supporter; and the housing is provided with a notch where it overlaps with the translation region of the microplate and the supporter.  
       [0021] According to this structure, part of the housing is notched. Therefore, the microplate can be carried inside the housing to perform the heating operation.  
       [0022] Moreover, the supporter of the microplate is formed as a frame so as to hold the microplate with the top and back surfaces thereof being exposed; the temperature adjuster of the temperature maintaining mechanism faces the back surface of the microplate held by the supporter; and the housing has a lid for covering the top surface of the microplate.  
       [0023] According to this structure, the microplate is carried between the heater and the lid of the temperature maintaining mechanism for the heating operation.  
       [0024] Moreover, the sample assaying apparatus has a vibrating mechanism on the reagent/sample tray, for shaking the microplate held on the supporter.  
       [0025] According to this structure, the microplate is shaken after dispensing the sample or the reagent into the microplate or after heating the microplate, to shake the sample and the reagent.  
       [0026] Moreover, the sample assaying apparatus has a region on the supporter for arranging the microplate for reacting the sample and the reagent and for arranging a microplate for performing dilution.  
       [0027] The microplate for performing dilution may have the same structure as that of the reaction microplate. In this case, the subject to be diluted (sample or reagent) is dispensed into the dilution microplate in the same manner as for the reaction microplate, and then diluent is dispensed into each well, thereby performing the dilution operation. The diluent may be pre-arranged on the reagent/sample tray.  
       [0028] After performing the dispensing operations for the reaction microplate and the dilution microplate on the supporter, the microplates are shaken together via the supporter by the vibrating mechanism to shake the contents in the wells. Other operation is the same as the above invention.  
       [0029] By the above-described structures, the present invention aims at achieving the above-described objective. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0030]FIG. 1 is a schematic perspective view showing an arrangement of parts constituting an enzyme immunoreaction assaying apparatus according to one embodiment;  
     [0031]FIG. 2 is a schematic plan view showing the arrangement of parts constituting the enzyme immunoreaction assaying apparatus;  
     [0032]FIGS. 3A and 3B are a plan view and a cross-sectional view (front view) of an assay plate used in the enzyme immunoreaction assaying apparatus, respectively;  
     [0033]FIG. 4 is a perspective view of a reagent/sample tray in use;  
     [0034]FIGS. 5A and 5B are a plan view and a cross-sectional view of a support frame, respectively;  
     [0035]FIG. 6 is an exploded perspective view of a vibrating mechanism;  
     [0036]FIG. 7 is a plan view of a stage unit;  
     [0037]FIG. 8 is a perspective view of a housing with its lid being opened;  
     [0038]FIG. 9 is a perspective view showing the relationship of the translation region of the assay plate/support frame with the notch in the housing of the temperature maintaining mechanism;  
     [0039]FIGS. 10A and 10B are a front view and a side view of a photometer, respectively;  
     [0040]FIG. 11 is a front view of a washing mechanism;  
     [0041]FIG. 12 a is a partial left side view of the washing mechanism;  
     [0042]FIG. 13 is a plan view of a conveyer of the dispensing mechanism;  
     [0043]FIG. 14 is a front view of a dispenser of the dispensing mechanism;  
     [0044]FIGS. 15A and 15B are illustrations showing attachment of tips to the tip of the dispenser, where  
     [0045]FIG. 15A shows the attachment of a sample tip and  
     [0046]FIG. 15B shows the attachment of a reagent tip;  
     [0047]FIGS. 16A and 16B are a perspective view and a front view of a tip disposing unit, respectively;  
     [0048]FIG. 17 is an illustration showing the relationship between a plate cover and the assay plate supported by the support frame;  
     [0049]FIG. 18 is a perspective view of the plate cover; and  
     [0050]FIG. 19 is a flowchart sequentially showing the operations of the enzyme immunoreaction assaying apparatus. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
     [0051] (General Structure of Embodiment of the Invention)  
     [0052] Hereinafter, one embodiment of the present invention will be described with reference to FIGS.  1  to  19 . The present embodiment is an enzyme immunoassaying apparatus  10  which is a sample assaying apparatus for testing an antibody reaction for body fluids, blood, serum or the like from a subject. For this assay, an assay microplate (hereinafter, referred to as an assay plate P) is used which has a plurality of wells P 1  (see FIG. 3) as reaction vessels where enzyme immunoreactions between a sample and reagents take place. FIG. 1 is a schematic perspective view showing an arrangement of assembled parts of the enzyme immunoassaying apparatus  10 . FIG. 2 is a schematic plan view also showing the arrangement of the assembled parts of the enzyme immunoassaying apparatus  10 .  
     [0053] The enzyme immunoassaying apparatus  10  is provided with: a reagent/sample tray  20  for mounting a plurality of reagent bottles S containing different types of reagents and a plurality of sample containers K (see FIG. 4) containing different samples; a base  11  for supporting the reagent/sample tray  20  such that the tray  20  is capable of moving reciprocally; a stage mechanism  30  for conveying the reagent/sample tray  20  reciprocally; a dispensing mechanism  40  for dispensing the sample or the reagent into each well P 1  of the assay plate P; a temperature maintaining mechanism  50  for maintaining the temperature of the assay plate P at a predetermined temperature; a washing mechanism  60  for washing inside each well P 1  of the assay plate P; a photometer  70  for determining an enzyme immunoreaction in each well P 1  of the assay plate P; a plate cover  12  for preventing the sample or the reagent in each well P 1  of the assay plate P from drying; and a tip disposing unit  13  for disposing later-described disposable tips T 1 , T 2  and T 3 . The reference numeral  14  denotes a power source for supplying electric power to each part of the apparatus. The enzyme immunoassaying apparatus  10  is connected to a personal computer (not shown) as a unit for controlling the operation of each part of the apparatus.  
     [0054] Hereinafter, details of each part will be described.  
     [0055] (Assay Plate and Dilution Plate)  
     [0056] First, the assay plate P will be described before describing the structures of other parts. A microplate for diluting the later-described samples or reagents (hereinafter, referred to as a dilution plate U) will also be described here since it has the same structure as that of the assay plate P. FIGS. 3A and 3B are a plan view and a cross-sectional view (front view) of an example of the assay plate P (the dilution plate U), respectively. A total of 96 (12 in width×8 in length) wells P 1  (U 1 ) are arranged on the surface of the assay plate P (the dilution plate U). Each well P 1  (U 1 ) has a flat bottom and an open top. The wells of the assay plate P (dilution plate U) are not limited to flat bottoms, and may have semi-spherical bottoms.  
     [0057] The assay plate P is made of transparent plastic so that when a light beam of a predetermined wavelength is radiated from above, absorbance can be determined based on the beam transmitted through the assay plate P, thereby obtaining measurements of the enzyme immunoreactions. The entire inner surface of each well P 1  is applied with a reagent in advance, into which the sample or other reagent may be dispensed. The dilution plate U is not necessarily transparent and no reagent is applied thereto.  
     [0058] (Base)  
     [0059] The base  11  is a plate-like member on which the above-mentioned parts of the enzyme immunoassaying apparatus  10  are mounted. The base  11  and other parts are all accommodated in an apparatus case (not shown).  
     [0060] (Reagent/Sample Tray)  
     [0061] Next, the reagent/sample tray  20  will be described with reference to FIGS. 2 and 4. FIG. 4 is a perspective view of the reagent/sample tray  20  in use. The reagent/sample tray  20  is mounted on the base  11  via the tray conveying mechanism  30 . The reagent/sample tray  20  is provided with a rectangular tray board  27  and a group of stock units arranged on the tray board  27 .  
     [0062] The group of stock units on the tray board  27  is arranged in order in the Y-direction, the direction along which the tray conveying mechanism  30  moves reciprocally. Specifically, the stock units include a reagent stock unit  21  for holding the reagent bottles S containing the different types of reagents appropriate for the assay system, a sample stock unit  22  for holding the plurality of sample containers K containing individual samples, a sample tips stock unit  23  for holding a plurality of sample tips T 1  used for dispensing each sample into a corresponding well P 1  of the assay plate P, a diluent tips stock unit  24  for holding a plurality of diluent tips T 2  corresponding to respective wells P 1 , and a reagent tips stock unit  25  adjacent to the reagent stock unit  21  and the sample stock unit  22 , for holding reagent tips T 3  for dispensing the corresponding reagents.  
     [0063] The reagent stock unit  21  has seven sockets  21   a  lined in the X-direction (direction perpendicular to the above-mentioned Y-direction) for receiving the reagent bottles S. The number of the sockets, however, is not limited thereto and may be increased or reduced at need.  
     [0064] The sample stock unit  22  is formed as a tray, and is detachable from the tray board  27 . The sample stock unit  22  has a total of 98 (14 in X-direction×7 in Y-direction) sockets  22   a  where the sample containers with closed bottoms and open tops are inserted and held. The total number of the sockets  22   a  is also not limited thereto.  
     [0065] The sample tips stock unit  23  and the diluent tips stock unit  24  are arranged adjacent to each other in the X-direction. Both of the stock units are adjacent to the sample stock unit  22 . Each of the tips stock units  23  and  24  is detachably held on a holder  26  mounted on the tray board  27 . The tips stock units  23  and  24  have the same structures. The sample tip T 1  and the diluent tip T 2  have the same structures as well. The tips T 1  and T 2  are detachably held in the tips stock units  23  and  24 , respectively.  
     [0066] To be more specific, each of the tips T 1  and T 2  is a tube with a tapered end (see FIG. 15A). The root of the tip T 1  or T 2  is attached to the tip of a dispensing nozzle of the later-described dispensing mechanism  40  in order to suck and discharge the sample or the diluent via the tapered end of the tip. In order to prevent the individual samples from mixing with each other, each of the tips T 1  and T 2  are individually provided for each well P 1  or U 1  of the assay plate P or the dilution plate U.  
     [0067] The above-described reagent tips stock unit  25  is provided at one end of the tray board  27  in the X-direction. The reagent tips stock unit  25  can hold nine reagent tips T 3  in the Y-direction. Each of the tips T 3  is detachable from the tips stock unit  25 . The number of tips to be held is not limited, but preferably higher than the number of the reagent bottles held in the reagent stock unit  21 .  
     [0068] To be more specific, each of the reagent tips T 3  is a tube with a tapered end similar to the above-described sample tips T 1  (see FIG. 15B). Similarly, the root of the tip T 3  is attached to the tip of the dispensing nozzle of the later-described dispensing mechanism  40  in order to suck and discharge the reagent via the tapered end of the tip. The reagent tips T 3  have a larger diameter and a longer length than the sample tips T 1 , and thus can contain for a greater volume. The reagent tips T 3  are individually provided for the respective reagent bottles S in order to prevent the reagents from mixing with each other.  
     [0069] (Support Frame)  
     [0070] A support frame  28  for supporting the assay plate P and the dilution plate U is provided on the tray board  27  via a vibrating mechanism  80 . FIGS. 5A and 5B are a plan view and a cross-sectional view (cut along line W-W in FIG. 5A) of the support frame  28 , respectively. FIG. 6 is an exploded perspective view of the vibrating mechanism  80 .  
     [0071] The support frame  28  and the vibrating mechanism  80  are provided at one end of the tray board  27  in the X-direction, adjacent to the above-described diluent tips stock unit  24 . The support frame  28  is a plate having hollows  28   a  and  28   b  for placing the assay plate P and the dilution plate P, respectively. The shapes and the sizes of the hollows  28   a  and  28   b  are such that the plates P and U fit within the hollows  28   a  and  28   b , respectively. The support frame  28  is arranged on the tray board  27  such that the longitudinal sides of the plates P and U (the side with  12  wells) are placed in the Y-direction. As shown in FIG. 4, the right half of the support frame  28  where the assay plate P is to be arranged protrudes from the tray board  27  in the X-direction.  
     [0072] As shown in FIGS. 5A and 5B, the bottom surface of the hollow  28   a  of the support frame  28  is provided with a large aperture  28   c  penetrating through the back of the support frame  28 . The size of the aperture  28   c  is determined such that almost the entire area (except the circumference) of the back of the assay plate P is exposed. The aperture  28   c  is provided for heating the assay plate P from underneath by the later-described temperature maintaining mechanism  50  and for detecting the transmitted light beam by the photometer  70 .  
     [0073] A wash bath  29  is provided in the support frame  28  and adjacent to the hollow  28   a  in the Y-direction, for washing the tip of the later-described sucking nozzle of the washing mechanism  60 . The width of the wash bath  29  is generally equal to the width of the assay plate P in the X-direction. During the washing process, the washing solution is repeatedly discharged into and sucked from the wash bath  29  to wash the tip of the sucking nozzle.  
     [0074] (Vibrating Mechanism)  
     [0075] As described above, the support frame  28  is mounted on the tray board  27  via the vibrating mechanism  80 . As shown in FIG. 6, the vibrating mechanism  80  is provided with: a base plate  81  firmly mounted on the tray board  27  via four legs; a vibrating motor  82  firmly attached to the back surface of the base plate  81 , with the rotation axis being upright (i.e., perpendicular to both X- and Y-directions, hereinafter this direction is referred to as Z-direction); an eccentric cam  83  attached to the driving axis of the vibrating motor  82 ; a bearing  84  for rotatably connecting an eccentric shaft  83   a  of the eccentric cam  83  to the support frame  28 ; a slider connector  85  for connecting the support frame  28  to the base plate  81  such that the support frame  28  is capable of sliding in horizontal directions (in both X- and Y-directions); and an original position sensor  86  for detecting the original position of the support frame  28  with respect to the base plate  81 .  
     [0076] The vibrating motor  82  is a servomotor which can freely control the number and the angle of rotation, and which always ends the vibration at a predetermined rotation angle so that the position of the support frame  28  after the vibration does not change with respect to the base plate  81 .  
     [0077] One end of the eccentric cam  83  is connected to the driving axis of the vibrating motor  82 , and the other end is provided with the eccentric shaft  83   a  that is parallel but eccentric to the driving axis. By connecting the eccentric shaft  83   a  to the support frame  28  via the bearing  84 , driving the vibrating motor  82  will cause a circular motion of the support frame  28  with the driving axis being the center and the eccentric distance of the eccentric shaft  83   a  being the radius of the movement.  
     [0078] The connector  85  for connecting the base plate  81  to the support frame  28  is formed of a combination of two sliders that allow sliding movement of one slider in the longitudinal direction of the other slider. The connector  85  is mounted between the base plate  81  and the support frame  28 , such that one slider slides in the X-direction while the other slides in the Y-direction. Thus, the support frame  28  can slide in any horizontal direction without changing its angle. Accordingly, driving the vibrating motor  82  will move the support frame  28  in a circular movement parallel to the horizontal surface without changing its angle.  
     [0079] A bump  83   b  is provided on the circumferential surface of the eccentric cam  83 . The above-described original position sensor  86  detects the presence of the bump  83   b  and outputs a detection signal to the personal computer that controls the operation of the enzyme immunoassaying apparatus  10 . Based on the detection of the bump  83   b , the personal computer judges that the support frame  28  is at the original position and halts the vibrating motor  82  at that rotation angle, thereby ending the vibration operation. Accordingly, the position of the support frame  28  with respect to the base plate  81  can be constant before and after the vibration operation, thereby preventing malfunctions caused by misalignment of the assay plate P upon other operations (e.g., dispensing, washing, heating, assaying, and the like of the assay plate P).  
     [0080] (Stage Unit)  
     [0081] Next, the stage unit  30  will be described with reference to FIGS. 2 and 7. The stage unit  30  is provided with: two guiding shafts  31   a  and  31   b  for guiding the reagent/sample tray  20  in the Y-direction; sliders  32   a  and  32   b  firmly attached on the back surface of the reagent/sample tray  20  and capable of sliding along the guiding shafts  31   a  and  31   b , respectively; an endless belt  34  stretching in the Y-direction between two driven pulleys  33   a  and  33   b ; a driving motor  35  as the source for driving the endless belt  34 ; a driving pulley  36  attached to the output axis of the driving motor  35 ; a reduction pulley  37  coaxially connected to the driven pulley  33   a ; and a transmission belt  38  for transmitting torque of the driving pulley  36  to the reduction pulley  37 .  
     [0082] Both of the guiding shafts  31   a  and  31   b  extend in the Y-direction and are fixed to the base  11  (not shown in FIG. 7) at both ends. The sliders  32   a  and  32   b  include linear motion ball bearings engaging with the guiding shafts  31   a  and  31   b , respectively, so that they can slide along the guiding shafts  31   a  and  31   b , respectively. The sliders  32   a  and  32   b  are attached to the back surface of the tray board  27  of the reagent/sample tray  20  so that the entire reagent/sample tray  20  can reciprocate in the Y-direction.  
     [0083] The driven pulleys  33   a  and  33   b  and the endless belt  34  are all arranged near the guiding axis  31   b . The slider  32   b  is connected at the center of the endless belt  34  via a bracket  32   c . Thus, the endless belt  34  is driven to move the reagent/sample tray  20  reciprocally via the slider  32   b.    
     [0084] The reduction pulley  37  and the driven pulley  33   a  are coaxially supported at both ends of a shaft for an interlocking movement. The driving pulley  36  has a smaller diameter than that of the reduction pulley  37  so that the rotation speed transmitted to the reduction pulley  37  is reduced.  
     [0085] The driving motor  35  is a servomotor capable of controlling the rotary amount. By controlling the rotary amount, the reagent/sample tray  20  can be aligned in the Y-direction.  
     [0086] (Temperature Maintaining Mechanism)  
     [0087] Referring to FIG. 2, the temperature maintaining mechanism  50  is placed at the front side (i.e., lower side in FIG. 2) of the base  11 , adjacent to the support frame  28  side (i.e., the right side in FIG. 2) of the reciprocating region of the reagent/sample tray  20 . The temperature maintaining mechanism  50  will be described with reference to FIGS. 8 and 9. FIG. 8 is a perspective view of the temperature maintaining mechanism  50  with a later-described lid  56  being opened. FIG. 9 is a perspective view showing the relationship between the translation region R of the assay plate/support frame and a housing  52  of the temperature maintaining mechanism  50 .  
     [0088] The temperature maintaining mechanism  50  is provided with a heater  51  as a temperature adjuster and the housing  52  for accommodating the heater  51 . The temperature of the heater  51  can be set by a control panel (not shown). The temperature adjustor is not limited to the heater and may be, for example, a Peltier element which can be used not only for heating but also for cooling.  
     [0089] The housing  52  includes a main body  53  for holding the heater  51 , four legs  54  for supporting the main body  53  on the base  11  (not shown), and a lid  56  which can be opened and closed and which is positioned at the upper end of a side wall  55  standing on the upper surface of the main body  53 .  
     [0090] The above-described heater  51  is provided on the upper surface of the main body  53 . The lid  56  is attached to the side wall  55  such that when it is in the closed position, it faces the heater  51  via the translation region of the assay plate P/support frame  28 . Specifically, a gap is provided between the main body  53  and the lid  56 , which allows the thickness (height) of the support frame  28  holding the assay plate P so that the assay plate P and the support frame  28  conveyed by the movement of the reagent/sample tray  20  can be inserted into the gap. When the assay plate P is inserted between the main body  53  and the lid  56 , the assay plate P is sandwiched with the heater  51  below and the lid  56  above. As described above, since the hollow  28   a  of the support frame  28  has the aperture  28   c , the back surface of the assay plate P directly faces the heater  51  without any shielding. Thus, heat from the heater  51  can efficiently be transferred to the back surface of the assay plate P. In addition, since the lid  56  is in the vicinity of the openings of the wells P 1  of the assay plate P, the moisture contained in the sample, the reagents or the like in the wells P 1  can be prevented from evaporating.  
     [0091]FIG. 9 shows the housing  52  with the lid  56  being closed. In FIG. 9, symbol R represents the translation region of the assay plate P/support frame  28  defined by the movement of the reagent/sample tray  20 . As can be appreciated from the figure, the temperature maintaining mechanism  50  is arranged on the base  11 , overlapping with the end of the region R. The housing  52  is notched for receiving the translation region R of the assay plate/support frame. Specifically, notches  52   a  and  52   b  facing the Y- and X-directions, respectively, are formed to allow the assay plate P and the support frame  28  to be guided inside the housing  52  according to the translation of the reagent/sample tray  20 .  
     [0092] (Photometer)  
     [0093] Referring to FIG. 2, the photometer  70  is arranged on the base  11 , behind (i.e., upper side in FIG. 2) the temperature maintaining mechanism  50  in the Y-direction, and adjacent to the support frame  28  side (i.e., right side in FIG. 2) of the reciprocating region of the reagent/sample tray  20 . The photometer  70  will be described with reference to FIGS. 10A and 10B, which are a front view and a side view of the photometer  70 , respectively.  
     [0094] The photometer  70  is provided with: a radiation unit  71  for radiating light from a halogen lamp  71   a  as a light source to the wells P 1  of the assay plate P; a sensor supporter  72  including a photodiode  72   a  as a light-receiving sensor; a filter supporter  73  including a various types of band pass filters  73   a  appropriate for determinations; a filter selecting means  74  for driving the filter supporter  73 ; a bracket  75  for supporting the radiation unit  71 , the sensor supporter  72  and the filter supporter  73 ; a base plate  76  mounted on the base  11  (not shown in FIGS. 10A and 10B) with two legs  76   a ; a guiding member  77  mounted on the base plate  76 ; a slider  78  slidable along the guiding member  77 ; and a positioning means  79  for moving the slider  78  reciprocally.  
     [0095] The radiation unit  71  includes the halogen lamp  71   a , a guiding tube  71   b  which transmits the light from the halogen lamp  71   a , and a mirror  71   c  that reflects off the transmitted light toward the sensor supporter  72 . The guiding tube  71   b  extends from the bracket  75  in the X-direction. The distance from the root of the guiding tube  71   b  to the mirror  71   c  on the tip of the guiding tube  71   b  is longer than the width (shorter side) of the assay plate P in the X-direction.  
     [0096] The disk-shaped filter supporter  73  is inserted between the halogen lamp  71   a  and the guiding tube  71   b . Various types of band pass filters  73   a  with different pass bands (five types in the present embodiment) are provided along the circumference of the filter supporter  73 . A throughhole  73   b  without the band pass filter  73   a  is also provided along the circumference of the filter supporter  73 .  
     [0097] The filter selecting means  74  is provided with: a servomotor  74   a  for rotating the filter supporter  73 ; an original position bump  74   b  provided on the peripheral of the filter supporter  73 ; and an original position sensor  74   c  for detecting the original position bump  74   b . The original position bump  74   b  is detected by the original position sensor  74   c , and then the filter supporter  73  is rotated by a predetermined angle by the servomotor  74   a , thereby aligning the desired band pass filter  73   a  with respect to the halogen lamp  71   a  and then emitting light wave of a predetermined wavelength from the radiation unit  71 .  
     [0098] The sensor supporter  72  also extends from the bracket  75  in the X-direction. The distance from the root of the sensor supporter  72  to the photodiode  72   a  at the tip of the sensor supporter  72  is equal to the distance from the root of the guiding tube  71   b  to the mirror  71   c  on the tip of the guiding tube  71   b . As shown in FIGS. 10A and 10B, the heights of the guiding tube  71   b  and the sensor supporter  72  are determined such that the translation region R of the assay plate/support frame is positioned between the guiding tube  71   b  and the sensor supporter  72 . Accordingly, by moving the reagent/sample tray  20 , the assay plate P is guided between the guiding tube  71   b  and the sensor supporter  72 . The light transmitted through each well P 1  is detected with the photodiode  72   a , thereby obtaining the measurement results based on the absorbance.  
     [0099] The slider  78  supports the bracket  75 , and the guiding member  77  is mounted on the base plate  76  along the X-direction. Thus, sliding of the slider  78  can change the detection position by the photodiode  72   a  along the X-direction. The positioning means  79  for moving the slider  78  includes an endless belt  79   c  stretching in the X-direction between a driving pulley  79   a  and a driven pulley  79   b , and a servomotor  79   d  for rotating the driving pulley  79   a . The slider  78  is connected to the center of the endless belt  79   c  via a small bracket  78   a . By rotating the servomotor  79   d , the detection position of the photodiode  72   a  can be positioned along the X-direction via the slider  78  and the bracket  75 . Specifically, the photodiode  72   a  is positioned with respect to each one of wells P 1  lined in the X-direction to measure the absorbance for all of the wells P 1  on that line. Since the assay plate P can travel in the Y-direction by the translation of the reagent/sample tray  20  as described above, this traveling movement and the positioning movement of the photodiode  72   a  in the X-direction can be combined together to determine the absorbance for all of the wells P 1  of the assay plate P.  
     [0100] (Washing Mechanism)  
     [0101] Referring to FIG. 2, the washing mechanism  60  is arranged on the base  11  behind (i.e., upper side in FIG. 2) the photometer  70  in the Y-direction, and adjacent to the support frame  28  side (i.e., right side in FIG. 2) of the reciprocating region of the reagent/sample tray  20 . The washing mechanism  60  will be described with reference to FIGS. 11 and 12. FIG. 11 is a front view of the washing mechanism  60 , and FIG. 12 is a left-side view of the washing mechanism  60  where some parts are omitted. The parts behind a later-described nozzle cover  65  are not shown in FIG. 12.  
     [0102] The washing mechanism  60  is provided with: a main chassis  61  attached to the base  11  (not shown in FIGS. 11 and 12) by four legs  61   a ; a washing manifold  62  including eight sets of washing solution discharging nozzles  62   a  and sucking nozzles  62   b ; a holder  63  for holding the washing manifold  62 ; an elevator  64  for ascending/descending the washing manifold  62  via the holder  63  with respect to the main chassis  61 ; the nozzle cover  65  for receiving drippings from the nozzles  62   a  and  62   b  of the washing manifold  62 ; a washing solution tank (not shown); and washing solution pressure and suction pumps.  
     [0103] The washing manifold  62  has a parallelepiped shape with one set of sides being longer than the other set of sides. The pairs of washing solution discharging nozzles  62   a  and sucking nozzles  62   b  are provided at equal spaces under the washing manifold  62  along the longer sides thereof. The sucking nozzles  62   b  are longer than the washing solution discharging nozzles  62   a . The space between each nozzle is equal to the space between each well P 1  of the assay plate P in the X-direction. The top surface of the washing manifold  62  is provided with a solution supplying port  62   c  communicating with the washing solution discharging nozzles  62   a  and a suction port  62   d  communicating with the sucking nozzles  62   b . The solution supplying port  62   c  is connected to the washing solution pressure pump and a washing solution tank via a hose while the suction port  62   d  is connected to the suction pump via a hose.  
     [0104] The reference numeral  62   e  denotes a bulb which can be opened and closed according to the instruction from the personal computer. While the pumps are generally driven continuously, the washing solution is discharged from the washing solution discharging nozzles  62   a  only when the bulb is opened.  
     [0105] Furthermore, positioning bumps  62   f  and  62   g  are provided in front and back of the washing manifold  62 . The positioning bumps  62   f  and  62   g  are fit into notches formed in the holder  63  to align the washing manifold  62  with respect to the holder  63  in the X-direction.  
     [0106] The main chassis  61  holding the washing manifold  62  via the elevator  64  and the holder  63  is arranged on the base  11  such that the longitudinal side (direction along the lines of the pairs of nozzles) of the washing manifold  62  is parallel to the X-direction, and that the pairs of nozzles are positioned above the respective wells P 1  lined in the X-direction on the assay plate P which moves across the translation region R. To be more specific, the main chassis  61  is arranged such that the pairs of nozzles correspond to the center of the respective wells P 1  in the X-direction.  
     [0107] The elevator  64  includes: a guiding member  64   a  firmly attached to the main chassis  61  in the Z-direction; a slider  64   b  supported by and slidable along the guiding member  64   a ; a screw shaft  64   c  rotatably attached to the main chassis  61  and extending in the Z-direction; and a servomotor  64   b  for rotating the screw shaft  64   c.    
     [0108] The slider  64   b  firmly supports the holder  63  and transmits the ascending/descending movement to the washing manifold  62  via the holder  63 . The slider  64   b  is engaged with the screw shaft  64   c  via a ball screw (not shown), and is ascended or descended according to the rotation of the screw shaft  64   c.    
     [0109] The elevator  64  can adjust the height of the washing manifold  62  to the following three levels; the level where the sucking nozzles  62   b  of the washing manifold  62  are placed separated from and above the assay plate P (state shown in FIGS. 11 and 12, referred to as the set back level); the level where the sucking nozzles  62   b  of the washing manifold  62  stay immediately above the wells P 1  of the assay plate P (referred to as the discharging level); and the level where the tips of the sucking nozzles  62   b  of the washing manifold  62  reach the bottoms of the wells P 1  (referred to as the sucking level). By providing the main chassis  61  with sensors for detecting the slider  64   b  at these levels, a general driving motor can be used instead of the servomotor  64   d  for controlling the rotary amount.  
     [0110] The holder  63  is supported by the slider  64   b  so as to be positioned along the X-direction, with its length generally corresponding to the length of the longitudinal sides of the washing manifold  62 . The holder  63  has a U-shaped section with the top side being open as shown in FIG. 12. The washing manifold  62  is inserted into the space of the holder  63  from the open top. The width of the space of the holder  63  is slightly wider than the thickness of the washing manifold  62  to give a slight play inside the holder  63  supporting the washing manifold  62 . The holder  63  is provided with a spring  63   a  that elastically presses the inserted washing manifold  62 , thereby preventing the washing manifold  62  from moving in the Y-direction. Since the holder  63  supports the washing manifold  62  with the play and the pressure by the spring, the sucking nozzles  62  can make contact with and be pressed against the inner walls of the wells P 1  for sucking operation, thereby effectively removing liquid from the wells P 1 .  
     [0111] The counter planes of the U-shaped sectional holder  63  have notches  63   b  (only one notch being shown) corresponding to the positioning bumps  62   f  and  62   g  of the above-described washing manifold  62 . The notches  63   b  allow each pair of nozzles of the washing manifold  62  to be positioned and fixed in the X-direction.  
     [0112] A contact roller  63   c  for swaying the nozzle cover  65  is provided above the holder  63 . The contact roller  63   c  is ascended/descended according to the movement of the slider  64   b.    
     [0113] As shown in FIG. 12, the nozzle cover  65  is provided with a first arm  65   a  that faces the upper plane of the main chassis  61 ; a second arm  65   b  whose one end is connected to one end of the first arm  65   a ; and a reservoir  65   c  provided at the other end of the second arm  65   b . The first arm  65   a  is connected to the main chassis  61  in the vicinity of its one end capable of swaying with respect to the spindle  65   d  extending in the X-direction. The other end of the first arm  65   a  is provided with a pressure spring  65   e  which separates the first arm  65   a  away from the main chassis  61 .  
     [0114] The second arm  65   b  is connected generally perpendicular to the first arm  65   a . Thus, when the first arm  65   a  is horizontal, the end of the second arm  65   b  points down. In such a state, the reservoir  65   c  is positioned immediately below the nozzles of the washing manifold  62  by slightly being shifted to the right (FIG. 12) from the end of the second arm  65   b . The length of the reservoir  65   c  generally corresponds to the length of the washing manifold  62  in the X-direction, and the reservoir  65   c  is supported by the second arm  65   b  in the X-direction. The bottom of the reservoir  65   c  is slanted in the x-direction such that one end (right end in FIG. 11) is lower than the other. An outlet  65   f  is provided at one end of the reservoir  65   c  to collect and discharged residual liquid dripped from the nozzles  62   a  and  62   b . A waste fluid reservoir (not shown) is provided below the outlet  65   f.    
     [0115] As described above, the levels of the washing manifold  62  and the holder  63  are adjusted among the three levels (i.e., set back level, discharging level and sucking level) by the elevator  64 . The contact roller  63   c  provided on the holder  63  makes contact with the pressure spring having an opposite force such that the first arm  65   a  of the nozzle cover  65  is horizontal at the set back level. Accordingly, when the washing manifold  62  and the holder  63  are descended to the discharging or sucking level, the first arm  65   a  is pressed down by the pressure spring  65   e , by which the reservoir  65   c  is swayed away from the position immediately below the nozzle pairs so as not to interfere with the washing operation.  
     [0116] (Dispensing Mechanism)  
     [0117] Referring to FIG. 2, the dispensing mechanism  40  is arranged on the base  11  behind (i.e., upper side in FIG. 2) the washing mechanism  60  in the Y-direction. The dispensing mechanism  40  includes a dispenser  41  for dispensing the samples and the reagents and a conveyer  90  for transferring the dispenser  41  in the X-direction. FIG. 13 is a plan view of the conveyer  90  and FIG. 14 is a front view of the dispenser  41 . The dispensing mechanism  40  will be described with reference to FIGS. 13 and 14.  
     [0118] As shown in FIG. 13, the conveyer  90  is provided with: an installation stand  91  (see FIGS. 1 and 2) mounted on the base  11  across the translation region of the reagent/sample tray  20  holding the support frame  28 ; a guiding rail  92  mounted on the installation stand  91  in the X-direction; a slider  93  for supporting the dispenser  41  and capable of sliding along the guiding rail  92 ; an endless belt  95  stretching in the X-direction between two driven pulleys  94   a  and  94   b ; a servomotor  96  as a driving source for running the endless belt  95 ; a driving pulley  97  attached to the output axis of the servomotor  96 ; a reduction pulley  98  coaxially connected to the driven pulley  94   a ; and a transmission belt  99  for transmitting torque of the driving pulley  97  to the reduction pulley  98 .  
     [0119] The guiding rail  92  is mounted on the front side of the installation stand  91  in the X-direction. Since the slider  93  is slidable along the guiding rail  92 , the dispenser  41  can be moved to any position along the X-direction. The driven pulleys  94   a  and  94   b  and the endless belt  95  are arranged in the vicinity of the guiding rail  92 . The slider  93  is connected to the center of the endless belt  95  via a bracket  93   a . Thus, by running the endless belt  95 , the dispenser  41  can be aligned along the X-direction via the slider  93 .  
     [0120] The reduction pulley  98  and the driven pulley  94   a  are coaxially supported at both ends of the same axis for an interlocking movement. The diameter of the driving pulley  97  is smaller than that of the reduction pulley  98  so that the rotation speed transmitted to the reduction pulley  98  is reduced. The servomotor  96  can control the rotary amount, by which the dispenser  41  is aligned along the X-direction.  
     [0121] The dispenser  41  includes a dispensing nozzle  45 , and an elevating means for ascending/descending the dispensing nozzle  45  in the Z-direction. The elevating means is provided with: a housing  42  held by the slider  93  of the conveyer  90 ; a guiding member  43  firmly attached to the housing  42  and extending along the Z-direction; a slider  44  for supporting the dispensing nozzle  45  and capable of sliding along the guiding member  43 ; a screw shaft  46  rotationally attached to the housing  42  in the Z-direction; and a servomotor  47  for rotating the screw shaft  46 .  
     [0122] The housing  42  has a parallelepiped shape with one set of sides being longer than the other set of sides. The slider  93  of the conveyer  90  holds the housing  42  such that the longitudinal sides of the housing  42  extend in the Z-direction. The slider  44  of the dispenser  41  is engaged to the screw shaft  46  via a ball screw (not shown), and ascended/descended according to the rotation of the screw shaft  46 . The servomotor  47  can control the rotary amount, by which the dispensing nozzle  45  can be positioned along the Z-direction via the slider  44 .  
     [0123] The dispensing nozzle  45  is a tubular member held by the slider  44  along the Z-direction, with its root end (upper end) being connected to a dispensing pump (not shown) via a hose for suction and discharging. The dispensing pump used should be capable of controlling the sucking and discharging amounts. The tip (bottom end) of the dispensing nozzle  45  has an attachment member  45   a  for attaching a sample tip T 1 , a diluent tip T 2  or a reagent tip T 3 .  
     [0124] The attachment member  45   a  has a small diameter section  45   b  and a large diameter section  45   c  so as to allow any one of the sample tip T 1  and the diluent tip T 2  with small diameters, and the reagent tip T 3  with a large diameter to be attached thereto. As shown in FIG. 15A, the sample tip T 1  or the diluent tip T 2  is attached to the small diameter section  45   b . As shown in FIG. 15B, the reagent tip T 3  is attached to the large diameter section  45   c.    
     [0125] The dispensing nozzle  45  is capable of sliding along the slider  44  in the Z-direction, and is always pressed down by a coil spring  45   d . This structure allows the attachment of the above-described tips T 1 , T 2  and T 3 . Specifically, the tip T 1 , T 2  or T 3  is attached by descending the dispensing nozzles  45  to the tip T 1 , T 2  or T 3  held by the holder  23 ,  24  or  25  with its attachment end facing upward to insert the attachment member  45   a  into the attachment end of the tip. The friction upon the insertion causes an up-directing force on the dispensing nozzle  45 , by which the coil spring  45   d  is pressed up and the dispensing nozzle  45  moves up with respect to the slider  44 . The distance of this upward movement of the dispensing nozzle  45  is detected by a sensor (not shown) to control the slider  44  and the dispensing nozzle  45  until a predetermined distance is obtained for the attachment of the tips T 1 , T 2  and T 3 , thereby allowing uniform attachment of the tips T 1 , T 2  and T 3 . In other words, the tip T 1 , T 2  or T 3  is attached with a preferable strength without being too tight or too loose. As a result, malfunction such as undesirable disconnection or being unable to take off the tip by too tight connection can be prevented.  
     [0126] (Tip Disposing Unit)  
     [0127] Referring to FIG. 2, a tip disposing unit  13  is arranged at the end (i.e., right side in FIG. 2) of the region where the dispensing portion  41  is carried by the conveyer  90  of the dispensing mechanism  40 . The tip disposing unit  13  will be described with reference to FIGS. 16A and 16B. FIGS. 16A and 16B are a perspective view and a front view of the tip disposing unit, respectively.  
     [0128] The tip disposing unit  13  is provided with a collecting receptacle  13   a  for collecting the disposed tips T 1 , T 2  and T 3 , and a tip catch  13   b  attached to the upper end of the collecting receptacle  13   a . The upper end of the tip catch  13   b  is bent toward the dispenser  41  (to the left in FIG. 2) and is provided with a notch  13   c  having two width sizes.  
     [0129] The notch  13   c  is positioned in the middle of the path of the dispensing nozzle  45  transferred by the conveyer  90 . The narrow part  13   d  of the notch  13   c  is wider than the diameter of the small diameter section  45   b  of the dispensing nozzle  45  and narrower than the diameter of the attachment ends of the tips T 1  and T 2 . The wide part  13   e  is wider than the diameter of the large diameter section  45   c  of the dispensing nozzle  45  and narrower than the diameter of the attachment end of the tip T 3 .  
     [0130] Disconnection of the sample tip T 1  by the tip disposing unit  13  will be described. First, the dispensing nozzle  45  with the sample tip T 1  being attached thereto is transferred to the tip disposing unit  13 . The notch  13   c  of the tip catch  13   b  is aligned in the tip disposing unit  13 . And the height of the dispensing nozzle  45  is adjusted in advance such that the part of the small diameter section  45   b  where it is not covered with the sample tip T 1  (part of the small diameter section  45   b  in the vicinity of the boundary with the large diameter section  45   c ) is inserted into the notch  13   c . The dispensing nozzle  45  is conveyed until the small diameter section  45   b  fits into the narrow part  13   d  of the notch  13   c . By moving the dispensing nozzle  45  upward, only the sample tip T 1  is caught by the tip catch  13   b , disconnected from the attachment member  45   a  of the dispensing nozzle  45  and disposed in the collecting receptacle  13   a.    
     [0131] The diluent tip T 2  can also be disconnected in exactly the same manner. In the case of the reagent tip T 3 , the part above the large diameter section  45   c  of the dispensing nozzle  45  is adjusted to the height of the notch  13   c . The dispensing nozzle  45  is conveyed until the large diameter section  45   c  thereof fits into the wide part  13   e  of the notch  13   c . Thereafter, the dispensing nozzle  45  may be moved upward.  
     [0132] (Plate Cover)  
     [0133] Referring to FIG. 2, the plate cover  12  for covering the top surface of the assay plate P held on the support frame  28  is generally formed over the entire translation region of the assay plate P defined by the movement of the reagent/sample tray  20 . FIG. 17 is a schematic view for illustrating a positional relationship between the plate cover  12  and the assay plate P held on the support frame  28 . FIG. 18 is a perspective view showing the plate cover  12 . The plate cover  12  will be described with reference to FIGS. 17 and 18.  
     [0134] As shown in FIG. 18, the plate cover  12  has a flat board-like shape and is arranged with its longitudinal sides extending along the Y-direction between the temperature maintaining mechanism  50  and the power source  14 . As shown in FIG. 17, the plate cover  12  is formed slightly wider than the width of the assay plate P in the X-direction, with the both sides being bent toward the assay plate P. The flat plane of the plate cover  12  is supported by the temperature maintaining mechanism  50  and the power source  14  such that it is parallel to and in the vicinity of the top surface of the assay plate P on the support frame  28 .  
     [0135] The assay plate P is transferred to positions within the translation region, where the wells P 1  thereof are subjected to the reaction determination, washing and dispensing of the sample/reagent. Since all of these operations are performed from above the assay plate P, the plate cover  12  is provided with openings for each operation. Specifically, openings  12   a ,  12   b  and  12   c  are provided corresponding to the positions of the photometer  70 , the washing mechanism  60  and the dispensing mechanism  40 , respectively. Each of the openings  12   a ,  12   b  and  12   c  extends for almost the whole width of the plate cover  12  in the X-direction. Thus, the plate cover  12  can cover all of the wells P 1  while they are transferred or cover part of the wells P 1  waiting for the operations without interfering with the operations, thereby effectively preventing evaporation of the moisture of the sample or the reagent contained in the open wells P 1 .  
     [0136] (Description of the Operation of the Enzyme Immunoassaying Apparatus)  
     [0137] The operation of the enzyme immunoassaying apparatus  10  will be described with reference to FIGS. 2 and 19. FIG. 19 is a flowchart showing the sequential steps of the operation of the enzyme immunoassaying apparatus  10 . Hereinafter, for convenience&#39;s sake, the upward direction in FIG. 2 is referred to as the proceeding direction, the downward direction as the returning direction, and the right and left directions as the same.  
     [0138] The operation of the enzyme immunoassaying apparatus  10  described below is implemented by programs executed by the above-described personal computer for controlling the operation of the enzyme immunoassaying apparatus  10 .  
     [0139] First, as a preparatory arrangement, the assay plate P and the dilution plate U are mounted on the hollows  28   a  and  28   b  of the support frame  28 , respectively. The assay plate P is mounted on the support frame  28  inside the temperature maintaining mechanism  50 .  
     [0140] The reagent bottles S used for the assay and the diluent bottles are set into the reagent stock unit  21  on the reagent/sample tray  20 , and the reagent tips T 3  into the reagent tips stock unit  25 . Furthermore, the sample tips stock unit  23  with the sample tips T 1 , the diluent tips stock unit  24  with the diluent tips T 2  and the sample stock unit  22  with the sample containers K are set at respective positions on the reagent/sample tray  20 .  
     [0141] After the preparatory arrangement, the operation of the enzyme immunoassaying apparatus  10  is initiated. First, the sample is diluted. Specifically, a diluent is dispensed into the wells U 1  of the dilution plate U (Step S 1 ) by using the reagent tip T 3 . The reagent tip T 3  is used by positioning the dispensing nozzle  45  above a tip of the reagent tips stock unit  25  by the cooperation of the stage mechanism  30  and the conveyer  90  of the dispensing mechanism  40  and descending the dispensing nozzle  45  by the elevating means and the reagent tip T 3  is attached.  
     [0142] Next, the dispensing nozzle  45  is positioned and descended to the diluent bottle held in the reagent stock unit  21  to suck a predetermined amount of the diluent with the reagent tip T 3  by activating the dispensing pump.  
     [0143] The dilution plate U is sent to the operation region of the dispensing nozzle  45  by the stage mechanism  30 . The dilution plate U is aligned such that the front-most row of wells U 1  in the proceeding direction is positioned on the operation region of the dispensing nozzle  45 . The dispensing nozzle  45  is positioned above the right-most well U 1  in the front-most row of the dilution plate U by the conveyer  90  and descended to the discharging level to discharge the diluent. The dispensing nozzle  45  is sent to the left for dispensing the diluent into the rest of the wells U 1  in that row in the X-direction in the same manner. After the diluent is dispensed into the wells U 1  in the front-most row, the dilution plate U is sent to the proceeding direction for a line of wells U 1  in the Y-direction by the stage mechanism  30  to perform the dispensing operation in the same manner.  
     [0144] Since the amount of the diluent to be discharged for each well U 1  is predetermined based on the dilution ratio, the amount of the diluent in the reagent tip T 3  as to the number of wells it can fill can be calculated. Thus, if necessary, the reagent tip T 3  may appropriately be refilled with the diluent during the course of the dispensing operation for the dilution plate U.  
     [0145] Once the diluent is dispensed into all of the wells U 1 , the dispensing nozzle  45  is carried to the disposing member  13 , where the reagent tip T 3  is disposed.  
     [0146] Then, the sample is dispensed into each well U 1 . First, the dispensing nozzle  45  is sent to the sample tip holder  26  by the cooperation of the stage mechanism  30  and the conveyer  90 , and a sample tip T 1  at one of the tip positions is attached. After the attachment of the tip, the dispensing nozzle  45  is sent to the sample stock unit  22 , where it is aligned with one of the sample containers K to suck a predetermined amount of the sample. The sample tip T 1  and the sample container K may be selected in a sequential manner starting from the right-most ones in the front-most row.  
     [0147] After the suction of the sample, the dispensing nozzle  45  discharges the sample into the dilution plate U. The sample is discharged into the right-most well U 1  in the front-most row, after which the sample tip T 1  is disposed at the disposing member  13 . Samples are discharged into the corresponding wells U 1  in the similar manner.  
     [0148] After the samples are completely discharged into the wells U 1  of the dilution plate U, the vibrating mechanism  80  is operated for a predetermined period of time to shake the wells U 1  (Step S 2 ).  
     [0149] On the other hand, a predetermined amount of diluent is dispensed into each of the wells P 1  of the assay plate P (Step S 3 ). The dispensing operation of the diluent is conducted in the same manner as Step S 1 . Specifically, the dispensing nozzle  45  is attached with the reagent tip T 3 , used to suck the diluent and is aligned to each well P 1  to discharge the diluent. Thereafter, the reagent tip T 3  is disposed.  
     [0150] Next, the diluted samples in the wells U 1  of the dilution plate U are transferred to the corresponding wells P 1  of the assay plate P (Step S 4 ). Specifically, steps of attaching the diluent tip T 2 , sucking a predetermined amount of sample from the well U 1 , discharging the sample into the corresponding well P 1  of the assay plate P and disposing the used tip are repeated for every well U 1 . Accordingly, each sample is further diluted.  
     [0151] Then, the assay plate P is sent to the temperature maintaining mechanism  50  by the stage mechanism  30 . At the temperature maintaining mechanism  50 , the assay plate P is kept at a preferable temperature by the heater  51 . The assay plate P is shaken by the vibrating mechanism  80  in order to equalize the reaction of the reagent pre-applied in the assay plate P with each sample, or to stimulate the reaction. This shaking may take place outside the temperature maintaining mechanism  50  (Step S 5 ) by transferring the assay plate P by the stage mechanism  30 .  
     [0152] After heating with the temperature maintaining mechanism  50  for a predetermined period of time, each well P 1  of the assay plate P is washed (Step S 6 ). The wash bath  29  provided on the support frame  28  is transferred by the stage mechanism  30  and positioned immediately below the line of the nozzle pairs of the washing mechanism  60 . The washing manifold  62  is descended from the set back level to the sucking level at once to connect the washing solution discharging nozzle  62   a  to the operating washing solution pressing pump and the sucking nozzle  62   b  to the operating suction pump. Accordingly, the washing solution is discharged into the wash bath  29  and sucked as the tip of the sucking nozzle  62   b  is washed. After a predetermined period of time, the washing solution discharging nozzle  62   a  is disconnected from the pump, and thereafter, the sucking nozzle  62   b  is disconnected from the pump. In this manner, the washing solution in the wash bath  29  is completely sucked. The washing manifold  62  returns to the set back level.  
     [0153] Next, the assay plate P is conveyed to the washing mechanism  60  by the stage mechanism  30 . The wells P 1  in the front-most row (in the proceeding direction) of the assay plate P are positioned immediately below the pairs of nozzles of the washing mechanism  60 . Then, the washing manifold  62  is descended from the set back level to the sucking level to connect the sucking nozzles  62   b  to the suction pump under operation, thereby sucking the samples from the wells P 1  in the front-most row. Then, the washing manifold  62  is ascended to the discharging level to discharge the washing solution from the washing solution discharging nozzles  62   a . The washing manifold  62  is again descended to the sucking level to suck the washing solutions from the wells P 1 . After repeating these washing solution discharging and sucking steps for predetermined times, the washing manifold  62  returns to the set back level. The stage mechanism  30  sends the assay plate P to target the next row of wells to perform the same washing process. The washing operation is performed for every row, thereby washing all of the wells P 1  of the assay plate P.  
     [0154] Although the sample in each well P 1  is washed away by the washing operation, the sample has already soaked into the reagent pre-applied in each well P 1  and thus no influence is caused upon the later-performed determination.  
     [0155] Next, a first reagent (an enzyme-labeled antibody solution) is dispensed into the wells P 1  of the assay plate P (Step S 7 ). This dispensing operation of the first reagent is performed in the similar manner to that for the diluent in Step S 3 . Specifically, the dispensing nozzle  45  is attached with a reagent tip T 3  to suck the first reagent, aligned with the wells P 1  to discharge the first reagent. Thereafter, the reagent tip T 3  is disposed.  
     [0156] The assay plate P with the first reagent is shaken and heated in the same manner as Step S 5  (Step S 8 ). After keeping at a predetermined temperature for a predetermined period of time, the wells P 1  are washed inside by the same operation as Step S 6  (Step S 9 ).  
     [0157] After washing the first reagent away, a second reagent (color developing substrate) is dispensed in generally the same manner as Step S 7  (Step S 10 ), followed by shaking and heating in the same manner as Step S 8  (Step S 11 ).  
     [0158] After keeping at a predetermined temperature for a predetermined period of time, a third reagent (stop solution) is dispensed into the wells P 1  of the assay plate P in the same manner as Step S 7  (Step S 12 ).  
     [0159] Once the third reagent is dispensed, absorbance of each well P 1  is determined for enzyme immunoreaction assay (Step S 13 ). The absorbance is determined by the photometer  70 . As a preparatory arrangement for the photometer  70 , a light beam radiated from the halogen lamp  71   a  is received by the photodiode  72   a  under a condition where nothing is present between the radiation unit  71  and the sensor supporter  72 , with the throughhole  73   b  being selected by the filter selecting means  74 . The sensor output in this state is stored in the personal computer as a blank data for correcting the measurement data afterwards.  
     [0160] Next, wells P 1  in the front-most row of the assay plate P in the proceeding direction are positioned between the radiation unit  71  and the sensor supporter  72  by the stage mechanism  30 . The filter selecting means  74  selects the band pass filter  73   a  suitable for the measurement. The positioning means  79  positions the slider  78  such that the photodiode  72   a  stays immediately below the well P 1  at the right end.  
     [0161] Then, the halogen lamp  71   a  is switched on and the light transmitted from the well P 1  is detected by the photodiode  72   a , thereby determining the absorbance. The positioning means  79  sends the slider  78  to the left for a single well P 1  for determining the absorbance of the next well P 1 . After determining the absorbance for all of the wells P 1  in the front-most row, the stage mechanism  30  conveys the assay plate P to the next row. By repeating these steps, absorbance is determined for all of the wells P 1  of the assay plate P.  
     [0162] All of the results from the above-described measurement are stored in the personal computer, where the above-mentioned blank data is used for correction, thereby obtaining correct measurement results.  
     [0163] As described above, the reagent/sample tray  20 , the stage mechanism  30  for conveying the reagent/sample tray  20 , the dispensing mechanism  40  for dispensing the samples and the reagents, the temperature maintaining mechanism  50  for heating the assay plate P, the washing mechanism  60  for washing the wells P 1 , the photometer  70 , and the vibrating mechanism  80  for shaking the assay plate P are assembled in a single device, the enzyme immunoreaction assaying apparatus  10 . Therefore, a series of operations including the dispensing operations for a plurality of samples and reagents, and the heating, washing, shaking and reaction determining operations for the assay plate P can be automated, which has conventionally been considered difficult.  
     [0164] The assay plate P can be conveyed by the stage mechanism  30  to any one of the dispensing mechanism  40 , the temperature maintaining mechanism  50 , the washing mechanism  60  and the photometer  70  because the dispenser  41  of the above-described dispensing mechanism  40  can move reciprocally in a direction perpendicular to the reciprocating region of the reagent/sample tray  20  and because the temperature maintaining mechanism  50 , the washing mechanism  60  and the photometer  70  are arranged on the reciprocating region of the reagent/sample tray  20  and are adjacent to the support frame  28  that is provided at the end of the reagent/sample tray  20 . Thus, there is no need of providing individual conveying mechanisms for the reagent/sample tray  20  and for the assay plate P, thereby reducing the number of parts required for producing the apparatus. As a result, the productivity is enhanced, and the apparatus can be made smaller and lighter.  
     [0165] Since the conveyer  90  of the dispensing mechanism  40  transfers the dispenser  41  in the direction perpendicular to the reciprocating direction of the reagent/sample tray  20 , the positioning of the dispensing nozzle  45  with respect to the reagent/sample tray  20  and the assay plate P can easily be calculated based on the rectangular coordinates system.  
     [0166] Furthermore, since the support frame  28  is protruding from the end of the reagent/sample tray  20  while the part of the housing  52  of the temperature mechanism  50  is notched where it overlaps with the translation region R of the assay plate/support frame, the assay plate P and the support frame  28  can be conveyed inside the housing  52  of the temperature maintaining mechanism  50  upon transferring the reagent/sample tray  20 . Thus, for the temperature maintaining operation, there is no need of providing individual mechanisms for placing and removing the assay plate P in and from the temperature maintaining mechanism  50 , thereby reducing the number of parts required for producing the apparatus. As a result, the productivity is enhanced, and the apparatus can be made smaller and lighter.  
     [0167] In the enzyme immunoassaying apparatus  10 , the vibrating mechanism  80  for shaking the assay plate P via the support frame  28  is provided on the reagent/sample tray  20 . Accordingly, there is no need of providing an independent conveying means for conveying the assay plate P to the vibrating mechanism  80 , thereby reducing the number of parts required for producing the apparatus. As a result, the productivity is enhanced, and the apparatus can be made smaller and lighter.  
     [0168] Moreover, the support frame  28  is provided with the hollows  28   a  and  28   b  for arranging the assay plate P and the dilution plate U therein, respectively. Accordingly, dilution to a lower concentration can be performed on the dilution plate U followed by further dilution on the assay plate P. The assay plate P and the dilution plate U can be shaken at the same time via the support frame  28 , thereby reducing the time required for the operations. Since there is no need of providing an independent vibrating mechanism for the dilution plate U, the number of parts required for producing the apparatus can be reduced. As a result, the productivity is enhanced, and the apparatus can be made smaller and lighter.  
     [0169] The invention of claim  1  comprises: a tray conveying mechanism for conveying a sample/reagent tray; a dispensing mechanism for dispensing a sample or a regent into a microplate having a plurality of reaction wells; and a temperature maintaining mechanism for the microplate. As a result, a sample assaying apparatus is provided which can automatically perform a plurality of operations including dispensing a plurality of samples and reagents into a microplate, and heating the microplate.  
     [0170] The microplate can be conveyed by the tray conveying mechanism to either one of the dispensing mechanism and the temperature maintaining mechanism because the dispenser of the dispensing mechanism can move reciprocally in a direction perpendicular to the reciprocating region of the reagent/sample tray and because the temperature maintaining mechanism is arranged on the reciprocating region of the reagent/sample tray and is adjacent to the microplate supporter that is provided at the end of the reagent/sample tray. Thus, there is no need of providing individual conveying mechanisms for the reagent/sample tray and for the microplate, thereby reducing the number of parts required for producing the apparatus. As a result, the productivity is enhanced, and the apparatus can be made smaller and lighter.  
     [0171] According to claim  2  of the invention, the conveyer of the dispensing mechanism transfers the dispenser in the direction perpendicular to the reciprocating direction of the reagent/sample tray. Thus, the positioning of the dispenser with respect to the reagent/sample tray and the microplate can easily be calculated based on the rectangular coordinates system.  
     [0172] According to the invention of claim  3 , a sample assaying apparatus can be provided which can carry out a washing operation in addition to the above-mentioned operations by further comprising a washing mechanism for washing the microplate, wherein the washing mechanism is arranged adjacent to the microplate-supporter side of the reciprocating region of the reagent/sample tray. Since the microplate can be sent to the washing mechanism by transferring the reagent/sample tray, there is no need of providing an independent conveying mechanism for conveying the microplate to the washing mechanism, thereby reducing the number of parts required for producing the apparatus. As a result, the productivity is enhanced, and the apparatus can be made smaller and lighter.  
     [0173] According to the invention of claim  4 , a sample assaying apparatus can be provided which can carry out a reaction determining operation in addition to the above-mentioned operations by further comprising a photometer arranged adjacent to the microplate-supporter side of the reciprocating region of the reagent/sample tray. Since the microplate can be sent to the photometer by transferring the reagent/sample tray, there is no need of providing an independent conveying mechanism for conveying the microplate to the photometer, thereby reducing the number of parts required for producing the apparatus. As a result, the productivity is enhanced, and the apparatus can be made smaller and lighter.  
     [0174] According to the invention of claim  5 , the microplate supporter is protruding from the end of the reagent/sample tray while the part of the housing of the temperature mechanism is notched where it overlaps with the translation region of the microplate/supporter. Thus, the microplate and the supporter can be conveyed inside the housing of the temperature maintaining mechanism by transferring the reagent/sample tray. Accordingly, for the temperature maintaining operation, there is no need of providing individual mechanisms for placing and removing the microplate in and from the temperature maintaining mechanism, thereby reducing the number of parts required for producing the apparatus. As a result, the productivity is enhanced, and the apparatus can be made smaller and lighter.  
     [0175] According to the invention of claim  6 , the microplate supporter is formed as a frame so as to hold the microplate with the top and back surfaces thereof being exposed. At the same time, the temperature adjuster of the temperature maintaining mechanism is provided beneath the microplate while a lid is provided above the microplate. Thus, the temperature of the microplate can efficiently be adjusted from the exposed back surface of the microplate while the moisture contained in the reaction vessels can be prevented from evaporating upon the temperature adjustment.  
     [0176] According to the invention of claim  7 , a sample assaying apparatus is provided which can carry out an shaking operation in addition to the above-mentioned operations by further comprising a vibrating mechanism for shaking the microplate via the supporter on the reagent/sample tray. Since the vibrating mechanism shakes the microplate via the supporter, there is no need of providing an independent conveying means for conveying the microplate to the vibrating mechanism, thereby reducing the number of parts required for producing the apparatus. As a result, the productivity is enhanced, and the apparatus can be made smaller and lighter.  
     [0177] According to the invention of claim  8 , the supporter is provided with regions for arranging the microplate and a dilution plate therein. Accordingly, dilution to a lower concentration can be performed on the dilution plate followed by further dilution on the microplate. In addition, the microplate and the dilution plate can be shaken at the same time via the supporter, thereby reducing the time required for the operations. Since there is no need of providing an independent vibrating mechanism for the dilution plate, the number of parts required for producing the apparatus can be reduced. As a result, the productivity is enhanced, and the apparatus can be made smaller and lighter.  
     [0178] As described above, the present invention provides a sample assaying apparatus, which is superior over conventional apparatuss.  
     [0179] The invention may be embodied in other specific forms without departing from the spirit or essential characteristic thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.  
     [0180] The entire disclosure of Japanese Patent Application No. 2000-212363 (Filed on Jul. 13, 2000) including specification, claims, drawings and summary are incorporated herein by reference in its entirety.