US20020090321A1 - Incubator - Google Patents

Abstract

An incubator includes a rotating incubator rotor. The incubator rotor is provided with a plurality of element chambers which are arranged along the outer periphery of the incubator rotor and each of which accommodates a dry analysis element spotted with a sample and incubates the dry analysis element. A light measuring system has a light measuring head which measures the optical density of the dry analysis element. The light measuring system is provided with a correction system which compensates for fluctuation in the value of the optical density of the dry analysis element in each of the element chambers as measured by the light measuring head generated due to fluctuation in the distance between the light measuring head and the element chamber on the basis of a correction value which has been stored in the correction system element chamber by element chamber.

Description

FIELD OF THE INVENTION
• This invention relates to an incubator which is used in a biochemical analysis system, in which a sample such as blood or urine is spotted onto a dry analysis element and, for instance, the concentration of a specific biochemical component contained in the sample is detected, to keep the dry analysis element at a constant temperature in order to measure change of the optical density.[0001]
DESCRIPTION OF THE RELATED ART
• Recently, there has been put into practice a colorimetric dry (dry-to-the touch) analysis element with which the content of a specific biochemical component or a specific solid component contained in a sample liquid can be quantitatively analyzed by simply spotting a droplet of the sample liquid. Since being capable of analyzing samples easily and quickly, the biochemical analysis systems using such dry analysis elements are suitably used in medical institutions, laboratories and the like.[0002]
• When quantitatively analyzing the chemical components or the like contained in a sample liquid using such a colorimetric dry analysis element, a droplet of the sample liquid is spotted on the analysis element, and the analysis element is held at a constant temperature for a predetermined time in an incubator so that a coloring reaction (pigment forming reaction) occurs, and the optical density of the color formed by the coloring reaction is optically measured. That is, measuring light containing a wavelength which is pre-selected according to the combination of the component to be analyzed and the reagent contained in the analysis element is projected onto the analysis element and the optical density of the analysis element is measured. Then the concentration of the component to be analyzed is determined on the basis of the optical density according to a calibration curve representing the relation between the concentration of the specific biochemical component and the optical density.[0003]
• When the distance between the dry analysis element and the light measuring head (a head for projecting said measuring light onto the dry analysis element and receives light from the dry analysis element bearing thereon the optical density of the dry analysis element fluctuates, there can be produced measuring errors since the light measuring head has own optimal measuring distance due to its light measuring sensitivity properties as will be described later in conjunction with FIG. 4. In order to accurately measure the concentration of a specific component in the sample, it is necessary to detect even a slight coloring reaction and it is required for the colorimetry to be carried out at a high accuracy. Accordingly, it is important to keep constant the distance between the dry analysis element and the light measuring head.[0004]
• In Japanese Patent Publication No. 5(1993)-72976, the optical components of the light measuring head are positioned where the output of the light measuring head is maximized, so that the influence of variation of the distance on the light measuring sensitivity is minimized.[0005]
• In U.S. Pat. No. 5,037,613, there is disclosed a structure in which the lower surface of the outer periphery of the incubator rotor, which is rotated with dry analysis elements spotted with the samples accommodated therein, is supported by a sliding support so that the rotational displacement of the incubator rotor is suppressed and the distance between the light measuring head and each of the dry analysis elements arranged along the outer periphery of the incubator rotor is held constant.[0006]
• However, the approach disclosed in the aforesaid Japanese patent publication is disadvantageous in that though fluctuation of the distance can be held in an acceptable range where the influence of variation of the distance on the light measuring sensitivity can be suppressed by the arrangement of the optical components so long as the diameter of the incubator rotor is small and the rotational displacement of the incubator rotor is small, fluctuation of the distance becomes too large for the optical components to suppress the influence of variation of the distance on the light measuring sensitivity in an acceptable range when the number of the dry analysis elements to be accommodated in the incubator increases and the diameter of the incubator rotor increases. An attempt to limit the rotational displacement of a large incubator rotor increases requirement on processing accuracy and fabricating accuracy of the components of the incubator rotor, thereby adding to the manufacturing cost of the incubator.[0007]
• The approach disclosed in the United states patent is disadvantageous in that as the sliding support wears, the rotational displacement of the incubator rotor increases and the incubator rotor drive mechanism can become unstable due to nonuniform load and wear of the sliding support will produce dust.[0008]
• Displacement in height of the incubator rotor relative to the measuring head during rotation of the incubator rotor is generated by strain generated when forming the rotor and/or strain generated when mounting the rotor on the rotating shaft. Accordingly, the distance between the measuring head and each of the element chambers arranged along the outer periphery of the incubator rotor when the element chamber is brought to a predetermined position, e.g., a light measuring position where the optical density of the dry analysis element is to be measured, is constant for each element chamber but differs from chamber to chamber. As the difference in the distance between the measuring head and the element chambers increases, variation in the measured value for a given optical density becomes larger.[0009]
• As disclosed, for instance, in Japanese Unexamined Patent Publication No. 11(1999)-237386, there has been known an incubator provided at its center with an element discarding hole through which dry analysis elements after measurement are discarded by pushing the dry analysis elements further inward by the element transfer member which pushes the dry analysis elements into the element chambers of the incubator. This structure is advantageous in that the dry analysis elements can be easily discarded with the transfer mechanism of a simple structure.[0010]
• However, as the number of the dry analysis elements to be accommodated in the incubator increases and the diameter of the incubator rotor increases, the diameter of the discarding hole must be large in order to discard the dry analysis elements in all the element chambers by a limited stroke of the element transfer member. When the diameter of the discarding hole is enlarged and the diameter of the rotating shaft of the incubator rotor is increased, the diameter of the bearing member for supporting the rotating shaft must be large, which adds to the manufacturing cost of the bearing member. Especially when the bearing member must support the rotating shaft of the incubator rotor so as to suppress the rotational displacement of the incubator rotor in the acceptable range as described above, the manufacturing cost of the bearing member is further increased.[0011]
• On the other hand, when the diameter of the element discarding hole is reduced, the distance over which the dry analysis elements are conveyed to be discarded becomes longer, which adds to the length and stroke of the element transfer member and increases the overall size and weight of the apparatus.[0012]
SUMMARY OF THE INVENTION
• In view of the foregoing observations and description, the primary object of the present invention is to provide an incubator which can accurately measure the optical density of the dry analysis element in all the element chambers of the incubator without using a sliding support and can be manufactured at low cost even if it is provided with a large number of element chambers and is large in size.[0013]
• Another object of the present invention is to provide an incubator which is precise in rotation and small in weight and in which the dry analysis elements can be easily discarded after measurement.[0014]
• The first object of the present invention can be accomplished by an incubator comprising a rotating incubator rotor provided with a plurality of element chambers which are arranged along the outer periphery of the incubator rotor and each of which accommodates a dry analysis element spotted with a sample and incubates the dry analysis element and a light measuring means having a light measuring head which measures the optical density of the dry analysis element, wherein the improvement comprises that[0015]
• the light measuring means is provided with a correction means which compensates for fluctuation in the value of the optical density of the dry analysis element in each of the element chambers as measured by the light measuring head generated due to fluctuation in the distance between the light measuring head and the element chamber on the basis of a correction value which has been stored in the correction means element chamber by element chamber.[0016]
• It is preferred that the correction means sets the correction value for each element chamber by inserting a calibration element whose optical density is known into each of the element chambers of the incubator rotor, measuring the optical density of the calibration element with the light measuring head and determining the correction value for the element chamber on the basis of the difference between the known optical density of the calibration element and the measured optical density of the same.[0017]
• In the incubator of this invention, since the measured value of the optical density of the dry analysis element in each element chamber is corrected on the basis of a correction value which is set according to the position of the element chamber, i.e., the distance between the light measuring head and the element chamber in which the dry analysis element is accommodated, the optical density can be accurately measured for each element chamber even if the distance between the light measuring head and each of the element chambers of the incubator fluctuates chamber to chamber. Accordingly, the incubator rotor need not be so precisely manufactured and the sliding support becomes unnecessary, whereby the incubator can be easily manufactured at low cost and the durability of the incubator is increased.[0018]
• When the correction means sets the correction value for each element chamber by inserting a calibration element whose optical density is known into each of the element chambers of the incubator rotor, measuring the optical density of the calibration element with the light measuring head and determining the correction value for the element chamber on the basis of the difference between the known optical density of the calibration element and the measured optical density of the same, setting of the correction value is facilitated.[0019]
• That is, though the incubator rotors rotate in different ways according to the processing accuracy and the like and the distance between the light measuring head and each of the element chambers in the measuring position to which the element chambers are brought in sequence as the incubator rotor rotates differs element chamber to element chamber, the optical density can be accurately measured for each element chamber irrespective of fluctuation in distance between the light measuring head and the element chamber by correcting the measured value for each element chamber on the basis of a correction value determined for each element chamber according to the real distance between the light measuring head and the element chamber. The correction value for each element chamber can be easily set by reading the measurement for a calibration element whose optical density is known and determining the correction value on the basis of the difference between the known optical density and the measured value.[0020]
• The second object of the present invention can be accomplished by an incubator comprising a rotating incubator rotor provided with a plurality of element chambers which are arranged along the outer periphery of the incubator rotor and each of which accommodates a dry analysis element spotted with a sample and incubates the dry analysis element, wherein the improvement comprises that[0021]
• the incubator rotor is provided with a cone-like slant surface which is formed below the element chambers and tapers downward toward the axis of rotation of the incubator rotor, a cylindrical rotating shaft which is connected to the lower end of the slant surface and the inner space of which opens to the space defined by the cone-like slant surface so that the dry analysis element in each element chamber can be discarded outside the incubator through the space defined by the cone-like slant surface and the inner space of the cylindrical rotating shaft and a bearing member which supports the cylindrical rotating shaft for rotation about the axis of rotation of the incubator rotor.[0022]
• It is preferred that the slant surface be at an angle not smaller than 30° to the horizontal so that the dry analysis element is surely slid on the slant surface toward the cylindrical rotating shaft.[0023]
• In the incubator of this arrangement, the rotating shaft need not be large in diameter even if the number of the dry analysis elements to be accommodated in the incubator increases and the diameter of the incubator rotor increases, and accordingly, the bearing member may be small in diameter, whereby the incubator can be manufactured at low cost. Further, since the dry analysis elements after measurement can be discarded by pushing the dry analysis elements only to the slant surface, the stroke of the element transfer member need not be enlarged even if the number of the dry analysis elements to be accommodated in the incubator increases and the diameter of the incubator rotor increases, whereby the incubator can be small in size and weight.[0024]
• Further by virtue of the member defining the cone-like slant surface, rigidity of the incubator rotor is increased and the incubator rotor can be rigid enough though it is small in weight, whereby wobbling of the incubator rotor can be suppressed without use of a sliding support and the measuring accuracy can be enhanced.[0025]
• The incubator can be employed to incubate various types of dry analysis element without limited to the colorimetric dry analysis element. For example, the incubator can be employed to incubate electrolytic dry analysis elements for measuring the activity of a specific ion contained in a sample liquid.[0026]
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a perspective view showing a biochemical analysis system provided with an incubator in accordance with an embodiment of the present invention,[0027]
• FIG. 2 is a schematic cross-sectional view showing the incubator with the cover removed,[0028]
• FIG. 3 is a block diagram showing the measuring mean,[0029]
• FIG. 4 is a view for illustrating change of the sensitivity of the light measuring head with the distance between the element chamber and the light measuring head,[0030]
• FIG. 5 is a view showing correction value properties, and[0031]
• FIG. 6 is a cross-sectional view showing an incubator in accordance with another embodiment of the present invention.[0032]
DESCRIPTION OF THE PREFERRED EMBODIMENT
• In FIG. 1, a biochemical analysis system[0033]1 comprises asystem body17 and acircular sample tray2 is provided on one side of the front portion of thesystem body17. Acircular incubator3 is provided on the other side of the front portion of thesystem body17, and a spotting station (not shown) is provided between thesample tray2 and theincubator3. Further aspotting nozzle unit5 is provided on an upper portion of thesystembody17 to be movable right and left. Adry analysis element11 held in asample cartridge7 is moved to the spotting station and spotted with a sample. Then thedry analysis element11 spotted with the sample is transferred to theincubator3. A blood filtering unit6 for separating blood plasma from blood is provided beside thesample tray2.
• The[0034]incubator3 comprises anincubator rotor30 and a measuring means4. Theincubator rotor30 comprises lower andupper disc members31 and32, and a plurality ofelement chambers33 in which thedry analysis elements11 are inserted are formed between the lower andupper disc members31 and32 arranged along the circumference of thedisc members31 and32 at regular intervals.
• A rotating[0035]shaft36 extends downward at the center of thelower disc member31 and the rotatingshaft36 is supported for rotation by abearing member37 so that thelower disc member31 is rotated horizontally about the rotatingshaft36. A sprocket36sis fixed to the lower end portion of the rotatingshaft36 and in mesh with adrive gear38afixed to the output shaft of adrive motor38 so that theincubator rotor30 is rotated in the regular direction and the reverse direction by thedrive motor38.
• Sliding[0036]holes32aare formed in theupper disc member32 to be opposed to theelement chambers33. A pressingmember34 is disposed above eachelement chamber33 with its upper portion slidably received in thesliding hole32a. The lower surface of the pressingmember34 presses downward thedry analysis element11 inserted into theelement chamber33 and tightly closes the spotting hole of the dry analysis element11 (through which the sample is spotted onto the element11) to prevent evaporation thereof. The outer edge of the lower portion of the pressingmember34 is tapered so that thedry analysis element11 inserted into theelement chamber33 is brought into abutment against the tapered surface to push upward the pressingmember34.
• A[0037]heater35 is provided in theupper disc member32 to heat thedry analysis elements11 in theelement chambers33. By controlling theheater36, the dry analysis elements can be held at a desired constant temperature (incubated).
• A[0038]light measuring window31ais formed in the bottom of thelower disc member31 opposed to each of theelement chambers33. Alight measuring head41 is positioned below thelight measuring window31aof theelement chamber33 stopped in a light measuring position shown in FIG. 2. Though not shown, theincubator rotor30 is covered with a cover in order to cut influence of the ambient temperature to thedry analysis elements11 and to prevent external light from impinging upon thelight measuring head41.
• The[0039]incubator rotor30 is rotated back and forth so that theelement chambers33 are brought to the light measuring position in sequence and returned to the initial position after measurement of the optical density of eachdry analysis element11 due to the coloring reaction.
• When the optical density is measured, the[0040]light measuring head41 projects measuring light containing a wavelength which is pre-selected according to the combination of the component to be analyzed and the reagent contained in thedry analysis element11 onto thedry analysis element11 through thelight measuring window31aand measures the optical density of thedry analysis element11. Thelight measuring head41 is mounted on the incubator body (not shown). As theincubator rotor30 is rotated by thedrive motor30, the distanced between the element chamber in the light measuring position and thelight measuring head41 periodically changes since the height of theincubator rotor30 in the light measuring position varies according to the angle at which theincubator rotor30 is mounted on therotating shaft36.
• As shown in FIG. 3, the optical density of the[0041]dry analysis element11 as measured by thelight measuring head41 is sent to anoperating section42 and is corrected by a correction means43 on the basis of a correction value which has been stored for the position of each element chamber33 (for the distance of eachelement chamber33 from thelight measuring head41 when theelement chamber33 is in the light measuring position). The correction means43 is provided with a correctingsection44. The correctingsection44 receives a signal from aposition detecting section45 which represents the position of theelement chamber33 which is stopped above the light measuring head41 (in the light measuring position) and reads out a correction value corresponding to theelement chamber33 stopped above thelight measuring head41 from a memory46. The operatingsection42 corrects the optical density of thedry analysis element11 in theelement chamber33 in the light measuring position on the basis of the correction value, thereby obtaining a true optical density of thedry analysis element11 free from influence of fluctuation in distance.
• The[0042]position detecting section45 detects the rotational phase of theincubator rotor30 by way of rotation of the motor38 (e.g., by the use of a rotary encoder) and detects theelement chamber33 which is stopped in the light measuring position. Though not shown, the control section of the biochemical analysis system1 which controls the overall operation of the system1 is provided with a bar code reader and bar codes representing information on the item to be analyzed of thedry analysis element11 to be inserted into eachelement chamber33 is read by the bar code reader. The information on the item to be analyzed of thedry analysis element11 to be inserted is stored together with theelement chamber33 in which thedry analysis element11 is inserted.
• The correction means[0043]43 is further provided with a calibratingsection47 inserts a calibration element whose optical density is known into each of theelement chambers33 of theincubator rotor30, receives the optical density of the calibration element as measured by thelight measuring head41 from the operatingsection42 and writes the correction value for the element chamber determined on the basis of the difference between the known optical density of the calibration element and the measured optical density of the same in the memory46.
• The[0044]operating section42 outputs corrected optical density to aconcentration calculating section48 and theconcentration calculating section48 determines the concentration of the component to be analyzed on the basis of the corrected optical density according to acalibration curve49 and outputs the concentration of the component thus determined as a measured concentration.
• Basic properties of the correction will be described with reference to FIGS. 4 and 5, hereinbelow. The sensitivity of the[0045]light measuring head41 changes with change in distance d to thedry analysis element11 generally as shown in FIG. 4. When a calibration element of a highly reflective ceramic whose optical density is known is measured, the output of thelight measuring head41 is maximized (Vo) at a pointD at which the distanced is optimal, and is reduced as the distance d is reduced or increased. For example, at pointa, where the distance d is smaller than at the point D, the output of thelight measuring head41 is reduced to V1 and at pointb, where the distance d is smaller than at the point D, the output of thelight measuring head41 is reduced to V2. This properties changes in proportion with change of the optical density of thedry analysis element11. On the basis of this fact, the correction value is set.
• FIG. 5 shows the relation between the output of the[0046]light measuring head41 before correction and the corrected optical density. In FIG. 5, Ko is a line of correlation between the measured optical density Vo (the output of the light measuring head41) as measured at the point D and the true optical density Eo. The correction value is set according to, for instance, correlation lines Ka and Kb (which are for the pointsa andb, respectively) which are obtained by moving parallel the line Ko so that the outputs V1 and V2 of thelight measuring head41 as measured at the points a and b correspond to the true optical density Eo.
• That is, an output Va of the[0047]light measuring head41 as measured at a distance from anelement chamber33 equal to that of the pointa is converted according to the correlation line Ka to an optical density Ea which is higher than uncorrected optical density Ea′ converted according to the correlation line Ko. Similarly, an output Vb of thelight measuring head41 as measured at a distance from anelement chamber33 equal to that of the pointb is converted according to the correlation line Kb to an optical density Eb which is higher than uncorrected optical density Eb′ converted according to the correlation line Ko.
• The distance by which the correlation line Ko is moved to obtain the correlation line Ka or Kb is a function of the distance d between the light measuring[0048]head41 and theelement chamber33 which can be represented by the rotating angle of theincubator rotor30. Accordingly, by measuring a calibration element whose optical density is known and determining the deviation of the measured optical density from the known optical density as a distance from the optimal distance where the sensitivity of thelight measuring head41 is maximized, the influence on the measured value of fluctuation of the distance between the light measuringhead41 and theelement chamber33 can be compensated for.
• For example,[0049]incubator rotors30 have different rotational displacement properties due to, for instance, processing accuracy and the distance to thelight measuring head41 differs from element chamber to element chamber (in the light measuring position). A calibration element whose optical density is known is inserted into each of theelement chambers33 and the optical density of the calibration element in eachelement chamber33 is measured while rotating theincubator rotor30 to bring theelement chambers33 to the light measuring position in sequence. The correction value is determined for eachelement chamber33 on the basis of the difference between the measured optical density and the known optical density, and the correction values for therespective element chambers33 are stored together with the angular positions of theincubator rotor30, i.e., the positions of therespective element chambers33. Then the output of thelight measuring head41 is corrected (the measured optical density is corrected) on the basis of the correction value specific to theelement chamber33.
• In FIG. 1, the[0050]sample tray2 comprises aturntable21 which is rotated in opposite directions. Fivesample cartridges7 are mounted on theturntable21 in an arcuate line. Thesample cartridges7 are removable separately from each other. Eachsample cartridge7 comprises asample holding portion71 which holds a sample container10 (a blood-collecting tube) holding therein a sample, and an analysiselement holding portion72 which holds a stack of virgindry analysis elements11 of different types.
• Consumables are held on the other part of the upper surface of the[0051]turntable21 along the outer periphery. For example, a number ofnozzle tips21, a mixing cup13 (a molded product provided with a plurality of cup-like recesses), adiluent container14 and acontainer15 for other purposes are held on theturntable21 along the outer periphery thereof. The consumables may be set on thesample tray2 in the form of cartridges like thesample cartridge7.
• The[0052]turntable21 of thesample tray2 is rotated in the regular direction or the reverse direction by a drive mechanism (not shown) to positions where the spottingnozzle unit5 operates. By controlling the angular position of the turntable and the position of the spottingnozzle unit5, predetermined operations required to spotting the sample on the analysis element such as mounting anozzle tip12, sucking a sample, diluent or the reference liquid, and mixing the sample and the diluent are carried out.
• An element transfer means (not shown) which transfers the[0053]dry analysis element11 is provided at the central portion of thesample tray2. The element transfer means comprises an element transfer member (an insertion lever) which is slid back and forth in a radial direction of thesample tray2 by a drive mechanism (not shown). The element transfer means causes the element transfer member to push adry analysis element11 out of asample cartridge7 into the spotting station, to push theelement11 spotted with the sample into theincubator3, and to further push theelement11 toward the center of theincubator3 after measurement to discard theelement11. The element transfer means controls the drive mechanism for theturntable21 to bring thesample cartridges7 to the spotting station in sequence. When plasma of the sample is to be filtered, aholder16 with a filter is mounted on thesample container10 set in thesample cartridge7 as shown in FIG. 1.
• The[0054]dry analysis element11 generally comprises a square mount and a reagent layer provided in the mount. A spotting hole is formed on the surface of the mount and the sample is spotted in the spotting hole. Thedry analysis element11 is provided with bar codes (not shown) representing information on the item to be analyzed.
• The spotting station (not shown) is for spotting a sample such as plasma, whole blood, serum, urine or the like on the[0055]dry analysis element11. Though not shown, a bar code reader for reading the bar code on theelement11 is provided on the upstream side of the spotting station. The bar code reader is for identifying the item of measurement and controlling the subsequent spotting and measurement, and for detecting the position of the element11 (whether theelement11 is upside down or in a wrong direction).
• The spotting[0056]nozzle unit5 comprises ahorizontal movement block51 which is movable in a horizontal direction and a pair of vertical movement blocks52 which are movable up and down on thehorizontal movement block51. A spottingnozzle53 is fixed on each of thevertical movement block52. Thehorizontal movement block51 and the vertical movement blocks52 are moved in the respective direction by drive means (not shown). The spottingnozzles53 are integrally moved right and left and are moved up and down independently of each other. For example, one of the spottingnozzles53 is for spotting the sample, and the other is for spotting the diluent.
• The spotting[0057]nozzle53 is in the form of a rod provided with an air passage extending in the axial direction and a pipette-like nozzle tip12 is fitted on the lower end portion thereof. The spottingnozzles53 are connected to air tubes respectively connected to syringe pumps (not shown), and a suction force and a discharge force are selectively supplied to the spottingnozzles53. After measurement, the usednozzle tips12 are removed from the spottingnozzles53 and discarded.
• The blood filtering unit[0058]6 is inserted into thesample container10 held in thesample tray2 and sucks plasma through theholder16 with a glass fiber filter which is mounted on the upper end of thesample container10, thereby separating plasma from the blood and holding the separated plasma in a cup formed on the top of theholder16. The blood filtering unit6 comprises a suckingmechanism61 which supplies suction force, and asuction pad62 which is connected to a suction pump (not shown) and attracts theholder16 under a suction force is provided on the lower end of the suckingmechanism61. The suckingmechanism61 is mounted on asupport post63 to be moved up and down by a drive mechanism (not shown). When the plasma is separated from the blood, the suckingmechanism61 is moved downward to be brought into a close contact with theholder16. In this state, the suction pump is operated to suck the whole blood in thesample container10, whereby the plasma separated from the blood is introduced into the cup formed on the top of theholder16. Thereafter, the suckingmechanism61 is returned to the initial position.
• In FIG. 1, a[0059]control panel18 is provided above theincubator3. Thesample tray2 and the spottingnozzle unit5 are covered with a transparentprotective lid19 which is openable.
• Operation of the biochemical analysis system[0060]1 will be described, hereinbelow. Asample container10 and one or more unsealeddry analysis elements11 suitable for the item of measurement are set in asample cartridge7 outside thesystem body17. Then thelid19 is opened and thesample cartridge7 is set in thesample tray2. When a plurality of samples are to be measured, a plurality ofsuitable sample cartridges7 are set in thesample tray2. Further consumables such as thenozzle tips12, the mixing cups13, thediluent containers14 and the like are set in thesample tray2.
• Then analysis is started. In case of emergency, analysis is interrupted and the[0061]sample cartridge7 to be analyzed urgently is set in a vacant space or in place of another sample cartridge.
• Blood plasma is first separated from the whole blood in the[0062]sample container10 by the blood filtering unit6. Then thesample tray2 is rotated to bring thesample cartridge7 containing therein a sample to be analyzed to the spotting station. Then one of thedry analysis elements11 in thesample cartridge7 is transferred to the spotting station by the element transfer member91 of the transfer means9. On the way to the spotting station, the bar code on theelement11 is read by the bar code reader and the item of analysis and the like are detected.
• When the item of analysis represented by the bar code is colorimetry, the[0063]sample tray2 is rotated to bring anozzle tip12 below the spottingnozzle53 and thenozzle tip12 is mounted on the spottingnozzle53. Then thesample container10 is moved and the spottingnozzle53 is moved downward to dip thenozzle tip12 into the sample and to cause thenozzle tip12 to suck the sample. Thereafter the spottingnozzle53 is moved to the spotting station and spots the sample onto thedry analysis element11 at the spotting station.
• Then the[0064]dry analysis element11 spotted with the sample is inserted into anelement chamber33 of theincubator3. In response to insertion of thedry analysis element11 into theelement chamber33, the pressingmember34 presses downward thedry analysis element11, whereby evaporation of the sample is prevented and thedry analysis element11 is heated to a predetermined temperature. After insertion of thedry analysis element11 into theelement chamber33, theincubator rotor30 is rotated to bring theelement chambers33 to the measuring position in sequence where thedry analysis element11 in thechamber33 is opposed to thelight measuring head41. After a predetermined time, change of the optical density of theelement11 due to reaction of the sample with the reagent is measured by thelight measuring head41. After the measurement, thedry analysis element11 is pushed toward the center by the element transfer member91 to be discarded. The result of the measurement is output and the usednozzle tip12 is removed from the spottingnozzle53. Then processing is ended.
• When the sample is to be diluted, e.g., when the blood is too thick to carry out accurate measurement, the[0065]sample tray2 is moved to bring thenozzle tip12 holding the sample to a mixingcup13. Then the spottingnozzle53 discharges the sample held by thenozzle tip12 into the mixingcup13. Then the usednozzle tip12 is removed from the spottingnozzle53, and anew nozzle tip12 is mounted on the spottingnozzle53. The spottingnozzle53 causes thenozzle tip12 to suck the diluent from thediluent container14 and to discharge the diluent into the mixingcup13. There after the spottingnozzle53 dips thenozzle tip12 into the mixing cup and causes thenozzle tip12 to repeat suck and discharge, thereby stirring the mixture in the mixingcup13. Then the spottingnozzle53 causes thenozzle tip12 to suck the diluted sample and moves thenozzle tip12 to the spotting station. At the spotting station, the spottingnozzle53 causes thenozzle tip12 to spot the diluted sample onto thedry analysis element11. Then the aforesaid, light measuring step, element discarding step and result outputting step follow.
• In the incubator of this embodiment, since the measured optical density output by the[0066]light measuring head41 is corrected according to the position of theelement chamber33, that is, the distance to thelight measuring head41 of theelement chamber33, fluctuation of the distance between the light measuringhead41 and theelement chamber33 due to errors and/or strain in processing and/or assembly can be compensated for, and accordingly, the optical density of thedry analysis element11 can be accurately measured without adding to the manufacturing cost of the incubator.
• FIG. 6 is a cross-sectional view showing an incubator in accordance with another embodiment of the present invention. The elements analogous to those shown in FIGS. 1 and 2 are given the same reference numerals and will not be described in detail here.[0067]
• The[0068]incubator103 of this embodiment comprises anincubator rotor30 and a measuring means4. Theincubator rotor30 comprises lower andupper disc members31 and32, and a plurality ofelement chambers33 in which thedry analysis elements11 are inserted are formed between the lower andupper disc members31 and32 arranged along the circumference of thedisc members31 and32 at regular intervals. The bottom surface of eachelement chamber33 is flush with the upper surface of the spotting station and thedry analysis element11 can be inserted into thechamber33 from the spotting station by simply pushing theelement11.
• Sliding[0069]holes32aare formed in theupper disc member32 to be opposed to theelement chambers33. A pressingmember34 is disposed above eachelement chamber33 with its upper portion slidably received in the slidinghole32a. The lower surface of the pressingmember34 presses downward thedry analysis element11 inserted into theelement chamber33 and tightly closes the spotting hole of the dry analysis element11 (through which the sample is spotted onto the element11) to prevent evaporation thereof. The outer edge of the lower portion of the pressingmember34 is tapered so that thedry analysis element11 inserted into theelement chamber33 is brought into abutment against the tapered surface to push upward the pressingmember34.
• A[0070]heater35 is provided in theupper disc member32 to heat thedry analysis elements11 in theelement chambers33. By controlling theheater36, the dry analysis elements can be held at a desired constant temperature (incubated).
• A[0071]light measuring window31ais formed in the bottom of thelower disc member31 opposed to each of theelement chambers33. Alight measuring head41 is positioned below thelight measuring window31aof theelement chamber33 stopped in a light measuring position shown in FIG. 2. A circular opening108awhich opens in the element discarding hole to be described later is formed in the central portion of thelower disc member31. Alower member136 is provided below the circular opening108a.
• The[0072]lower member136 is provided with a cone-like slant surface136awhich tapers downward toward the axis of rotation of theincubator rotor30, a cylindricalrotating shaft136bwhich is connected to the lower end of theslant surface136aand the inner space of which opens to the space defined by the cone-like slant surface136aso that the dry analysis element in each element chamber can be discarded outside theincubator3 through the space defined by the cone-like slant surface136aand the inner space of the cylindricalrotating shaft136b.
• A bearing[0073]member137 horizontally supports the cylindricalrotating shaft136bfor rotation about the axis of rotation of theincubator rotor30. When theslant surface136ais at an angle not smaller than 30° to the horizontal, thedry analysis element11 is surely slid on theslant surface136atoward the cylindricalrotating shaft136b.
• In the incubator of this arrangement, the[0074]rotating shaft136bneed not be large in diameter even if the number of thedry analysis elements11 to be accommodated in theincubator3 increases and the diameter of theincubator rotor30 increases, and accordingly, the bearingmember137 maybe small in diameter, where by theincubator3 can be manufactured at low cost. Further, since thedry analysis elements11 after measurement can be discarded by pushing thedry analysis elements11 only to theslant surface136a, the stroke of the element transfer member need not be enlarged even if the number of thedry analysis elements11 to be accommodated in theincubator3 increases and the diameter of theincubator rotor30 increases, whereby theincubator3 can be small in size and weight.
• Further by virtue of the[0075]lower member136 defining the cone-like slant surface136a, rigidity of theincubator rotor30 is increased and theincubator rotor30 can be rigid enough though it is small in weight, whereby wobbling of theincubator rotor30 can be suppressed without use of a sliding support and the measuring accuracy can be enhanced.

Claims (4)

What is claimed is:

1. An incubator comprising a rotating incubator rotor provided with a plurality of element chambers which are arranged along the outer periphery of the incubator rotor and each of which accommodates a dry analysis element spotted with a sample and incubates the dry analysis element and a light measuring means having a light measuring head which measures the optical density of the dry analysis element, wherein the improvement comprises that

the light measuring means is provided with a correction means which compensates for fluctuation in the value of the optical density of the dry analysis element in each of the element chambers as measured by the light measuring head generated due to fluctuation in the distance between the light measuring head and the element chamber on the basis of a correction value which has been stored in the correction means element chamber by element chamber.

2. An incubator as defined inclaim 1 in which the correction means sets the correction value for each element chamber by inserting a calibration element whose optical density is known into each of the element chambers of the incubator rotor, measuring the optical density of the calibration element with the light measuring head and determining the correction value for the element chamber on the basis of the difference between the known optical density of the calibration element and the measured optical density of the same.

3. An incubator comprising a rotating incubator rotor provided with a plurality of element chambers which are arranged along the outer periphery of the incubator rotor and each of which accommodates a dry analysis element spotted with a sample and incubates the dry analysis element, wherein the improvement comprises that

the incubator rotor is provided with a cone-like slant surface which is formed below the element chambers and tapers downward toward the axis of rotation of the incubator rotor, a cylindrical rotating shaft which is connected to the lower end of the slant surface and the inner space of which opens to the space defined by the cone-like slant surface so that the dry analysis element in each element chamber can be discarded outside the incubator through the space defined by the cone-like slant surface and the inner space of the cylindrical rotating shaft, and a bearing member which supports the cylindrical rotating shaft for rotation about the axis of rotation of the incubator rotor.

4. An incubator as defined inclaim 3 in which the slant surface is at an angle not smaller than 30° to the horizontal.

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