Automatic biochemical analyzer

There is disclosed a small-sized automatic biochemical analyzer requiring reduced amounts of reagents. An original sample is transferred to diluting containers on a diluting turntable. The diluted sample is transferred to reaction containers on a reaction turntable and analyzed. The original sample is once diluted. The aliquots of sample are taken from the diluted sample. Thus, a limitation imposed by the minimum volume of liquid that the instrument can meter out can be overcome. Let N be the total number of the diluting containers on the diluting turntable. The turntable is rotated in M pitches at a time. M and N do not have any common factor.

FIELD OF THE INVENTION 
The present invention relates to an automatic biochemical analyzer for 
collecting photometric data from plural reaction containers successively 
while rotating the containers into which aliquots of samples and reagents 
are pipetted and, more particularly, to an automatic biochemical analyzer 
having metering and diluting functions. 
BACKGROUND OF THE INVENTION 
Automatic chemical analyzers capable of analyzing a biochemical sample, 
such as blood or urine, in terms of plural items have been already 
proposed. For example, an automatic chemical analyzer described in 
Japanese Patent Laid-Open No. 2024/1993 comprises a sample disk holding a 
plurality of sample containers, a reaction disk holding a plurality of 
reaction containers, and a plurality of reagent disks holding a plurality 
of reagent containers. In this instrument, aliquots of sample in the 
sample containers set on the sample disk are drawn in by a pipetting 
mechanism and dispensed into the reaction containers on the reaction 
disks. Another pipetting mechanism draws in reagents from plural reagent 
disks and feeds the reagents into reaction containers. Thus, the sample is 
chemically analyzed in terms of various items in each reaction container. 
The sample and the reagent are held in their respective containers. 
Predetermined amounts of these sample and reagent are taken from the 
containers by pipettes and dispensed into the reaction containers. The 
volume of liquid that the instrument can meter out has a limitation. For 
example, the liquid mass around the tip of a pipette breaks at a location 
that is not fixed. Therefore, in the prior art technique, the minimum 
amount of liquid that can be metered with sufficient reproducibility is 
about 3 .mu.l. 
Generally, in a chemical analyzer, the amounts of a sample and a reagent 
put into a reaction container are set to a ratio of 100:1, taking account 
of the dynamic range of the induced chemical reaction. Since reagents are 
expensive, it is desired to minimize the amounts of reagents used. 
Accordingly, it may be considered to reduce the amount of sample subjected 
to a reaction. However, because of the limitation described above, it is 
impossible to reduce the amount of sample below about 3 .mu.l at present. 
SUMMARY OF THE INVENTION 
The present invention has been made to solve the foregoing problems. 
It is an object of the present invention to provide an automatic 
biochemical analyzer equipped with a sample-diluting mechanism to reduce 
the amount of sample required while still utilizing aliquots of sample at 
the minimum volume level that can be metered, whereby the amount of 
reagent used can be reduced. 
It is another object of the invention to provide an automatic biochemical 
analyzer permitting accurate dilution. 
It is a further object of the invention to provide an automatic chemical 
analyzer capable of accommodating itself to various items of analysis 
without the need to use larger diluting containers. 
It is a yet other object of the invention to provide an automatic 
biochemical analyzer that can be designed with increased degrees of 
freedom without the need to increase the size of the turntable of the 
diluting mechanism. 
It is a still other object of the invention to provide an automatic 
biochemical analyzer capable of analyzing a sample in terms of plural 
items only with a single diluting container. 
It is an additional object of the invention to provide an automatic 
biochemical analyzer capable of easily repeating analysis by the use of a 
diluting mechanism, irrespective of the original material used. 
It is a still further object of the invention to provide an automatic 
biochemical analyzer in which an analytical unit can achieve its potential 
even if a diluting system having throughput lower than that of the 
analytical unit is used. 
These objects are achieved in accordance with the teachings of the 
invention by an automatic biochemical analyzer comprising: a sample 
turntable having sample containers arranged thereon, the sample containers 
holding an original sample; a diluting turntable having diluting 
containers arranged thereon; a diluting pipette for drawing in the 
original sample from the sample containers and discharging the sample into 
the diluting containers together with a diluent; a reaction container 
turntable having reaction containers arranged thereon; and a sampling 
pipette for drawing in the diluted sample from the diluting containers and 
dispensing the diluted sample into the reaction containers. 
In the present invention, the sample is once diluted before reaction. 
Consequently, it is possible to overcome the limitation imposed on the 
minimum metered volume of sample as described above. In consequence, the 
amounts of reagents used can be reduced. 
In one feature of the invention, the diluting turntable is rotated in M 
pitches at a time. Let N be the total number of the diluting containers on 
the diluting turntable. M and N do not have any common factor. Therefore, 
the components of the diluting mechanism can be arranged with increased 
degrees of freedom. As a result, the instrument can be miniaturized. 
Other objects and features of the invention will appear in the course of 
the description thereof, which follows.

DETAILED DESCRIPTION OF THE INVENTION 
The whole structure of an automatic biochemical analyzer in accordance with 
the present invention is shown in FIG. 1. This analyzer is comprised of a 
sample turntable 1, a diluting turntable 2, a first reagent turntable 3, a 
second reagent turntable 4, and a reaction turntable 5 for holding plural 
reaction containers 51. A sample withdrawn from a living organism is held 
in plural sample containers 11, which in turn are set on the sample 
turntable 1. The diluting turntable 2 holds plural diluting containers. 
Each of the reagent turntables 3 and 4 holds plural reagent containers. A 
diluting pipette 12 for diluting the original sample and injecting it into 
the diluting containers on the diluting turntable is disposed between the 
sample turntable 1 and the diluting turntable 2. A sampling pipette 22 for 
transferring the diluted sample from the diluting containers to the 
reaction containers is mounted between the diluting turntable 2 and the 
reaction turntable 5. A reagent pipette 32 for pipetting a reagent into 
reaction containers is arranged between the first reagent turntable 3 and 
the reaction turntable 5. Similarly, another reagent pipette 42 for 
pipetting another reagent into reaction containers is located between the 
second reagent turntable 4 and the reaction turntable 5. 
The sample containers 11 are arranged circumferentially in two rows on the 
sample turntable 1. For example, each circumferential row is comprised of 
42 sample containers 11. In each row, the sample containers 11 are 
regularly spaced from each other by a substantially uniform pitch of 
360.degree./42. The turntable 1 is advanced incrementally, one pitch at a 
time. 
The diluting containers are arranged circumferentially in one row on the 
diluting turntable 2. For example, the number of the diluting containers 
is 120. These diluting containers are equally spaced from each other by a 
uniform pitch of 3.degree. (=360.degree./120). The diluting turntable 2 is 
advanced incrementally, for example, 47 pitches at a time. The reaction 
containers 51 are arranged circumferentially in one row on the reaction 
turntable 5. For instance, the number of the reaction containers 51 is 
221. 
When one of the sample containers 11 reaches an aspirating position of the 
sample turntable 1, the diluting pipette 12 draws in a given amount of the 
original sample from this sample container 11. The aspirated sample is 
discharged into the diluting container 21 in an injecting position of the 
diluting turntable 2, along with a diluent supplied from the diluting 
pipette itself. As a result, the original sample is mixed with the diluent 
inside the diluting container, thus producing a diluted sample. In an 
aspirating position of the sampling pipette 22, it aspirates a given 
amount of the diluted sample. In an injecting position of the reaction 
turntable 5, the aspirated diluted sample is injected into the reaction 
container 51. 
A stirring device 23 and a washing device 24 are disposed around the 
diluting turntable 2, as well as the diluting pipette 12 and the sampling 
pipette 22, to stir the diluted sample and to wash the diluting 
containers. To permit these devices to be arranged with sufficient degrees 
of freedom, the diluting turntable 21 is advanced incrementally in a 
manner described later. 
The reagent pipettes 32 and 42 take in first and second reagents, 
respectively, from reagent containers 31 and 41, respectively, and inject 
them, at injecting positions, into the reaction containers 51 in which the 
diluted sample has been already introduced. The absorbance of each aliquot 
of diluted sample mixed with either reagent is kept detected for a given 
time at a detection position D by a detector 52. The reaction container 51 
undergone the detection is washed by the washing device 53 in a washing 
position W. The various operations, such as the operation of the 
turntables, the operation of the pipettes, the operation of the stirring 
device, the operation of the washing device, and the operation of the 
detector, are under control of a control unit consisting, for example, of 
a computer (not shown). 
In the present invention, the original sample is reacted after diluted in 
this way. The necessity of the dilution is next described. As described 
previously, the minimum volume of liquid that the instrument can meter out 
has a limitation. Where a given amount of liquid is delivered from a 
pipette, the minimum amount of liquid that can be metered with sufficient 
reproducibility is about 3 .mu.l, taking account of the fact that when the 
discharge ends, the liquid mass breaks in a nonreproducible manner around 
the tip of the pipette. 
In a biochemical analyzer, 300 .mu.l of reagent and 3 .mu.l of sample 
(=100:1) are introduced into each reaction container. This ratio of 100:1 
is determined, taking account of the saturation of the detected absorbance 
and the magnitude of the detected signal. In particular, if the ratio of 
the sample is too great, the detected absorbance saturates, thus narrowing 
the dynamic range. If the ratio of the sample is too small, the detected 
signal is too small, thereby deteriorating the detection accuracy. Taking 
account of these factors, the above-described ratio is set so that the 
variations in the absorbance effectively lie within the dynamic range of 
the detector. 
On the other hand, reagents are expensive and so it is desired to minimize 
the amounts of reagents used. Accordingly, if the operator wants to 
decrease the reagent introduced into each reaction container down to 100 
.mu.l, the volume of the sample is required to be set to 1 .mu.l because 
of the relation with the dynamic range of the detector. However, this 
amount 1 .mu.l is below the minimum metered amount. Hence, it is 
impossible to meter reproducibly and accurately. 
If the sample is diluted five times, it follows that 5 .mu.l of diluted 
sample contains 1 .mu.l of the original sample. Therefore, even if the 
volume of the reagent is reduced down to 100 .mu.l, the dynamic range of 
the detector cannot be exceeded. For example, if the operator causes the 
diluting pipette 12 to draw in 20 .mu.l of the original sample, dilute it 
with 80 .mu.l of a diluent, transfer the diluted sample into the diluting 
container 21 so that the sample is diluted five times, and causes the 
sampling pipette to draw in 5 .mu.l of the diluted sample, then the drawn 
sample contains 1 .mu.l of the sample. 
The present invention provides the diluting turntable 2, based on the 
concept described above. On this diluting turntable, the original sample 
is diluted 4 to 10 times. This produces increased amounts of diluted 
sample. Relatively large metered amounts of diluted sample are put into 
the reaction containers. Consequently, the amounts of reagents used can be 
reduced. At the same time, aliquots of sample can be metered accurately. 
FIGS. 2(a) and 2(b) show a diluting mechanism used in the biochemical 
analyzer described above. The diluting pipette 12 is rotated between the 
sample turntable 1 and the diluting turntable 2 and from either turntable 
into a washing bottle 17 by a diluting pipette drive mechanism 18. This 
drive mechanism 18 is also equipped with a mechanism to move the pipette 
12 up and down so that the height of the pipette 12 is adjusted to any 
approaching one of the turntables 1, 2 and the washing bottle 17. 
It is assumed that the original sample is diluted five times. First, a 
diluent pump 16 draws in 150 .mu.l of diluent (normally water) via a valve 
14 and holds the drawn diluent. Under this condition, the diluting pipette 
12 is filled with the diluent up to its tip. Then, the diluting pipette 12 
is inserted into the sample container 11. A sample-aspirating pump 15 is 
operated to draw 30 .mu.l, for example, of sample into the front end 
portion of the diluting pipette 12. Subsequently, the diluting pipette 12 
is moved to the diluting container 21, and the diluting pump 16 is 
operated to discharge the 150 .mu.l of diluent previously aspirated from 
the pump. As a result, 30 .mu.l of sample and 120 .mu.l of diluent are 
discharged into the diluting container 21. In consequence, a diluted 
sample is prepared inside the diluting container by diluting the original 
sample five times. 
On finishing the diluting operation, the diluting pipette 12 is moved into 
the washing bottle 17, where the pipette is washed. The inside of the 
diluting pipette 12 is washed with a high-pressure cleaning liquid sent 
from a high-pressure washing pump HWP via the valve 14. The outside is 
washed with a cleaning liquid sent from a low-pressure washing pump LWP. 
The cleaning liquid sent from the high-pressure washing pump HWP is water 
deaerated so that no bubbles are left in the pipette; otherwise the 
metering operation would produce errors. This cleaning liquid is also used 
as a diluent. 
To enhance the washing effect, a high pressure is applied to the cleaning 
liquid from the high-pressure washing pump HWP. As a result, the cleaning 
liquid is swiftly swept through the diluting pipette to wash away the 
remaining sample almost fully. Since the low-pressure washing pump LWP 
acts to wash the outside of the pipette, the pump LWP delivers a 
low-pressure cleaning liquid. The used cleaning liquids are drained into a 
waste tank. 
The sampling pipette 22 is rotated between the diluting turntable 2 and the 
reaction turntable 5 and from either turntable into a washing bottle 28 by 
a sampling pipette drive mechanism 29.This drive mechanism 29 is also 
equipped with a mechanism to move the pipette 22 up and down so that the 
height of the pipette 22 is adjusted to any approaching one of the 
turntables 2, 5 and the washing bottle 28. 
When the sampling pipette drive mechanism 29 moves the sampling pipette 22 
to one diluting container on the diluting turntable 2, a sampling pump 27 
is operated to draw 5 .mu.l, for example, of diluted sample into the 
pipette. When the pipette 22 subsequently arrives at one reaction 
container 51 on the reaction turntable, the sampling pump 27 is operated 
to discharge the 5 .mu.l of drawn diluted sample into the reaction 
container. The result is that the diluted sample containing 1 .mu.l of the 
original sample is injected into the reaction container. The used sampling 
pipette 22 is washed in the washing bottle 28. In the same way as in the 
case of the diluting pipette, the inside of the sampling pipette 22 is 
washed with the cleaning liquid sent from the high-pressure washing pump 
HWP. The outside is washed with the low-pressure cleaning liquid sent from 
the low-pressure washing pump LWP. The used cleaning liquids are drained 
off into the waste tank. 
FIG. 2(b) illustrates washing, dilution, and stirring performed on the 
diluting turntable. Let N be the total number of the diluting containers 
arranged circumferentially on the diluting turntable. These diluting 
containers are spaced from each other by a uniform pitch. The diluting 
turntable 1 is rotated incrementally in one direction, M pitches at a 
time. M and N do not have any common factor. 
For example, 120 diluting containers are set on the diluting turntable. 
This turntable is rotated through an angle corresponding to 47 diluting 
containers at a time. After coming to a halt for a short time, the 
turntable 1 is rotated in the same direction through the same angle 
corresponding to the next 47 diluting containers. Subsequently, these 
incremental movement and halt are repeated. Suppose that 120 angular 
positions are assigned to the circumference of the diluting turntable 
according to the arrangement of the diluting containers. If a diluted 
original sample is injected into the diluting container in position 1, 
this container arrives at position 48 and halts there after the next 
incremental movement. Subsequently, this container arrives at positions 1, 
48, 95, . . . , 79, . . . , 74, and 1 sequentially. 
At position 48, stirring is done. At position 95, the sampling pipette 22 
takes in a required amount of the stirred, diluted sample. At position 79, 
the remaining diluted sample is drained off and washing is done. At 
position 74, the washed diluting container is dried. 
The stirring device 23 has a stirring rod 23c reciprocated between the 
diluting container 21 and a washing bottle 23b. At position 48, the 
stirring rod 23c stirs the diluted sample in the diluting container. In 
the washing bottle 23b, the stirring rod 23c is washed with the cleaning 
liquid sent from the low-pressure washing pump LWP via a solenoid valve 
23a. 
The wash/dry mechanism 24 washes the diluting container at position 79 and, 
at the same time, dries the washed diluted container at position 74. In 
particular, at position 79, the remaining diluted sample is drawn in via a 
solenoid valve 24c. Then, a washing pump 24a injects a given amount of 
cleaning liquid into the diluting container. At this time, the cleaning 
liquid is aspirated from the top of the diluting container under a 
negative pressure via a solenoid valve 24b to prevent the cleaning liquid 
from flowing over the diluting container. The injected cleaning liquid is 
aspirated under a negative pressure via the solenoid valve 24c that is 
again opened. Subsequently, injection of the cleaning liquid and 
aspiration are repeated twice, for example, thus finishing the washing 
operation. At position 74, the cleaning liquid adhering to the inner wall 
of the diluting container is attracted via a solenoid valve 24d, and the 
diluting container is dried. 
The original sample is analyzed in terms of specified items. The number of 
the specified items is determined independently for each different sample. 
Of course, as the number of items specified for one sample is increased, 
the amount of diluted sample required for analysis increases. 
Consequently, more diluted sample must be prepared. 
Suppose that the sample is diluted five times. In one case, the amount of 
diluted sample required for analysis is 150 .mu.l. In the other case, the 
amount is 600 .mu.l. These two cases are now discussed. It is assumed that 
150 .mu.l of diluted sample and 600 .mu.l of diluted sample should be 
prepared in one diluting operation. For the 150 .mu.l of diluted sample, 
it is necessary to send 30 .mu.l of original sample and 120 .mu.l of 
diluent from the diluting pipette into the diluting container. For the 600 
.mu.l, it is necessary to transfer 120 .mu.l of original sample and 480 
.mu.l of diluent from the diluting pipette into the diluting container. 
If the amount of aspirated original sample and the amount of the diluent 
introduced into the diluting container in one operation vary in this way, 
the proportionality of the amount of the discharged liquid to the amount 
of the aspirated liquid does not hold. As a result, the factor by which 
the sample is diluted changes. More specifically, the inside of the 
pipette that aspirates and discharges liquid is wetted with liquid and 
thus the liquid remains on the inner wall surface. For this reason, the 
movement of the pump that draws in and discharges liquid is not completely 
coincident with the amount of liquid aspirated or discharged. Furthermore, 
the drive mechanism of this pump inevitably involves a play and so the 
proportionality associated with the amount of movement of the pump is not 
always high. Therefore, the above-described two cases frequently are not 
equal in dilution factor. In the former case, 30 .mu.l of sample and 120 
.mu.l of diluent are drawn in, and 480 .mu.l of liquid is discharged to 
accomplish a dilution factor of 5. In the latter case, 120 .mu.l of sample 
is aspirated and 480 .mu.l of diluent is discharged, so that a total 
amount of 600 .mu.l is obtained. 
Accordingly, in the present invention, the amount of sample drawn into the 
diluting pipette and the amount of diluent delivered from the pipette in 
one diluting operation are made equal. That is, a constant amount of 
diluted sample is prepared in one diluting operation. If more diluted 
sample is necessary, the same diluting operation is repeated. In this way, 
an amount of diluted sample required for analysis is obtained. 
For example, it is assumed that the amount of original sample drawn in and 
the amount of diluent discharged are maintained at 30 .mu.l and 120 .mu.l, 
respectively. That is, 150 .mu.l of diluted sample is prepared in one 
diluting operation. Suppose that the amounts of diluted sample necessary 
for analysis are 300 .mu.l, 450 .mu.l, and 600 .mu.l, respectively. In 
this case, 2, 3, and 4 diluting operations are performed, respectively. If 
these amounts of diluted sample are created in a diluting container that 
can hold up to 300 .mu.l, then the associated factors are given in the 
following Table 1. 
TABLE 1 
______________________________________ 
amount of amount of number of used 
number of 
original amount of 
diluted diluting diluting 
sample diluent sample containers 
operations 
______________________________________ 
1 30 .mu.l 120 .mu.l 
150 .mu.l 
1 1 
2 30 .mu.l .times. 2 
120 .mu.l .times. 2 
300 .mu.l 
1 2 
3 30 .mu.l .times. 3 
120 .mu.l .times. 3 
450 .mu.l 
2 3 
4 30 .mu.l .times. 4 
120 .mu.l .times. 4 
600 .mu.l 
2 4 
______________________________________ 
The dilution factor of the sample can be maintained constant by regulating 
the amount of aspirated sample and the amount of discharged diluent in 
this way. Also, an amount of diluted sample necessary for analysis can be 
obtained by repeating the suction and delivery of given amounts. 
In one conceivable method, one diluting container is disposed for each one 
sample. Diluted sample necessary for analysis may be all held in the 
single container. Where all items of analysis are specified, a maximum 
amount of diluted sample is necessary. At this time, the diluting 
container must large enough to hold the maximum amount of diluted sample. 
Such a large diluting container has a large dead volume that is left 
behind and cannot be aspirated. This increases the amounts of wasted 
sample and diluent. Also, the number of diluted containers placed on the 
diluting turntable decreases. If the number is increased, the diluting 
turntable is increased in size and thus the whole instrument is made 
larger. 
Accordingly, in the present invention, diluting containers each having a 
small capacity are used. Where a large amount of diluted sample is 
necessary, plural diluting containers are used for one sample. For 
example, as shown in Table 1 above, each diluting container has a capacity 
of 300 .mu.l. The diluted sample can be divided into aliquots up to 300 
.mu.l. Where the amount of the required diluted sample is 150 .mu.l or 300 
.mu.l, one diluting container is employed. Where the volume of the 
required diluted sample is 450 .mu.l or 600 .mu.l, two diluting containers 
are used. Where the amount of the necessitated diluted sample is in excess 
of 300 .mu.l, the number of diluting containers used is increased 
accordingly. 
As a result, the dead volume of the container can be reduced. More diluting 
containers can be arranged on a small-sized diluting turntable. Hence, the 
instrument can be miniaturized. 
The diluting containers are conveyed by the diluting turntable in a manner 
described below. Let N be the total number of the diluting containers 
arranged circumferentially on the diluting turntable. These diluting 
containers are spaced from each other by a uniform pitch. The diluting 
turntable is rotated in M pitches at a time. Notice that M and N do not 
have any common factor, excluding 1. Thus, all the diluting containers can 
be successively used. Furthermore, the pipette and the cleaning mechanism 
can be set at positions that are better than where the containers are 
rotated in one pitch at a time, from a viewpoint of design of the 
instrument. 
Assuming that N=15 and M=4, the principle of conveyance of the diluting 
containers in accordance with the invention is next described by referring 
to FIGS. 3(a) and 3(b). In FIG. 3(a), 15 diluting containers a-o are 
circumferentially uniformly spaced from each other on the diluting 
turntable with a given pitch. The turntable is rotated in a clockwise 
direction incrementally, 4 pitches at a time. Whenever the turntable 
halts, the sample and the diluent are discharged in the discharging 
position of the diluting pipette. In the 3 other positions, stirring, 
aspiration by the sampling pipette, and washing are respectively done. In 
FIG. 3(a), the discharging position of the diluting pipette is indicated 
by numeral 1. The diluting containers come to a halt at positions 1-15. 
Under the condition shown in FIG. 3(a), the diluting turntable 2 is rotated 
in a clockwise direction indicated by the arrow, 4 pitches (M=4) at a 
time. The diluting containers a, e, i, m, b, f, j, n, c, g, k, o, d, h, 
and l are successively brought into the discharging position of the 
diluting pipette. That is, when the turntable is rotated in 15 steps, 
every diluting container is once brought into the discharging position 1 
of the diluting pipette. 
FIG. 3(b) shows movement of the diluting container a as the turntable is 
rotated in steps from the position shown in FIG. 3(a). At the first halt 
time, the container a comes to a halt at position 1. At the second halt 
time, it comes to a halt at position 5. At the third halt time, it comes 
to a halt at position 9. The same principle applies to the other 14 
diluting containers. 
In this way, the diluting containers coming to a halt at the discharging 
position of the diluting pipette are rotated in steps. Whenever each 
container is rotated in one step, the container is rotated in 4 pitches. 
Therefore, the following arrangement can be adopted. As shown in FIG. 
3(c), a stirring mechanism is disposed at position 5 to perform a stirring 
operation. The sampling pipette is located at position 9 to effect a 
sampling operation. A washing mechanism is placed at position 14 to 
perform a washing operation. A drying mechanism is installed at position 
11 to effect a drying operation. In this arrangement, the various 
mechanisms are not very close to each other and, therefore, any 
countermeasure for preventing the mechanisms from interfering from each 
other can be omitted. 
As shown in FIG. 3(d), it is also possible to place the stirring mechanism, 
the sampling pipette, the washing mechanism, and the drying mechanism at 
positions 13, 6, 14, and 11, respectively. 
In this way, where the novel method of conveying the diluting containers is 
used, the various mechanisms (i.e., the diluting pipette, the stirring 
mechanism, the sampling pipette, the washing mechanism, and the drying 
mechanism) can be placed with increased degrees of freedom. The 
construction of the instrument can be easily optimized. 
In the example shown in FIGS. 3(a)-3(d), the number of the containers is 
set to 15 for simplicity of illustration. The containers can be arranged 
with greater degrees of freedom by increasing the number. We now give an 
example. The number of installed diluting containers is 120. The turntable 
is rotated in 47 pitches at a time. At position 1, the diluting pipette 
(DPP) injects an original sample and a diluent. The stirring device is 
represented by MIX. The sampling pipette is represented by SPP. The 
washing device is represented by W. The drying mechanism is represented by 
C. The following sequence can be adopted: 
1 (DDP), 48(MIX), 95(SPP), 22, 69, 116, 43, 90, 17, 64, 111, 38, 85, 12, 
59, 106, 33, 80, 7, 54, 101, 28, 75, 2, 49, 96, 23, 70, 117, 44, 91, 18, 
65, 112, 39, 86, 13, 60, 107, 34, 81, 8, 55, 102, 29, 76, 3, 50, 97, 24, 
71, 118, 45, 92, 19, 66, 113, 40, 87, 14, 61, 108, 35, 82, 9, 56, 103, 30, 
77, 4, 51, 98, 25, 72, 119, 46, 93, 20, 67, 114, 41, 88, 15, 62, 109, 36, 
83, 10, 57, 104, 31, 78, 5, 52, 99, 26, 73, 120, 47, 94, 21, 68, 115, 42, 
89, 16, 63, 110, 37, 84, 11, 58, 105, 32, 79(W), 6, 53, 100, 27, 74(C), 
and 
1. This sequence is described in detail below. 
(1) At position 1, the diluting pipette (DPP) injects the original sample 
and the diluent into some diluting container. 
(2) The diluting turntable is rotated in 47 pitches in one step and comes 
to a halt. As a result, the above-described diluting container is moved 
into position 48. 
(3) At position 48, the stirring device (MIX) stirs the sample and diluent. 
(4) The diluting turntable is rotated further in 47 pitches in one step and 
comes to a halt. The container arrives at position 95. 
(5) At position 95, the sampling pipette (SPP) draws in a required amount 
of the diluted sample from the diluting container. 
(6) The turntable is further rotated in 112 steps, so that the diluting 
container reaches position 79. 
(7) At position 79, the diluting container is washed by the washing 
mechanism W. 
(8) The turntable is further rotated in 5 steps. The container arrives at 
position 74. 
(9) At position 74, the cleaning liquid is cleared from the diluting 
container by the drying mechanism C and thus the container is dried. 
These operations are performed where a diluted sample in one diluting 
container is analyzed in terms of one item. It may be sometimes necessary 
to analyze a diluted sample in one diluting container in terms of plural 
items. Plural different reagents corresponding to the items of analysis 
are placed on the reagent turntable. In this embodiment, the sample can be 
analyzed, for example, in terms of up to 40 items. Where one diluted 
sample is analyzed in terms of plural items, the following operation is 
carried out. 
For illustration, containers holding a diluted sample are used 
successively, and numbers such as No. 1, No. 2, etc. are given to them. 
(1) When the No. 1 diluting container arrives at position 1, the diluting 
pipette (DPP) injects a first original sample and a diluent. 
(2) The diluting turntable is rotated in 47 pitches in 1 step. The No. 1 
container is moved into position 48. 
(3) At position 48, the stirring device (MIX) stirs the liquids in the No. 
1 container. At the same time, the diluting pipette introduces a second 
original sample and a diluent into the No. 2 diluting container. 
(4) The diluting turntable is further rotated in 47 pitches in 1 step. The 
No. 1 container reaches position 95. 
(5) At position 95, the diluting pipette takes in a diluted sample from the 
No. 1 container for the first item of analysis. At this time, the diluted 
sample of the second original sample in the No. 2 container is stirred at 
position 48. A third original sample and a diluent are injected into the 
No. 3 diluting container at position 1. 
(6) At position 95, the sampling pipette (SPP) takes in a diluted sample 
from the No. 1 container for the second item of analysis. From now on, the 
sampling of the diluted sample is repeated necessary times at position 95. 
During this process, the diluting turntable is not rotated, and no 
operations are performed on the other containers. 
(7) The diluting turntable is rotated in 47 pitches in 1 step to move the 
No. 1 container into position 22, the No. 2 container into position 95, 
the No. 3 container into position 48, and the No. 4 container into 
position 1. The liquids in the No. 3 containers are stirred. The diluting 
pipette (DPP) injects a fourth original sample and a diluent into the No. 
4 diluting container. 
(8) If plural items of analysis are specified for the diluted sample of the 
second original sample in the No. 2 diluting container, the sampling 
pipette repeats sampling necessary times at position 95. During this 
process, the diluting sample does not turn, and no operations are 
performed on the other containers. 
(9) After this, these operations are repeated. Every diluting container 
reaching position 79 is washed. Every diluting container arriving at 
position 74 is dried. 
In the analytical process described above, it may be necessary to reexamine 
samples providing data indicating an abnormality. With the prior art 
automatic biochemical analyzer, the reexamination has been urged to use 
the original sample. Usually, the original sample is held in a large-sized 
blood-gathering tube. An instrument having high throughput (i.e., capable 
of performing a large amount of processing per unit time) needs a large 
space to keep in stock the already analyzed original sample for a long 
time in preparation for reexamination. Also, a complex structure is 
necessary to return the stocked original sample to the position for 
reexamination. 
In contrast, in the present invention, the diluted sample is held on the 
diluting turntable without being washed away after the diluted sample is 
aspirated at position 95 until the turntable is rotated in 112 steps. 
Where reexamination of any diluting container undergone analysis and 
already providing analytical data is required, the diluting turntable is 
temporarily rotated so as to bring the diluting container into position 
95. At this position 95, the sampling pipette (SPP) again takes in a 
diluted sample. 
For instance, if it is necessary to reexamine the diluted sample in the 
diluting container arriving at position 87, the diluting turntable is 
rotated so that this container moves from position 87 to position 95. When 
the sampling by the sampling pipette ends, the diluting turntable is 
rotated to shift the diluting container from position 87 to the next 
position 14. Subsequently, the turntable is rotated in steps in a normal 
manner. Where reexamination is not required, the aforementioned operations 
will be repeated. 
In this way, the diluting turntable is rotated in M pitches at a time. Let 
N be the total number of the diluting containers on the diluting 
turntable. M and N do not have any common factor, excluding 1. This 
increases the number of degrees of freedom in arranging the pipetting 
portion relying on the diluting pipette, the stirring portion, and the 
sampling portion. Consequently, the instrument can be designed ideally. 
Furthermore, the components can be so arranged that as the turntable is 
rotated in steps, the pipetting relying on the diluting pipette, the 
stirring, and the sampling are successively carried out. Consequently, 
immediately after aspiration of a sample, it can be analyzed. 
Also, diluting containers permitting automatic reexamination and 
corresponding to 112 stepwise movements as described above can be secured 
on the diluting turntable. Therefore, automatic reexamination can be 
carried out with a small space and a simple mechanism. 
In addition, the diluted sample prepared in one diluting container can be 
analyzed in terms of plural items and so the amount of wasted sample can 
be reduced to a minimum. Also, the accuracy at which the sample is diluted 
can be improved compared with the case in which the sample is diluted for 
each individual item. 
Moreover, the diluting turntable is not rotated while plural aliquots of 
sample are being taken from the diluted sample for plural items of 
analysis. During this processing, aspiration of the original sample, 
stirring, washing of the diluting container, and so on can be performed. 
Therefore, the throughput of the sample-diluting system can be set lower 
than that of the analysis instrument. 
Normally, the original sample is metered in conformity with the capability 
of the analytical unit to process samples. However, the original sample is 
put in a large blood-collecting tube and manually processed. Therefore, 
the maximum rate at which the original sample is metered has a limitation. 
On the other hand, the analytical unit that are only required to inject 
aliquots of sample into small reaction containers is relatively easy to 
provide greater throughput. However, if the throughput of the analytical 
unit is increased, the metering of the sample cannot follow. In 
consequence, it is difficult to achieve its maximum capability. 
Accordingly, in the present invention, the operating speed of the diluting 
pipette is made lower than that of the sampling pipette. While the 
sampling pipette is aspirating the sample, the diluted sample is 
aspirated, discharged, stirred, and stocked. Consequently, a great drop in 
the throughput of the analytical portion is prevented. 
This is described in further detail by giving an example in which the 
diluting system can process one sample in three seconds and the analytical 
portion can take in one aliquot of diluted sample in 1.5 seconds. 
It is first assumed that the sample in the single diluting container 
described above is analyzed in terms of plural items. 
(1) At position 95, the sampling pipette aspirates a diluted sample from 
the No. 1 diluting container for a cycle time of 1.5 seconds for the first 
item of analysis. 
(2) At position 95, the sampling pipette aspirates a diluted sample from 
the No. 1 diluting container for a cycle time of 1.5 seconds for the 
second item of analysis. 
(3) During the cycles (1) and (2) above, or for 3 seconds, the next diluted 
sample in the No. 2 container is stirred at position 48. 
(4) During the cycles (1) and (2) above, or for 3 seconds, a third original 
sample is injected into the No. 3 diluting container, together with a 
diluent, at position 1. 
(5) At position 95, the sampling pipette aspirates a diluted sample from 
the No. 1 diluting container for a cycle time of 1.5 seconds for the third 
item of analysis. 
During these process steps, the turntable does not turn, and no operations 
are performed on the other containers. Subsequently, the above-described 
process is repeated until aliquots of diluted sample for all specified 
items of analysis are taken. The same process is repeated when the 
diluted, second original sample arrives at position 95. 
In this manner, normally, the diluted sample in one diluting container is 
analyzed in terms of plural items. During this analysis, pipetting and 
stirring of the subsequent samples are done. Therefore, if a diluting 
system having a low processing rate is adopted, it is unlikely that the 
throughput of the analytical unit of higher processing rate is 
deteriorated greatly. 
The diluted sample in the No. 1 diluting container may be required to be 
analyzed in terms of one item, which is an exceptional example and 
described next. 
(1) At position 95, the sampling pipette aspirates a diluted sample from 
the No. 1 diluting container for a cycle time of 1.5 seconds for the first 
item of analysis. 
(2) Since the second item of analysis is not specified, no work is done for 
the next cycle of 1.5 seconds. 
(3) During the cycles (1) and (2) above, or for 3 seconds, the diluted 
second sample in the No. 2 container is stirred at position 48. 
(4) During the cycles (1) and (2) above, a third original sample is 
injected into the No. 3 diluting container, together with a diluent, at 
position 1. 
(5) The diluting turntable is rotated in 47 pitches in one step to move the 
No. 2 diluting container into position 95. 
(6) At position 95, the sampling pipette aspirates a diluted sample from 
the No. 2 diluting container for a cycle time of 1.5 seconds for the first 
item of analysis. 
(7) At position 95, the sampling pipette aspirates a diluted sample from 
the No. 2 diluting container for a cycle time of 1.5 seconds for the 
second item of analysis. 
(8) During the cycles (6) and (7) above, or for 3 seconds, the diluted 
second sample in the No. 3 diluting container is stirred. 
(9) During the cycles (6) and (7) above, the next sample is injected into 
the No. 4 diluting container, together with a diluent, for a cycle time of 
3 seconds. 
(10) At position 95, the sampling pipette aspirates a diluted sample from 
the No. 2 diluting container for the third item of analysis. 
These operations are subsequently repeated until aliquots of the diluted 
sample for all the items of analysis are taken. The same processing is 
repeated when the next original sample diluted arrives at position 95. 
Reagent pipettes are now described. The prior art analysis instrument has 
used reagent pipettes of the same diameter. The reagent pipettes are 
washed before aspiration of sample. Inevitably, the cleaning liquid is 
left at the tip of each pipette. This remaining cleaning liquid 
deteriorates the accuracy at which the aspirated sample is metered. 
Also, when a reagent is discharged, it inevitably adheres to the tip of the 
pipette and remains there. The amount of discharged reagent decreases by 
an amount equal to the amount of the remaining liquid. To prevent the 
accuracies of the amounts of reagent aspirated and discharged from 
deteriorating, it is necessary to minimize the diameter of the reagent 
pipette at its tip. However, as the throughput of the today's automatic 
biochemical analyzer improves, the time available to aspirate and 
discharge a reagent is shortened. If the tip is thinned, the viscous 
resistance of the reagent makes brief aspiration infeasible. 
Normally, therefore, the first and second reagents differ in the amount of 
usage. For example, the amount of the first reagent is 2 to 4 times as 
much as the amount of the second reagent. Accordingly, in the present 
invention, the diameter at the tip of the pipette for the first reagent is 
made different from the diameter at the tip of the pipette for the second 
reagent. For example, the diameter of the pipette for the first reagent is 
made 1.5 to 3 times as large as the diameter of the pipette for the second 
reagent, since the first reagent is aspirated more. 
For example, where the first reagent for aspirating and discharging 50 to 
150 .mu.l and the second reagent pipette for aspirating and discharging 20 
to 60 .mu.l are used as shown in FIG. 4, the first reagent pipette has a 
diameter of 0.4-0.8 mm, while the second reagent pipette has a diameter of 
0.2-0.4 mm. The accuracy of the amount of liquid pipetted can be maximized 
according to the amount of treated reagent by selecting the inside 
diameters of the pipettes for the first and second reagents according to 
the amounts of treated reagents. 
As described thus far, the present invention yields the following 
advantages. Since a diluting turntable used for dilution is provided, the 
amount of used original sample can be reduced. Also, the amount of reagent 
used can be diminished. An automatic analyzer can be built, using a small 
diluting turntable. Furthermore, the instrument can be designed with 
sufficient degrees of freedom. Each sample can be analyzed in terms of 
plural items with one diluting container. Automatic reexamination can be 
easily done, using a diluting mechanism. Even if a diluting system having 
throughput lower than that of the analytical unit is used, the analytical 
unit can display its ability to the full. 
FIG. 4(a) illustrates a second reagent pipette having a capacity of 20 to 
60 .mu.l and FIG. 4(b) illustrates a first reagent pipette having a 
capacity of 50 to 150 .mu.l. 
Having thus described our invention with the detail and particularity 
required by the Patent Laws, what is desired protected by Letters Patent 
is set forth in the following claims.