Conveying system for analytical samples

A processing station is provided for removing a cuvette 1 from a transport magazine 2, for transferring the cuvette to a position for processing in order to carry out a processing step such as adding samples, adding reagents or mixing, and for returning the cuvette to the transport magazine after processing.

BACKGROUND OF THE INVENTION 
The invention relates to a station for processing analytical samples in 
cuvettes in a device for chemical and biochemical analysis comprising a 
conveyor for conveying cuvettes to individual processing stations. 
Automatic analytical devices usually operate on the following principle: 
samples for analysis or parts thereof are placed in cuvettes and then 
subjected to a number of processing steps such as addition (pipetting) of 
reagents, mixing, incubation etc., and the reactions are measured 
repeatedly during processing and/or once at the end of processing. The 
operating sequence is usually as follows: the cuvettes containing the 
samples for analysis are disposed in a fixed sequence on a conveying means 
and travel through various processing stations, or alternatively in 
"batch" processing, as conventional in the case of "centrifugal" analysers 
devices, all the cuvettes are disposed on a carrier (rotor) and are 
subjected substantially simultaneously to be the processing steps and 
measurements. Analytical systems operating on these principles give good 
service in large clinics and analytical centres where large numbers of 
samples have to processed. 
In view, however, of the present variety of possible forms of analysis and 
the medical requirements, particularly in clinical chemistry, it has been 
found that the automatic analytical devices hitherto used conventionally 
for throughput of large quantities of samples are not sufficiently 
flexible for providing analytical profiles (full random access) 
specifically adapted to individual patients or medical conditions, while 
still being able to handle a large number of samples from patients. 
SUMMARY OF THE INVENTION 
The aim of the invention, in general, therefore is to provide an analytical 
system which takes account of these requirements by being able to process 
a large number of samples for analysis with great flexibility with regard 
to the analytical profile applied to the individual sample. More 
particularly, the aim is to provide a processing station for an 
aforementioned analytical system. 
This is achieved according to the invention by providing means for removing 
individual cuvettes from the conveyor, for transferring the individually 
to the position for processing and for returning the cuvettes to the 
conveyor after processing. 
Preferably the aforementioned means comprise a change-over and positioning 
device and a device for simultaneously controlling the positions of the 
change-over and positioning device and controlling a mixing process during 
processing. 
The processing station according to the invention is of use in an 
analytical device which is described in the simultaneously-filed European 
patent application No. 92.105903. Reference is hereby made to this 
description.

DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS 
A circular rotor 2 shown in FIGS. 1 and 2 and rotatable by a drive (not 
shown) through exact angular steps in both directions of rotation, serves 
as a transport magazine for cuvettes 1. The cuvettes 1 are held at the 
outer edge of the rotor, in that they have a flange 1' on their top 
surface which rests on a flat annular surface at right angles to the rotor 
axis, and simultaneously one wall surface of each cuvette abuts the 
substantially cylindrical outer surface of the rotor, and also resilient 
tongues 3 are associated with each cuvette position and extend radially 
over the cuvette and to this end, on their underside, have a projection 
(not shown) which engages in a recess in the cuvette flange 1'. The 
resilient holder holds the cuvettes so that they cannot fall out even when 
the rotor rotates. On the other hand, by means of the resilient holder, 
the cuvettes can easily be removed or inserted manually or by a mechanical 
gripping mechanism. 
A detailed description of the rotor and the operation thereof is given in 
the simultaneously filed European patent application No. 92.105902. 
Reference is hereby made to this description. 
A processing station W is disposed in an exactly defined position relative 
to the rotor 2. In the present embodiment, the processing station is for 
adding reagents to the samples in the cuvettes and mixing the reagents 
with the samples. The processing station substantially comprises a mixing 
device 7 and a change-over and positioning device 4 for transferring the 
cuvettes from the rotor to a pipetting and mixing position and back to the 
rotor. 
Other processing stations arranged and equipped according to the same 
principle are used e.g. for introducing samples into the cuvettes, for 
certain measurements, for incubation etc. 
The mixing device 7 moves the cuvette along a mixing curve 6, after the 
device 4 has brought the cuvette into the pipetting and mixing position. 
To this end, the device 4 is constructed so that the parts thereof holding 
the cuvette are driven in substantially elliptical motion corresponding to 
the mixing curve 6. This will be explained in detail in the following 
description. 
A servomotor 8, which controls all operating sequences, is disposed below a 
stationary baseplate 10. The servomotor 8 has a shaft 9 extending through 
the baseplate 10 and bearing a control disc 11 which comprises a cam 12 
and a groove 13. The control groove 13 has a substantially spiral shape 
and extends over an angle of about 360.degree. from the centre of the 
control disc to near the periphery thereof. A cam roller 15 is disposed in 
the control groove and is rotatably mounted on a push rod 16. The push rod 
16 is non-rotatably connected to a slide 17 which slides along a straight 
line on a guide 18 in a substantially radial direction towards the rotor 
2. The guide 18 is part of a swivel arm 19. The direction of motion of the 
slide 17 is shown by an arrow 21 for motion towards the rotor and 29 for 
motion away from the rotor. 
Another cam roller 22 is rotatably mounted on a crank arm 23 and positioned 
so that during a certain angular rotation of the control disc 11, the 
roller 22 is guided along the outer surface of the cam 12. The crank arm 
23 is integral with a shaft 24 which is mounted for rotation in two struts 
20 which extend vertically from the slide 17. At its other end, the shaft 
24 bears a lever-like gripper 25. When the cam roller 22 and the crank arm 
23 are moved outwards by the cam 12, the shaft 24 rotates and raises or 
lowers the gripper 25. 
On its underside, the gripper 25 bears a cam 26 which is dimensioned so 
that it can engage in the recess in the flange on the cuvette. 
A spiral spring 53 is clamped against an abutment under the other end of 
the gripper and ensures that the gripper is always in a "closed" 
inoperative position when not actively opened. 
An anvil 27 is disposed below the gripper 25 and, on its side facing the 
rotor 2 and cuvettes 1, has an end face profiled to correspond to the 
shape of the cuvette, the top surface of the end face being exactly level 
with the annular surface on which the cuvette flange bears on the rotor. 
The anvil 27 co-operates with the gripper 25. These two parts hold a 
cuvette, so as to remove it from the rotor and transfer it to the 
pipetting and mixing position 5. In position 5, the cuvette is at the 
place where a pipetting syringe 31 (FIG. 2) is lowered into the ejection 
position inside the cuvette. 
In addition to the previously mentioned spiral groove 13, the control disc 
has a central bore 32 which is deeper than the spiral groove and is 
disposed at the inner end thereof, eccentrically relative to the shaft 9. 
An electromagnet 34 disposed on the slide moves a hammer 36, via a linkage 
35, into a top and a bottom position. In the bottom position the hammer 36 
presses the push rod 16 and consequently the cam roller 15 into the 
central recess in the control groove, against the pressure of a helical 
spring 42 disposed between the bearing and the head 43 of the push rod 16. 
In its top position, the hammer 36 release the head 43 of the push rod 16. 
A rotation pick-up 44 is disposed on the periphery of the control disc 11 
and responds to as part of the disc, e.g. to a vane 40 disposed on it and 
used for resetting the control disc 11. 
The swivel arm 19 is mounted for rotation around a shaft 41 permanently 
connected to the baseplate 10. A helical spring 48 is disposed between the 
arm 19 and a bracket 47 and is laterally offset from the shaft 41. As a 
result of the lateral offset, the spring exerts a torque on the arm 19, 
thus forcing it into a defined inoperative position. The inoperative 
position is defined so that in it, the change-over and positioning device 
moves exactly radially towards the rotor. It also helps to introduce the 
cam roller 15 into the control cam 13 after it has been raised from the 
bore 32 during the change in direction of rotation from anti-clockwise 28 
to clockwise 14. 
The slide 17 has an additional guide in the form of a vertical guide plate 
45 and two guide pins 46. 
A light barrier is disposed in a fixed position relative to slide 17 and 
arm 19 and detects the presence or absence of a cuvette. If no cuvette has 
been gripped, the fault is reported to the system, after which appropriate 
action is taken. 
The purpose and co-operation of the aforementioned components is as 
follows: 
While the rotor 2 is stationary, the change-over and positioning device 4 
takes a cuvette 1 from the rotor 2 (FIG. 1) and transfers it to a 
pipetting position 5 (FIG. 2). 
The needles 31 are then used for pipetting and simultaneous mixing by 
closed shaking movements in the form of a mixing curve 6 generated by the 
mixing device 7 as described hereinafter. During the mixing operation, the 
pipetting needle remains inserted in the cuvette and delivers the reagents 
to be pipetted. Mixing is particularly efficient if simultaneous with 
pipetting. 
Next, the cuvette 1 filled with the mixture is returned by the device 4 to 
the rotor magazine 2, which conveys the cuvette 1 to other working 
stations. 
The device 4 and the mixer 7 are driven by a common motor 8. The cuvettes 1 
are taken from rotor 2 as follows: 
The motor 8, via the shaft 9, drives the control disc 11 comprising the cam 
12 and the spiral groove 13. 
When the control disc 11 rotates anticlockwise 28, the roller 15, push rod 
16, slide 17 and device 4 are moved on the guide 18 of the swivel arm 19 
in the direction 21 towards the rotor 2 (FIG. 1) via a straight, radially 
outwardly acting portion 13' of the control groove 13. 
At the same time, the cam 12 acts on roller 22 via the crank arm 23 and 
shaft 24 so as to open the gripper 25 of the change-over and positioning 
device 4. After device 4 reaches its foremost position, the cam part 12' 
closes the gripper 25 under the action of spring 53. The cam 26 and anvil 
27 grip the flange 1' of the cuvette 1. 
Next (point P on the control cam 13, 13'), the push rod 16, cam roller 15 
and spiral groove 13 move the slide 17 and device 4 from the rotor 
magazine 2 in the direction 29 and thus transfer the cuvette 1 from the 
range of operation of rotor 2 to the pipetting and mixing position 5 (FIG. 
2). 
In position 5, one or more pipettes 31 can be used for pipetting with 
simultaneous or subsequent mixing by shaking. The mixer drive operates as 
follows: 
In the pipetting and mixing position 5 in FIG. 2, the cam roller 15 is at 
the inner end of the control groove 13 and initially is exactly above the 
bore 32, which is eccentric (e) relative to the centre 33 of the shaft 9. 
The electromagnet 34, the linkage 35, the hammer 36 and the push rod 16 
insert the cam roller 15 into the eccentric bore 32 below the level of the 
control cam 13. The bore 32, which is disposed in the control disc 11 and 
is eccentric (e) relative to the shaft 9, additionally rotates in the 
direction 28, resulting in a circular, eccentric drive 37 of the cam 
roller 32 and push rod 16 around a diameter 2e (FIG. 3), thus generating 
two superposed shaking and mixing sequences, i.e. a linear oscillating 
mixing motion in a direction 38 along the guide 18, and an oscillating 
pivoting motion 39 around the shaft 41 of the swivel arm 19. The two 
motion sequences 38 and 39 overlap at the pipetting and mixing position 5 
to form an elliptical mixing curve 6. 
During mixing, the cam roller 22 is outside the range of action of the 
control cam 12, and is thus positioned above the disc 11 in a radially 
inner position relative to the cam (FIG. 2). 
The spring 42 biases the push rod 16 so that during mixing the push rod 
always remains vertical with its head 43 against the hammer 36, but can 
move freely horizontally under the hammer in the directions 38 and 39 
(FIG. 2). 
After pipetting and mixing, the filled cuvette 1 is returned to the rotor 2 
as follows (FIG. 1): 
The electromagnet 34 after actuation, the linkage 35 and the spring 42 
raise the hammer 36, so that the push rod 16 and roller 15 are raised 
vertically out of bore 32 to the level of the control cam 13. The 
direction of rotation changes to clockwise 14. The cam roller 15 engages 
the control groove 13 and, via the push rod 16, guides the slide 17 and 
the change-over and pipetting device 4 along the guide 18 in the direction 
21 towards the rotor 2. 
In the process the cuvette 1 is delivered to the rotor 2, and meanwhile the 
cam roller 22 has run up to the cam part 12' and opens the gripper 25 via 
the crank 23 and shaft 24. 
By means of the straight curve portion 13', the change-over and positioning 
device 4 is then moved a distance from the rotor 2 and consequently out of 
its range of action. 
The rotor then moves to the next position, e.g. to transfer the cuvette to 
another station and bring a new cuvette 1 to the pipetting and mixing 
position. The sequence of operations recommences as described.