JPS61126473A - Liquid sample dispenser - Google Patents

Abstract

PURPOSE:To minimize the intrusion depth of a nozzle into a liquid by detecting the height of a liquid level by using two electrodes prior to the intrusion thereof and calculating and controlling the movement of the nozzle in accordance with the detected height. CONSTITUTION:The two electrodes 1 for detecting the liquid level as a means for controlling the intrusion depth of the nozzle 4 is intruded into the liquid. A driving mechanism consisting of an arm 2, a shaft 5, bearings 7, 8, sliding bearings 19, 20, pulse motors 15, 16, etc. as well as a control mechanism 36 for calculating and controlling the extent that the nozzle 4 is ought to move are provided. The rotating pulses of the motors 15, 16 are controlled by the stroke from the top dead point of the nozzle 4 to the liquid level regardless of the difference in the height of the liquid level arising from slight variation in the quantity of sample to stop the nozzle 4 always at the min. required intrusion depth. The accuracy of dispensing the liquid sample is thus improved in automatic analysis, etc.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a liquid sample dispensing device, and particularly to a liquid sample dispensing device provided with a nozzle penetration depth control means for controlling the penetration depth of a nozzle into the liquid. This relates to a sample dispensing device.

[Background of the invention]

In liquid sample dispensing devices used for automatic analysis,
A large number of liquid samples are dispensed using the same nozzle. Therefore, in order to prevent the liquid adhering to the surface of the nozzle from mixing with other liquids, the nozzle is generally cleaned, but a small amount of mixing cannot be avoided. In order to minimize this contamination, it is necessary to keep the depth of penetration of the nozzle into the liquid from the liquid surface to the necessary minimum.

Conventionally, as a nozzle penetration depth control means for controlling the penetration depth of the nozzle into the liquid, the nozzle is made of a metal material, and an electrode electrically insulated from the nozzle is attached to the nozzle tip. The electrical resistance between the nozzle and the electrode, which is infinite, changes to a resistance value determined by the liquid by inserting the nozzle and the electrode into the liquid.By utilizing this fact, the level of the liquid can be adjusted. was detected and controlled the penetration depth of the nozzle.

Also, the nozzle and electrode are lowered at the same time to detect the liquid level, but in order to minimize the penetration depth,
The drive source for lowering the nozzle and electrode must be stopped as soon as possible. A pulse motor is generally used as the drive source that satisfies this requirement, and a slow-up/slow-down drive method is used to minimize the inertial load when stopping and starting. This is the current situation.

Therefore, the above method has the following drawbacks.

This will be explained using FIG.

The nozzle and electrode descend from top dead center to bottom dead center,
At this time, the speed ij of the pulse motor is gradually increased from A' (pps) to B (pps).
) to maintain a constant speed, and from KB (pps) to A (pp
The speed gradually decreases to s) and stops at bottom dead center. Therefore, when the liquid level of the sample in the sample container 1 is detected, the process is stopped. The amount of sample in the sample container 1 varies, and therefore the height of the liquid level is also not fixed. Now, let the heights of the liquid level in the sample container 1 be L+, L2. Let Ls be the time t from when the liquid level is detected until the pulse motor stops.
I+t2+t3t is related to the height of the liquid level (i,=
It is constant at i,=13. The number of pulses of the pulse motor from detecting the liquid level to stopping is calculated by multiplying the sum of the pulse speed (pps) when detecting the liquid level and the pulse speed (pps) when stopping by 2 ( area), the number of rotational pulses of the pulse motor from detecting the liquid level to stopping when the liquid level is at heights I, s, L2, and La is L7.
The number of rotation pulses at 2 o'clock > L, the number of rotation pulses at 2 o'clock is different from the number of rotation pulses at 2 o'clock, and the penetration depth of the nozzle also differs accordingly.1. >At>t. Different penetration depths of the nozzle mean that the amount of sample adhering to the nozzle and the outer wall of the electrode is also different. Therefore, even if the same sample is dispensed, it is possible to put more sample into the sample container 1. The amount to be dispensed differs depending on whether a small amount is added or when a small amount is added.

Current automatic analyzers and the like avoid reducing the amount of sample to a very small amount, and even if the amount of adhesion on the outer walls of the nozzle and electrode is minute, it does not affect the accuracy of analysis and has a significant effect.

[Purpose of the invention]

The present invention has been made in view of the above points, and it is an object of the present invention to provide a liquid sample dispensing device that makes it possible to minimize the depth of penetration of the nozzle into the liquid.

[Summary of the invention]

In order to prevent the penetration depth of the nozzle from varying depending on the height of the liquid level due to the amount of sample as mentioned above,
It is necessary to detect the height of the liquid level before the nozzle enters.

As a means of achieving this, the present invention uses two liquid level detection electrodes to detect the height of the liquid level before entering the nozzle, and at this time, the stroke from top dead center to the liquid level is controlled by the pulse motor. The number of rotation pulses is memorized as the number of rotation pulses, and the number of rotation pulses required for the pulse motor when the nozzle is inserted next time is controlled from the number of rotation pulses required when the electrode is inserted, and furthermore, the number of rotation pulses is slowed down from a few pulses ago to make it easier. It was designed to stop it. If the number of pulses required for this slowdown is kept constant, the speed when the nozzle stops is constant, so the penetration depth of the nozzle will always be constant regardless of the liquid level height, and the nozzle penetration depth will be kept to the minimum necessary. That's why it happens.

[Embodiments of the invention]

The present invention will be explained in detail using FIGS. 1, 2, and 3. An arm 2 to which two electrodes 1 are fixed is fixed to a shaft 5, and the upper part of the shaft 5 is supported by a bearing 7 so as to be rotatable and slidable up and down. The other lower end has a slide bearing 19, and the slide bearing 19 and the shaft 5 are integrally processed so that they can freely slide vertically but rotate together in the rotational direction. A cylinder 21 with a slide bearing 19 fixed inside thereof is rotatably supported above and below by a bearing 17 fixed to a stand 9Vc, and a gear 23 is attached to the lower side. A rack 11, which is a mechanism for moving the shaft 5 up and down, is rotatably attached to the shaft 5, and uses the rotational force of the pulse motor 15 to move up and down through a pinion 13 fixed to the shaft of the pulse motor 15. , and is transmitted to the shaft 5Vc. On the other hand, the mechanism for moving the nozzle 4 up and down is also the same. The arm 3 to which the nozzle 4 is fixed is fixed to a shaft 6, and is supported by a bearing 8 above the shaft 6 so as to be rotatable and slidable up and down.

On the other hand, the lower end has a slide bearing 20 (the slide bearing 20 and the shaft 6 are integrally processed so that they can freely slide in the vertical direction but rotate in the same direction.

A cylinder 34 with a slide bearing 20 fixed inside thereof is rotatably supported above and below by a bearing 18 fixed to a stand 10, and a gear 24 and a pulley 25 are attached to the lower side. A rack 12, which is a mechanism for moving the shaft 6 up and down, is rotatably attached to the shaft 6, and converts the rotational force of the pulse motor 16 into vertical movement via a pinion 14 fixed to the shaft of the pulse motor 16. It is converted and transmitted to the shaft 6. Stand 9 and stand 10 have a mounting plate of 28V.
C is fixed, and gears 23 and 24 mesh with each other. On the other hand, the motor 29 fixed to the mounting plate 28
A pulley 26 is fixed to the shaft, and a timing belt 27 is attached between the pulley 26 and the pulley 25. The rotational force of the motor 29 is transmitted to the boot 725, and further transmitted to the gear 23 via the gear 24. and arm 2 and arm 3
each rotates. The detector 22 determines the rotation angle of the arm 3, but now the ratio between the gear 24 and the gear 23 is determined by the gear 2.
3: Gear 24 = 2: If IVc is set, the rotation angle of arm 2 will be 1/2 of the rotation angle of arm 3.

Moreover, the direction of rotation is opposite.

The operation will be explained below. When the sample table 30 on which a plurality of sample containers 32 containing sample liquid are placed on the same circumference at the same intervals stops at a specified position, the pulse motor 15 rotates and the two electrodes 1 descend. . A voltage (not shown) is applied between the two electrodes 1, and when it enters the liquid level in the sample container 32, a current flows between the two electrodes 1 through the liquid and the pulse motor 15 is activated. It is supposed to stop.

The number of pulses generated by the rotation vc9 of the pulse motor 15 at this time is stored in the control mechanism 36. After that, pulse motor 15
rotates in the opposite direction, and the electrode 1 stops at the top dead center. At this point, the motor 29 rotates, and as mentioned above, the gear 23
: If the ratio is set to gear 24 = 2:1, when nozzle 4 comes over sample container 32, electrode 1 will move to the middle between sample table 30 and reaction table 31 as shown. .

If the tip of the electrode 1 and the tip of the nozzle 4 are kept at the same level, the distance from the top dead center of the nozzle 4 to the liquid level is the same.

In other words, since the strokes are the same, the pulse motor 15
If the same number of pulses as required for rotation are given to the pulse motor 16, the nozzle 4 will also descend by the same distance and enter the liquid surface. However, if the electrode 1 enters the liquid surface at a constant speed and the pulse motor 15 is stopped, the number of pulses can be applied as is, as described above. ) In order to lower the electrode 1, a pulse motor 1 is used to lower the electrode 1.
5 must also slow down and stop. Therefore, as in the conventional example, the number of pulses from when the electrode 1 enters the liquid surface until it stops also differs. In the present invention, depending on the number of pulses required for the electrode 1 to descend, the number of pulses (distance) required from the start of slowdown to the stop on the nozzle 4 side is α1°α2. α3 is the height of the liquid level, ,L,,L,
The control mechanism 36 determines a constant so that it is constant regardless of the
If the control is carried out, the penetration depth of the nozzle 4 is 1. , 1. , 13 are always constant.

As mentioned above, the syringes 35 and 1 are connected to the nozzle 4t/cm, which always has a constant penetration depth regardless of the liquid level height, and sucks the sample in the sample container 32, and then the nozzle 4 rises, rotates, descends into the reaction container 33 on the reaction table 31, and discharges the sample. The above operation is repeated, but when the nozzle 4 comes above the reaction vessel 33, the electrode 1 is on the sample vessel 32, so when the nozzle 4 discharges, the liquid level in the sample vessel after the electrode 1 is This means that the height of the object can be detected.

〔Effect of the invention〕

1. According to the present invention, the amount of penetration of the nozzle into the liquid is controlled to the necessary minimum, and the depth of penetration of the nozzle into the liquid can be minimized.

2. Since the liquid level height of the liquid is detected before the nozzle penetrates into the liquid, a constant and minimum required nozzle penetration depth can be obtained regardless of the liquid level height.

3. By combining the rotational drive source of the nozzle and electrode into one,
The cost can also be reduced.

4. Since the liquid level height can be detected before the nozzle enters the liquid, an alarm can be issued if the sample liquid is too low.

[Brief explanation of drawings]

Fig. 1 is a nozzle penetration depth relation diagram of the conventional method, Fig. 2 is a nozzle penetration depth relation diagram of the present invention, Fig. 3 is a plan view of the present invention, and Fig. 4 is a side view of the present invention. FIG. 1... Electrode, 2... Arm, 3... Arm, 4...
...Nozzle, 5...shaft, 6...shaft, 7...bearing,
8... Bearing, 9... Stand, 10... Stand, 11... Rack, 12... Rack, 13... Pinion, 14... Pinion, 15... Pulse motor, 16 ...Pulse motor, 17...Bearing, 1
8...Bearing, 19...Slide bearing, 20.
...Slide bearing, 21...Cylinder, 22...Detector, 23...Gear, 24...Gear, 25...P--
26...Pulley, 27...Timing belt,
28... Mounting plate, 29... Motor, 30... Sample table, 31... Reaction table, 32... Sample container, 33... Reaction container, 34... Cylinder, 35...・
Syringe, 36...control mechanism. .

Claims (1)

[Scope of Claims] 1. A container containing a sample liquid, a liquid suction and discharge mechanism that suctions and discharges the liquid in the container through a nozzle into a reaction container, and a liquid suction and discharge mechanism that is directly connected to the nozzle and connects the nozzle to the container. and a nozzle drive mechanism for driving the nozzle inside and toward the reaction vessel, the nozzle drive mechanism being provided with nozzle penetration depth control means for controlling the penetration depth of the nozzle into the liquid in the vessel. In the liquid sample dispensing device, the nozzle penetration depth control means includes a drive mechanism for causing two electrodes to penetrate into the liquid, a drive mechanism for causing the nozzle to penetrate into the liquid, and a movement amount of the electrodes. A liquid sample dispensing device comprising: a calculation control mechanism that calculates and controls the amount of movement of the nozzle; 2. The liquid sample dispensing device according to claim 1, characterized in that there is one rotational drive source for driving the nozzle and the electrode toward the container and the reaction container.