JPS63243881A - Automatic sample injecting apparatus - Google Patents

Abstract

PURPOSE:To improve the reliability of an apparatus by constituting a titled apparatus in such a manner that a sample sucking needle is returned to a home position and a sucking action is carried out again when the sample sucking needle fails to be correctly inserted into a sample bottle, etc. CONSTITUTION:Pulse motors 4X-4Z are driven respectively by the assigned numbers of pulses by a microcomputer system 58 and pulse motor driving circuits 6X-6Z in the case of executing sample injection. The sample sucking needle 2 comes into contact with the cap of the sample bottle when the needle 2 fails to be correctly lowered into the sample bottle. Then, a spring 22 shrinks and an actuator 26 enters the inside of a sensor 24, thereby turning on the sensor 24. The needle 2 is returned upward in this case. Said needle is returned to the home position in X- and Y-directions as well. The numbers of the pulses applied to the motors 4X, 4Y before the home position sensors 10X, 10Y operate are measured. The measured number of the pulses and the number of the pulses applied previously to the motors 4X, 4Y are compared and the pulse rates to be applied to the motors 4X, 4Y are decreased. The injection action is thus carried out again.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an automatic sample injection 'JA' device for analytical instruments such as liquid chromatographs.

(Prior art) In an automatic sample injection device (autosampler) for liquid chromatography, sample bottles and sample containers are placed on a rank or turntable, and when injecting a sample, a sample suction needle is inserted into a predetermined sample bottle, etc. The sample is inserted into the sample suction needle using the microsyringe. The inhaled sample is injected in the required amount into the channel of the liquid chromatograph via a high-pressure six-way valve.

(Problem to be solved by the invention) After moving the sample suction needle horizontally to a position above a predetermined sample bottle, etc., the sample suction needle is lowered vertically and inserted into the sample bottle etc. However, if resistance increases in the part that moves the sample suction needle in the horizontal direction due to changes over time in the mechanism that moves the sample suction needle, for example, it may become difficult to insert the sample suction needle accurately into the center of the sample bottle, etc. Failure to do so may result in an accident in which the sample suction needle hits the edge of the sample bottle, etc. At this time, if the torque of the pulse motor that lowers the sample suction needle is large, the sample suction needle will be bent.

The present invention allows the sample suction needle to be accurately moved to the center of the sample bottle, etc., and inject the sample without malfunctioning, even if the mechanism that moves the sample suction needle to the upper part of the sample bottle, etc. in a predetermined position changes over time. The purpose of this invention is to provide an automatic sample injection device that can perform the following steps.

(Means for Solving the Problems) A case will be described in which the present invention is applied to a method of arranging sample bottles in a sample rack with reference to FIG.

2 is a sample suction needle, and three pulse motors 4X, 4Y, and 4Z move it in the X direction, Y direction, and Z direction, respectively.
is provided on the moving mechanism. 6X, 6Y, and 6Z are drive circuits for PA/L/SUMO-14X, 4Y, and 4Z, respectively, into which a pulse signal is input from the pulse motor control means 8, and the pulse motors 4X, 4Y, and 4 are driven according to the pulse signal.
Operate Z.

10X, IOY, and 102 are home position sensors that detect the home position of the sample suction needle 2, respectively.

Reference numeral 12 denotes an abnormality detection means for detecting whether the sample suction needle 2 has correctly reached the sample using a separately provided sensor 14 or from the home position sensor 10Z and the number of pulses of the Z-direction pulse motor 4Z.

16 returns the sample suction needle 2 to the home position when the abnormality detection means 12 detects an abnormality, and the pulse motors 4X and 4
This re-driving means reduces the pulse rate of the pulse signal applied to either or both of Y to perform the injection operation again.

(Example) FIG. 2 represents one embodiment.

The sample suction needle 2 is attached to a moving member 20Y so that it can move in the Z direction (vertical direction), and the moving member 20Y is attached so that it can move in the Z direction and also in the Y direction along the moving member 20X. ing. Moving member 20X
can move in the X direction. X of moving member 20X
The movement of the moving member 20Y in the Y direction and the two directions is performed by pulse motors 4X, 4Y, and 4Z, respectively (Fig. 1).
It is driven from the motor through a power transmission mechanism. moving member 20X,
20Y, 20Z and pulse motor 4X, 4Y.

4Z constitutes a moving mechanism.

The moving members 20X, 20Y, and 20Z are provided with home position sensors (photo sensors) IOX, IOY, and 10Z (FIG. 1) that detect the home position, respectively.

The sample suction needle 2 is moved to the moving member 20Y as shown in FIG.
It is attached to via a spring 22.

The sample suction needle 2 moves in the Z direction together with the moving member 20Y, but when the tip of the sample suction needle 2 hits a fixed object, the spring 22 can be compressed.

A sensor (photo sensor) 24 is provided on the moving member 20Y, and an actuator 26 for the sensor 24 is provided on the sample suction needle 2. When the tip of the sample suction needle 2 hits a fixed object and the spring 22 contracts, the actuator 26
enters the sensor 24, causing the sensor 24 to operate.

28 is a sample rack, and a plurality of sample bottles 30 are arranged in the sample rack 28.

32 is an injection boat for injecting a sample into a liquid chromatograph. The injection port 32 is attached to a six-way valve 34 as shown in FIG. 4, and the six-way valve 34 is provided with a sample loop 36.

38 is a pump that supplies the mobile phase 40, and 42 is a column.

The sample injected from the injection port 32 is temporarily held in the sample loop 36, and by switching the six-way valve 34, the sample in the sample loop 36 is sent to the column 42 together with the mobile phase 40.

Next, FIG. 5 shows a control system of one embodiment.

58 is a microcomputer system, which realizes the pulse motor control means 8, the re-driving means 16, and the abnormality detection means 12 in FIG.

The microcomputer system 58 has RAM 46 and R
OM 48 is connected to CPU 44 via bus 50. Pulse motor drive circuit 6X.

6Y, 6Z are connected to the bus 50 via an interface 52, and home position sensors iox, to
y, ioz are also connected to the bus 50 via an interface 54, and the sensor 14 is also connected to the bus 50 via an interface 56.

Next, the operation of this embodiment will be explained with reference to FIG.

When the power is turned on, the pulse motors 4X, 4Y, and 4Z are driven in respective determined directions, and the sample suction needle 2 is driven by home position sensors IOX and IO that detect the home position.
Wait at the position where Y and 10Z are turned on (step S
l).

When a signal to perform sample injection is given, the pulse motor drive circuits 6X, 6 are sent from the microcomputer system 58.
A pulse signal is given to Y, 6Z, and the pulse motor 4X,
4Y and 4Z are each driven by the designated number of pulses (steps S2, S3, and S4).

When the sample suction needle 2 enters the sample bottle correctly, the sensor 24
is not turned on, the sample is sucked up by a microsyringe (not shown) (steps S5 and S6), the sample suction needle 2 is moved to the position of the injection boat 32, and the sample is transferred from the injection port 32 into the sample loop 36. is introduced (step S7). after that,
Six-way valve 34 is switched to pump sample from sample loop 36 to column 42.

When the sample suction needle moving mechanism is working normally, the loop from step Sl to 87 is repeated, and the sample is sequentially introduced. However, if the pulse motors 4X and 4Y that drive in the X and Y directions are out of step due to resistance in the movement mechanism due to changes over time, and the sample suction needle 2 does not descend into the sample bottle correctly, in step S5 When the sample suction needle 2 descends, the sample suction needle 2 hits, for example, the cap of the sample bottle, and the spring 22 contracts, the actuator 26 enters the sensor 24, and the sensor 24 is turned on. In this case, the sample suction needle 2 is returned upward and also returned to its home position in the X and Y directions (step S8).
. Then, before the home position sensors IOX and IOY operate, the number of pulses given to the pulse motors 4X and 4Y is set to the needle side (step S9), and when the needle is moved from the home position to the position of the sample bottle using this number of pulses, The number of pulses given to the pulse motors 4X, 4Y is compared, and the number of pulses given to the pulse motors 4X, 4 in the direction in which the number of pulses has changed is compared.
It is thought that Y has gone out of step, so the pulse motor 4X
, 4Y is reduced (step 5IO), and the injection operation is performed again.

If the pulse rate of the pulse motor is reduced, the torque of the pulse motor increases, so that it is possible to overcome the increase in resistance of the sample suction needle moving mechanism to some extent and operate correctly.

Instead of using the sensor 24 and actuator 26 as abnormality detection means to detect whether the sample suction needle 2 is correctly inserted into the sample bottle, the number of pulses of movement in the Z direction is counted during downward movement and during upward movement. , an abnormality can also be detected from the difference in the number of pulses. In this case, a thick and rigid sample suction needle 2 is used, and the sample suction needle 2 is directly attached to the moving member 20Y, and the torque of the pulse motor responsible for vertical movement is made small. Therefore, even if the sample suction needle hits the cap of the sample bottle, the sample suction needle will not bend.

In the embodiments, an automatic sample injection device in which sample bottles are placed on a sample rack is shown as an example, but the present invention can also be applied to an automatic sample injection device in which sample bottles are placed on a turntable. can. In the turntable method, the sample suction needle is marked with an X.

Instead of moving in the Y direction, it moves along an arc.

(Effect of J8 Ming) In the present invention, it is detected whether the sample suction needle is correctly inserted into the sample bottle, etc., and if it is not inserted correctly, the sample suction needle is returned to the home position and the suction operation is performed again. Therefore, even if the resistance of the sample suction needle transfer mechanism increases due to changes over time, etc., and malfunctions occur easily,
The reliability of the device can be significantly improved.

Furthermore, even a pulse motor with low torque can be used while maintaining reliability, so the automatic sample injection device becomes inexpensive.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the present invention, Fig. 2 is a schematic perspective view showing the external appearance of one embodiment, Fig. 3 is a perspective view showing a part of the sample suction needle attachment in the same embodiment, and Fig. 4 is a sample FIG. 5 is a block diagram showing an example of a control system in the same embodiment, and FIG. 6 is a flowchart showing the operation of the same embodiment. 2...Sample suction needle, 4X, 4Y, 4Z...Pulse motor, 6X, 6
Y, 6Z...Pulse motor drive circuit, 8...
...Pulse motor control means, 10X, IOY, 10z
...Home position sensor. 12...Abnormality detection means, 14...Sensor, 16...Redrive means.

Claims (1)

[Claims] (1) In an automatic sample injection device that is equipped with a mechanism that moves the sample suction needle three-dimensionally and that aspirates a sample from a sample bottle or the like and introduces it into the sample introduction section of an analytical instrument, the drive source for the mechanism that moves the sample suction needle It is equipped with a pulse motor, and has an abnormality detection means that detects whether the sample suction needle has correctly reached the sample from the amount of vertical movement of the sample suction needle, and a pulse motor that returns the sample suction needle to the home position when an abnormality is detected. An automatic sample injection device characterized by comprising: re-driving means for reducing the pulse rate of a pulse signal applied to a motor to perform an injection operation again.