JPH01209362A - Automatic sample introducing apparatus - Google Patents

Abstract

PURPOSE:To enable handy detection of abnormality in a moving member under an open loop control, by comparing the number of pulses between incoming and outgoing paths for pulse signals of a pulse motor which drives the moving member for a sample suction needle. CONSTITUTION:A moving member 11 movable in the Z axis with a sample suction needle 10 is mounted on a moving member 12 movable in the X axis in such a manner as to be movable in the Y axis as well. The movement of the moving members 11 and 12 is performed with respective pulse motors. The moving members 11 and 12 are provided with a home position sensor 1 to detect respective home positions in the X, Y and Z axes. The number of pulses stored in an outgoing path number of pulses memory means 4 is compared with that of a incoming path number of pulses memory means 5. When the different therebetween exceeds a fixed value, a comparison means 6 outputs a signal to display an error message on a display means 7 or to stop analysis.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an automatic sample introduction device for an analytical instrument such as a liquid chromatograph.

(Prior art) In an automatic sample introduction device (autosampler) for liquid chromatography, sample bottles and sample containers are arranged on a rack or turntable, and when introducing a sample, a sample suction needle is placed in 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.

The automatic sample introduction device has a moving member that moves the sample suction needle in three-dimensional directions (X direction, Y direction, and two directions) and moves it up and down, as well as a moving member that operates the microsyringe that aspirates the sample. There are various moving members, such as a moving member and a moving member for rotating a six-way valve.

Many of these moving members are driven by pulse motors (step motors).

When driving the moving member with a pulse motor, open loop control is the cheapest method.

(Problem to be Solved by the Invention) After the sample suction needle is moved horizontally to a position above a predetermined sample bottle, etc., it is lowered vertically and inserted into the sample bottle. If resistance increases in the part that moves the sample suction needle in the horizontal direction due to changes in the moving mechanism over time, the sample suction needle cannot be inserted accurately into the center of the sample bottle, etc. Accidents such as hitting the edge of a vehicle occur.

When a pulse motor is used under open-loop control, it is not easy to know that a moving member has malfunctioned.

The present invention provides an automatic sample introduction device equipped with various types of moving members, which is equipped with a simple device that can detect malfunctions of the moving members when the moving members are driven by open loop control using a pulse motor. The purpose is to provide an introduction device.

(Means for Solving the Problems) FIG. 1 shows the present invention with respect to one moving member.

1 is a home position sensor that detects the home position of the movable member; 3 is a pulse motor control means that sends a pulse signal to the pulse motor drive circuit 2; and 4 is a pulse motor controller that detects the number of pulses when the movable member moves from the home position to a specified position. A forward pulse number storage means 5 stores the number of pulses inputted from the pulse motor control means 3 and stores the number of pulses when the moving member moves from a specified position to the home position, and the number of pulses from the pulse motor control means 3 and the home position sensor 1 return pulse number counting means for counting from the output signal of the
Comparison means 6 compares the number of pulses stored in the forward pulse number storage means 4 and the counted pulse number of the backward pulse number counting means 5, and outputs a signal when the difference exceeds a certain value. Depending on the output signal of the comparison means 6, for example, an error message is displayed on the display means 7 or the analysis is stopped.

(effect) The present invention will be explained in detail with reference to FIGS. 2 and 3.

An example will be explained in which the present invention is applied to an X-direction moving member that moves a sample suction needle in the X-direction.

In order to move the sample suction needle in the X direction by the pulse motor, a pulse signal for driving the pulse motor 8 is applied from the pulse motor control means 3 to the pulse motor drive circuit 2 (step s1).

The pulse number A at this time is stored in the forward pulse number storage means 4.

When the sample suction operation is completed, an operation is performed to return the sample suction needle to the home position. At this time, a pulse signal for rotating the pulse motor 8 in the reverse direction is sent from the pulse motor control means 3 to the pulse motor drive circuit 2, but after sending out the pulse signal, it is determined that the sample suction needle has returned to the home position. The number of pulses until the sensor 1 detects the number of pulses is counted by the forward pulse number counting means 5.
Count by

In the counting operation, as shown in FIG. 3, the pulse number B is first cleared to 0 (step S2).

Each time a pulse is given to the pulse motor, 1 is added to the pulse number B in the memory device, and the pulse sending is stopped when the home position sensor 1 detects that the sample suction needle has returned to the home position. (Step S3
．． S4. S5).

The pulse number B counted in this way is compared with the pulse number A stored in the forward pulse number storage means 4 by the comparison means 6 (step S6), and if the difference is less than a certain value, the pulse motor is It is assumed that the sample suction needle has reached the predetermined X position without step-out, and the process proceeds to the next sample suction operation (step S7).

However, if the difference between the two pulse numbers becomes larger than a certain value, it can be determined that the pulse motor has lost synchronization, so the comparison means 6 generates a signal indicating that the operation related to the movement in the X direction is not normal (step S8). In response to a signal indicating the malfunction, the direction (X) in which the error has occurred is displayed on the display means 7, such as a CRT, and the analysis operation is interrupted.

Although the movement of the sample suction needle in the X direction has been described, the same applies to movement in the Y direction and two directions, and the operation is also similar when the present invention is applied to other moving members.

(Example) FIG. 4 shows an example of an automatic sample introduction device to which the present invention is applied.

10 is a sample suction needle, which is attached to the moving member 11. The movable member 11 is movable in the X direction (vertical direction) and is attached so as to be movable in the Y direction along the movable member 12. The moving member 12 can move in the X direction.

Movement of moving member 11 in the Y direction and X direction, moving member 12
The movement in the X direction is driven by each pulse motor via a power transmission mechanism. The moving members 11 and 12 are provided with home position sensors (paths shown), such as photo sensors, for detecting the respective home positions in the X direction, the Y direction, and the X direction.

13 is a sample rack, and a plurality of sample bottles 14 are arranged in the sample rack 13.

15 is an injection port for injecting a sample into the liquid chromatograph. The injection port 15 is attached to a high-pressure six-way valve (path shown), through which the sample is sampled and introduced into the column. The hexagonal valve is also driven by a pulse motor, and the present invention is applied thereto.

Furthermore, a microsyringe (the path shown) is provided for inhaling the sample from the sample inhalation needle 10, and the microsyringe is also driven by a pulse motor, to which the present invention is applied.

FIG. 5 shows a control system of one embodiment.

Reference numeral 20 denotes a microcomputer system, which realizes the functions of the pulse motor control means 3, the forward pulse number storage means 4, the backward pulse number counting means 5, and the comparison means 6 in FIG.

In order to move the moving members 11, 12 in the X direction, the Y direction, and the X direction, respective pulse motors 2LX, 21Y,
212 are provided, each pulse motor drive circuit 2
2X, 22Y, and 22Z are connected to a microcomputer system.

Home position sensors 23Z, 23Y, and 23Z are connected to the microcomputer system 20 to detect home positions of the moving members 11 and 12 in the X direction, Y direction, and two directions, respectively.

Further, a drive circuit 25 that drives a pulse motor 24 that operates the six-way valve is also connected to the microcomputer system, and a home position sensor 26 that detects the home position of the six-way valve is also connected to the microcomputer system 20.

Furthermore, a drive circuit 28 that drives a pulse motor 27 that operates a microsyringe that aspirates a sample is also connected to the microcomputer system 20, and a home position sensor 2 that detects the home position of the microsyringe.
9 is also connected to the microcomputer system 20.

In the embodiment shown in FIG. 5, five pulse motors are provided for the moving member, and each pulse motor 21X, 2IY, 212,
The functions shown in FIG. 1 are realized for each of 24 and 27.

(Effects of the Invention) In the present invention, when moving a movable member from its home position to a predetermined position, the number of pulses of the pulse signal of the pulse motor that drives the movement is compared in the outward and return directions, and the difference in the number of pulses is determined. Since a signal indicating an abnormality is output when the pulse motor exceeds a certain value, an abnormality in the moving member can be detected even though the pulse motor is under open loop control.

Since the pulse motor is used under open-loop control, the automatic sample introduction device becomes inexpensive.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the present invention, FIGS. 2 and 3 are flowcharts showing the operation, FIG. 4 is a perspective view showing an example of an automatic sample introduction device to which the present invention is applied, and FIG. FIG. 2 is a block diagram showing a control system of one embodiment. 1... Home position sensor, 2...
- Pulse motor drive circuit, 3... Pulse motor control means, 4... Forward pulse number storage means, 5.
... Return pulse number counting means, 6 ... Comparison means, 8 ... Pulse motor. Patent applicant: Shimadzu Corporation

Claims (1)

[Claims] (1) In an automatic sample introduction device that is equipped with a member that moves under open-loop control of a pulse motor and sucks in a sample from a sample bottle or the like and introduces the sample into the sample introduction section of an analytical instrument, the home position of the moving member is detected. a home position sensor that sends a pulse signal to a pulse motor drive circuit; a pulse motor control means that inputs and stores the number of pulses when the moving member moves from the home position to a specified position from the pulse motor control means; a forward pulse number storage means; a return pulse number counting means for counting the number of pulses when the movable member moves from a designated position to a home position based on the number of pulses from the pulse motor control means and the output signal of the home position sensor; , comprising comparison means for comparing the stored pulse number of the forward pulse number storage means and the counted pulse number of the return pulse number counting means and outputting a signal when the difference exceeds a certain value. Automatic sample introduction device.