JPS6291818A - Constant rate pump - Google Patents

Abstract

PURPOSE:To enable the liquid suction of high accuracy by performing a closed loop control by detecting the suction quantity. CONSTITUTION:A computer 6 reads out the output of the photosensor alley 4 prior to the suction via a driver 5 and stores the output pattern thereof. The driving command is then outputted from the computer 6 to a pump control device 7, a pump 1 is actuated by the device 7 and the liquid is sucked into the suction pipe 2. The computer 6 reads the output of the sensor alley 4 at the prescribed intervals after outputting the driving command. The height of the liquid level inside the pipe 2 is calculated from the comparison result of the output pattern thereof with the output pattern stored prior to the suction. By performing the comparison of this height with the preset target value and the control of the pump 1 is performed until the calculated height reaching to the target value. By measuring the height of the liquid level inside the pipe 2 with high accuracy by such optical detecting device the closed loop control is performed under detecting the suction quantity and the liquid suction of high accuracy is made possible.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to high precision metering pumps. More specifically, the present invention relates to a pump that can transfer liquid from one container to another with high precision and quantitative properties in the fields of chemistry, biochemistry, etc.

BACKGROUND OF THE INVENTION Various pumps are used in the fields of chemistry, biochemistry, etc.

FIGS. 5 to 7 show pumps that have conventionally been widely used in these fields. The pump shown in FIG. 5 is a peristaltic pump, in which an elastic tube 51 is contracted using the rotation of a roller 52, and liquid is sucked by the negative pressure generated thereby. In this pump, since the rotation angle of the roller 52 and the amount of suction are in a proportional relationship, the amount of suction can be easily controlled.

However, the elasticity and non-uniformity of the tube 510 cause errors in the amount of liquid within the tube 51, making highly accurate suction impossible.

The pump shown in FIG. 6 uses suction from an air pump 61 to create a negative pressure in the syringe 62 and suck the liquid, but there is a problem that the air pressure also fluctuates when the temperature changes. If this changes, an error will occur in the amount of suction, so highly accurate suction cannot be expected.

Further, FIG. 7 shows a syringe pump used for high-precision suction. The suction amount is controlled by the movement stroke of the plunger 71. However, normally, some air is present in the syringe 72, and as in the case of an air pump, the air pressure changes due to temperature fluctuations, and the correspondence between the stroke amount of the plunger 71 and the suction amount becomes incorrect. There was a problem in that accuracy deteriorated.

On the other hand, in the above fields, for example, when detecting the amount of antibodies produced by a certain type of cell and comparing the antibody production ability, it is necessary to aspirate Tsuchiura solution in a culture container with precision on the μm order. There is, but often.

Problems to be Solved by the Invention However, the above-mentioned pumps are unable to perform suction with high precision required in fields such as biochemistry.
We were unable to adequately respond to such requests.

In the case of any of the conventional pumps shown in Figures 5 to 7, the oven loop control that does not detect the actual suction amount is fatal, and this is due to the elasticity and non-uniformity of the tube, and the air pressure. This is because even if an error occurs in the suction amount due to various causes such as fluctuations in the amount of suction, it could not be detected.

Therefore, the present invention aims to provide a metering pump that can realize highly accurate suction by detecting the amount of suction and performing closed-loop control.

Means for Solving the Problems Therefore, in view of the above-mentioned objective, the present inventor investigated a suction amount detection method necessary for closed-loop control that enables highly accurate suction. As a result, we succeeded in developing a unique optical detection method that can meet these requirements. In other words, while a conventional pump is used to suck liquid into a transparent pipe, the pipe is used as a lens to illuminate the pipe with a parallel beam of light, and the transmitted light is detected by a photosensor array. The height of the liquid level in the pipe can be determined from the signal.

The present invention realizes a highly accurate pump by utilizing such unique optical detection technology. That is, the metering pump of the present invention includes a suction pipe made of an optically transparent body, a pump that sucks the liquid to be metered into the ΔH suction pipe, and an optical system that irradiates the suction pipe with a parallel light beam. a photosensor array that detects light transmitted through the suction pipe, and receiving a detection signal from the photosensor array to determine the height of the liquid level in the suction pipe;
It is characterized by comprising a pump control means that operates the pump until the height of the liquid level reaches a predetermined value, and stops the pump when the height of the liquid level reaches a predetermined value.

In a preferred embodiment of the present invention, the pump control means detects the height of the liquid level in the suction pipe by comparing the output patterns of the photosensor array before and after liquid suction.

-effect A method for detecting the height of a liquid level according to the present invention will be explained.

As shown in Fig. 2, a suction pipe 2 made of transparent material
A one-dimensional photosensor array 4 is disposed with a photosensitive section facing the longitudinal direction of the suction pipe 2 so as to irradiate a parallel light beam onto the suction pipe 2 and receive the transmitted light. In this way, suction pipe 2
The transmitted light is observed simultaneously over the length of the photosensitive portion of the photosensor array 4 along the longitudinal direction. As the suction pipe 2, a cylindrical pipe with a uniform inner diameter and wall thickness in the longitudinal direction is used. Then, the curvature surface of the suction pipe 2 acts as a condensing lens, and the parallel light beam irradiated onto the suction pipe 2 is refracted by the suction pipe 2 and then tries to be condensed behind the suction pipe 2.

Therefore, as shown in FIG. 3(a), with air in the suction pipe 2, the photosensor array 4 is placed at a position where the parallel light beam is condensed. ) The positional relationship should be adjusted so that the output of the photosensor array 4 is maximized.Of course, spherical aberration and the temperature of the adhering water will affect the image sensor. It is difficult to focus the light. However, the third
As shown in Figure 3(b), when the liquid is sucked, the refractive index inside the suction pipe 2 changes, so the parallel light beam is not focused on the photosensor array 4, and as shown in Figure 3(a). The output of the photosensor array 4 is lower than in the case shown in FIG.

Therefore, in an ideal case, when only air enters the suction pipe 2, the output of the photosensor array 4 exhibits a high value and a flat shape as shown in FIG. 4(a).

However, when a part of the liquid is sucked into the suction pipe 2, the parallel light beam is not focused on the photosensor array 4 only in the liquid part, so the output level is lower than that in the liquid part, as shown in FIG. 4(b). It is low and has a step-like shape with a high air section. Therefore, the stepped portion of the output waveform indicates the liquid level, and thereby the height of the liquid level can be detected.

In reality, liquid adheres to the inner wall of the pipe, making the light condensing condition worse, and the output of the photosensor array 4 may be disrupted as shown in Figure 4 (C) even though no liquid is being sucked. . However, by memorizing this output pattern before suctioning the liquid and comparing it with the output pattern after suction as shown in FIG. 4(d), it is possible to always detect a change in the output.

From the height of the liquid level obtained in this way and the inner diameter of the pipe, the liquid suction barrier can be calculated. As a means of realization, the parallel light beam can be realized without any problems using optical systems of the prior art. As the pump for sucking the liquid, the Verisf pump, air pump, syringe pump, etc. shown in FIGS. 5 to 7 can be used.

Note that the photosensor array 4 may be arranged at a position where the parallel light beam is focused while the liquid is being sucked into the suction pipe 2. However, in this case, when some liquid is sucked into the suction pipe 2, the photosensor array 4
Contrary to FIG. 4(b), the output is high in the liquid portion and low in the air portion.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a block diagram of a metering pump according to an embodiment of the present invention. Liquid is sucked into a suction pipe 2 by a pump 1. In order to detect the position of the liquid level in the suction pipe 2, the suction pipe 2 is irradiated with a parallel beam of light from the optical system 3, and the one-dimensional photosensor array 4 detects the transmitted light. A driver 5 is connected to the output terminal of the photosensor array 4, and a computer 6 is connected to the output terminal of the driver 5.

A pump controller 7 is connected to an output terminal of the computer 6, and an output terminal of the pump controller 7 is connected to the pump 1. The pump 1 is a conventional valve pump and is powered by a pump controller 7 to draw liquid into a suction pipe 2 connected to the pump 1.

The suction pipe 2 is, for example, a cylindrical pipe made of glass, and is irradiated with a parallel light beam perpendicularly to the longitudinal direction of the suction pipe 2 by an optical system 3 consisting of a light source and a condensing lens. In the case of this example, a glass cylindrical pipe with an inner diameter of 2 mm was used.

A one-dimensional photosensor array 4 is arranged on the opposite side of the optical system 3 with respect to the suction pipe 2 . This photosensor array 4 is a linear sensor array in which sensor elements are arranged in a straight line parallel to the suction pipe 2.

In this example, a linear sensor array with each pixel of 20 μm and 2000 pixels was used.

The photosensor array 4 is disposed at a position where the parallel light beam from the optical system 3 is refracted and condensed by the curvature of the suction pipe 2 when only air enters the suction pipe 2.

Further, the photosensor array 4 is scanned by the driver 5 and its output signal is amplified. When the computer 6 stores the output pattern P1 of the photosensor array 4 before liquid suction, it outputs a drive command to the pump controller 7,
Output pattern P of photosensor array 4 during liquid suction
2 and the above output pattern P1, and further calculates the height of the liquid level in the suction pipe 2 from this comparison result, and when this height reaches the target value, outputs a stop command to the pump controller 7. It is made to be.

When a drive command is input from the computer 6, the pump controller 7 outputs the power necessary for driving to the pump 1 to operate the pump 1, and when a stop command is input, the pump controller 7 stops the supply of power and stops the pump 1.

Next, the operation of this embodiment will be explained.

First, the computer 6 uses the photosensor array 4 before suction.
The output pattern PI is read through the driver 5 and the output pattern PI is stored. Next, the computer 6 outputs a drive command to the pump controller 7, and the pump controller 7 outputs the power necessary for driving to the pump 1, so that the pump 1 is started and liquid is sucked into the suction pipe 2. After outputting the drive command, the computer 6 reads the output of the photosensor array 4 at predetermined sampling intervals, and compares this output pattern P2 with the output pattern P1 stored before suction. Furthermore, the height of the liquid level in the suction pipe 2 is calculated from the comparison result, and this height is compared with a preset target value.

In this way, when the calculated height has not reached the target value, the next sampling is waited for, and when the calculated height has reached the target value, a stop command is output to the pump controller 7. The pump controller 7 that has input the stop command stops the power supply to the pump 1, and the pump 1 stops sucking the liquid.

In this way, a glass cylindrical pipe with an inner diameter of 2 mm is used as the suction pipe 2, and each pixel of the photo sensor array 4 is 20 μm.
In this example using a linear sensor array with m1 total image count of 2000, the amount of liquid up to 125μβ is 0.06μl.
It was possible to aspirate with a precision of

Output pattern P2 and output pattern P1 memorized before suction
It is more preferable to compare each pixel. That is, when looking at each pixel, when the level of the output pattern P2 is lower than the level of the stored output pattern P1, as described above, the part of the pipe corresponding to the pixel is filled with liquid, When the level of the output pattern P2 is almost the same as the level of the output pattern P1 stored in the memory: α, it means that the liquid has not yet reached the part of the pipe corresponding to the pixel, or that there are bubbles in the chin. That is, bubbles in the pipe can also be detected by comparing each pixel.

Therefore, when the number of pixels whose level of the output pattern P2 is lower than the level of the stored output pattern P1 reaches a predetermined number, it is determined that the target value has been reached. By using such a method, even if there are bubbles in the suction pipe, the length of the liquid column excluding the bubbles can be determined, and more accurate liquid volume comparisons can be made.

Note that if there is a clear difference in the output level of the photosensor array 4 before and after suction, there is no need to memorize the output pattern before suction, and you can simply monitor the output level of the photosensor array 4 after suction. It is possible to detect the surface position. Further, the suction pipe can be made of any transparent material other than glass, such as plastic.

Effect of Hakko As explained in detail above, in the suction pump according to the present invention, the amount of suction can be determined by measuring the height of the liquid level in the suction pipe with very high precision using the optical detection device as described above. Since closed-loop control is performed while detecting the Therefore,
For example, the metering pump of the present invention is capable of detecting antibodies with high precision and is extremely useful in fields such as chemistry and biochemistry.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram of a metering pump according to an embodiment of the present invention, Fig. 2, Fig. 3 (a) and (b) are explanatory diagrams showing the principle of the present invention, respectively, Fig. 4 (a) Figure d) is an output waveform diagram of the photosensor array used in the present invention, and Figures 5 to 7 are schematic diagrams showing conventional pumps. Main reference numbers) ■... Pump 2... Suction pipe 3... Optical system 4... Photo sensor array 5... Driver 6... Computer 7... Pump controller 51... Tube 52... Roller 61... Air pump 62.72...Syringe 71...Plunger

Claims (4)

[Claims] (1) A suction pipe made of an optically transparent material, a pump that sucks the liquid to be quantified into the suction pipe, an optical system that irradiates the suction pipe with a parallel light beam, and light transmitted through the suction pipe. a photosensor array that detects the liquid; and a detection signal from the photosensor array is input, the height of the liquid level in the suction pipe is determined, and the pump is operated until the height of the liquid level reaches a predetermined value. and pump control means for stopping the pump when the value reaches a predetermined value. (2) The photosensor array is arranged at a position where the parallel light beam is focused when no liquid is being sucked into the suction pipe. Metering pump. (3) The quantitative determination according to claim 1, wherein the photosensor array is arranged at a position where the parallel light beam is focused when the liquid is sucked into the suction pipe. pump. (4) The pump control means detects the height of the liquid level in the suction pipe by comparing output patterns of the photosensor array before and after liquid suction. or any one of paragraph 3.
Metering pumps as described in Section.