JPH09264772A - Dispensing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately calculate a suction amount and discharge amount by directly monitoring liquid level in a nozzle. SOLUTION: A nozzle 10 has a nozzle base 12 and a nozzle tip 14. An ultrasonic sensor 18 is provided at the base 12. The liquid level of sample in liquid is detected by the sensor 18. Since the ultrasonic wave is transmitted and received in the nozzle 10, the convergence of the ultrasonic wave can be enhanced, and external noise can be shut off. The suction amount and, discharge amount can be calculated, liquid leakage can be discriminated and suction failure is discriminated based on the level detected result.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sample suction device, and more particularly to liquid level detection using ultrasonic waves in an automatic dispensing device.

[0002]

2. Description of the Related Art A dispensing device is a device for sucking a sample from a sample container containing a sample (original sample) and distributing the sucked sample to a plurality of containers. In such a dispensing device,
Suction / discharge of the sample is performed by a nozzle connected to a dispensing pump that generates suction pressure and discharge pressure via an air tube. 2. Description of the Related Art In recent years, a nozzle in which a nozzle tip made of resin or the like is mounted on a nozzle base made of metal and the nozzle is made partially disposable has become popular. In the present specification, for convenience, a device that only sucks a sample is included in the concept of the dispensing device.

In order to improve the dispensing accuracy in the dispensing apparatus, it is necessary to accurately manage the liquid amount of the sample sucked by the nozzle (suction amount) and the liquid amount of the sample discharged from the nozzle (discharge amount). Therefore, conventionally, it has been proposed to transmit light along the longitudinal direction of the nozzle and monitor the liquid amount based on the change in the transmitted light amount.

[0004]

However, in the above-mentioned conventional liquid amount monitoring utilizing transmitted light, there is a problem that measurement is impossible or the measurement accuracy is deteriorated when a nozzle which is opaque or has low transparency is used. It was Further, even if the nozzle itself is transparent, when a colored sample is discharged, there is a problem that the sample adheres to the inner surface of the nozzle even after discharging and the liquid surface cannot be clearly measured.

In addition, in the dispensing device, in order to improve the dispensing accuracy and the reliability of the dispensing, it is desired to detect abnormal suction and liquid leakage. Therefore, in the past, the internal pressure of the piping system connected to the nozzle was monitored, and the suction abnormality and the liquid leakage were determined based on the abnormal fluctuation of the internal pressure. However, these methods do not directly monitor the fluctuation of the liquid level in the nozzle.

It should be noted that Japanese Patent Laid-Open No. 7-146168 and Japanese Patent Laid-Open No. 6-341998 disclose that the liquid level is detected using an ultrasonic wave propagating body equipped with an ultrasonic vibrator. However, neither of them detects the liquid level in the nozzle.

The present invention has been made in view of the above conventional problems, and an object of the present invention is to directly monitor the liquid surface in a nozzle and measure the suction amount and the discharge amount with high accuracy.

Another object of the present invention is to provide a dispensing device capable of determining a suction amount, a discharge amount, a liquid leak, and a suction abnormality by utilizing liquid level detection by ultrasonic waves.

Further, an object of the present invention is to provide a dispensing device which can achieve the focusing of ultrasonic waves for liquid level detection and the blocking of external noise by utilizing a nozzle-like configuration unique to a nozzle. Especially.

A further object of the present invention is to provide a dispensing device capable of detecting the liquid level in the nozzle regardless of whether it is colored or not.

[0011]

In order to achieve the above object, the present invention provides a hollow nozzle for sucking a sample and ultrasonic waves emitted from the base end side of the nozzle to the inner space of the nozzle to generate a reflected wave. It is characterized by including an ultrasonic wave sensor for receiving a wave and an in-nozzle liquid level detecting means for detecting the liquid level of the sample sucked into the nozzle based on a received signal from the ultrasonic sensor.

According to the above construction, the nozzle is provided with the ultrasonic sensor, and the ultrasonic wave is transmitted from the ultrasonic sensor to the internal space of the nozzle. Then, the reflected wave reflected by the liquid surface in the nozzle is received by the ultrasonic sensor. Therefore, if the received signal is monitored, the liquid surface can be identified as an echo having a predetermined level or higher. In this case, the time from the transmission to the occurrence of the liquid level echo correlates with the height of the liquid level of the sample in the nozzle.

The nozzle itself functions as a sound wave path,
The transmitted ultrasonic waves are guided from the nozzle base end side to the tip end side without diverging. The same applies to the reflected wave, and the reflected wave is returned to the inside of the nozzle and is received by the ultrasonic sensor without diverging. Further, the wall surface of the nozzle functions as a shielding member for external noise. Therefore, by transmitting and receiving ultrasonic waves in the nozzle, the S / N ratio can be improved, and highly accurate liquid level detection can be realized.

In a preferred aspect of the present invention, it has a liquid surface height calculating means for calculating the height of the detected liquid surface. That is, the ultrasonic wave propagation distance from the ultrasonic sensor to the liquid surface can be calculated from the time from the transmission to the time when the liquid surface reflected wave is obtained.If the propagation distance is subtracted from the length inside the nozzle, the liquid surface from the tip of the nozzle can be calculated. The height is easily required. Of course, since the reflected wave time until the reflected wave is generated is a function of the height of the liquid surface, the height of the liquid surface can be calculated directly from the reflected wave time by using a table or the like.

In a preferred aspect of the present invention, a suction amount calculation means for calculating the suction amount of the sample sucked into the nozzle based on the detected liquid level is included, and the liquid level at the time of discharging the sample is It includes a discharge amount calculation means for calculating the discharge amount of the sample discharged from the nozzle based on the descending amount. That is, if the form inside the nozzle is known, the liquid amount (suction amount) can be calculated from the height of the liquid surface, and the discharge amount can also be calculated from the descending amount of the liquid surface. In a preferred aspect of the present invention, a liquid leakage determination means for determining a liquid leakage based on the variation of the liquid level in the sample holding state is included. That is, when a leak (air suction) occurs in any part of the piping system or in the fitting portion between the nozzle base and the nozzle tip, liquid leakage occurs, and the liquid level of the sample sucked into the nozzle is gradually lowered. Therefore, the liquid leakage is judged by detecting the temporal fluctuation of the liquid surface.

Further, in a preferred aspect of the present invention, a suction abnormality judging means for judging suction abnormality based on the fluctuation of the liquid surface at the time of sucking the sample is included. Here, the suction abnormality determination means desirably determines the suction abnormality when the liquid surface height is out of the appropriate range with respect to the suction time.

That is, if the nozzle tip opening is clogged or the above-mentioned leak occurs during sample suction, the fluctuation of the liquid level also becomes abnormal. Therefore, in order to improve the reliability of the dispensing, the suction abnormality is determined.

As described above, according to the present invention, liquid level detection by ultrasonic waves can be effectively utilized in a series of dispensing steps of sample suction, sample holding, and sample discharge.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a preferred embodiment of the dispensing apparatus according to the present invention, and FIG. 1 is an overall configuration diagram thereof. In this embodiment, the nozzle 10 that sucks and discharges the sample is composed of a nozzle base 12 made of metal and a nozzle tip 14 formed of a transparent resin or the like. A tip mounting portion 12A having an outer tapered surface is formed at the lower end of the nozzle base portion 12, and the upper end portion 14A of the nozzle tip 14 is detachably fitted into the tip mounting portion 12A. The nozzle tip 14 is used as a so-called disposable, and after dispensing one sample, the nozzle tip 14 is replaced before dispensing the next sample.

The nozzle 10 has a hollow pipe shape as a whole, and has a waveguide structure from another point of view. In the upper end portion 12B of the nozzle base portion 12, a small ultrasonic sensor 18 having an ultrasonic transducer built therein is embedded.
The wave transmission / reception surface of the ultrasonic sensor 18 faces the internal space of the nozzle 10. That is, the wave transmission / reception surface of the ultrasonic sensor 18 faces the inner side of the nozzle tip portion located immediately below it. The tip of the nozzle tip 14 is tapered so that it has a tapered shape, and an opening 14B as a minute hole is formed at the tip thereof. The opening 14B
The diameter of is, for example, 0.5 to 0.7 mm.

A sample 22 to be aspirated is placed in the container 20.
And the container 20 is held vertically by the rack. Note that FIG. 1 shows a state in which a predetermined amount of sample is sucked into the nozzle 10 and the liquid surface thereof is detected by ultrasonic measurement.

The internal space of the nozzle base 12 is branched as shown in FIG. 1, and an air pump 28 is connected to the branch passage 12C via an air tube 26. The air pump 28 functions as a dispensing pump, and specifically includes a syringe 30 and a piston 32.
Depending on the amount of movement of the piston 32 with respect to the syringe 30,
Suction pressure or discharge pressure is generated. The pressure change is transmitted to the inside of the nozzle 10 via the air tube 26,
The sample is sucked and discharged. The pump 28 is mechanically driven by the pump drive mechanism 34. The nozzle 10 is
It is held by a nozzle transport mechanism 36 so that it can be raised and lowered and horizontally moved. Specifically, the nozzle base 12 is held by the nozzle transport mechanism 36.

In FIG. 1, the main control unit 38 is composed of, for example, a computer, and has a dispensing control unit 40 and a nozzle liquid level detection unit (hereinafter, liquid level detection unit) 42.

The dispensing control section 40 performs control for liquid level detection using ultrasonic waves in addition to nozzle elevation control and pump drive control during suction and discharge. When the transmission control unit 40 gives a transmission trigger to the transmission unit 44, the transmission signal is supplied from the transmission unit 44 to the ultrasonic sensor 18, whereby the ultrasonic sensor 18 emits an ultrasonic pulse. The ultrasonic pulse propagates in the inner space (inside air) of the nozzle 10, and the reflected wave reflected by the liquid surface of the sample in the nozzle 10 is received by the ultrasonic sensor 18. The received signal is subjected to processing such as amplification, detection, and noise removal in the receiving unit 46, and then sent to the in-nozzle liquid level detecting unit 42,
Then, the liquid level in the nozzle 10 is detected based on the received signal.

The center frequency of the ultrasonic pulse radiated from the ultrasonic sensor 18 is, for example, in the range of several tens KHz to several Mhz, while considering that the propagation medium is air and the internal form of the nozzle 10. Set to the value. The transmission repetition cycle of the ultrasonic pulse is set to a value larger than the time required for the ultrasonic pulse to reciprocate the distance from the ultrasonic sensor 18 to the nozzle tip. It is desirable that the wave number of waves forming the ultrasonic pulse be appropriately set in consideration of the distance resolution and the signal strength.

In FIG. 1, the dispensing control unit 40 includes a liquid level height calculation unit 50, a suction amount calculation unit 52, a discharge amount calculation unit 54,
It has a liquid leakage determination unit 56 and a suction abnormality determination unit 58. Each configuration will be described in detail below.

The liquid level calculation unit 50 calculates the height of the liquid level based on the liquid level detected by the in-nozzle liquid level detection unit 42. In FIG. 2, the received signal is schematically illustrated as a waveform. As shown in FIG. 2A, the received signal includes a liquid surface echo 10 at a position corresponding to the liquid surface.
2 has occurred. Therefore, if the liquid level echo 102 is discriminated by the predetermined threshold value 100, the time t1 from the time of transmission to the time of generation of the liquid level echo can be obtained.
Then, by multiplying t1 by the velocity of the ultrasonic wave in the air, the distance h1 from the ultrasonic sensor 18 to the liquid surface in FIG. 3 can be calculated. Since the length of the nozzle tip 14 is known and therefore the distance h0 from the ultrasonic sensor 18 to the tip of the nozzle tip 14 is also known, the desired liquid level height h2 can be obtained by subtracting h1 from h0.
Can be calculated easily. The in-nozzle liquid level detection unit 42 shown in FIG. 1 discriminates the liquid level echo 102 based on the threshold value 100 as shown in FIG.
Is being measured. Then, the liquid level calculation unit 50
As described above, the liquid level height h2 is calculated from the time t1.

When the liquid level height h2 is obtained in this way, the suction amount calculation unit 52 calculates the liquid amount of the sample 22 sucked into the nozzle 10. That is, since the internal form of the nozzle tip 14 is known, the suction amount can be calculated from the height h2 of the liquid surface. In this case, for example, a table for directly obtaining h2 and the suction amount from t1 may be used. Further, such a table may be switched and used depending on the type of the nozzle tip 14.

The discharge amount calculation unit 54 shown in FIG. 1 calculates the discharge amount from the amount of lowering of the liquid surface. As shown in FIG. 2B, the liquid surface echo 104 first occurs at the time t1, and the liquid surface echo 106 after the sample discharge is at the time t.
In the case of 2), since the liquid amount can be calculated as described above at each time, the discharge amount U can be obtained from the difference in the liquid amount at each time as shown in FIG. When the inner diameter of the nozzle tip 14 is constant from t1 to t2, the discharge amount U may be directly obtained from the time difference t3 between t1 and t2 as shown in FIG. 2 (B).

The liquid leakage determination unit 56 shown in FIG. 1 determines the liquid leakage due to the leakage generated in the piping system or the like by monitoring the amount of the liquid in the nozzle in the sample holding state in which neither suction nor discharge is performed. To do. Specifically, as shown in FIG. 5, when the liquid level fluctuation ΔU occurs in the pump stopped state, it is determined that liquid leakage has occurred.

To monitor such liquid leakage, for example, the liquid amount immediately after sample suction is stored, the liquid amount is measured again immediately before ejection, and an alarm is generated if there is a difference in liquid amount. You may let me. Alternatively, the liquid surface fluctuation can be confirmed by comparing the time until the liquid surface echo is generated, instead of comparing the liquid surfaces.

Next, the suction abnormality determination unit 58 shown in FIG. 1 will be described. The suction abnormality determination unit 58 monitors a temporal change in the liquid surface height during suction and determines a suction abnormality. FIG. 7A shows a graph 200 as a liquid level height variation when normal suction is performed. In the present embodiment, as shown in FIG. 7B, the suction abnormality determination unit 58 sets the determination curves 202U and 202L on the upper and lower sides of the normal graph 200 at regular intervals, and the actual determination is made. The graph 204 of the liquid level is such 2
The suction abnormality is determined when the area is outside the area surrounded by the two determination curves. FIG. 7B shows a state in which a leak occurs in the piping system and the like, whereby the sample cannot be sucked with a sufficient suction pressure. As shown in the figure, the gradient of the graph 204 showing the liquid level is smaller than that of the normal one.

On the other hand, FIG. 7C shows a graph 206 in the case where a clog has occurred. That is, as shown in FIG. 6, when the tip opening of the nozzle tip 14 is blocked by the foreign matter 200 floating in the sample 22, the liquid level of the sample does not rise even if suction pressure is generated by the pump. The state is shown in FIG. 7C, that is, the graph 206 is deviated from the area surrounded by the curves 202U and 202L from the time when the occurrence of the occurrence. Therefore, the suction abnormality determination unit 58 generates an alarm indicating suction abnormality based on the pop-out of the graph from such a determination area.

The curves 202U and 20 shown in FIG.
It is desirable to appropriately set the determination area surrounded by 2L in consideration of required accuracy of suction abnormality determination and elimination of erroneous determination. For example, it is possible to increase the width of the determination area as the time elapses.

Next, the operation of the dispensing apparatus of this embodiment will be described with reference to FIG.

First, in a state where the nozzle 10 is positioned above the container 20 containing the sample 22, the nozzle 10 is pulled down by the nozzle transport mechanism 36 in S101, and the nozzle 10 is moved to the liquid surface at the tip of the nozzle in S102. The sample is aspirated while the insertion amount of is maintained constant.

In S103, the liquid level is detected based on the transmission and reception of ultrasonic waves by the ultrasonic sensor 18 as described above. In this case, the suction amount calculation unit 52 calculates the suction amount, that is, the suction amount is constantly monitored. At the same time, the suction abnormality determination unit 58 constantly monitors the suction abnormality.
If a leak or blockage like the one shown in is generated, S
An alarm occurs at 107.

In S104, it is determined whether or not the monitored suction amount has reached the set value, and if the suction amount has reached the set value, suction is stopped in S105,
Further, in S106, the nozzle 10 is moved to the nozzle transport mechanism 3
It is pulled upward by 6. Then, in S108, the nozzles are transported in the horizontal direction as needed. The liquid leakage determination unit 56 functions during such a nozzle rise or nozzle movement, and in the example shown in FIG. 8, fluctuations in the liquid level are constantly monitored.
At 107, a liquid leak alarm is generated. of course,
Liquid leakage may be determined by comparing the liquid amount immediately after suction and the liquid amount immediately before discharge.

In S109, the nozzle transport mechanism 36 pulls the nozzle 10 downward toward the container for discharging, and in S110, discharging is started. And S11
In 2, the ultrasonic wave is again transmitted and received by the ultrasonic sensor 18, and the fluctuation of the height of the liquid surface is monitored. In this case, the discharge amount calculation unit 54 calculates the discharge amount. In S113,
It is determined whether or not the calculated discharge amount has reached the set value, and when the discharge amount has reached the set amount, the discharge is stopped in S114, and thereafter, S11.
At 5, the nozzle 10 is pulled upward by the nozzle transport mechanism 36. In S116, it is determined whether or not to continue discharging the sample into the next container, and if it is to continue, the steps from S108 are repeatedly executed.

According to the above embodiment, by providing the ultrasonic sensor 18 in the nozzle 10, various calculations and determinations can be realized, and highly accurate dispensing can be achieved.

[0042]

As described above, according to the present invention,
The liquid surface in the nozzle can be directly monitored, and the suction amount and the discharge amount can be calculated with high accuracy. Further, according to the present invention, it is possible to determine liquid leakage and suction abnormality in addition to the suction amount and the discharge amount by utilizing the liquid level detection by ultrasonic waves. Furthermore, according to the present invention, it is possible to simultaneously realize the focusing of ultrasonic waves for detecting the liquid level and the blocking of external noise by utilizing the unique form of the nozzle. Further, according to the present invention, there is an advantage that the liquid level can be detected even for a colored nozzle.

[Brief description of drawings]

FIG. 1 is a diagram showing an overall configuration of a dispensing device according to the present invention.

FIG. 2 is a waveform diagram showing a waveform of a received signal.

FIG. 3 is a diagram showing a calculation principle of a liquid amount.

FIG. 4 is a diagram showing a calculation principle of a discharge amount.

FIG. 5 is a diagram showing fluctuations in the liquid surface when liquid leakage occurs.

FIG. 6 is a diagram showing a state in which a nozzle tip opening is clogged with foreign matter.

FIG. 7 is a diagram showing a determination range for a suction abnormality determination.

FIG. 8 is a flowchart showing the operation of the dispensing device according to the present invention.

[Explanation of symbols]

10 nozzles, 12 nozzle bases, 14 nozzle tips, 18 ultrasonic sensors 22, samples, 28 pumps, 34 pump drive mechanism, 3
6 Nozzle transport mechanism, 38 Main control unit, 40 Dispensing control unit, 42 Nozzle liquid level detection unit, 50 Liquid level height calculation unit, 52 Suction amount calculation unit, 54 Discharge amount calculation unit, 56
Liquid leakage determination unit, 58 suction abnormality determination unit.

Claims (7)

[Claims] 1. A hollow nozzle for sucking a sample, an ultrasonic sensor for radiating ultrasonic waves from the base end side of the nozzle to the internal space of the nozzle, and receiving a reflected wave, and a received signal from the ultrasonic sensor. And a liquid level detecting means in the nozzle for detecting the liquid level of the sample sucked into the nozzle based on the above. 2. The dispensing apparatus according to claim 1, further comprising liquid level height calculating means for calculating the detected height of the liquid level. 3. The dispensing apparatus according to claim 1, further comprising suction amount calculation means for calculating a suction amount of the sample sucked into the nozzle based on the detected liquid level. . 4. The apparatus according to claim 1, further comprising a discharge amount calculation means for calculating a discharge amount of the sample discharged from the nozzle based on a descending amount of the liquid surface at the time of discharging the sample. Note device. 5. The dispensing apparatus according to claim 1, further comprising a liquid leakage determination unit that determines a liquid leakage based on a change in liquid level in a sample holding state. 6. The dispensing apparatus according to claim 1, further comprising suction abnormality determination means for determining suction abnormality based on a change in liquid level during sample suction. 7. The dispensing apparatus according to claim 6, wherein the suction abnormality determination means determines a suction abnormality when the liquid level is out of an appropriate range with respect to the suction time.