JP3907819B2 - Liquid level detector - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for detecting the liquid level of a liquid in a container using a probe or the like. For example, the present invention relates to a liquid level detection method assuming an automatic analyzer that performs a suction process after detecting the liquid level.
[0002]
[Prior art]
In recent years, various analyzers including the medical field have been proposed. In particular, as the processing speed of the analyzer itself increases, the moving speed of the probe (electrode) used for detection is also required to be higher. Therefore, if the detection judgment is delayed for a certain period of time in order to prevent false detection in the descending operation for detecting the liquid level of the sample (sample), sending a stop signal to the sampling probe driving means will be delayed. The depth at which the probe enters the sample increases. In particular, when the amount of the sample is very small, the probe tip may come into contact with the bottom surface of the container. Further, even when the sample is sufficient in the container, the probe is inserted deeper than necessary, and the influence of contamination between different samples also increases.
As described above, the following techniques have also been proposed in the technology related to the stop operation of the probe, the dispensing nozzle, and the like. Generally, in a liquid level detection device that detects a liquid level using an oscillator, an electrode connected to the oscillator, and a probe that receives a signal induced by the electrode, the probe is stopped when the liquid level is detected. There was already a liquid level detection technology to be used.
[0003]
Also, in recent Japanese Patent Application Laid-Open No. 8-210896, after detecting the liquid level by the liquid level detection device and stopping the probe, the liquid level in the probe is detected based on the output of the liquid level detection device during the liquid suction operation. There is also a proposal of an automatic chemical analyzer that monitors the suction state and judges the quality.
Further, JP-A-8-114604 has a determination means for determining whether or not the probe has continued to contact the liquid surface until the probe detects the liquid level and completes the suction. There is also a proposal of an automatic analyzer that notifies the operator of this situation when it is determined that contact is not continuously detected.
[0004]
[Problems to be solved by the invention]
However, each of the above conventional techniques has problems that must be solved. For example, even if bubbles are adhering to the surface of a sample such as blood, or if the liquid level is erroneously detected due to the effects of external noise, etc., the tip of the probe is attached to the sample because the liquid level is detected and the suction operation is performed. The sample is not sufficiently submerged and the sample is sucked. In such a case, when the sample is on the rack, other analysis operations are performed as usual, and the rack moves, so that it takes time to re-dispense the sample. It was.
One reason for this is that the time from when the liquid level detection sensor detects a contact signal due to bubbles, external noise, or static electricity to when the separation signal is detected is much shorter than when the probe touches the liquid level. Since this is a signal, when a signal of a predetermined time or longer is input, it is generally determined that it is a liquid level detection signal and a stop signal is sent to the driving means to stop the descent of the probe.
[0005]
In addition, as a problem of JP-A-8-210896 and JP-A-8-114604, even if it is determined that the suction is empty during the suction, or the probe is separated from the liquid surface during the suction, The sample aspirated partway is wasted, and if the reagent is dispensed first, the reagent is also wasted. And since the dispensing is not performed in the cycle, the analysis is not performed. Subsequent processing methods are either to dispense again in the next cycle or just inform the operator that aspiration has not been performed correctly. Therefore, if such re-dispensing and notification to the operator are repeated, it takes a long time to analyze all samples. In addition, it is conceivable that, after determining the idle suction, it is possible to descend again and perform the suction again. However, in this case, there is a problem that it takes an extra time to reset the suction operation.
[0006]
Therefore, an object of the present invention is to prevent the probe from descending from the upper point without affecting the analysis sequence even when the liquid level detection device erroneously detects the liquid level due to bubbles, external noise or static electricity. It is an object of the present invention to provide a liquid level detection device capable of performing a series of operations for performing injection and the like within a predetermined time in one cycle of the analysis.
[0007]
[Means for Solving the Problems]
To achieve the above object, a first aspect of the present invention Liquid level detection device Includes a liquid transfer means for sucking the liquid or adding a desired liquid to a storage container for containing the predetermined liquid, and a predetermined contact signal indicating that the tip of the liquid transfer means is in contact with the surface of the liquid. And a detection means for detecting separation from the liquid by a predetermined detachment signal, and a tip of the liquid transfer means is lowered into the container, and after the contact signal is detected, the tip is discharged from the tip. Determining means for determining whether or not the separation signal is detected before transferring the liquid. After the contact signal is detected by the detection means, the liquid transfer means is detected by a predetermined driving means. The separation signal is detected before shifting to the liquid transfer operation. In addition, when the time from when the contact signal is detected by the detection unit to when the separation signal is detected is shorter than the time required for the liquid transfer unit to stop, the determination unit detects the contact signal. The determined position is not a true liquid level .
[0008]
The second aspect of the present invention Liquid level detection device Is Of the present invention First aspect Liquid level detection device In this case, even if the liquid transfer means erroneously detects the liquid level, the liquid transfer means descends from a preset upper point to detect the correct liquid level, and then analyzes a series of operations up to the liquid transfer operation. Control is performed within a predetermined time in one cycle.
[0009]
[Action]
In the liquid level detection system according to the aspect of the claims of the present invention, the following actions are produced by the above means. That is, in this liquid level detection method, even if the liquid level detection device misdetects the liquid level due to external noise, static electricity, bubbles, etc., the probe descends from the upper point without affecting the analysis sequence, and the correct liquid level is detected. Is detected. Then, a series of operations for performing subsequent dispensing and the like can be continuously and automatically performed within a predetermined time in one cycle of analysis.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the liquid level detection device of the present invention will be described in detail with reference to a plurality of embodiment examples and modifications thereof.
(First embodiment)
FIG. 1 shows the configuration of a liquid level detection device as a first embodiment of the present invention and a second embodiment described later, and FIGS. 2 (a) and 2 (b) show this liquid level detection device. 2 shows an enlarged positional relationship between the tip position of the probe and the liquid in the container.
[0011]
A liquid level detection apparatus 10 according to an embodiment of the present invention is configured as shown in FIG. That is, a metal probe 1 attached to a dispensing nozzle or the like that can be accessed (inserted / removed) into, for example, a liquid storage container 4 such as a test tube that stores a liquid 20 to be detected, and the probe 1 As shown in the figure, the arm 2 is held in the vertical direction, the driving means 3 for moving the arm 2 in the vertical direction by moving up and down and moving in the horizontal direction (x direction) by rotation, and the electricity obtained through the probe 1. A sensor 7 that detects a change in the state and generates a predetermined signal; a liquid level detection circuit 5 that receives a signal from the sensor 7 to detect the level of the liquid; The liquid level detection device 10 is composed of a determination unit 6 that determines whether the liquid level is true based on the received signal.
[0012]
When the tip of the probe 1 touches some liquid, the sensor 7 sends an analog electric signal to the liquid level detection circuit 5, and this signal is recognized as a “contact signal”. When the tip of the probe 1 moves away from the touched object, an analog signal recognized as a “detachment signal” is sent to the liquid level detection circuit 5. The liquid level detection circuit 5 converts each sent signal into a digital signal and supplies it to the determination means 6. On the other hand, the drive unit 3 connected to the determination unit 6 is driven by a command from the determination unit 6, but the determination unit 6 always recognizes the drive state.
[0013]
In this way, the probe 1 is lowered straight toward the center of the upper opening of the container 4 in which the sample and reagent liquid 20 is accommodated, and further penetrated into the container 4. When the tip of the probe 1 comes into contact, the liquid level detection circuit 5 detects a contact signal, immediately sends a signal to the drive means 3, and lowers the probe 1 into the container 4 to a predetermined depth and stops it. Then, after a predetermined suction operation by a predetermined dispensing means (not shown), the probe 1 is raised by the driving means 3 and when the probe tip is separated from the liquid surface, the detection circuit 5 detects a separation signal.
At this time, since it is necessary to perform the sample dispensing operation more quickly with the recent increase in the speed of the analysis apparatus, the probe 1 is lowered at a high speed into the container 4 containing the liquid 20 by the driving means 3.
[0014]
In order to achieve the above object, in the present invention, the determination means 6 recognizes the contact signal generated by the sensor 7 for detecting the liquid level, and even if the probe 1 is stopped or stopped by the drive means 3. Before the probe 1 performs the next suction operation, it is determined whether or not a separation signal is issued by the sensor 7. When the determination means 6 detects that the separation signal is detected and the probe 1 is not in contact with the liquid level, the driving means 3 re-drives the probe 1 to detect the true liquid level. To control.
[0015]
In general, as shown in FIG. 2 (a), bubbles or bubbles 21 may be formed on the surface of a liquid containing proteins such as blood after processing such as centrifugation, stirring, and dispensing. Even when the liquid level detection circuit 5 detects a contact signal as if the probe 1 is in contact with the liquid level, it is possible to prevent the probe 1 from entering the sample more than necessary. Therefore, it is necessary to send a stop signal to the driving means 3 at the same time when the contact signal is detected.
[0016]
For example, when the probe 1 contacts the bubble 21 and the contact signal is detected by the liquid level detection circuit 5, the detection circuit 5 sends a stop signal to the driving means 3, and the probe 1 starts a stop operation. However, since the probe 1 contacts the bubble 21, the detection circuit 5 detects the contact signal. Immediately thereafter, the detection circuit 5 detects the separation signal immediately after the bubble is broken and disappears. Here, even if the bubbles do not disappear due to high viscosity, the probe 1 similarly detects a separation signal when the bubbles penetrate the bubbles.
At this time, when the time from when the contact signal is detected by the liquid level detection circuit 5 to when the separation signal is detected is shorter than the time t required for the probe 1 to stop, the determination means 6 determines this position. It is determined that the liquid level is not reached.
[0017]
The operation up to this point will be described based on the positional relationship between the tip position of the probe 1 and the container 4 shown in FIG. 2A. For example, several bubbles 21 generated on the surface of blood or the like in the container 4 are It exists at the height of the position d1 by arbitrarily dispersing and overlapping on the liquid level position (d3). When the probe 1 moves downward in the direction of the broken line arrow in FIG. 2A and the probe tip touches the bubble 21 at this position d1, there is a case where this is erroneously detected as a liquid level. In that case, the descent continues further as judged by the judging means, and continues the descent operation after passing through the position d2 to the position d3 on the lower liquid level as shown in FIG. 2 (b). If this position is determined to be the true liquid level, the vehicle descends and stops while decelerating to a position d4 where the illustrated penetration depth is set to the stop position.
[0018]
Here, FIG. 3 is a graph showing changes in the pulse rate of the pulse signal accompanying the descending operation of the probe 1 of the liquid level detection device at that time. This pulse signal is generated by using, for example, a timing belt in a mechanism constituting the driving means. The pulse rate is proportional to the driving speed. It is possible to monitor and control by counting the number of pulses. According to this graph, the probe stopped at the upper point increases the descending speed, reaches a constant descending speed at t1, and thereafter continues to descend toward the liquid surface at a constant speed. The probe contacts a certain liquid at t2 and generates a contact signal (however, a false detection signal). When the determining means immediately instructs the driving means to stop the lowering operation of the nozzle, deceleration starts. During this time, the determining means determines whether or not this is the true liquid level position, and determines that it is a false detection at t3. The descent speed at that time is maintained and further descent operation is continued. When the contact signal is detected again at t4 and it is determined that this is the true liquid level position, the vehicle is stopped at t5 while gradually decelerating so that the depth of penetration below the liquid level becomes constant. At this time, the determination means 6 calculates the stop time from the pulse rate at the time of lowering again and issues a stop signal to the drive means 3 at an appropriate timing, thereby controlling the depth at which the probe 1 enters the sample to be constant.
[0019]
Further, when the probe 1 comes into contact with a bubble or the like, the time from when the contact signal is once detected until the next separation signal is detected is extremely short. This time is sufficiently shorter than the stop time t from when the vehicle will decelerate to when it will stop. Therefore, the determination means 6 can determine that this position is not the liquid level before the probe 1 performs a desired suction operation. Then, a drive signal is immediately sent to the drive means 3, and the probe 1 is further lowered at a constant speed or reaccelerated. After that, the liquid level is detected again, and if the true liquid level can be determined in the same way, the dispensing nozzle is submerged to an appropriate depth at which no empty suction occurs, and preferably stopped after t4. From t5 onward, a desired dispensing operation for analysis is performed. Regardless of whether or not there is a false detection, the probe is continuously and automatically performed within a predetermined time determined by one cycle of a series of analyzes until the probe descends from the initial upper point position and ends the dispensing operation. Control.
[0020]
(Operation effect 1)
As described above, in the first embodiment, even when the liquid level detection circuit detects a contact signal as if the probe is in contact with the liquid level due to bubbles or bubbles in the container, this probe is used. The depth of penetration into the sample can be made sufficiently large, and it is prevented from becoming larger than necessary. The determination means calculates the stop time from the pulse rate at the time of lowering again, and issues a stop signal to the drive means, thereby making the depth of penetration of the probe 1 into the sample constant.
Furthermore, since a stop signal is sent to the driving means 3 at the same time as the contact signal is detected, the tip of the dispensing nozzle or the like is brought into the correct depth, so that it is possible to prevent idle suction or the like in the suction operation.
[0021]
(Modification 1)
The form of the liquid level detection apparatus exemplified in the first embodiment can be variously modified similarly to the second and third embodiments described later. For example, the liquid level detection device 10 may also serve as a device having a dispensing function for dispensing a certain liquid from a container to a container or an analysis function for performing a predetermined analysis. It may be a system device capable of continuously performing stirring, dispensing, analysis, cleaning, and the like following the surface detection operation.
[0022]
The type of sensor for detecting the liquid level is not limited. For example, a pressure sensor that detects a pressure change in a pipe, a sensor that detects an air flow (air) generated in the pipe, a sensor that detects a capacitance, etc. The installation location of the sensor may be changed to an appropriate position.
Further, the probe and the dispensing nozzle tip may be disposable to prevent sample contamination as much as possible.
[0023]
(Second Embodiment)
As described above, the liquid level detection device according to the second embodiment is almost the same as the device according to the first embodiment, so that the description of the structure is omitted. However, a dedicated timer for measuring time is provided. It is structurally different.
FIG. 4 is a graph showing changes in the pulse rate of the pulse signal accompanying the descent operation of the probe of the liquid level detection device according to the second embodiment of the present invention.
[0024]
The descending operation and detection timing in this example are set differently from those in the first embodiment. That is, in this example, the determination condition regarding the true liquid level position which is determined by the determination unit 6 is defined as follows. The time required from when the probe 1 comes into contact with the sample and the liquid level detection circuit 5 detects the contact signal to when the probe 1 is separated from the sample and the separation signal is detected is counted by a timer (not shown). This timed time is compared to a predetermined time that does not affect the sequence of analysis.
The “predetermined time” is a value set within a time period from the start of the descent from the upper point of the probe 1 to the start of the suction operation defined by one cycle of analysis.
[0025]
Referring to FIG. 4 showing the change of the pulse rate according to the second embodiment, it is clear that this example also operates to recognize the false detection and immediately detect the true liquid level. In addition, immediately after the erroneous detection, the descending speed is once set to zero and the probe is stopped. Specifically, the process from t1 through t1 to t2 is the same operation as in the first embodiment described above. When the probe comes into contact with some liquid at t2 and generates a contact signal (however, an erroneous detection signal), the determination means immediately instructs the drive means to stop the advancing operation of the probe so as to suddenly stop, and simultaneously determines the determination. The means determines whether or not this is the true liquid level position. When the descent speed becomes zero and it can be judged that it is a false detection at t3, the descent speed is immediately increased from zero and further lowered. Resume operation. When the contact signal is detected again at t4 and it is determined that this is the true liquid level position, a constant low speed is maintained until the submerged depth reaches a predetermined depth, and then the vehicle is decelerated and stopped at t5. At this time, the determination means 6 calculates the stop time from the pulse rate at the time of lowering again, and issues a stop signal to the drive means 3 at an appropriate timing, thereby setting the depth at which the probe 1 enters the sample to a predetermined position. Control. In this example, the probe 1 is completely stopped once due to the occurrence of erroneous detection. After that, before starting the suction operation, the descending operation is performed again to detect the true liquid level.
[0026]
(Operation effect 2)
As described above, according to the second embodiment, the probe 1 comes into contact with the sample, the liquid level detection circuit 5 detects the contact signal, and the probe 1 leaves the sample until the separation signal is detected. The required time is measured by a timer or the like, and the measured time is controlled by comparing with a predetermined time that does not affect a series of analysis sequences. Therefore, even if the probe 1 is stopped once due to erroneous detection, the probe 1 can be lowered again before the suction is started to detect the liquid level.
Further, by calculating the stop time from the pulse rate at the time of lowering again, a stop command can be issued to the driving means 3 at an appropriate timing, so that the probe 1 can be embedded in the sample at a certain depth, As a result, it is possible to prevent idle suction and the like in the suction operation.
[0027]
(Third embodiment)
The liquid level detection device according to the third embodiment has a configuration in which the sensor 7 according to the above-described embodiment has an oscillation circuit and detects the liquid level with a signal when the capacitance changes. Since the configuration is the same as that of the apparatus, description thereof is omitted. However, the oscillation circuit may be arranged not on the probe side but on the container side as in a known electrostatic liquid level detection mechanism.
The feature of the liquid level detection device of this example is that even when static electricity generated in the container is detected, this detection is not erroneously determined as liquid level detection, and the true liquid level is lowered by further lowering the probe tip. A series of liquid level detection methods to detect are provided.
[0028]
FIG. 5 illustrates the positional relationship between the charged container and the probe according to the third embodiment of the present invention. Specifically, FIG. 5 (a) shows the position of the probe tip when erroneous detection is caused by the influence of static electricity or the like, and FIG. 5 (b) shows the case where the liquid level detection position is reached later.
When the electrostatic charge container 4 is used to detect the liquid level of the liquid contained in the container 4 and descends in the direction of the broken arrow, the probe 1 is slightly below the upper end near the center of the opening of the container 4 (d1 Immediately after the false detection signal is issued when the vehicle descends, the electrostatic charge that has been charged is instantaneously discharged and removed, whereby a separation signal is obtained. Although this time is extremely short, erroneous detection is similarly determined by the method described above.
[0029]
When a relatively long container such as a test tube is used as the container, the distance between the false detection positions d1 and d2 is close, while the distance between d2 and d3 is quite far away. There are many. Therefore, it is desirable that the descending speed during this period be controlled at a high speed. On the other hand, it is desirable to perform control so that the high-speed descending operation is suddenly decelerated or braked from the liquid level d3 and stopped at a position d4 corresponding to a predetermined depth of penetration.
[0030]
(Operation effect 3)
As described above, even when the liquid level detection circuit 5 detects a contact signal as if the probe 1 is in contact with the liquid level due to extraneous noise or static electricity of the container 4, the sample of the probe 1 is used. A stop signal is sent to the driving means 3 at the same time as the contact signal is detected in order to prevent the depth of penetration into the unnecessarily large. And since the tip of the nozzle is submerged to the correct depth, it is possible to prevent empty suction.
Further, according to the third embodiment in which such movement is performed, even if the position of the liquid level is erroneously detected due to the operation environment, the container 4 to be used, etc., this is accurately recognized and immediately retried. To detect the true liquid level accurately.
[0031]
It should be noted that malfunction of the liquid level detection circuit 5 and the like due to external noise may be prevented by the conventional shield technology, etc., but in the present invention, even if the liquid level is erroneously detected as a malfunction due to such noise, It can be automatically executed in a series of sequences until the true liquid level is correctly detected.
Therefore, the liquid level detection device as in this example is particularly suitable for use in an environment where external noise is likely to occur or when a liquid or container where static electricity is likely to be generated is used.
[0032]
According to the plurality of embodiments described above, the following operational advantages can also be obtained.
(A) Even if the probe detects a liquid level incorrectly, a series of operations in which the probe descends from the upper point and performs dispensing operations can be performed within a predetermined time of one cycle of analysis, improving efficiency. Contribute to.
(B) Even if the probe is operated at high speed, the amount of protrusion below the liquid level is not increased, and countermeasures against bubbles, static electricity, noise, etc. can be taken.
(C) As a result, the contamination of the specimen can be minimized.
(D) Moreover, the reagent to be used and especially a sample are not wasted.
[0033]
(Other variations)
In addition to the above-described embodiments, the present invention can be variously modified without departing from the gist of the present invention. For example, the shape and function of each part of the apparatus related to the exemplified liquid level detection method can be variously changed as necessary, and can be appropriately combined with others. It can be applied to contact-type liquid level detection methods (for example, air, ultrasonic vibration, etc.) other than electrical detection, and can also be applied to an apparatus that dispenses while replacing an insulating disposable tip at the probe tip. Also, a liquid level detection rod separate from the probe may be employed for both air bubbles and static electricity.
[0034]
In addition, with regard to the configuration in which bubbles or static electricity disappears by contact with the probe, if the contact signal is obtained again after returning the probe to the liquid level detection position, bubbles, static electricity, etc. It is preferable in that accurate liquid level detection can be performed even when the liquid level is extremely close to the liquid level.
Also, if the probe has a configuration that can discharge air, return to the liquid level detection height immediately after the detection signal, taking into account the minute case that bubbles do not disappear even if the probe contacts. Therefore, it may be possible to efficiently obtain only the true liquid level detection signal by discharging air and pushing the microbubbles away by the wind pressure. In this case, if the liquid level is detected by changing the discharge pressure of air, it is not necessary to raise the probe tip to the liquid level detection height again.
[0035]
Further, the combination of the liquid level detection device according to the present invention and the technology in other fields, the liquid to be used and the container for storing the liquid are not limited to the exemplified reagents and test tubes, but various liquids, microplates, cuvettes, petri dishes. Any desired one can be used. In addition to the case of sucking a liquid, the present invention can be applied to a case where a reagent (or sample) or the like is added to a reaction container in which a sample (or reagent) or the like is already contained by dispensing or the like. Is also applicable.
[0036]
Although the present invention has been described based on the embodiments and modifications, the present invention includes the following inventions.
[1] A predetermined contact signal indicating that a suction means for sucking the liquid or adding a desired liquid to a storage container for storing the predetermined liquid, and that the tip of the liquid transfer means has contacted the surface of the liquid Detecting means for detecting that the liquid is separated from the liquid by a predetermined detachment signal; and lowering the tip of the liquid transfer means into the container and recognizing the contact signal; Determination means for determining whether or not the separation signal is detected before liquid is transferred,
When the detection means detects the contact signal, and when the determination means determines that the separation signal is detected before the liquid transfer means is shifted to a liquid transfer operation by a predetermined drive means, Provided is a liquid level detecting device characterized in that the liquid transfer means is lowered again by a driving means to detect a true liquid level.
[0037]
[2] Even when the liquid transfer means erroneously detects the liquid level, the liquid transfer means descends from a preset upper point, detects a correct liquid level, and then performs a series of operations up to the dispensing operation. The liquid level detection apparatus according to [1], wherein control is performed so that the analysis is performed within a predetermined time in one cycle of analysis.
[3] The determination unit detects the contact signal when the time from when the contact signal is detected by the detection unit to when the separation signal is detected is shorter than the time required for the liquid transfer unit to stop. The liquid level detection device according to [1], wherein the determined position is determined not to be a true liquid level.
[0038]
In addition, the following inventions are also included.
[A] a sampling probe for sensing contact with a sample or reagent in a predetermined container and transferring or discharging liquid;
Driving means for driving the probe to move it to a desired position;
A liquid level detection sensor for detecting by a contact signal indicating that the probe has come into contact with the sample or reagent, and for detecting by a separation signal indicating that the probe has been separated from the sample or reagent;
Determining means for lowering the probe into the container, detecting the contact signal, and determining whether the separation signal is detected before the probe sucks the sample or reagent;
Comprising
Even if the liquid level detection sensor detects a contact signal and the probe is stopped or braked by the driving means, the separation level signal is detected by the liquid level detection sensor before the probe is aspirated. A liquid level detection method for an automatic analyzer, wherein when the determination is made, the probe is re-driven by the drive and the true liquid level is detected.
[0039]
[B] A time measuring means for time measurement is further provided,
The time measured by the time measuring means after the probe is in contact with the sample or the reagent and the liquid level detecting means detects the contact signal until the probe is separated from the sample or the reagent and the separation signal is detected. In addition, the liquid level detection method according to [A], wherein the measured time is compared with a predetermined time that does not affect a series of analysis sequences.
[C] The determination condition regarding the true liquid level position which is used as a reference by the determination unit is as follows:
In the case where the time from when the contact signal is detected by the detection means until the separation signal is detected is shorter than the time required for the probe to stop, the position where the contact signal is detected is the true liquid level. The liquid level detection method according to [A], characterized in that it is not determined.
[0040]
[D] Even if the probe erroneously detects the liquid level, a series of analysis operations until the probe descends from a preset upper point and performs a desired dispensing operation is performed in one cycle of this analysis. The liquid level detection method according to [A], wherein control is performed so as to be performed within a predetermined time.
[E] The determination means calculates the stop time of the probe from the rate of the pulse signal generated by the drive means at the time of lowering again, and issues a stop signal to the drive means, whereby the probe is sent to the sample or reagent. The liquid level detection method according to [A], wherein the depth of penetration is controlled to be constant.
[0041]
【The invention's effect】
As described above, according to the liquid level detection device of the present invention, as described based on a plurality of embodiment examples and modifications, even if the liquid level is erroneously detected due to external noise, static electricity, bubbles, etc., the erroneous analysis procedure is used. It is possible to provide a liquid level detection method in which a series of dispensing operations can be performed within one cycle of analysis without being affected.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing a configuration of a liquid level detection device as an embodiment of the present invention.
FIG. 2 shows the positional relationship between the liquid container and the probe according to the first embodiment of the present invention,
(a) is an explanatory view showing the case where the probe tip is in contact with bubbles generated on the liquid surface,
(b) is explanatory drawing which shows the case where it reaches | attains the detection position of a liquid level further through this bubble.
FIG. 3 is a graph showing a change in a pulse signal generated by a sensor when the probe of the liquid level detection device according to the first embodiment is used for liquid level detection.
FIG. 4 is a graph showing a change in a pulse signal generated by a sensor that is erroneously detected when the probe of the liquid level detection device according to the second embodiment of the present invention is used for liquid level detection.
FIG. 5 shows the positional relationship between the liquid container and the probe according to the second embodiment,
(a) is an explanatory view showing the position of the probe tip when erroneously detecting due to the influence of static electricity or the like,
(b) is explanatory drawing which shows the case where it reaches | attains the detection position of a liquid level further after that.
[Explanation of symbols]
1 ... probe (means also serving as a suction means such as a dispensing nozzle),
2 ... arm,
3 ... Driving means,
4 ... Liquid container,
5 ... Liquid level detection circuit (liquid level detection means),
6: Determination means,
7: Sensor (means included in the liquid level detection means),
10 ... Liquid level detection device (device also serving as an analysis device),
20 ... Liquid (sample, reagent, etc.),
21 ... Bubbles, bubbles.

Claims (2)

A liquid transfer means for sucking the liquid or adding a desired liquid to a storage container for storing a predetermined liquid;
Detecting means for detecting that the tip of the liquid transfer means is in contact with the surface of the liquid by a predetermined contact signal, and detecting by means of a predetermined separation signal that the tip of the liquid transfer means is separated from the liquid;
Determining means for lowering the tip of the liquid transfer means into the container and determining whether the separation signal is detected before the liquid is transferred from the tip after the contact signal is detected; Comprising
After the contact signal is detected by the detection means, the separation signal is detected by the predetermined drive means before the liquid transfer means shifts to the liquid transfer operation , and the contact signal is detected by the detection means. When the time until the separation signal is detected is shorter than the time required for the liquid transfer means to stop, the determination means determines that the position where the contact signal is detected is not a true liquid level. A liquid level detection device characterized by   Even when the liquid transfer means erroneously detects the liquid level, a series of operations up to the liquid transfer operation after the liquid transfer means descends from the preset upper point and detects the correct liquid level is analyzed. The liquid level detection device according to claim 1, wherein the liquid level detection device is controlled so as to be performed within a predetermined time in the cycle.

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