JP2022015690A - Liquid level position sensor, liquid level position detection method, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid level position sensor or the like capable of appropriately detecting a liquid level position. A liquid level position sensor 100 is a liquid level position sensor 100 that detects the liquid level position of a liquid 104 housed in a container 102 having a wall portion 103, and the positions in the vertical direction are different from each other, and the wall portion. Calculation to detect the liquid level position based on the difference between the measurement unit 90 that measures the capacitance between the reference electrode 107 and the plurality of measurement positions along the 103 and the capacitance at the plurality of measurement positions. A unit 80 is provided. [Selection diagram] FIG. 4

Description

The present disclosure relates to, for example, a liquid level position sensor used for detecting the liquid level position of a liquid contained in a container, a liquid level position detecting method, and a program.

Conventionally, a sensor applying the measurement of capacitance is known in order to detect the position of the liquid level of the liquid contained in the container (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2013-167651

However, the conventional sensor may not be able to properly detect the liquid level position. Therefore, the present disclosure provides a liquid level position sensor or the like that can appropriately detect the liquid level position.

One aspect of the liquid level position sensor in the present disclosure is a liquid level position sensor that detects the liquid level position of the liquid contained in the container having the wall portion, and the positions in the vertical direction are different from each other and are along the wall portion. A measurement unit that measures the capacitance between the reference electrode and each of the plurality of measurement positions, and a calculation unit that detects the liquid level position based on the difference in the capacitance at the plurality of measurement positions. , Equipped with.

Further, one aspect of the liquid level position detecting method in the present disclosure is a liquid level position detecting method for detecting the liquid level position of a liquid contained in a container having a wall portion, and the positions in the vertical direction are different from each other. The liquid level position is detected based on the measurement step of measuring the capacitance between the reference electrode and the reference electrode at each of the plurality of measurement positions along the wall and the difference in the capacitance at the plurality of measurement positions. Includes arithmetic steps to be performed.

Further, one aspect of the present disclosure can also be realized as a program for causing a computer to execute the above-mentioned liquid level position detection method.

According to one aspect of the present disclosure, the liquid level position can be appropriately detected.

FIG. 1 is a diagram illustrating a usage example of the liquid level position sensor according to the embodiment. FIG. 2 is a first diagram illustrating a connection location to which the liquid level position sensor according to the embodiment is connected. FIG. 3 is a second diagram illustrating a connection location to which the liquid level position sensor according to the embodiment is connected. FIG. 4 is a block diagram showing a functional configuration of the liquid level position sensor according to the embodiment. FIG. 5 is a flowchart showing the operation of the liquid level position sensor according to the embodiment. FIG. 6A is a graph illustrating the capacitance measured for each measurement position in the embodiment. FIG. 6B is a graph illustrating the capacitance difference for each measurement position calculated in the embodiment.

(Background to disclosure)
There is a desire to detect the liquid level position of the liquid contained in the container. In particular, it is desired to be able to automatically manage the remaining amount of liquid in the container by automatically detecting the liquid level position. Further, it is more ideal that such detection of the liquid level position can be performed without touching (non-contacting) the liquid.

Therefore, conventionally, a capacitor is formed by a detection electrode (or simply referred to as an electrode) and a ground electrode (also referred to as a reference electrode) arranged on the outside of the container, and the capacitance of the capacitor is measured. , Sensors and the like that detect the liquid level position are known (Patent Document 1 and the like). This is based on the principle that the value of capacitance changes according to the amount of liquid in the container. That is, in the conventional sensor, a calibration curve showing the relationship between the liquid level position according to the amount of liquid in the container and the numerical value of the capacitance is obtained in advance, and the calibration curve is obtained from the measured capacitance. The liquid level position can be detected by reference.

However, in the conventional sensor, it is indispensable to obtain the calibration curve in advance. This is because the numerical value of the capacitance changes depending on the type of liquid to be contained and the components such as electrolytes (hereinafter, also referred to as the contents of the liquid), so that the calibration curve of one liquid is changed to that of another liquid. This is because it cannot be used as a calibration curve.

For this reason, the conventional sensor cannot detect the liquid level position for a liquid whose content is unknown or whose content is known but whose calibration curve has not been prepared. The calibration curve is created by measuring the capacitance in an empty container, measuring the capacitance in a full container, and preferably at a liquid level position located between the empty and full states. It is complicated because it is necessary to measure the capacitance step by step. It is also possible to use different empty and full containers for creating the calibration curve, but the influence of individual differences in the containers cannot be eliminated and the liquid level position cannot be detected accurately. In some cases.

Therefore, the liquid level position sensor according to the embodiment of the present disclosure described below measures the capacitance at each of a plurality of measurement positions having different positions in the vertical direction. The liquid level position sensor detects the liquid level position based on the difference in capacitance measured at each of the plurality of measurement positions.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. It should be noted that all of the embodiments described below show comprehensive or specific examples. The numerical values, shapes, materials, components, arrangement positions of the components, connection forms, steps, the order of steps, and the like shown in the following embodiments are examples, and are not intended to limit the present disclosure. In the following, terms indicating relationships between elements such as parallel and vertical, terms indicating the shape of elements such as rectangular shapes, and numerical ranges do not mean only strict meanings, but are substantially equivalent. It means that it includes a range, for example, a difference of about several percent.

Further, among the components in the following embodiments, the components not described in the independent claims are described as arbitrary components. Further, each figure used in the explanation is a schematic view and is not necessarily exactly illustrated. Further, in each figure, substantially the same configuration may be designated by the same reference numerals, and duplicate explanations may be omitted or simplified.

First, with reference to FIG. 1, a usage example of the liquid level position sensor according to the present embodiment and problems caused by the usage example will be described. FIG. 1 is a diagram illustrating a usage example of the liquid level position sensor according to the embodiment. FIG. 1 shows an example in which the liquid level position sensor 100 is applied to an automatic analyzer for a test sample. FIG. 1A shows an automated analyzer 200. Further, FIG. 1B shows the reagent rack 101 stored in the storage of the automated analyzer 200. Further, FIG. 1 (c) shows a container 102 placed on the reagent rack 101. In addition, in (c) of FIG. 1, a part is broken for visualization of the internal space 108. Only the outline of the broken part of the container 102 is shown by the alternate long and short dash line.

As shown in FIG. 1 (a), the liquid level position sensor 100 is used, for example, by being built in the automatic analyzer 200. The automatic analyzer 200 is an apparatus for automatically analyzing a test sample collected from a human body or the like. The automatic analyzer 200 is provided with a sample rack (not shown), and a plurality of sample containers containing test samples are placed in the sample rack. The automatic analyzer 200 is an apparatus that automatically analyzes a plurality of test samples by separating the test samples one by one from the sample container and analyzing them in the analysis unit 202. The test sample analyzed by the automatic analyzer 200 is, for example, a blood sample, a urine sample, a fecal sample, or the like. Further, the analysis unit 202 spectroscopically analyzes, for example, the reaction product of the test sample and the reagent. Therefore, the analysis unit 202 includes a reaction vessel (not shown), a spectroscope, a photodetector, and the like.

The reagent used for the reaction with the test sample is housed in the container 102 shown in FIG. 1 (c). More specifically, the reagent is contained as a liquid 104 in the internal space 108 of the container 102. The container 102 is made of a resin material such as polypropylene resin or polyethylene resin. The shape of the container 102 may be any shape as long as the internal space 108 is formed. In the present embodiment, the container 102 has a quadrangular prism shape having a trapezoidal cross section in a plane along the horizontal direction. The container 102 has a wall portion 103 extending across a horizontal plane. The liquid 104 is separated from a sampling port (not shown) configured to be openable and closable by a cap 105 or the like, and is subjected to a reaction with a test sample.

The wall portion 103 is a portion that covers the internal space 108 from the horizontal direction, and is in contact with the liquid 104 on the inner surface. Therefore, the wall portion 103 is made of a material having chemical resistance. Further, when the reagent has a property of being deteriorated by light, the wall portion 103 is formed of a material having a light-shielding property. In addition, "having a light-shielding property" means having a property of suppressing the transmission of at least a part of light by absorption or reflection. As a result, it may be substantially impossible to visually recognize the internal space 108 from the outside of the container 102 via the wall portion 103. Therefore, it may not be possible to visually detect the liquid level position of the liquid 104 from the outside of the wall portion 103. Further, the same problem may occur even when the storage 201 in which the container 102 is stored together with the reagent rack 101 has a light-shielding property.

In the present embodiment, the liquid level position sensor 100 detects the liquid level position of the liquid 104 housed in the internal space 108 of the container 102, but due to the above problem, the liquid level position is detected by the capacitance method. I do. In the present embodiment, an electrode forming a capacitor to be measured for capacitance is arranged on the outer surface of the wall portion 103 of the container 102 (that is, the surface opposite to the side in contact with the liquid 104). Specifically, on the outer surface of the wall portion 103, a plurality of electrodes 106 provided at a plurality of positions in the vertical direction and a reference electrode 107 are arranged. The electrode 106 and the reference electrode 107 are formed of, for example, a conductive metal such as copper or aluminum.

The reference electrode 107 is arranged as two sets that sandwich the plurality of electrodes 106 in the horizontal direction. The two reference electrodes 107 forming a set are set to the same potential in a short-circuited state. In this embodiment, the capacitance between the electrode 106 and the reference electrode 107 is measured. That is, each of the electrode 106 and the reference electrode 107 is electrically connected to the measuring instrument 93 for measuring the capacitance (see FIG. 4 described later).

For the sake of explanation, all the electrodes are shown in FIG. 1 (c) so that they can be seen. However, except for the contact point connected to the measuring instrument 93, a barcode or QR code (registered trademark) for identifying the reagent is used. A sticker printed with a two-dimensional bar code or the like may be affixed from above the electrode 106.

In FIG. 1 (c), the electrodes 106 are arranged over substantially the entire area from the lower side to the upper side in the vertical direction of the container 102, and the capacitance at the measurement position where the electrodes 106 are arranged is measured at each electrode 106. To. As described above, the electrodes 106 have different positions in the vertical direction from each other, and are provided at each of the plurality of measurement positions along the wall portion 103. The position where the electrode 106 is arranged may be a position according to the purpose of using the liquid level position sensor 100. That is, when it is desired to confirm whether or not the liquid 104 is in a full state, the electrode 106 is arranged only above the central portion in the vertical direction of the container, and when it is desired to confirm whether or not the liquid 104 is in an empty state. , May be placed only below the center of the container in the vertical direction.

The former is applied when the liquid 104 is stored (injected) in the container 102, and the measurement position is set above the central portion in the vertical direction of the container 102. Further, the latter is applied when the liquid 104 is separated (drained) from the container 102, and the measurement position is set below the central portion in the vertical direction of the container 102. Further, when it is desired to detect the liquid level position in the entire range from the full state to the empty state, the electrodes 106 are arranged over substantially the entire area from the lower side to the upper side in the vertical direction of the container 102 as in the present embodiment.

As shown in FIG. 1 (b), a plurality of containers 102 are placed on the reagent rack 101. Since a plurality of types of reagents are used for the analysis of the test sample, the plurality of types of reagents are contained in the plurality of containers 102 placed on the reagent rack 101. In order to separate and react a part of each of a plurality of types of reagents for each test sample, the liquid level position is sequentially detected in the container 102 of the used reagents. , It was necessary to prepare calibration curves for all reagents in advance.

The reagent rack 101 is configured to have a circular shape when viewed from the vertical direction, and together with a trapezoidal shape having a cross section along the horizontal direction of the container 102, when a plurality of containers 102 are placed, the plurality of containers 102 rotate around the container 102. It is designed to line up along the direction. With such a configuration, the reagent rack 101 rotates and moves the placed container 102. That is, the reagent rack 101 is an example of a moving table according to the embodiment.

By rotating the reagent rack 101, the liquid 104 is separated from the container 102 that has been moved to the predetermined position of the automatic analyzer 200 by a sorting device (not shown) provided corresponding to the predetermined position. That is, the sorting device can move to a predetermined position and inject the sorted liquid 104 into the reaction vessel of the analysis unit 202 to be subjected to the reaction in the analysis unit 202. In this way, by moving the container 102 by the reagent rack 101, a plurality of reagents can be sorted by one sorting device, and the automated analyzer 200 can be realized with a simple configuration.

Here, since the reagent rack 101 is configured to move the container 102 independently of the measuring instrument 93 constituting the liquid level position sensor 100, the electrodes 106, the reference electrode 107, and the measuring instrument 93 arranged in the container 102 are used. It is difficult to maintain an electrical connection at all times. Therefore, in the liquid level position sensor 100 according to the present embodiment, the electrode 106, the reference electrode 107, and the measuring instrument 93 can be physically separated from each other as needed. Details of the connection between the electrode 106 and the reference electrode 107 and the measuring instrument 93 will be described later.

Further, the reagent often needs to be stored at a low temperature until immediately before the reaction, and for this reason, the storage 201 may be provided with a refrigerating function. When dew condensation is caused by the cooled reagent, a short circuit may occur when the electrode 106 and the reference electrode 107 are physically connected to the measuring instrument 93, and the capacitance may not be measured normally. Therefore, in the present embodiment, the electrode 106 and the reference electrode 107 are physically connected to the measuring instrument 93 at a portion of the container 102 where dew condensation is relatively unlikely to occur.

This configuration will be described in detail with reference to FIG. FIG. 2 is a first diagram illustrating a connection location to which the liquid level position sensor according to the embodiment is connected. FIG. 2A is a diagram showing an electrode array 120 including an electrode 106 and a reference electrode 107 arranged outside the wall portion 103 of the container 102. Note that FIG. 2A shows a view of the electrode array 120 as viewed from the container 102 side. Further, FIG. 2B is a diagram showing a cut surface of the electrode array 120 when cut along the line BB shown in FIG. 2A.

In the present embodiment, the electrode 106 and the reference electrode 107 are used in a state of being integrated as the electrode array 120 shown in FIG. 2 (a). As a result, the distances between the plurality of electrodes 106, the two reference electrodes 107, and between the electrodes 106 and the reference electrode 107 can be appropriately provided. The electrode 106 and the reference electrode 107 are patterned on a film 115 such as resin or paper. Therefore, the electrode 106 and the reference electrode 107 are integrated by the film 115.

The electrode array 120 has a sheet shape including the electrode 106 and the reference electrode 107, and is fixed to the container 102 by being attached to the outside of the wall portion 103 of the container 102, for example. When the container 102 is labeled with the contents of the reagent, the electrode 106, the reference electrode 107, the film 115, and other members constituting the electrode array 120 are preferably transparent. That is, when the electrode array 120 is attached from above the label, the label is visibly configured via the transparent electrode array 120.

Here, since the electrode 106 and the reference electrode 107 measure the liquid 104 facing each other via the wall portion 103, for example, the liquid 104 is emptied from the liquid level position when the specified amount of the liquid 104 at the time of shipment of the reagent is contained. It is formed at a position outside the wall portion 103 corresponding to the liquid level position where the liquid 104 can be stored up to the liquid level position (the position of the bottom of the container 102). The liquid 104 may be cooled as described above, and there is a high possibility that dew condensation will occur at the liquid level position where the liquid 104 can be accommodated. On the other hand, for example, on the upper side in the vertical direction from the liquid level position when the specified amount of the liquid 104 at the time of shipment of the reagent is contained, it is unlikely that the liquid 104 is located inside the wall portion 103, and dew condensation occurs. It is unlikely to occur. Therefore, in the present embodiment, the connection points between the electrode 106 and the reference electrode 107 and the measuring instrument 93 are set at positions where the possibility of dew condensation is low.

As shown in FIG. 2A, contact points 111 corresponding to each of the plurality of electrodes 106 are provided at the connection points between the electrodes 106 and the measuring instrument 93. Further, the contact 111 and the electrode 106 are electrically connected by a conductive wire 109. At the connection point between the reference electrode 107 and the measuring instrument 93, a reference contact 112 corresponding to each of the reference electrodes 107 is provided. Further, the reference contact 112 and the reference electrode 107 are electrically connected by a conductive wire 113.

For example, as shown in FIG. 2A, the conductive wire 109 and the conductive wire 113 extend so as not to come into contact with the other electrodes 106, the reference electrode 107, the conductive wire 109, and the conductive wire 113. The conductive wire 109 electrically connected to the lower electrode 106 in the vertical direction extends between, for example, the electrode 106 and the reference electrode 107. With this configuration, as shown in FIG. 2B, a relatively thin electrode array 120 having only the thickness of the electrode 106 and the reference electrode 107 and the thickness of the film 115 integrating them can be realized. ..

In addition, the measurement of capacitance is easily affected by external noise. Therefore, in the electrode array 120 used in the present embodiment, the guard electrode covering the electrode 106 and the reference electrode 107 is provided on the outer side of the electrode 106 and the reference electrode 107, that is, on the side opposite to the side in contact with the wall portion 103. 114 is provided. The guard electrode 114 may individually cover each electrode 106 or each reference electrode 107, or may integrally cover each electrode 106 or as shown in the figure. By providing the guard electrode 114, it is less likely to be affected by noise from the outside, so that it is possible to measure the capacitance with higher accuracy. A label indicating the contents of the reagent may be attached to the position of the guard electrode 114 or the outer side of the guard electrode 114.

Further, the configuration of the conductive wire is not limited to this, and any configuration can be applied as long as it extends so as not to come into contact with the other electrode 106, the reference electrode 107, the conductive wire 109, and the conductive wire 113. Another example of the configuration of the conductive wire will be described with reference to FIG. FIG. 3 is a second diagram illustrating a connection location to which the liquid level position sensor according to the embodiment is connected. FIG. 3A is a diagram showing an electrode array 120a in which the arrangement of the conductive wires 109a is different from that in FIG. 2A when viewed from the same viewpoint. Further, FIG. 3B is a diagram showing a cut surface of the electrode array 120a when cut along the line BB shown in FIG. 3A. Here, the points that differ from the description of FIG. 2 will be mainly described, and the overlapping points will be omitted or simplified.

In this example, the arrangements of the conductive wire 109a and the conductive wire 113a are different. More specifically, as shown in FIG. 3B, the conductive wire 109a extends in a layer different from the layer in which the electrode 106 and the reference electrode 107 are formed, and is shown in FIG. 3A. It overlaps with the electrode 106 in a plan view. By doing so, even in the electrode array 120a having more electrodes 106, the conductive wires 109a can be prevented from coming into contact with each other while maintaining a sufficient thickness. That is, even in the electrode array 120a in which a large number of electrodes 106 are provided and a large number of conductive wires 109a are required, the contact 111 or the reference contact 112 and the electrode 106 or the reference electrode 107 can be appropriately electrically connected. can. Further, since the distance between the electrode 106 and the reference electrode 107 can be shortened, it is easy to secure the capacitance value required for liquid detection.

Next, with reference to FIG. 4, the configuration of the liquid level position sensor 100 according to the present embodiment will be described. FIG. 4 is a block diagram showing a functional configuration of the liquid level position sensor according to the embodiment. In FIG. 4, in addition to the liquid level position sensor 100, the electrode array 120 and the container 102 described above are also shown. In FIG. 4, for convenience of explanation, the electrode 106 will be described separately as three electrodes, the first electrode 106a to the third electrode 106c. Hereinafter, the first electrode 106a to the third electrode 106c are referred to as electrodes 106 without distinction only when it is not necessary to use them properly. Further, in FIG. 4, for convenience of explanation, the contact 111 will be described separately for the three electrodes of the first contact 111a to the third contact 111c. Hereinafter, the first contact 111a to the third contact 111c will be referred to as contact 111 without distinction only when it is not necessary to use them properly.

As shown in FIG. 4, the liquid level position sensor 100 includes a measuring unit 90, a calculation unit 80, and a driving unit 70.

The measuring unit 90 is a functional unit that measures the capacitance between each electrode 106 and the reference electrode. The measuring unit 90 includes a terminal including a connection terminal 91a, a connection terminal 91b, and a connection terminal 91c, a reference terminal 92, and a measuring instrument 93.

The connection terminals 91a to 91c are electrically connected to the corresponding electrodes 106, respectively. Specifically, the connection terminal 91a is electrically connected to the first electrode 106a via the first contact 111a. Further, the connection terminal 91b is electrically connected to the second electrode 106b via the second contact 111b. Further, the connection terminal 91c is electrically connected to the third electrode 106c via the third contact 111c.

The reference terminal 92 is electrically connected to the reference electrode 107 via the reference contact 112. The measuring instrument 93 is a capacitance meter that measures the capacitance between the terminal and the reference terminal 92, and is realized by using, for example, an LCR meter or the like. The measuring instrument 93 indirectly measures the capacitance between the electrode 106 and the reference electrode 107, each of which is electrically connected, by measuring the capacitance between the terminal and the reference terminal 92. Is going.

Here, the electrical connection between the measuring instrument 93 and the electrode 106 and the reference electrode 107 can be separated. More specifically, the other end side of the terminal whose one end is electrically connected to the measuring instrument 93 and the other end side of the contact 111 whose one end is electrically connected to the electrode 106 can be physically separated from each other. .. A drive unit 70 is provided to switch between physical connection and non-connection between the other ends.

The drive unit 70 is an actuator that applies a driving force for moving the measurement unit 90. When the reagent rack 101 rotates and the container 102 moves, the drive unit 70 drives the measurement unit 90 in the direction of the white left arrow in the figure to separate the physical connections between the other ends. .. Further, when the rotation of the reagent rack 101 is completed and the container 102 is stopped, the drive unit 70 drives the measurement unit 90 in the direction of the white arrow in the figure to physically drive the other ends of the reagent rack 101. Connect to the target. In this way, the drive unit 70 drives the measurement unit 90 so that the measurement unit 90 does not interfere with the rotation of the reagent rack 101, and both the measurement of the capacitance and the rotation of the reagent rack 101 are compatible. ing.

Here, in the use case of FIG. 1A, the measuring unit 90 is arranged at a position corresponding to the sorting device. In this use case, the change in the liquid level position of the liquid 104 occurs before and after the sorting by the sorting device, and the container 102 sorted by the sorting device is in the position corresponding to the sorting device. Stop at. That is, according to this configuration, the liquid level position is immediately detected for the container 102 that is stopped due to the liquid sorting by the sorting device and the liquid level position of the liquid 104 changes. Can be done.

Further, the connection ends of the plurality of terminals with the contact 111 are arranged on one virtual surface S1. Further, the connection ends of the plurality of contacts 111 with the terminals are arranged on the virtual surface S2 parallel to the virtual surface S1. As a result, the plurality of terminals and the plurality of contacts 111 can be connected to each other at the same time. At this time, the connection ends of the reference terminal 92 with the reference contact 112 are also arranged on the virtual surface S1, and the connection ends of the reference contact 112 with the reference terminal 92 are also arranged on the virtual surface S2. The reference terminal 92 and the reference contact 112 are also connected in the same manner.

In the present embodiment, the capacitance between the plurality of electrodes 106 and the reference electrode 107 is measured at each of the plurality of electrodes 106. If each connection is switched by the drive unit 70, it takes a relatively long time to measure the capacitance. In the present embodiment, by making physical connections at the same time, the speed is controlled by the measurement by the measuring instrument 93, which is completed in a relatively short time. That is, this configuration makes it possible to measure the capacitance more quickly. Further, when the measuring unit 90 includes a plurality of measuring instruments 93, the measurement by the measuring instruments 93 can be performed in parallel.

The capacitance measured by the measuring unit 90 is analyzed by the arithmetic unit 80 communication-connected to the measuring unit 90, and the liquid level position is detected. The arithmetic unit 80 is, for example, an arithmetic unit such as a computer including a processor and a memory. The calculation unit 80 identifies the measurement position indicating the capacitance corresponding to the liquid level position from the plurality of measurement positions corresponding to each of the plurality of electrodes 106 and the capacitance measured at the measurement position. .. As a result, the calculation unit 80 detects the liquid level position from the specified measurement position.

Hereinafter, the operation of the calculation unit 80 will be described in detail by referring to FIG. 5 as well. FIG. 5 is a flowchart showing the operation of the liquid level position sensor according to the embodiment.

As described above, the liquid level position sensor 100 measures the capacitance between the reference electrode 107 and the electrode 106 provided along the wall portion 103 by being attached to the wall portion 103. This measurement is performed at each of the plurality of electrodes 106 having different positions in the vertical direction (for example, the vertical direction of the paper surface in FIG. 4). That is, in the present embodiment, the capacitance is measured at each of the measurement positions where each of the plurality of electrodes 106 is arranged.

In the example of the electrode array 120 shown in FIG. 4, the measuring unit 90 measures the capacitance at the first position, which is the measuring position where the first electrode 106a is arranged (step S101). Similarly, the measuring unit 90 measures the capacitance at the second position, which is the measuring position where the second electrode 106b is arranged (step S102). Further, in the same manner, the measuring unit 90 measures the capacitance at the third position, which is the measuring position where the third electrode 106c is arranged (step S103). If other electrodes 106 are present, the measuring unit 90 measures the same capacitance for all the electrodes 106 including them (measurement step). The measurement order for each electrode 106 in this measurement step is not particularly limited. The measuring unit 90 may measure in order from the first position to the third position, may measure in order from the third position to the first position, or may measure randomly from the second position. ..

Subsequently, the calculation unit 80 acquires the measurement results of all the capacitances and calculates the difference in the capacitances at the adjacent measurement positions (step S104). Specifically, in the example of the electrode array 120 shown in FIG. 4, the calculation unit 80 calculates the difference between the capacitance at the first position and the capacitance at the second position, and at the second position. The difference between the capacitance and the capacitance at the third position is calculated. The calculation unit 80 calculates the difference between the capacitances of the adjacent electrodes 106 by using the measurement results of the capacitances of each of the at least three electrodes 106 shown in this example. When electrodes exist in addition to the first electrode 106a to the third electrode 106c described above, the calculation unit 80 similarly calculates the difference between the capacitances of the adjacent electrodes 106 for those capacitances. do.

Subsequently, the calculation unit 80 identifies a position set that is a set of adjacent measurement positions (or electrodes 106) that maximizes the difference in the calculated capacitance (step S105). The liquid level position exists between the measurement positions where the difference in capacitance is maximum. From this, the calculation unit 80 detects the position sandwiched between the measurement positions forming the set as the liquid level position in the specified position set (step S106). As an example, the calculation unit 80 detects an intermediate position in the vertical direction between the measurement positions forming a set in the specified position set as the liquid level position. If, for example, the component of the liquid 104 is known and the tendency to be biased to either the upper side or the lower side in the vertical direction is empirically known, the calculation unit 80 may make a correction according to the tendency. Further, correction may be performed based on other measured values related to the liquid level position.

As described above, the calculation unit 80 detects the liquid level position based on the difference in the measured capacitance (calculation step).

A specific example of detecting the liquid level position based on the simulation is shown with reference to FIGS. 6A and 6B. FIG. 6A is a graph illustrating the capacitance measured for each measurement position in the embodiment. Further, FIG. 6B is a graph illustrating the capacitance difference for each measurement position calculated in the embodiment.

The graph shown in FIG. 6A shows the values of capacitance expected to be measured at each of the plurality of electrodes 106. More specifically, the graph shows the capacitance values measured at the electrodes 106 installed at 13 locations where the position (that is, height) from the bottom in the vertical direction is within the range of 0 to 60 mm. ing. Further, at this time, it is assumed that water having a relative permittivity of 80 as the liquid 104 is stored in the container 102 so that the liquid level position is at the position of 28 mm. The size of the container is calculated assuming that the trapezoidal shape of the cross section along the horizontal direction is an isosceles trapezoid having an upper base of 5 mm and a lower base of 15 mm, and the height in the vertical direction is 90 mm. Further, in the simulation, the distance between the container 102 and the electrode 106 is from 0.1 mm, which is a hypothetical distance between the container 102 and the electrode 106 when the container 102 is adhered, to 3.0 mm, which is the distance between the container 102 and the electrode 106. The results of each change are shown.

As shown in the figure, a relatively high capacitance value is shown at the measurement position on the lower side in the vertical direction than when the liquid level position (28 mm) is reached. At the measurement position on the upper side in the vertical direction beyond the liquid level position, the value is lower than the value of the capacitance measured at the measurement position on the lower side in the vertical direction. Further, it can be seen that a substantially constant capacitance value can be obtained except for the vicinity of the liquid level position as a whole. This pattern is brought about by the difference in dielectric constant between the liquid 104 contained in the internal space 108 and the air occupying above it. That is, the high capacitance value is measured by the liquid 104 having a higher dielectric constant than the air below the liquid level position in the vertical direction, and the capacitance value of the air is measured above the liquid level position in the vertical direction. Will be done. Therefore, the graph in the figure in which the value of the capacitance changes suddenly at the liquid level position is drawn.

As described above, the liquid level position sensor 100 of the present embodiment can be applied to any liquid 104 as long as it has a difference in dielectric constant from air. Further, even if the dielectric constant of the liquid 104 is close to the dielectric constant of air, it has a dielectric constant different from that of air, such as constructing a system in which air is replaced with argon gas (more preferably, it has low reactivity). ) By using a gas, it is possible to detect the liquid level position of substantially any liquid 104.

As shown in the figure, the distance between the container 102 and the electrode 106 directly affects the measurement sensitivity of the capacitance, so any combination of a liquid 104 and a gas having similar dielectric constants is possible. It is preferable that the distance between the container 102 and the electrode 106 is as close as possible.

As described above, in the present embodiment, the liquid level position is detected by applying the fact that the capacitance changes above and below the liquid level position in the vertical direction. In order to capture this change, the arithmetic unit 80 calculates the difference in capacitance measured at each of the two electrodes 106 that form an adjacent (in other words, vertically arranged vertically) pair. FIG. 6B shows a graph of the capacitance difference with respect to the measurement position. Whereas the number of plots in the graph of FIG. 6A is 13 corresponding to the number of electrodes 106, this figure shows a graph of the number of 12 plots resulting from each difference. The measurement position here is an intermediate point between the two measurement positions forming the set in FIG. 6A.

As shown in the figure, a graph in which the capacitance difference is one peak is drawn according to the sudden change in the capacitance value in FIG. 6A. This peak location corresponds to the position set with the greatest change, i.e., to the switching of capacitance across liquid level positions. That is, it can be estimated that the liquid level position exists between the two measurement positions forming the set of the position set having the largest capacitance difference. In this way, the liquid level position sensor 100 according to the present embodiment detects the liquid level position. As described above, the liquid level position between the position sets may be an intermediate point between the two measurement positions forming the position set, and the peak in the capacitance difference graph as shown in FIG. 6B. A more accurate position may be calculated by Gaussian fitting analysis using plots of several points around.

As described above, in the liquid level position sensor 100 in the present embodiment, the liquid level position is simply changed by the change in capacitance according to the liquid level position of the liquid 104 to be stored without creating a calibration curve or the like. Detected. That is, the liquid level position sensor 100 can appropriately detect the liquid level position regardless of the content of the liquid 104.

As described above, the liquid level position sensor 100 according to the present embodiment is a liquid level position sensor 100 that detects the liquid level position of the liquid 104 housed in the container 102 having the wall portion 103, and is vertical to each other. Based on the difference between the measurement unit 90 that measures the capacitance between the reference electrode 107 and the plurality of measurement positions along the wall portion 103 and the difference in capacitance at the plurality of measurement positions. , A calculation unit 80 for detecting the liquid level position, and the like.

Such a liquid level position sensor 100 can detect the liquid level position by using the difference in capacitance measured at each of the plurality of measurement positions in the vertical direction of the container 102. The capacitance measured here is measured as a different value of one value and another depending on whether it is above or below the liquid level position in the vertical direction. Therefore, it is possible to estimate the location where the capacitance changes significantly due to the difference in capacitance. Therefore, the liquid level position sensor 100 can appropriately detect the liquid level position regardless of the content of the liquid and without creating a calibration curve.

The calculation unit 80 identifies the position set in which the difference in capacitance measured at each of the two measurement positions is the largest among the position sets consisting of two adjacent measurement positions in the plurality of measurement positions. In the vertical direction, the position between the two measurement positions of the specified position set is detected as the liquid level position.

According to this, based on the difference in capacitance, it is possible to identify a position set in which the value between two capacitances measured at adjacent measurement positions shows the maximum change. Since the capacitance shows the maximum change at the position corresponding to the liquid level position, it can be estimated that the liquid level position exists at the position between the two measurement positions forming the position set specified above, and the calculation unit 80. Can detect the liquid level position based on this estimation. Therefore, the liquid level position sensor 100 can appropriately detect the liquid level position.

At least one of the container 102 and the storage 201 in which the container 102 is stored when the container 102 is used is made of a light-shielding material.

According to this, since the container 102 or the storage 201 for storing the container 102 is made of a light-shielding material, the liquid level position is appropriately detected even when the liquid level position is detected based on the capacitance. be able to.

The measuring unit 90 includes a terminal electrically connected to a plurality of electrodes 106 corresponding to each of the plurality of measurement positions, a reference terminal 92 electrically connected to the reference electrode 107, and a terminal and a reference terminal 92. It has a measuring instrument 93 for measuring the capacitance between them.

According to this, the measuring instrument 93 can indirectly measure the capacitance between the electrode 106 and the reference electrode 107 by measuring the capacitance between the terminal and the reference terminal 92.

The container 102 is placed on a moving table that moves the container 102, and the liquid level position sensor 100 further drives the measuring unit 90 while the moving table is moving the container 102, so that the plurality of electrodes 106 and terminals are connected. A drive unit 70 is provided which separates the reference electrode 107 and the reference terminal 92.

According to this, the connection between the measuring instrument 93 and the electrode 106 and the reference electrode 107 suppresses the load on each connection portion involved in the connection and the restriction on the movement of the container 102 by the moving table. Therefore, it is possible to achieve both the movement of the container 102 by the moving table and the measurement of the capacitance by the measuring instrument 93 independent of the moving table.

The terminal includes a plurality of connection terminals (for example, connection terminal 91a and the like) corresponding to each of the plurality of electrodes 106, and each of the plurality of connection terminals is electrically connected to the corresponding plurality of electrodes 106 at the same time.

According to this, electrical connection to each of the measuring instruments 93 of the plurality of electrodes 106 is performed at the same time, and the measurement of the capacitance in all of the plurality of electrodes 106 can be used for the measurement of the capacitance in the measuring instrument 93. It can be rate-determining. Capacitance measurement with the measuring instrument 93 can be performed quickly by switching the circuit with a switch element or by parallel processing with a plurality of measuring instruments 93, so that the capacitance can be measured quickly. ..

Each of the plurality of electrodes 106 is electrically connected to the conductive wire 109 and is electrically connected to the terminal via the conductive wire 109 at a position different from the position corresponding to the measurement position.

According to this, even when there is a physical or electrical failure in the electrical connection at the position corresponding to the measurement position, etc., the measuring instrument 93 and the electrode 106 and the reference electrode 107 are appropriately electrically connected. Connection can be realized.

The plurality of measurement positions are located above the vertical center portion of the container 102.

According to this, it is possible to detect the liquid level position in a full state, which is usually set at a position above the central portion of the vertical method of the container 102.

The plurality of measurement positions are located below the vertical center portion of the container 102.

According to this, it is possible to detect the liquid level position in an empty state, which is usually set at a position below the central portion of the vertical method of the container 102.

Further, the liquid level position detecting method according to the present embodiment is a liquid level position detecting method for detecting the liquid level position of the liquid contained in the container having a wall portion, and the positions in the vertical direction are different from each other, and the wall A measurement step for measuring the capacitance between the reference electrode and each of the plurality of measurement positions along the section, and a calculation step for detecting the liquid level position based on the difference in capacitance at the plurality of measurement positions. ,including.

According to this, the same effect as that of the liquid level position sensor 100 can be obtained.

Further, the program according to the present embodiment is a program for causing a computer to execute the liquid level position detecting method described above.

According to this, the same effect as the above-mentioned liquid level position detection method can be obtained by using a computer.

(Other embodiments)
Although the embodiments have been described above, the present disclosure is not limited to the above embodiments.

The liquid level position sensor according to the above embodiment has been described by using an example applied to the automatic analyzer 200 as a use case, but the liquid level position sensor can be used in any application as long as the liquid is contained in the container. It can be applied to devices, systems, etc.

Further, as described with reference to FIG. 6A, if the difference in dielectric constant between the liquid and the gas contained in the internal space of the container is sufficient, it is not necessary to bring the electrode arrays into contact with each other. Therefore, the electrode array may be brought close to the simple container by a driving unit or the like for measurement, and the electrode array may be retracted when the container moves.

Also, for example, it is not necessary for the container to be provided with electrodes, and the capacitance is continuously measured by scanning the probe connected to the measuring instrument in the vertical direction along the wall of the container. The liquid level position may be detected based on the difference between the measured value of the above and the measured value immediately before the continuation.

Further, in the above embodiment, the liquid level position sensor is realized by a single device, but may be realized as a plurality of devices. For example, the liquid level position sensor may be realized as a liquid level position detection system composed of a single detection device corresponding to a detection unit and a calculation device (or a computer) corresponding to a calculation unit. When the liquid level position sensor is realized by a plurality of devices, the components included in the liquid level position sensor may be distributed to the plurality of devices in any way.

For example, the communication method between the devices in the above embodiment is not particularly limited. Further, in the communication between the devices, a relay device (including a broadband router) (not shown) may intervene.

Further, in the above embodiment, another processing unit may execute the processing executed by the specific processing unit. Further, the order of the plurality of processes may be changed, or the plurality of processes may be executed in parallel. Further, in the above embodiment, the operation examples may be arbitrarily combined.

Further, in the above embodiment, each component may be realized by executing a software program suitable for each component. Each component may be realized by a program execution unit such as a CPU or a processor reading and executing a software program recorded on a recording medium such as a hard disk or a semiconductor memory.

In addition, each component may be realized by hardware. For example, each component may be a circuit (or integrated circuit). These circuits may form one circuit as a whole, or may be separate circuits from each other. Further, each of these circuits may be a general-purpose circuit or a dedicated circuit.

In addition, the general or specific aspects of the present disclosure may be realized in a recording medium such as a system, an apparatus, a method, an integrated circuit, a computer program, or a computer-readable CD-ROM. Further, it may be realized by any combination of a system, an apparatus, a method, an integrated circuit, a computer program and a recording medium.

For example, the present disclosure may be realized as a liquid level position detection method executed by a liquid level position sensor, or may be realized as a program for causing a computer to execute such a liquid level position detection method. Further, the present disclosure may be realized as a computer-readable non-temporary recording medium in which such a program is recorded.

In addition, it is realized by applying various modifications to each embodiment that can be conceived by those skilled in the art, or by arbitrarily combining the components and functions of each embodiment within the scope of the purpose of the present disclosure. Also included in this disclosure.

The liquid level position sensor in the present disclosure is widely used as a liquid level position sensor used for detecting the liquid level position of the liquid contained in the container.

70 Drive unit 80 Calculation unit 90 Measuring unit 91a Connection terminal 91b Connection terminal 91c Connection terminal 92 Reference terminal 93 Measuring instrument 100 Liquid level position sensor 101 Reagent rack 102 Container 103 Wall 104 Liquid 105 Cap 106 Electrode 106a 1st electrode 106b 2nd Electrode 106c Third electrode 107 Reference electrode 108 Internal space 109, 109a, 113, 113a Conductive wire 111 Contact 111a First contact 111b Second contact 111c Third contact 112 Reference contact 114 Guard electrode 115 Film 120, 120a Electrode array 200 Automatic analysis Equipment 201 Storage 202 Analysis unit S1 Virtual surface S2 Virtual surface

Claims (11)

A liquid level position sensor that detects the liquid level position of a liquid contained in a container having a wall portion.
A measurement unit that measures the capacitance between the reference electrode and the measurement unit at each of the plurality of measurement positions along the wall portion, which have different positions in the vertical direction from each other.
A liquid level position sensor including a calculation unit for detecting the liquid level position based on the difference in capacitance at the plurality of measurement positions. The arithmetic unit
Among the position sets consisting of two adjacent measurement positions in the plurality of measurement positions, the position set having the maximum difference in the capacitance measured at each of the two measurement positions is specified.
The liquid level position sensor according to claim 1, wherein a position sandwiched between two measurement positions of the specified position set in the vertical direction is detected as the liquid level position. The liquid level position sensor according to claim 1 or 2, wherein at least one of the container and the storage in which the container is stored when the container is used is made of a light-shielding material. The measuring unit
Terminals that are electrically connected to a plurality of electrodes corresponding to each of the plurality of measurement positions, and
A reference terminal electrically connected to the reference electrode and
The liquid level position sensor according to any one of claims 1 to 3, comprising a measuring instrument for measuring a capacitance between the terminal and the reference terminal. The container is placed on a moving table for moving the container, and the container is placed on a moving table.
The liquid level position sensor further separates the plurality of electrodes from the terminal by driving the measuring unit while the moving table is moving the container, and the reference electrode and the reference terminal are separated from each other. The liquid level position sensor according to claim 4, further comprising a drive unit for pulling away. The terminal includes a plurality of connection terminals corresponding to each of the plurality of electrodes.
The liquid level position sensor according to claim 5, wherein each of the plurality of connection terminals is electrically connected to the corresponding plurality of electrodes at the same time. Each of the plurality of electrodes
Electrically connected to the conductive wire,
The liquid level position sensor according to any one of claims 4 to 6, which is electrically connected to the terminal via the conductive wire at a position different from the position corresponding to the measurement position. The liquid level position sensor according to any one of claims 1 to 7, wherein the plurality of measurement positions are located above the central portion in the vertical direction of the container. The liquid level position sensor according to any one of claims 1 to 7, wherein the plurality of measurement positions are located below the central portion in the vertical direction of the container. It is a liquid level position detecting method for detecting the liquid level position of a liquid contained in a container having a wall portion.
A measurement step for measuring the capacitance between the reference electrode and each of the plurality of measurement positions along the wall portion, which are located at different positions in the vertical direction from each other.
A liquid level position detecting method including a calculation step for detecting the liquid level position based on the difference in capacitance at the plurality of measurement positions. A program for causing a computer to execute the liquid level position detecting method according to claim 10.

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