JPH059652Y2 - - Google Patents

Description

[Detailed explanation of the idea] [Industrial application field] The present invention relates to improvements in sheet-type conductivity meters.

[Conventional technology]

Recently, sheet-type conductivity meters in which conductivity measurement electrodes are formed into sheets have been developed and are being put into practical use (for example, Utility Model Application No. 191496/1983).
(Refer to Utility Model Publication No. 63-96455).

This sheet-type conductivity meter has the excellent advantage of being able to measure conductivity simply by placing an extremely small amount (for example, approximately 0.1 m) of the test liquid on the surface of the conductivity measurement electrode. ing.

[The problem that the idea aims to solve]

However, according to the inventor's research, it was found that this sheet type conductivity meter has the following problems.

That is, as shown in FIG. 8, with the test liquid S dropped on a pair of conductivity measuring electrodes 52, 52 formed on a sheet 51, the conductivity measuring electrodes 52, 5 are
2, ion conduction occurs in the test liquid S, and the current density at that time decreases as it moves away from the conductivity measurement electrodes 52, 52, as shown by curve D... The current density near the surface of the liquid S is smaller than that near the surfaces of the conductivity measuring electrodes 52, 52. Furthermore, since the current flows along the edges of the test liquid S, the current distribution varies depending on the shape of the test liquid S.

The difference in current density near the surface of the test solution S and the surface of the conductivity measurement electrodes 52, 52 is sufficiently large when the amount of the test solution S is large, but is not too large when the amount of the test solution S is small. In this case, the difference in current distribution near the surface of the test liquid S due to the shape of the test liquid S has a large effect on the total current.

Therefore, in the case where the conductivity measuring electrodes 52, 52 are simply formed on a flat sheet 51 as described above, it is difficult to make the shape of the test liquid S constant. The cell constant of the conductivity measuring electrodes 52, 52 varies depending on the physical shape, making it difficult to perform conductivity measurements with reproducibility.

The present invention was developed with the above-mentioned considerations in mind, and its purpose is to provide a sheet-type conductivity meter that can measure conductivity with good reproducibility without sacrificing the advantages mentioned at the beginning. It is about providing.

[Means to solve the problem]

In order to achieve the above object, the sheet-type conductivity meter according to the present invention has a concave measuring cell with a small capacity formed in the measuring part, and a conductivity measuring electrode is provided on the bottom surface of the measuring cell.

[Effect]

According to the above configuration, the current distribution of the test liquid becomes the total current within the concave measurement cell, and the current in the test liquid that overflows to the outside of the concave measurement cell can be ignored. Therefore, there is no possibility that the cell constant will fluctuate from measurement to measurement, and conductivity measurements can be performed with good reproducibility.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

1 and 2 show a sheet-type conductivity meter according to a first embodiment of the present invention. In both figures, 1 is a main body, and a concave measuring cell 3 with a small capacity is formed in the measuring part 2. A pair (two) of conductivity measuring electrodes 4A and 4B are provided on the bottom surface of this measuring cell 3.

The above measurement cell 3 and conductivity measurement electrodes 4A, 4B
is formed, for example, as follows. That is, a pair of electrodes are formed by applying Ag paste by, for example, a printing method to the upper surface of a substrate 5 made of a material that has sufficiently high insulating properties even when immersed in a solution containing an electrolytic substance, such as polyethylene terephthalate (PET). Then, the surfaces of these electrodes are plated with platinum black to form conductivity measuring electrodes 4A and 4B, and Ag paste is applied to the back surface of the substrate 5 by a printing method to form conductivity measuring electrodes 4A and 4B, respectively. Continuous lead portions 6A and 6B are formed. As shown in FIG.
A and 4B sides are made to be slightly lower (1 to 2 mm), and an insulating part 7 made of a highly insulating material such as PET is formed around the conductivity measuring electrodes 4A and 4B, so that a concave part having, for example, a circular shape in plan view is formed. The measurement cell 3 has conductivity measurement electrodes 4A and 4B on the bottom surface of this recess. In addition, in Figure 2, 8
1 is a lower case, and 9 and 10 are insulating parts made of a highly insulating material.

The measurement cell 3 ensures that the shape of the portion of the surface of the test liquid S filled therein that is in contact with the measurement cell 3 is always constant.

That is, in the upper part of the measurement cell 3, the test liquid S
is not in contact with the measurement cell 3, therefore, the test liquid S
The shape of the surface is not constant. However, since the conductivity measuring electrodes 4A and 4B are provided on the bottom surface of the measuring cell 3, the current density near the top of the measuring cell 3 is small, and if the height of the insulating part 7 is set to a certain level, it will hardly affect the cell constant. is not affected.

The height required for the insulating section 7 is the height of the measuring cell 3.
It varies depending on the bottom surface and the size of the conductivity measuring electrodes 4A, 4B. For example, the bottom of measurement cell 3 has a diameter of 6 mm.
When the conductivity measuring electrodes 4A and 4B are both 1 mm x 1 mm square and the distance between the electrodes 4A and 4B is 0.5 mm, the height is about 3 mm. Therefore, the volume of measurement cell 3 in this case is approximately
The amount is as small as 85μ, and if the amount of the test solution S is greater than this, the cell constant will be constant regardless of the amount of the test solution S.

In the sheet-type conductivity meter having the above configuration, since the conductivity measuring electrodes 4A and 4B are provided on the bottom surface of the measuring cell 3 having a fixed shape, when the test liquid is filled into the measuring cell 3, Since the test liquid always has a constant shape and the shape of the measurement cell 3 is constant, the cell constant is always constant regardless of the amount of test liquid, and therefore conductivity measurements can be performed with good reproducibility. can. Needless to say, the amount of test solution is extremely small.

In the above embodiment, in order to form the conductivity measuring electrodes 4A, 4B on a sheet, the conductivity measuring electrodes 4A, 4B are formed on one surface of one substrate 5, and the conductivity measuring electrodes 4A, 4B are formed on the other surface. Although the lead parts 6A and 6B are formed, the invention is not limited to this. For example, the conductivity measurement electrodes 4A and 4B and the lead parts 6A and 6 are formed on one surface of one highly insulating substrate.
B may be formed, and another highly insulating substrate may be stacked on the electrode forming surface side of this substrate.

The present invention is not limited to the above embodiments,
It is possible to implement various modifications.

FIG. 3 shows a second embodiment of the invention, in which the measuring cell 3 is connected to the conductivity measuring electrode 4.
A cell body 3A in which cells A and 4B are formed, and a bulged cell portion 3B formed to bulge so as to communicate with this cell body 3A. According to this configuration, a test liquid or a cleaning liquid is injected. In this case, an instrument 11 such as a dropper can be inserted into the bulging cell portion 3B, and the conductivity measuring electrodes 4A, 4 plated with platinum black can be inserted into the bulging cell portion 3B.
There is no possibility of other objects hitting the surface of B, and cleaning can be particularly easily performed.

FIG. 4 shows a third embodiment of the present invention, and in this embodiment, similarly to the second embodiment, the measuring cell 3 includes a cell body 3A on which conductivity measuring electrodes 4A and 4B are formed; A bulging cell portion 3B' is formed so as to communicate with the cell body 3A, and a cover body 12 is provided to cover the entire cell body 3A, for example. In addition to the advantages of the second embodiment described above, there is an advantage that the measurement is not easily influenced by outside air. In addition, 13
is a hole for removing air bubbles in the measurement cell 3.

FIG. 5 shows a fourth embodiment of the present invention. In this embodiment, a cover body 14 is provided so as to cover only the conductivity measuring electrodes 4A and 4B of the measuring cell 3, which is formed into a rectangular shape in plan view. It is something that

FIG. 6 shows a fifth embodiment of the present invention. In this embodiment, a partition member 16 with communication holes 15, 15 formed therein is provided so as to roughly divide the measurement cell 3, which is formed into a rectangular shape in plan view, into two parts. According to this embodiment, the cell constant increases due to the communication holes 15, 15, and the conductivity measurement electrode 4 increases accordingly.
The areas of A and 4B can be increased.

FIG. 7 shows a sixth embodiment of the present invention. In this embodiment, a cover body 18 partially provided with an opening 17 is slidably provided on the top of the measuring cell 3, and this cover body 18 is It is biased by a spring member 19 so that the measurement cell 3 is always covered in a completely sealed state during measurement or when not in use. According to this configuration, evaporation of the test liquid can be completely prevented. The conductivity measurement electrode 4 can be used to conduct measurements reliably and when not in use.
It is possible to prevent dust from adhering to the surfaces of A and 4B, and to reliably protect the electrode surfaces.

Although each of the above-mentioned embodiments has two conductivity measuring electrodes, the present invention is not limited to this, and can also be applied to four conductivity measuring electrodes. It goes without saying that it can be done.

[Effect of idea]

As explained above, the sheet-type conductivity meter according to the present invention has a concave measuring cell with a minute capacitance in the measuring part, and a conductivity measuring electrode is provided on the bottom surface of this measuring cell, so that the conductivity can be measured. Conductivity measurements can be performed with good reproducibility without sacrificing the advantages of this type of sheet-type conductivity meter, such as the ability to measure conductivity with an extremely small amount of test liquid due to the fact that the measurement electrode is in the form of a sheet. be able to.

[Brief explanation of the drawing]

1 and 2 show a first embodiment of the present invention, in which FIG. 1 is a plan view of a sheet-type conductivity meter, and FIG. 2 is a longitudinal sectional view thereof. FIG. 3 is a perspective view of essential parts showing a second embodiment of the present invention. FIG. 4 is a perspective view of main parts showing a third embodiment of the present invention. FIG. 5 is a perspective view of main parts showing a fourth embodiment of the present invention. 6th
The figure is a perspective view of essential parts showing a fifth embodiment of the present invention. FIG. 7 is a longitudinal sectional view showing a fifth embodiment of the present invention. FIG. 8 is a diagram for explaining the problems of the prior art. 2...Measurement section, 3...Measurement cell, 4A, 4B...
...Conductivity measurement electrode.

Claims (1)

[Scope of utility model registration request] 1. A sheet-type conductivity meter, characterized in that a concave measuring cell with a minute capacity is formed in the measuring part, and a conductivity measuring electrode is provided on the bottom surface of the measuring cell.