JPH0688803A - Electrode type ion concentration meter - Google Patents

Abstract

PURPOSE:To simultaneously measure ion concentrations in a plurality of channels by using various of measuring electrode sections. CONSTITUTION:The ion concentration of a solution to be inspected is measured by dipping measuring electrode sections in the solution and measuring the potential differences between ion electrodes and reference electrodes respectively constituting the measuring electrode sections with differential amplifiers. The title meter is equipped with differential amplifiers 10-40 which are provided by the number corresponding to a plurality of channels and respectively provided with input terminals W1-W4 for connecting ion electrodes, input terminals R1-R for connecting reference electrodes, and input/output terminals O1-O4 for connecting earthing electrodes, first switching means Ry2, S2, S31, and S32 which connect/separate the reference electrodes to/from each other, second switching means Ry1, S11, S12, S13, and S14 which connect/separate the input terminals for connecting reference electrodes and the common earthing potential point of the differential amplifiers, and control circuits of each switching means. The first switching means are used by the reference electrodes in a shared state in a differential mode and the second switching means are used in a non- differential mode.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode-type ion concentration meter such as a desk-top pH meter and an ion-selective electrode type analyzer, and more particularly to an electrode-type ion concentration meter capable of simultaneously measuring a plurality of channels.

[0002]

2. Description of the Related Art In this type of ion concentration meter, the pH value and other ion concentrations in the same test solution can be measured at the same time, and the same kind of test solution can be used for a plurality of kinds of test solutions. When measuring the ion concentration at the same time, it is necessary to provide a plurality of channels of measurement electrode portions including ion electrodes (ion-selective electrodes) such as glass electrodes and comparison electrodes. In this case, if a plurality of channels are measured by an amplifier that uses the reference electrode as the common potential of the circuit among the measurement electrode portions of each channel, the difference in the generated potential of each reference electrode and the difference in the output impedance affect the other channels, In some cases, the potential difference between the reference electrodes of each channel is generated, and the potential difference between the ion electrode and the reference electrode cannot be accurately measured.

In order to solve the above-mentioned inconvenience, a method is provided in which an insulating amplifier is provided for each channel as in industrial pH meters, and the potential between the ion electrode and the reference electrode is measured via these insulating amplifiers. However, according to this method, since an isolation amplifier is required for each measurement channel, there is a problem that the circuit configuration becomes complicated and the cost is increased.

On the other hand, there is also known a method in which an amplifier for amplifying the output voltage of the measurement electrode portion is provided for only one channel, and the measurement electrodes of a plurality of channels are sequentially switched and connected so that only one channel is constantly measured. However, this method has a drawback that simultaneous measurement of a plurality of channels is impossible, and it takes a long time to measure all of the plurality of channels.

Therefore, in order to perform simultaneous measurement on a plurality of channels without using an isolation amplifier, for example, an actual flat panel 3-10
A method of measuring by using a differential amplifier for each channel such as that disclosed in Japanese Patent No. 254 and Japanese Utility Model Laid-Open No. 50-124346 is effective. However, in this case, the measurement electrode unit connected to the differential amplifier of each channel must be provided with a ground electrode serving as a reference of these potentials in addition to the ion electrode and the reference electrode, Depending on the type of the measuring electrode unit that the user has, there may be a problem that the measuring electrode unit cannot be used as it is.

The present invention has been made in order to solve the above problems, and an object of the present invention is to provide various connection modes on the input side of differential amplifiers for a plurality of channels depending on the configuration of the measuring electrode section. An object is to provide an electrode-type ion densitometer that can be changed and has improved versatility and usability for simultaneous measurement of a plurality of channels.

[0007]

To achieve the above object, the present invention provides an input terminal for connecting a glass electrode or other ion electrode, an input terminal for connecting a reference electrode, an input terminal for connecting a ground electrode and an output. A differential amplifier having terminals is provided for a plurality of channels, and in the first invention, a switch means for connecting / disconnecting a plurality of input terminals for connecting reference electrodes is provided, and in the second invention, a comparison means is provided. Connects multiple input terminals for electrode connection to the ground potential point common to each differential amplifier /
It is provided with a switch means for separating and a control circuit such as a microcomputer for operating these switch means. Here, each of the switch means is composed of, for example, a relay and its contacts.

By combining the first and second inventions, first switch means for connecting / disconnecting a plurality of input terminals for connecting reference electrodes and a plurality of inputs for connecting reference electrodes. Both the terminals and the second switch means for connecting / disconnecting the ground potential point common to each differential amplifier may be provided together with these control circuits.

[0009]

According to the first aspect of the present invention, the input terminals for connecting the reference electrodes of the respective channels are separated or connected to each other by the switch means according to the structure of the measuring electrode section connected to the respective channels. This realizes a connection state equivalent to that all measurement electrode units have a reference electrode and a ground electrode, and the potential difference between the ion electrode and the ground electrode and between the reference electrode and the ground electrode is transferred to the differential amplifier for each channel. Ion concentration of multiple channels is measured simultaneously by capturing and differential mode. Therefore, it becomes possible to share the reference electrode of the measurement electrode section of an arbitrary channel with another channel. In the second aspect of the present invention, by connecting the input terminal for connecting the reference electrode of each channel and the ground potential point by the switch means, it is possible to simultaneously measure the ion concentration in each channel in the non-differential mode. You can

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram showing the main part of the electrode type ion concentration meter of this embodiment, which is constructed by combining the embodiments of the first and second inventions. In the figure, 10,
Reference numerals 20, 30, and 40 denote differential amplifiers corresponding to the first to fourth channels, and various measurement electrode portions of an electrode type ion concentration meter, such as a pH electrode, are connected to each channel. Here, the differential amplifiers 10-40 are operational amplifiers 11-13, 21-23, 31-33, 41-41, respectively.
43 and a plurality of resistors and capacitors. The power supply of each operational amplifier is not shown.

Next, the structure of the differential amplifier will be briefly described.
Since the configurations of the differential amplifiers 10 to 40 are the same, the differential amplifier 10 of the first channel will be described below as an example. The non-inverting input terminal of the operational amplifier 11 is connected to a first input terminal W ₁ via the resistor r _1, r _2, common resistor r _1, the connection point of r ₂ is the ground potential via the capacitor C ₁ (circuit Potential) point. A feedback resistor r ₃ is connected between the output terminal and the inverting input terminal of the operational amplifier 11.
The output terminal of the operational amplifier 11 is connected to the inverting input terminal of the operational amplifier 13 having the feedback resistance r ₉ via the resistance r ₄ .

On the other hand, the non-inverting input terminal of the operational amplifier 12 is connected to the second input terminal R ₁ via resistors r ₅ and r ₆ ,
The connection point of the resistors r ₅ and r ₆ is connected to the ground potential point via the capacitor C ₂ . A feedback resistor r ₇ is connected between the output terminal and the inverting input terminal of the operational amplifier 12. Further, the output terminal of the operational amplifier 12 is connected to the non-inverting input terminal of the operational amplifier 13 via the resistance r ₈ , and this non-inverting input terminal is connected to the ground potential point via the resistance r ₁₀ and the operational amplifier 13 The output terminal is connected to the output terminal O ₁ via the resistor r ₁₁ . Note that one end of the resistor r ₁₁ is connected to the ground potential point via the capacitor C ₃ . With the above configuration, the final operational amplifier 13 outputs a voltage proportional to the difference between the output voltages of the first operational amplifiers 11 and 12.

Similarly, the differential amplifiers 20 to 40 of the second to fourth channels are constructed in the same manner as described below.
30 and 40 have first and second input terminals W ₂ ,
And _{R 2, W 3, R 3} , W 4, R 4, and an output terminal O _2, O _3, O ₄ is connected. Although not shown, a multiplexer and an A / D are provided at the subsequent stage of the output terminals O ₁ , O ₂ , O ₃ , and O _4.
The converter and the microcomputer are sequentially connected, and the output signals from the output terminals O ₁ , O ₂ , O ₃ , and O ₄ are sequentially taken into the A / D converter by the multiplexer at a constant cycle and converted into digital signals. A microcomputer executes calculation of pH value and various ion concentrations. here,
By shortening the cycle of scanning the output signal through the multiplexer, the output signal of each channel, that is, the ion concentration can be simultaneously measured in almost real time. Of course, an A / D converter may be provided for each channel.

The second input terminals R ₁ , R _{2 of} each channel,
The contacts S ₁₁ , S ₁₂ , S ₁₃ , S _{14 of} the relay Ry ₁ shown in the lower part of FIG. 1 are connected to R ₃ , R ₄ , and these contacts S ₁₁ , S ₁₂ , S ₁₃ , The input terminals R ₁ , R ₂ , R ₃ , R ₄ and the ground potential point are connected / isolated by turning on / off S ₁₄ . In addition, the second input terminal R ₁ ,
Contact S ₂ of the relay Ry ₂ between R ₂ is likewise R _2,
The contacts S ₃₁ and S ₃₂ of the relay Ry ₃ are connected between R ₃ and R ₄ , respectively, and the input terminals R ₁ and R ₂ are connected / disconnected by turning on / off the contact S ₂ . Contact points S ₃₁ , S ₃₂
The input terminals R ₂ , R ₃ and R ₄ are connected / disconnected by turning on / off.

Here, the relay Ry ₂ and its contact S _{2 and the} relay Ry ₃ and its contacts S ₃₁ and S ₃₂ connect / separate the input terminals R _{1 to} R ₄ for connecting reference electrodes. grounding switch means to configure the relay Ry ₁ and its contacts _{S 11, S 12, S 13} , S 14 includes an input terminal R ₁ to R ₄ of the comparative electrode connected in common to the differential amplifiers 10-40 A second switch means for connecting / disconnecting the potential point is configured. The relays Ry _{1 to} Ry ₃ are operated by a control signal applied from a control circuit in the microcomputer via a gate circuit. The first and second
The switch means may be an analog switch such as an FET whose opening and closing is controlled by an analog control circuit.

In the present embodiment constructed as described above, for example, a pH electrode is connected to the first channel as a measurement electrode section, and measurement electrode sections for measuring other ion concentrations are provided in the second to fourth channels. The operation will be described as being connected. The correspondence between the channels and the types of measurement electrode parts is not particularly limited to this embodiment. When connecting the measurement electrode section, an ion electrode (ion-selective electrode) forming each measurement electrode section is connected to the first input terminals W ₁ , W ₂ , W ₃ , and W ₄ of each channel to connect each channel. A reference electrode is connected to at least one of the second input terminals R ₁ , R ₂ , R ₃ and R ₄ . Further, each channel is provided with an input terminal to which a ground electrode forming the measurement electrode portion is connected, and these input terminals are connected to a ground potential point.

Hereinafter, an example of connection between each channel and the measuring electrode portion will be described with reference to FIGS. 2 to 10. First, FIGS. 2 to 4 show the case where a pH electrode is connected to the first channel as the measurement electrode unit 100. Measurement electrode part 1
00 is an ion electrode (glass electrode) 101 and a reference electrode 10
2 and the ground electrode 103, and is usually of a composite type.

In FIG. 2, measurement electrode units 200A, 300A and 400A for measuring ion concentrations other than pH are connected to the other second to fourth channels, respectively. These measurement electrode units 200A, 300A, 40
Reference numeral 0A is composed of ion electrodes 201, 301, 401 and comparison electrodes 202, 302, 402, all of which are normally unipotential electrodes. The connection example of FIG. 2 can be realized by opening all the contacts S ₁₁ , S ₁₂ , S ₁₃ , S ₁₄ , S ₂ , S ₃₁ , S ₃₂ in FIG. In this state, the ground electrode 103 of the first channel is shared by the other second to fourth channels, so that the measurement electrode units 200A, 300A, 400.
It is equivalent to each A having a ground electrode.

According to this connection example, for the pH value, the measuring electrode unit 100 is used, and for other ion concentrations, the measuring electrode unit 200A, 300A, which does not have a ground electrode, is used.
With 400A, both can be measured simultaneously in differential mode. Although the figure shows the case where one type of test liquid a is measured in four channels, different types of test liquid are measured for each channel, or two types or one type are used for each channel. It is also possible to measure with a combination of three types.

In FIG. 3, the measurement electrode section 100 is used for the first channel, and the measurement electrode sections 200B, 300B, 400B composed of only the ion electrodes 201, 301, 401 are used for the other second to fourth channels, respectively. This is an example of connection. In this connection example, the contacts S ₂ , S ₃₁ , S in FIG.
By closing ₃₂ and opening contacts S ₁₁ , S ₁₂ , S ₁₃ , and S ₁₄ , the reference electrode 102 and the ground electrode 103 of the first channel are shared by the other second to fourth channels. Therefore, the measurement electrode units 200B, 300B, 400
B is equivalent to having a reference electrode and a ground electrode, respectively.

According to this connection example, the measuring electrode unit 100 for the pH value and the measuring electrode units 200B, 30 without the reference electrode and the ground electrode for the other ion concentrations.
Both 0B and 400B enable simultaneous measurement in the differential mode. In this example as well, various combinations are possible for the correspondence between each channel and the type of test liquid.

In FIG. 4, the measurement electrode section 100 is used for the first channel, and the measurement electrode section 200A including the ion electrode 201 and the reference electrode 202 is used for the second channel.
The third and fourth channels have ion electrodes 301, respectively.
This is an example in which the measurement electrode units 300B and 400B composed of only 401 are connected. In this connection example, the contact S in FIG.
₂ is opened, contacts S ₃₁ , S ₃₂ are closed, and contacts S ₁₁ ,
By opening S ₁₂ , S ₁₃ , and S ₁₄ , the reference electrode 202 of the second channel is shared by the third and fourth channels, and
The ground electrode 103 of the channel is shared by the other second to fourth channels. As a result, the measurement electrode unit 200A,
300B and 400B each have a ground electrode, and
The measurement electrode units 300B and 400B are equivalent to having a reference electrode as well.

According to this connection example, for the pH value, the measuring electrode unit 100 is used, and for other ion concentrations, the measuring electrode unit 200A having no ground electrode and the measuring electrode unit 300B having no reference electrode and no ground electrode are used. , 400B, both can be simultaneously measured in the differential mode.
In this example as well, various combinations are possible for the correspondence between each channel and the type of test liquid.

Next, in FIGS. 5 to 7, an ion electrode (glass electrode) 101 and a reference electrode 102 are provided in the first channel.
Is an example in which a pH electrode is connected as the measuring electrode unit 100A consisting of, and all of these connection examples assume measurement in a non-differential mode (normal mode). First,
The connection example of FIG. 5 is the contact points S ₁₁ , S ₁₂ , S ₁₃ ,
Close S _14, by opening the contact _{S 2, S 31, S 32} ,
It is realized by connecting all the input terminals for the reference electrodes of each channel to the ground potential point. In this connection example, the measurement electrode portion 100A having no ground electrode is used to p
It is effective when measuring the H value or when measuring one type of ion concentration other than the pH value.

In FIG. 6, the measurement electrode section 100A is connected to the first channel, and the ion electrodes 201, 301 and 401 and the comparison electrode 202, are connected to the second to fourth channels, respectively.
Measurement electrode unit 200A, 300 including 302, 402
A, 400A are connected and contact points S ₁₁ , S ₁₂ ,
S ₁₃ , S ₁₄ , S ₂ , S ₃₁ , and S ₃₂ are opened and closed in the same manner as in FIG.
2, 402 are all connected to the ground potential point.
In this connection example, different types of test liquids a to d are measured for each channel, and the pH values of the test liquids a to d and various types are measured by the measurement electrode units 100A, 200A, 300A, and 400A having no ground electrode. It is suitable for simultaneously measuring ion concentration.

Particularly in this example, since the test liquids a to d are insulated from each other, there is no need to perform measurement in the differential mode, and the relay Ry ₁ and its contacts S ₁₁ , S ₁₂ , S ₁₃ , S. ₁₄
By unifying the potentials of the reference electrodes of all channels to the ground potential, the simultaneous measurement in non-differential mode is enabled. In this connection example, one type of test liquid is used as the measurement target, and the pH is measured by the measurement electrode unit 100A.
The value is measured, and the other measurement electrode units 200A, 300A, 40
You may measure ion concentration other than pH value by 0A.

In FIG. 7, the measurement electrode section 100A is connected to the first channel, and the measurement electrode sections 200B, 300B and 400B consisting of only the ion electrodes 201, 301 and 401 are connected to the second to fourth channels, respectively. , Contacts S ₁₁ , S ₁₂ , S ₁₃ , S ₁₄ , S ₂ , S ₃₁ , S ₃₂ in FIG.
All the input terminals for the reference electrodes of each channel are connected to the ground potential point in the same open / close state as in FIG.
This connection example shows one type of test liquid a for each channel.
Is measured and the pH is measured by the measuring electrode unit 100A.
The value is measured, and the other measurement electrode units 200B, 300B, 40
It is suitable for simultaneously measuring ion concentrations other than the pH value by 0B. In the connection examples of FIGS. 6 and 7, various combinations can be made for the correspondence between each channel and the type of test liquid.

8 to 10 show connection examples in the case of measuring the pH value and various ion concentrations in the differential mode using the measurement electrode section having the ion electrode, the reference electrode and the ground electrode. Of these, FIG. 8 shows a measurement electrode unit 1 having an ion electrode 101, a reference electrode 102, and a ground electrode 103.
The pH of 00 is used for the pH of one test liquid a.
This is an example of connection for measuring a value, which is realized by opening all the contacts S ₁₁ , S ₁₂ , S ₁₃ , S ₁₄ , S ₂ , S ₃₁ , S ₃₂ in FIG. This connection example is for measuring electrode unit 1.
This is effective when measuring the pH value of one type of test liquid a by using 00, or when measuring the ion concentration of one type other than the pH value in the differential mode.

FIG. 9 shows that all the measuring electrode parts 100, 20
0, 300, 400 are ion electrodes 101, 20 respectively
1, 301, 401, reference electrodes 102, 202, 30
2, 402 and ground electrodes 103, 203, 303, 40
In the case of having No. 3, when different types of test liquids a to d are to be measured for each channel, FIG. 10 shows a case where one type of test liquid a is also to be measured. In these connection examples, the contacts S ₁₁ , S ₁₂ , S ₁₃ , S ₁₄ ,
This is realized by setting S ₂ , S ₃₁ , and S ₃₂ in the same open / close state as in FIGS. 8 and 2.

That is, FIG. 10 shows a measurement electrode unit 100, 200, 3 having an ion electrode, a reference electrode and a ground electrode.
00 and 400 are used to realize a connection example equivalent to FIG. 2, and FIG. 9 can be said to be applied to a plurality of types of test liquids a to d. That is, when the measurement electrode units 100, 200, 300, 400 shown in FIGS. 9 and 10 are used, the contacts S ₁₁ , S ₁₂ , S ₁₃ , S ₁₄ , S ₂ , S ₃₁ ,
By making the open / close state of S ₃₂ the same as in FIG. 2, it is possible to simultaneously measure the pH value and various ion concentrations in a differential mode for a plurality of channels. Here, FIG. 9 and FIG.
Also in the connection example of 1, various combinations can be made for the correspondence between each channel and the type of the test liquid.

[0031] As described above, according to this embodiment, the contact S ₁₁ depending on the configuration of the measuring electrode portion which is provided on the user _{side, S 12, S 13, S} 14, S 2, S 31, S 32 By changing the open / closed state, it is possible to simultaneously measure the ion concentrations of a plurality of channels in the differential mode or the non-differential mode. Especially when measuring in differential mode,
As shown in FIGS. 2 to 4, since the measurement electrodes of the second to fourth channels can be used without a ground electrode or a reference electrode, the versatility of the ion concentration meter is enhanced and the user side is easy to use. Is also good. Also, the user can use a relatively inexpensive measuring electrode unit.

Furthermore, in the above-mentioned embodiment, the connection example at the time of measurement has been mainly described, but the present invention can be applied to the case of calibrating the standard solution of the measuring electrode section, and the different standard solutions of different measuring electrode sections can be used. , Or if there is one that can be commonly used depending on the ion species to be measured, a common standard solution may be used to select each of the connection examples described above.

11 to 14 are display examples of the respective connection examples by the digital display portion provided in the ion concentration meter of this embodiment. In FIG. 11, CH indicates a channel display portion, RC indicates a connection state display portion of a comparison electrode, EC indicates a connection state display portion of a ground electrode, and MD indicates a mode display portion. FIG. 11 corresponds to the connection example of FIG. 8, FIG. 9, FIG. 10 or FIG. 2, in which the reference electrode of each channel is separated from the ground electrode and the ground electrodes of all channels are connected to each other. Equivalent states are displayed in the connection state display sections RC and EC
Is indicated by. On the mode display portion MD, the number "1" indicating that this mode is the first mode as the differential mode is displayed blinking.

FIG. 12 corresponds to the connection example of FIG. 3, and the connection state is equivalent to the state where the reference electrodes of all channels are connected to each other and the ground electrodes of all channels are connected to each other. This is indicated by the display parts RC and EC. On the mode display portion MD, the number "2" indicating that this mode is the second mode as the differential mode is displayed in blinking.

FIG. 13 corresponds to the connection example of FIG. 4, and is equivalent to the comparison electrodes of the second to fourth channels being connected to each other and the ground electrodes of all channels being connected to each other. The state is shown by the connection state display sections RC and EC. On the mode display portion MD, the number "3" indicating that this mode is the third mode as the differential mode is displayed in blinking.

FIG. 14 corresponds to the connection example of FIG. 5, FIG. 6 or FIG. 7, in which the reference electrodes and the ground electrodes of all channels are connected to each other, and the ground electrodes of all channels are connected to each other. Connected status display section R is equivalent to
It is shown by C and EC. On the mode display portion MD, the number "4" indicating that this mode is the fourth mode as the non-differential mode is displayed in blinking.

Since these display examples correspond to the connection examples of the respective electrodes, other various displays according to the connection examples are possible. For example, although illustration is omitted, when the reference electrodes are connected every two channels and the ground electrodes of all the channels are connected to each other, between the second and third channels in the connection state display portion RC of the reference electrode of FIG. You can remove the connection indication of. By performing the display as described above, the connection state of each measurement electrode portion can be immediately grasped visually, which is extremely convenient for the user.

The main purpose of the present invention is to enable the potential difference measurement in the differential mode or the non-differential mode by sharing the reference electrode and the ground electrode which constitute the measurement electrode section. Since the type and the measurement target are not particularly limited, the measurement is not limited to the electrode type ion concentration meter such as a pH meter, and the redox potential measurement or the measurement using the enzyme membrane electrode, etc.
It can be applied to various potentiometric measuring devices.

[0039]

As described above, according to the present invention, according to the configuration of the measurement electrode unit connected to each channel by the user,
In the first invention, the connection / separation between the reference electrode connection input terminals of an arbitrary channel is predetermined, and in the second invention, the connection / separation between the reference electrode connection input terminal of an arbitrary channel and the ground potential point is predetermined. It is realized by the switch means and the control circuit.

Therefore, if at least one measuring electrode portion has a reference electrode, each differential amplifier has a common ground potential point. Therefore, in the first aspect, the reference electrode is used for another channel. By sharing the same, it is possible to realize a connection state equivalent to that all the measurement electrode units have the comparison electrode and the ground electrode, and it is possible to simultaneously measure the ion concentration and the like in the differential mode for each channel. Further, according to the second invention, by connecting the input terminal for connecting the reference electrode of each channel to the ground potential point, it is possible to simultaneously measure a plurality of channels in the non-differential mode.

Therefore, the structure of the measuring electrode unit usable by the user is diversified, the degree of freedom of measurement is greatly improved, and the versatility, the usability, and the economical efficiency are improved.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a main part of an embodiment of the present invention.

FIG. 2 is a diagram showing a connection example of a measurement electrode unit in the example.

FIG. 3 is a diagram showing a connection example of the measurement electrode unit in the example.

FIG. 4 is a diagram showing a connection example of the measurement electrode unit in the example.

FIG. 5 is a diagram showing a connection example of the measurement electrode unit in the example.

FIG. 6 is a diagram showing a connection example of the measurement electrode unit in the example.

FIG. 7 is a diagram showing a connection example of the measurement electrode unit in the example.

FIG. 8 is a diagram showing a connection example of the measurement electrode unit in the example.

FIG. 9 is a diagram showing a connection example of the measurement electrode unit in the example.

FIG. 10 is a diagram showing a connection example of the measurement electrode unit in the example.

FIG. 11 is a diagram showing a display example of a connection example of the measurement electrode unit in the example.

FIG. 12 is a diagram showing a display example of a connection example of the measurement electrode unit in the example.

FIG. 13 is a diagram showing a display example of a connection example of the measurement electrode unit in the example.

FIG. 14 is a diagram showing a display example of a connection example of the measurement electrode unit in the example.

[Explanation of symbols]

10, 20, 30, 40 Differential amplifier 11, 12, 13, 21, 22, 23, 31, 32, 3
3, 41, 42, 43 operational amplifier 100, 100A, 200, 200A, 200B, 30
0,300A, 300B, 400,400A, 400B
Measurement electrode section 101, 201, 301, 401 Ion electrode 102, 202, 302, 402 Reference electrode 103, 203, 303, 403 Ground electrode W ₁ , R ₁ , W ₂ , R ₂ , W ₃ , R ₃ , W ₄ , R ₄ input terminal O ₁ , O ₂ , O ₃ , O ₄ output terminal Ry ₁ , Ry ₂ , Ry ₃ relay S ₁₁ , S ₁₂ , S ₁₃ , S ₁₄ , S ₂ , S ₃₁ , S ₃₂ contact

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Satoshi Ito 4-13-14 Kitacho, Kichijoji Kitamachi, Musashino-shi, Tokyo Electrochemical Instruments Co., Ltd.

Claims (2)

[Claims] 1. The ion concentration in the test solution is measured by immersing the measurement electrode section in the test solution and measuring the potential difference between the ion electrode and the reference electrode forming the measurement electrode section with a differential amplifier. The electrode type ion densitometer includes an input terminal for connecting an ion electrode, an input terminal for connecting a reference electrode, an input terminal for connecting a ground electrode, and a differential amplifier having a plurality of channels for an output terminal for a plurality of channels. An electrode type ion concentration meter, comprising: a switch means for connecting / disconnecting a plurality of input terminals for connection, and a control circuit for operating the switch means. 2. The ion concentration in the test solution is measured by immersing the measurement electrode section in the test solution and measuring the potential difference between the ion electrode and the reference electrode forming the measurement electrode section with a differential amplifier. The electrode type ion densitometer includes an input terminal for connecting an ion electrode, an input terminal for connecting a reference electrode, an input terminal for connecting a ground electrode, and a differential amplifier having a plurality of channels for an output terminal for a plurality of channels. An electrode type ion densitometer, comprising: switch means for connecting / disconnecting a connection input terminal and a ground potential point common to each differential amplifier; and a control circuit for operating the switch means.