JPH07248303A - Electrode-liquid property measuring instrument and method thereof - Google Patents

Abstract

PURPOSE:To improve the measuring accuracy of a liquid property by reducing any possible effect of capacity ingredients inherent in a liguid and impurities being contained in this liquid. CONSTITUTION:A first set measuring electrode is composed of both first and second electrodes 31 and 32, while a second set measuring electrode is composed of the second electrode 32 and a third electrode 33 different from the first electrode 31 in terms of thickness, and these electrodes 31 to 33 are brined, while voltage is impressed in space of each set between electrodes 31 and 32 as well as 32 and 33. Difference in each set output between these electrodes 31 and 32 as well as 32 and 33 is taken by a difference circuit 8, whereby any possible effect of capacity ingredients and impurities inherent in a saline solution is conceled, and the difference part is compared with the set value out of a setting part 10 by a comparator circuit 11, and thereby it is made up so as to impart an on-off output according to whether concentration of the saline solution is higher than the set one or not.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid property measuring device and a liquid property measuring method for measuring the property of a liquid such as the concentration of a solution and the degree of contamination of the liquid, and an electrode suitable for the measurement.

[0002]

2. Description of the Related Art When measuring the properties of a liquid, for example, the concentration of saline solution, the weight concentration of the saline solution and the electrical conductivity generally have the relationship shown in FIG. As is clear from FIG. 8, the electric conductivity in saline increases as the weight concentration increases.

A liquid property measuring device having a circuit configuration as shown in FIG. 9, that is, a pair of measuring electrodes 5 in a saline solution 5.
0, 51 are provided, and a power supply 52 is provided between both measurement electrodes 50, 51.
In the device in which a constant voltage V0 is applied from the measurement electrode 50, the electric conductivity shown in FIG. 8 is represented by the current value i flowing between the measurement electrodes 52.
By measuring the current value i flowing through the space, the weight concentration of the saline 5 can be measured with reference to FIG.

[0004]

As described above, in a device in which a measuring electrode is arranged in a liquid such as saline and a voltage is applied between the measuring electrodes to measure the property of the liquid, the measurement flowing between the measuring electrodes is performed. The level of the signal for use is very small. Therefore, if an attempt is made to detect a liquid property such as the weight concentration of saline based on such a minute measurement signal with such a device, even a very small capacitive component in the liquid or a slight amount of impurities will be detected. However, noise components due to these influences and signal level fluctuations cannot be ignored for accurate measurement.

This is a major factor that causes difficulty in accurately and easily measuring the properties of a liquid with this type of device. In particular, in the case where the concentration of saline solution as one of the properties of the liquid is high, such a problem is more prominent, and the measurement accuracy of the device is greatly lowered, and its reliability is poor. is there.

Therefore, it is an object of the present invention to reduce the influence of the capacitive component of a liquid and impurities contained therein so that the properties of the liquid can be accurately and easily measured, and the accuracy of the measurement can be improved. It is an object of the present invention to provide an electrode, a liquid property measuring device, and a measuring method for the electrode, which are capable of improving the temperature.

[0007]

In order to achieve the above-mentioned object, the present invention is constructed as follows.

That is, the liquid property measuring device of the present invention is
A voltage is applied between a plurality of sets of measurement electrodes arranged at intervals in the liquid whose properties are to be measured, and the measurement electrodes of each set, and this application generates a voltage between each set of measurement electrodes. Circuit means for measuring the property of the liquid by the difference between the electric signals.

The circuit means comprises a timer for intermittently applying a voltage between the measuring electrodes.

Further, the circuit means includes a difference circuit for obtaining a difference between electric signals generated between the measurement electrodes of each set, a comparison circuit for comparing the difference circuit output with a set value and giving a comparison output, and a comparison output for the comparison output. And an output circuit that responds to provide an on / off output.

Alternatively, the circuit means stores in advance a difference circuit for obtaining a difference between electric signals generated between the measurement electrodes of each set, and characteristic data indicating a relationship between a liquid property and an output of the difference circuit. And a liquid property calculation unit that calculates a liquid property based on the output of the difference circuit and the characteristic data.

Further, the liquid property measuring device has a display section for displaying the calculated liquid property.

The liquid property measuring device measures the concentration of saline solution.

The liquid property measuring device is provided in a water softening device that softens hard water with an ion exchange resin, and measures the concentration of saline solution that regenerates the ion exchange resin.

Further, the liquid property measuring device is provided with means for detecting the number of times of regeneration of the ion exchange resin.

The electrode of the present invention comprises a plurality of sets of electrodes, and at least one of the electrodes of each set has a surface area, a length and a diameter which are different from those of the other sets of electrodes. is there.

In the liquid property measuring method of the present invention, a plurality of sets of measuring electrodes are arranged in a liquid at intervals, and a voltage is applied between the measuring electrodes of each set, and by this application, the measuring electrodes of each set are applied. The property of the liquid is measured by the difference between the electric signals generated during the period.

[0018]

The liquid property measuring apparatus of the present invention comprises a plurality of sets of measuring electrodes arranged in the liquid, and circuit means for measuring the property of the liquid by the difference between the electric signals generated between the measuring electrodes of each set. Since it is equipped, it is possible to cancel the influence of the capacitive component of the liquid and the impurities contained in the liquid by taking the difference between the electric signals generated between the measurement electrodes of each set, and to measure the property with higher accuracy. Is possible.

Since the circuit means is provided with a timer for intermittently applying a voltage between the measuring electrodes, corrosion of the electrode due to a chemical reaction in the vicinity of the electrodes and a corrosion of the electrode due to a chemical reaction in the vicinity of the electrodes are caused as compared with the case where the voltage is constantly applied. Adhesion of an insulating material is reduced and measurement accuracy is improved, and the life of the measurement electrode can be extended.

The circuit means includes a difference circuit for obtaining a difference between electric signals generated between the measurement electrodes of each set, a comparison circuit for comparing the difference circuit output with a set value and giving a comparison output, and a response circuit for responding to the comparison output. Since it has an output circuit that provides an on / off output, when the measured liquid property deviates from a predetermined property corresponding to the set value, the on / off output gives an alarm or a predetermined property. It is possible to drive a load for returning.

The circuit means calculates a liquid property on the basis of a storage section in which characteristic data indicating the relationship between the liquid property and the output of the difference circuit is previously stored, and the obtained output of the difference circuit and the characteristic data. Since the liquid property calculating unit is provided, it is possible to continuously grasp changes in the liquid property.

Since the liquid property measuring device has a display section for displaying the calculated liquid property, the change in the liquid property can be visually confirmed.

The liquid property measuring device measures the concentration of saline solution. Since saline solution has a small amount of change in electric current per unit weight concentration at high concentration, it is included in the capacitive component and liquid contained in the liquid. Although the influence of the impurities generated is remarkable, the present invention makes it possible to eliminate the influence and measure the concentration with higher accuracy.

The liquid property measuring device is provided in a water softening device that softens hard water with an ion exchange resin and measures the concentration of saline solution that regenerates the ion exchange resin. Concentration can be controlled with high accuracy.

Further, since the liquid property measuring device is provided with means for detecting the number of times of regeneration of the ion exchange resin,
This makes it easy to know when to replace the ion exchange resin.

The electrode of the present invention comprises a plurality of sets of electrodes, and at least one of the electrodes of each set has a surface area, a length and a diameter which are different from those of the other sets of electrodes. Therefore, it is suitable as a measuring electrode of the liquid property measuring device and the liquid property measuring method of the present invention.

According to the liquid property measuring method of the present invention, a plurality of sets of measuring electrodes are arranged in a liquid at intervals, and a voltage is applied between the measuring electrodes of each set, and by this application, the measuring electrodes of each set are applied. Since the property of the liquid is measured by the difference between the electric signals generated respectively, the influence of the capacitive component of the liquid and the impurities contained in the liquid can be obtained by calculating the difference between the electric signals generated between the measurement electrodes of each set. It is possible to cancel, and it is possible to measure the property with higher accuracy.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram of a liquid property measuring apparatus according to an embodiment of the present invention, and FIG. 2 is a perspective view showing its appearance.

The liquid property measuring apparatus 1 of this embodiment measures the weight concentration of saline solution more than the preset measurement concentration.
For example, when it becomes low, the load 2 such as a warning buzzer is driven by the relay output.

This liquid property measuring apparatus 1 comprises first to third electrode rods 3 ₁ to ₃ 3 as two sets of measuring electrodes arranged at intervals in a saline solution to be measured, and electrodes of each set. Voltages of the same phase are applied between the rods 3 ₁ , 3 ₂ ; 3 ₂ , 3 ₃ , respectively, and by this application, the electrode rods 3 ₁ , 3 _{2 of} each set are applied.
The apparatus main body 4 is equipped with a circuit means for measuring the weight concentration of saline solution as will be described later by the difference between the electric signals generated between 3 ₂ and 3 ₃ .

In this embodiment, the first to first measuring electrodes are used.
Of the third electrode rods 3 ₁ and 3 ₃ , the first and second electrode rods 3 ₁ and 3
₂ constitutes the first set of measurement electrodes, and the second and third electrode rods 3 ₂ and 3 ₃ constitute the second set of measurement electrodes, and the second set
The electrode rod 3 ₂ is also used in each group. Each electrode rod 3 _{1 to} 3
_{Although 3} is cylindrical and has the same length, the first electrode rod 3 ₁ of the first set and the third electrode rod 3 _{3 of} the second set have different diameters.

Here, the principle of measuring the weight concentration of saline according to the present invention will be described.

In the circuit configuration shown in FIG. 9 described above, the electric resistance R generated between the measuring electrodes 50 and 51 is given by the following equation, where σ is the electric conductivity of the saline solution 5.

R = A / σ The constant A in the above equation is the thickness of the measuring electrodes 50 and 51,
It is determined by the length or shape,
The current value flowing between the measuring electrodes 50 and 51 is measured by the measuring electrode 5
It can be controlled by appropriately selecting the shape of 0, 51 and the like.

Therefore, in the present invention, as shown in FIG. 3, the weight concentration of the saline solution 5 is measured using the _first to _third electrode rods 3 ₁ to ₃ 3 constituting the above-mentioned two sets of measuring electrodes. I am trying to do it.

That is, the first to third electrode rods 3 _{1 to} 3 ₃ are
Voltages of the same phase are respectively applied from the power source 6 between the first and second electrode rods 3 ₁ and 3 _{2 and} between the second and third electrode rods 3 ₂ and 3 ₃ which are soaked in the saline solution 5 to form each set. Apply. At this time, the first
Since the electrode rod 3 ₁ and the third electrode rod 3 ₃ have different diameters as described above, the liquid resistance R1 generated between the _first and second electrode rods 3 ₁ , 3 ₂ and the second, second The liquid resistance R2 generated between the three electrode rods 3 ₂ and 3 ₃ is different from each other. Therefore, the current value i flowing through each of the current detection resistors r
1 and i2 also have different values.

FIG. 4 is a characteristic diagram showing the relationship between the current value (circuit current) and the weight concentration of the saline solution 5, which is line A.
Is the current value i1 flowing between the _first and second electrode rods 3 ₁ and 3 _2.
The line B shows the current value i2 flowing between the _second and third electrode rods 3 ₂ and 3 ₃ , respectively. Such current value i
The difference C between 1 and i2 is approximately proportional to the weight concentration of the salt solution 5 in the high concentration range of the salt solution 5. Therefore, by previously obtaining the characteristic data of FIG. 4 by an experiment, the weight concentration of the salt solution 5 can be measured by the difference C between the current values i1 and i2, and moreover, the two sets of the electrode rods 3 ₁ , 3 _2; 3 _2, 3 by taking the difference C of the current values i1, i2 between _3, it is possible to cancel the influence of impurities contained in the capacitance component and brine 5 included in the brine 5, measurement accuracy Will be improved. In FIG. 3, the resistance R3 generated between the first electrode rod 3 ₁ and the third electrode rod 3 ₃
Does not affect the measurement because the potentials at both ends are almost zero.

Referring again to FIG. 1, the first to third electrode rods 3 ₁ to ₃ 3 of the liquid property measuring device 1 of this embodiment are immersed in the saline solution to be measured.

The apparatus main body 4 includes a power source 6 for applying a voltage of the same phase between the electrode rods 3 ₁ , 3 ₂ ; 3 ₂ , 3 ₃ constituting each set, and an intermittent application of the voltage, for example, several A timer 7 for every minute and the electrode rods 3 ₁ , which make up each set,
3 ₂ ; a difference circuit 8 that obtains a difference between current values flowing between 3 ₂ and 3 ₃ , and an amplifier circuit 9 that amplifies the output of the difference circuit 8.
A comparison circuit 11 that compares the amplified output of the difference circuit 8 with a preset value set in the setting unit 10 and provides a comparison output.
And a relay output section 12 as an output circuit that gives an on / off output in response to the comparison output.

As shown in FIG. 2, the setting unit 10 comprises a volume 13 provided on the front panel of the apparatus main body, and by operating this volume 13, 10% is set.
It is possible to set the weight concentration of the saline solution in a plurality of steps from 1 to 16%, and the setting unit 10 outputs the difference shown in FIG. 4 corresponding to the set weight concentration of the saline solution.

The comparison circuit 11 compares the measured difference from the amplifier circuit 9 with the set difference from the setting unit 10. In this embodiment, when the measured difference is small, that is, the difference is measured. When the weight concentration is lower than the set weight concentration, the relay of the relay output unit 12 is turned on to drive the load 2 such as the warning buzzer, and the warning LED 14 and the relay of the front panel shown in FIG. The LED 15 indicating the ON operation is turned on.

Therefore, the warning allows the user to know that the weight concentration of the saline solution has fallen below the set weight concentration, and can take appropriate measures such as increasing the salt amount.

In this embodiment, since the voltage application to the electrode rods 3 _{1 to} 3 ₃ is intermittently performed by the timer 7, even when the measurement is performed for a long time, the electrode rods 3 3
Insulators adhere to the surface of _{1 to} 3 ₃ or rust generation due to oxidation of the electrode rods 3 _{1 to} 3 ₃ is suppressed, and highly accurate measurement can be performed, and the length of the electrode rods 3 ₁ to ₃ 3 can be increased. The life can be extended.

FIG. 5 is a block diagram of a liquid property measuring apparatus according to another embodiment of the present invention, and FIG. 6 is a perspective view showing its appearance.

In the liquid property measuring device 16 of this embodiment, the first to third electrode rods 3 ₁ to ₃ 3 as two sets of measuring electrodes for measuring the weight concentration of saline solution are used as in the above-mentioned embodiment. When,
A pair of fourth and fifth electrode rods 3 _{4 serving} as electrodes for measuring the number of times of regeneration for detecting the number of times of regeneration of the ion-exchange resin described later.
3 ₅ and a device main body 17 for applying a voltage between the electrode rods 3 ₁ , 3 ₂ ; 3 ₂ , 3 ₃ ; 3 ₄ , 3 ₅ and taking in the output thereof. The liquid property measuring device 16 of this embodiment is installed in the water softening device 18 shown in FIG. 7.

In the water softening device 18, hard water is supplied from the pipe 42 to the inner tank 20 filled with the ion exchange resin 19 to soften the water by ion exchange, and the soft water is pumped through the branch valve 22 via the branch valve 22. Is sent out of the device.

The ion exchange resin 19 loses its effect of ion exchange after being used for a certain period of time, so it is necessary to wash it with the salt solution 5, that is, to perform so-called regeneration.

Therefore, after being used for a certain period, the outer tank 23
The salt solution 5 in the inside is supplied to the inner tank 20 through the branch valve 22 by the pump 21 to regenerate the ion exchange resin 19, the salt solution 5 used for the regeneration is discarded, and the new salt solution 5 is replaced with the outer tank 2
Supply to 3. After such regeneration, the use is started again to convert hard water into soft water.

The ion-exchange resin 19 needs to be replaced when the above-mentioned regeneration is repeated several times, for example, five times.

The liquid property measuring device 16 of this embodiment measures the weight concentration of the salt solution 5 which regenerates the ion exchange resin 19 of the water softening device 18 and also indicates the number of regeneration times indicating the time of exchanging the ion exchange resin 19. To detect,
The same first to third electrode rods 3 ₁ to ₃ 3 for measuring the weight concentration of the saline 5 and the pair of fourth and fifth electrode rods 3 ₄ for detecting the number of times of regeneration. , 3 ₅ and the outer tank 23
It is fixedly installed so as to be immersed in the saline solution 5. In addition, the saline solution 5 in the outer tank 23 is regenerated for regeneration.
When fed to 0, brine 5 of the outer tub 23 is adapted to be positioned lower than the tip of the electrode rod 3 ₁ to 3 _5.

The first to third electrode rods 3 ₁ to ₃ 3 forming the two sets of measurement electrodes have the same structure as that of the above-mentioned embodiment.

The fourth and fifth electrode rods 3 ₄ for measuring the number of reproductions,
3 ₅ is a pair of columnar electrode rods, and these electrode rods 3 ₄ and 3 ₅ are used after the ion exchange resin 19 is regenerated.
The number of times that the saline solution newly supplied to 3 comes into contact with the tips of the electrode rods 3 ₄ and 3 ₅ is detected as the number of times of regeneration.

Referring again to FIG. 5, the device main body 17 is
A signal input unit 24 to which an output between the electrode rods 3 ₁ , 3 ₂ ; 3 ₂ , 3 ₃ ; 3 ₄ , 3 ₅ is given, and each electrode rod 3 ₁ , 3 ₂ ; 3 ₂ ,
3 _3; 3 _4, 3 a power supply unit 43 for applying a voltage between _5, an amplifier 25 for amplifying the output of the difference circuit described above which is provided in the signal input unit 24 (not shown), the amplification portion 25 Of the load of the warning buzzer or the like by the output of the comparing unit 27 that compares the output of the setting unit 26 with the output of the setting unit 26.
6, an output unit 30 for driving a warning LED 29 provided on the front panel of the device as shown in FIG. 6, and fourth and fifth electrode rods 3 ₄ , 3 ₅ for measuring the number of reproductions. Based on the output of the above, the water contact detection unit 31 that detects water contact due to the supply of new saline solution, the number of times of water contact, that is, the counting unit 32 that counts the number of times of replay, and the counted number of times of replay are shown. 6, an output unit 34 for displaying the display unit 33 provided on the front panel of the apparatus is provided.

As in the above-mentioned embodiment, the setting section 26 is composed of a volume 35 provided on the front panel of the apparatus as shown in FIG. 6, and by operating this volume 35, saline solution of a plurality of stages is prepared. Can be set, and the difference shown in FIG. 4 corresponding to the set salt water concentration is output.

The weight concentration of the saline solution in this example was measured by
Similar to the above-mentioned embodiment, each set of electrode rods 3 ₁ , 3 ₂ ; 3
The difference between the current values flowing between ₂ and 3 ₃ is amplified and compared with a preset value set in the setting unit 26. When the weight concentration is lower than the preset weight concentration, the relay of the output unit 30 is turned on to output a warning. Drives a load 28 such as a buzzer and outputs L for warning
The ED 29 is turned on.

On the other hand, the number of times of regeneration of the ion exchange resin 19 is
The water contact at the tips of the fourth and fifth electrode rods 3 ₄ and 3 ₅ accompanying the supply of new saline after regeneration was performed, and the output voltage between both electrode rods 3 ₄ and 3 _{5 was} changed rapidly. Is detected by the water contact detection unit 31, the number of times is counted by the counting unit 32, and the display unit 3
Display in 3.

Therefore, when the weight concentration of the salt solution 5 falls below the set concentration, for example, the concentration required for the regeneration of the ion exchange resin 19, the user is warned by the LED for warning.
29, a warning buzzer or the like can be used to know this, and salt can be replenished to restore the desired concentration, and the number of times the ion exchange resin 19 has been regenerated is displayed on the display unit 33 on the front of the device. Therefore, the user can visually confirm the number of times of regeneration at any time, and when the number of times of regeneration reaches a predetermined number, for example, 5 times, it is possible to know that it is time to replace the ion exchange resin 19. Note that the number of times of reproduction is the reset switch 40 shown in FIG.
It is reset by operating.

In each of the above-mentioned embodiments, the second electrode rod 3 ₂ for measuring the concentration of the salt solution 5 is also used in each set, but as another embodiment of the present invention, the electrode is not used in combination. Additional bars may be added.

In the above-mentioned respective embodiments, the diameters of the first electrode rod 3 ₁ and the third electrode rod 3 ₃ are made different, and the electrode rods 3 ₁ , 3 of each set are made different.
₂ ; Although a difference is caused in the current value flowing between 3 ₂ and 3 ₃ , as another embodiment of the present invention, in place of the diameter, the length,
The surface area or shape, or a combination thereof, may cause a difference in current value flowing between the electrode rods of each set.

In each of the above embodiments, the measured saline solution 5
Although the on-off output is given by comparing the density of the above with the set density, as another embodiment of the present invention,
The characteristic data indicating the relationship between the concentration of the saline solution and the difference shown in FIG. 4 described above may be stored in advance, and the concentration of the saline solution may be calculated from the measured difference using the characteristic data. Further, the calculated concentration may be displayed on the display unit.

Although two sets of measurement electrodes are provided in each of the above-mentioned embodiments, the present invention is not limited to two sets, and more sets of measurement electrodes are provided and based on the difference between them. , May be measured.

Although the above embodiment has been described by applying it to the measurement of the concentration of saline solution, the present invention measures the concentration of other solutions, and further measures other properties of the liquid such as the degree of contamination of the liquid. Can also be applied to.

[0064]

As described above, according to the present invention, a circuit for measuring the property of a liquid by a plurality of sets of measuring electrodes arranged in the liquid and the difference between the electric signals generated between the measuring electrodes of each set. Since it is provided with a means, it is possible to cancel the influence of the capacitive component of the liquid and the impurities contained in the liquid by taking the difference between the electric signals generated between the measurement electrodes of each set, and with higher accuracy. It becomes possible to measure properties.

By intermittently applying the voltage between the measuring electrodes, the corrosion of the electrodes and the adhesion of the insulating material due to the chemical reaction in the vicinity of the electrodes are reduced as compared with the case where the voltage is constantly applied. The measurement accuracy can be increased and the life of the measurement electrode can be extended.

By equipping the liquid property measuring device of the present invention with a water softening device for converting hard water into soft water by means of an ion exchange resin, the concentration of saline solution for regenerating the ion exchange resin can be controlled with high accuracy. .

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is an external perspective view of the embodiment of FIG.

FIG. 3 is a diagram for explaining the measurement principle of the present invention.

FIG. 4 is a characteristic diagram showing the relationship between the weight concentration of saline solution and the circuit current.

FIG. 5 is a block diagram of another embodiment of the present invention.

6 is an external perspective view of the embodiment of FIG.

FIG. 7 is a configuration diagram of a water softening device.

FIG. 8 is a characteristic diagram showing the relationship between the weight concentration of saline solution and the electrical conductivity.

FIG. 9 is a configuration diagram of a conventional example.

[Explanation of symbols]

3 _{1 to} 3 ₅ 1st to 5th electrode rod 7 timer 8 difference circuit 10 setting unit 11 comparison circuit 12 relay output unit 13 volume 18 water softener

Claims (15)

[Claims] 1. A voltage is applied between a plurality of sets of measuring electrodes arranged at intervals in a liquid whose properties are to be measured, and the measuring electrodes of each set are measured by the application of the voltage. A liquid property measuring device, comprising: a circuit means for measuring the property of the liquid based on a difference between electric signals generated between the electrodes. 2. The liquid property measuring apparatus according to claim 1, wherein at least one of the measurement electrodes of each set has a diameter different from that of the measurement electrodes of the other sets. 3. The liquid property measuring apparatus according to claim 1, wherein the surface area of at least one of the measurement electrodes of each set is different from that of the measurement electrodes of the other sets. 4. The liquid property measuring apparatus according to claim 1, wherein at least one of the measurement electrodes of each set has a length different from that of the measurement electrodes of the other sets. 5. The circuit means comprises a timer for intermittently applying a voltage between the measuring electrodes.
Item 2. A liquid property measuring device according to any one of items. 6. The circuit means includes a difference circuit for obtaining a difference between electric signals generated between the measurement electrodes of each set, a comparison circuit for comparing the difference circuit output with a set value and giving a comparison output, and a comparison output. The liquid property measuring device according to any one of claims 1 to 5, further comprising an output circuit that responds to provide an on / off output. 7. The circuit means stores, in advance, a difference circuit for obtaining a difference between electric signals generated between the measurement electrodes of each set, and characteristic data indicating a relationship between a liquid property and an output of the difference circuit. The liquid property measuring device according to claim 1, further comprising: a unit, and a liquid property calculation unit that calculates a liquid property based on the output of the difference circuit and the characteristic data. 8. The liquid property measuring apparatus according to claim 1, wherein the property of the liquid is the concentration of saline solution. 9. The liquid property measuring apparatus according to claim 7, further comprising a display unit that displays the calculated liquid property. 10. The water softening device for softening hard water with an ion exchange resin, which is provided in the water softening device, wherein the property of the liquid is a concentration of a saline solution for regenerating the ion exchange resin. The liquid property measuring device according to any one of 1. 11. The liquid property measuring apparatus according to claim 10, further comprising means for detecting the number of times of regeneration of the ion exchange resin. 12. The liquid property measuring device according to claim 6, further comprising a volume for setting the set value, the volume being provided on a front surface of a panel of the liquid property detecting device. 13. The liquid property measuring device according to claim 9, wherein the display unit is provided on a panel front surface of the liquid property detecting device. 14. An electrode comprising a plurality of sets of electrodes, wherein at least one of the electrodes of each set is different from other sets of electrodes in at least one of surface area, length and diameter. . 15. An electric signal generated by arranging a plurality of sets of measuring electrodes at intervals in a liquid, applying a voltage between the measuring electrodes of each set, and generating a voltage between the measuring electrodes of each set by this application. The liquid property measuring method, characterized in that the property of the liquid is measured by the difference of