Electricity: measuring and testing – Electrolyte properties – Using a conductivity determining device
Reexamination Certificate
2001-10-22
2004-02-10
Le, N. (Department: 2858)
Electricity: measuring and testing
Electrolyte properties
Using a conductivity determining device
C324S450000, C324S691000
Reexamination Certificate
active
06690172
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a multiple electric conductivity measuring apparatus having a plurality of electric conductivity measuring cells, and more specifically, relates to a multiple electric conductivity measuring apparatus capable of accurately measuring a difference or variation of the electric conductivities between measuring points different in position or time in a treatment system containing a substance to be measured such as an aqueous solution and the like.
BACKGROUND ART OF THE INVENTION
Electric conductivity is especially employed as a scale to measure a concentration of ions capable of migrating in an aqueous solution, and an electric conductivity measuring apparatus is used to measure ion concentrations in many kinds of aqueous solutions. An electric conductivity measuring apparatus, generally, determines an increase or a decrease of the ion concentration of an aqueous solution to be measured by measuring the resistance of the aqueous solution existing between an electric conductivity detection electrode and an electric current supply electrode connected to a power source.
As a method for using a conventional electric conductivity measuring apparatus, the electric conductivity measuring apparatus is installed at a predetermined measuring point, or a sample solution is introduced from a predetermined measuring point into the electric conductivity measuring apparatus, and the electric conductivity measured by the apparatus is utilized for observing the condition of an aqueous solution or controlling the water quality thereof and the like in many kinds of fields. In the measurement of electric conductivity by the electric conductivity measuring apparatus, usually, the measurement is conducted after adjusting the measuring range of the electric conductivity measuring apparatus in accordance with a condition of a substance to be measured, a condition of an electrode, a condition of the circumstances at the time of the measurement (for example, an ambient temperature or a condition of noises from surrounding equipment) and the like. Further, in this measurement, a surface condition of the electrode often varies with time since organic substances and the like contained in a substance to be measured onto the electrode of the electric conductivity measuring apparatus. In such a condition, a drift from a desired measuring standard point occurs more or less during the measurement. Therefore, the data of the electric conductivity measured by the electric conductivity measuring apparatus are deemed to be data which are relatively low in reliability as data used for operation management or control, and it is the present situation that the data are considered as secondary data.
Especially, in a case where measurement data of electric conductivity are collected from a plurality of measuring points, and, for example, a progress degree of a treatment of an aqueous solution between the plural measuring points, or a variation of water quality between these measurement points, and further, in a case where a variation of the electric conductivity with time is measured at a substantially identical measuring position, practically it is difficult to measure with a high accuracy, because the measuring range of each apparatus is adjusted, or a drift occurs with time, as described above. Further, when a variation of electric conductivity, or a difference in electric conductivities between a plurality of measuring points is to be measured, in a case where the variation or the difference is much smaller than the absolute value of the electric conductivity which is being measured, since the measuring range is adjusted relative to the relatively great absolute value of the electric conductivity, it is very difficult to distinguish such a micro variation or difference, or, the measured data become low in reliability. In practice, however, there are many requirements to measure such a micro difference or variation between two or a plurality of measuring points different in position or time. If such a micro difference or variation can be measured with a high reliability, a high accuracy and a high sensitivity, it is considered that the use is very broad. However, an electric conductivity measuring apparatus capable of satisfying such requirements has not yet been found.
DISCLOSURE OF THE INVENTION
Accordingly, it is an object of the present invention to provide a multiple electric conductivity measuring apparatus capable of measuring a micro difference or variation of electric conductivity between a plurality of measuring points different in position or time with a high reliability, a high accuracy and a high sensitivity to satisfy the above-described requirements.
To accomplish the above-described object, a multiple electric conductivity measuring apparatus according to the present invention comprises at least two electric conductivity measuring cells each having at least two electrodes brought into contact with a substance to be measured, the electric conductivity measuring cells are so connected electrically that sensing signals themselves from the electric conductivity measuring cells can be treated to be added and/or subtracted.
Namely, in a conventional electric conductivity measuring apparatus, a sensing signal from one electric conductivity measuring cell is amplified by an amplifier and the like, and the amplified signal is rectified into a signal with an appropriate level as an output signal for measuring an electric conductivity, and when a plurality of electric conductivity measuring apparatuses are installed, it has been necessary to adjust a measuring range for each electric conductivity measuring apparatus. In the multiple electric conductivity measuring apparatus according to the present invention, however, within the apparatus itself, an electrical calculation treatment such as addition, subtraction and the like is performed with respect to the sensing signals themselves sent from the respective electric conductivity measuring cells, and the signal after the treatment is amplified as needed, and is output as a difference or variation between the electric conductivities measured at the respective electric conductivity measuring cells. Therefore, the multiple electric conductivity measuring apparatus according to the present invention is basically and distinctly different from the conventional technology in that the conventional electric conductivity measuring apparatuses are merely disposed in plural form and a difference or variation between the data measured by the apparatuses is obtained.
In this multiple electric conductivity measuring apparatus according to the present invention, the above-described at least two electrodes in each electric conductivity measuring cell can be constructed from an electric conductivity detection electrode and an electric current supply electrode. The two-electrode formation itself as the constitution of the electrode is heretofore known. To the electric current supply electrode, for example, an AC current is supplied. In a case where a plurality of electric current supply electrodes are disposed, an amplified or attenuated AC current may be supplied to at least one electric current supply electrode. If an AC current is amplified before being supplied to an electric current supply electrode, it can create substantially the same condition that the supplied electric current is multiplied by a predetermined magnification, and the same effect of the multiplication can be obtained also on sensing signals sent from the electric conductivity measuring cells. If an AC current is attenuated before being supplied to an electric current supply electrode, it can create substantially the same condition that the supplied electric current is divided by a predetermined rate, and the same effect of the division can be obtained also on sensing signals sent from the electric conductivity measuring cells. If the sensing signals themselves thus created are added or subtracted, the multiplication or the division is included in t
Le N.
Nguyen Vincent Q.
Norris & McLaughlin & Marcus
Organo Corporation
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