JP2010127865A - Measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a measuring device in which its measuring section is attachable/removable to the device itself, with an extension cable connectable between both, while more accurate measurements can be obtained more easily, depending on the characteristics of the extension cable. <P>SOLUTION: The measuring device 1 includes the measuring section 20, having detection elements 21, 24 and its unique cable 22 connected to the detection elements, its body 10 with its measuring section attachably/detachably connected through the unique cable, and a transducer 11 for calculating measurements, based on the detected signal input from the detection elements into the body. In the device 1, an extension cable 30 to be connected with the detection elements can be connected between the measuring section and the body. The device includes conversion information providing means 12, which provides the conversion information for correlating the detected signal with the measurements, depending on properties of the extension cable to the transducer, and this transducer uses the conversion information, to calculate these measurements depending on the characteristics of the extension cable, based on the detected signal input from the detection elements connected with the device body via the extension cable. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  In the present invention, a measurement unit such as a temperature sensor, a pH sensor, an ion sensor, an ORP sensor, or an electrical conductivity sensor is detachable from the apparatus main body, and an extension cable is connected between the measurement unit and the apparatus main body. It is related with the measuring device which can be used.

  Conventionally, a temperature sensor using a resistance temperature detector is widely used as a temperature detection element. The resistance temperature detector has an electrical resistance value that changes depending on the temperature, and this can be used to measure the temperature. As the resistance temperature detector, a metal such as platinum, nickel, or copper, or a thermistor is used.

  In addition to being used alone, the temperature sensor is incorporated in a pH sensor, an ion sensor, an ORP sensor, an electrical conductivity sensor, or the like, and is used for temperature compensation based on a temperature measurement value.

  As a temperature sensor using a resistance temperature detector, a four-wire type sensor is widely used, and this prevents the electrical resistance value of the cable core (conductor) itself from affecting the measurement value of the temperature sensor. It has become.

  The 4-wire temperature sensor has a large number of cable cores, and the cross-sectional area of the cable may increase. In particular, for a measurement unit (probe) in which a temperature sensor is incorporated in a pH sensor or the like, the cross-sectional area of the cable becomes very large, which may cause problems in terms of space and operability. Therefore, it is conceivable to adopt a two-wire type with a reduced number of core wires instead of the four-wire type as a temperature sensor using a resistance temperature detector.

  Conventionally, it has been widely practiced to measure the electrical conductivity of a solution and to investigate, for example, the proportion of the electrolyte in the solution. In general, the electrical conductivity of a solution depends on the ions present in the solution and follows Ohm's law as well as metal conductors. In the case of a solution, the electrical resistance between two opposing faces of 1 m 3 is expressed as resistivity, and the reciprocal thereof is expressed in units of S / m as electrical conductivity. As a method for measuring the electrical conductivity, an electrical conductivity measurement electrode (electrical conductivity cell) including at least a pair of electrodes is immersed in the solution to be measured, and a voltage is applied between the electrodes to thereby measure the electrical conductivity of the solution to be measured. There is a so-called electrode method in which resistance is measured to determine electrical conductivity. More specifically, for example, a sine wave or rectangular wave AC voltage is applied between the electrodes of the electrical conductivity cell, and a current flowing between the electrodes is detected and converted into electrical conductivity.

  Even if the solute concentration of the solution is the same, the electrical conductivity of the solution varies with the temperature of the solution. Therefore, the electrical conductivity of the solution is generally displayed in terms of electrical conductivity at a reference temperature (usually 25 ° C.). The electric conductivity cell has various shapes and sizes depending on the purpose of use and the like, and a constant (cell constant) for conversion into electric conductivity is determined from the electrode area and the electrode interval. The cell constant is usually a value obtained by dividing the interelectrode distance by the electrode area.

  Since the cell constants of the electric conductivity cells usually have different values one by one, it is necessary to set the cell constants in advance in the apparatus when measuring the electric conductivity. Therefore, generally, the cell constant is obtained individually at the time of factory shipment of an electrical conductivity sensor having an electrical conductivity cell, and provided together with the electrical conductivity sensor. In this case, in order to facilitate the setting of the cell constant, the cell constant may be stored in a storage medium provided in the cable or connector of the electrical conductivity sensor (Patent Document 1).

  By the way, in the measuring apparatus in which the measuring unit is detachable from the apparatus main body, when the standard cable (unique cable) of the measuring unit for connecting the measuring unit to the apparatus main body is short in light of the measurement purpose, Furthermore, there is a case where an extension cable (extension cable) is connected between the measurement unit and the apparatus main body to increase the length of the entire cable.

  However, for example, in the case of a two-wire temperature sensor as described above, the measured value of the temperature sensor is affected by the electrical resistance value of the cable core. When the distance between the measuring unit and the main body of the device is short, there is often no problem, but when an extension cable is connected to the specific cable of the measuring unit, the electrical resistance value ( An error occurs in the measured value of the temperature sensor due to the resistance between the lines).

  When the electrical conductivity sensor can be attached to and detached from the device body as a measurement unit, the cell is usually individually included in the state including the electrical conductivity cell and the specific cable when the electrical conductivity sensor is shipped from the factory. A constant is determined (ie, the electrical resistance value of the cable core of the specific cable is also taken into account) and provided with the electrical conductivity sensor.

  However, as in the case of the temperature sensor, when an extension cable is further connected to the specific cable of the conductivity sensor, the electrical conductivity is measured by the electrical resistance value (interline resistance) of the core wire of the extension cable. An error occurs in the value.

  Therefore, conventionally, in order to obtain a more accurate measurement value when using an extension cable, the measurement value is calculated manually from the length of the extension cable or its core wire (hereinafter simply referred to as “the length of the cable”). It is going to correct.

  However, correction by manual calculation as described above is complicated and causes errors. In particular, in a measuring apparatus that can use a plurality of types of extension cables having different lengths, it is very cumbersome and erroneous to perform the correction by the above-described manual calculation according to the length of the extension cable. It becomes easy to generate.

  Patent Document 2 has a short-circuit switch that short-circuits both ends of the temperature measurement element in a conductivity meter having a detector having a measurement cell for measuring electrical conductivity and a temperature measurement element. The resistance value of the temperature measurement cable measured by short-circuiting both ends of the temperature measurement element is regarded as the resistance value of the conductivity measurement cable, and the resistance value of the conductivity measurement cable is subtracted from the resistance value at the time of conductivity measurement to obtain the solution resistance value. A method for obtaining and calculating the conductivity from the solution resistance value is disclosed.

  According to the method described in Patent Document 2, the electrical resistance values of the temperature measurement cable and the electrical conductivity measurement cable can be obtained, but this is not preferable because the apparatus configuration becomes complicated. Patent Document 2 does not disclose any extension cable.

In the above, the temperature measurement error due to the difference in the length of the extension cable has been explained, but the characteristics (cross-sectional area, etc.) related to the electrical resistance value per unit length of the extension cable core wire even if the length is the same The same can be said about the error due to the difference between the two or the error when both are different.
JP-A-10-253572 Japanese Patent Laid-Open No. 2003-66077

  The present invention has been made in view of the above-described problems, and in the measurement apparatus in which the measurement unit can be attached to and detached from the apparatus main body, and an extension cable can be connected between the measurement unit and the apparatus main body. It is an object of the present invention to provide a measuring device that can obtain a more accurate measurement value more easily and according to the characteristics of an extension cable.

  The above object is achieved by the measuring apparatus according to the present invention. In summary, the present invention provides a measurement unit having a detection element and a specific cable having a core wire connected to the detection element, and an apparatus main body to which the measurement unit is detachably connected by the specific cable; A transducer that is provided in the apparatus body and obtains a measurement value based on a detection signal that is input from the detection element to the apparatus body, and includes a core wire connected to the detection element An extension cable is connectable between the measurement unit and the apparatus main body, and provides conversion information for associating the detection signal with the measurement value to the converter according to characteristics of the extension cable. Based on the detection signal input from the detection element of the measurement unit connected to the apparatus main body via the extension cable using the conversion information. A measuring apparatus and obtaining the measurement value corresponding to the characteristics of the extension cable.

  According to an embodiment of the present invention, as the characteristic information providing means for providing the converter with characteristic information relating to the characteristics of the extension cable, the extension cable is provided with an extension cable side storage medium storing the characteristic information. It has been. According to another embodiment, as the characteristic information providing means for providing the converter with characteristic information relating to the characteristics of the extension cable, an input means for inputting the characteristic information by an operator is provided in the apparatus body. ing. According to another embodiment, as the characteristic information providing means for providing the converter with characteristic information relating to the characteristics of the extension cable, the extension cable includes a switch, an analog switch, a resistor, and a capacitor. A physical quantity or state changing means such as a voltage generator, a current generator, a light generator, etc .; a physical quantity generating means; a physical shape change; or an information presentation means selected from the group consisting of a bar code, The apparatus main body is further provided with a recognition unit for recognizing the characteristic information attached to the information presentation unit.

  According to an embodiment of the present invention, the conversion information providing means is a main body side storage medium included in the apparatus main body. According to a preferred embodiment, the conversion information is a value to be subtracted from the processing value according to the characteristics of the extension cable and the characteristics of the extension cable in the process of obtaining the measurement value from the detection signal by the converter. The converter obtains the measurement value obtained by subtracting the error corresponding to the characteristics of the extension cable based on the relationship. According to another preferred embodiment, the conversion information is information indicating a relationship between the detection signal and the measured value for each characteristic of the extension cable, and the converter is a characteristic of the extension cable. Accordingly, the measurement value is obtained by using information indicating the relationship between the detection signal and the measurement value according to the characteristics of the extension cable provided from the main body side storage medium.

  According to an embodiment of the present invention, the conversion information providing means is a measurement unit side storage medium included in the measurement unit. According to a preferred embodiment, the conversion information is a value to be subtracted from the processing value according to the characteristics of the extension cable and the characteristics of the extension cable in the process of obtaining the measurement value from the detection signal by the converter. The converter obtains the measurement value obtained by subtracting the error corresponding to the characteristics of the extension cable based on the relationship. According to another preferred embodiment, the conversion information is information indicating a relationship between the detection signal and the measured value for each characteristic of the extension cable, and the converter converts the characteristic of the extension cable into the characteristic of the extension cable. Accordingly, the measurement value is obtained using information indicating the relationship between the detection signal and the measurement value according to the characteristics of the extension cable provided from the measurement unit side storage medium.

  According to an embodiment of the present invention, the apparatus main body includes writing means for storing the conversion information in the measurement unit side storage medium.

  According to an embodiment of the present invention, the conversion information providing means is an extension cable side storage medium included in the extension cable. According to a preferred embodiment, the conversion information is a value to be subtracted from the processing value according to the characteristics of the extension cable and the characteristics of the extension cable in the process of obtaining the measurement value from the detection signal by the converter. The converter obtains the measurement value obtained by subtracting the error corresponding to the characteristics of the extension cable based on the relationship. According to another preferred embodiment, the conversion information is information indicating a relationship between the detection signal and the measurement value according to characteristics of the extension cable, and the converter stores the extension cable side memory. The measurement value is obtained using information indicating a relationship between the detection signal and the measurement value according to the characteristics of the extension cable provided from a medium.

  According to an embodiment of the present invention, the apparatus main body includes writing means for storing the conversion information in the extension cable side storage medium. According to an embodiment of the present invention, the apparatus main body includes a capturing unit that takes in the conversion information from an information transmission medium outside the apparatus main body. According to a preferred embodiment, (a) the information transmission medium is a removable storage medium that is detachably connected to the apparatus main body, and the capturing means is a reading means for reading information from the removable storage medium. Or (b) the information transmission medium is a communication means for communicatively connecting a device external to the apparatus main body and the apparatus main body, and the capturing means receives information transmitted via the communication means. It is a receiving means for receiving.

  According to an embodiment of the present invention, the apparatus main body includes conversion information input means for inputting the conversion information by an operator.

  According to an embodiment of the present invention, the characteristics of the extension cable include the extension cable or the length of the core wire in the extension cable and the electrical resistance value per unit length of the core wire in the extension cable. Or both. According to another embodiment of the present invention, the characteristic of the extension cable is an electrical resistance value of the core wire in the extension cable.

  According to the present invention, the measuring unit can be attached to and detached from the apparatus main body, and an extension cable can be connected between the measuring unit and the apparatus main body. More accurate measurements can be obtained.

  Hereinafter, the measuring apparatus according to the present invention will be described in more detail with reference to the drawings.

Example 1
1. Overall Configuration of Measuring Device FIG. 1 is a schematic block diagram showing an embodiment of a measuring device according to the present invention. In this embodiment, the measuring device 1 is an electric conductivity measuring device used for measuring the electric conductivity of a solution.

  In this embodiment, the measuring device 1 is configured to measure the electrical conductivity of the solution by an electrode method. The measuring apparatus 1 includes an apparatus main body 10, a temperature sensor, and an electrical conductivity measurement electrode (electrical conductivity cell) that are integrally combined, and a measuring unit (electrical conductivity sensor) that can be attached to and detached from the apparatus main body 10. 20, and an extension cable 30 can be connected between the measurement unit 20 and the apparatus main body 10.

  The apparatus main body 10 has a controller 11 (converter, signal processing means, control means) that comprehensively controls the operation of the measurement apparatus 1 and obtains a measurement value from the detection signal. Further, the apparatus main body 10 includes a main body side storage medium 12 for storing a predetermined program and data, connected to the controller 11, a main body side connector 13 for connecting the measuring unit 20, a power source for electric conductivity measurement and detection. Electrical conductivity detection circuit 14 provided with a signal amplification circuit, etc., temperature detection circuit 15 provided with a temperature measurement power source and a detection signal amplification circuit, etc., and the electrical conductivity or temperature detection signal is converted from analog to digital (A / Analog-to-digital converter (A / D converter) 16 that performs D conversion), display unit 17 that displays measurement values and various setting values, and the like, inputs instructions for starting or stopping measurement operations and calibration operations, or various setting values An operation unit 18 as input means is provided. The operation unit 18 is provided with keys for inputting data. The main body side connector 13 can be connected to the measuring unit 20 directly via its fixed cable (unique cable) 22 or via an extension cable 30. In addition, the apparatus main body 10 is provided with a power supply circuit and the like that are connected to an external power source and supply operating power to each part of the apparatus main body 10.

  The measurement unit 20 is for connecting the temperature sensor 21, the electrical conductivity cell 24 including a pair of electrodes (platinum black plating electrodes) 24 a and 24 b, and the temperature sensor 21 and the electrical conductivity cell 24 to the apparatus main body 10. A specific cable 22 having a corresponding core wire, and a measurement unit side connector 23 provided at an end of the specific cable 22 for detachably connecting the measurement unit 20 to the apparatus main body 10 or the extension cable 30. Have.

  The temperature sensor 21 uses a resistance temperature detector as a temperature detection element. In particular, in this embodiment, a thermistor is used as the resistance temperature detector. In addition, a metal such as platinum, nickel, or copper can be used as the resistance temperature detector as the temperature detecting element. In this embodiment, the temperature sensor 21 is a two-wire type.

  The extension cable 30 is a connection means for connecting the measurement unit 20 and the apparatus main body 10 so that communication such as a detection signal is possible when a long distance between the measurement unit 20 and the apparatus main body 10 is desired. It is used for the extension of The extension cable 30 has an extension cable body 31 having a corresponding core wire for connecting the temperature sensor 21 and the electrical conductivity cell 24 to the apparatus body 10 respectively. The extension cable 30 is provided at one end of the extension cable main body 31, and a first extension connector 32 for detachably connecting the extension cable 30 to the apparatus main body 10 and the other end of the extension cable main body 31. And a second extension connector 33 for detachably connecting the extension cable 30 to the measurement unit 20.

  As described above, in this embodiment, the measuring apparatus 1 includes a detection element (the thermistor of the temperature sensor 21, the electrical conductivity cell 24) and a core wire (conductive wire) formed of a conductor connected to the detection element. Based on a measurement unit 20 having a cable 22, a device main body 10 to which the measurement unit 20 is detachably connected by a unique cable 22, and a detection signal input to the device main body 10 from a detection element provided in the device main body 10. And a controller 11 as a converter for obtaining a temperature measurement value. Further, the measuring device 1 includes a core wire (conductive wire) formed of a conductor connected to the detection element (the thermistor of the temperature sensor 21, the electrical conductivity cell 24), and the specific cable 22 of the measuring unit 20 and the device main body. An extension cable 30 that can be attached to and detached from the apparatus 10 can be connected between the measurement unit 20 and the apparatus main body 10.

  The case where the extension cable 30 is connected between the measurement unit 20 and the apparatus main body 10 to measure the electrical conductivity will be described. When measuring the electrical conductivity, the measurement unit 20 is placed in a container 6 such as a beaker. It is immersed in the stored solution 61 to be measured. Then, an AC voltage is applied between the electrodes 24a and 24b of the measuring unit 20 from the AC power source for measuring electrical conductivity via the corresponding core wires in the specific cable 22 and the extension cable 30, and the current flowing at that time is specific. It is detected by the electrical conductivity detection circuit 14 of the apparatus body 10 through the corresponding core wires in the cable 22 and the extension cable 30. At this time, a direct-current voltage is applied to the temperature sensor 21 from the direct-current power source for temperature measurement via the corresponding cable in the specific cable 22 and the extension cable 30 to correspond to the temperature of the solution 61 to be measured. The output signal of the temperature sensor 21 corresponding to the electrical resistance value of the thermistor is detected by the temperature detection circuit 15 of the apparatus main body 10 via the corresponding core wires in the inherent cable 22 and the extension cable 30. The output signals from the electrodes 24a and 24b and the temperature sensor 21 are appropriately amplified by the electrical conductivity detection circuit 14 and the temperature detection circuit 15, respectively, and then input to the A / D converter 16, where A / D converted and input to the controller 11.

  When the extension cable 30 is not used, the measurement unit 20 and the apparatus main body 10 are directly connected by connecting the measurement unit side connector 23 to the main unit connector 13. The operation described as being performed via the unique cable 22 and the extension cable 30 is performed only via the unique cable 22.

  The controller 11 calculates the electric conductivity by correcting the detected value such as a cell constant and temperature, and outputs a signal for displaying the electric conductivity on the display unit 17 provided in the apparatus main body 10, for example. In the present embodiment, the measurement unit 20 has two electrodes, but may have more electrodes.

Although details will be described later, generally, the controller 11 determines the detected value by the following equation (1),
kT = kt / {1 + α / 100 × (t−T)} (1)
(Where T is the reference temperature [° C.], t is the solution temperature [° C.], kT is the electrical conductivity [S / m] converted to T ° C., kt is the electrical conductivity [t / m] at t ° C., α is the temperature coefficient of the solution [%])
Is converted into the electrical conductivity at the reference temperature T. The reference temperature T is 25 ° C., for example. In general applications, the electrical conductivity can be measured with sufficient accuracy by setting the temperature coefficient α to 2.00%. The electrical conductivity kt (S / m) is obtained by multiplying the conductance value (S) obtained from the output signal of the electrical conductivity cell 24 by the cell constant (m ⁻¹ ) in the controller 11. can get.

2. Correction of Error in Temperature Measurement Value Next, a description will be given of a response to an error in the temperature measurement value by the temperature sensor 21 when the extension cable 30 is used in the measurement apparatus 1 of the present embodiment.

  As described above, in the two-wire temperature sensor 21 using the resistance temperature detector, when the extension cable 30 is further connected to the specific cable 22, the electrical resistance value of the core wire of the extension cable 30 depends on the resistance value. Temperature measurements are affected. In particular, when the length of the extension cable 30 is long (for example, a cable exceeding 10 m), the influence of the electrical resistance value of the core wire of the extension cable 30 on the measurement value is large.

As an example, the electrical resistance value of the core wire for the temperature sensor 21 provided in the extension cable 30 is about 3.65Ω / 10 m (365Ω / km), and the relationship between the electrical resistance value of the thermistor of the temperature sensor 21 and the temperature measurement value. Is 25 ° C. at 2.1 kΩ and 90 ° C. at 0.2078 kΩ. In this case, when the length of the extension cable 30 is 10 m and the temperature of the solution to be measured at 25 ° C. is measured, the combined resistance of the temperature sensor 21 and the core wire of the extension cable 30 is expressed by the following equation:
2.1kΩ + 3.65Ω × 2 = 2.1073kΩ
The corresponding temperature measurement is 24.93 ° C., giving an error of about 0.3%. When the temperature of the measured solution at 90 ° C. is measured, the combined resistance of the temperature sensor 21 and the core wire of the extension cable 30 is expressed by the following equation:
0.2078kΩ + 3.65Ω × 2 = 0.151kΩ
The corresponding temperature measurement is 88.82 ° C., giving an error of about 1.3%.

  Thus, the influence of the characteristics of the extension cable 30, here the length, on the temperature measurement value may not be negligible.

  Further, when a plurality of types of extension cables 30 having different characteristics, here lengths, can be used for the apparatus main body 10, it is necessary to correct measurement values according to the extension cables 30.

  Therefore, in this embodiment, the conversion information that provides the controller 11 with information (conversion information) for associating the detection signal from the temperature sensor 21 with the temperature measurement value according to the characteristics of the extension cable 30 to the measurement device 1. Providing means is provided. Then, the controller 11 uses the conversion information provided by the conversion information providing means based on the detection signal input from the temperature sensor 21 of the measurement unit 20 connected to the apparatus main body 10 via the extension cable 30. Then, a temperature measurement value corresponding to the characteristics of the extension cable 30 is obtained.

  In this embodiment, the extension cable 30 is provided with characteristic information providing means for providing the controller 11 with information (characteristic information) relating to the characteristics of the extension cable 30.

  In particular, in this embodiment, the characteristic information providing means is the extension cable side storage medium 34 included in the extension cable 30 in which information related to the characteristics of the extension cable 30 is stored. In this embodiment, the conversion information providing means is the main body side storage medium 12 included in the apparatus main body 10.

  The controller 11 is connected to the apparatus main body 10 via the extension cable 30 using the conversion information provided from the main body side storage medium 12 according to the characteristic information stored in the extension cable side storage medium 34. Based on the output voltage value of the temperature sensor 21 of the measurement unit 20, a temperature measurement value corrected according to the characteristics of the extension cable 30 is obtained.

  As the extension cable side storage medium 34, an EEPROM (Electrically Erasable Programmable Read-Only Memory), flash memory, RAM with battery backup, EPROM, one-time ROM, CPU with memory, etc. are used. can do. In this embodiment, an EEPROM is used. For example, as shown in FIGS. 1 and 2, the extension cable side storage medium 34 can be attached to a printed circuit board in the first extension connector 32. Alternatively, the extension cable storage medium 34 can be attached to a printed circuit board provided on the extension cable main body 31 or the second extension connector 33. Thus, the controller 11 is stored in the extension cable side storage medium 34 via the corresponding signal lines and contacts provided in the extension cable 30 at a predetermined timing in a state where the extension cable 30 is connected to the apparatus main body 10. Information can be read.

  In this embodiment, the extension cable side storage medium 34 stores information related to the length of the extension cable 30 as characteristic information. In particular, in the present embodiment, information indicating the length of the extension cable 30 is stored as information relating to the length of the extension cable 30.

  The information stored in the extension cable side storage medium 34 is stored in the state where the extension cable side storage medium 34 is incorporated in the extension cable 30 at the time of manufacture of the measuring unit 20 or at the time of factory shipment, or at the time of manufacture. Can be stored in the extension cable-side storage medium 34 in a state where it is not yet incorporated into the extension cable 30 alone or together with other elements.

  As the main body side storage medium 12, EEPROM, flash memory, RAM with battery backup, EPROM, one-time ROM, CPU with memory, and the like can be used. In this embodiment, an EEPROM is used. The controller 11 can read information stored in the main body side storage medium 12 at a predetermined timing.

  In this embodiment, the output voltage value of the temperature sensor 21 is calculated from the thermistor, the corresponding core wires in the fixed cable 22 and the extension cable 30, the measurement unit side connector 23, the first and second extension connectors 32 and 33. The value is detected by the temperature detection circuit 15 via the main body side connector 13, and the signal is processed by the A / D converter 16 and input to the controller 11 as digital information indicating the output voltage value.

  Next, the procedure for correcting the temperature measurement value will be described more specifically.

First, the controller 11 once converts the output voltage value converted by the A / D converter 16 into an electrical resistance value including the electrical resistance value of the core wire itself of the extension cable 30. In this embodiment, a two-wire type temperature sensor 21 is used. Therefore, the electrical resistance value R of the core wire itself of the extension cable 30 is expressed by the following equation (2): the electrical resistance value per unit length of the core wire itself of the extension cable 30 and the length of the extension cable 30. After multiplying, it is determined by doubling this.
R = Rk × L × 2 (2)
(However, Rk is the electrical resistance per unit length of the extension cable core [Ω / m], L is the extension cable length [m])

  Then, the controller 11 calculates the electrical resistance value of the core wire itself of the extension cable 30 obtained as described above from the electrical resistance value converted once including the electrical resistance value of the core wire itself of the extension cable 30. The subtracted electric resistance value is obtained as the electric resistance value of the thermistor.

  Next, the controller 11 converts the electrical resistance value of the thermistor obtained as described above into a temperature measurement value. In this case, the conversion formula can be divided into several types according to the range of the electrical resistance value of the thermistor. In this embodiment, the relational expression is stored in the main body side storage medium 12 so that the relation between the range of the electrical resistance value of the thermistor and the corresponding conversion expression is associated.

  The controller 11 can obtain a temperature measurement value by reading a conversion equation corresponding to the range in which the electrical resistance value of the thermistor obtained as described above falls within the range, and converting it using the conversion equation. This value is a temperature measurement value corrected according to the length of the extension cable 30.

  As described above, in this embodiment, the extension cable storage medium 34 stores information indicating the length of the extension cable 30 as the characteristic information. The main body-side storage medium 12 includes, as conversion information, the electrical resistance value per unit length of the core wire of the extension cable 30 and the extension cable corresponding to the extension cable 30 that can be attached to and detached from the apparatus main body 10 and the measurement unit 20. Information for obtaining the electrical resistance value of the core wire itself of the extension cable 30 from the length of 30 and the electrical resistance value of the thermistor obtained by subtracting the electrical resistance value of the core wire itself of the extension cable 30 (Information) is stored. That is, in this embodiment, the conversion information includes the characteristics (length in this embodiment) of the extension cable 30 and the characteristics of the extension cable 30 in the process of obtaining the temperature measurement value from the detection signal by the controller 11 as a converter. Information relating to the value to be subtracted from the processing value according to (in this embodiment, the core wire itself of the extension cable 30 corresponding to the length of the extension cable 30 to be subtracted from the electrical resistance value obtained from the output voltage value of the temperature sensor 21 Information on the electrical resistance value) and information indicating the relationship between the And the controller 11 as a converter calculates | requires the measured value (correction value) by which the error part according to the characteristic of the extension cable 30 was subtracted using this relationship. Further, in this embodiment, the main body side storage medium 12 stores information (calculation formula) for obtaining a temperature measurement value from the electrical resistance value of the thermistor for each range of the electrical resistance value of the thermistor as conversion information. ing.

  It should be noted that the length of the extension cable 30 and the corresponding electrical resistance value of the core of the extension cable 30 are related to the calculation formula as described above for obtaining the electrical resistance of the core of the extension cable 30 itself. The attached data table created in advance may be stored in the main body side storage medium 12. Further, as information indicating the relationship between the electrical resistance value of the thermistor and the temperature measurement value, a data table created in advance may be stored in the main body side storage medium 12 instead of the above-described arithmetic expression. . The information indicating the relationship between the detection signal of the temperature sensor 21 and the temperature measurement value includes the relationship between the electrical resistance value of the thermistor and the temperature measurement value, and the output signal of the temperature sensor 21 is A / D converted. An arbitrary form of detection signal such as an output voltage value converted by the device 16 may be associated with a temperature measurement value.

  As will be described in detail later, when measuring the electrical conductivity, the controller 11 calculates the electrical conductivity according to the above-described equation (1), and uses the extension cable 30 as described above as the temperature of the solution to be measured. The temperature measurement value obtained according to the length of the is used. In addition, the controller 11 may output a signal for displaying the temperature measurement value on the display unit 17.

  The controller 11 may read information from the extension cable side storage medium 34 for each measurement, but stores the information once read from the extension cable side storage medium 34 in the main body side storage medium 12, for example, the power source of the apparatus main body 10. The information once read and stored in the main body side storage medium 12 may be used until is turned off or until the extension cable 30 is replaced or removed.

  The characteristic information providing means is preferably a storage medium such as an electronic memory, as in this embodiment, in terms of cost, ease of information transmission, and the amount of information that can be attached. is there. This storage medium may be a non-contact type capable of wireless communication with the apparatus main body. In this embodiment in which the characteristic information providing means is a storage medium, the controller 11 has a function of means for reading and recognizing the stored contents.

  Here, in the present embodiment, as described above, the electrical resistance value of the core wire itself of the extension cable 30 is obtained from the length of the extension cable 30 and extended from the electrical resistance value converted from the output voltage value of the temperature sensor 21. The electrical resistance value of the thermistor was obtained by subtracting the electrical resistance value of the core wire itself of the cable 30, and the electrical resistance value of the thermistor was converted into a temperature measurement value. Alternatively, information indicating the relationship between the detection signal for each characteristic of the extension cable 30 and the temperature measurement value can be stored in the main body side storage medium 12 as the conversion information. And the controller 11 shows the relationship between the detection signal according to the characteristic of the extension cable 30 provided from the main body side storage medium 12 according to the characteristic information stored in the extension cable side storage medium 34 and the temperature measurement value. Using the information, a temperature measurement value corresponding to the characteristics of the extension cable 30 can be obtained based on the detection signal input from the temperature sensor 21 of the measurement unit 20 connected to the measurement apparatus 10 via the extension cable 30. it can. For example, the main body side storage medium 12 stores, as the conversion information, information in which the output voltage value of the temperature sensor 21 of the measuring unit 20 and the temperature measurement value are associated with each other related to the length of the extension cable 30. Can be made. In other words, the extension cable storage medium 34 stores information indicating the length of the extension cable 30 as characteristic information. The main body side storage medium 12 has an output voltage value and a temperature measurement value of the temperature sensor 21 associated with each piece of information indicating the length of the extension cable 30 that can be attached to and detached from the apparatus main body 10 and the measurement unit 20. An associated data table is stored. The controller 11 obtains a temperature measurement value (correction value) corresponding to the length of the extension cable 30 using this data table. In this case, the controller 11 reads information indicating the length of the extension cable 30 from the extension cable side storage medium 34 and recognizes the length. Then, the controller 11 selects a data table indicating the relationship between the output voltage value and the temperature measurement value corresponding to the recognized length of the extension cable 30 and inputs from the temperature detection circuit 15 using the selected data table. The measured temperature value corresponding to the output voltage value to be read is read.

  Note that the extension cable-side storage medium 34 does not include information indicating the length of the extension cable 30 as information on the length of the extension cable 30 as characteristic information, but the type, model, serial number, etc. of the extension cable 30. Identification information can be stored. In other words, the characteristic information is information that allows the controller 11 to recognize it and correct the measured value according to the characteristic (length in this embodiment) of the extension cable 30 connected to the apparatus body 20. Good. When using identification information such as the type, model, and serial number of the extension cable 30 as the characteristic information, the conversion information can be recognized so that the characteristic (length in this embodiment) itself of the extension cable 30 can be recognized from the identification information. For example, information for associating the characteristic with the identification information can be stored in the main body side storage medium 12 as a data table, for example. Then, the controller 12 can recognize the length of the extension cable 30 from the identification information using the data table. Alternatively, as in the above-described alternative method, regarding the aspect using the data table in which the characteristic (length in the present embodiment) itself of the extension cable 30 is associated with certain information, the identification information is used instead of the characteristic itself. And a data table in which the information to be associated is associated.

3. Correction of Electric Conductivity Error Next, a description will be given of a response to an error in an electric conductivity measurement value by the electric conductivity cell 24 when the extension cable 30 is used in the measurement apparatus of the present embodiment.

  In the present embodiment, the measurement unit 20 has a cell constant determined in advance with the fixed cable 22, and the cell constant is provided together with the measurement unit 20 and set in the apparatus main body 10. For example, the cell constant is stored in advance in the measurement unit side storage medium 25 included in the measurement unit 20, read by the apparatus main body 10 side, stored in the apparatus main body side storage medium 12, and the value of the cell constant is used as the electric constant. The conductivity measurement value may be calculated and corrected, and displayed as electrical conductivity. As the measurement unit side storage medium 25, the same one as the extension cable side storage medium 34 can be used.

  However, as described above, when the extension cable 30 is further connected to the specific cable 22, the measured electrical conductivity is affected by the electrical resistance value of the core wire of the extension cable 30. In particular, when the length of the extension cable 30 is long (for example, a cable exceeding 10 m), the influence of the electrical resistance value of the core wire of the extension cable 30 on the measurement value is large.

As an example, consider a case where the electrical resistance value of the core wire for the electrical conductivity cell 24 included in the extension cable 30 is about 0.6Ω / 10 m (62.4Ω / km). At this time, when the cell constant is 100 m ⁻¹ , the equivalent resistance 10Ω is 10 S / m in terms of electrical conductivity. Therefore, if the length of the extension cable 30 is 10 m, the error due to the extension cable 30 is expressed by the following equation:
10Ω + 0.6Ω × 2 = 11.2Ω
The electric conductivity display is 8.9 S / m, and an error of about 11% occurs.

  As described above, the influence of the characteristic of the extension cable 30, here, the length, on the measured electric conductivity may not be negligible.

  Therefore, in the present embodiment, information (conversion information) for associating the measurement device 1 with the detection signal from the electrical conductivity cell 24 and the electrical conductivity measurement value according to the characteristics of the extension cable 30 is sent to the controller 11. A conversion information providing means is provided. Then, the controller 11 uses the conversion information provided by the conversion information providing means to detect the detection signal input from the electrical conductivity cell 24 of the measurement unit 20 connected to the apparatus body 10 via the extension cable 30. Based on this, a measured electric conductivity value corresponding to the characteristics of the extension cable 30 is obtained.

  Further, in the present embodiment, as described above regarding the correction of the error of the temperature measurement value, the characteristic information providing means for providing the controller 11 with the information (characteristic information) relating to the characteristic of the extension cable 30 to the extension cable 30, An extension cable storage medium 34 in which information related to the characteristics of the extension cable 30 is stored is provided. Further, in the present embodiment, as described above regarding the correction of the error of the temperature measurement value, the apparatus main body 10 is provided with the main body side storage medium 12 as the conversion information providing means. Information for associating the detection signal with the measured electric conductivity according to the characteristics of the extension cable 30 is stored.

  The controller 11 is connected to the apparatus main body 10 via the extension cable 30 using the conversion information provided from the main body side storage medium 12 according to the characteristic information stored in the extension cable side storage medium 34. Based on the output signal of the electrical conductivity cell 24 of the measuring unit 20, the electrical conductivity measurement value corrected according to the characteristics of the extension cable 30 is obtained.

  In this embodiment, the output signal of the electrical conductivity cell 24 is transmitted from the electrodes 24a and 24b to the corresponding core wires in the fixed cable 22 and the extension cable 30, the measurement unit side connector 23, and the first and second extensions. The signal is detected by the electrical conductivity detection circuit 14 via the connectors 32 and 33 and the main body side connector 13, and the signal is processed by the A / D converter 16 and input to the controller 11 as digital information indicating the value of the output signal. Value.

  Next, the procedure for correcting the measured electric conductivity will be described more specifically.

First, the controller 11 corrects the electrical resistance value of the core wire of the extension cable 30 (extension cable correction) before performing temperature compensation of the measured electric conductivity. Specifically, the controller 11 obtains an electrical conductivity measurement value ktr obtained by performing the extension cable correction by the following equation (3).
ktr = C / {(C / kt) -R} (3)
(Where ktr is the electric conductivity [S / m] after the extension cable correction, kt is the electric conductivity [S / m] before the temperature compensation and before the extension cable correction, and C is the cell constant [m ⁻¹ ], R Is the electrical resistance of the extension cable core [Ω])

In the above formula (3), the electrical resistance value R of the core wire of the extension cable 30 is set to the electrical resistance value Rk per unit length of the core wire of the extension cable 30 as shown in the following formula (4). It is obtained by multiplying the value obtained by multiplying the length L by a factor of two.
R = Rk × L × 2 (4)
(However, Rk is the electrical resistance per unit length of the extension cable core [Ω / m], L is the extension cable length [m])

  The relationship shown in the above equation (4) is a data table in which the length of the extension cable 30 and the corresponding electrical resistance value of the core wire of the extension cable 30 are associated instead of the arithmetic expression. It can be set in advance.

  In addition, C / kt in the above formula (3) corresponds to the reciprocal of the conductance value obtained from the output signal from the electrical conductivity cell 24 of the measuring unit 20 and includes the electrical resistance value of the extension cable 30. This is consistent with the combined resistance value. Therefore, {(C / kt) -R} in the above formula (3) is recognized as a true electrical resistance value between the electrodes 24a and 24b. Then, 1 / {(C / kt) −R} in the above formula (3) is recognized as a conductance value (S) corrected according to the length of the extension cable 30. Then, the measured electric conductivity ktr is a value obtained by multiplying the cell constant C and the conductance value (S) corrected according to the length of the extension cable 30 as described above, as in the above equation (3). Become.

  Thus, the controller 11 can correct the electrical resistance value of the core wire of the extension cable 30 by the above equation (3), and obtain the electrical conductivity measurement value ktr that eliminates the influence of this amount. .

Next, the controller 11 performs temperature compensation of the measured electrical conductivity value ktr after the extension cable correction obtained as described above, so that the electrical conductivity measurement value kTr after the intended extended cable correction and temperature compensation is performed. Ask for. Specifically, the controller 11 obtains the electrical conductivity value kTr from the following equation (5), which is the same as the equation shown in the above equation (1).
kTr = ktr / {1 + α / 100 × (t−T)} (5)
(Where kTr is the electric conductivity [S / m] after the extension cable correction and temperature compensation, ktr is the electric conductivity [S / m] after the extension cable correction obtained by the equation (3), and T is the reference temperature. [° C.], t is the temperature of the solution [° C.], α is the temperature coefficient of the solution [%])

  For example, the reference temperature T can be 25 ° C. and the temperature coefficient α can be 2.00%. Furthermore, in this embodiment, as the solution temperature t, a temperature measurement value (correction value) obtained according to the length of the extension cable 30 as described above is used. In addition, when calculating | requiring an electrical conductivity measured value, when it is not necessary to use the temperature measured value corrected according to the length of the extension cable 30, you may use the temperature measured value which is not correct | amended.

  Thus, in this embodiment, the extension cable side storage medium 34 stores information indicating the length of the extension cable 30 as characteristic information. In the main body side storage medium 12, an arithmetic expression (for calculating the electrical resistance value R of the core wire of the extension cable 30 corresponding to the extension cable 30 detachable from the apparatus main body 10 and the measuring unit 20 as conversion information ( Using the above equation (4)) or data table and the electrical resistance value R of the core wire of the extension cable 30 obtained by the above equation (4), the electrical conductivity measurement value ktr after the extension cable correction is obtained. An arithmetic expression (the above expression (3)) is stored. In other words, in the present embodiment, the conversion information is obtained by the extension cable 30 in the process of obtaining the electrical conductivity measurement value from the characteristic (length in the present embodiment) of the extension cable 30 and the detection signal by the controller 11 as the converter. The information on the value to be subtracted from the processing value according to the characteristics of the extension cable 30 according to the length of the extension cable 30 to be subtracted from the electrical resistance value obtained from the output signal of the electrical conductivity cell 24 in this embodiment. Information on the electrical resistance value of the core wire itself). And the controller 11 as a converter calculates | requires the electrical conductivity measured value (correction value) by which the error part according to the characteristic of the extension cable 30 was subtracted using this relationship.

  That is, in the main body side storage medium 12, as the conversion information, the length of the extension cable 30 that can be attached to and detached from the apparatus main body 10 and the measurement unit 20, and the electrical wire of the core for the electrical conductivity sensor 24 in the corresponding extension cable 30 Electricity is calculated using an arithmetic expression (formula (4)) or a data table in which a resistance value or a conductance value is related, and an electric resistance value or a conductance value of a core wire for the electric conductivity cell 24 in the extension cable 30. An arithmetic expression (the above expression (3)) for correcting the electric resistance value or the conductance value obtained from the output signal of the conductivity cell 24 is stored.

  Furthermore, in the present embodiment, the storage medium 12 on the main body side uses an arithmetic expression for obtaining a temperature-compensated electric conductivity measurement value using the electric conductivity measurement value ktr after the extension cable correction as conversion information (above-mentioned Equation (3)) is stored.

  Here, in the present embodiment, as described above, the electrical resistance value R of the core wire itself of the extension cable 30 is obtained from the length of the extension cable 30, and this is used to measure the electric conductivity measured value ktr after the extension cable correction. The electrical conductivity measurement value ktr after the extension cable correction was converted into the electrical conductivity measurement value kTr after temperature compensation. Alternatively, a data table in which the length of the extension cable 30, the measured electric conductivity value ktr after correction of the extended cable, and the measured electric conductivity value kTr after temperature compensation are created, and the storage medium on the main body side is created. 12 may be stored. For example, as the conversion information, the electrical conductivity kt before the temperature compensation and before the extension cable correction and the electrical conductivity measured value ktr after the extension cable correction for each piece of information related to the length of the extension cable 30 are related. The data table can be stored in the main body side storage medium 12. In this case, the controller 11 obtains the measured electrical conductivity ktr after the correction of the extension correction cable corresponding to the length of the extension cable 30 using the data table, and then the electrical conductivity after the temperature compensation in the same manner as described above. The measured value kTr can be obtained.

  As described above regarding the correction of the temperature measurement value error, the information relating to the length of the extension cable 30 stored in the extension cable-side storage medium 34 is not information indicating the length of the extension cable 30 but an extension. Identification information such as the type, model, and serial number of the cable 30 can be used.

4). Setting of Conversion Information Providing Unit Here, the conversion information (arithmetic formula and data table) stored in the main body side storage medium 12 as the conversion information providing unit as described above is stored in advance before the user starts using it. In a state where the main body side storage medium 12 is incorporated in the apparatus main body 10 at the time of manufacture or at the time of shipment from the factory, or in a state where the main body side storage medium 12 is not yet incorporated in the apparatus main body 10 alone or together with other elements. It can be stored in the main body side storage medium 12.

  Further, the conversion information is inputted in whole or in part by using the keys (operation keys) of the operation unit 18 of the apparatus main body 10 as input means (conversion information input means), and the main body side storage medium. 12 can be stored. Also, the conversion information is created entirely or partly in an external device such as a PC (personal computer) or downloaded from another device via a network in an external device such as a PC. After being stored in the storage means of the external device, the information may be transmitted to the apparatus main body 10 via the information transmission medium external to the apparatus main body 10 and stored in the main body side storage medium 12.

  Thereby, it is possible to easily cope with a case where conversion information needs to be changed or updated due to an increase in the number of usable extension cables 30 or a design change. In particular, the conversion information created or downloaded by a PC or the like is collectively loaded into the main body side storage medium 12 via the information transmission medium external to the apparatus main body 10 so that the relevant information can be easily, quickly, and accurately obtained. It is preferable that information can be set.

  For example, as shown in FIG. 3, the apparatus main body 10 includes a first interface unit 19 a connected to the controller 11 and capable of USB (Universal Serial Bus) connection, and a LAN (Local Area Network) connection. A possible second interface part 19b may be provided.

  In this case, the operator takes the conversion information from an information transmission medium (information communication or storage medium) external to the measuring apparatus 1 instead of manually inputting the conversion information manually using a key provided on the apparatus body 10. The conversion information is set and stored in the main body side storage medium 12.

  Here, the information transmission medium may be a detachable storage medium that is detachably connected to the measuring apparatus 1 and a device (external device) outside the measuring apparatus 1 such as a PC. The information transmission medium may be a communication unit that connects the measuring apparatus 1 and an external device such as a PC so as to communicate with each other.

  For example, the measuring apparatus 1 includes a first interface unit 19a capable of USB connection, which is a reading unit serving as a capturing unit, in the apparatus main body 10. The first interface unit 19 a is connected to the controller 11. A USB memory (flash memory) 2 as a removable storage medium is detachably connected to the first interface unit 19a. Then, the controller 11 takes in desired conversion information stored in advance in the USB memory 2 from the USB memory 2 connected to the first interface unit 19a via the first interface unit 19a, and the main body side It is stored in the storage medium 12.

  The conversion information is created in an external device such as a PC, and is usually stored in a storage device such as a hard disk or the like that is once included in the external device (that is, built in or connected to the external device such as a PC). Is remembered. This external device such as a PC has an interface unit capable of USB connection as reading / writing means. In this case, the data to be created may be obtained by the user himself / herself through experiments or the like, but the manufacturer of the apparatus main body 10, the measuring unit 20, or the extension cable 30 can provide the data. The conversion information is input by using arbitrary software such as spreadsheet software installed in a PC as an external device, for example, and stored in a storage unit of the external device such as a PC as a data table in a CSV format, for example. It can be memorized. Alternatively, such conversion information can be downloaded from other devices via a network (LAN, Internet, etc.) in an external device such as a PC. In this case, the manufacturer of the apparatus main body 10, the measurement unit 20, or the extension cable 30 can provide the conversion information so that it can be downloaded.

  The conversion information stored in the storage means of the external device can be written into the USB memory 2 by connecting the USB memory 2 to the external device. Next, as described above, the USB memory 2 can be removed from the external device and connected to the measuring apparatus 1, and conversion information can be taken into the measuring apparatus 1 from the USB memory 2 at once.

  The operation of storing the conversion information in the main body side storage medium 12 using the USB memory 2 may be started when the operator inputs a start instruction using a key provided on the operation unit 18. Alternatively, this operation may be started automatically when the controller 11 recognizes that the USB memory 2 is connected to the first interface unit 19a.

  On the other hand, the measuring apparatus 1 includes a second interface unit 19b in the main body 10, which is a receiving unit serving as a capturing unit and capable of LAN connection. The second interface unit 19 b is connected to the controller 11. One end of the LAN cable 3 which is an information communication cable as a communication means is detachably connected to the second interface unit 19b. For example, the other end of the LAN cable 3 is detachably connected to the PC 4 as an external device. The PC 4 as an external device has an interface unit capable of LAN connection as reception / transmission means. Then, the controller 11 takes in the desired conversion information stored in advance in the storage unit as described above from the storage unit of the PC 4 via the second interface unit 19b, and stores it in the main body side storage medium 12. Remember. Alternatively, conversion information input in the PC 4 can be directly written in the main body side storage medium 12 of the measuring apparatus 1.

  The operation of storing the conversion information in the main body side storage medium 12 using the LAN cable 3 may be started when the operator inputs a start instruction through the operation unit of the PC 4. Or this operation | movement may be started by inputting a start instruction | indication with the key provided in the operation part 18 of the measuring apparatus 1. FIG.

  That is, the conversion information setting method includes (i) a step of inputting conversion information using an external device 4 (external device such as a PC) 4 of the measuring apparatus 1, and (ii) information on the input conversion information. A step of transmitting via a transmission medium; (iii) a step of taking the transferred conversion information into the measuring device 1; and (iv) a main body-side memory provided in the measuring device 1 Storing in the medium 12.

  In one embodiment, in the transmitting step (ii), the input conversion information is stored in the removable storage medium (USB memory) 2 from the external device 4 by a writing means provided in the external device 4. In the step (iii), the conversion information stored in the removable storage medium 2 that is detached from the external device 4 and connected to the measuring device 1 is read in the measuring device 1. Reading by the first interface unit 19a. In another embodiment, in the step (ii), the input conversion information can be communicated between the external device 4 and the measuring apparatus 1 by the transmission means provided in the external device 4. Including the step of transmitting through the communication means (LAN cable) 3 to be connected, and the step (iii) taking in the conversion information transmitted through the communication means 3 includes a receiving means (second Interface portion) 19b.

  According to an external device such as a PC, a data table composed of several to several tens of setting data, for example, is relatively easy by using an attached keyboard having better operability than the keys provided on the measuring apparatus 1. The conversion information creation time can be shortened, and the occurrence of errors can be reduced. In addition, when the conversion information is downloaded from the network, the trouble of creating the conversion information can be saved.

  In the above description, the removable storage medium has been described as being the USB memory 2. However, for example, any other removable storage medium such as a memory card (flash memory), a flexible disk, and a removable hard disk is used. be able to. What is necessary is just to comprise the interface part as a reading means / writing means so that it may adapt to the storage medium of each aspect. In the above description, the information communication cable has been described as a LAN cable directly connected to the measuring apparatus 1 and the PC 4. However, for example, any other information communication cable such as an RS232C cable or a USB cable is used. be able to. In the above embodiment, the communication means is connected by wire, but may be connected wirelessly. Furthermore, the information communication cable is not limited to the direct connection between the measuring apparatus 1 and the PC 4, but can be connected to a plurality of PCs 4 connected to the LAN, or another single or a plurality of measurements. The device 1 may be connectable. In the above description, the case where the measurement apparatus 1 includes both the first and second interface units 19a and 19b has been described as an example, but either one of them may be provided.

5). Effect As described above, according to the present embodiment, when the extension cable 30 is connected between the measurement unit 20 and the apparatus main body 10, a plurality of types of extension cables 30 having different lengths can be used. Even in this case, a more accurate measurement value can be obtained more easily according to the length of the extension cable 30.

6). Modifications The following modifications can be considered for this embodiment.

  In the present embodiment, the characteristic information is information related to the length of the extension cable 30, and the case where the error such as the temperature measurement value due to the difference in the length of the extension cable 30 is corrected has been described. However, even if the length is the same, the difference in characteristics (cross-sectional area, etc.) related to the electrical resistance value per unit length of the core of the extension cable 30, or the length of the extension cable 30 and the unit of the core of the extension cable 30 Differences in both characteristics (cross-sectional area, etc.) related to the electrical resistance value per length also cause errors in the temperature measurement value and the electrical conductivity measurement device.

  Therefore, when the length of the usable extension cable 30 is constant and the electrical resistance value per unit length of the core wire is different, the characteristic information includes information indicating the cross-sectional area of the core wire of the extension cable 30 and the like. Further, the information may indicate information related to the electrical resistance value per unit length of the core wire of the extension cable 30. In this case, the conversion information is, for example, an arithmetic expression for obtaining the electrical resistance value of the core wire itself of the extension cable 30 from information indicating the cross-sectional area of the extension cable 30, or information indicating the cross-sectional area of the extension cable 30. And a data table in which the electrical resistance value of the core wire itself of the extension cable 30 is associated. Alternatively, the conversion information may be information such as a data table indicating the relationship between the detection signal and the temperature measurement value or the electrical conductivity measurement value for each information indicating the cross-sectional area of the extension cable 30.

  In addition, when a plurality of types of extension cables 30 having different lengths of the extension cable 30 and characteristics (cross-sectional area, etc.) related to the electrical resistance value per unit length of the core of the extension cable 30 can be used. The characteristic information may be information related to the length of the extension cable 30 and information related to the electrical resistance value per unit length of the extension cable 30 (such as a cross-sectional area). In this case, the conversion information is, for example, for obtaining the electrical resistance value of the core wire itself of the extension cable 30 from the information related to the length of the extension cable 30 and the information indicating the cross-sectional area of the core wire of the extension cable 30. The combination of the calculation formula or the information related to the length of the extension cable 30 and the information indicating the cross-sectional area of the core wire of the extension cable 30 and the electrical resistance value of the core wire itself of the extension cable 30 are related. You may have a data table. Alternatively, the conversion information is data indicating the relationship between the detection signal and the temperature measurement value or the electrical conductivity measurement value for each combination of information relating to the length of the extension cable 30 and information indicating the cross-sectional area of the extension cable 30. Information such as a table may be used.

  The characteristic information includes the length of the extension cable 30, the characteristic (cross-sectional area, etc.) related to the electrical resistance value per unit length of the core of the extension cable 30, or both of the extension cable 30. The information which shows the electrical resistance value of the core wire of the extension cable 30 may be sufficient. In this case, the information itself indicating the electrical resistance value is used in place of the electrical resistance value of the core wire itself of the extension cable 30 described as being obtained by an arithmetic expression or the like in the above-described embodiment, and thus described in the above-described embodiment. In the same manner as described above, the temperature measurement value and the electric conductivity measurement value can be corrected.

  As described above with respect to the length of the extension cable 30, characteristics (such as a cross-sectional area) relating to the electrical resistance value per unit length of the core wire of the extension cable 30, the length of the extension cable 30, and the length of the cable 22. Instead of the characteristics (cross-sectional area, etc.) of the electrical resistance value per unit length of the core wire itself, or the electrical resistance value itself of the core wire of the extension cable 30, the type, model, and manufacture of the extension cable 30 corresponding to them Identification information such as a number can be stored in the extension cable side storage medium 34 and used.

  As described above, according to the present embodiment, the measurement unit 20 can be attached to and detached from the apparatus main body 10, and the measurement apparatus 1 that can connect the extension cable 30 between the measurement unit 20 and the apparatus main body 10 is simpler. In addition, more accurate measurement values can be obtained according to the characteristics of the extension cable 30.

Example 2
Next, another embodiment of the measuring apparatus according to the present invention will be described. The basic configuration and operation of the measuring apparatus of the present embodiment are the same as those of the first embodiment. Accordingly, elements having the same functions or configurations as those of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the first embodiment, the characteristic information providing unit is the extension cable side storage medium 34 included in the extension cable 30. In such an embodiment, information relating to the characteristics of the extension cable 30 is automatically read on the apparatus body 10 side, and typically, an error in the measurement value due to the characteristics of the extension cable 30 is automatically corrected on the apparatus body 10 side. This is preferable.

  However, the present invention is not limited to such an embodiment, and the operator inputs information related to the characteristics of the extension cable 30 to the apparatus main body 10 so that the information related to the characteristics of the extension cable 30 on the apparatus main body 10 side. You may come to recognize.

  With reference to FIG. 1 or FIG. 2, as described in the first embodiment, as information related to the characteristics of the extension cable 30, for example, information related to the length of the extension cable 30 is connected to the apparatus main body 10 or Corresponding to the extension cable 30 to be connected, the operator inputs using the keys (operation keys) of the operation unit 18 of the apparatus body 10 as input means. Thereby, the controller 11 can recognize the input information. And the controller 11 can correct | amend a measured value according to the recognized information.

  Here, the information related to the characteristics of the extension cable 30 can be provided to the user by attaching the information to the extension cable 30 by describing it on the cable main body 31 or the first and second extension connectors 32 and 33. it can. Alternatively, the information related to the characteristics of the extension cable 30 can be provided to the user separately from the extension cable 30 by, for example, describing it on a printed matter of the extension cable 30 such as a package, specifications, and instructions.

  As described above, in the measurement apparatus 1 in which the measurement unit 20 can be attached to and detached from the apparatus main body 10 and the extension cable 30 can be connected between the measurement unit 20 and the apparatus main body 10 even with the configuration of the present embodiment. A more accurate measurement value can be easily obtained according to the characteristics of the extension cable 30.

Example 3
Next, still another embodiment of the measuring apparatus according to the present invention will be described. The basic configuration and operation of the measuring apparatus of the present embodiment are the same as those of the first embodiment. Accordingly, elements having the same functions or configurations as those of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  This embodiment is further different from the first and second embodiments in the characteristic information providing means.

  That is, as characteristic information providing means, physical quantity or state changing means such as switches, analog switches, resistors, capacitors, etc .; physical quantity generating means such as voltage generators, current generators, light generators; physical shape changes; or bars Information presenting means selected from the group consisting of codes can be used. These information presentation means can be provided in the 1st extension connector 32 for connecting the extension cable 30 to the main body side connector 13, for example. Information relating to the characteristics of the extension cable 30 is attached to these information presentation means in advance.

  On the other hand, on the apparatus main body 10 side, a recognition unit for recognizing information attached to the information presentation unit is provided. Corresponding to the various information presenting means, a recognition means capable of recognizing the information can be provided on the apparatus main body 10 side. For example, if the information presenting means is a physical quantity or state changing means, the recognizing means is a means for recognizing a change in the physical quantity or state, and if the information presenting means is a physical quantity generating means, the recognizing means accepts the physical quantity. If the information presenting means is a physical shape change, the information presenting means is a means for identifying the physical shape change. If the information presenting means is a bar code, the recognizing means uses a bar code. A means for identifying may be used.

  As described above, in the measurement apparatus 1 in which the measurement unit 20 can be attached to and detached from the apparatus main body 10 and the extension cable 30 can be connected between the measurement unit 20 and the apparatus main body 10 even with the configuration of the present embodiment. A more accurate measurement value can be easily obtained according to the characteristics of the extension cable 30.

Example 4
Next, still another embodiment of the measuring apparatus according to the present invention will be described. The basic configuration and operation of the measuring apparatus of the present embodiment are the same as those of the first embodiment. Accordingly, elements having the same functions or configurations as those of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  In this embodiment, the conversion information providing means is the measurement unit side storage medium 25 included in the measurement unit 20. In the present embodiment, the same information as that described as being stored in the main body storage medium 12 in the first embodiment is stored as conversion information in the measurement unit storage medium 25. That is, the conversion information is stored in advance in the measurement unit side storage medium 25 of the measurement unit 20 corresponding to the type of the extension cable 30 that can be connected to the measurement unit 20 and used.

  As the measurement unit side storage medium 25, an EEPROM, a flash memory, a RAM with battery backup, an EPROM, a one-time ROM, a CPU with memory, or the like can be used. In this embodiment, an EEPROM is used. For example, as shown in FIG. 4A, the measurement unit side storage medium 25 is provided in a cover provided at the end of the measurement unit main body 20a on which the electrodes 24a and 24b of the measurement unit 22 and the temperature sensor 21 are supported. Can be attached to a printed circuit board. Alternatively, the measurement unit side storage medium 25 is attached to a printed circuit board in the measurement unit side connector 23 for connecting the specific cable 22 to the main body side connector 13 or the second extension connector 33 as shown in FIG. be able to. Alternatively, the measurement unit side storage medium 25 can be attached to a printed circuit board provided on the unique cable 22. As a result, the controller 11 connects the corresponding signal lines and the corresponding contacts included in the specific cable 22 and the extension cable 30 at a predetermined timing in a state where the measurement unit 20 is connected to the apparatus main body 10 via the extension cable 30. Thus, the information stored in the measurement unit side storage medium 25 can be read.

  In the present embodiment, the controller 11 of the apparatus main body 10 performs the conversion read from the measurement unit side storage medium 25 in the same manner as the conversion information stored in the main body storage medium 12 in the first embodiment. Use the information to determine the measured value.

  Here, the conversion information is stored in the measurement unit side storage medium 25 in the state in which the measurement unit side storage medium 25 is incorporated in the measurement unit 20 at the time of manufacture or at the time of factory shipment before the user starts use. Can be stored in the measurement unit-side storage medium 25 in a state where it is not yet incorporated in the measurement unit 20 alone or together with other elements.

  Also, the conversion information is input in whole or in part by using the keys (operation keys) of the operation unit 18 of the apparatus main body 10 as an input means by the operator, and the measurement unit side through the apparatus main body 10. It can be stored in the storage medium 25. Also, the conversion information is created entirely or partly in an external device such as a PC (personal computer) or downloaded from another device via a network in an external device such as a PC. After being stored in the storage means of the external device, the information is transmitted to the apparatus main body 10 via the information transmission medium external to the apparatus main body 10 and stored in the measurement unit side storage medium 25 via the apparatus main body 10. It may be. At this time, the extension cable 30 may or may not be connected between the apparatus main body 10 and the measurement unit 20.

  That is, referring to FIG. 3, in the same manner as in the first embodiment, the conversion information is set in the main body side storage medium 12 using the first and second interface units 19a and 19b as the capturing means. 10, conversion information can be set in the measurement unit side storage medium 25 of the measurement unit 20 that is connected to the apparatus main body 10 directly or via the extension cable 30.

  At this time, the controller 11 included in the apparatus main body 10 functions as a writing unit that stores the conversion information stored in the measurement unit side storage medium 25 in the measurement unit side storage medium 25.

  As in the first embodiment, if the main body side storage medium 12 is provided in the apparatus main body 10, the information to be stored in the measurement unit side storage medium 25 is temporarily stored in the main body side storage medium 12. The stored information may be read and written to the measurement unit side storage medium 25.

  As described above, in the measurement apparatus 1 in which the measurement unit 20 can be attached to and detached from the apparatus main body 10 and the extension cable 30 can be connected between the measurement unit 20 and the apparatus main body 10 even with the configuration of the present embodiment. A more accurate measurement value can be easily obtained according to the characteristics of the extension cable 30.

Example 5
Next, still another embodiment of the measuring apparatus according to the present invention will be described. The basic configuration and operation of the measuring apparatus of the present embodiment are the same as those of the first embodiment. Accordingly, elements having the same functions or configurations as those of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the present embodiment, the extension cable side storage medium 34 included in the extension cable 30 functions as conversion information providing means.

  That is, in this embodiment, for example, as the conversion information related to the correction of the error of the temperature measurement value, the electrical resistance value of the core wire itself of the extension cable 30 is converted from the electrical resistance value converted from the output voltage value of the temperature sensor 21. Information (calculation formula) for subtraction can be stored in the extension cable side storage medium 34. Further, as the conversion information, information indicating the relationship between the detection signal corresponding to the characteristic of the extension cable 30 and the temperature measurement value can be stored in the extension cable side storage medium 34. That is, for example, among the information indicating the relationship between the detection signal and the temperature measurement value for each characteristic of the extension cable 30 described in the first embodiment, the relationship between the detection signal corresponding to the characteristic of the extension cable 30 and the temperature measurement value. Is stored in the extension cable side storage medium 34 of the extension cable 30.

  Further, for example, as conversion information relating to the correction of the error in the electric conductivity measurement value, information (calculation expression) corresponding to the above equation (3) to which the electric resistance value of the core wire itself of the extension cable 30 is applied is extended. It can be stored in the cable-side storage medium 34.

  Other conversion information described in the first embodiment may be stored in the extension cable side storage medium 34.

  In this embodiment, the controller 11 of the apparatus main body 10 stores the extension cable side in the same manner as in the first embodiment using the conversion information stored in the main body side storage medium 12 according to the characteristic information. A measurement value is obtained by directly using conversion information corresponding to the characteristics of the extension cable 30 read from the medium 34.

  Here, the conversion information is stored in a state where the extension cable side storage medium 34 is incorporated in the extension cable 30 at the time of manufacture or factory shipment before the user starts using the extension information, or at the time of manufacture. Can be stored in the extension cable side storage medium 34 in a state where it is not yet incorporated into the extension cable 30 together with a single element or other elements.

  Also, the conversion information is input in whole or in part by using the keys (operation keys) of the operation unit 18 of the apparatus main body 10 as an input means by the operator, and the extension cable side through the apparatus main body 10. It can be stored in the storage medium 34. Also, the conversion information is created entirely or partly in an external device such as a PC (personal computer) or downloaded from another device via a network in an external device such as a PC. After being stored in the storage means of the external device, the information is transmitted to the apparatus main body 10 via the information transmission medium external to the apparatus main body 10 and stored in the extension cable side storage medium 34 via the apparatus main body 10. It may be.

  That is, referring to FIG. 3, in the same manner as in the first embodiment, the conversion information is set in the main body side storage medium 12 using the first and second interface units 19a and 19b as the capturing means. 10, conversion information corresponding to the characteristics of the extension cable 30 can be set in the extension cable-side storage medium 34 of the extension cable 30 connected to the apparatus main body 10.

  At this time, the controller 11 included in the apparatus main body 10 functions as a writing unit that stores the conversion information stored in the extension cable side storage medium 34 in the extension cable side storage medium 34.

  As in the first embodiment, if the main body side storage medium 12 is provided in the apparatus main body 10, the information to be stored in the extension cable side storage medium 34 is temporarily stored in the main body side storage medium 12. The stored information may be read and written to the extension cable storage medium 34.

  As in this embodiment, the extension cable-side storage medium 34 included in the extension cable 30 stores the conversion information for the extension cable 34 itself, that is, in accordance with the characteristics of the extension cable 34. As in Examples 1 to 3, a more accurate measurement value can be obtained more easily and according to the characteristics of the extension cable 30. Further, according to the present embodiment, it is easy to cope with an increase in the types of extension cables 30 that can be used and design changes.

Example 6
Next, still another embodiment of the measuring apparatus according to the present invention will be described. The basic configuration and operation of the measuring apparatus of the present embodiment are the same as those of the first embodiment. Accordingly, elements having the same functions or configurations as those of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the above embodiment, a description has been given on the assumption that a single extension cable 30 is connected between the measurement unit 20 and the apparatus main body 10. However, as shown in FIG. It may be possible to connect between the unit 20 and the apparatus main body 10.

  In this case, for example, information indicating the length of each extension cable 30 as characteristic information can be stored in the extension cable side storage medium 34 included in each extension cable 30 as characteristic information providing means, for example. Then, the measured value is corrected in accordance with the overall characteristics of the connected extension cables 30 recognized from the characteristics of each extension cable 30. That is, for example, in the first embodiment, the processing performed using the information indicating the length of the single extension cable 30 can be performed using the information indicating the total length obtained by adding the lengths of the extension cables 30. it can. The controller 11 can add information indicating the length read from each extension cable side storage medium 34 and use it for subsequent processing.

  Also in the present embodiment, the characteristic information is not limited to information indicating the length itself, for example, any form of information capable of recognizing the length or the electrical resistance value corresponding to the length. It may be.

  As mentioned above, although this invention was demonstrated according to the specific embodiment, this invention is not limited to the above-mentioned embodiment, It can change and change variously as needed.

  For example, in the above-described embodiment, the measurement result of the measurement apparatus 1 has been described as being displayed on the display unit 17 provided in the apparatus main body 10, but is not limited thereto. For example, the measurement result can be printed and output by a printer connected to the main body 10. The measurement result is transmitted to an external device such as a PC that is communicably connected to the main body 10 and displayed on the display unit of the external device or printed by a printer connected to the external device. Can be output.

  Moreover, in the said Example, the measuring apparatus 1 is an electrical conductivity measuring apparatus, and the measurement part 20 is an electrical conductivity sensor with which the electrical conductivity cell 24 (electrode 24a, 24b) and the temperature sensor 21 were integrally provided. there were. However, the present invention is not limited to such an embodiment.

  For example, a measurement unit having a temperature detection element and a cable having a core wire connected to the temperature detection element is any other measurement probe such as a pH sensor, an ion sensor, or an ORP sensor incorporating the temperature detection element. Alternatively, it may be a single temperature sensor provided with a temperature detection element. In these cases, a configuration that only considers the response to the error of the temperature measurement value described above may be used. Moreover, the electric conductivity cell 24 may be a single electric conductivity sensor. In this case, it is only necessary to take into account only the response to the above-described error in the measured electrical conductivity. Naturally, in the electrical conductivity sensor including the electrical conductivity cell and the temperature sensor, it is also possible to adopt a configuration that takes into account only one of the above-described error of the temperature measurement value and the error of the electrical conductivity measurement value.

  When correcting the influence of the length of the cable or its core on the measurement value, the length of the cable or the core can often be represented by the length of the cable itself, but the core is more precisely. It is also possible to correct based on the length of.

It is a block diagram of one example of a measuring device concerning the present invention. It is a fragmentary sectional view which shows the attachment aspect of the extension cable side storage medium. It is a block diagram of other examples of a measuring device concerning the present invention. It is a fragmentary sectional view which shows the attachment aspect of a measurement part side storage medium. It is a block diagram of other examples of a measuring device concerning the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Measuring apparatus 10 Apparatus main body 11 Controller (converter)
DESCRIPTION OF SYMBOLS 12 Main body side storage medium 20 Measuring part 21 Temperature sensor 22 Cable 23 Connector 25 Measuring part side storage medium 30 Extension cable 34 Extension cable side storage medium

Claims (20)

A measurement unit having a detection element and a specific cable having a core wire connected to the detection element; a device main body to which the measurement unit is detachably connected by the specific cable; and the detection provided in the device main body A transducer for obtaining a measurement value based on a detection signal input from an element to the device body,
An extension cable having a core wire connected to the detection element can be connected between the measurement unit and the apparatus main body,
Conversion information providing means for providing the converter with conversion information for associating the detection signal with the measurement value according to the characteristics of the extension cable;
The converter uses the conversion information to respond to the characteristics of the extension cable based on the detection signal input from the detection element of the measurement unit connected to the apparatus body via the extension cable. Further, a measuring apparatus for obtaining the measured value.   The extension cable-side storage medium in which the characteristic information is stored is provided in the extension cable as characteristic information providing means for providing characteristic information relating to the characteristic of the extension cable to the converter. Item 2. The measuring device according to Item 1.   As the characteristic information providing means for providing characteristic information relating to the characteristic of the extension cable to the converter, the apparatus main body is provided with an input means for inputting the characteristic information by an operator. The measuring apparatus according to claim 1.   As characteristic information providing means for providing characteristic information relating to the characteristics of the extension cable to the converter, physical quantities or state changing means such as switches, analog switches, resistors, capacitors, etc., attached to the extension cable. An information presenting means selected from the group consisting of a physical quantity generating means such as a voltage generator, a current generator, a light generator; a physical shape change; or a bar code; The measuring apparatus according to claim 1, further comprising a recognizing unit configured to recognize the characteristic information attached to the information presenting unit.   The measuring apparatus according to claim 1, wherein the conversion information providing unit is a main body-side storage medium included in the apparatus main body.   The conversion information has a relationship between the characteristics of the extension cable and information related to a value to be subtracted from the processing value according to the characteristics of the extension cable in the process of obtaining the measurement value from the detection signal by the converter. The measurement apparatus according to claim 5, wherein the converter obtains the measurement value obtained by subtracting an error corresponding to a characteristic of the extension cable based on the relationship.   The conversion information is information indicating a relationship between the detection signal and the measurement value for each characteristic of the extension cable, and the converter is provided from the main body side storage medium according to the characteristic of the extension cable. The measurement apparatus according to claim 5, wherein the measurement value is obtained using information indicating a relationship between the detection signal and the measurement value according to characteristics of the extension cable.   The measurement apparatus according to claim 1, wherein the conversion information providing unit is a measurement unit-side storage medium included in the measurement unit.   The conversion information has a relationship between the characteristics of the extension cable and information related to a value to be subtracted from the processing value according to the characteristics of the extension cable in the process of obtaining the measurement value from the detection signal by the converter. The measurement apparatus according to claim 8, wherein the converter obtains the measurement value obtained by subtracting an error corresponding to a characteristic of the extension cable based on the relationship.   The conversion information is information indicating a relationship between the detection signal and the measurement value for each characteristic of the extension cable, and the converter is provided from the measurement unit side storage medium according to the characteristic of the extension cable. The measurement apparatus according to claim 8, wherein the measurement value is obtained using information indicating a relationship between the detection signal and the measurement value according to characteristics of the extension cable.   The measurement apparatus according to claim 8, wherein the apparatus main body includes writing means for storing the conversion information in the measurement unit-side storage medium.   The measuring apparatus according to claim 1, wherein the conversion information providing unit is an extension cable side storage medium included in the extension cable.   The conversion information has a relationship between the characteristics of the extension cable and information related to a value to be subtracted from the processing value according to the characteristics of the extension cable in the process of obtaining the measurement value from the detection signal by the converter. The measurement apparatus according to claim 12, wherein the converter obtains the measurement value obtained by subtracting an error corresponding to a characteristic of the extension cable based on the relationship.   The conversion information is information indicating a relationship between the detection signal and the measurement value according to the characteristics of the extension cable, and the converter converts the characteristics of the extension cable provided from the extension cable-side storage medium. The measurement apparatus according to claim 12, wherein the measurement value is obtained using information indicating a relationship between the corresponding detection signal and the measurement value.   The measurement apparatus according to claim 12, wherein the apparatus main body includes writing means for storing the conversion information in the extension cable side storage medium.   The measuring apparatus according to claim 1, wherein the apparatus main body includes a capturing unit that captures the conversion information from an information transmission medium outside the apparatus main body. (A) The information transmission medium is a detachable storage medium that is detachably connected to the apparatus main body, and the capturing unit is a reading unit that reads information from the detachable storage medium, or
(B) The information transmission medium is communication means for connecting a device external to the apparatus main body and the apparatus main body so as to be communicable, and the fetching means receives information transmitted via the communication means. The measuring device according to claim 16, wherein   The measuring apparatus according to claim 1, wherein the apparatus main body includes conversion information input means for inputting the conversion information by an operator.   The characteristic of the extension cable is that the extension cable or the length of the core wire in the extension cable, the characteristic relating to the electrical resistance value per unit length of the core wire in the extension cable, or both of them The measuring apparatus according to claim 1, wherein the measuring apparatus is characterized in that   The measuring device according to claim 1, wherein the characteristic of the extension cable is an electrical resistance value of the core wire in the extension cable.

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