JP2020012770A - Measurement device and body device of measurement device - Google Patents

Abstract

To allow a sensor, which is removable from the body device of a measurement device, to be identified if the sensor does not have a memory including the identification information of the sensor.SOLUTION: A measurement device 1 includes a sensor 10 removable from a body device 20. The sensor 10 includes an identification circuit 31 having a measurement electrode 11 and an identification resistance value R1. The device body 20 includes: measurement units 34 and 35 connected to the measurement electrode 11 of the sensor 10 by a signal line, the sensor being connected to the device body 20; an identification voltage generation circuit 51 connected by a signal line to an identification circuit 31 of the sensor 10 connected to the device body 20, the identification voltage generation circuit generating an identification voltage V2 according to an identification resistance value R1 of the identification circuit 31; a sensor identification unit 53 for identifying the sensor 10 connected to the device body 20 on the basis of the identification voltage V2; and cutting-off circuits SWa, SWb for cutting off the measurement units 34 and 35 from the identification circuit 31 and the identification voltage generation circuit 51 at a timing when the sensor 10 is identified.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a measuring device and a main device of the measuring device.

  As a conventional measuring device, for example, a measuring device described in Patent Document 1 is known. The measuring device described in Patent Literature 1 includes a device main body and a measuring electrode, and stores a memory in which identification information for identifying the measuring electrode such as the type, model name, and serial number of the measuring electrode is written. It is provided inside a cable or connector for connecting the measurement electrode to the apparatus main body. The device main body reads the identification information from the memory on the measurement electrode side when the measurement electrode is first connected to the device main body, thereby identifying the measurement electrode connected to the device main body.

JP 2000-111506 A

  However, in the measurement device described in Patent Document 1 described above, the memory in which the identification information of the measurement electrode is written is provided in the measurement electrode or a cable or a connector for connecting the measurement electrode to the device main body. Since a component cost of the memory and a man-hour cost for writing the identification information of the measurement electrode into the memory occur, there is a possibility that the cost reduction of the measurement electrode may be hindered.

In addition, the provision of the memory in which the identification information of the measurement electrode is written may cause the following problems.
In order to secure the mounting area of the memory, it becomes difficult to reduce the size of the measurement electrode.
If the memory does not have radiation resistance, the reliability of data retention performance in a radiation environment is low.
As a specific example of the memory, an EEPROM which is a kind of the memory is known. The general-purpose EEPROM that is relatively easily available generally has an operating temperature range of “-40 ° C to 85 ° C” or “0 ° C to 70 ° C”, but the liquid temperature at which the measuring electrode is used is about 100 ° C. There is also a high temperature region, and the EEPROM may be unsuitable for such a high temperature region. An EEPROM having an operating temperature range corresponding to a high-temperature region of about 100 ° C. exceeding 85 ° C. is generally more expensive than a general-purpose EEPROM.
EEPROMs generally have an upper limit of the number of write operations of about 100,000 to 1,000,000 times, and have a limited memory cell data retention (unit of year). Is short.
The EEPROM requires hardware, for example, one power line, one common line, two communication lines, and the like because power and communication are required. In addition, the measurement circuit is often provided with a circuit isolation or separation process to avoid the influence of noise between an analog circuit for measurement to handle a weak signal and a digital circuit such as an EEPROM. In simplification such as common use of common lines, common lines are common to analog circuits and digital circuits, which is disadvantageous in terms of measurement reliability.
Since a certain amount of power is consumed at the time of writing to the memory, the battery life is shortened due to the power consumption of writing to the memory in a measuring device whose power source is a battery.
In a measuring device whose power supply is a commercial power supply, an abnormality occurs due to a power failure during writing to the memory.
The ROM area and the RAM area for storing firmware (software) for realizing the communication function between the EEPROM and the CPU are large.
There is also a new type of non-volatile memory, such as a ferroelectric non-volatile memory, which has improved some of the problems of the above-mentioned EEPROM, but the cost of the ferroelectric non-volatile memory is further increased as compared with the EEPROM. In addition, since the ferroelectric nonvolatile memory is also a semiconductor, the problems of the operating temperature range and the mounting area also exist in the ferroelectric nonvolatile memory.

  The present invention has been made in view of such circumstances, and can identify a sensor without having a memory in which identification information of the sensor is written in a sensor that can be attached to and detached from the main unit of the measurement device. It is an object to provide a measuring device and a main device of the measuring device.

(1) One embodiment of the present invention is a measurement device including a main body device and a sensor detachable from the main body device, wherein the sensor includes a measurement electrode and an identification resistance value for identifying the sensor. An identification circuit having the measurement device connected to the measurement electrode of the sensor connected to the main device by a signal line, and the identification circuit of the sensor connected to the main device. An identification voltage generation circuit that is connected by a signal line and generates an identification voltage corresponding to the identification resistance value of the identification circuit connected by the signal line; and, based on the identification voltage, that is connected to the main body device. A measurement unit comprising: a sensor identification unit that identifies a sensor; and a shutoff circuit that electrically shuts off the measurement unit from the identification circuit and the identification voltage generation circuit at a timing when the sensor is identified. It is a device.
(2) In one aspect of the present invention, the identification voltage generation circuit includes a resistor connected in series to the identification circuit, and an identification voltage application unit that applies an identification application voltage to the resistor. The measurement device according to the above (1), wherein the identification voltage is a resistance voltage division between a resistance value of the resistor and the identification resistance value.

(3) In one aspect of the present invention, in the main body device of the measuring device including the main body device and a sensor detachable from the main body device, a signal line is connected to a measurement electrode of the sensor connected to the main body device. The signal line is connected to the measurement unit connected by the signal line and the identification circuit of the sensor connected to the main body device, and generates an identification voltage according to the identification resistance value of the identification circuit connected by the signal line. An identification voltage generation circuit, a sensor identification unit that identifies the sensor connected to the main device based on the identification voltage, and a timing at which the identification of the sensor is performed. And a shutoff circuit for electrically shutting off the identification voltage generation circuit.
(4) In one aspect of the present invention, the identification voltage generation circuit includes a resistor connected in series to the identification circuit, and an identification voltage application unit that applies an identification application voltage to the resistor. The main unit of the measuring device according to the above (3), wherein the identification voltage is a resistance voltage division between a resistance value of the resistor and the identification resistance value.

  According to the present invention, it is possible to obtain an effect that a sensor can be identified without having a memory in which identification information of the sensor is written in a sensor that can be attached to and detached from the main body of the measuring device.

FIG. 1 is an overall schematic configuration diagram of a measurement device according to an embodiment of the present invention. It is a schematic structure figure showing an example of the electric composition of the measuring device concerning one embodiment of the present invention. It is a schematic structure figure showing an example of the functional composition of the measuring device concerning one embodiment of the present invention. FIG. 1 is a schematic configuration diagram illustrating an example of an electrical configuration of an identification voltage generation circuit according to an embodiment of the present invention. It is a figure showing an example of 1 composition of a sensor identification table concerning one embodiment of the present invention. 6 is a flowchart illustrating an example of a processing procedure of a main device of the measuring device according to the embodiment of the present invention. FIG. 6 is an overall schematic configuration diagram showing Modification Example 1 of the measurement device according to one embodiment of the present invention. FIG. 7 is an overall schematic configuration diagram showing Modification Example 2 of the measurement device according to one embodiment of the present invention. FIG. 11 is an overall schematic configuration diagram showing Modification Example 3 of the measurement device according to one embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is an overall schematic configuration diagram of a measuring device according to an embodiment of the present invention. 1, the measuring device 1 includes a sensor 10 and a main device 20. The sensor 10 includes a measurement electrode 11, a sensor-side circuit board 12, and a connector 13. The main body device 20 includes a main body side circuit board 21 and a connector 22.

  The sensor 10 is detachable from the main device 20. The connector 13 of the sensor 10 and the connector 22 of the main device 20 are a set of mating connectors. When the connector 13 of the sensor 10 and the connector 22 of the main body device 20 are fitted, the sensor side circuit board 12 of the sensor 10 and the main body side circuit board 21 of the main body device 20 are electrically connected.

  The measuring device 1 is a measuring device that can replace and use various sensors 10. As the sensor 10, for example, an electric conductivity electrode, an oxidation-reduction current measurement electrode (a dissolved oxygen electrode, a residual chlorine electrode, or the like) can be applied. The measuring device 1 can measure the measurement item corresponding to the sensor 10 connected to the main device 20 by replacing the sensor 10 connected to the main device 20.

  An identification circuit having an identification resistance value for identifying the sensor 10 is provided on the sensor-side circuit board 12 of the sensor 10. An identification voltage generating circuit for generating an identification voltage corresponding to the identification resistance value of the identification circuit of the sensor 10 connected to the main body device 20 is provided on the main body side circuit board 21 of the main body device 20; And a sensor identification unit that identifies the sensor 10 connected to the sensor 20. Main device 20 performs measurement processing of a measurement item corresponding to sensor 10 identified by the sensor identification unit.

  FIG. 2 is a schematic configuration diagram illustrating an example of an electrical configuration of the measurement device according to the present embodiment. 2, the sensor 10 includes a measurement electrode 11, a connector 13, and an identification circuit 31. The main unit 20 includes a connector 22, a CPU 32, an A / D (analog / digital) converter 33, a measurement circuit 34, a measurement voltage application circuit 35, a resistor Rx, switches SWa and SWb. Is provided.

  In the sensor 10, the measurement electrode 11 is connected to the connector terminal T1a and the connector terminal T3a of the connector 13. One end of the measurement electrode 11 is connected to the switch SWa of the main device 20 via the connector terminal T1b of the connector 22 of the main device 20 connected to the connector terminal T1a. The other end of the measurement electrode 11 is connected to the switch SWb of the main device 20 via the connector terminal T3b of the connector 22 of the main device 20 connected to the connector terminal T3a.

  When the switches SWa and SWb are on, one end of the measurement electrode 11 is connected to the measurement voltage application circuit 35 of the main device 20 and the other end is connected to the measurement circuit 34 of the main device 20. When the switches SWa and SWb are turned on, the measurement voltage application circuit 35 applies the measurement application voltage V3 to the measurement electrode 11, and the measurement circuit 34 outputs the measurement value to the A / D converter 33. You. The A / D converter 33 converts the value measured by the measuring circuit 34 into a digital value and outputs the digital value to the CPU 32 with a digital signal A. The CPU 32 acquires the measurement value of the measurement circuit 34 using the digital signal A. Thereby, the measurement of the measurement item corresponding to the sensor 10 can be performed.

  Examples of the measurement items of the present embodiment include measurement of electric conductivity corresponding to an electric conductivity sensor, measurement of residual chlorine corresponding to a residual chlorine sensor, measurement of dissolved oxygen corresponding to a dissolved oxygen sensor, and the like. In the measurement of residual chlorine, the measurement of dissolved oxygen, and in other cases, the measurement of dissolved hydrogen, the measurement of dissolved ozone, the measurement of hydrogen peroxide, and the like, are performed using polarography.

  The identification circuit 31 is formed on the sensor-side circuit board 12. The identification circuit 31 provided in the sensor 10 has an identification resistance value R1 for identifying the sensor 10. As the identification resistance value R1, a different value is set for each sensor 10 to be identified.

  As the identification resistance value R1, for example, a different value may be set for each type of the sensor 10. When a different identification resistance value R1 is set for each type of sensor 10, the identification resistance value R1 set in the identification circuit 31 of each sensor 10 is the same for sensors 10 of the same type.

  As the identification resistance value R1, for example, a different value may be set for each of the sensors 10. When a different identification resistance value R1 is set for each sensor 10, the identification resistance value R1 set in the identification circuit 31 of each sensor 10 is different even for the same type of sensor 10.

  The identification resistance value R1 can be set from approximately 0 ohm (Ω) to approximately infinity. By short-circuiting the terminals Tra and Trb of the identification circuit 31, the identification resistance value R1 can be set to approximately 0Ω. By opening the terminal Tra and the terminal Trb of the identification circuit 31, the identification resistance value R1 can be set to approximately infinity. By connecting a resistor having the identification resistance value R1 between the terminal Tra and the terminal Trb of the identification circuit 31, the identification resistance value R1 can be set.

  In the sensor 10, the terminal Tra of the identification circuit 31 is connected to the connector terminal T2a, and the terminal Trb of the identification circuit 31 is connected to the connector terminal T3a. The terminal Tra of the identification circuit 31 is connected to the ground of the main device 20 via the connector terminal T2b of the connector 22 of the main device 20 connected to the connector terminal T2a.

  The terminal Trb of the identification circuit 31 is connected to the A / D converter 33 and the resistor Rx of the main device 20 via the connector terminal T3b of the connector 22 of the main device 20 connected to the connector terminal T3a. Therefore, the identification circuit 31 of the sensor 10 connected to the main device 20 is connected to the connector terminal T3a of the sensor 10 for connecting the A / D converter 33 and the resistor Rx of the main device 20 and the main device 20. The connector terminal T3a of the sensor 10 for connecting the measurement electrode 11 of the sensor 10 to the measurement voltage application circuit 35 of the main device 20 is shared. Thereby, the number of pins accommodated in the connectors 13 and 22 for connecting the sensor 10 and the main body device 20 is reduced, so that the connectors 13 and 22 can be downsized.

  In the main device 20, the measurement voltage application circuit 35 is connected to one end of the switch SWb. The other end of the switch SWb is connected to the connector terminal T3b of the connector 22. The measurement voltage application circuit 35 applies the measurement application voltage V3 to the measurement electrode 11 via the connector terminal T3a of the sensor 10 connected to the connector terminal T3b when the switch SWb is on.

  Since the identification circuit 31 is connected to the connector terminal T3a of the sensor 10, the signal line connecting the measurement voltage application circuit 35 and the measurement electrode 11 is connected to the main unit via the identification circuit 31 (identification resistance value R1). 20 ground. For this reason, the measurement voltage application circuit 35 is capable of maintaining the measurement application voltage V3 in a state where its own output is connected to the ground of the main unit 20 via the identification circuit 31 (identification resistance value R1). This is a voltage application circuit having

  The measurement circuit 34 is connected to the A / D converter 33 and one end of the switch SWa. The other end of the switch SWa is connected to the connector terminal T1b of the connector 22. The measurement circuit 34 outputs the measured value to the A / D converter 33 when the switch SWa is on. The A / D converter 33 converts the value measured by the measuring circuit 34 into a digital value and outputs the digital value to the CPU 32 with a digital signal A. The CPU 32 acquires the measurement value of the measurement circuit 34 using the digital signal A.

  One end of the resistor Rx is connected to the connector terminal T3b of the connector 22 and the A / D converter 33. The other end of the resistor Rx is connected to the CPU 32. The CPU 32 applies the identification application voltage V1 to the resistor Rx. The A / D converter 33 detects the voltage V2 at one end of the resistor Rx, converts the detected voltage to a digital value, and outputs the digital value to the CPU 32 with a digital signal A. The CPU 32 acquires the detection voltage of the voltage V2 detected by the A / D converter 33 from the digital signal A.

  FIG. 3 is a schematic configuration diagram illustrating an example of a functional configuration of the measurement device according to the present embodiment. 3, the sensor 10 includes a measurement electrode 11 and an identification circuit 31. The identification circuit 31 of the sensor 10 has an identification resistance value R1 for identifying the sensor 10. The main device 20 includes an identification voltage generation circuit 51, an identification voltage detection unit 52, a sensor identification unit 53, a measurement unit (the measurement circuit 34, the measurement voltage application circuit 35), and a cutoff circuit (switches SWa and SWb). Is provided. The measurement unit includes a measurement circuit 34 and a measurement voltage application circuit 35. Hereinafter, these are referred to as measuring units 34 and 35. The cutoff circuit includes a switch SWa and a switch SWb. Hereinafter, these are referred to as cutoff circuits SWa and SWb.

  The identification voltage generation circuit 51 generates an identification voltage V2 according to the identification resistance value R1 of the identification circuit 31 of the sensor 10 connected to the main device 20. The identification voltage V2 corresponds to the voltage V2 shown in FIG. 2 described above.

  The identification voltage detector 52 detects the identification voltage V2. The identification voltage detection unit 52 notifies the sensor identification unit 53 of a detection voltage V2d obtained by detecting the identification voltage V2. The identification voltage detector 52 corresponds to the A / D converter 33.

  The sensor identification unit 53 identifies the sensor 10 connected to the main device 20 based on the detection voltage V2d notified from the identification voltage detection unit 52. The sensor identification unit 53 includes a sensor identification table 54. The sensor identification table 54 stores information that associates the detection voltage V2d with the sensor 10. The sensor identification unit 53 identifies the sensor 10 corresponding to the detection voltage V2d notified from the identification voltage detection unit 52 using the sensor identification table 54. The sensor identification unit 53 corresponds to the CPU 32. The function of the sensor identification unit 53 is realized by the CPU 32 executing a computer program for realizing the function of the sensor identification unit 53.

  The sensor identification section 53 controls the cutoff circuits SWa and SWb. The cutoff circuits SWa and SWb electrically cut off the measuring units 34 and 35 from the discrimination circuit 31 and the discrimination voltage generation circuit 51 at the timing when the sensor 10 is discriminated. Specifically, at the timing when the identification of the sensor 10 is performed, the sensor identification unit 53 turns off the switches SWa and SWb. Thereby, when the identification of the sensor 10 is performed, it is possible to prevent the measuring units 34 and 35 from having an electrical influence on the identification of the sensor 10. When the switches SWa and SWb are off, the circuit shown in FIG. 4 is configured.

FIG. 4 is a schematic configuration diagram illustrating an example of an electrical configuration of the identification voltage generation circuit according to the present embodiment. In FIG. 4, the identification voltage generation circuit 51 includes a resistor Rx connected in series to an identification circuit 31 having an identification resistance value R1, and a CPU 32 (identification voltage application unit) that applies an identification application voltage V1 to the resistor Rx. And. In the identification voltage generation circuit 51 shown in FIG. 4, the identification voltage V2 is a resistance voltage division between the resistance value rx of the resistor Rx and the identification resistance value R1, and is expressed by the following equation (1).
V2 = V1 × (R1 ÷ (rx + R1)) (1)

  In the present embodiment, the CPU 32 serving as the identification voltage application unit applies the reference voltage for applying the identification application voltage V1, and the A / D converter 33 serving as the identification voltage detection unit detects the identification voltage V2. And the same reference voltage. As a result, the detection voltage V2d resulting from the detection of the identification voltage V2 by the A / D converter 33 becomes highly accurate for the CPU 32. This contributes to an improvement in identification accuracy when the CPU 32 serving as the sensor identification unit 53 identifies the sensor 10 connected to the main device 20 based on the detection voltage V2d.

  FIG. 5 is a diagram illustrating a configuration example of the sensor identification table according to the embodiment. 5, the sensor identification table 54 stores information that associates the detection voltage V2d of the identification voltage V2 with the type of the sensor 10. In the example of FIG. 5, the sensor identification table 54 stores the detected voltage V2d, the type of the sensor 10, and data such as calibration data in association with each other.

  The detection voltage V2d stored in the sensor identification table 54 corresponds to the identification voltage V2 generated by the identification voltage generation circuit 51 according to the identification resistance value R1 of the identification circuit 31 of the target sensor 10 identified by the detection voltage V2d. To be determined. In the identification voltage generation circuit 51 shown in FIG. 4, the detection voltage V2d stored in the sensor identification table 54 is determined so as to correspond to the identification voltage V2 represented by the above equation (1).

  The sensor identification unit 53 searches the sensor identification table 54 using the detection voltage V2d notified from the identification voltage detection unit 52 as a search key. The sensor identification unit 53 determines that the type of the sensor 10 found as a result of the search is the type of the sensor 10 connected to the main device 20. The main device 20 (CPU 32) performs the measurement process using the calibration data corresponding to the type of the sensor 10 determined by the sensor identification unit 53.

  FIG. 6 is a flowchart illustrating an example of a processing procedure of the main device of the measuring device according to the present embodiment. The processing procedure shown in FIG. 6 is started when the power of the main body device 20 is turned on and the CPU 32 is started, and the functions of the sensor identification unit 53 and the like are realized by the CPU 32 executing the computer program.

(Step S1) The sensor identification unit 53 turns off the switches SWa and SWb.

(Step S2) The applied voltage for identification (CPU 32) applies the applied voltage V1 for identification to the resistor Rx.

(Step S3) The sensor identification unit 53 reads the detection voltage V2d notified from the identification voltage detection unit 52.

(Step S4) The sensor identification unit 53 identifies the sensor 10 using the sensor identification table 54.

(Step S5) The sensor identification unit 53 turns on the switches SWa and SWb.

(Step S6) The CPU 32 performs a measurement process using the calibration data of the sensor 10 as the identification result of the sensor identification unit 53. Thereby, the measurement of the measurement item corresponding to the sensor 10 connected to the main device 20 can be performed.

  According to the above-described embodiment, the sensor 10 only needs to include the identification circuit 31 having the identification resistance value R1 for identifying the sensor 10, and does not need to include a memory. In general, resistors are inexpensive compared to memories, so that the effect of reducing the cost of the sensor 10 can be obtained. Further, as compared with the memory, the effect of contributing to downsizing, improvement of reliability, power saving, extension of life, and the like can be obtained.

  Further, according to the above-described embodiment, the signal line connecting the measurement electrode 11 of the sensor 10 connected to the main device 20 and the measurement unit (measurement voltage application circuit 35), the identification circuit 31 of the sensor 10, The signal line connecting the identification voltage generation circuit 51 and the identification voltage generation circuit 51 is shared. Then, at the timing when the identification of the sensor 10 is performed, the measurement unit (the measurement circuit 34 and the measurement voltage application circuit 35) is electrically disconnected from the identification circuit 31 and the identification voltage generation circuit 51. Thereby, when the identification of the sensor 10 is performed, it is possible to prevent the measuring units 34 and 35 from having an electrical influence on the identification of the sensor 10, and the connector 13 for connecting the sensor 10 and the main unit 20. By reducing the number of accommodating pins of the connector 22, the size of the connectors 13 and 22 can be reduced.

  In the measurement items using polarography (for example, measurement of residual chlorine, measurement of dissolved oxygen, and the like), the identification voltage V2 is set so as to be in a specific region (a constant voltage range) of the measurement application voltage V3. Good. This is because, in a measurement item using a polarograph, the diffusion current becomes flat (plateau region) in the region of the applied voltage for measurement V3, so that even if the applied voltage V3 for measurement slightly fluctuates, the diffusion current depending on the concentration becomes large. Making use of the fact that the identification voltage V2 is in the region of the applied voltage for measurement V3 (a constant voltage range) where the diffusion current becomes flat, the measurement can be performed immediately after the identification of the sensor 10. Because.

  As described above, the embodiments of the present invention have been described in detail with reference to the drawings. However, the specific configuration is not limited to the embodiments, and includes a design change or the like without departing from the gist of the present invention.

  For example, in the above-described embodiment, the main device 20 and the sensor 10 may be configured to be connected via a cable. FIGS. 7, 8, and 9 are general schematic diagrams showing a modification of the measuring device according to the embodiment of the present invention. 7, 8 and 9, parts corresponding to FIG. 1 are denoted by the same reference numerals.

(Modification 1)
FIG. 7 is an overall schematic configuration diagram showing Modification Example 1 of the measurement device according to one embodiment of the present invention. In the measuring device 1 shown in FIG. 7, the main device 20 includes a cable 70, and a connector 22 is attached to a distal end of the cable 70. The sensor 10 is configured to be attachable to and detachable from the main unit 20 when the connector 13 and the connector 22 of the cable 70 are fitted or disconnected.

(Modification 2)
FIG. 8 is an overall schematic configuration diagram showing Modification Example 2 of the measurement device according to one embodiment of the present invention. In the measuring device 1 shown in FIG. 8, the sensor 10 includes a cable 71, and a connector 13 is attached to a tip of the cable 71. The sensor 10 is configured so that the connector 13 of the cable 71 and the connector 22 of the main body device 20 are fitted or detached from each other, so that the sensor 10 can be attached to and detached from the main body device 20.

(Modification 3)
FIG. 9 is an overall schematic configuration diagram showing Modification Example 3 of the measuring device according to one embodiment of the present invention. In the third modification, the cable 72 is provided separately from the main device 20 and the sensor 10. At one end of the cable 72, a connector 22a that fits with the connector 22 of the main device 20 is attached. At the other end of the cable 72, a connector 13a that fits with the connector 13 of the sensor 10 is attached. The sensor 10 is configured to be attachable / detachable to / from the main unit 20 by connecting or disconnecting the main unit 20 via the cable 72.

  According to Modifications 1, 2, and 3 described above, the distance between main device 20 and sensor 10 can be increased.

DESCRIPTION OF SYMBOLS 1 ... Measurement apparatus, 10 ... Sensor, 11 ... Measurement electrode, 13, 13a, 22,22a ... Connector, 20 ... Main body device, 31 ... Identification circuit, 32 ... CPU, 33 ... A / D converter, 34 ... Measuring circuit (Measurement unit), 35: measurement voltage application circuit (measurement unit), 51: identification voltage generation circuit, 52: identification voltage detection unit, 53: sensor identification unit, 54: sensor identification table, 70, 71, 72 ... cable , Rx: resistor, SWa, SWb: switch (cutoff circuit)

Claims (4)

In a measuring device including a main body device and a sensor detachable from the main body device,
The sensor is
A measuring electrode,
An identification circuit having an identification resistance value for identifying the sensor,
The main unit includes:
A measurement unit connected to the measurement electrode of the sensor connected to the main unit by a signal line,
An identification voltage generation circuit that is connected to the identification circuit of the sensor connected to the main body device by the signal line and generates an identification voltage according to the identification resistance value of the identification circuit connected by the signal line;
Based on the identification voltage, a sensor identification unit that identifies the sensor connected to the main device,
At a timing at which the identification of the sensor is performed, a disconnection circuit that electrically disconnects the measurement unit from the identification circuit and the identification voltage generation circuit,
Measuring device. The identification voltage generation circuit,
A resistor connected in series with the identification circuit;
An identification voltage application unit that applies an identification application voltage to the resistor,
The identification voltage is a resistance divided between the resistance value of the resistor and the identification resistance value,
The measuring device according to claim 1. In the main body device of the measuring device including a main body device and a sensor that is detachable from the main body device,
A measurement unit connected to the measurement electrode of the sensor connected to the main unit by a signal line,
An identification voltage generation circuit that is connected to the identification circuit of the sensor connected to the main body device by the signal line and generates an identification voltage according to an identification resistance value of the identification circuit connected by the signal line;
Based on the identification voltage, a sensor identification unit that identifies the sensor connected to the main device,
At a timing at which the identification of the sensor is performed, an interruption circuit that electrically disconnects the measurement unit from the identification circuit and the identification voltage generation circuit,
The main device of the measuring device comprising: The identification voltage generation circuit,
A resistor connected in series with the identification circuit;
An identification voltage application unit that applies an identification application voltage to the resistor,
The identification voltage is a resistance divided between the resistance value of the resistor and the identification resistance value,
A main device of the measuring device according to claim 3.

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