JP6542094B2 - Contact determination device and measurement device - Google Patents

Description

  The present invention can determine the contact state between the contact terminal and the to-be-contacted portion in a measuring device that measures the amount to be measured in a state where a DC signal is supplied to the measurement object via the contact terminal brought into contact with the to-be-contacted portion The present invention relates to a contact determination device and a measurement device including the contact determination device.

  As a measuring apparatus of this type, a two-terminal circuit element measuring apparatus (hereinafter, also simply referred to as “measuring apparatus”) disclosed in Patent Document 1 below is known. This measuring apparatus includes an ammeter, a DC voltage generating circuit that generates a voltage obtained by superimposing an AC voltage on a DC voltage, a CPU, and the like, and is configured to be able to measure the insulation resistance of a measurement target (DUT). Here, when the contact state between the cable supplying the voltage to the object to be measured and the object to be measured is poor, the insulation resistance can not be measured correctly, so the measuring device determines the contact state between the cable and the object to be measured. Functions are installed. In this case, when the contact state between the cable and the object to be measured is good, the AC component of the current flows through the capacity of the object to be measured, and when the contact state is defective, neither the DC component nor the AC component of the current flows. In the measuring device, when both the DC component and the AC component of the current measured by the ammeter are 0 A, the contact state is determined to be defective, and when the AC component of the current is not 0 A, the contact state is determined to be good.

JP-A-2004-245584 (pages 6-7, FIG. 1)

  However, the above-described measuring apparatus has the following problems. That is, in the above-mentioned measuring device, a coaxial cable (shield wire) which has a core wire (the 1st conductor) and a shield (the 2nd conductor) is used as a cable which supplies voltage to a measuring object. In this case, when the cable length of the coaxial cable is longer than the specified value, the capacity between the core wire and the shield increases, so when the AC component of the current measured by the ammeter is the specified value As a result of being smaller than the alternating current component measured in the above, there is a possibility that the contact state may be erroneously determined. In addition, when the cable length of the coaxial cable is shorter than the specified value, the capacity between the core wire and the shield becomes smaller, so when the cable length of the alternating current component measured by the ammeter is the specified value. As a result of being larger than the AC component to be measured, there is a possibility that the contact state may be erroneously determined. Therefore, when using a coaxial cable whose cable length is different from the specified value, it is necessary to readjust the sensitivity of the amplifier and the amplitude of the AC voltage according to the cable length in the above-mentioned measuring device, which makes the operation complicated. There is a problem that

  The present invention has been made in view of the above problems, and even when the length of the shield wire is changed, the contact state between the contact terminal and the to-be-contacted portion to be measured without performing a complicated operation. A main object of the present invention is to provide a contact determination device and a measurement device capable of accurately determining the quality.

  In order to achieve the above object, the contact determination device according to claim 1 comprises a core wire and a shield wire having a shield surrounding the core wire, the first contact terminal connected to the tip of the core wire being one contact target in the measurement object A second contact terminal connected to the tip of the lead wire and in contact with the other contact portion of the object to be measured, and the DC signal from the DC signal source is transmitted through the core wire and the lead wire. A contact determination device capable of determining a contact state between each contact terminal and each contact portion in a measurement device that measures an amount to be measured of the measurement target in a state of being supplied to the measurement target, A first circuit connecting the base end and one electrode of the DC signal source; a second circuit connecting the base end of the shield and the one electrode; the base end of the shield and the one With the electrodes A third circuit connected in parallel to the second circuit, and a detection circuit for detecting a physical quantity capable of determining the contact state, the first circuit comprising a first conversion element for current-voltage conversion The second circuit includes a variable capacitance element connected in series and a second conversion element for current-voltage conversion, and the third circuit is an AC signal source that outputs an AC signal for determining the contact state. The detection circuit detects, as the physical quantity, a voltage difference between a voltage subjected to current-voltage conversion by the first conversion element and a voltage subjected to current-voltage conversion by the second conversion element.

  A contact determination apparatus according to a second aspect is the contact determination apparatus according to the first aspect, wherein the alternating current signal source is configured to be capable of changing the frequency of the alternating current signal.

  The contact determination apparatus according to claim 3 is the contact determination apparatus according to claim 1 or 2, wherein the voltage difference output from the detection circuit does not become 0 V within the adjustment range of the capacitance of the variable capacitance element. Is provided with a notification unit that notifies that.

  The measuring device according to claim 4 includes the contact determination device according to any one of claims 1 to 3, the DC signal source, and an ammeter provided in the first circuit, and the ammeter The measured amount of the measurement target is measured based on the current value detected by

  In the contact determination device according to claim 1 and the measurement device according to claim 4, a first circuit having a first conversion element and connecting a core wire of a shield wire and a DC signal source, a variable capacitance element and a second conversion A second circuit having an element and connecting a shield of the shield wire to a DC signal source, an AC signal source outputting an AC signal, and a third circuit connected in parallel to the second circuit; And a detection circuit that detects a voltage difference between the voltage converted from current to voltage by the element and the voltage converted from current to voltage by the second conversion element. Therefore, according to the contact determination device and the measurement device, the capacitance of the variable capacitance element is set such that the voltage difference output from the detection circuit becomes 0 V in a state where each contact terminal is separated from each contact portion to be measured. After adjustment, each contact terminal can be brought into contact with each contact portion of the measurement object, without being affected by the current flowing through the capacitance of the shield wire. The quality of the contact state with the unit can be accurately determined. Further, according to the contact determination device and the measurement device, the capacitance of the variable capacitance element can be equalized to the capacitance of the shield wire by adjusting the capacitance of the variable capacitance element before the determination of the contact state. Even if the shield wire is changed and the capacitance of the shield wire is changed, it is possible to reliably prevent a situation in which the determination of the contact state is affected by the change of the shield wire without performing complicated work, and the contact state It is possible to accurately determine the quality of the

  Further, according to the contact determination device of claim 2 and the measuring device of claim 4, the alternating current signal source is configured so as to be able to change the frequency of the alternating current signal, so that, for example, other measuring devices of the same type. Each AC signal output from each AC signal source by making the frequency of the AC signal output from each AC signal source different in each measurement apparatus different from each other in a measurement environment in which the used measurement is simultaneously performed in adjacent places It is possible to reliably prevent a situation in which the adjustment of the capacitance of the variable capacitance element and the determination of the contact state become inaccurate due to the interference between the two.

  Further, according to the contact determination device of claim 3 and the measurement device of claim 4, when the voltage difference output from the detection circuit does not become 0 V within the adjustment range of the capacitance of the variable capacitance element By providing the notification unit for notifying, for example, when it is intended to perform measurement using a shielded wire whose capacity is too large (too long), the user can be reliably notified of that. Therefore, according to the contact determination device and the measurement device, the determination of the contact state between each contact terminal and each contact portion can be accurately performed by performing measurement using a shield wire having a large capacity (too large). It is possible to reliably prevent such a situation that can not be performed or the measured amount of the measurement object can not be accurately measured due to the influence of the capacity of the shield wire.

FIG. 2 is a block diagram showing the configuration of a resistance measuring device 1; FIG. 2 is a block diagram showing a circuit configuration of a measurement unit 2; FIG. 5 is a first explanatory view for explaining a measurement method using the resistance measurement device 1; FIG. 5 is a second explanatory view illustrating a measurement method using the resistance measurement device 1;

  Hereinafter, embodiments of a contact determination device and a measurement device according to the present invention will be described with reference to the attached drawings.

  First, the configuration of the resistance measuring device 1 shown in FIG. 1 will be described. The resistance measuring device 1 is an example of a measuring device, and is configured to be able to measure an insulation resistance Ri (an example of a measured amount) of the measuring object 50. Specifically, as shown in the figure, the resistance measuring device 1 is configured to include a measuring unit 2, an operation unit 3, a display unit 4 and a processing unit 5.

  As shown in FIG. 2, the measurement unit 2 includes a DC power supply 21 (DC signal source), an ammeter 22, inductors 23a and 23b, a variable capacitor 24 (variable capacitance element), resistors 25a, 25b and 25c, and an AC power supply 26 An AC signal source and a differential amplifier 27 (detection circuit) are provided. The inductors 23a and 23b, the variable capacitor 24, the resistors 25a and 25b, the AC power supply 26, and the differential amplifier 27 constitute a contact determination device.

  In addition, a connection (not shown) for connecting the shield wire 60 and the conducting wire 70 (see FIG. 2) for supplying the measuring object 50 with an alternating current voltage (alternating current signal) and a direct current voltage (direct current signal). A terminal is provided. In this case, as shown in the figure, the shield wire 60 is constituted by a coaxial cable including a core wire 61 and a shield 62 disposed so as to surround the core wire 61 via an insulator. Further, a contact terminal 63 (first contact terminal) to be brought into contact with the to-be-contacted portion 51 of the measurement target 50 is connected to the tip end portion 61 a of the core wire 61 in the shield wire 60. A connection terminal (not shown) connectable to the connection terminal of the measurement unit 2 is connected to the base end 61 b of the core wire 61 and the base end 62 b of the shield 62 in the shield wire 60. In addition, a contact terminal 71 (second contact terminal) to be brought into contact with the to-be-contacted portion 51 of the measurement object 50 is connected to the tip end portion 70a of the lead 70. Connection terminals (not shown) connectable to the connection terminals are connected.

  The DC power supply 21 outputs a DC voltage (DC signal) for measuring the insulation resistance according to the control of the processing unit 5. Further, as shown in FIG. 2, the negative electrode 21a (one electrode) of the DC power supply 21 is a base end portion of the core wire 61 in the shield wire 60 via the first circuit Pc1, the second circuit Pc2 and the third circuit Pc3. The positive electrode 21 b (the other electrode) of the direct current power source 21 is connected to the proximal end 70 b of the conducting wire 70. In this case, as shown in the figure, the first circuit Pc1 includes the ammeter 22, the inductor 23a, and the resistor 25a, and the second circuit Pc2 includes the inductor 23b, the variable capacitor 24, and the resistor 25b. The third circuit Pc3 is configured to include the resistor 25c and the AC power supply 26.

  As shown in FIG. 2, the ammeter 22 is provided in a first circuit Pc1 connecting the base end 61b of the core wire 61 in the shield wire 60 and the negative electrode 21a of the DC power supply 21 and a current I1 flowing in the first circuit Pc1. The current value (see FIG. 3) is detected.

  The inductor 23a is connected in series to the ammeter 22 in the first circuit Pc1, as shown in FIG. The inductor 23a functions as a first conversion element (for current-voltage conversion) for converting a current flowing through the first circuit Pc1 into a voltage, and also has a function of protecting the ammeter 22 from high frequency. In the resistance measuring device 1, as an example, a 1000 μH inductor is used as the inductor 23a.

  The resistor 25a is a resistor for protecting the ammeter 22. As shown in FIG. 2, the resistor 25a is connected in series to the ammeter 22 and the inductor 23a in the first circuit Pc1. In this case, in the resistance measuring device 1, a resistor 25 a of 1 kΩ is used as an example.

  The variable capacitor 24 is a capacitor whose capacitance can be adjusted, and is provided in a second circuit Pc2 connecting the base end 62b of the shield 62 in the shield wire 60 and the negative electrode 21a of the DC power supply 21 as shown in FIG. ing.

  The inductor 23b is connected in series to the variable capacitor 24 in the second circuit Pc2, as shown in FIG. In this case, the inductor 23b functions as a second conversion element (for current-voltage conversion) for converting the current flowing through the second circuit Pc2 into a voltage. In the resistance measuring device 1, an inductor 23b of 1000 μH, which is the same as the inductor 23a in the first circuit Pc1, is used.

  The resistor 25b is a resistor for adjustment to make the overall resistance value of the second circuit Pc2 equal to the overall resistance value of the first circuit Pc1, and the resistor 25b is a resistor for adjusting the variable capacitor 24 and the inductor 23b in the second circuit Pc2. In between, it is connected in series to the variable capacitor 24 and the inductor 23b. In this case, in the resistance measuring device 1, the same resistance 25b of 1 kΩ as the resistance 25a in the first circuit Pc1 is used.

  As shown in FIG. 2, the AC power supply 26 is provided in a third circuit Pc3 parallel to the second circuit Pc2 by connecting the base end 62b of the shield 62 in the shield wire 60 and the negative electrode 21a of the DC power supply 21. . The AC power supply 26 outputs an AC voltage (AC signal for contact state determination) under the control of the processing unit 5. Further, the AC power supply 26 is configured to be capable of changing the frequency of the AC voltage according to the control of the processing unit 5. In this case, the resistance measuring device 1 adopts a configuration in which the frequency of the AC power supply 26 is changed by selecting any one frequency from the plurality of preset frequencies by the operation of the operation unit 3 There is.

  The resistor 25 c is a termination resistor for terminating (protecting) the AC power supply 26, and is connected in parallel to the AC power supply 26 as shown in FIG. 2. In this case, in the resistance measuring device 1, a resistor 25 c of 50Ω is used as an example.

  The differential amplifier 27 is, as shown in FIG. 2, a voltage V1 at a position A1 between the inductor 23a and the resistor 25a in the first circuit Pc1 (voltage subjected to current-voltage conversion by the inductor 23a), and It outputs (detects) a voltage difference Vs (a physical quantity capable of determining a contact state) between a voltage V2 at a position A2 between the inductor 23b and the resistor 25b (a voltage subjected to current-voltage conversion by the inductor 23b).

  The operation unit 3 includes various switches, and outputs an operation signal when these are operated. The display unit 4 displays various values and character information according to the control of the processing unit 5. Specifically, the display unit 4 displays the value of the insulation resistance Ri measured by the processing unit 5, the value of the voltage difference Vs output from the differential amplifier 27 of the measurement unit 2, and character information described later, etc. .

  The processing unit 5 executes various processes in accordance with the operation signal output from the operation unit 3. Specifically, the processing unit 5 measures the insulation resistance Ri of the object to be measured 50 based on the current value detected by the ammeter 22 of the measurement unit 2 and the voltage value of the DC voltage output from the DC power supply 21; The value of the insulation resistance Ri is displayed on the display unit 4. The processing unit 5 functions as a notification unit together with the display unit 4 and indicates that the voltage difference Vs output from the differential amplifier 27 does not become 0 V within the adjustment range of the capacitance of the variable capacitor 24 of the measurement unit 2. Text information is displayed on the display unit 4.

  Next, a method of measuring the insulation resistance Ri of the object to be measured 50 using the resistance measuring device 1 and the operation of the resistance measuring device 1 at that time will be described with reference to the drawings.

  Prior to measurement, the capacity adjustment of the variable capacitor 24 in the measurement unit 2 is performed. In this capacity adjustment, first, the operation unit 3 is operated to select and set the frequency of the AC voltage output from the AC power supply 26 from among a plurality of preset frequencies.

  Next, as shown in FIG. 3, in a state in which the contact terminal 63 connected to the shield wire 60 is separated from the to-be-contacted portion 51 of the measurement target 50, the operation unit 3 is operated to operate the AC power supply 26 of the measurement unit 2. Direct the output of AC voltage by. Subsequently, the processing unit 5 controls the AC power supply 26 according to the operation signal output from the operation unit 3 to output an AC voltage.

  In this case, in this state, as shown in FIG. 3, since the contact terminal 63 is separated from the to-be-contacted portion 51 of the measurement target 50, no alternating voltage is supplied to the to-be-contacted portion 51. There is no current flow. On the other hand, since there is a capacitance (hereinafter, this capacitance is also referred to as “capacitance C1”) between the core wire 61 and the shield 62, the first circuit Pc1 has a current according to the capacitance C1 by the output of the alternating voltage. I1 flows. Further, due to the output of the alternating voltage, a current I2 flows in the second circuit Pc2 according to the capacitance of the variable capacitor 24 (hereinafter, this capacitance is also referred to as "capacitance C2"). A combined current I3 of the currents I1 and I2 flows through the third circuit Pc3.

  The differential amplifier 27 outputs a voltage difference Vs between the voltage V1 at the position A1 current-voltage converted by the inductor 23a and the voltage V2 at the position A2 current-voltage converted by the inductor 23b. Further, the processing unit 5 causes the display unit 4 to display the value of the voltage difference Vs.

  In this case, when the voltage difference Vs is not 0 V (that is, when the voltages V1 and V2 are different), the voltage difference Vs is 0 V while looking at the value of the voltage difference Vs displayed on the display unit 4 The capacitance C2 of the variable capacitor 24 is adjusted. Here, in the resistance measuring device 1, the inductance of the inductor 23a in the first circuit Pc1 and the inductance of the inductor 23b in the second circuit Pc2 are equal to each other, and the resistance value of the resistor 25a in the first circuit Pc1 and the resistance in the second circuit Pc2 Since the resistances 25b are equal to each other, when the capacitance C1 of the shield wire 60 and the capacitance C2 of the variable capacitor 24 are equal, the current I1 flowing through the first circuit Pc1 and the current I2 flowing through the second circuit Pc2 become equal. As a result, the voltages V1 and V2 become equal, and the voltage difference Vs becomes 0V. That is, when the voltage difference Vs becomes 0 V, the capacitance C1 of the shield wire 60 and the capacitance C2 of the variable capacitor 24 become equal.

  Then, the operation unit 3 is operated to instruct stop of the output of the AC voltage, and in response to this, the processing unit 5 controls the AC power supply 26 to stop the output of the AC voltage. Thus, the adjustment of the capacitance of the variable capacitor 24 is completed.

  When the voltage difference Vs does not become 0 V in the capacity adjustment range of the variable capacitor 24 in the capacity adjustment of the variable capacitor 24, the processing unit 5 causes the display unit 4 to display character information indicating that. At this time, the processing unit 5 causes the display unit 4 to display the capacitance C2 of the variable capacitor 24 as a reference value. When such information is displayed on the display unit 4, it means that the capacitance C1 of the shield line 60 is too large (that is, the shield line 60 is too long). At this time, it is not possible to accurately determine whether the contact state between the contact terminals 63 and 71 and the to-be-contacted portion 51 described later is correct or not, and when measuring the insulation resistance Ri of the object 50 to be measured There is a possibility that the insulation resistance Ri can not be accurately measured due to the influence of the capacitance C1. Therefore, when such information is displayed on the display unit 4, the shield wire 60 is replaced with a short one, and the capacity adjustment of the variable capacitor 24 is performed again.

  Subsequently, the measurement of the insulation resistance Ri in the measurement target 50 is started. First, as shown in FIG. 4, an operation of bringing the contact terminals 63 and 71 into contact with the respective contact portions 51 of the measuring object 50 is performed. Then, the operation unit 3 is operated to instruct determination of the contact state between the contact terminals 63 and 71 and the to-be-contacted portion 51. Subsequently, the processing unit 5 controls the AC power supply 26 in accordance with the operation signal output from the operation unit 3 to output an AC voltage.

  In this case, as shown in FIG. 4, when the contact terminals 63 and 71 are in contact with the respective contact portions 51 of the measuring object 50, the current I1 flows even through the capacitance C3 of the measuring object 50. The current value of the current I1 flowing to the circuit Pc1 and the current value of the current I2 flowing to the second circuit Pc2 will be different, and the voltage V1 at the position A1 and the voltage V2 at the position A2 will be different values. It is not a value. Therefore, when the value of the voltage difference Vs other than 0 V is displayed on the display unit 4, the contact terminals 63 and 71 are in contact with the respective contact portions 51 of the measurement target 50 (the contact state is good). It can be grasped.

  On the other hand, as shown in FIG. 3, when at least one of the contact terminals 63 and 71 (only the contact terminal 63 in the same figure) is not in contact with each contact portion 51 of the measuring object 50 As described in the capacity adjustment, the current I1 flowing in the first circuit Pc1 and the current I2 flowing in the second circuit Pc2 become equal, and as a result, the voltages V1 and V2 become equal, and the voltage difference Vs becomes 0V. Therefore, when the value of the voltage difference Vs of 0 V is displayed on the display unit 4, it is understood that the contact terminals 63 and 71 are not in contact with the respective contact portions 51 of the measuring object 50 (the contact state is defective). can do. At this time, the operation of bringing the contact portions 51 of the measuring object 50 into contact with each other is performed again.

  In the resistance measuring device 1, the measuring unit 2 is configured as described above, and the capacitance C2 of the variable capacitor 24 is adjusted to equalize the capacitance C1 of the shield wire 60 and the capacitance C2 of the variable capacitor 24 prior to the determination of the contact state. Thus, as described above, the quality of the contact state between the contact terminals 63 and 71 and the respective contact portions 51 of the measuring object 50 can be accurately determined without being affected by the current flowing through the capacitance C1 of the shield wire 60. It is possible to determine. Further, in the resistance measuring device 1, since the capacitance C2 and the capacitance C1 of the shield wire 60 are made equal prior to the determination of the contact state, it is assumed that the capacitance C1 of the shield wire 60 is changed by changing the shield wire 60. Also, since the correctness of the determination of the contact state is not affected by the change of the shield wire 60, the determination of the contact state can be performed correctly.

  Further, in the resistance measuring device 1, since the frequency of the AC voltage output from the AC power supply 26 can be changed, the measurement using the other resistance measuring device 1 of the same type can be simultaneously performed at adjacent places. In the measurement environment, the frequencies of the AC voltages output from the AC power supplies 26 in the resistance measuring devices 1 are made different from each other, so that the capacity adjustment of the variable capacitor 24 is caused by the interference between the AC voltages output from the AC power supplies 26. In addition, it is possible to reliably prevent a situation in which the determination of the contact state is incorrect.

  Next, when it is determined that the contact state between the contact terminals 63 and 71 and the to-be-contacted portion 51 is good, the operation unit 3 is operated to instruct the end of the determination of the contact state, and subsequently, the operation unit 3 is Operate to instruct to perform measurement. Next, the processing unit 5 controls the AC power supply 26 in accordance with the operation signal output from the operation unit 3 to stop the output of the AC voltage, and then controls the DC power supply 21 to output the DC voltage. At this time, a DC voltage is supplied to the respective contact portions 51 of the object 50 to be measured via the contact terminals 63 and 71. Along with this, the current I11 (see FIG. 4) according to the insulation resistance Ri of the measurement target 50 flows through the first circuit Pc1, and the ammeter 22 detects the current I11.

  Next, the processing unit 5 measures the insulation resistance Ri of the object to be measured 50 based on the current value of the current I11 detected by the ammeter 22 and the voltage value of the DC voltage output from the DC power supply 21. The value of the insulation resistance Ri is displayed on the display unit 4. Thus, the measurement of the insulation resistance Ri is completed.

  In this case, when the insulation resistance Ri is equal to or higher than a predetermined threshold value, the insulation state of the object to be measured 50 is determined to be good. When the insulation resistance Ri is less than the threshold value, the insulation state of the object to be measured 50 is defective. judge. In the resistance measuring device 1, as described above, since the quality of the contact state between the contact terminals 63 and 71 and the respective contact portions 51 of the measurement object 50 can be accurately determined, when the contact state is good Only the measurement of the insulation resistance Ri can be performed. For this reason, in this resistance measuring device 1, as a result of measuring the insulation resistance Ri when the contact state is defective, the insulation resistance Ri of the object 50 to be measured is actually small (despite the insulation state being defective). The insulation resistance Ri is measured as a large value, which makes it possible to reliably prevent the insulation state from being erroneously determined as a good measurement target 50 of a failure.

  As described above, in the contact determination device and the resistance measurement device 1, the first circuit Pc 1 having the inductor 23 a and connecting the core wire 61 of the shield wire 60 to the DC power supply 21, the variable capacitor 24 and the inductor 23 b A third circuit Pc3 having a second circuit Pc2 connecting the shield 62 of the shield wire 60 and the DC power supply 21 and an AC power supply 26 outputting an AC voltage and connected in parallel to the second circuit Pc2 A differential amplifier 27 is provided to detect a voltage difference Vs between the voltage V1 at the position A1 in Pc1 and the voltage V2 at the position A2 in the second circuit Pc2. Therefore, according to the contact determination device and the resistance measurement device 1, the voltage difference Vs output from the differential amplifier 27 becomes 0 V in a state in which the contact terminals 63 and 71 are separated from the contacted portion 51 of the measurement target 50 As described above, after the capacitance C2 of the variable capacitor 24 is adjusted, the contact terminals 63 and 71 are brought into contact with the respective contact portions 51 of the measurement target 50, whereby the influence of the current flowing through the capacitance C1 of the shield wire 60 It is possible to accurately determine the quality of the contact state between the contact terminals 63 and 71 and the respective to-be-contacted portions 51 of the measuring object 50 without receiving the problem. Further, according to the contact determination device and the resistance measurement device 1, it is possible to equalize the capacitance C2 and the capacitance C1 of the shield wire 60 by adjusting the capacitance C2 of the variable capacitor 24 before performing the determination of the contact state. Therefore, even if the capacity C1 of the shield wire 60 is changed by changing the shield wire 60, it is possible to ensure that the change in the shield wire 60 affects the determination of the contact state without performing complicated work. It can prevent and can judge correctly the quality of a contact state.

  Further, according to the contact determination device and the resistance measuring device 1, by configuring the AC power supply 26 so that the frequency of the AC voltage can be changed, for example, the measurement using the other resistance measuring device 1 of the same type is adjacent By making the frequencies of the AC voltages output from the AC power supplies 26 in the resistance measuring devices 1 different from each other in a measurement environment in which measurement is performed simultaneously at a location, interference between AC voltages output from the AC power supplies 26 is caused. It is possible to reliably prevent a situation in which the adjustment of the capacitance of the variable capacitor 24 and the determination of the contact state become inaccurate.

  Further, according to the contact determination device and the resistance measurement device 1, a notification unit that notifies that the voltage difference Vs output from the differential amplifier 27 does not become 0 V within the adjustment range of the capacitance of the variable capacitor 24 Due to the provision, for example, when it is intended to perform measurement using the shielded wire 60 in which the capacitance C1 is too large (too long), the user can be reliably notified of that. Therefore, according to the contact determination device and the resistance measurement device 1, the contact state between the contact terminals 63 and 71 and the to-be-contacted portion 51 is performed by performing measurement using the shield wire 60 whose capacitance C1 is too large (too long). It is possible to reliably prevent such a situation that the determination of V can not be accurately made or the insulation resistance Ri can not be accurately measured due to the influence of the capacitance C1 of the shield wire 60.

  In addition, the structure of a contact determination apparatus and a measuring apparatus is not limited to an above-described structure. For example, in the determination of the contact state, although the configuration example has been described above in which only the AC voltage is output without outputting the DC voltage, both the DC voltage and the AC voltage are output to superimpose the AC voltage on the DC voltage. A configuration in which the contact state is determined using the superimposed voltage may be employed. Also, a configuration may be employed in which the insulation resistance Ri is measured using this superimposed voltage.

  In addition, although the above describes the configuration example in which the determination of the contact state and the measurement of the insulation resistance Ri are switched by the operation of the operation unit 3, the processing unit 5 executes the determination of whether the contact state is good or not It is also possible to adopt a configuration in which the processing unit 5 automatically executes the measurement of the insulation resistance Ri when it is determined that the state is good. In this case, the instruction to start the determination of whether or not the contact state is good may be an instruction by operating the operation unit 3 or an instruction from a signal from an external device.

  In addition, although the above describes the example of measuring the insulation resistance Ri as the measurement amount, the measurement amount is not limited to the insulation resistance Ri. For example, a configuration may be employed in which the current value detected by the ammeter 22 is measured as the amount to be measured of the measurement target 50.

  Further, although the example in which the inductors 23a and 23b are respectively used as the first conversion element and the second conversion element has been described above, a configuration using resistances as the first conversion element and the second conversion element can also be adopted. Also, the resistors 25a, 25b, 25c can be omitted as appropriate according to the contents of the other components constituting the first circuit Pc1, the second circuit Pc2, and the third circuit Pc3.

DESCRIPTION OF SYMBOLS 1 resistance measurement apparatus 4 display part 5 process part 21 DC power supply 21a negative electrode 21b positive electrode 22 current meter 23a inductor 24b inductor 24 variable capacitor 26 AC power supply 27 differential amplifier 50 measurement object 51 to-be-contacted part 60 shield wire 61 core 61a tip 61b Base end 62 Shield 63 Contact terminal 70 Conductor 70a Tip 71 Contact terminal A1, A2 Position Pc1 1st circuit Pc 2 2nd circuit Pc 3 3rd circuit Ri insulation resistance V1, V2 voltage Vs voltage difference

Claims (4)

A core wire and a shield wire having a shield surrounding the core wire The first contact terminal connected to the tip of the core wire is brought into contact with one of the contact parts on the object to be measured, and the second contact wire is connected to the tip of the lead wire The measured amount of the measuring object in a state in which the contact terminal is brought into contact with the other to-be-contacted part in the measuring object and the direct current signal from the direct current signal source is supplied to the measuring object via the core wire and the conducting wire. A contact determination device capable of determining a contact state between each contact terminal and each contact portion in a measurement device that measures
A first circuit connecting the proximal end of the core wire to one electrode of the DC signal source, a second circuit connecting the proximal end of the shield to the one electrode, and the proximal end of the shield And a third circuit connected in parallel to the second circuit by connecting to the one electrode, and a detection circuit that detects a physical quantity capable of determining the contact state,
The first circuit includes a first conversion element for current-voltage conversion,
The second circuit includes a variable capacitance element connected in series and a second conversion element for current-voltage conversion,
The third circuit includes an AC signal source that outputs an AC signal for determining the contact state,
The detection circuit detects, as the physical quantity, a voltage difference between a voltage obtained by current-voltage conversion by the first conversion element and a voltage obtained by current-voltage conversion by the second conversion element.   The contact determination apparatus according to claim 1, wherein the alternating current signal source is configured to be capable of changing the frequency of the alternating current signal.   The contact determination apparatus according to claim 1, further comprising a notification unit that notifies that the voltage difference output from the detection circuit does not become 0 V within the adjustment range of the capacitance of the variable capacitance element.   The contact determination apparatus according to any one of claims 1 to 3, the direct current signal source, and an ammeter provided in the first circuit, the measurement based on the current value detected by the ammeter. A measuring device for measuring the measured amount of a subject.

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