JP2011085462A - Four-terminal resistance measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reliably determine a connection state of a pair of current supply terminals and a pair of voltage detection terminals to a resistor to be measured with a simple structure. <P>SOLUTION: A four-terminal resistance measuring device includes: a constant current source 3 for supplying a measurement current Im to the resistor 2 to be measured via the current supply terminals 5, 6; a measurement unit ME for measuring a both-terminal voltage V1 of the resistor 2 to be measured via the voltage detection terminals 7, 8; a disconnection detection unit DE1 for detecting a connection state of the terminals 5, 7 to the resistor 2 to be measured on the basis of a voltage V2 generated between the terminals 5, 7 by supplying a Hi-side AC current Ie1 to a path B including both terminals 5, 7; a disconnection detection unit DE2 for detecting the connection state of the terminals 6, 8 to the resistor 2 to be measured on the basis of a voltage V3 generated between the terminals 6, 8 by supplying a Lo-side AC current Ie2 to a path C including both terminals 6, 8; and a diode circuit 4 comprising two diodes 4a, 4b connected in parallel with reverse polarity and arranged between the constant current source 3 and the current supply terminal 5. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a four-terminal resistance measuring device having a pair of current supply terminals and a voltage detection terminal connected to a resistor to be measured.

  As this type of four-terminal resistance measuring device, the applicant has already proposed a four-terminal resistance measuring device disclosed in Patent Document 1 below. The outline of the four-terminal resistance measuring device will be described. As shown in FIG. 4, the four-terminal resistance measuring device 51 includes a high potential side (hereinafter also referred to as “Hi side”) and a low potential side (hereinafter referred to as “Lo”). A constant current source 3 for supplying a direct current measurement current Im to the resistor 2 to be measured and current detection terminals 7 and 8 on the Hi side and Lo side. A measurement unit (comprising a voltage detection unit 9, an A / D conversion unit 10 and a processing unit 15) that measures the voltage V1 of the resistor 2 to be measured, and each current supply terminal 5 for the resistor 2 to be measured 5. First disconnection detecting means (voltage detector 52) for detecting the connection state of 6 and second disconnection detecting means (Hi-side AC power supply 11 and the like) for detecting the connection state of the Hi-side voltage detection terminal 7 with respect to the resistor 2 to be measured. Hi side voltage detector 13) and Lo side with respect to the resistor 2 to be measured Third disconnection detecting means (Lo-side AC power supply 12 and Lo-side voltage detecting unit 14) for detecting the connection state of the pressure detection terminal 8 and each terminal 5 based on output signals from the respective disconnection detecting means 52, 13, 14 6, 6, 7, and 8, determination means (processing unit 15) that determines the connection state with respect to the resistor 2 to be measured.

  The first disconnection detecting means has a first comparator (not shown) that compares the output voltage (voltage amplitude) of the constant current source 3 with the first reference voltage, and the second disconnection detecting means is a Hi-side current supply. A Hi-side AC power supply 11 that supplies a first AC current (Hi-side AC current Ie1) to a Hi-side current path (path B) including the terminal 5 and the Hi-side voltage detection terminal 7; A second comparator (Hi-side voltage detector 13) that compares the voltage V2 generated in the current path with a predetermined second reference voltage, and the third disconnection detecting means includes the Lo-side current supply terminal 6 and the Lo-side voltage. A Lo-side AC power supply 12 that supplies a second AC current (Lo-side AC current Ie2) to the Lo-side current path (path C) including the detection terminal 8 and a voltage generated in the Lo-side current path by the Lo-side AC power supply 12 A third for comparing V3 with a predetermined third reference voltage It is constituted by a comparator (Lo-side voltage detector 14).

  In this four-terminal resistance measuring device, the output voltage (voltage amplitude) of the constant current source 3 is monitored by the voltage detection unit 52, and the path B including the Hi-side current supply terminal 5 and the Hi-side voltage detection terminal 7 is used. The Hi-side AC power source 11 allows the Hi-side AC current Ie1 to flow, and a voltage (generated voltage of the Hi-side AC power source 11) V2 generated between the Hi-side current supply terminal 5 and the Hi-side voltage detection terminal 7 is a Hi-side voltage detection unit. 13, and the Lo-side AC power source 12 is supplied with the Lo-side AC current Ie2 from the Lo-side AC power source 12 to the path C including the Lo-side current supply terminal 6 and the Lo-side voltage detection terminal 8, and the Lo-side current supply terminal 6 and Lo The voltage generated between the side voltage detection terminals 8 (the voltage generated by the Lo side AC power supply 12) V3 is monitored by the Lo side voltage detection unit 14, so that measurement is in progress (measured current Im in the resistor 2 to be measured). Is supplied Even in a state that), it is possible to perform break detection of the terminals 5, 6, 7, 8.

Japanese Patent Laying-Open No. 2005-69786 (page 4-7, FIG. 1)

  By the way, as a result of further examination of the above four-terminal resistance measuring device, the inventor of the present application has found that the second disconnection detecting means is on the Hi side in the path B including the Hi side current supply terminal 5 and the Hi side voltage detection terminal 7. The Hi-side AC power supply 11 that supplies the AC current Ie1 is provided, and the third disconnection detecting means supplies the Lo-side AC current Ie2 to the path C including the Lo-side current supply terminal 6 and the Lo-side voltage detection terminal 8. Since the Lo side AC power supply 12 to be supplied is provided, the second side disconnection detecting unit can be configured easily without using the first disconnection detecting unit (voltage detection unit 52), and the Hi side voltage detection terminal 7 and the Hi side can be easily configured. The connection state of the current supply terminal 5 was monitored, and it was considered that the connection state of the Lo side current supply terminal 6 together with the Lo side voltage detection terminal 8 could be monitored by the third disconnection detection means.

  However, as shown in FIG. 5, when the Hi-side current supply terminal 5 is disconnected (when not connected to the measured resistor 2 or when the contact resistance is high although connected), the measurement current Im As a result, the constant current source 3 functions as a constant voltage source, and as a result, the output impedance is lowered. For this reason, the Hi-side AC current Ie1 supplied from the Hi-side AC power supply 11 passes through the path D shown in the figure (from the output terminal 24 of the constant current source 3 to the Hi-side AC power supply 11, the Hi-side voltage detection terminal 7, and the device under measurement. The current flows to the output terminal 25 of the constant current source 3 via the resistor 2 and the Lo-side current supply terminal 6), so that the Hi-side AC is supplied even though the Hi-side current supply terminal 5 is disconnected. As a result that the output voltage (voltage V2) of the power source 11 does not increase, a problem that the disconnection of the Hi-side current supply terminal 5 cannot be detected even by comparing the voltage V2 in the Hi-side voltage detection unit 13 with the second reference voltage occurs. .

  As shown in FIG. 6, the problem is that the Lo-side current supply terminal 6 is disconnected from the resistor 2 to be measured (when the resistor 2 to be measured is not connected to the resistor to be measured 2 or is connected but has high contact resistance) In the case). Specifically, when the Lo-side current supply terminal 6 is in a disconnected state, the output impedance is lowered by the constant current source 3 functioning as a constant voltage source as described above. For this reason, the Lo-side AC current Ie2 supplied from the Lo-side AC power supply 12 passes through the path E (from the output terminal 24 of the constant current source 3 to the Hi-side current supply terminal 5, the resistor under test 2, the Lo side The current flows to the output terminal 25 of the constant current source 3 via the voltage detection terminal 8 and the Lo side AC power source 12, and thus the Lo side AC is supplied even though the Lo side current supply terminal 6 is disconnected. As a result of the output voltage (voltage V3) of the power supply 12 not increasing, a problem that the disconnection of the Lo-side current supply terminal 6 cannot be detected even by comparing the voltage V3 and the third reference voltage in the Lo-side voltage detection unit 14 occurs. .

  The present invention has been made in view of such a problem. The present invention has a simple configuration, and is capable of covering the high potential side current supply terminal, the low potential side current supply terminal, the high potential side voltage detection terminal, and the low potential side voltage detection terminal. The main object is to provide a four-terminal resistance measuring device that can reliably determine the connection state to the measuring resistor.

  In order to achieve the above object, a four-terminal resistance measuring device according to claim 1 is a current source for supplying a DC measuring current to a resistor under measurement via a high potential side current supply terminal and a low potential side current supply terminal; A measuring section for measuring a voltage across the resistor under measurement via a high potential side voltage detection terminal and a low potential side voltage detection terminal; a high portion including the high potential side current supply terminal and the high potential side voltage detection terminal; A high potential for detecting a connection state of the two terminals to the resistor to be measured based on a first inter-terminal voltage generated between the two terminals while supplying a high-potential side alternating current for detecting disconnection to the potential-side current path. A low potential side alternating current for detecting a disconnection is supplied to a low potential side current path including a side disconnection detection unit, the low potential side current supply terminal, and the low potential side voltage detection terminal, and a first generated between the two terminals. Based on voltage between two terminals A low-potential-side disconnection detection unit that detects a connection state of both terminals to the measured resistor, and based on detection results of the high-potential-side disconnection detection unit and the low-potential-side disconnection detection unit The connection state of the high potential side current supply terminal and the high potential side voltage detection terminal to the resistor and the connection state of the low potential side current supply terminal and the low potential side voltage detection terminal to the measured resistor are determined. A four-terminal resistance measuring device for calculating a resistance value of the resistor under measurement based on the measurement current and the voltage between both ends measured by the measuring unit, and two devices connected in parallel with opposite polarities. It is composed of a diode and is disposed between at least one of the current source and the high potential side current supply terminal and between the current source and the low potential side current supply terminal. The high-potential-side disconnection detection unit includes a high-potential-side AC power source that outputs the high-potential-side AC current and whose output AC voltage has a maximum amplitude that is less than the turn-on voltage of the diode; The low-potential-side disconnection detection unit includes a low-potential-side AC power source that outputs the low-potential-side AC current and whose output AC voltage has a maximum amplitude that is less than the turn-on voltage of the diode.

  The four-terminal resistance measuring device according to claim 2 is the four-terminal resistance measuring device according to claim 1, wherein the high-potential-side disconnection detecting unit detects the voltage between the first terminals and between the first terminals. A high-potential-side voltage detector that detects a connection state of the high-potential-side current supply terminal and the high-potential-side voltage detection terminal with respect to the resistor to be measured by comparing a voltage with a predetermined reference voltage; The low-potential-side disconnection detection unit detects the voltage between the second terminals and compares the voltage between the second terminals with a predetermined reference voltage, and the low-potential-side current supply terminal for the resistor to be measured; A low potential side voltage detection unit for detecting a connection state of the low potential side voltage detection terminal is provided.

  In the four-terminal resistance measuring apparatus according to claim 1, only the high potential side current supply terminal among the high potential side current supply terminal, the low potential side current supply terminal, the high potential side voltage detection terminal, and the low potential side voltage detection terminal is provided. In the case of disconnection, the output of the high potential side alternating current is blocked by the diode circuit, and in the case where only the low potential side current supply terminal is disconnected, the output of the low potential side alternating current is blocked by the diode circuit. . Also, when the high potential side voltage detection terminal is disconnected, the high potential side AC current is not output from the high potential side AC power supply, and when the low potential side voltage detection terminal is disconnected, the low potential side AC current is not output. Low potential side AC current is not output from the power supply. Thereby, when at least one of the high potential side current supply terminal and the high potential side voltage detection terminal is disconnected, the voltage between the first terminals rises, and the low potential side current supply terminal and the low potential side voltage detection terminal When at least one of them is disconnected, the voltage between the second terminals rises.

  Therefore, according to this four-terminal resistance measuring device, the high-potential side disconnection detecting unit has a simple configuration in which a diode circuit using two diodes is disposed, and the high-potential side disconnection detecting unit is based on the voltage between the first terminals. The connection state of the current supply terminal and the high potential side voltage detection terminal can be reliably detected, and the low potential side current supply terminal and the low potential side voltage detection are performed based on the voltage between the second terminals in the low potential side disconnection detection unit. It is possible to reliably detect the terminal connection state. That is, it is possible to reliably detect the connection state of the high potential side current supply terminal, the low potential side current supply terminal, the high potential side voltage detection terminal, and the low potential side voltage detection terminal to the measured resistor. it can.

  According to the four-terminal resistance measuring apparatus of claim 2, the first terminal voltage is detected, and the first terminal voltage is compared with a predetermined reference voltage to increase the high potential with respect to the resistor to be measured. A high-potential-side voltage detection unit configured to detect a connection state between the side-current supply terminal and the high-potential-side voltage detection terminal constitutes a high-potential-side disconnection detection unit, and detects the voltage between the second terminals and the second terminal. Low-potential side voltage detector having a low-potential-side voltage detector that detects the connection state of the low-potential-side current supply terminal and the low-potential-side voltage detection terminal to the resistance to be measured by comparing the voltage between the voltage and a predetermined reference voltage By configuring the disconnection detection unit, the first inter-terminal voltage and the reference voltage are compared, and the second inter-terminal voltage and the reference voltage are compared. High potential side current for resistor The connection state of the supply terminal and the high potential side voltage detection terminal can be detected, and the connection state of the low potential side current supply terminal and the low potential side voltage detection terminal to the measured resistor is determined based on the voltage between the second terminals. It can be detected reliably.

1 is a configuration diagram showing a configuration of a four-terminal resistance measuring device 1. FIG. In FIG. 1, it is also an explanatory view for explaining an operation when the Hi-side current supply terminal 5 is disconnected. In FIG. 1, it is also an explanatory diagram for explaining an operation when the Lo-side current supply terminal 6 is disconnected. It is a block diagram which shows the structure of the conventional four terminal resistance measuring apparatus 51. FIG. In FIG. 4, it is also an explanatory diagram for explaining the operation when the Hi-side current supply terminal 5 is disconnected. In FIG. 4, it is also an explanatory diagram for explaining the operation when the Lo-side current supply terminal 6 is disconnected.

  Hereinafter, an embodiment of a four-terminal resistance measuring device will be described with reference to the accompanying drawings.

  First, the configuration of the four-terminal resistance measuring device 1 will be described with reference to the drawings.

  A four-terminal resistance measuring apparatus 1 shown in FIG. 1 measures the resistance value of a resistor 2 to be measured, and includes a constant current source 3, a diode circuit 4, a pair of current supply terminals (Hi-side current supply terminal 5 and Lo side current supply terminal 6), a pair of voltage detection terminals (Hi side voltage detection terminal 7 and Lo side voltage detection terminal 8), voltage detection unit 9, A / D conversion unit 10, Hi side AC power supply 11, Lo side AC A power supply 12, a Hi side voltage detection unit 13, a Lo side voltage detection unit 14, a processing unit 15, and an output unit 16 are provided.

  The constant current source 3 is an example of a current source, and equivalently, as shown in FIG. 1, the constant current source 3 includes a current buffer 21 composed of an operational amplifier, a constant voltage source (DC constant voltage source) 22, and a resistor 23. ing. In this case, the constant voltage source 22 is connected between the non-inverting input terminal of the current buffer 21 and the ground, and the resistor 23 is connected between the inverting input terminal of the current buffer 21 and the ground. One output terminal 24 of the pair of output terminals 24 and 25 is connected to the output terminal of the current buffer 21, and the other output terminal 25 is connected to the inverting input terminal of the current buffer 21. In the constant current source 3, the non-inverting input terminal and the inverting input terminal of the current buffer 21 formed of an operational amplifier are in a virtual short-circuit state. Therefore, a DC constant voltage is constantly applied to the resistor 23 from the constant voltage source 22. It has become a state.

  With this configuration, the constant current source 3 divides the voltage value of the DC constant voltage output from the constant voltage source 22 by the resistance value of the resistor 23 with respect to the external circuit connected between the pair of output terminals 24 and 25. Measurement current (DC constant current) Im having a current value (known current value) obtained in this manner can be supplied. Note that the voltage value of the voltage output from the output terminal 24 of the constant current source 3 varies depending on the resistance value of the resistor under test 2, but between the terminals 5, 6, 7, 8 and the resistor under test 2. The forward voltage of the diodes 4a and 4b constituting the diode circuit 4 is also taken into consideration so that the measured current Im having a desired current value can be supplied to the measured resistor 2 even if the contact resistance varies to some extent. Therefore, the voltage value always exceeds the turn-on voltage Von of the diodes 4a and 4b.

  As shown in FIG. 1, the diode circuit 4 is composed of two diodes 4a and 4b connected in parallel with opposite polarities. In this case, the diodes 4a and 4b are preferably the same type of diodes having the same electrical characteristics (for example, turn-on voltage Von, forward voltage, forward current, etc.). As an example, the diode circuit 4 thus configured has one end (in this example, the anode terminal of the diode 4a) connected to one output terminal 24 of the constant current source 3, and the other end is connected to the Hi side as will be described later. Connected to the current supply terminal 5 and disposed between the output terminal 24 of the constant current source 3 and the Hi-side current supply terminal 5.

  The Hi-side current supply terminal 5 is connected to the other end of the diode circuit 4 (in this example, the cathode terminal of the diode 4a). The Lo-side current supply terminal 6 is connected to the other output terminal 25 of the constant current source 3. The Hi side voltage detection terminal 7 is connected to one input terminal of the voltage detection unit 9, and the Lo side voltage detection terminal 8 is connected to the other input terminal of the voltage detection unit 9.

  The voltage detection unit 9 detects a voltage V1 generated between the Hi side voltage detection terminal 7 and the Lo side voltage detection terminal 8 connected to a pair of input terminals having a high input impedance, and a voltage indicating a waveform of the voltage V1. The signal Sv is output. The A / D conversion unit 10 receives the voltage signal Sv and generates and outputs voltage data Dv indicating the voltage (amplitude) of the voltage signal Sv by sampling at a predetermined sampling period. The voltage detection unit 9 and the A / D conversion unit 10 together with the processing unit 15 constitute a measurement unit ME.

  The Hi-side AC power supply 11 is connected to the Hi-side current supply terminal 5 and the Hi-side voltage detection terminal 7 and supplies a Hi-side AC current (AC constant current) Ie1 for contact check between these terminals 5 and 7 ( Output). The Hi-side AC power supply 11 constitutes a Hi-side disconnection detection unit DE1 together with the Hi-side voltage detection unit 13. With this configuration, the Hi-side disconnection detection unit DE1 supplies the Hi-side AC current Ie1 for disconnection detection to the Hi-side current path (path B) including the Hi-side current supply terminal 5 and the Hi-side voltage detection terminal 7. Based on the voltage (first inter-terminal voltage) V2 generated between both terminals 5 and 7, the connection state of both terminals 5 and 7 to the resistor 2 to be measured is detected. In this case, the Hi-side AC power supply 11 is defined in advance such that the maximum output amplitude (voltage) Vmax1 is less than the turn-on voltage Von of the diodes 4a and 4b. That is, the maximum output amplitude Vmax1 is defined as a voltage value at which the diodes 4a and 4b are not turned on by the supply of the Hi-side alternating current Ie1. The turn-on voltage Von of the diode varies depending on the type, and is about 0.2 [V] for the germanium diode and about 0.7 [V] for the silicon diode.

  The Lo-side AC power supply 12 is connected to the Lo-side current supply terminal 6 and the Lo-side voltage detection terminal 8, and supplies a Lo-side AC current (AC constant current) Ie2 for contact check between these terminals 6 and 8 ( Output). The Lo side AC power supply 12 constitutes the Lo side disconnection detection unit DE2 together with the Lo side voltage detection unit 14. With this configuration, the Lo-side disconnection detection unit DE2 supplies the Lo-side AC current Ie2 for disconnection detection to the Lo-side current path (path C) including the Lo-side current supply terminal 6 and the Lo-side voltage detection terminal 8. Based on the voltage (second inter-terminal voltage) V3 generated between both terminals 6 and 8, the connection state of both terminals 6 and 8 to the resistor 2 to be measured is detected. In this case, the Lo side AC power supply 12 is defined in advance such that the maximum output amplitude (voltage) Vmax2 is less than the turn-on voltage Von of the diodes 4a and 4b. That is, the maximum output amplitude Vmax2 is defined as a voltage value at which the diodes 4a and 4b are not turned on by the supply of the Lo-side alternating current Ie2.

  The Hi-side voltage detection unit 13 includes a comparator (not shown), and the input impedance of each input terminal to which the Hi-side current supply terminal 5 and the Hi-side voltage detection terminal 7 are connected is defined as a high impedance. Yes. The Hi-side voltage detector 13 detects the voltage V2 generated between the Hi-side current supply terminal 5 and the Hi-side voltage detection terminal 7 and compares it with a reference voltage Vref defined in advance. The connection state of both terminals 5 and 7 to the body 2 is detected. Specifically, when the voltage V2 exceeds the reference voltage Vref as a result of this comparison, the Hi-side voltage detection unit 13 determines that at least one of the Hi-side current supply terminal 5 and the Hi-side voltage detection terminal 7 is a resistance to be measured. A detection signal S1 indicating a connection state that is not normally connected to the body 2 (specifically, one terminal of the resistor 2 to be measured) is generated and output.

  In this case, the total resistance value of the contact resistance between the Hi-side current supply terminal 5 and one terminal of the measured resistor 2 and the contact resistance between the Hi-side voltage detection terminal 7 and one terminal of the measured resistor 2 is increased. As a result, the voltage V2 also increases. In this example, the voltage V2 when the total resistance value reaches a predetermined allowable maximum value is defined as the reference voltage Vref. Therefore, when the total resistance value of each of the contact resistances exceeds the allowable maximum value, the Hi-side voltage detection unit 13 (at least one of the Hi-side current supply terminal 5 and the Hi-side voltage detection terminal 7 is the measured resistor 2 The detection signal S1 is generated and output when the terminal is separated from one of the terminals (including the case of non-contact).

  Similarly to the Hi-side voltage detection unit 13, the Lo-side voltage detection unit 14 includes a comparator (not shown), and each input to which the Lo-side current supply terminal 6 and the Lo-side voltage detection terminal 8 are connected. The input impedance of the terminal is specified as high impedance. The Lo-side voltage detector 14 detects a voltage V3 generated between the Lo-side current supply terminal 6 and the Lo-side voltage detection terminal 8, and compares it with a reference voltage Vref defined in advance, thereby measuring the resistance to be measured. The connection state of both terminals 6 and 8 to the body 2 is detected. Specifically, as a result of this comparison, when the voltage V3 exceeds the reference voltage Vref, the Lo-side voltage detector 14 determines that at least one of the terminals 6 and 8 is the resistor 2 to be measured (specifically, , And generates and outputs a detection signal S2 indicating a connection state that is not normally connected to the other terminal of the resistor 2 to be measured.

  In this case, the reference voltage Vref of the Lo side voltage detection unit 14 is also defined in the same manner as in the case of the Hi side voltage detection unit 13. Therefore, the Lo-side voltage detection unit 14 has a contact resistance between the Lo-side current supply terminal 6 and the other terminal of the measured resistor 2 and a contact between the Lo-side voltage detection terminal 8 and the other terminal of the measured resistor 2. When the total resistance value of the resistors exceeds the allowable maximum value (when at least one of the Lo-side current supply terminal 6 and the Lo-side voltage detection terminal 8 is separated from the other terminal of the resistor 2 to be measured (when not in contact)) In addition, the detection signal S2 is generated and output.

  The processing unit 15 includes a CPU and an internal memory, and includes a Hi-side current supply terminal 5, a Hi-side voltage detection terminal 7, a Lo-side current supply terminal 6, and a Lo-side voltage detection terminal 8 for the resistor 2 to be measured. A contact check process (connection determination process) and a resistance value measurement process for the resistor 2 to be measured are executed. For example, the output unit 16 includes a display device such as an LCD (Liquid Crystal Display) and displays the result of the contact check process and the result of the resistance value measurement process.

  Next, the operation of the four-terminal resistance measuring device 1 will be described. It should be noted that the connection of the Hi-side current supply terminal 5 and the Hi-side voltage detection terminal 7 to one of the terminals to be measured 2 and the Lo-side current supply terminal 6 and the Lo-side voltage detection terminal 8 in the to-be-measured resistor Assume that the connection to the other terminal has been completed in advance.

  In the operating state of the four-terminal resistance measuring device 1, as a result of the above connection operations being performed satisfactorily, the Hi-side current supply terminal 5 and the Hi-side voltage detection terminal 7 are connected to the resistor 2 to be measured, as shown in FIG. When the Lo side current supply terminal 6 and the Lo side voltage detection terminal 8 are normally connected to the other terminal of the resistor 2 to be measured, the output terminal of the constant current source 3 Since the voltage value of the voltage (DC voltage) output from 24 exceeds the turn-on voltage Von of the diode 4a, the constant current source 3 is connected to the path shown in the figure (that is, the output terminal 24, diode circuit 4, Hi side). The operation of supplying the measurement current Im to the path A) via the current supply terminal 5, the resistor under test 2 and the Lo-side current supply terminal 6 to the output terminal 25 is started.

  In addition, the Hi-side AC power supply 11 operates to supply the Hi-side AC current Ie1 to the path B that reaches the Hi-side voltage detection terminal 7 via one terminal of the Hi-side current supply terminal 5 and the resistor 2 to be measured. Has started. Similarly, the Lo-side AC power supply 12 also supplies the Lo-side AC current Ie2 to the path C that reaches the Lo-side voltage detection terminal 8 via the Lo-side current supply terminal 6 and the other terminal of the resistor 2 to be measured. The operation has started.

  Further, the Hi-side voltage detection unit 13 starts comparing the input voltage V2 (voltage between the Hi-side current supply terminal 5 and the Hi-side voltage detection terminal 7) with the reference voltage Vref, and the Lo-side voltage detection unit 14 Starts comparison of the input voltage V3 (the voltage between the Lo-side current supply terminal 6 and the Lo-side voltage detection terminal 8) and the reference voltage Vref.

  The voltage detector 9 detects the voltage V1 generated between the Hi-side voltage detection terminal 7 and the Lo-side voltage detection terminal 8, and starts an operation of outputting a voltage signal Sv indicating the waveform of the voltage V1. The A / D converter 10 receives the voltage signal Sv and samples and outputs the voltage data Dv indicating the voltage (amplitude) of the voltage signal Sv by sampling at a predetermined sampling period. Has started.

  In this way, in a state where each component of the four-terminal resistance measurement device 1 has started its operation, the processing unit 15 first performs a contact check process. In this contact check process, the processing unit 15 detects the presence or absence of the output of the detection signal S1 from the Hi-side voltage detection unit 13, thereby detecting the Hi-side current supply terminal 5 and Hi for one terminal of the resistor 2 to be measured. The connection state of the side voltage detection terminal 7 is determined. Further, the processing unit 15 detects the presence or absence of the output of the detection signal S2 from the Lo side voltage detection unit 14 to thereby detect the Lo side current supply terminal 6 and the Lo side voltage detection terminal for the other terminal of the resistor 2 to be measured. 8 is determined.

  In the state shown in FIG. 1, the Hi-side current supply terminal 5, the Hi-side voltage detection terminal 7, the Lo-side current supply terminal 6 and the Lo-side voltage detection terminal 8 are electrically connected to corresponding terminals of the resistor 2 to be measured. When the contact resistance with the terminal of the resistor 2 to be measured is small, the voltages V2 and V3 are both equal to or lower than the reference voltage Vref, and therefore are detected from the Hi-side voltage detector 13 and the Lo-side voltage detector 14. Signals S1 and S2 are not output. Therefore, the processing unit 15 determines that all four terminals of the Hi-side current supply terminal 5 to the Lo-side voltage detection terminal 8 are normally connected, and displays that fact on the output unit 16. This completes the contact check process. Thus, in the contact check process, when it is determined that all four terminals of the Hi side current supply terminal 5 to the Lo side voltage detection terminal 8 are normally connected, the processing unit 15 then measures the resistance value. Transition to processing.

  In this resistance value measurement process, the processing unit 15 calculates the voltage value of the voltage V1, which is the voltage across the resistor 2 to be measured, based on the voltage data Dv output from the A / D conversion unit 10. Based on the calculated voltage value of the voltage V1 and the current value (known) of the measured current Im output from the constant current source 3, the resistance value of the resistor 2 to be measured is measured and displayed on the output unit 16. Thereby, the resistance value measurement process is completed.

  On the other hand, although the Hi-side current supply terminal 5, the Hi-side voltage detection terminal 7, the Lo-side current supply terminal 6 and the Lo-side voltage detection terminal 8 are electrically connected to corresponding terminals of the resistor 2 to be measured, Due to the large contact resistance between the terminals of the resistor 2 to be measured, the total resistance value of the contact resistances on the Hi-side current supply terminal 5 and the Hi-side voltage detection terminal 7 side exceeds the allowable maximum value. The Hi-side voltage detection unit 13 generates and outputs a detection signal S1 when it is present. Further, when the total resistance value of the contact resistances on the Lo-side current supply terminal 6 and the Lo-side voltage detection terminal 8 side exceeds the allowable maximum value, the Lo-side voltage detection unit 14 generates and outputs a detection signal S2. .

  When the Hi-side voltage detection terminal 7 is not connected to the resistor 2 to be measured, the Hi-side voltage detection terminal 7 side terminal of the Hi-side AC power supply 11 has a high-impedance Hi-side voltage detection unit 13 and a voltage detection unit. Only 9 input terminals are connected. For this reason, the path | route B through which the Hi side alternating current Ie1 flows is not formed. When the Hi-side current supply terminal 5 is not connected to the resistor 2 to be measured, the path B is not formed in the same manner as when the Hi-side voltage detection terminal 7 is not connected, as shown in FIG. The diode circuit 4 is arranged between the output terminal 24 of the constant current source 3, the Hi side current supply terminal 5 and the Hi side AC power source 11, and the maximum output amplitude Vmax1 of the Hi side AC power source 11 is turned on. Unlike the conventional four-terminal resistance measuring device 51, the path D is not formed because it is defined to be less than the voltage Von. Moreover, since the impedance of the Hi-side AC power supply 11 is high, the measurement current Im from the constant current source 3 does not flow. That is, the path D by the measurement current Im is not formed.

  For this reason, as a result of the Hi-side AC power source 11 not outputting the Hi-side AC current Ie1, the voltage (voltage amplitude) output from the Hi-side AC power source 11 to supply the Hi-side AC current Ie1 reaches the maximum output amplitude Vmax1. That is, the voltage V2 reaches Vmax1. As a result, the Hi-side voltage detector 13 compares the voltage V2 with the reference voltage Vref, and generates and outputs a detection signal S1.

  Even when the Lo-side current supply terminal 6 or the Lo-side voltage detection terminal 8 is not connected to the resistor 2 to be measured, as in the case of the Hi-side current supply terminal 5 or the Hi-side voltage detection terminal 7 described above, As shown in FIG. 3, the path C and path E for the flow of the Lo-side alternating current Ie2 are not formed. Further, since the impedance of the Lo side voltage detector 14 is high, the measurement current Im from the constant current source 3 does not flow. That is, the path E by the measurement current Im is not formed. For this reason, as a result of the Lo-side AC current Ie2 not being output from the Lo-side AC power source 12, the voltage (voltage amplitude) output from the Lo-side AC power source 12 to supply the Lo-side AC current Ie2 reaches the maximum output amplitude Vmax2. That is, the voltage V3 reaches Vmax2. Thereby, the Lo side voltage detection part 14 compares this voltage V3 with the reference voltage Vref, and produces | generates and outputs detection signal S2.

  As described above, when the detection signal S1 is output from the Hi-side voltage detection unit 13, the processing unit 15 inputs the detection signal S1 in the contact check process, and thus the Hi-side current supply terminal 5 and the Hi-side voltage detection terminal. 7, it is determined that a connection failure has occurred in at least one of them, and the fact is displayed on the output unit 16. Further, when the detection signal S2 is output from the Lo side voltage detection unit 14, the processing unit 15 inputs the detection signal S2 in the contact check process, and therefore, of the Lo side current supply terminal 6 and the Lo side voltage detection terminal 8. It is determined that a connection failure has occurred in at least one of them, and that effect is displayed on the output unit 16. In this case, after completing the display process for the output unit 16, the processing unit 15 completes the contact check process and stops the resistance value measurement process.

  As described above, in this four-terminal resistance measuring apparatus 1, the diode circuit 4 composed of the two diodes 4a and 4b connected in parallel with opposite polarities is connected to the output terminal 24 of the constant current source 3 and the Hi-side current supply terminal. 5 and at least one between the other output terminal 25 of the constant current source 3 and the Lo-side current supply terminal 6, and the output AC voltage of the Hi-side AC power supply 11 in the Hi-side disconnection detection unit DE1. Is defined to be less than the turn-on voltage Von of the diodes 4a and 4b, and the maximum amplitude of the output AC voltage of the Lo-side AC power supply 12 in the Lo-side disconnection detector DE2 is defined to be less than the turn-on voltage Von of the diodes 4a and 4b. ing.

  Therefore, when only the Hi-side current supply terminal 5 among the Hi-side current supply terminal 5, the Lo-side current supply terminal 6, the Hi-side voltage detection terminal 7 and the Lo-side voltage detection terminal 8 is disconnected (Hi-side current supply terminal). In the case where only 5 is not connected to the resistor 2 to be measured), the output of the Hi-side AC current Ie1 to the path D is blocked by the diode circuit 4, and only the Lo-side current supply terminal 6 is disconnected. Even in the case (when only the Lo-side current supply terminal 6 is not connected to the resistor 2 to be measured), the diode circuit 4 blocks the output of the Lo-side alternating current Ie2 to the path E. Moreover, since each input impedance of the voltage detection part 9, the Hi side voltage detection part 13, and the Lo side voltage detection part 14 is high, even when the Hi side voltage detection terminal 7 is disconnected, the Hi side AC power supply 11 is connected to the Hi side AC. Even when the current Ie1 is not output and the Lo-side voltage detection terminal 8 is disconnected, the Lo-side AC power source 12 does not output the Lo-side AC current Ie2. Thus, when at least one of the Hi-side current supply terminal 5 and the Hi-side voltage detection terminal 7 is disconnected, the voltage V2 rises, and at least one of the Lo-side current supply terminal 6 and the Lo-side voltage detection terminal 8 is When disconnection occurs, the voltage V3 increases.

  Therefore, according to the four-terminal resistance measuring apparatus 1, the Hi-side current supply terminal 5 and the Lo-side current supply terminal 6 have a simple configuration in which the diode circuit 4 using the two diodes 4a and 4b is provided. Of the Hi side voltage detection terminal 7 and the Lo side voltage detection terminal 8, not only when the Hi side voltage detection terminal 7 or the Lo side voltage detection terminal 8 is disconnected, but only the Hi side current supply terminal 5 or the Lo side Even when only the current supply terminal 6 is disconnected, based on the voltages V2 and V3, the occurrence of the disconnection is detected by the Hi-side disconnection detection unit DE1 (specifically, the Hi-side voltage detection unit 13) or the Lo-side disconnection detection unit DE2 ( Specifically, the Lo-side voltage detection unit 14) can reliably detect and output the detection signals S1 and S2 to the processing unit 15. As a result, the current supply terminals 5 and 6 and the voltage detection terminals 7 are output. Unconnected state to the measured resistor 2 for all terminals 8 can be reliably detected.

  Further, according to the four-terminal resistance measuring device 1, the voltage V2 is detected and the voltage V2 is compared with a predetermined reference voltage Vref to compare the Hi-side current supply terminal 5 and the Hi side with respect to the resistor 2 to be measured. The Hi-side disconnection detection unit DE1 is configured by including the Hi-side voltage detection unit 13 that detects the connection state of the voltage detection terminal 7, and also detects the voltage V3 and compares the voltage V3 with a predetermined reference voltage Vref. Since the Lo-side disconnection detection unit DE2 is configured by including the Lo-side voltage detection unit 14 that detects the connection state of the Lo-side current supply terminal 6 and the Lo-side voltage detection terminal 8 to the resistor 2 to be measured, the voltage V2 Are compared with the reference voltage Vref, and the voltage V3 and the reference voltage Vref are compared, but both terminals 5 and 7 for the resistor 2 to be measured are based on the voltage V2. It is possible to detect the connected state, it is possible to reliably detect the connection state of the terminals 6 and 8 with respect to the measuring resistor 2 based on the voltage V3.

  Note that the diode circuit 4 is disposed between the output terminal 24 of the constant current source 3 and the Hi-side current supply terminal 5 as described above. Since the diode circuit 4 may be disposed between the current supply terminal 5 and at least one of the output terminal 25 of the constant current source 3 and the Lo side current supply terminal 6, the diode circuit 4 is connected to the output of the constant current source 3. A configuration that is disposed only between the terminal 25 and the Lo-side current supply terminal 6, between the output terminal 24 of the constant current source 3 and the Hi-side current supply terminal 5, and between the output terminal 25 of the constant current source 3 and Lo It is also possible to employ a configuration in which the diode circuits 4 are respectively disposed between the side current supply terminals 6.

  In this case, when the diode circuits 4 are arranged in two places as in the latter configuration, two diode circuits 4 are arranged in series on the path A of the measurement current Im, so that the output of the constant current source 3 The voltage value of the voltage output from the terminal 24 is defined as a voltage value exceeding twice the turn-on voltage Von of the diodes 4a and 4b. Further, in this configuration, the output amplitudes of the Hi-side AC power supply 11 and the Lo-side AC power supply 12 can be doubled as compared with the case where there is only one diode circuit 4, so the Hi-side current supply terminal 5 and the Lo-side current supply terminal 6. The contact check for the Hi-side voltage detection terminal 7 and the Lo-side voltage detection terminal 8 can be performed with high accuracy using a higher voltage. In addition, although the diode 4a of the diode circuit 4 is configured by a single diode, a plurality of diodes may be connected in series. Similarly, the diode 4b can be configured by connecting a plurality of diodes in series.

  Further, the example in which the reference voltage Vref is shared by the Hi side voltage detection unit 13 and the Lo side voltage detection unit 14 has been described above, but it corresponds to variations in output voltages (amplitudes) of the Hi side AC power supply 11 and the Lo side AC power supply 12. Of course, each reference voltage Vref may be a different voltage. In addition, although the example in which the constant current source 3 is used as the current source for supplying the measurement current Im has been described above, the current value of the measurement current Im supplied to the resistor 2 to be measured is output to the processing unit 15 in real time. A current source having a function can be used as a current source for supplying the measurement current Im, even if it is not a constant current source.

DESCRIPTION OF SYMBOLS 1 Four-terminal resistance measuring apparatus 2 Resistor to be measured 3 Constant current source 4 Diode circuit 4a, 4b Diode 5 Hi side current supply terminal 6 Lo side current supply terminal 7 Hi side voltage detection terminal 8 Lo side voltage detection terminal 11 Hi side AC Power supply 12 Lo-side AC power supply 13 Hi-side voltage detection unit 14 Lo-side voltage detection unit 15 Processing unit DE1 Hi-side disconnection detection unit DE2 Lo-side disconnection detection unit Im Measurement current ME Measurement unit V1, V2 Voltage Vref Reference voltage

Claims (2)

A current source for supplying a DC measurement current to the measured resistor via the high potential side current supply terminal and the low potential side current supply terminal;
A measuring unit for measuring a voltage across the resistor under measurement via a high potential side voltage detection terminal and a low potential side voltage detection terminal;
Based on a first inter-terminal voltage generated between the two terminals while supplying a high-potential side alternating current for disconnection detection to a high-potential side current path including the high-potential side current supply terminal and the high-potential side voltage detection terminal. A high-potential-side disconnection detector that detects the connection state of the two terminals with respect to the measured resistor,
Based on a second inter-terminal voltage generated between the two terminals while supplying a low-potential side alternating current for disconnection detection to a low-potential side current path including the low-potential side current supply terminal and the low-potential side voltage detection terminal. A low-potential-side disconnection detector that detects the connection state of the two terminals with respect to the resistor to be measured.
Based on the detection results of the high potential side disconnection detection unit and the low potential side disconnection detection unit, the connection state of the high potential side current supply terminal and the high potential side voltage detection terminal to the resistor to be measured and the measurement target A connection state of the low potential side current supply terminal and the low potential side voltage detection terminal to the resistor is determined, and the resistance of the measured resistor is determined based on the measurement current and the voltage between both ends measured by the measurement unit. A four-terminal resistance measuring device for calculating a resistance value,
It is composed of two diodes connected in parallel with opposite polarities, and at least between the current source and the high potential side current supply terminal and between the current source and the low potential side current supply terminal. With a diode circuit arranged on one side,
The high-potential-side disconnection detection unit includes a high-potential-side AC power source that outputs the high-potential-side AC current and has a maximum amplitude of an output AC voltage that is less than a turn-on voltage of the diode.
The low-potential-side disconnection detection unit outputs a low-potential-side AC current, and includes a low-potential-side AC power supply in which the maximum amplitude of the output AC voltage is defined to be less than the turn-on voltage of the diode . The high-potential-side disconnection detection unit detects the voltage between the first terminals and compares the voltage between the first terminals and a predetermined reference voltage to the high-potential-side current supply terminal for the resistor to be measured. And a high-potential-side voltage detector that detects the connection state of the high-potential-side voltage detection terminal,
The low-potential-side disconnection detection unit detects the voltage between the second terminals and compares the voltage between the second terminals and a predetermined reference voltage to the low-potential-side current supply terminal for the resistor to be measured. The four-terminal resistance measuring device according to claim 1, further comprising a low-potential-side voltage detection unit that detects a connection state of the low-potential-side voltage detection terminal.

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