JP2011085483A - Impedance measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To ensure measurement accuracy by detecting contact state of a probe. <P>SOLUTION: The impedance measuring device includes a measuring current supply section 6 for supplying a measuring current Im via probes 3a, 3b; a voltage detecting section 7 detecting a voltage Vm1 of a measured object 2 via probes 4a, 4b; a first contact state detecting section 8 for detecting the contact state of an electrode 2a and the probes 3a, 4a; a second contact state detecting section 9 for detecting the contact state of an electrode 2b and the probes 3b, 4b; and a processing section 10 for carrying out measurement processing to measure an impedance Z, from the measured current Im and voltage Vm1. In performing the measurement processing, the processing section 10 repeats a determination processing of the contact state of the probes 3a, 3b, 4a, 4b, based on the detected results at the contact state detecting sections 8, 9, treats the impedance Z as a measured value, when the contact state has not been determined as being defective, until the measurement processing is completed, and reassumes a new measurement processing, when the contact state is determined as being defective. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an impedance measuring apparatus that measures the impedance of a measurement object by a four-terminal method.

  As this type of impedance measuring apparatus, an impedance measuring apparatus disclosed in Patent Document 1 below is known. This impedance measuring apparatus supplies a current to an impedance element through a pair of first measuring elements and a pair of second measuring elements that are in contact with electrodes of the impedance element as a measurement object, respectively, and the first measuring element. A power supply for measuring, a measuring means for measuring a voltage appearing in the impedance element through the second measuring element and calculating an impedance value by calculation with a current, and the first measuring element and the second measuring element in contact with the impedance element And a switching means having a switching contact for selectively switching the first measuring element and the second measuring element to the power source, the measuring means, and the detecting means. Further, in this impedance measuring apparatus, the first contact and the second contact are energized after switching from the detection means to the power source and the measurement means, and are switched to the detection means after the energization is stopped, The operation timing of the power supply and the measuring means is set.

  According to this impedance measuring apparatus, it is confirmed whether the probe contacts the electrode of the impedance element, and after the switching contact is switched for measurement, a current flows from the power source to the impedance element, and the impedance is measured by the measuring means. Therefore, when the probe contacts / releases for measurement, no current flows through the probe, so that no arc is generated in the probe and it is possible to prevent the probe from being worn. .

Japanese Patent No. 3017693 (page 2, Fig. 1)

  However, the above-described impedance measuring apparatus has the following problems to be solved. That is, in this type of impedance measuring apparatus, after the detection means detects completion of contact of the first measuring element and the second measuring element with the impedance element, the first measuring element and the second measuring element are , Switching from the detection means to the power supply and the measurement means, and then the power supply supplies current to the impedance element via the first probe, and the measurement means supplies the voltage appearing on the impedance element via the second probe. The impedance is calculated by calculating the current supplied to the impedance element and the measured voltage.

  For this reason, the impedance measuring apparatus has a result that the detection unit detects the completion of contact of the first measuring element and the second measuring element (probe) with the impedance element and the measurement of the impedance in series. When a contact failure occurs during impedance measurement, there is a problem to be solved that an accurate impedance cannot be measured. In addition, when determining the quality of the impedance element (measurement object) based on the measured impedance, it is impossible to measure an accurate impedance, and as a result, a non-defective impedance element is erroneously determined as a defective product. There is also a problem that the yield decreases.

  The present invention has been made to solve such a problem, and it is a main object of the present invention to provide an impedance measuring device that can detect the contact state of a probe to ensure measurement accuracy and improve yield during manufacturing. To do.

  In order to achieve the above object, the impedance measuring apparatus according to claim 1 supplies a measurement current to the measurement object via the first current supply probe and the second current supply probe that can contact both electrodes of the measurement object. A first voltage detection probe and a second voltage that can contact a measurement current supply unit and an interelectrode voltage generated between the two electrodes of the measurement object when the measurement current flows through the measurement object. A voltage detection unit for detecting via a detection probe; a first contact state detection unit for detecting a contact state of the first current supply probe and the first voltage detection probe with respect to one of the electrodes; A second contact state detection unit for detecting a contact state of the second current supply probe and the second voltage detection probe with respect to the other electrode of the two electrodes; and at least A processing unit that performs a measurement process for measuring the impedance of the measurement object based on the current value of the measurement current and the voltage value of the interelectrode voltage, and the processing unit is performing the measurement process, In the measurement process, when the contact state determination process of each probe based on the detection result by each contact state detection unit is repeatedly executed and the contact state is not determined to be defective by the completion of the measurement process, The measured impedance is used as a measurement value, and when the contact state is determined to be defective before the completion of the measurement process, the new measurement process is restarted and the determination process is repeatedly executed.

  The impedance measuring apparatus according to claim 2 is the impedance measuring apparatus according to claim 1, wherein the processing unit calculates a differential value for the voltage value of the interelectrode voltage detected by the voltage detecting unit per unit time. A comparison process that is compared with a reference value defined in advance while being calculated is repeatedly executed together with the determination process, and when the contact state is not determined to be defective by the completion of the measurement process, and in the comparison process, the differentiation When it is not determined that the value exceeds the reference value, the impedance measured in the measurement process is used as the measurement value, and when the contact state is determined to be defective by the completion of the measurement process, or the differentiation is performed in the comparison process. When it is determined that the value exceeds the reference value, a new measurement process is restarted and the determination process and the previous Repeating the comparison process to run.

  The impedance measuring device according to claim 3 is the impedance measuring device according to claim 1 or 2, wherein the processing unit is an upper limit number of times that the number of restarts of the measurement process for one measurement object is predetermined. Or when the total execution time of all the measurement processes for one measurement object reaches a predetermined upper limit time, the measurement process for the one measurement object is terminated.

  The impedance measuring device according to claim 4 is the impedance measuring device according to any one of claims 1 to 3, wherein the processing unit stores the number of times the measurement process is restarted for one measurement object. Remember me.

  In the impedance measuring apparatus according to claim 1, the processing unit repeatedly executes the determination process on the contact state of each probe during the execution of the measurement process, and determines that the contact state is defective in the determination process until the measurement process is completed. If not determined, the impedance measured in the measurement process is used as a measurement value. If the contact state is determined to be defective in the determination process before the completion of the measurement process, a new measurement process is restarted and the determination process is repeatedly executed.

  Therefore, according to this impedance measuring apparatus, measurement accuracy can be ensured by restarting the measurement process based on the detection result of the contact state of each probe by repeatedly executing the discrimination process during the execution of the measurement process. . In addition, when determining the quality of the measurement object based on the measured impedance, even when the contact state becomes defective, the measurement process is restarted to obtain an accurate impedance in a good contact state. Since measurement can be performed, it is possible to reliably avoid a situation where a non-defective measurement object is mistakenly determined as a defective product, and as a result, it is possible to improve yield during manufacturing.

  Further, in the impedance measuring apparatus according to claim 2, the comparison process for calculating the differential value for the voltage value of the interelectrode voltage detected by the voltage detection unit for each unit time and comparing it with the reference value is repeatedly executed together with the discrimination process. If the contact state is not determined to be defective before the measurement process is completed and if the differential value is not determined to exceed the reference value in the comparison process, the impedance measured in the measurement process is used as the measurement value. When it is determined that the contact state is defective before completion or when it is determined that the differential value exceeds the reference value in the comparison process, a new measurement process is resumed and the determination process and the comparison process are repeatedly performed. Therefore, according to this impedance measuring device, for example, impedance measurement using an inter-electrode voltage having an abnormal voltage value that is obtained when noise is superimposed is avoided, so that impedance measurement accuracy is further improved. be able to.

  According to the impedance measuring apparatus of claim 3, when the number of restarts of the measurement process for one measurement object reaches a predetermined upper limit number, or for all measurement processes for one measurement object. When the total execution time reaches a predetermined upper limit time, the processing unit ends the measurement process for this one measurement object, so that the measurement process is repeated indefinitely and the measurement time becomes long. The situation can be avoided.

  According to the impedance measuring apparatus of the fourth aspect, since the processing unit stores the number of restarts of the measurement process in the storage unit, when the number of times tends to increase based on the stored number of times, for example, each probe Can be determined as being deteriorated. Therefore, as a result of performing appropriate maintenance on the impedance measuring device such as replacement of each probe, impedance measurement accuracy can be improved also by this.

1 is a configuration diagram of an impedance measuring device 1. FIG. 5 is a flowchart of an impedance measurement process 50. It is a timing chart for demonstrating the relationship between the contact state of a probe and the retry of a measurement process. It is a timing chart for demonstrating the relationship between the differential value B of the voltage Vm1, and the retry of a measurement process.

  Hereinafter, an embodiment of the impedance measuring apparatus 1 will be described with reference to the accompanying drawings.

  First, the configuration of the impedance measuring apparatus 1 will be described with reference to FIG.

  The impedance measuring device 1 is a device that measures the impedance Z of the measurement object 2, and includes a pair of current supply probes 3a and 3b, a pair of voltage detection probes 4a and 4b, a drive mechanism 5, a measurement current supply unit 6, and a voltage. A detection unit 7, a first contact state detection unit 8, a second contact state detection unit 9, a processing unit 10, a storage unit 11, and an output unit 12 are provided.

  The pair of current supply probes 3 a and 3 b are connected to a pair of output terminals (not shown) of the measurement current supply unit 6. The pair of voltage detection probes 4 a and 4 b are connected to a pair of input terminals (not shown) of a differential amplifier 7 a described later that constitutes the voltage detection unit 7. The drive mechanism 5 operates based on the control signal S1 output from the processing unit 10, and causes the pair of current supply probes 3a and 3b and the pair of voltage detection probes 4a and 4b to approach the measurement object 2 simultaneously. , Again. In this case, the current supply probe 3 a and the voltage detection probe 4 a are brought into contact with and separated from one electrode 2 a of the measurement object 2 by the drive mechanism 5. On the other hand, the current supply probe 3b and the voltage detection probe 4b are brought into contact with and separated from the other electrode 2b of the measurement object 2.

  The measurement current supply unit 6 is controlled by the processing unit 10 and includes, as an example, a constant current source (AC constant current source). The measurement current supply unit 6 generates a measurement current (AC constant current having a frequency f1) Im having a predetermined current value. It supplies between both electrodes 2a, 2b of the measuring object 2 (that is, the measuring object 2) via the pair of current supply probes 3a, 3b. The measurement current supply unit 6 includes an I / V converter and an A / D converter (both not shown), and converts the supplied measurement current Im into a voltage by the I / V converter. By sampling the voltage with an A / D converter, current data (waveform data of the measurement current Im) Di indicating the amplitude of the measurement current Im is generated and output to the processing unit 10.

  The voltage detection unit 7 includes a differential amplifier 7a, a low-pass filter (hereinafter “LPF”) 7b, and an A / D converter 7c. In the differential amplifier 7a, for example, an input stage is configured using an operational amplifier, and an impedance (input impedance) between a pair of input terminals is defined to be an extremely high value. Further, as described above, in the differential amplifier 7a, a pair of voltage detection probes 4a and 4b are connected to a pair of input terminals, and a voltage (interelectrode voltage) generated between the electrodes 2a and 2b of the measuring object 2 is measured. Vm1 is detected. Further, the differential amplifier 7a amplifies the voltage Vm1 corresponding to the input voltage range of the A / D converter 7c and outputs it to the voltage signal Vm2. The LPF 7b is defined to have a cutoff frequency higher than the frequency f1 and lower than frequencies f2 and f3 described later. With this configuration, the LPF 7b removes the signal components of the frequencies f2 and f3 included in the voltage signal Vm2, and the voltage signal composed of the signal component of the frequency f1, that is, the signal component generated due to the measurement current Im. Vm3 is output. As an example, the A / D converter 7c samples the voltage signal Vm3 in synchronization with the sampling in the measurement current supply unit 6, thereby indicating voltage data indicating the amplitude of the voltage signal Vm3 (this voltage data is the voltage Vm1). Dv (which is also voltage data indicating the amplitude) is output to the processing unit 10.

  The first contact state detection unit 8 includes an AC constant current source 8a, a differential amplifier 8b, a lock-in amplifier 8c, and a comparator 8d. The AC constant current source 8a is connected to the current supply probe 3a and the voltage detection probe 4a, and is controlled by the processing unit 10 to be between the current supply probe 3a and the electrode 2a and between the voltage detection probe 4a and the electrode 2a. The detection current Ia for detecting the contact state between the current supply probe 3a and the voltage detection probe 4a can be output. In this case, an AC constant current having a frequency f2 (> frequency f1) is output as the detection current Ia. The AC constant current source 8a generates and outputs a synchronization signal Ssy1 that is synchronized with the period of the output detection current Ia.

  The differential amplifier 8b has a pair of input terminals connected to the current supply probe 3a and the voltage detection probe 4a, and inputs and amplifies the voltage Va1 generated between the current supply probe 3a and the voltage detection probe 4a. Output as signal Va2. The lock-in amplifier 8c outputs the DC voltage signal Va3 having a voltage level corresponding to the amplitude of the voltage Va1 by synchronously detecting the voltage signal Va2 with the synchronization signal Ssy1. The comparator 8d compares the DC voltage signal Va3 with a predetermined reference voltage Vref1, and outputs a contact abnormality signal Sa when the DC voltage signal Va3 is equal to or higher than the reference voltage Vref1.

  In this case, as described above, since the detection current Ia output between the probes 3a and 4a from the AC constant current source 8a is an AC constant current, the amplitude of the voltage Va1 input to the differential amplifier 8b is the current supply. It is proportional to the total resistance value of each contact resistance between the probe 3a and the electrode 2a and between the voltage detection probe 4a and the electrode 2a. Further, the reference voltage Vref1 is used when the contact contact state between the current supply probe 3a and the electrode 2a and between the voltage detection probe 4a and the electrode 2a becomes abnormal (the total resistance of each contact resistance is the upper limit resistance value). Is defined in advance as the same voltage as the DC voltage signal Va3 output from the lock-in amplifier 8c based on the voltage Va1. With this configuration, the comparator 8d outputs a contact abnormality signal Sa when the contact contact state between the current supply probe 3a and the electrode 2a and between the voltage detection probe 4a and the electrode 2a is abnormal.

  The second contact state detection unit 9 includes an AC constant current source 9a, a differential amplifier 9b, a lock-in amplifier 9c, and a comparator 9d. The AC constant current source 9a is connected to the current supply probe 3b and the voltage detection probe 4b, and is controlled by the processing unit 10 to be between the current supply probe 3b and the electrode 2b, and between the voltage detection probe 4b and the electrode 2b. The detection current Ib for detecting the contact state between the current supply probe 3b and the voltage detection probe 4b can be output. In this case, an AC constant current having a frequency f3 (> frequency f1) different from the frequency f2 is output as the detection current Ib. The AC constant current source 9a generates and outputs a synchronization signal Ssy2 that is synchronized with the period of the output detection current Ib.

  The differential amplifier 9b has a pair of input terminals connected to the current supply probe 3b and the voltage detection probe 4b, and inputs and amplifies the voltage Vb1 generated between the current supply probe 3b and the voltage detection probe 4b. Output as signal Vb2. The lock-in amplifier 9c outputs a DC voltage signal Vb3 having a voltage level corresponding to the amplitude of the voltage Vb1 by synchronously detecting the voltage signal Vb2 with the synchronization signal Ssy2. The comparator 9d compares the DC voltage signal Vb3 with a predetermined reference voltage Vref2, and outputs a contact abnormality signal Sb when the DC voltage signal Vb3 is equal to or higher than the reference voltage Vref2.

  In this case, as described above, since the detection current Ib output between the probes 3b and 4b from the AC constant current source 9a is an AC constant current, the amplitude of the voltage Vb1 input to the differential amplifier 9b is the current supply. It is proportional to the total resistance value of each contact resistance between the probe 3b and the electrode 2b and between the voltage detection probe 4b and the electrode 2b. The reference voltage Vref2 is used when the contact contact state between the current supply probe 3b and the electrode 2b and between the voltage detection probe 4b and the electrode 2b becomes abnormal (the total resistance of each contact resistance is the upper limit resistance value). And the same voltage as the DC voltage signal Vb3 output from the lock-in amplifier 9c based on the voltage Vb1. With this configuration, the comparator 9d outputs a contact abnormality signal Sb when the contact contact state between the current supply probe 3b and the electrode 2b and between the voltage detection probe 4b and the electrode 2b is abnormal.

  The processing unit 10 is composed of a CPU and executes an impedance measurement process 50 (see FIG. 2). In the impedance measurement process 50, the processing unit 10 calculates a differential value B of the voltage Vm1 for each unit time (for example, for each sampling period of the A / D converter 7c) based on the voltage data Dv, and will be described later. Comparison processing for comparing with A, contact state determination processing for determining the contact state between the probes 3a, 4a and the electrode 2a and the contact state between the probes 3b, 4b and the electrode 2b based on the contact abnormality signals Sa and Sb ( Hereinafter, the measurement process for measuring the impedance Z of the measurement object 2 is executed based on the voltage data Dv indicating the amplitude of the voltage Vm1 and the current data Di indicating the amplitude of the measurement current Im. . Further, the processing unit 10 performs control on the measurement current supply unit 6, the AC constant current sources 8 a and 9 a, and the drive mechanism 5. In addition, the differential value B in this example shall mean the value which divided the absolute value of the difference between a pair of adjacent voltage data Dv by the sampling period of the A / D converter 7c.

  The storage unit 11 includes a ROM and a RAM, and stores an operation program for the processing unit 10 and a reference value A for the differential value B in advance. The storage unit 11 also functions as a work memory for the processing unit 10. The output unit 12 is configured by a display device as an example, and displays the results of the discrimination processing and measurement processing executed by the processing unit 10.

  Next, the operation of the impedance measuring apparatus 1 will be described with reference to FIGS.

  In the impedance measuring apparatus 1, in the operating state, the processing unit 10 repeatedly detects the input of the trigger signal St indicating that the measurement object 2 is disposed at the measurement position. In this state, when detecting the input of the trigger signal St, the processing unit 10 determines that the measurement object 2 is disposed at the measurement position, and starts the impedance measurement process 50 shown in FIG.

  In the impedance measurement process 50, the processing unit 10 first controls the drive mechanism 5 to move (approach) all the probes 3 a, 3 b, 4 a, 4 b by a predetermined distance in the direction of the measurement object 2. Thus, as shown in FIG. 1, the probes 3a and 4a are brought into contact with the corresponding electrodes 2a, and the probes 3b and 4b are brought into contact with the corresponding electrodes 2b, respectively (step 51).

  Next, the processing unit 10 controls the measurement current supply unit 6, the AC constant current source 8a, and the AC constant current source 9a to operate them (Step 52). Thereby, the measurement current supply unit 6 outputs the measurement current Im from the measurement current supply unit 6 to the current path that returns to the measurement current supply unit 6 via the current supply probe 3a, the measurement object 2, and the current supply probe 3b. Start. Further, the AC constant current source 8a receives the detected current Ia from the AC constant current source 8a to the AC constant current source 8a through the current supply probe 3a, the electrode 2a of the measurement object 2 and the voltage detection probe 4a to the AC constant current source 8a. The output is started and the output of the synchronization signal Ssy1 is started. Further, the AC constant current source 9a receives the detected current Ib from the AC constant current source 9a to the AC constant current source 9a via the current supply probe 3b, the electrode 2b of the measurement object 2 and the voltage detection probe 4b. The output is started and the output of the synchronization signal Ssy2 is started.

  In the voltage detection unit 7, the differential amplifier 7 a generates a voltage Vm 1 generated between the electrodes 2 a and 2 b of the measurement object 2 due to the measurement current Im flowing through the measurement object 2. While detecting via 4a and 4b, the operation | movement which amplifies and outputs to the voltage signal Vm2 is started. Further, the LPF 7b removes the signal components of the frequencies f2 and f3 from the voltage signal Vm2, and outputs a voltage signal Vm3 composed only of the signal component (signal component of the frequency f1) generated due to the measurement current Im. The operation to start is started. Further, the A / D converter 7c starts the operation of sampling the voltage signal Vm3 and outputting it to the processing unit 10 as voltage data indicating the amplitude of the voltage signal Vm3 (also voltage data indicating the amplitude of the voltage Vm1). To do.

  In the first contact state detection unit 8, the differential amplifier 8b has a contact resistance between the current supply probe 3a and the electrode 2a of the measurement object 2, and a contact between the electrode 2a and the voltage detection probe 4a. The voltage Va1 generated due to the detection current Ia flowing through the resistor is detected via the current supply probe 3a and the voltage detection probe 4a, and the operation of amplifying and outputting the voltage signal Va2 is started. The lock-in amplifier 8c starts the operation of outputting the DC voltage signal Va3 by synchronously detecting the voltage signal Va2 with the synchronization signal Ssy1, and the comparator 8d compares the DC voltage signal Va3 with the reference voltage Vref1. Start operation.

  In the second contact state detection unit 9, the differential amplifier 9b has a contact resistance between the current supply probe 3b and the electrode 2b of the measurement object 2, and a contact between the electrode 2b and the voltage detection probe 4b. The voltage Vb1 generated due to the detection current Ib flowing through the resistor is detected via the current supply probe 3b and the voltage detection probe 4b, and the operation of amplifying and outputting the voltage signal Vb2 is started. Further, the lock-in amplifier 9c starts the operation of outputting the DC voltage signal Vb3 by synchronously detecting the voltage signal Vb2 with the synchronization signal Ssy2, and the comparator 9d compares the DC voltage signal Vb3 with the reference voltage Vref2. Start operation.

  Subsequently, in this state, the processing unit 10 starts the determination process and the comparison process (step 53), and also starts the measurement process (step 54). In this measurement process, the processing unit 10 includes voltage data Dv indicating the amplitude of the voltage Vm1 and current data Di indicating the amplitude of the measurement current Im for a predetermined period (for example, at least one cycle of the measurement current Im). Only in the storage unit 11 and based on the stored voltage data Dv and current data Di, specifically, a voltage value specified by the voltage data Dv, a current value specified by the current data Di, and The impedance Z of the measuring object 2 is measured based on the phase difference between the voltage and the current. In this case, the processing unit 10 repeatedly executes the determination process (step 55) and the comparison process (step 56) until the measurement process is completed while executing the measurement process.

  In this determination processing, the processing unit 10 determines whether the current supply probe 3a, the voltage detection probe 4a, and the electrode 2a are based on whether or not the contact abnormality signals Sa and Sb are output from the contact state detection units 8 and 9. And the contact state between the current supply probe 3b and the voltage detection probe 4b and the electrode 2b are determined to be good or bad. Specifically, when the contact abnormality detection signals Sa and Sb are output from the contact state detection units 8 and 9, the processing unit 10 detects the current supply probes 3a and 3b detected by the contact state detection units 8 and 9, respectively. In addition, it is determined that the contact state between the voltage detection probes 4a and 4b and the electrodes 2a and 2b of the measurement object 2 is defective, and contact abnormality signals Sa and Sb are output from the contact state detection units 8 and 9, respectively. When not, the contact state between the current supply probes 3a and 3b and the voltage detection probes 4a and 4b detected by the contact state detectors 8 and 9 and the electrodes 2a and 2b of the measurement object 2 is good. Is determined.

  In the comparison process, the processing unit 10 calculates the differential value B of the voltage Vm1 based on the voltage data Dv output from the A / D converter 7c, and compares it with the reference value A read from the storage unit 11. Thus, it is determined whether or not the voltage Vm1 detected by the voltage detector 7 has fluctuated more than a specified value. Specifically, when the calculated differential value B is greater than or equal to the reference value A, the processing unit 10 originally has a voltage Vm1 whose fluctuation should be within a specified range fluctuated beyond an allowable range (for example, to the voltage Vm1). On the other hand, when the calculated differential value B is less than the reference value A, the fluctuation occurring in the voltage Vm1 is within a prescribed range (that is, when the noise component is superimposed, the fluctuation exceeds the allowable range). It is determined that it is within the allowable range.

  Until the voltage data Dv and current data Di necessary for the measurement of the impedance Z are stored in the storage unit 11 and the measurement of the impedance Z is completed (step 58), the processing unit 10 performs the above-described determination processing (step 55), when it is determined that the contact state between the current supply probes 3a, 3b and the voltage detection probes 4a, 4b and the electrodes 2a, 2b of the measuring object 2 is defective, and a comparison process (step 56). In any case, when it is determined that the voltage Vm1 has fluctuated beyond the allowable range, the voltage data Dv used for the measurement of the impedance Z is likely to be an abnormal value, and such voltage data Dv is measured. Even if the impedance Z is measured by use in processing, there is a high possibility that the accurate impedance Z is not measured. For this reason, the processing unit 10 cancels the currently executed measurement process and proceeds to step 54 to re-execute the measurement process from the beginning (retry (restart) the measurement process). .

  Therefore, in this impedance measuring apparatus 1, as shown in FIG. 3, for example, a state immediately after the probes 3a, 3b, 4a, 4b are brought into contact with the corresponding electrodes 2a, 2b, that is, the probes 3a, 3b, 4a, When the state in which the contact state of 4b is good and the state in which the contact state is poor are repeated in a short time, the result of the discrimination process in step 55 becomes poor, or the result of the comparison process in step 56 falls within an allowable range. Therefore, the processing unit 10 repeats the retry of the measurement process. Further, as shown in FIG. 4, when noise is superimposed on the voltage Vm1, the result of the comparison process in step 56 exceeds the reference value A (out of the allowable range), so the processing unit 10 retries the measurement process. repeat. Thereby, since the measurement of the impedance Z using the abnormal voltage data Dv is avoided, the measurement accuracy of the impedance Z can be improved.

  In addition, when the processing unit 10 proceeds to step 54 in this way, the processing unit 10 counts the number N of times the measurement process is restarted (specifically, increments the number N) and stores it in the storage unit 11. (Step 57).

  On the other hand, until the voltage data Dv and current data Di necessary for the measurement of the impedance Z are stored in the storage unit 11 as shown in the period C of FIGS. 3 and 4, they correspond to the probes 3 a, 3 b, 4 a and 4 b. When no contact failure occurs between the electrodes 2a and 2b and no noise is superimposed on the voltage data Dv, the processing unit 10 determines the impedance based on the voltage data Dv and the current data Di stored in the storage unit 11. Z is measured and stored in the storage unit 11 as the final impedance Z. Further, when the measurement of the impedance Z is completed, the processing unit 10 ends the measurement process (step 58) and ends the determination process and the comparison process (step 59).

  Subsequently, the processing unit 10 executes control on the measurement current supply unit 6, the AC constant current source 8a, and the AC constant current source 9a to stop them (Step 60). Finally, the processing unit 10 controls the drive mechanism 5 to move all the probes 3a, 3b, 4a, 4b away from the measurement object 2 by a predetermined distance, and to measure the results (measured impedance Z and The number of retries N) is displayed on the output unit 12 (step 61). Thereby, the impedance measurement process is completed.

  As described above, in the impedance measuring apparatus 1, the processing unit 10 performs the determination process for the contact state between the corresponding electrodes 2a and 2b of the probes 3a, 3b, 4a, and 4b during the execution of the measurement process. When the contact state is not determined to be defective in the determination process until the measurement process is completed (impedance Z measurement), the impedance Z measured in the measurement process is stored in the storage unit 11 as the final measurement value. When the contact state is determined to be defective in the determination process until the measurement process is completed, a new measurement process is resumed and the determination process is repeatedly executed.

  Therefore, according to the impedance measuring apparatus 1, when the contact state between the probes 3a, 3b, 4a, 4b and the electrodes 2a, 2b is poor by repeatedly executing the discrimination process during the execution of the measurement process. Since the measurement process can be resumed, the measurement accuracy of the impedance Z is avoided by avoiding the measurement of the impedance Z under the condition that the contact state between the probes 3a, 3b, 4a, 4b and the electrodes 2a, 2b is defective. (Calculation accuracy) can be ensured. Further, when determining whether the measurement object 2 is good or bad based on the measured impedance Z, the measurement process is restarted even when the contact state becomes defective, and the measurement object 2 is accurate in the good contact state. Since the impedance Z can be measured, it is possible to reliably avoid a situation in which the non-defective measurement object 2 is erroneously determined as a defective product. As a result, it is possible to improve the yield when the measurement object 2 is manufactured.

  Moreover, in this impedance measuring apparatus 1, the comparison process which compares with the reference value A while calculating the differential value B of the voltage (voltage between electrodes) Vm1 detected by the voltage detection part 7 for every unit time is repeatedly performed with a discrimination process. When the contact state is not determined to be defective in the determination process until the measurement process is completed, and when the differential value B is not determined to exceed the reference value A in the comparison process, the impedance Z measured in the measurement process is determined. The final measurement value is stored in the storage unit 11 and displayed on the output unit 12. On the other hand, when the contact state is determined to be defective in the determination process until the measurement process is completed, or the differential value B is the reference value A in the comparison process. When it is determined that it has exceeded, a new measurement process is restarted (retry), and the determination process and the comparison process are repeatedly executed.

  Therefore, according to the impedance measuring apparatus 1, the measurement of the impedance Z is avoided because the measurement of the impedance Z using the abnormal voltage data Dv obtained when noise is superimposed on the voltage Vm1, for example, is avoided. The accuracy can be further improved.

  In addition, according to the impedance measuring apparatus 1, the number N of resumption (retry) of the measurement process is also stored in the storage unit 11 and displayed on the output unit 12. Therefore, when the number N tends to increase. For example, it is possible to determine that each of the probes 3a, 3b, 4a, 4b is deteriorating, and accordingly, appropriate maintenance is performed on the impedance measuring apparatus 1 such as replacement of the probes 3a, 3b, 4a, 4b. As a result that can be executed, the measurement accuracy of the impedance Z can be improved also by this.

  Note that the configuration in which the measurement process, the discrimination process, and the comparison process are repeated until the measurement of the impedance Z is described above. However, an upper limit number Nmax is defined in advance with respect to the number N of times the measurement process is retried. In 57, the number N is counted and the number N is compared with the upper limit number Nmax. When the number N reaches the upper limit number Nmax, the impedance measurement process 50 is terminated without starting a new measurement process. It is also possible to adopt a configuration that allows According to this configuration, it is possible to avoid a situation in which the measurement process is repeated indefinitely and the measurement time is long. Instead of the configuration in which the impedance measurement process 50 is terminated based on the comparison result between the number N and the upper limit number Nmax, an elapsed time T from the time when the measurement process is first started is measured, and this elapsed time T Of course, it is possible to adopt a configuration in which the impedance measurement process 50 is terminated when the predetermined upper limit time Tmax is reached. In this configuration as well, it is possible to avoid the situation where the measurement process is repeated indefinitely and the measurement time is long.

  Further, when the impedance measurement process 50 is terminated without measuring the impedance Z, the processing unit 10 adopts a configuration in which the result of the discrimination process or the result of the comparison process is displayed in step 61 instead of the measurement result. You can also

DESCRIPTION OF SYMBOLS 1 Impedance measuring apparatus 2 Measuring object 2a, 2b Electrode 3a, 3b Current supply probe 4a, 4b Voltage detection probe 6 Measurement current supply part 7 Voltage detection part 8 1st contact state detection part 9 2nd contact state detection part 10 Processing part A Reference value B Differential value Im Measurement current Vm1 Voltage (interelectrode voltage)
Z impedance

Claims (4)

A measurement current supply unit that supplies a measurement current to the measurement object via the first current supply probe and the second current supply probe that can contact both electrodes of the measurement object, and the measurement current flows through the measurement object. A voltage detection unit for detecting an inter-electrode voltage generated between the electrodes of the measurement object via the first voltage detection probe and the second voltage detection probe that can contact the electrodes; A first contact state detector for detecting a contact state of the first current supply probe and the first voltage detection probe with respect to one of the electrodes, the second current supply probe with respect to the other electrode of the two electrodes, and A second contact state detector for detecting a contact state of the second voltage detection probe, and at least based on a current value of the measurement current and a voltage value of the interelectrode voltage; And a processing unit for executing a measurement process of measuring the impedance of the measured object,
While the measurement process is being performed, the processing unit repeatedly executes the contact state determination process of each probe based on the detection result by each of the contact state detection units until the measurement process is completed. When the state is not determined to be defective, the impedance measured in the measurement process is used as a measurement value. When the contact state is determined to be defective before the measurement process is completed, a new measurement process is restarted and the determination process is performed. Impedance measurement device that repeatedly executes.   The processing unit repeatedly performs a comparison process together with the determination process to calculate a differential value of the voltage value of the interelectrode voltage detected by the voltage detection unit for each unit time and to compare with a predetermined reference value. The impedance measured in the measurement process is determined when the contact state is not determined to be defective by the completion of the measurement process and when the differential value is not determined to exceed the reference value in the comparison process. When the contact state is determined to be defective before the measurement process is completed or when the differential value exceeds the reference value in the comparison process, a new measurement process is restarted and the determination is performed. The impedance measuring apparatus according to claim 1, wherein the process and the comparison process are repeatedly executed.   When the number of restarts of the measurement process for one measurement object reaches a predetermined upper limit number, or the total execution time of all the measurement processes for one measurement object is determined in advance by the processing unit. The impedance measurement apparatus according to claim 1 or 2, wherein when the specified upper limit time is reached, the measurement process for the one measurement object is terminated.   The impedance measuring apparatus according to claim 1, wherein the processing unit stores in a storage unit the number of times the measurement process is resumed for one measurement object.

Images