JP2009002857A - Circuit element measuring device - Google Patents

Abstract

The present invention makes it possible to detect a contact abnormality or the like that causes an error by a simple method without requiring a dedicated circuit for contact check.
A signal generator for applying a voltage to a device under test DUT, a current detector 20 for detecting a current flowing through the device under test DUT, and a voltage detector for measuring a voltage across the device under test DUT. 30 and a control unit 50 that calculates a predetermined element constant from the detected current and voltage, a voltage abnormality occurs when the detection voltage of the voltage detection unit 30 is equal to or lower than a predetermined threshold value. The voltage determination unit 31 that outputs a signal and the current determination unit 21 that outputs a current abnormality signal when the detected current of the current detection unit 20 is equal to or greater than a predetermined threshold value. The control unit 50 includes the voltage abnormality signal and the current Based on the abnormality signal, the contact state of the Hi-side source terminal Hc on the signal generating unit 10 side or the Hi-side sense terminal Hp on the voltage detection unit 30 side with respect to the measured element DUT, and the measured element DUT itself Judges and not.
[Selection] Figure 1

Description

  The present invention relates to a circuit element measuring apparatus for measuring an element constant such as impedance inherently provided in an element to be measured, and more specifically to a technique that can perform a contact check by a simple method.

  As shown in FIG. 3, the circuit element measuring apparatus has, as its basic configuration, a signal generator 10 that applies a voltage to the device under test DUT, and a current detector 20 that detects the current flowing through the device under test DUT. And a voltage detector 30 that detects the voltage across the measured element DUT, calculates an element constant such as impedance from the detected voltage and current, and displays the measured value on a display unit (not shown).

  In this configuration, since the signal generation unit 10 and the current detection unit 20 are on the signal source side, and the voltage detection unit 30 is on the signal sense side, in this specification, the contact pin on the signal generation unit 10 side is referred to as the Hi side source. The terminal Hc, the contact pin on the current detection unit 20 side is the Lo side source terminal Lc, and the two contact pins provided on the voltage detection unit 30 side are those on the Hi side sense terminals Hp, Lo side. The Lo side sense terminal Lp is used. Note that Hi is the higher potential and Lo is the lower potential.

  By the way, when the element to be measured is an element having high voltage dependency such as a high dielectric constant type multilayer ceramic capacitor, it is necessary to know whether or not the applied voltage is appropriate.

  Therefore, in the invention described in Patent Document 1, a voltage determination unit 31 having a comparator function is connected to the voltage detection unit 30, and the voltage detected by the voltage determination unit 31 deviates from the preset upper and lower limit values. The alarm unit 32 issues a warning as a voltage abnormality if the voltage is off.

  According to this, the voltage abnormality is automatically detected and can be notified to the user by an alarm or the like, but the cause of the voltage abnormality cannot be specified.

  For example, there are the following two reasons why the voltage across the measured element DUT is lower than the lower limit. (1) When the device under test DUT itself is in a short state (low impedance side). (2) Contact abnormality when the Hi side source terminal Hc or the Hi side sense terminal Hp is not connected.

  As a user, if the device under test DUT itself is short-circuited, it is rejected as a defective product, and it is desired to perform re-measurement in the case of contact abnormality, but there is a problem in that it cannot be distinguished.

  With respect to this point, according to the invention described in Patent Document 2, contact measurement can be performed without interrupting the measurement in the impedance measurement of four terminals.

  That is, in the invention described in Patent Document 2, as shown in FIG. 4, in addition to the basic configuration including the signal generation unit 10, the current detection unit 20, and the voltage detection unit 30, the Hi side source terminal Hc and the Hi side A first DC constant current source 41 for supplying a DC constant current to a Hi side current path including the sense terminal Hp, a first DC voltmeter 42 for measuring the amplitude (DC voltage) of the current source, a Lo side source terminal Lc, As a configuration provided with a second DC constant current source 43 that supplies a DC constant current to a Lo side current path including the Lo side sense terminal Lp, and a second DC voltmeter 44 that measures the amplitude (DC voltage) of the current source. Yes.

  According to this, by measuring the DC voltage of each current path with the first DC voltmeter 42 or the second DC voltmeter 44, contact abnormality between each terminal Hc, Lc, Lp, Lc and the element DUT to be measured is detected. Although it can be detected, a dedicated circuit for contact check composed of two DC constant current sources 41 and 43 and two DC voltmeters 42 and 44 is required, and the cost is increased accordingly.

JP 2000-147038 A JP 2006-322821 A

  Therefore, an object of the present invention is to enable detection of a contact abnormality or the like that causes an error by a simple method without requiring a dedicated circuit for contact check.

  In order to solve the above-described problem, the first invention is a signal generation unit that applies a voltage to the device under measurement and a current detection unit that detects a current flowing through the device under measurement as described in claim 1. An element constant such as impedance is calculated from the voltage detection unit that measures the voltage across the measured element, the current detected by the current detection unit, and the voltage detected by the voltage detection unit. A voltage that outputs a voltage abnormality signal to the control unit when the voltage detected by the voltage detection unit is at least a predetermined threshold value or less. A determination unit; and a current determination unit that outputs a current abnormality signal to the control unit when the current detected by the current detection unit is greater than or equal to a predetermined threshold. The control unit includes the voltage abnormality signal and Based on the current abnormal signal Determining whether the contact state of the Hi-side source terminal on the signal generation unit side or the Hi-side sense terminal on the voltage detection unit side with respect to the element to be measured is good or bad. Yes.

  In the first invention, as described in claim 2, when the current abnormality signal is output from the current determination unit, the control unit determines that there is an abnormality in the measured element, and an error signal is output. Is output to the display unit, and if the voltage abnormality signal is output from the voltage determination unit, the display unit displays an error signal indicating that there is a contact failure in either the Hi-side source terminal or the Hi-side sense terminal. Output to.

  According to a second aspect of the present invention, there is provided a signal generating unit for applying a voltage to the device under measurement via the Hi side source terminal, and the device under measurement via the Lo side source terminal. A current detection unit that detects a current flowing through the voltage sensor, a voltage detection unit that measures a voltage across the measured element via the Hi side sense terminal and the Lo side sense terminal, and a current detected by the current detection unit And a control unit that calculates an element constant such as an impedance from the voltage detected by the voltage detection unit and displays it on the display unit, the control unit includes: Prior to measuring the element constant, set the good voltage range and good current range having predetermined thresholds based on the voltage value and current value absorbed from the good measured element in advance, and the above measured element at the time of actual measurement If the monitored values of voltage and current obtained from the above are out of either the good voltage range or the good current range, there is a contact failure in each of the terminals that are in contact with the device under test. It is characterized by judging.

  According to a second aspect of the present invention, as described in claim 4, the control unit has the monitor voltage value lower than the non-defective voltage range and the monitor current value smaller than the non-defective current range. In this case, it is determined that there is a contact failure with the Hi-side source terminal or the Lo-side source terminal.

  In addition, as described in claim 5, on the condition that the impedance of the element to be measured is lower than the wiring resistance connected to the Lo-side source terminal, the control unit has the monitor current value If it is within the non-defective product current range but the monitor voltage value is out of the non-defective product voltage range, it is determined that the Hi-side sense terminal or the Lo-side sense terminal has poor contact.

  According to the first invention, the voltage abnormality signal output from the voltage determination unit and the current detected by the current detection unit are predetermined when the voltage detected by the voltage detection unit is at least a predetermined threshold value or less. On the basis of the current abnormality signal output from the current determination unit when the threshold value is equal to or greater than the threshold value, the contact state of the Hi-side source terminal on the signal generation unit side or the Hi-side sense terminal on the voltage detection unit side with respect to the measured element The quality of the element to be measured itself can be determined.

  Specifically, when a current abnormality signal is output from the current determination unit, it can be determined that there is an abnormality in the element to be measured. When a voltage abnormality signal is output from the voltage determination unit, the Hi side source terminal, It can be determined that there is a contact failure in any of the Hi side sense terminals.

  According to the second invention, the control unit has a predetermined threshold based on the voltage value and the current value absorbed in advance from a non-defective device under measurement before measuring the device constant of the device under measurement. When the good voltage range and good current range are set, and the monitored value of voltage and current obtained from the above measured device during actual measurement is out of either the good voltage range or good current range, It can be determined that there is a contact failure among the terminals in contact with the element.

  Specifically, when the monitor voltage value is lower than the non-defective product voltage range and the monitor current value is smaller than the non-defective product current range, it is determined that the Hi-side source terminal or the Lo-side source terminal has poor contact. Can do.

  In addition, the monitor current value is within the above-mentioned non-defective current range on the condition that the impedance of the element to be measured is lower than the wiring resistance connected to the Lo side source terminal, but the monitor voltage value is out of the non-defective voltage range. If there is a contact failure, the Hi-side sense terminal or the Lo-side sense terminal can be determined to have a contact failure.

  Next, the first and second embodiments of the present invention will be described with reference to FIGS. FIG. 1 is a schematic configuration diagram showing a circuit element measuring apparatus according to the first embodiment, and FIG. 2 is a schematic configuration diagram showing a circuit element measuring apparatus according to the second embodiment. In these drawings, the same reference numerals are used for the same components as those in FIGS. 3 and 4 described above.

  As shown in FIG. 1, the circuit element measuring apparatus 1A according to the first embodiment has, as its basic configuration, a signal generator 10 that applies a voltage to the element DUT to be measured via the Hi-side source terminal Hc, The current detector 20 that detects the current flowing through the device under test DUT via the Lo side source terminal Lc, and the voltage across the device under test DUT through the Hi side sense terminal Hp and the Lo side sense terminal Lp are measured. And a voltage detection unit 30. Rout is an output resistance of the signal generation unit 10 and Rf is a current detection resistance of the current detection unit 20.

  A voltage determination unit 31 having a comparator function is connected to the voltage detection unit 30. A predetermined upper and lower limit value is set as a threshold value in the voltage determination unit 31, and a voltage abnormality signal is output when the detection voltage in the voltage detection unit 30 deviates from the threshold value, but according to the first embodiment When the voltage across the measured element DUT is lower than the lower limit value, the circuit element measuring apparatus 1A is (1) because the measured element DUT itself is in a short state (low impedance side). It is an object to make it possible to determine whether this is due to a contact abnormality in which the Hi-side source terminal Hc or the Hi-side sense terminal Hp is not connected. It should be understood that the abnormal voltage signal is output from the case where the voltage detected by the voltage detector 30 falls below the lower limit value.

  In the circuit element measuring apparatus 1A according to the first embodiment, the current determination unit 21 is also connected to the current detection unit 20. The current determination unit 21 outputs a current abnormality signal (current over signal) when the current detected by the current detection unit 20 is equal to or greater than a predetermined threshold.

  When the voltage abnormality signal output from the voltage determination unit 31 and the current abnormality signal output from the current determination unit 21 are analog signals, they are converted into digital signals by an A / D converter (not shown), and the control unit 50. The control unit 50 may be a CPU, MPU, microcomputer, or the like.

  Based on the voltage abnormality signal output from the voltage determination unit 31 and the current abnormality signal output from the current determination unit 21, the control unit 50 determines whether there is a contact abnormality or whether the device under test DUT is defective. to decide.

  Table 1 shows a logical table for the determination. When neither a voltage abnormality signal nor a current abnormality signal is output, it can be determined that the device under test DUT is normal.

  When there is no voltage abnormality signal and only a current abnormality signal is output, it is determined that the device under test DUT has a low impedance outside the measurement range, so the alarm unit 60 is operated to notify the user. The alarm unit may be read as a display unit.

  When both the voltage abnormality signal and the current abnormality signal are output, the voltage across the measured element DUT is below the lower limit value, and a large current that exceeds a predetermined threshold (upper limit value) flows. Therefore, it is determined that the device under test DUT itself is short-circuited inside, and the alarm unit 60 is operated to notify the user.

  When only the voltage abnormality signal is output and the current abnormality signal is not output, it is possible to determine that the Hi side source terminal Hc or the Hi side sense terminal Hp is not connected to the element DUT to be measured. Operate 60 to inform the user.

  According to the circuit element measuring apparatus 1A according to the first embodiment, by changing the alarm mode (or display mode of the display unit) of the alarm unit 60 between the case of the measured element DUT failure and the case of contact abnormality, When an error is displayed, it is possible to identify whether the error is due to contact abnormality or due to a failure of the element DUT to be measured.

  Next, a circuit element measuring apparatus 1B according to the second embodiment will be described with reference to FIG. In this circuit element measuring apparatus 1B, the measurement target is designed as a measured element DUT having a low impedance, and the contact abnormality is exclusively detected by software of the control unit 50.

  Therefore, the current determination unit 21 and the voltage determination unit 31 are removed from the circuit element measurement apparatus 1A according to the first embodiment, and the current detected by the current detection unit 20 and the voltage detection unit 30 are detected. The obtained voltage is taken into the control unit 50 via an A / D converter (not shown). In FIG. 2, Rhc is the wiring resistance of the cable connected to the Hi-side source terminal Hc, and Rlc is the wiring resistance of the cable connected to the Lo-side source terminal Lc.

  In the circuit element measuring apparatus 1B according to the second embodiment, first, the voltage value and the current value absorbed from the non-defective measured element DUT in the four-terminal measurement of the measuring apparatus 1B are stored in the memory 51 of the control unit 50. The

  In this example, as shown in Table 2, the voltage value absorbed from a non-defective device under test DUT is 0.002 V, and the current value is 19.61 mA (device under test; 10 μF capacitor, frequency 100 kHz, 1 V (V Mode), 1Ω range fixed, cable length 1m (measured voltage drop 0.023V)).

  The control unit 50 sets a non-defective voltage range and a non-defective current range having predetermined threshold values based on the voltage value and current value as described above. The threshold value may be arbitrarily determined by the user. In the following description, the good product voltage range and the good product current range may be referred to as “normal or normal value”.

  At the time of actual measurement, the control unit 50 contacts the device under test DUT when the voltage or current monitor value measured from the device under test DUT is out of either the good product voltage range or the good product current range. It is determined that there is a contact failure (contact abnormality) among the terminals Hc, Lc, Hp, and Lp.

  Referring to Table 2, first, when the Hi-side source terminal Hc is disconnected, no voltage is applied to the device under test DUT. Therefore, the measured monitor voltage value is about 0 V lower than normal and the monitor current value is about 0 A smaller than normal (both monitor voltage and monitor current are abnormal).

  Next, when the Hi side sense terminal Hp is disconnected, the voltage on the Hi side of the device under test DUT is not detected. At this time, if the device under test DUT has a high impedance, the monitor voltage measured from the device under test DUT shows an abnormal value lower than normal. On the other hand, when the impedance of the device under test DUT is lower than the wiring resistance Rlc of the cable, the voltage drop at the wiring resistance Rlc of the Lo side cable is measured. Higher outliers. The measured monitor current value is normal (monitor voltage is abnormal, monitor current is normal).

  Next, when the Lo-side sense terminal Lp is disconnected, the Lo-side voltage of the device under test DUT is not detected. At this time, if the device under test DUT has a high impedance, the monitor voltage measured from the device under test DUT shows a normal value, but the impedance of the device under test DUT is lower than the wiring resistance Rlc of the cable. In this case, a voltage value obtained by adding the voltage drop at the Lo-side wiring resistance Rlc and the voltage at both ends of the measured element DUT is measured, and thus the measured monitor voltage value shows an abnormal value higher than normal. . The measured monitor current value is a normal value (the monitor voltage is abnormal and the monitor current is normal on condition that the impedance of the device under test DUT is lower than the wiring resistance Rlc).

  Next, when the Lo-side source terminal Lc is disconnected, no current flows through the device under test DUT. Therefore, the measured monitor voltage value is about 0 V lower than normal and the monitor current value is about 0 A smaller than normal (both monitor voltage and monitor current are abnormal).

  From the above, when both the monitor voltage value and the monitor current value are abnormal, it can be determined that there is a contact failure with the Hi side source terminal Hc or the Lo side source terminal Lc.

  On the other hand, when the monitor voltage value is abnormal and the monitor current value is normal, it can be determined that there is a contact failure with the Hi-side sense terminal Hp or the Lo-side sense terminal Lp.

  However, the impedance of the device under test DUT is required to be lower than the wiring resistance Rlc. However, the circuit device measuring apparatus 1B according to the second embodiment is particularly suitable for use in the device under test DUT having a low impedance (for example, a capacitor As long as it is a low ESR measurement application), it is possible to detect a contact failure between the terminals Hc, Lc, Hp, and Lp without adding a dedicated circuit for contact check.

1 is a schematic configuration diagram showing a circuit element measuring apparatus according to a first embodiment of the present invention. The schematic block diagram which shows the circuit element measuring apparatus which concerns on 2nd Embodiment of this invention. The schematic block diagram which shows a 1st prior art example. The schematic block diagram which shows a 2nd prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Signal generation part 20 Current detection part 21 Current determination part 30 Voltage detection part 31 Voltage determination part 50 Control part 51 Memory 60 Warning part Hc Hi side source terminal Lc Lo side source terminal Hp Hi side sense terminal Lp Lo side sense terminal Rhc, Rlc wiring resistance

Claims (5)

A signal generator that applies a voltage to the device under measurement, a current detector that detects the current flowing through the device under measurement, a voltage detector that measures the voltage across the device under measurement, and the current detector In a circuit element measuring apparatus comprising a control unit that calculates an element constant such as impedance from the current detected by the voltage detection unit and the voltage detected by the voltage detection unit and displays the constant on the display unit.
A voltage determination unit that outputs a voltage abnormality signal to the control unit when the voltage detected by the voltage detection unit is at least a predetermined threshold value; and a current detected by the current detection unit is equal to or greater than a predetermined threshold value. A current determination unit that outputs a current abnormality signal to the control unit in the case of
Based on the voltage abnormality signal and the current abnormality signal, the control unit determines whether the contact state of the Hi-side source terminal on the signal generation unit side or the Hi-side sense terminal on the voltage detection unit side with respect to the measured element is good or bad. And a circuit element measuring apparatus for determining whether the measured element itself is good or bad.   When the current abnormality signal is output from the current determination unit, the control unit outputs an error signal to the display unit as an abnormality in the element to be measured, and the voltage abnormality signal is output from the voltage determination unit. 2. The circuit element measuring apparatus according to claim 1, wherein when the signal is output, an error signal is output to the display unit as a contact failure in either the Hi-side source terminal or the Hi-side sense terminal. . A signal generator for applying a voltage to the device under measurement via the Hi-side source terminal; a current detector for detecting a current flowing through the device under measurement via the Lo-side source terminal; a Hi-side sense terminal and a Lo-side sense An element constant such as an impedance is obtained from a voltage detection unit that measures a voltage across the element to be measured via a terminal, a current detected by the current detection unit, and a voltage detected by the voltage detection unit. In a circuit element measuring apparatus comprising a control unit that calculates and displays on a display unit,
Prior to measuring the element constant of the element to be measured, the control unit sets a non-defective voltage range and a non-defective current range having predetermined threshold values based on voltage values and current values previously absorbed from non-defective measured elements. And
When the monitored value of the voltage and current obtained from the device under measurement at the time of actual measurement is out of either the non-defective voltage range or the non-defective current range, the terminals that are in contact with the measured device Among them, it is determined that there is a contact failure.   The control unit contacts the Hi-side source terminal or the Lo-side source terminal Lc when the monitor voltage value is lower than the non-defective product voltage range and the monitor current value is smaller than the good product current range. The circuit element measuring apparatus according to claim 3, wherein it is determined that there is a defect.   On the condition that the impedance of the device under test is lower than the wiring resistance connected to the Lo-side source terminal, the control unit determines that the monitor current value is within the non-defective current range, but the monitor voltage value is 4 is a circuit element measuring device according to claim 3, wherein when the voltage is out of the non-defective voltage range, it is determined that the Hi-side sense terminal or the Lo-side sense terminal has poor contact.

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