JP5877048B2 - measuring device - Google Patents

Description

  The present invention relates to a measuring apparatus capable of measuring an electrical parameter such as a resistance value of a measurement object by changing measurement conditions.

  In recent years, the functions of measurement devices have become sophisticated, and various settings can be made as measurement conditions. As an example, some resistance measurement apparatuses can set various measurement conditions such as a current level and a voltage level of a measurement signal and a detection timing at which a voltage detection unit detects a voltage. Various measurement conditions need to be set appropriately by the measurer according to the type of the measurement object.

  For example, an oxide film is usually formed on contacts such as connectors, relays, and switches. When measuring the contact resistance of a contact for small current with a resistance measuring device, it is necessary to measure the resistance value while maintaining the state where an oxide film is formed. However, if a high voltage of 5 V, for example, is applied as a contact resistance measurement signal, the oxide film is destroyed by voltage, and the contacts from which the oxide film has been removed come into contact with each other to measure a low resistance value. Therefore, the resistance value including the oxide film cannot be measured. Therefore, when measuring the contact resistance of a contact for small current, it is necessary to measure with a low voltage or low current signal as a measurement signal. For example, the International Electrotechnical Commission stipulates that the open-circuit voltage between probes is limited to 20 mV or less when measuring the contact resistance of a contact as the IEC-512-2 standard. Patent Document 1 discloses a resistance measuring device that measures a resistance value in conformity with this standard.

JP-A-11-281688

  The contact resistance of the contact for small current is measured using a resistance measuring device having versatility, not a measuring device that performs resistance measurement only by setting according to IEC-512-2 as described in Patent Document 1. In this case, it is necessary to set the signal level appropriately as described above. However, since measurement conditions are left to the measurement person, there is a possibility that measurement will be performed under incorrect measurement conditions.

  In addition, when measuring the DC resistance of windings and coils, for example, if the measurement is not performed after the output of the measurement signal is started and the transient is finished and the steady state is reached, the correct measured value is obtained. I can't get it. Therefore, it is necessary to detect the voltage at an appropriate detection timing after outputting the measurement signal. However, since the measurement condition is left to the measurement person, measurement may occur during a transient phenomenon.

  For example, when measuring the DC resistance of a copper product such as a copper wire, since the copper product has a large temperature coefficient, the measured DC resistance varies depending on the temperature. Therefore, there is a measuring apparatus having a temperature correction processing function for converting measured DC resistance into DC resistance at a reference temperature. However, since it is up to the measurer to set whether or not to execute the temperature correction processing function as a measurement condition, measurement should be performed with the temperature correction processing function turned off, even when measuring copper products. There is a possibility.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a measuring apparatus that can perform measurement under appropriate measurement conditions in accordance with the type of measurement object.

The measuring apparatus according to claim 1, which has been made to achieve the above object, supplies a measurement signal to a measurement object, and the measurement object is generated by flowing the measurement signal. A measurement unit for detecting a voltage across the object and calculating a parameter of the measurement object from the current of the measurement signal and the voltage across the measurement object , and the measurement signal corresponding to each type of the measurement object measurement conditions, the measurement conditions for the detection of the both-end voltage, a measurement condition storage section for previously storing a measurement condition relating to the calculation of the parameters, and the operation unit for selecting the type or "No" of the object to be measured, in advance A measurement condition for measuring the resistance value of the measurement object is set as an initial value, and a measurement control unit for controlling the measurement unit is provided. The measurement control unit selects a type of the measurement object by the operation unit. The measurement condition storage unit When the measurement unit corresponding to the selected measurement object read and the initial value excluding the measurement condition is measured, and “unspecified” is selected in the operation unit. The measurement unit is configured to measure the resistance value at the initial value .

A measuring apparatus according to claim 2 is the measuring apparatus according to claim 1 , wherein the measurement unit includes a temperature sensor that detects a temperature of the measurement object or its environment, and a temperature detected by the temperature sensor. And the parameter can be calculated by performing a temperature correction process based on the temperature coefficient of the measurement object, and the measurement condition storage unit corresponds to the type of the measurement object that requires the temperature correction process. Thus, the presence or absence of execution of the temperature correction process and the temperature coefficient of the measurement object are stored.

The measuring apparatus according to claim 3 is the measuring apparatus according to claim 1, and when the type of the measurement object is a contact for small current, the level of the signal for measurement that does not destroy the oxide film of the contact Is stored in the measurement condition storage unit.

A measuring device according to a fourth aspect is the one according to the first aspect , wherein when the type of the measurement object is a winding or a coil, the voltage between both ends is detected from the start of the output of the measurement signal. A condition that defines a detection delay period until the measurement is stored in the measurement condition storage unit.

A measuring apparatus according to a fifth aspect is the one according to the second aspect , wherein the type of the measurement object is a copper product.

  According to the measuring apparatus of the present invention, it is possible to perform measurement under measurement conditions that are optimal for measuring a measurement object by simply selecting the type of the measurement object. For this reason, regardless of the level of proficiency of the measurer, any measurer can accurately measure the parameter of the measurement object without erroneously setting the measurement conditions.

  Also, when the measurement unit supplies a measurement signal to the measurement object, detects the voltage across the measurement object, and calculates the parameter from the current and the voltage across the measurement signal, for example, for measurement Measurement conditions relating to signals, measurement conditions such as detection delay time relating to detection of both-end voltages, and measurement conditions relating to parameter calculation are stored in the measurement condition storage unit, so that measurement can be performed under measurement conditions suitable for various measurement objects. It becomes a measuring device.

  In addition, when the temperature correction processing is executed and the temperature coefficient of the measurement object is stored in the measurement condition storage unit in correspondence with the type of the measurement object that requires the temperature correction process, only the measurement object is selected. Thus, the measurement value subjected to the temperature correction process can be obtained even if the measurer does not particularly set the measurement condition. In particular, since copper products are measured relatively frequently and have a large temperature coefficient, it is convenient to store them as measurement objects.

  In addition, when the conditions that define the level of the signal for measurement that does not destroy the oxide film of the contact for small current are stored in the measurement condition storage unit, just by selecting the contact for small current as the measurement object, anyone can The contact resistance of small current contacts can be measured accurately. In addition, when a condition that defines a detection delay period from the start of output of the measurement signal to the detection of the voltage at both ends is stored in the measurement condition storage unit in correspondence with the winding and coil, the measurement object is wound as a measurement object. By simply selecting a wire or coil, anyone can measure the resistance of a winding or the like in a steady state rather than during a transient event.

It is a block diagram which shows the use condition of the measuring apparatus to which this invention is applied. It is a flowchart which shows operation | movement of the measuring apparatus to which this invention is applied. It is a schematic diagram which shows the example of a display of the display part of the measuring apparatus to which this invention is applied.

  Examples of the present invention will be described in detail below, but the scope of the present invention is not limited to these examples.

  A measuring apparatus 1 to which the present invention is applied is, for example, a direct current resistance measuring apparatus. As shown in FIG. 1, a measuring unit 2, an operation unit 3, a display unit 4, a measurement condition storage unit 5, a measurement control unit 6, and A time measuring unit 7 is provided, and the DC resistance (an example of a parameter) of the measurement object (DUT) 90 can be measured.

  The measurement unit 2 includes a measurement signal supply unit 11, a voltage detection unit 12, a temperature sensor 13, and a measurement value calculation unit 14. The measurement signal supply unit 11 supplies a DC measurement signal to the DUT 90 via the probes Pi1 and Pi2. The measurement signal supply unit 11 can vary and output a constant current value supplied as a measurement signal and an open voltage (both examples of measurement conditions) for outputting the measurement signal. These measurement conditions are instructed (set) from the measurement control unit 6 to the measurement signal supply unit 11. The constant current value and open circuit voltage of the measurement signal may be set as a measurement range (input range).

  The voltage detector 12 detects the voltage across the DUT 90 generated by the measurement signal flowing through the DUT 90 via the probes Pv1 and Pv2. The voltage detection unit 12 instructs the measurement control unit 6 to detect the detection timing (example of measurement conditions) for detecting the voltage. The voltage detection unit 12 outputs the detected both-end voltage to the measurement value calculation unit 14.

  The temperature sensor 13 detects the temperature of the DUT 90 or the environmental temperature of the DUT 90 using, for example, a thermocouple, a platinum resistance thermometer, and the like, and outputs the detected temperature to the measured value calculation unit 14. It is preferable that the temperature sensor 13 is detachably connected to the measurement unit 2 with a cable and can measure the temperature at an arbitrary position of the DUT 90.

The measurement value calculation unit 14 calculates the resistance value of the DUT 90 according to Ohm's law from the constant current output to the measurement signal supply unit 11 and the both-end voltage detected by the voltage detection unit 12, and the measurement control unit 6 Output to. Further, the measured value calculation unit 14 can execute temperature correction processing (other examples of measurement conditions) of the measured resistance value. The temperature correction process is a process for converting the measured resistance value into a resistance value at the reference temperature. Specifically, the measurement value calculation unit 14 is based on the temperature T detected by the temperature sensor 13 and the temperature coefficient α instructed from the measurement control unit 6 when the temperature correction process is instructed from the measurement control unit 6. Then, the measured resistance value _RT is converted into a resistance value R ₀ at a reference temperature T ₀ (for example, 20 ° C.). The conversion formula for correcting the temperature is expressed by the following formula (1).
R ₀ = R _T / (1 + α (T−T ₀ )) (1)

  The operation unit 3 is operated by the measurer to select the type of the DUT 90 or to manually set various measurement conditions, for example, a selection button, a cursor key for moving the cursor up / down / left / right, and a numerical value A numeric keypad for setting. The content operated by the operation unit 3 is input to the measurement control unit 6.

  The display unit 4 is, for example, a liquid crystal panel that can display measurement values, measurement conditions, and the like. Display content of the display unit 4 is controlled by the measurement control unit 6.

  The measurement condition storage unit 5 is a non-volatile memory such as a ROM (read only memory), a flash ROM, or a hard disk, and stores measurement conditions corresponding to the type of the DUT 90 in advance. The measurement conditions include many measurement conditions such as the open voltage of the measurement signal, the constant current value of the measurement signal, the detection delay time, and the presence / absence of execution of the temperature correction process. It is only necessary to store measurement conditions different from the measurement conditions used in the measurement. In addition, you may memorize | store all the measurement conditions used for a measurement for every kind of measuring object. The measurement conditions stored in the measurement condition storage unit 5 will be described later.

  The measurement control unit 6 includes, for example, a CPU 6a (central processing unit) and a memory 6b that stores a program for its operation, and comprehensively controls the operation of each unit of the measurement device 1. The measurement control unit 6 reads a measurement condition corresponding to the type of DUT 90 selected by the operation unit 3 from the measurement condition storage unit 5 and causes the measurement unit 2 to measure according to the measurement condition. The memory 6b may be shared with the measurement condition storage unit 5.

  The time measuring unit 7 is for measuring the detection delay period. The detection delay period is a period from the time when the measurement signal supply unit 11 starts outputting the measurement signal to the time when the voltage detection unit 12 starts detecting the voltage. The time measuring unit 7 includes, for example, a real time clock and an internal timer of the CPU 6a. The time measurement unit 7 is set with a detection delay period in the measurement control unit 5, immediately starts time measurement in response to an instruction from the measurement control unit 5, and sends a signal indicating that the measurement control unit 5 immediately ends when the detection delay period elapses. 7 is output.

  Next, operation | movement of the measuring apparatus 1 is demonstrated along the flowchart of FIG.

  When the power of the measuring device 1 is turned on (step S1), the CPU 6a of the measurement control unit 6 reads the operation program in the memory 6b and executes an initialization process (step S2). In this initialization process, the measurement control unit 6 displays a “measurement object selection screen” shown in FIG. 3 on the display unit 4 as an example. On the “measurement object selection screen”, the type of the measurement object is displayed so as to be selectable. The figure shows an example in which “small current contact point”, “copper product”, and “winding / coil” are displayed as objects to be measured.

  When measuring the contact resistance of the small current contact as the DUT 90, the measurer operates the cursor key or the like of the operation unit 3 to select “small current contact” (step S3). The small current contact is, for example, a contact used for flowing a current of 10 mA or less at a DC voltage of 10 V or less. The DC voltage may be 12V or lower, 24V or lower, or the like. What is called for a minute current is also included. When “small current contact” is selected, the measurement control unit 6 reads the measurement condition corresponding to the “small current contact” from the measurement condition storage unit 5 (step S4). Examples of the measurement conditions are shown in Table 1. As shown in the table, the measurement condition storage unit 5 stores at least a condition that defines the level of the measurement signal that does not destroy the oxide film on the contact, corresponding to the “small current contact”. Here, a predetermined open-circuit voltage (DC voltage 20 mV as an example) that does not destroy the contact oxide film is stored as the level of the measurement signal. As a condition for defining the level of the measurement signal, a predetermined current (DC current 1 mA as an example) that does not destroy the oxide film of the contact may be stored. Further, the measurement range may be stored as a condition for defining the level of the measurement signal.

  The measurement control unit 5 sets the read measurement conditions in the measurement unit 2 (step S5). In addition, the “normal” detection delay period in Table 1 and other measurement conditions not specified in Table 1 are preset as initial values in the operation program of the CPU 6a as measurement conditions that are normally used. The measurement control unit 5 sets the initial value in the measurement unit 2.

  Specifically, the measurement control unit 5 causes the measurement signal supply unit 11 to output a measurement signal with an open-circuit voltage of a DC voltage of 20 mV. In addition, the measurement control unit 5 causes the time measurement unit 7 to start measurement of a normal detection delay period when the measurement signal is output, and immediately after the measurement of the period has elapsed, the voltage detection unit 12 causes the DUT 90 to Both-end voltage is detected (step S6). Subsequently, the measurement value calculation unit 12 calculates a resistance value without temperature correction processing and outputs the resistance value to the measurement control unit 5 (step S7).

  The measurement control unit 5 displays the measured value measured by the measurement unit 2 on the display unit 4. The measurement of the contact resistance of the small current contact is thus completed.

  In this way, by selecting "Small Current Contact" from the initial screen that appears when the power is turned on, the oxide film on the contact can be destroyed no matter what measurer performs the measurement. The contact resistance can be measured.

  Next, the case where “copper product” is selected on the “measurement object selection screen” shown in FIG. 3 will be described. When measuring a resistance value of a copper wire or a copper plate as the DUT 90, the measurer selects “copper product” (step S3). When “copper product” is selected, the measurement control unit 6 reads the measurement condition corresponding to “copper product” from the measurement condition storage unit 5 (step S4). Table 2 shows examples of measurement conditions corresponding to “copper products”. As shown in the table, the measurement condition storage unit 5 stores in advance at least a temperature correction process and a copper temperature coefficient.

  The measurement control unit 5 sets the read measurement conditions in the measurement unit 2 (step S5). Specifically, the measurement control unit 5 outputs a normal measurement signal from the measurement signal supply unit 11. In addition, the measurement control unit 5 causes the time measurement unit 7 to start measurement of a normal detection delay period from the time when the measurement signal is output, and immediately after the period has elapsed, the voltage detection unit 12 causes the DUT 90 to Both-end voltage is detected (step S6). Further, since the temperature correction process is “Yes”, the measurement control unit 5 causes the measurement value calculation unit 14 to read the temperature from the temperature sensor 13 (step S6). The normal measurement signal level and the normal detection delay period are preset as initial values in the operation program of the CPU 6a.

  Subsequently, the measurement value calculation unit 14 first calculates a resistance value, and further performs a temperature correction process using the above-described equation (1) using the read temperature T and the temperature coefficient set by the measurement control unit 5. The resistance value at the reference temperature is calculated and output to the measurement control unit 6 (step S7). The measurement control unit 6 displays the resistance value converted into the reference temperature on the display unit 4 (step S8).

  In this way, by selecting “Copper Products” from the screen displayed when the power is turned on, no matter what measurer performs the measurement, the resistance value of the copper DUT 90 at the reference temperature is measured. it can.

  Next, a case where “winding / coil” is selected on the “measurement object selection screen” shown in FIG. 3 will be described. When “winding / coil” is selected (step S3), the measurement control unit 6 reads the measurement condition corresponding to “winding / coil” from the measurement condition storage unit 5 (step S4). Table 3 shows an example of measurement conditions corresponding to “winding / coil”. As shown in the table, the measurement condition storage unit 5 stores in advance a condition that defines at least the detection delay time. In the table, as an example of a condition for defining the detection delay time, a condition for making the detection delay time a predetermined multiple (100 times as an example) longer than a normal period is stored. This predetermined multiple is set to a multiple that ensures that the transient phenomenon that occurs when the measurement signal is started to be applied to the winding ends and the steady state is reached.

  The measurement control unit 5 sets the read measurement conditions in the measurement unit 2 (step S5). Specifically, the measurement control unit 5 outputs a normal measurement signal from the measurement signal supply unit 11. In addition, the measurement control unit 5 causes the time measurement unit 7 to start measurement for a period 100 times the normal detection delay time from when the measurement signal is output, and immediately after the period has elapsed, the voltage detection is performed. The unit 12 is caused to detect the voltage across the DUT 90 (step S6). Subsequently, the measurement value calculation unit 12 calculates a resistance value without temperature correction processing and outputs the resistance value to the measurement control unit 5 (step S7). The measurement control unit 6 displays the resistance value on the display unit 4 (step S8). The normal measurement signal level and the normal detection delay period are set in advance in the operation program of the CPU 6a.

  As described above, since the detection delay period is set to a sufficiently long period, the voltage between both ends can be detected after the transient phenomenon due to the application of the measurement signal ends and the steady state is reached. Therefore, no matter what measurer measures, it is possible to accurately measure the DC resistance value of the winding or coil.

  As an example of the condition for defining the detection delay period, a condition that the detection delay period is calculated by a calculation formula may be stored in the measurement condition storage unit 5. The calculation formula itself to be used may be stored in the measurement condition storage unit 5 or may be included in the operation program of the CPU 6a.

Shows an example of calculation formulas for calculating the detection delay time t _s in equation (2).
t _s = (− (L / R) × ln (1-IR / V)) × M (2)
Here, L is the inductance of DUT 90, R is (resistance value of DUT 90) + (wiring resistance of probes Pi1 and Pi2) + (contact resistance of probes Pi1 and Pi2), I is a constant current flowing as a measurement signal, and V is The open voltage of the measurement signal supply unit 11, ln is a natural logarithm, and M is a margin magnification. M is set to an appropriate value of about 5 to 50 (for example, 10).

  Since the values of the inductance L and the resistance value R in the equation (2) are unknown, the measurement control unit 5 displays the L and R input setting screens for inputting the values of L and R on the display unit 4 ( (Not shown). The measurer operates the operation unit 3 to input L and R values (step S11). In this case, since the resistance value R is before measurement, the measurer inputs a value larger than the expected resistance value as R. In the equation (2), I and V are values that the measurement control unit 6 outputs from the measurement signal supply unit 11 during normal measurement, and are set as initial values in the operation program of the CPU 6a.

Measurement control unit 5, L is input in step S11, R, and, I to output the measurement unit 2 obtains the detection delay time t _s and the expression (2) by calculating using a V, the detection delay period It is measured in the measurement unit 2 at t _s, obtaining a resistance value (step S5 to S8).

  Thus, by using the equation (2), it is possible to calculate the detection delay period in accordance with the values of L, R, I, and V. That is, the period during which the voltage (current) of the measurement signal is sufficiently stabilized can be accurately calculated without being excessive or insufficient. Therefore, a more accurate measurement value can be measured in as short a time as possible.

  The calculation formula for calculating the detection delay period is not limited to the formula (2). For example, the time constant τ = L / R is calculated from L and R input in step S11, and the margin magnification (about 5 to 50) is calculated for the τ. The detection delay period may be calculated by multiplying by an appropriate value.

  When “not specified” is selected on the “measurement object selection screen” shown in FIG. 3, the measurement apparatus 1 operates as a normal resistance measurement apparatus. In this case, the open voltage of the measurement signal, the detection delay period, and the like are set from the measurement control unit 6 to the measurement unit 2 with normal values (initial values), but manually set to arbitrary values by the measurer. You can also.

  In addition, although the measuring apparatus 1 which measures DC resistance was demonstrated, you may apply this invention to the measuring apparatus which outputs the signal for an alternating current measurement and measures alternating current resistance (other examples of a parameter). In that case, at least one of the AC constant current value of the measurement signal, the open-circuit voltage for outputting the measurement signal, the AC frequency, and the detection delay period in the measurement condition storage unit 5 in correspondence with the type of the measurement object. One measurement condition is memorized. Further, the measurement device capable of measuring the AC resistance and the DC resistance stores the distinction as a measurement condition whether the measurement signal is AC or DC. Further, the present invention may be applied to a measuring apparatus that measures impedance, capacitance, inductance, and the like as parameters of a measurement object.

  In addition, although the example of “copper product” is described as the measurement object to be temperature-corrected, other metals or conductors such as aluminum (temperature coefficient: 0.0040) may be selected as the measurement object. The insulating material may be selected as a measurement object. In addition, although three examples of “contact for small current”, “copper product”, and “winding / coil” have been described as the measurement object, the measurement object is not limited to these examples, and other measurement objects May be selected and measured. Further, other measurement conditions other than the measurement conditions shown in Tables 1 to 3 may be specified.

1 is a measurement device, 2 is a measurement unit, 3 is an operation unit, 4 is a display unit, 5 is a measurement condition storage unit, 6 is a measurement control unit, 6a is a CPU, 6b is a memory, 7 is a time measurement unit, and 11 is a measurement The signal supply unit 12, the voltage detection unit 12, the temperature sensor 13, the measurement value calculation unit 14, and the measurement objects Pi 1, Pi 2, Pv 1, and Pv 2 are probes.

Claims (5)

A measurement signal is supplied to the measurement object, a voltage across the measurement object generated by the flow of the measurement signal is detected, and a parameter of the measurement object is determined from the current of the measurement signal and the voltage across the measurement signal. A measuring unit to calculate ,
A measurement condition storage unit for preliminarily storing measurement conditions relating to the measurement signal corresponding to each of the types of measurement objects, measurement conditions relating to detection of the both-end voltage, and measurement conditions relating to calculation of the parameters ;
An operation unit for selecting the type of the measurement object or “not specified” ;
A measurement condition for measuring the resistance value of the measurement object is set as an initial value in advance, and includes a measurement control unit that controls the measurement unit,
The measurement control unit, when the type of the measurement object is selected by the operation unit, the measurement condition corresponding to the selected measurement object read from the measurement condition storage unit, and the measurement condition A measurement apparatus characterized by causing the measurement unit to measure with the initial value excluding, and causing the measurement unit to measure the resistance value with the initial value when “undesignated” is selected on the operation unit . The measurement unit includes a temperature sensor that detects the temperature of the measurement object or its environment, and performs temperature correction processing based on the temperature detected by the temperature sensor and the temperature coefficient of the measurement object to obtain the parameter. Can be calculated,
The measurement condition storage unit stores the presence / absence of execution of the temperature correction processing and the temperature coefficient of the measurement target in correspondence with the type of the measurement target that requires the temperature correction processing. The measuring device according to claim 1 , wherein When the type of the measurement object is a small current contact, a condition that defines the level of the measurement signal that does not destroy the oxide film of the contact is stored in the measurement condition storage unit. The measuring apparatus according to claim 1 . When the type of the measurement object is a winding or a coil, a condition that defines a detection delay period from the start of output of the measurement signal to the detection of the both-end voltage is stored in the measurement condition storage unit. The measuring apparatus according to claim 1 , wherein: The measuring apparatus according to claim 2 , wherein the type of the measurement object is a copper product.

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